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USGS2023

Modeling, mapping, and measuring the risk of freshwater invasive species across Alaska

Freshwater ecosystems of the Alaskan Arctic and Subarctic provide resources that are culturally, ecologically, and economically invaluable. Presently, these regions are relatively free of the impacts from invasive species compared to southern latitudes. To date, there have been relatively few verified introductions of aquatic invasive species (AIS) to freshwater ecosystems in Alaska. The expanding list and distribution of AIS has led to significant negative ecological and economic impacts (e.g., waterweed Elodea nuttalli ; E. canadensis and northern pike Esox Lucius introduced outside its native range in Alaska). Escalating human activity across Alaskan lands and waters, coupled with rapidly shifting environmental conditions, increases the potential for new species introductions and subsequent establishment. Creating a proactive framework for well-informed decision-making and action can improve the effectiveness of prevention efforts and bolster decision support tools that help resource managers direct limited resources. Prioritizing AIS that may be introduced and become established, as well as the locations at highest risk of invasion, is foundational to building a proactive invasive species management framework in Alaska. This project sought to identify and prioritize AIS known to be invasive in the contiguous United States, evaluate current and future habitat suitability for AIS in Alaska, and assess potential for AIS to be transported to habitats across Alaska, utilizing similar assessment methods as implemented for Bering Sea marine invasive species and non-native plants in Alaska. To accomplish this goal, the objectives of the project were to: 1) develop a formal ranked list of potential AIS to freshwater systems of Alaska; 2) assess the level of establishment risk for potential AIS by developing habitat suitability models for waterbodies across Alaska; and 3), identify potential pathways and specific vectors for high-risk AIS to invade Alaska and develop a framework for how vector analysis will be completed to understand transport risk. Overall, our goal is horizon scanning which is defined by Roy et al. (2019) as “a systematic examination of potential threats and opportunities, within a given context, and likely future developments, which are at the margin of current thinking and planning.” The scans include pathway analyses and risk screening of species present at pathway origin points, with a focus on identifying species at high risk of being introduced, becoming established, spreading, and causing harm. We refined a list of 28 AIS from a list of hundreds based on characterizations of species’ invasiveness and species’ proximity to Alaska (USGS 2020; GBIF 2022). Next, we evaluated the relative invasiveness of individual species to create an initial AIS ranking. We sought to characterize habitat suitability of AIS by selecting variables that were continental in scale, covering North America to include Alaska as well as the lower 48 states comparing natural discharge, sub-basin average terrain slope (degrees), average silt fraction, average organic carbon, lithological class, and human footprint in sub-basin in 2009. We estimated AIS habitat suitability across the entire state of Alaska using the physiological tolerances of the AIS (Appendix 2). We also evaluated pathways and vectors for the introduction of AIS (Appendix 2). Many pathways and vectors considered did not meet the criteria for Alaska or freshwater systems. Of the 28 ranked species that we categorized as very high, high, and moderate levels of invasiveness; all three risk groups included fish and mollusks (Appendix 2). One commonality of the very high-invasiveness-ranked species was the availability of Ecological Risk Screening Summary documents (USFWS, 2022) produced by U.S. Fish and Wildlife Service (USFWS), except for the goldfish ( Carassius auratus ) and the New Zealand mudsnail ( Potamopyrgus antipodarum ). The Ecological Risk Screening Summary is now available for New Zealand mudsnails. In general, fish species often ranked very high or high in invasiveness and included sportfish and aquarium fish, suggesting the importance of pathways such as aquarium trade, fishing industry, intentional (but illegal) introductions of sportfishes and aquarium fishes for establishment. The technique we used for habitat suitability models necessitated aquatic environmental datasets that were continental in scale, which was often interpolated from very coarse resolution source data layers, particularly in Alaska. Better spatial data representing aquatic environments would likely improve this approach. While the lack of introductions in Alaska and nearby provinces and states is encouraging, the lack of occurrence data for the focal species also created complications for habitat suitability modeling. Despite the challenges, the habitat suitability models indicated limited suitability for warmwater species while some species, such as Brook trout (S alvelinus fontinalis ), have high habitat suitability across Alaska no matter what threshold approach is taken. Some environmental predictors were more important than others. Specifically, the most important predictor variable, ‘frost free days,’ was critical for 15 out of 28 species as expected due to harsh winter conditions in Arctic and Subarctic regions. The second most important predictor was ‘subbasin land surface runoff’, a variable that indicates the amount of discharge and runoff, while the third most important predictor was ‘snow cover’ another indication of winter conditions. Overall, the ability to understand the effect of future climate scenarios on the establishment of AIS was challenging. A detailed dataset of freshwater temperatures and water chemistry (e.g., pH, calcium) would greatly improve the ability to predict invasiveness of freshwater species to Alaska’s ecosystems on a regional basis. Future studies may benefit from a more focused geographic scope examining a group of subbasins or a regional basin rather than the entire state. These drainages could be selected based upon the mostly likely locations of introduction pathways. The two most prevalent pathway risks for AIS are in-state transfer and stowaways/contaminants. Although there are examples of introductions from other pathways, the risk is somewhat mitigated by Alaska’s climate and regulations. However, variable application of protocols for inspection and cleaning of fishing gear, watercraft, and other similar items while traveling into Alaska as well as transferring from waterbody to waterbody within the state creates a substantial risk in introducing invasive species. We plot cumulative invasive vulnerability for all subbasins and for the top 10% of subbasins (Appendix 3).

Alaska↗

USGS1959

Ground-water resources of Riverton irrigation project area, Wyoming, with a section on chemical quality of ground water

