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At least 1,099 records · Page 61Linked to original sources

USGS1999

Influence of infection with Renibacterium salmoninarum on susceptibility of juvenile spring chinook salmon to gas bubble trauma

During experiments in our laboratory to assess the progression and severity of gas bubble trauma (GBT) in juvenile spring chinook salmon Oncorhynchus tshawytscha , we had the opportunity to assess the influence of Renibacterium salmoninarum (Rs), the causative agent of bacterial kidney disease, on the susceptibility of salmon to GBT. We exposed fish with an established infection of Rs to 120% total dissolved gas (TDG) for 96 h and monitored severity of GBT signs in the fins and gills, Rs infection level in kidneys by using an enzyme-linked immunosorbent assay (ELISA), and mortality. Mortality occurred rapidly after exposure to 120% TDG, with a LT20 (time necessary to kill 20% of the population) of about 37 h, which is at a minimum about 16% earlier than other bioassays we have conducted using fish that had no apparent signs of disease. Fish that died early (from 31 to 36 h and from 49 to 52 h) had significantly higher infection levels (mean ?? SE ELISA absorbance = 1.532 ?? 0.108) than fish that survived for 96h (mean ?? SE ELISA absorbance = 0.828 ?? 0.137). Fish that died early also had a significantly greater number of gill filaments occluded with bubbles than those that survived 96 h. Conversely, fish that survived for 96 h had a significantly higher median fin severity ranking than those that died early. Our results indicate that fish with moderate to high levels of Rs infection are more vulnerable to the effects of dissolved gas supersaturation (DGS) and die sooner than fish with lower levels of Rs infection. However, there is a substantial amount of individual variation in susceptibility to the apparent cumulative effects of DGS and Rs infection. Collectively, our findings have important implications to programs designed to monitor the prevalence and severity of GBT in juvenile salmonids in areas like the Columbia River basin and perhaps elsewhere.

Journal of Aquatic Animal Health↗

USGS2001

Summer habitat use by Columbia River redband trout in the Kootenai River drainage, Montana

The reported decline in the abundance, distribution, and genetic diversity of Columbia River redband trout Oncorhynchus mykiss gairdneri (a rainbow trout subspecies) has prompted fisheries managers to investigate their habitat requirements, identify critical habitat, and develop effective conservation and recovery programs. We analyzed the microhabitat, mesohabitat, and macrohabitat use and distribution of Columbia River redband trout by means of snorkel surveys in two watersheds in the Kootenai River drainage, Montana and Idaho, during the summers of 1997 and 1998. Juvenile (36–125 mm total length, TL) and adult (>=126 mm TL) fish preferred deep microhabitats (>=0.4 m) with low to moderate velocities (<=0.5 m/s) adjacent to the thalweg. Conversely, age-0 (<=35 mm) fish selected slow water (<=0.1 m/s) and shallow depths (<=0.2 m) located in lateral areas of the channel. Age-0, juvenile, and adult fish strongly selected pool mesohabitats and avoided riffles; juveniles and adults generally used runs in proportion to their availability. At the macrohabitat scale, density of Columbia River redband trout (35 mm) was positively related to the abundance of pools and negatively related to stream gradient. The pool: riffle ratio, gradient, and stream size combined accounted for 80% of the variation in density among 23 stream reaches in five streams. Our results demonstrate that low-gradient, medium-elevation reaches with an abundance of complex pools are critical areas for the production of Columbia River redband trout. These data will be useful in assessing the impacts of land-use practices on the remaining populations and may assist with habitat restoration or enhancement efforts.

Montana↗

USGS2004

Immunomodulation and disease resistance in postyearling rainbow trout infected with Myxobolus cerebralis, the causative agent of whirling disease