The Riverton irrigation project area is in the northwestern part of the Wind River basin in west-central Wyoming. Because the annual precipitation is only about 9 inches, agriculture, which is the principal occupation in the area, is dependent upon irrigation. Irrigation by surface-water diversion was begum is 1906; water is now supplied to 77,716 acres and irrigation has been proposed for an additional 31,344 acres. This study of the geology and ground-water resources of the Riverton irrigation project, of adjacent irrigated land, and of nearby land proposed for irrigation was begun during the summer of 1948 and was completed in 1951. The purpose of the investigation was to evaluate the ground-water resources of the area and to study the factors that should be considered in the solution of drainage and erosional problems within the area. The Riverton irrigation project area is characterized by flat to gently sloping stream terraces, which are flanked by a combination of badlands, pediment slopes, and broad valleys. These features were formed by long-continued erosion in an arid climate of the essentially horizontal, poorly consolidated beds of the Wind River formation. The principal streams of the area flow south-eastward. Wind River and Fivemile Creek are perennial streams and the others are intermittent. Ground-water discharge and irrigation return flow have created a major problem in erosion control along Fivemile Creek. Similar conditions might develop along Muddy and lower Cottonwood Creeks when land in their drainage basins is irrigated. The bedrock exposed in the area ranges in age from Late Cretaceous to early Tertiary (middle Eocene). The Wind River formation of early and middle Eocene age forms the uppermost bedrock formation in the greater part of the area. Unconsolidated deposits of Quaternary age, which consist of terrace gravel, colluvium, eolian sand and silt. and alluvium, mantle the Wind River formation in much of the area. In the irrigated parts of the project, water from domestic use is obtained chiefly from the sandstone beds of the Wind River formation although some is obtained from the alluvium underlying the bottom land and from the unconsolidated deposits underlying the lower terraces along the Wind River. Although adequate quantities if water for domestic use are available from the Wind River formation, there quantities are not considered to be large enough to warrant pumping of ground water for irrigation. Only a few wells are in the nonirrigated part of the area. When this new land is irrigated, a body of ground water will gradually form in the terrace deposits and the alluvial and colluvial-alluvial deposits. Eventually, the terrace deposits may yield adequate quantities of water for domestic and stock use, but only locally are the alluvial and colluvial-alluvial deposits likely to become suitable aquifers. In the Riverton irrigation project area, ground water occurs under water-table conditions near the surface and under artesian conditions in certain strata at both shallow and greater depths. Irrigation is the principal source of recharge to the shallow aquifers; the water level in wells that tap these aquifers fluctuates with irrigation. The depth to water in the shallow wells ranges from less than 1 foot to about 30 feet below the land surface, depending on the season of the year and on the length of time the land has been irrigated. The water level in the wells that tap the deep confined aquifers , which receive recharge indirectly from surface sources, fluctuates only slightly because the recharge and discharge are more constant. In most places the depth to water in wells penetrating the deep confined aquifers is mush greater than that in shallow wells. but in certain low areas water from the deep aquifers flows at the surface from wells. Ground water moves from the area of recharge in the direction of the hydraulic gradient and is discharges either by evapotranspiration; by inflow into streams, drains, or lakes; by pumping or flow of wells; or by flow of springs. Waterlogging and the associated development of saline soils are common in parts of the Riverton irrigation project and adjacent irrigated land. The waterlogging is in part the result of the infiltration of irrigation water in excess of the capacity of the aquifers to store and transmit this added recharge. The solution of the drainage problems involves the consideration of a number of factors, some of which are inadequately known in some parts of the area and require further investigation before fully effective drainage measures can be designed. The results of an aquifer test to determine the hydrologic characteristics of the Wind River formation at Riverton indicate a transmissibility of 10,000 gallons per day per foot (10,000 gpd per ft) and a storage coefficient of 2 x 10 -4 . The results of the test provide a part of the necessary foundation for the solution of present and future water-supply problems at Riverton and throughout the project area. Water from shallow aquifers in irrigated tracts in the Riverton irrigation project area generally contains large amounts of dissolved solids that were leached from the soil and rocks by infiltrating irrigation water. However, wells tapping beds that receive considerable recharge from influent canal and drain seepage yield water of relatively low mineralizatoin. Dilute water is obtained also from some shallow wells in the alluvial bottom lands and on low stream terraces that border the Wind Rover. Water from deep aquifers generally is more dilute than that from shallow aquifers. However, ground water from the deep aquifers, unmixed with irrigation water, generally has a percent sodium greater than 80. Analyses of salt crusts on the ground surface in low areas that are affected by effluent seepage and a high water table show predominance of sodium sulfate salinity, and from determinations of the water-soluble and acid-soluble substances in several samples of soil and shale it is apparent that harmful concentrations of salts are being deposited in poorly drained area. Although most of the soul in the Midvale irrigation district is of the normal arid type, analyses of soil samples show that saline, nonsaline alkaline, and saline alkaline types also are present.

Wyoming↗

USGS1984

Geologic evolution, sedimentation, and paleoenvironments of the Angola Basin and adjacent Walvis Ridge: Synthesis of results of Deep Sea Drilling Project Leg 75

The section recovered at Site 530 (Holes 53OA and 530B) consists of eight sedimentary units and one basalt unit. The composition of the basalt recovered in Hole 53OA is distinct from typical mid-ocean ridge basalts (MORBs) but is similar to that of Hawaiian tholeiites and basalt from the central part of Walvis Ridge. Throughout most of its history, the southern Angola Basin received large volumes of redeposited material in the form of turbidites and, most recently, debris-flow deposits. Most of this material was derived from Walvis Ridge to the south, but thickness trends of acoustic units suggest that some of the sediment was derived from the African continental margin to the east. The basal sedimentary unit (Albian to Santonian) at Site 530 contains 262 beds of black shale that are interbedded with green and red claystone. Black shale makes up less than 10% of the total section, but in two cores of early Turonian age, black shale beds compose about 50% of the section. The black shales contain up to 19% organic carbon (average of about 5%) that is mainly of autochthonous marine origin but with significant contributions from terrigenous organic matter. The origin of these more- and less-reduced interbedded lithologies with varying amounts and types of organic matter, and variable amounts of pelagic, hemipelagic, and turbiditic sediment is complex and cannot be explained by any one simple process. Many factors affecting the concentration of dissolved oxygen in the bottom waters of the Angola Basin varied throughout the middle Cretaceous to produce bottom-water conditions that fluctuated between mildly oxic and oxygen-deficient, but most of the time bottom-waters and sediment-interstitial waters were sufficiently oxic to permit the accumulation of red oxidized sediment. A relatively complete sedimentary record of the Cretaceous/Tertiary boundary was recovered within a sequence of mudstone and marlstone turbidites in Hole 530A. There is a significant increase in the concentration of iridium above background levels at the boundary. High concentrations of many other elements also occur within the same stratigraphic interval as the iridium anomaly. Furthermore, there is a marked decrease in CaCO3 in the Tertiary strata above the iridium anomaly which suggests that the production of shallow-water carbonate also may have been affected by whatever caused elevated concentrations of iridium and other elements. These observations are consistent with the asteroid-impact theory proposed to explain the worldwide occurrence of an iridium anomaly at the Cretaceous/Tertiary boundary. The Cenozoic history of the Angola Basin was controlled mainly by (1) restriction of bottom-water flow from the south by Walvis Ridge; (2) development of glaciation on Antarctica; (3) opening of circulation passages in the southern oceans; (4) rapid turnover of cold, nutrient-rich waters that resulted in high productivity of diatoms; (5) influx of terrigenous sediment mainly by turbidity currents; and (6) production and preservation of carbonate sediment. The most distinctive Cenozoic event recorded in the section at Site 530 is the beginning of extensive glaciation on Anarctica and concomitant initiation of modern thermohaline bottom-water circulation that is manifested as a middle Eocene to middle Oligocene unconformity or compressed section accompanied by a drastic decrease in accumulation of CaCO3. Diatom abundances in HPC cores from Walvis Ridge (Site 532) and Angola Basin (Hole 53OB) indicate that Benguela upwelling in these areas began in the late Miocene, reached a peak in the late Pliocene to early Pleistocene, and declined thereafter. Short-term variations in sediment composition at Site 532 are manifested as cyclic variations in concentrations of clay, CaCO3, and organic carbon with average periodicities of about 30-60 k.y. The main variability that produced the cycles probably was the influx of terrigenous clastic material which diluted the CaCO3. The sediment at Site 532 also contains several percent organic carbon that is dominantly of marine origin, but with significant terrigenous components. Data from multichannel seismic, gravity, and magnetic surveys were used to define the regional stratigraphic and structural evolution of Walvis Ridge and adjacent Cape and Angola basins. Six structural provinces are recognized, four on Walvis Ridge and two additional provinces that correspond to the Cape and Angola basins. The two eastern structural provinces on Walvis Ridge are underlain by continental crust. The two western structural provinces are underlain by oceanic basement. Two main directions of faults are evident in seismic profiles, one trending N 10° and one trending N 60°. The N 60° trend corresponds to the general orientation of the northern and southern flanks of Walvis Ridge as well as to the dominant direction of fracture zones. During the first phase of separation of Africa from South America (ca. 120-130 m.y. ago), a voluminous mass of volcanics was emplaced simultaneous with the emplacement of basalt in the Parana Basin of Brazil and the Kaokoveld Region of South Africa. This period of volcanism also formed the series of seaward-dipping internal basement reflectors that are characteristic of the two structural provinces of Walvis Ridge. A system of fault blocks developed in the brittle upper part of the newly formed crust. During the second phase of rifting, which ended before late Aptian, more tilted fault blocks were created in the upper brittle stratified continental crust. Magnetic lineations in basement rocks in the Angola and Cape basins in the vicinity of Walvis Ridge are not distinct but suggest that oceanic crust began to be emplaced between 120 and 112 m.y. ago (Barremian to early Aptian). At least part of the oceanic crust of the central plateau of eastern Walvis Ridge (structural province 3) may have been emplaced before any oceanic crust formed in the adjacent basins. A ridge jump occurred during the late Aptian to early Albian in the southern part of the Angola Basin which translated the previously formed oceanic crust and its overlying evaporite deposits on the South American side. Several ridge jumps occurred on both sides of Walvis Ridge during the Late Cretaceous and early Tertiary to produce a 500-km-long segment of mid-ocean ridge.