Myxobolus cerebralis , the myxosporean parasite that causes whirling disease, has a number of deleterious effects on its salmonid host. Although it is well established that juvenile salmonids in the active stages of whirling disease mount an immune response to the pathogen, the occurrence and longevity of any related immunomodulatory effects are unknown. In this study, postyearling rainbow trout Oncorhynchus mykiss infected with M. cerebralis were examined for leukocyte functions and for resistance to Yersinia ruckeri , a bacterial pathogen of salmonids. Compared with uninfected controls, M. cerebralis -infected fish showed lower proliferative lymphocyte responses to four mitogens (concanavalin A, pokeweed mitogen, phytohemagglutinin, and lipopolysaccharide). Conversely, M. cerebralis -infected fish displayed greater bactericidal activity of anterior kidney macrophages than did uninfected fish. After bath challenges with Y. ruckeri , M. cerebralis -infected fish had slightly lower survival and a more rapid onset of mortality than did the control fish. Renal tissue and fecal samples from M. cerebralis -infected and uninfected survivors were cultured for the presence of Y. ruckeri , and no difference in prevalence was noted between the two groups. Because immunomodulatory changes in the M. cerebralis -infected fish involved functional enhancement and suppression of different leukocyte populations, disease resistance among M. cerebralis -infected fish in the later stages of whirling disease will probably vary with the secondary pathogen and the nature of immune response the pathogen evokes.

Journal of Aquatic Animal Health↗

USGS2005

Laboratory studies on the vulnerability of young white sturgeon to predation

Despite evidence of annual spawning by white sturgeon Acipenser transmontanus in rivers of the northwestern United States and Canada, in some years and locations little or no recruitment of age-0 white sturgeon has been observed. We examined the vulnerability of white sturgeon larvae and juveniles to predation to further understand possible causes of mortality. We were particularly interested in the vulnerability of older larvae and juveniles because at about 25 mm total length (TL) white sturgeon develop sharp dorsal and lateral scutes that may act as a morphological defense. In the laboratory, white sturgeon ranging from newly hatched larvae to about 170-mm TL juveniles were exposed to predatory fishes they might encounter in the natural environment. We found that channel catfish Ictalurus punctatus (mean TL = 464 mm) and northern pikeminnow Ptychocheilus oregonensis (mean TL = 472 mm) ate white sturgeon up to mean sizes of 121 and 134 mm TL, respectively. Conversely, similarly sized walleyes Sander vitreus ingested almost no white sturgeon, although juvenile walleyes (mean TL = 184 mm) ate white sturgeon up to 59 mm TL. The smallest predator we tested, prickly sculpins Cottus asper (mean TL = 126 mm), ate white sturgeon up to a mean TL of 50 mm. Our study demonstrated that predation is a likely cause of mortality of age-0 white sturgeon and may be contributing to the year-class failures that have been observed. In addition, the results from this study could be used to reduce the predation risk of artificially propagated white sturgeon released to augment declining populations since fish could be reared to sizes where their vulnerability is low.

North American Journal of Fisheries Management↗

USGS2010

The bioenergetic consequences of invasive-induced food web disruption to Lake Ontario alewives

Alewives Alosa pseudoharengus are the dominant prey fish in Lake Ontario, and their response to ecological change can alter the structure and function of the Lake Ontario food web. Using stochastic population-based bioenergetic models of Lake Ontario alewives for 1987–1991 and 2001–2005, we evaluated changes to alewife production, consumption, and associated bioenergetic ratios after invasive-induced food web disruption. After the disruption, mean biomass of alewives declined from 28.0 to 14.6 g/m 2 , production declined from 40.8 to 13.6 g·m −2 ·year −1 , and consumption declined from 342.1 to 137.2 g·m −2 ·year −1 , but bootstrapping of error sources suggested that the changes were not statistically significant. Population-based bioenergetic ratios of production to biomass ( P/B ratio), total consumption to biomass ( Q/B ratio), and production efficiency did not change. Pathways of energy flow measured as prey-group-specific Q/B ratios changed significantly between the two time periods for invasive predatory cladocerans (from 0.6 to 1.3), Mysis diluviana (from 0.4 to 2.5), and other prey (from 0.8 to 0.1), but the observed decline in the zooplankton Q/B ratio (from 10.6 to 5.5) was not significant. Gross production efficiency did not change; values ranged from 8% to 15%. Age-group mean gross conversion efficiency (GCE) declined with age; GCE ranged from 7.5% to 11.0% for yearlings, was approximately 5% for age-2 alewives, and was less than 2% for age-3 and older alewives. The GCE increased significantly between the time periods for yearling alewives. Our analyses support the hypothesis that after 2003, alewives could not sustain their growth while feeding on zooplankton closer to shore. Modeling of observed spatial variation in diet and alternative occupied temperatures demonstrates the potential for reducing consumption by alewives. Our results suggest that Lake Ontario alewives can exploit spatial heterogeneity in resource patches and thermal habitat to partially mitigate the effects of food web disruption. Fish management implications are discussed.