Initial Reports of the D.S.D.P.↗

USGS2014

Preliminary simulation of chloride transport in the Equus Beds aquifer and simulated effects of well pumping and artificial recharge on groundwater flow and chloride transport near the city of Wichita, Kansas, 1990 through 2008

The Equus Beds aquifer in south-central Kansas is a primary water-supply source for the city of Wichita. Water-level declines because of groundwater pumping for municipal and irrigation needs as well as sporadic drought conditions have caused concern about the adequacy of the Equus Beds aquifer as a future water supply for Wichita. In March 2006, the city of Wichita began construction of the Equus Beds Aquifer Storage and Recovery project, a plan to artificially recharge the aquifer with excess water from the Little Arkansas River. Artificial recharge will raise groundwater levels, increase storage volume in the aquifer, and deter or slow down a plume of chloride brine approaching the Wichita well field from the Burrton, Kansas area caused by oil production activities in the 1930s. Another source of high chloride water to the aquifer is the Arkansas River. This study was prepared in cooperation with the city of Wichita as part of the Equus Beds Aquifer Storage and Recovery project. Chloride transport in the Equus Beds aquifer was simulated between the Arkansas and Little Arkansas Rivers near the Wichita well field. Chloride transport was simulated for the Equus Beds aquifer using SEAWAT, a computer program that combines the groundwater-flow model MODFLOW-2000 and the solute-transport model MT3DMS. The chloride-transport model was used to simulate the period from 1990 through 2008 and the effects of five well pumping scenarios and one artificial recharge scenario. The chloride distribution in the aquifer for the beginning of 1990 was interpolated from groundwater samples from around that time, and the chloride concentrations in rivers for the study period were interpolated from surface water samples. Five well-pumping scenarios and one artificial-recharge scenario were assessed for their effects on simulated chloride transport and water levels in and around the Wichita well field. The scenarios were: (1) existing 1990 through 2008 pumping conditions, to serve as a baseline scenario for comparison with the hypothetical scenarios; (2) no pumping in the model area, to demonstrate the chloride movement without the influence of well pumping; (3) double municipal pumping from the Wichita well field with existing irrigation pumping; (4) existing municipal pumping with no irrigation pumping in the model area; (5) double municipal pumping in the Wichita well field and no irrigation pumping in the model area; and (6) increasing artificial recharge to the Phase 1 Artificial Storage and Recovery project sites by 2,300 acre-feet per year. The effects of the hypothetical pumping and artificial recharge scenarios on simulated chloride transport were measured by comparing the rate of movement of the 250-milligrams-per-liter-chloride front for each hypothetical scenario with the baseline scenario at the Arkansas River area near the southern part of the Wichita well field and the Burrton plume area. The scenarios that increased the rate of movement the most compared to the baseline scenario of existing pumping between the Arkansas River and the southern boundary of the well field were those that doubled the city of Wichita’s pumping from the well field (scenarios 3 and 5), increasing the rate of movement by 50 to 150 feet per year, with the highest rate increases in the shallow layer and the lowest rate increases in the deepest layer. The no pumping and no irrigation pumping scenarios (2 and 4) slowed the rate of movement in this area by 150 to 210 feet per year and 40 to 70 feet per year, respectively. In the double Wichita pumping scenario (3), the rate of movement in the shallow layer of the Burrton area decreased by about 50 feet per year. Simulated chloride rate of movement in the deeper layers of the Burrton area was decreased in the no pumping and no irrigation scenarios (2 and 4) by 80 to 120 feet per year and 50 feet per year, respectively, and increased in the scenarios that double Wichita’s pumping (3 and 5) from the well field by zero to 130 feet per year, with the largest increases in the deepest layer. In the increased Phase 1 artificial recharge scenario (6), the rate of chloride movement in the Burrton area increased in the shallow layer by about 30 feet per year, and decreased in the middle and deepest layer by about 10 and 60 feet per year, respectively. Comparisons of the rate of movement of the simulated 250-milligrams-per-liter-chloride front in the hypothetical scenarios to the baseline scenario indicated that, in general, increases to pumping in the well field area increased the rate of simulated chloride movement toward the well field area by as much as 150 feet per year. Reductions in pumping slowed the advance of chloride toward the well field by as much as 210 feet per year, although reductions did not stop the movement of chloride toward the well field, including when pumping rates were eliminated. If pumping is completely discontinued, the rate of chloride movement is about 500 to 600 feet per year in the area between the Arkansas River and the southern part of the Wichita well field, and 70 to 500 feet per year in the area near Burrton with the highest rate of movement in the shallow aquifer layer. The averages of simulated water-levels in index monitoring wells in the Wichita well field at the end of 2008 were calculated for each scenario. Compared to the baseline scenario, the average simulated water level was 5.05 feet higher for the no pumping scenario, 4.72 feet lower for the double Wichita pumping with existing irrigation scenario, 2.49 feet higher for the no irrigation pumping with existing Wichita pumping scenario, 1.53 feet lower for the double Wichita pumping with no irrigation scenario, and 0.48 feet higher for the increased Phase 1 artificial recharge scenario. The groundwater flow was simulated with a preexisting groundwater-flow model, which was not altered to calibrate the solute-transport model to observed chloride-concentration data. Therefore, some areas in the model had poor fit between simulated chloride concentrations and observed chloride concentrations, including the area between Arkansas River and the southern part of the Wichita well field, and the Hollow-Nikkel area about 6 miles north of Burrton. Compared to the interpreted location of the 250-milligrams per liter-chloride front based on data collected in 2011, in the Arkansas River area the simulated 250-milligrams per liter-chloride front moved from the river toward the well field about twice the rate of the actual 250-milligrams per liter-chloride front in the shallow layer and about four times the rate of the actual 250-milligrams per liter-chloride front in the deep layer. Future groundwater-flow and chloride-transport modeling efforts may achieve better agreement between observed and simulated chloride concentrations in these areas by taking the chloride-transport model fit into account when adjusting parameters such as hydraulic conductivity, riverbed conductance, and effective porosity during calibration. Results of the hypothetical scenarios simulated indicate that the Burrton chloride plume will continue moving toward the well field regardless of pumping in the area and that one alternative may be to increase pumping from within the plume area to reverse the groundwater-flow gradients and remove the plume. Additionally, the results of modeling these scenarios indicate that eastward movement of the Burrton plume could be slowed by the additional artificial recharge at the Phase 1 sites and that decreasing pumping along the Arkansas River or increasing water levels could retard the movement of chloride and may prevent further encroachment into the southern part of the well field area.

Kansas↗

USGS2010

A summary of information on the rust Puccinia psidii Winter (guava rust) with emphasis on means to prevent introduction of additional strains to Hawaii

The neotropical rust fungus Puccinia psidii ( P. psidii ) was originally described from the host common guava in its native Brazil but has been found since on hosts throughout the myrtle family (Myrtaceae), including a dramatic host jump to nonnative Eucalyptus plantations. Most rust fungi are able to live only on a very narrow range of host species. P. psidii is unusual both for having a broad host range and for the intensity of its damage to susceptible young growth. This rust first got a foothold in the United States in Florida more than three decades ago. The U.S. Department of Agriculture (USDA) has since considered it a nonactionable, nonreportable pest. Hawaii and Florida are the only two states with native species in the myrtle family. Over a period of 30 years, this rust has done little damage to any of the scattered native Myrtaceae in Florida, although the host range of the rust has gradually grown to about 30 mostly nonnative species in the family, apparently because of increasing genetic variety of the rust by repeated introductions. However, Florida’s native Myrtaceae are among the roughly 1,100 neotropical species that are largely resistant to P. psidii . The 3,000 species of non-neotropical Myrtaceae of the Pacific, Australia, Asia, and Africa are expected to prove much more vulnerable to P. psidii . Little is known about the genetics or genetic strains of P. psidii , although existing literature shows that there are numerous strains that have differential ability to infect suites of host plants. The rust was first recorded in the state of Hawaii on Oahu in April 2005 and quickly spread throughout the Hawaiian Islands. The main concern in Hawaii became the potential threat to ohia, Metrosideros polymorpha (Myrtaceae), the endemic forest tree species overwhelmingly important in Hawaii’s nature and culture. The potential ecological consequences of a virulent strain of rust on ohia forests are immense, due to its role as a foundation tree species and the diversity of niches it fills in Hawaii. A single genetic strain of the rust is established in Hawaii, apparently composed of a single genotype lacking sexual reproduction. P. psidii has been found statewide in Hawaii attacking Myrtaceae from near sea level to about 1,200 m elevation in areas with rainfall ranging from 750–5,000 mm. Five of eight native Myrtaceae and at least 15 nonnative species have been observed as hosts of P. psidii in Hawaii. The federally endangered Eugenia koolauensis (nioi) and the nonendangered indigenous species Eugenia reinwardtiana are severely damaged. The introduced (an Asian species) and invasive rose apple, Syzygium jambos , is severely affected at a landscape scale, with widespread crown dieback and many instances of complete tree death. In spite of billions of wind-dispersed rust spores produced from rose apple infestations during 2006 to 2008, adjacent ohia have been little affected to date by the rust strain in Hawaii. Within the elevation range of the rust, P. psidii is found on less than 5 percent of the ohia trees in the wild; on those ohia trees on which the rust is found, it is normally found on less than 5 percent of the leaves. The strain in Hawaii has not attacked many of the species known to be infected by the rust elsewhere, including common guava. On the basis of the very substantial genetic diversity of the much-studied, crop-damaging species of the genus Puccinia , there is good reason to believe that there are at minimum dozens and likely hundreds or thousands of genotypes of P. psidii , likely concentrated in the core range in Brazil but with potential for dispersal by globalization. Multiple genotypes are believed already present in the United States and certain to spread freely in the absence of restrictions. The U.S. Forest Service has initiated a major collaborative project in Brazil to investigate the genetics of susceptibility of Hawaii’s ohia to P. psidii , but initial results will likely not be available for several years. If just one more strain reaches Hawaii, the consequences could be dire for ohia, with each new genotype arriving having an unknown likelihood of increasing damage to ohia; possibilities for mutation and (or) genetic mixing, even with asexual strains, are apparently substantial, based on what is known about other Puccinia species. Investigations are needed to clarify rust-nioi relationships. However, it is likely that keeping out new strains of P. psidii may be important for long-term survival of nioi as well as for the health of ohia forest. The source of Hawaii’s initial invasion by P. psidii is uncertain but is strongly suspected to have been decorative foliage of species in the myrtle family from the mainland United States, most likely California, where there had been outbreaks of this rust on cultivated myrtle in 2005. In 2006–7, Maui’s Hawaii Department of Agriculture (HDOA) inspectors intercepted several P. psidii infected shipments of foliage myrtle, shipped from several California counties. Recognizing the huge threat of the rust to Hawaii’s one million acres of ohia forests, and consequently to Hawaii’s watersheds and biodiversity, Hawaii’s Board of Agriculture unanimously approved an interim rule in August 2007 banning importation of plants in the myrtle family from “infested areas,” specified as South America, Florida, and California. However, the interim rule has not been made permanent by HDOA, and the department has stated that it needs further information to formulate a long-term rule that imposes appropriate measures. Rust spores can survive for 2 to 3 months, and the pathogen can be transported to Hawaii on Myrtaceae from anywhere in the world through the United States mainland. There is much geographic reshuffling of flowers and foliage among the far-flung firms in the trade, especially for bouquet making. Because P. psidii is a nonactionable and nonreportable pest in the United States, foliage and flowers of the myrtle family can move freely into the country (usually but not necessarily always through the ports of Miami or Los Angeles), and from state to state. Currently, the State of Hawaii regulates incoming plant material in the family Myrtaceae by visual inspection. Inspection capacity and latent (asymptomatic) infections limit the ability to detect the rust. New molecular tests could improve detection efficiency, but the cost and the time required to process samples currently precludes their routine use in ports of entry. Interdiction, which has effectively kept coffee rust ( Hemileia vastatrix ) out of Hawaii for 120 years, offers the strongest protection for Hawaii’s native ecosystems from P. psidii . Interdiction of Myrtaceae from the continental United States could have the important supplementary benefit of preventing establishment in Hawaii of other very significant pests of multiple species of Myrtaceae that are already in the country, including: the Eugenia psyllid Trioza eugeniae (Hemiptera: Psyllidae); Chrysophtharta m-fuscum , the Eucalyptus tortoise beetle (Coleoptera: Chrysomelidae); Leptocybe invasa , the blue gum chalcid wasp (Hymenoptera: Chalcidae); and the fungal pathogens Mycosphaerella molleriana (Ascomycota: Mycosphaerelliaceae, crinkle leaf disease of Eucalyptus spp.) and Neofusicoccum parvum (Ascomycota: Botryosphaeriaceae), currently causing serious damage to Syzygium paniculatum in south Florida nurseries. Each of these pests would be likely to cause very significant damage to native and (or) cultivated Myrtaceae in Hawaii. Each of these pests is a prime candidate for transport by the foliage and (or) nursery stock pathways from Florida and California into Hawaii. Hawaii Department of Agriculture has a clear mandate to protect Hawaii’s natural environment, forestry and cultivated Myrtaceae. Principles of the World Trade Organization’s Treaty on Sanitary and Phytosanitary Measures and the International Plant Protection Convention are consistent with the right of Hawaii to take action. The current threat of P. psidii and the other five serious threats to Myrtaceae are primarily posed by the importation of infected plants from the continental United States; however, that may change in the future. If Hawaii were to decide to take a stand (through State regulation) to protect its native and introduced Myrtaceae, there is a possibility that USDA would consider Federal regulation of Myrtaceae from foreign countries.