North American Journal of Fisheries Management↗

USGS2020

Looking at the bigger picture: How abundance of nesting and brooding habitat influences lek-site selection by Lesser Prairie-Chickens

Lesser Prairie-Chicken ( Tympanuchus pallidicinctus ) populations have declined throughout most of their distribution since the mid-1980s. These declines are largely attributed to loss of habitat through the conversion and expansion of cropland, construction of oil wells and other anthropogenic features on the landscape, and grazing intensification. Changes in habitat availability and quality are seemingly having a disproportionate effect on the reproductive habitat of Lesser Prairie-Chickens, as some populations continue to decline. Nest and brood survival are crucial to population growth of Lesser Prairie-Chickens, with adequate reproductive habitat vital to population persistence. To better understand the influence of reproductive habitat availability on populations, we quantified the composition of reproductive habitat in lek landscapes across the northern extent of the Lesser Prairie-Chicken range. We measured vegetation at six study sites in Kansas and Colorado from 2013–2016. We sought to quantify available nest and brooding habitat adjacent to leks, investigate the relationship between reproductive habitat availability and lek attendance by males at several spatial scales, and examine vegetation characteristics that influence lek attendance. Within 5 km of a lek, 25% (2546/10,320 points) and 26% (2682/10,320 points) of random locations provided nesting and brooding habitat, respectively. Changes to reproductive habitat at both scales affected male attendance at leks. Visual obstruction of vegetation was the main predictor of male lek attendance at both spatial scales and limited the amount of reproductive habitat in lek landscapes. Accordingly, management should increase visual obstruction throughout the Lesser Prairie-Chicken range to increase reproductive success and improve populations to facilitate achieving the conservation goal set by the Western Association of Fish and Wildlife Agencies of a 10 y average Lesser Prairie-Chicken population of 67,000 birds.

Colorado, Kansas↗

USGS2002

Does increasing daylength control seasonal changes in clutch sizes of Northern Pintails ( Anas acuta )?

We evaluated spatiotemporal variation in clutch sizes of Northern Pintails (pintails; Anas acuta ) nesting in California (1985 to 1996), North Dakota (1982 to 1985), Saskatchewan (1982 to 1985) and Alaska (1991 to 1993) to determine whether seasonal declines in clutch size varied in ways that were consistent with a controlling influence of increasing day length. Pintails began nesting in mid-March in California, mid-April in North Dakota and Saskatchewan, and mid-May in Alaska. Observed durations of nesting were 70 ± 2.6 days (SE) in California, 60 ± 6.3 days in North Dakota, 66 ± 1.3 days in Saskatchewan, and 42 ± 0.7 days in Alaska. Annual differences were the principal source of variation in mean clutch sizes (σ̂ Y 2 = 0.15, SE = 0.049), which varied little among study locations (σ̂ A 2 = 0.002, SE = 0.013). Predicted rates of seasonal decline in clutch sizes increased with latitude early in the nesting season, but declined as the nesting season progressed, except in California. Rates of decline in clutch sizes thus were not directly related to rates of increase in day length. Predicted declines in numbers of eggs per clutch over the nesting season were similar for all four locations (range, 3.05–3.12) despite wide variation in durations of nesting. Evidence suggests that reduced nutrient availability during nesting contributes to a higher rate of decline in clutch sizes in Alaska than in temperate regions. Pintails that nest early lay large initial clutches, but thereafter clutch sizes decline rapidly and breeding terminates early. This reproductive strategy is adaptive because young that hatch earliest exhibit the highest survival rates; however, the conversion of grassland to cropland on the primary prairie breeding grounds has reduced hatching rates of clutches laid early in the nesting season. Under these conditions, the limited capacity to renest in late spring on their prairie breeding grounds probably has contributed to Pintail population declines.