Hawaii↗

USGS2013

Hydrology and water quality of Shell Lake, Washburn County, Wisconsin, with special emphasis on the effects of diversion and changes in water level on the water quality of a shallow terminal lake

Shell Lake is a relatively shallow terminal lake (tributaries but no outlets) in northwestern Wisconsin that has experienced approximately 10 feet (ft) of water-level fluctuation over more than 70 years of record and extensive flooding of nearshore areas starting in the early 2000s. The City of Shell Lake (City) received a permit from the Wisconsin Department of Natural Resources in 2002 to divert water from the lake to a nearby river in order to lower water levels and reduce flooding. Previous studies suggested that water-level fluctuations were driven by long-term cycles in precipitation, evaporation, and runoff, although questions about the lake’s connection with the groundwater system remained. The permit required that the City evaluate assumptions about lake/groundwater interactions made in previous studies and evaluate the effects of the water diversion on water levels in Shell Lake and other nearby lakes. Therefore, a cooperative study between the City and U.S. Geological Survey (USGS) was initiated to improve the understanding of the hydrogeology of the area and evaluate potential effects of the diversion on water levels in Shell Lake, the surrounding groundwater system, and nearby lakes. Concerns over deteriorating water quality in the lake, possibly associated with changes in water level, prompted an additional cooperative project between the City and the USGS to evaluate efeffects of changes in nutrient loading associated with changes in water levels on the water quality of Shell Lake. Numerical models were used to evaluate how the hydrology and water quality responded to diversion of water from the lake and historical changes in the watershed. The groundwater-flow model MODFLOW was used to simulate groundwater movement in the area around Shell Lake, including groundwater/surface-water interactions. Simulated results from the MODFLOW model indicate that groundwater flows generally northward in the area around Shell Lake, with flow locally converging toward the lake. Total groundwater inflow to Shell Lake is small (approximately 5 percent of the water budget) compared with water entering the lake from precipitation (83 percent) and surface-water runoff (13 percent). The MODFLOW model also was used to simulate average annual hydrologic conditions from 1949 to 2009, including effects of the removal of 3 billion gallons of water during 2003–5. The maximum decline in simulated average annual water levels for Shell Lake due to the diversion alone was 3.3 ft at the end of the diversion process in 2005. Model simulations also indicate that although water level continued to decline through 2009 in response to local weather patterns (local drought), the effects of the diversion decreased after the diversion ceased; that is, after 4 years of recovery (2006–9), drawdown attributable to the diversion alone decreased by about 0.6 ft because of increased groundwater inflow and decreased lake-water outflow to groundwater caused by the artificially lower lake level. A delayed response in drawdown of less than 0.5 ft was transmitted through the groundwater-flow system to upgradient lakes. This relatively small effect on upgradient lakes is attributed in part to extensive layers of shallow clay that limit lake/groundwater interaction in the area. Data collected in the lake indicated that Shell Lake is polymictic (characterized by frequent deep mixing) and that its productivity is limited by the amount of phosphorus in the lake. The lake was typically classified as oligotrophic-mesotrophic in June, mesotrophic in July, and mesotrophic-eutrophic in August. In polymictic lakes like Shell Lake, phosphorus released from the sediments is not trapped near the bottom of the lake but is intermittently released to the shallow water, resulting in deteriorating water quality as summer progresses. Because the productivity of Shell Lake is limited by phosphorus, the sources of phosphorus to the lake were quantified, and the response in water quality to changes in phosphorus inputs were evaluated by means of eutrophication models. During 2009, the total input of phosphorus to Shell Lake was 1,730 pounds (lb), of which 1,320 lb came from external sources (76 percent) and 414 lb came from internal loading from sediments in the lake (24 percent). The largest external source was from surface-water runoff, which delivered about 52 percent of the total phosphorus load compared with about 13 percent of the water input. The second largest source was from precipitation (wetfall and dryfall), which delivered 19 percent of the load compared to about 83 percent of the water input. Contributions from septic systems and groundwater accounted for about 3 and 2 percent, respectively. Increased runoff raises water levels in the lake but does not necessarily increase phosphorus loading because phosphorus concentrations in the tributaries decline during increased flow, possibly because of shorter retention times in upstream wetlands. Phosphorus loading to the lake in 2009 represented what occurred after a series of dry years; therefore, this information was combined with data from 2011, a wet year, to estimate phosphorus loading during a range of hydrologic conditions by estimating loading from each component of the phosphorus budget for each year from 1949 to 2011. Comparisons of historical water-quality records with historical water levels and applications of a hydrodynamic model (Dynamic Lake Model, DLM) and empirical eutrophication models were used to understand how changes in water level and the coinciding changes in phosphorus loading affect the water quality of Shell Lake. DLM simulations indicate that large changes in water level (approximately 10 ft) affect the persistence of stratification in the lake. During periods with low water levels, the lake is a well-mixed, polymictic system, with water quality degrading slightly as summer progresses. During periods with high water levels, the lake is more stratified, and phosphorus from internal loading is trapped in the hypolimnion and released later in summer, which results in more extreme seasonality in water quality and better clarity in early summer. Results of eutrophication model simulations using a range in external phosphorus inputs illustrate how water quality in Shell Lake (phosphorus and chlorophyll a concentrations and Secchi depths) responds to changes in external phosphorus loading. Results indicate that a 50-percent reduction in external loading from that measured in 2009 would be required to change phosphorus concentrations from 0.018 milligram per liter (mg/L) (measured in 2009) to 0.012 mg/L (estimated for the mid-1800s from analysis of diatoms in sediment cores). Such reductions in phosphorus loading cannot be accomplished by targeting septic systems or internal loading alone because septic systems contribute only about 3 percent of the phosphorus input to the lake, and internal loading from the sediments of Shell Lake contributes only about 25 percent of phosphorus input. Complete elimination of phosphorus from septic systems and internal loading would decrease the phosphorus concentrations in the lake by 0.003–0.004 mg/L. Therefore, reducing phosphorus concentration in the lake more than by 0.004 mg/L requires decreasing phosphorus loading from surface-water contributions, primarily runoff to the lake. Reconstructed changes in water quality from 1860 to 2010, based on changes in the diatom communities archived in the sediments and eutrophication model simulations, suggest that anthropogenic changes in the watershed (sawmill construction in 1881; the establishment of the village of Shell Lake; and land-use changes in the 1920s, including increased agriculture) had a much larger effect on water quality than the natural changes associated with fluctuations in water level. Although the effects of natural changes in water level on water quality appear to be small, changes in water level do have a modest effect on water quality, primarily manifested as small improvements during higher water levels. Fluctuations in water level, however, have a larger effect on the seasonality of water-quality patterns, with better water quality, especially increased Secchi depths, in early summer during years with high water levels.