The Auk↗

USGS2018

Diel fledging patterns among grassland passerines: Relative impacts of energetics and predation risk

The time of day that nestlings fledge from a nest is thought to be shaped by predation risk and energetics. To minimize predation risk, fledging is predicted to start as early in the day as possible so that nestlings can maximize time outside the nest to find a safe place to stay before nightfall. Fledging times are predicted to be tightly grouped and to not be affected by the number of nestlings, given that all nestlings are responding to the same relative risk of predation. Conversely, energetic considerations predict that fledging time of day should vary so that nestlings can maximize energy intake before having to forage for themselves. However, data to evaluate the relative importance of these drivers in grassland birds are scarce because of the difficulty of observing nestlings as they fledge. We used nest surveillance video from 178 nests to evaluate how the initiation and duration of fledging varied among 7 grassland passerine species, as well as by the number of nestlings in the nest and fledging date. Fledging initiation varied most strongly by species, with some effects of date. Across species, the median start time of fledging was 4.55 hr after sunrise. Fledging before the solstice started ∼30 min earlier compared to fledging at or after the solstice. Fledging duration increased with number of nestlings in the nest and was spread over >1 day in 21% of nests. While our results primarily supported the hypothesis that fledging is motivated by energetic considerations, additional data on basic life history traits and behavior will be needed to fully understand how fledging grassland birds balance energetics against predation risk.

The Auk↗

USGS2012

Mapping anuran habitat suitability to estimate effects of grassland and wetland conservation programs

The conversion of the Northern Great Plains of North America to a landscape favoring agricultural commodity production has negatively impacted wildlife habitats. To offset impacts, conservation programs have been implemented by the U.S. Department of Agriculture and other agencies to restore grassland and wetland habitat components. To evaluate effects of these efforts on anuran habitats, we used call survey data and environmental data in ecological niche factor analyses implemented through the program Biomapper to quantify habitat suitability for five anuran species within a 196 km 2 study area. Our amphibian call surveys identified Northern Leopard Frogs ( Lithobates pipiens ), Wood Frogs ( Lithobates sylvaticus ), Boreal Chorus Frogs ( Pseudacris maculata ), Great Plains Toads ( Anaxyrus cognatus ), and Woodhouse’s Toads ( Anaxyrus woodhousii ) occurring within the study area. Habitat suitability maps developed for each species revealed differing patterns of suitable habitat among species. The most significant findings of our mapping effort were 1) the influence of deep-water overwintering wetlands on suitable habitat for all species encountered except the Boreal Chorus Frog; 2) the lack of overlap between areas of core habitat for both the Northern Leopard Frog and Wood Frog compared to the core habitat for both toad species; and 3) the importance of conservation programs in providing grassland components of Northern Leopard Frog and Wood Frog habitat. The differences in habitats suitable for the five species we studied in the Northern Great Plains, i.e., their ecological niches, highlight the importance of utilizing an ecosystem based approach that considers the varying needs of multiple species in the development of amphibian conservation and management plans.

Copeia↗

USGS2024

Thermal traits of anurans database for the southeastern United States (TRAD): A database of thermal trait values for 40 anuran species

Thermal traits, or how an animal responds to changing temperatures, impacts species persistence and thus biodiversity. Trait databases, as repositories of consolidated, measured organismal attributes, allow researchers to link study species with specific trait values, enabling comparisons within and among species. Trait databases also help lay the groundwork to build mechanistic linkages between organisms and the environment. However, missing or hidden physiological trait data preclude building mechanistic estimates of climate change vulnerability for many species. Thus, physiologically focused trait databases present an opportunity to consolidate data and enable species-specific or multispecies, mechanistic evaluations of climate change vulnerability. Here, we present TRAD: thermal traits of anurans database for the southeastern United States, a database of thermal trait values related to physiological thermoregulation (critical thermal minima and maxima, preferred temperature), behavioral thermoregulation (activity period, retreat emergence temperature, basking temperature, minimum and maximum foraging temperatures), and body mass for 37 anuran species found within the southeastern United States. In total, TRAD contains 858 reported trait values for 37 of 40 species found in the region from 267 peer-reviewed papers, dissertations, or theses and is easily linked with trait data available in ATraiU, an ecological trait database for anurans in the United States. TRAD contains trait values for multiple life stages and a summarization of interspecific adult trait values. Availability of trait data varied widely among traits and species. Estimates of mass were the most common trait values reported, with values available for 32 species. Behavioral trait values comprised 23% of our database, with activity period available for 34 species. We found the most trait values for Cope's Gray Treefrog ( Dryophytes chrysoscelis ), with at least one trait value for eight traits in the database. Conversely, species in the genus Pseudacris generally had the fewest trait values available. Species with the largest geographic range sizes also had the greatest coverage of data across traits (rho 5 0.75, P , 0.001). TRAD can aid studies of anuran response to changing temperatures, physiological niche space and limitations, and potential drivers of anuran geographic range limits, influencing our understanding of other ecological and evolutionary patterns and processes and enabling multispecies comparisons of potential risk and resilience in the face of climate change.