Wisconsin↗

USGS2021

Evaluation of larval lamprey survival following salvage: A pilot study

Larval lampreys ( Entosphenus tridentatus and Lampetra spp.) are vulnerable to anthropogenic water-level fluctuations that can dewater their habitat. Dewatering events occur regularly in the Columbia River Basin for operation and management of hydropower facilities, seasonal or maintenance closures of irrigation diversions, and in-water construction projects, including for habitat restoration. Salvage efforts which can be initiated before, during, and after dewatering events are resource-intensive and are conducted based on the assumption that salvage will reduce lamprey mortality. This pilot study was the first formal assessment of the efficacy of salvage efforts, evaluating the survival and performance of larval lamprey following various salvage techniques. Lampreys were salvaged during dewatering events at three field sites under variable environmental conditions (summer and fall of 2020) and then held in the laboratory for 60 days to monitor survival, growth, and burrowing performance. Four salvage treatments were defined to represent combinations of typical salvage techniques and stressors, including multiple passes of standard electrofishing (SEF), lamprey-specific electrofishing (LEF), and modified lamprey-specific electrofishing (MLEF; probes in direct contact with dewatered, but moist substrate) as well as extended exposure on the surface and walking on sediment where lampreys were burrowed. Control groups did not experience dewatering and were collected using LEF in areas away from treatment groups. Treatments were designed to increase in intensity, from treatment 1 (walking and exposure) to treatment 4 (multiple passes of SEF, LEF and MLEF). Study sites included an earthen hatchery rearing pond (North Toutle Hatchery) dewatered in July, and two irrigation diversions (Wapato and Sunnyside diversions on Yakima River) dewatered at the end of the irrigation season in October. Treatments were executed inside circular 1 m2 enclosures that were randomly positioned in habitats expected to be dewatered. A solid, weighted ring at the bottom of the enclosure penetrated the sediment and netting extended through the water column to a floating upper ring. We deployed eight enclosures per treatment at each test site, executed the four salvage treatments, collected lamprey from within each enclosure and transported them to the laboratory, along with the control groups, for the 60-day holding period. Burrowing performance was tested in sand 1 day after the field effort and in field-collected sediment 30 days after the field effort. Mortality was documented and lamprey were measured at 1, 30, and 60 days in the laboratory and fish weights were used to calculate standard growth rate (SGR) for each site and treatment group. We collected 328 larval lampreys at our three test sites, including 71 controls and 257 larvae exposed to dewatering and salvage treatments. Overall mortality for the 60-day laboratory holding period was 11.9%. Most mortality occurred within 1-day after treatment (51.3%) and there was limited mortality past 30 days (2.6%). At the North Toutle Hatchery, we observed substantial mortality during the field tests in July, both inside and outside of our test enclosures. Mortality within our test enclosures ranged from 96.7 to 98.8% for treatment 1, 45.9 to 52.2% for treatment 3 and 6.7 to 7.1% for treatment 4. The elevated mortality at this site and logistical challenges with the execution of treatments 1 and 2 resulted in few fish (5 total for treatment 1) or no fish (treatment 2) available for testing in the laboratory. Only one larval lamprey died during field tests at the Wapato and Sunnyside irrigation diversions during testing in October. The single mortality was in treatment 1 (11.1%) and no mortalities were observed outside of the test enclosures. We used logistic regression to estimate survival of larval lampreys transported to the laboratory and held for 24 h. The Wapato and Sunnyside field sites were pooled for logistic regression and the North Toutle Hatchery site was analyzed separately due to dramatically different environmental conditions. We found that treatment 1 reduced larval survival more than any other treatment during both the summer and fall dewatering events. Trends among survival for treatments 2-4 were less clear. The unique stressor included in the first treatment, but not in other treatments, was a 2-hour exposure period during which larvae were left lying on the surface of the sediment. Treatment 1 also experienced a walking action (foot pressure on the surface of the exposed sediment). The walking action was also included in treatment 4, both before and after dewatering, along with multiple passes of various electrofishing techniques, as this treatment was designed to be a worst-case scenario for lamprey salvage. Despite what appeared to be significant stressors associated with treatment 4, the logistic regression for survival up to 24 hours in the laboratory showed that the odds of surviving treatment 4 were 16 times higher than the odds of surviving treatment 1 at Wapato and Sunnyside (combined). The same comparison at the North Toutle Hatchery showed the odds were 226 times higher for lamprey to survive treatment 4 compared to treatment 1. Lamprey from all study sites initiated burrowing activity with median times less than 10.5 seconds in both sand (day 1) and field-collected sediment (day 30). The fastest burrowing start times were less than 1.0 second and the slowest was 3.2 minutes. Lamprey behavioral responses during burrowing ability tests were variable. Some lampreys immediately moved from the release location near the surface of the water toward the sediment and began burrowing while others swam around the aquarium near the surface of the water before exploring the sediment to select a burrowing location. The median time to complete burrowing for all treatment groups and sample periods ranged from 9.9 to 48.1 seconds. No significant differences in SGR were detected between treatment and control groups at any test site. Laboratory water temperatures for the North Toutle Hatchery study groups were maintained at 15°C, giving lamprey a growth advantage compared to the Wapato and Sunnyside groups which were maintained at 10℃. SGR for lamprey collected at the North Toutle Hatchery ranged from 0.83% weight gain/day for controls to 2.04%/day for treatment 3. SGR at Wapato ranged from 0.27 to 0.67%/day and from 0.60 to 0.90 %/day at Sunnyside. Overall, SGR was consistently lower at every site for the controls compared to any of the treatment groups, although none of the differences were significant. The variability at some sites in initial lamprey size, combined with inherent variability in growth rates, limited our ability to make conclusions about how different salvage treatments influenced SGR. Treatment 1 stood out among the salvage treatments at all study sites. In this treatment, lampreys exposed on the surface of the sediment, awaiting salvage, were vulnerable to reduced survival, even under mild environmental conditions. The risk of mortality was greatest for the summer dewatering event at the North Toutle Hatchery. The remaining treatments, even with multiple passes of various electrofishing techniques, did not generally have large negative impacts on lamprey during our tests. Lamprey survival rates for these treatments were relatively high, especially at the fall dewatering sites when environmental conditions were mild. Thus, salvage efforts, despite being resource intensive, likely have limited negative outcomes for larval lamprey and make substantial contributions to lamprey conservation efforts.