southeastern United States↗

USGS2005

Comparative susceptibility of introduced forest-dwelling mosquitoes in Hawai'i to avian malaria, Plasmodium relictum

To identify potential vectors of avian malaria in Hawaiian native forests, the innate susceptibility of Aedes albopictus, Wyeomyia mitchellii, and Culex quinquefasciatus from 3 geographical sites along an altitudinal gradient was evaluated using local isolates of Plasmodium relictum. Mosquitoes were dissected 5-8 and 9-13 days postinfective blood meal and microscopically examined for oocysts and salivary-gland sporozoites. Sporogony was completed in all 3 species, but prevalence between species varied significantly. Oocysts were detected in 1-2% and sporozoites in 1-7% of Aedes albopictus that fed on infected ducklings. Wyeomyia mitchellii was slightly more susceptible, with 7-19% and 7% infected with oocysts and sporozoites, respectively. In both species, the median oocyst number was 5 or below. This is only the second Wyeomyia species reported to support development of a malarial parasite. Conversely, Culex quinquefasciatus from all 3 sites proved very susceptible. Prevalence of oocysts and sporozoites consistently exceeded 70%, regardless of gametocytemia or origin of the P. relictum isolate. In trials for which a maximum 200 oocysts were recorded, the median number of oocysts ranged from 144 to 200. It was concluded that Culex quinquefasciatus is the primary vector of avian malaria in Hawai'i. ?? American Society of Parasitologists 2005.

Journal of Parasitology↗

USGS2015

Breeding habitat associations and predicted distribution of an obligate tundra-breeding bird, Smith's Longspur

Smith's Longspur ( Calcarius pictus ) is a species of conservation concern which breeds in Arctic habitats that are expected to be especially vulnerable to climate change. We used bird presence and habitat data from point-transect surveys conducted at 12 sites across the Brooks Range, Alaska, 2003–2009, to identify breeding areas, describe local habitat associations, and identify suitable habitat using a predictive model of Smith's Longspur distribution. Smith's Longspurs were observed at seven sites, where they were associated with a variety of sedge–shrub habitats composed primarily of mosses, sedges, tussocks, and dwarf shrubs; erect shrubs were common but sparse. Nonmetric multidimensional scaling ordination of ground cover revealed positive associations of Smith's Longspur presence with sedges and mosses and a negative association with high cover of shrubs. To model predicted distribution, we used boosted regression trees to relate landscape variables to occurrence. Our model predicted that Smith's Longspurs may occur in valleys and foothills of the northeastern and southeastern mountains and in upland plateaus of the western mountains, and farther west than currently documented, over a predicted area no larger than 15% of the Brooks Range. With climate change, shrubs are expected to grow larger and denser, while soil moisture and moss cover are predicted to decrease. These changes may reduce Smith's Longspur habitat quality and limit distribution in the Brooks Range to poorly drained lowlands and alpine plateaus where sedge–shrub tundra is likely to persist. Conversely, northward advance of shrubs into sedge tundra may create suitable habitat, thus supporting a northward longspur distribution shift.