Report↗

USGS1967

Effects of the earthquake of March 27, 1964, at Seward, Alaska

Seward, in south-central Alaska, was one of the towns most devastated by the Alaska earthquake of March 27, 1964. The greater part of Seward is built on an alluvial fan-delta near the head of Resurrection Bay on the southeast coast of the Kenai Peninsula. It is one of the few ports in south-central Alaska that is ice free all year, and the town’s economy is almost entirely dependent upon its port facilities. The Alaska earthquake of March 27, 1964, magnitude approximately 8.3–8.4, began at 6:36 p.m. Its epicenter was in the northern part of the Prince William Sound area; focal depth was 20–50 km. Strong ground motion at Seward lasted 3–4 minutes. During the shaking, a strip of land 50–400 feet wide along the Seward waterfront, together with docks and other harbor facilities, slid into Resurrection Bay as a result of large-scale submarine landsliding. Fractures ruptured the ground for'severa1 hundred feet back from the landslide scarps. Additional ground was fractured in the Forest Acres subdivision and on the alluvial floor of the Resurrection River valley; fountaining and sand boils accompanied the ground fracturing. Slide-generated wares, possibly seiche waves, and seismic sea waves crashed onto shore; ware runup was as much as 30 feet above mean lower low water and caused tremendous damage; fire from burning oil tanks added to the destruction. Damage from strong ground motion itself was comparatively minor. Tectonic subsidence of about 3.6 feet resulted in low areas being inundated at high tide. Thirteen people were killed and five were injured as a result of the earthquake. Eighty-six houses were totally destroyed and 260 were heavily damaged. The harbor facilities were almost completely destroyed, and the entire economic base of the town was wiped out. The total cost to replace the destroyed public and private facilities was estimated at $22 million. Seward lies on the axis of the Chugach Mountains geosyncline. The main structural trend in the mapped area, where the rocks consist almost entirely of graywacke and phyllite, is from near north to N. 20° E. Beds and cleavage of the rocks commonly dip 70° W. or NW. to near vertical. Locally, the rocks are complexly folded or contorted. So major faults were found in the mapped area, but small faults, shear zones, and joints are common. Surficial deposits of the area hare been divided for mapping into the following units: drift deposits, alluvial fan deposits, valley alluvium, intertidal deposits, landslide deposits, and artificial fill. Most of these units intergrade and were deposited more or less contemporaneously. The drift deposits consist chiefly of till that forms moraines along the lower flanks of the Resurrection River valley and up tributary valleys. The till is predominantly silt and sand and lesser amounts of clay-size particles, gravel, cobbles, and boulders. Glacial outwash and stratified ice-contact deposits constitute the remainder of the drift deposits. Fans and fan-deltas have been deposited at the valley mouths of tributary streams. Some, including the one upon which Seward built, project into Resurrection Bay, and deltaic-type deposits form their distal edges. The larger fans—composed chiefly of loosely compacted and poorly sorted silt, sand, and gravel—form broad aprons having low gradients. The fan deposits range in thickness from about 100 feet to possibly several hundred feet and, at least in some places, lie on a platform of compact drift. Smaller fans at the mouths of several canyons have steep gradients and considerable local relief. Valley alluvium, deposited chiefly by the Resurrection River, consists mostly of coarse sand and fine to medium gravel. In the axial part of the valley it is probably more than 100 feet thick. Near the head of Resurrection Bay, the alluvium is underlain by at least 75 feet of marine deltaic sediments, which are in turn underlain by 600 or more feet of drift in the deepest part of the bedrock valley. Beach, deltaic, and estuarine sediments, deposited on intertidal flats at the head of the bay and along far1 margins that extend into the bay, arc mapped as intertidal deposits. They consist mostly of silt, sand, and fine gravel, and lesser amounts of clay-size particles. The earthquake reactivated old slides and trigged new ones in the mountains. Rock and snow avalanches, debris flows, and creep of talus deposits characterized slide activity on the steeper slops. The Seward waterfront had been extended before the earthquake by adding artificial fill consisting of loose sand and gravel; part of the lagoon area had been filled with refuse. After the earth- quake, fill, consisting of silt and sand dredged from the head of the bay, was pumped onto part of the lagoon area and also on land at the northwest corner of the bay. Response to the disaster was immediate and decisive. City, State, and Federal agencies, as well as other organizations and individuals, gave unstintingly of their time and facilities. Within a few days, there was temporary restoration of water, sewerage, and electrical facilities. The U.S. Army Corps of Engineers was authorized to select sites and construct a new dock for the Alaska Railroad, a new small-boat basin, and related facilities. The firm of Shannon and Wilson, Inc., under contract to the Corps of Engineers, investigated subsurface soils extensively to determine the factors responsible for the sliding along the Seward waterfront and to assist in site selection for reconstruction of the destroyed harbor facilities. Borings also made along the Seward waterfront and at the head of the bay, and laboratory tests were conducted on pertinent samples. These studies were augmented by geophysical studies both on land and in the bay. In addition, the Corps of Engineers made shallow borings on the intertidal flats at the head of the bay and performed pile-driving and load tests. Borings also were drilled and test pits were dug in the subdivision of Forest Acres. Sliding along the Seward waterfront markedly deepened the water along the former shoreline. Post-earthquake slopes of the bay floor immediately offshore also are steeper in places than before the earthquake. The strong ground motion of the earthquake triggered the landsliding, but several factors may have contributed to the magnitude and characteristics of the slides. These factors are: (1) the long duration of strong ground motion, (2) the grain size and texture of the material involved in the sliding, (3) the probability that the finer grained materials liquefied and flowed seaward, and (4) the added load of manmade facilities built on the edge of the shore, Secondary effects of the slides themselves—sudden drawdown of water, followed by the weight of returning waves—also may have contributed to the destruction. Submarine sliding at the northwest corner of the bay occurred in fine-grained deltaic deposits whose frontal slopes probably were in metastable equilibrium under static conditions. Uplift pressures from aquifers under hydrostatic head, combined with the probable liquefaction characteristics of the sediments when vibrated by strong ground motion, probably caused the material to slide and flow seaward as a heavy slurry. Under static conditions, no major shoreline or submarine landsliding is expected in the Seward area; in the event of another severe earthquake, however, additional sliding is likely along the Seward waterfront and also in the deltaic deposits at the northwest corner of the bay. Fractured ground in back of the present shoreline along the Seward waterfront is an area of incipient landslides that would be unstable under strong shaking. For this reason the Scientific and Engineering Task Force placed the area in a high-risk classification and recommended no repair, rehabilitation, or new construction in this area involving use of Federal funds; it was further recommended that the area should be reserved for park or other uses that do not involve large congregations of people. The deltaic deposits at the head of the bay probably also would be susceptible to sliding during another large earthquake. This sliding would result in further landward retreat of the present shoreline toward the new railroad dock. Specifications for the new dock, whose seaward end is now approximately 1,100 feet from the back scarp of the subaqueous landslide, require design pro- visions to withstand seismic shock up to certain limits. Earthquake-induced fracturing of the ground in the subdivision of Forest Acres was confined to the lower part of a broad alluvial fan. There, sewer and water lines were ruptured and the foundations of some homes were heavily damaged. Landsliding, such as occurred along the shoreline of the bay, was not a contributing cause of the fracturing. Two hypotheses are offered to explain the fracturing: 1. Seismic energy was transformed into visible surface waves of such amplitude that the strength of surface layer was exceeded and rupturing occurred; tensional and compressional stresses alternately opened and closed the fractures and forced out water and mud. 2. Compaction by vibration of the fine-grained deposits of the fan caused ground settlement and fracturing; ground water under temporary hydrostatic head was forced to the surface as fountains and carried the finer material with it. Water waves that crashed onto shore, while shaking was still continuing, were generated chiefly by onshore and offshore landsliding. Waves that overran the shores about 25 minutes after shaking stopped and that continued to arrive for the next several hours are believed to be seismic sea waves (tsunamis) that originated in an uplifted area in the Gulf of Alaska. During the time of seismic sea-wave activity and perhaps preceding it, seiche wares also may have been generated within Resurrection Bay and complicated the wave effects along the shoreline.

Alaska↗

USGS2022

Distribution and demography of Coastal Cactus Wrens in Southern California, 2015–19

Surveys and monitoring for the coastal Cactus Wren ( Campylorhynchus brunneicapillus ) were completed in San Diego County between March 2015 and July 2019. A total of 383 plots were surveyed across 3 genetic clusters (Otay, Lake Jennings, and Sweetwater/Encanto). From 2015 to 2019, 317 plots were surveyed 8 times (twice per year in 2015, 2017–19). Additional plots were added in later years as wrens were discovered in new locations. We found differences in the proportion of plots occupied in the genetic clusters, with a lower proportion of plots occupied in the Otay cluster than in the Lake Jennings and Sweetwater/Encanto clusters in all years. Plot occupancy increased each year in the Otay and Sweetwater/Encanto clusters but not in the Lake Jennings cluster. The number of Cactus Wren territories increased from 2015 through 2018, and then decreased in 2019 in all three genetic clusters. We monitored nesting activities for two populations of Cactus Wrens in southern San Diego County. The Otay population consisted of two sites within the Otay genetic cluster, and the San Diego population consisted of two sites within the Sweetwater/Encanto and Lake Jennings genetic clusters. Nest monitoring occurred at 10–13 territories per year in the Otay population and 14–18 territories in the San Diego population from 2015 through 2019. All territories were occupied by pairs except two territories in 2015, five in 2016, and two in 2019. Between 46 and 74 Cactus Wren nests were monitored each year, which totaled 295 monitored nests from 2015 to 2019. To evaluate the direct influence of precipitation on breeding success, bio-year precipitation (“precipitation”) was calculated from July 1 of the prior year through June 30 of the breeding season year. Overall apparent nest success was positively influenced by precipitation with the lowest apparent nest success of 50 percent in 2015 and the highest apparent nest success of 72 percent in 2017, corresponding to the second lowest and the highest precipitation years, respectively. Apparent nest success also was higher in the Otay population than in the San Diego population. The number of brood nests initiated per pair and the number of renesting attempts per pair also were higher in years with more precipitation. Other metrics of Cactus Wren nesting success and productivity were positively influenced by the amount of precipitation, including clutch size and egg hatching success. The percent of hatchlings that fledged was greater in the Otay population than in the San Diego population but was not influenced by precipitation. The number of fledglings per pair was higher in years with more precipitation and was greater in the Otay population than in the San Diego population. Predation was the predominant cause of nest failure in both populations. Analysis of Cactus Wren daily nest survival rate indicated that there was a population, and possibly a precipitation effect on nest survival, with the daily survival rate for the Otay population significantly higher than for the San Diego population and weak increase in the daily survival rate with more precipitation. A total of 629 Cactus Wrens were banded during the course of the study, 360 in the San Diego population and 269 in the Otay population. Between 2015 and 2019, we resighted 301 color-banded adult birds that ranged between 1 and 8 years old. One additional color-banded bird was resighted in San Pasqual Valley (as part of a separate study); this bird originated in the San Diego population and was excluded from our analyses. Annual survival was higher for adult Cactus Wrens (ranging from 60 to 70 percent) than for first-year wrens (ranging from 20 to 28 percent) and varied by year. Annual survival was also weakly but positively correlated with precipitation. Annual survival was higher for first year and adult Cactus Wrens following years with increased precipitation. We found no evidence that survival differed by population. Banding also allowed us to examine whether there were differences in movement of adult and first-year Cactus Wrens by year or by population. We found that average dispersal distance for first-year Cactus Wrens was 1.9 kilometers in the Otay population and 1.6 kilometers in the San Diego population and did not differ by population or year. Dispersal between populations was not common. We detected five instances of movement of first-year wrens between the San Diego and Otay populations. All movements into and out of the San Diego population were from or into territories in the Sweetwater area. We detected no movement between the Lake Jennings site and either of the Sweetwater or Otay sites; however, we did detect one wren that dispersed from Lake Jennings to the San Pasqual Valley population in 2019, which was a distance of 26.4 kilometers. Adult Cactus Wrens were site-faithful, with 87 percent of adults remaining on the same territory between breeding seasons. Precipitation may be a weak driver of movement for adult Cactus Wrens, with adults more likely to remain on the same territory following years of increased precipitation. There was no difference in adult movement between populations. Arthropods were collected in pitfall traps and by vacuum in 23 Cactus Wren territories during 3 sampling periods in 2016 (early nesting, peak nesting, and late nesting). Arthropods of 19 orders and at least 128 families were collected. Analysis of 43 Cactus Wren fecal samples identified 10 arthropod orders that were present in more than 10 percent of fecal samples. The most abundant arthropod order collected was Hymenoptera; however, Cactus Wrens consumed arthropods in the order Hymenoptera significantly less than their availability, suggesting that this order was avoided. No other orders were significantly selected or avoided; however, selection indices of arthropod families identified that two families of arthropods (Isopoda Porcellionidae [woodlice] and Hymenoptera Formicidae [ants]) were avoided. After excluding the taxa that were avoided or not represented in fecal samples, 95 percent of Cactus Wren prey items were collected in pitfall traps and 5 percent were collected by vacuum. The most abundant prey orders captured were Diptera, Coleoptera, Hemiptera, Hymenoptera, and Aranea. Analysis of the abundance of Cactus Wren prey items by vegetation type and sampling period indicated that vegetation type by itself was not a significant predictor of arthropod abundance but interacted with sampling period. Seasonal availability of arthropods was highest in the peak nesting period, followed by early and late nesting periods for California sagebrush ( Artemisia californica ), lemonadeberry ( Rhus integrifolia ), non-native grass, and bare ground, whereas availability increased from early to late nesting periods for blue elderberry ( Sambucus mexicana spp. caerulea ), cactus ( Opuntia spp. and Cylindropuntia spp.), California buckwheat ( Eriogonum fasciculatum ), native bunch grasses, and black mustard ( Brassica nigra ). During the early nesting period, arthropods were most abundant in native bunch grasses and least abundant in lemonadeberry. During the peak nesting period, arthropods were most abundant in native bunch grasses and in areas of bare ground and were least abundant in cactus and blue elderberry. During late nesting, arthropods were most abundant in blue elderberry and non-native grass and least abundant in lemonadeberry and mustard. Each year from 2015 to 2019, vegetation data were collected at the same 23 territories where arthropods were sampled: 9 territories in the Otay population and 14 territories in the San Diego population. Cactus, California buckwheat, and non-native grasses were detected within at least 60 percent of sampling points in the Otay population. Cactus, California sagebrush, California buckwheat, non-native grass, and black mustard each were detected within an average of 40 percent of sampling points in the San Diego population. No native bunch grass or lemonadeberry were recorded at the Lake Jennings site within the San Diego population. The cover of shrub species was relatively stable throughout the 5 years. Cover of herbaceous species and bare ground had greater annual variation than shrub species. We found that vegetation cover varied widely among territories, with territory accounting for 69 percent of the variation in vegetation cover. Redundancy analysis allowed us to identify the vegetation types that accounted for the most variation. We used the top scores from the redundancy analysis to identify six vegetation types to be used in generalized linear mixed models analyzing the relationships between vegetation type, precipitation, and Cactus Wren breeding productivity. Three vegetation variables influenced the number of fledglings produced per pair. California sagebrush had a positive effect on the number of fledglings per pair whereas non-native grass and black mustard had a negative effect. Breeding productivity, survival, and movements of adult and first-year Cactus Wrens indicated that the Otay population behaved similarly to, if not out-performed, the San Diego population during the span of our project, suggesting that the driving forces behind low numbers of Cactus Wrens in the Otay population before 2015 were no longer in effect. The Cactus Wren populations in Otay and San Diego reached a peak in 2018, which followed a year of high productivity and survivorship, both of which were correlated with high precipitation. This peak in population size was consistent with reproductive timing and productivity in other bird populations in semi-arid ecosystems that were linked to precipitation and arthropod abundance. We did not find a strong link among arthropod abundance, vegetation composition, and Cactus Wren breeding productivity, likely in part because arthropod abundance varied by vegetation type and sampling period, suggesting that different vegetation types provided important sources of prey at different periods of the breeding season. Arthropod abundance also may not represent arthropod availability when vegetation structure discourages the ground foraging behavior of species such as Cactus Wrens. Cover of non-native grass negatively influenced breeding productivity, although arthropods were abundant in non-native grass. Other factors that could have influenced differential breeding productivity between the Otay and San Diego populations were habitat restoration, control of annual herbaceous vegetation, human disturbance, lingering effects of wildfire, and nest predation. Overall, precipitation appeared to be a driver of Cactus Wren breeding productivity and possibly survival, potentially obscuring proximate effects of arthropod or vegetation composition.

California↗