The Condor↗

USGS2018

Reproductive response of Arizona Grasshopper Sparrows to weather patterns and habitat structure

Avian species endemic to desert grasslands of North America contend with significant ecological challenges, including monsoonal rains, droughts, and variable temperatures. These birds have evolved physiological and behavioral means of coping with such extremes, but ongoing changes to temperature and precipitation patterns are affecting their breeding phenology, reproductive success, and population growth rates. We examined how seasonal and daily weather conditions and habitat structure were associated with the nest survival of Arizona Grasshopper Sparrows ( Ammodramus savannarum ammolegus ) in the semidesert and plains grasslands of southeastern Arizona, USA. The mean ± SE daily survival rate (DSR) of nests was 0.960 ± 0.006, corresponding to overall nest success of 46%. The previous season's precipitation, large rain events, and nest concealment were the most important factors explaining DSR. Grasshopper Sparrow nest survival decreased with a wetter previous growing season and with large rain events on previous days. Nests that were more concealed had lower survival rates. There was some evidence that nest survival was lower later in the nesting season. In addition, when nest concealment was included in models, there were positive but weak associations between other vegetation variables and DSR—nests with higher visual obstruction at the nest and nest plot scales, and nests that were farther from shrubs >2 m tall, showed higher survival rates. Predation was the major cause of nest failure, suggesting complex interactions among predation, precipitation, and nest concealment. Further, our findings suggest tradeoffs in the potential effects of future climate change on A. s. ammolegus . The increased frequency of extreme storm events predicted for the region may result in reduced nest survival of A. s. ammolegus , but, conversely, lower seasonal precipitation prior to nesting may positively influence nest survival.

Arizona↗

USGS2018

Interisland genetic structure of two endangered Hawaiian waterbirds: The Hawaiian Coot and Hawaiian Gallinule

Most of Hawaii's endemic avifauna are species of conservation concern. Some of Hawaii's endangered waterbirds, however, have increased in number as a result of intensive management of wetlands. To inform these conservation efforts, we examined interisland genetic structure and gene flow within 2 Hawaiian endemic waterbirds, the Hawaiian Coot ( Fulica alai ) and the Hawaiian subspecies of the Common Gallinule ( Gallinula galeata sandvicensis ), using microsatellite and mitochondrial loci. Hawaiian Coots and Hawaiian Gallinules occupy coastal wetlands and exhibit similar life history characteristics and generation times, although they may differ in dispersal propensity. Mark–resight data for Hawaiian Coot indicate interisland movements, whereas Hawaiian Gallinules are sedentary. Genetic diversity is partitioned across the landscape differently for Hawaiian Coots and Hawaiian Gallinules; patterns of variation are likely influenced by behavioral and ecological mechanisms. Hawaiian Coots exhibit low levels of structure at microsatellite loci ( F ST = 0.029) and high levels of gene flow among islands. Conversely, Hawaiian Gallinules are highly structured across marker types (microsatellite F ST = 0.205, mtDNA control region F ST = 0.370, mtDNA ND2 F ST = 0.087), with restricted recent gene flow. Patterns of gene flow have changed after the population declines in the early to mid-1900s. Gene flow estimates indicate historical dispersal from Kauai to Oahu in both species, while recent estimates show individual Hawaiian Coots dispersing from Oahu and restricted gene flow between islands for the Hawaiian Gallinule. Changes in gene flow through time suggest that patterns of dispersal may be an artifact of the availability of habitat, which may be indirectly associated with the synergistic influences of population density and wetland quality. Despite recent population size increases for both species, continued threats to Hawaiian waterbirds (i.e. nonnative mammalian predators and invasive plants, avian disease, altered hydrology, and saltwater inundation of freshwater wetlands) will likely require continued active management to maintain viable populations.

Hawaii↗

USGS2020

Giant Gartersnakes (Thamnophis gigas) exploit abundant non-native prey while maintaining their appetite for native anurans

The introductions of nonnative species can cause great change in the trophic dynamics of native species. Giant Gartersnakes, endemic predators in the Central Valley of California, are listed as threatened because of the conversion of their once vast wetland habitat to agriculture. Further contributing to this snake's changing ecology is the introduction of many nonnative prey species, resulting in a diet that is almost completely composed of nonnative species. In order to determine whether these snakes actively select their prey or simply consume what is abundant, we examined prey selection by adult Giant Gartersnakes in the context of what prey was available to each individual. Giant Gartersnakes selected a native anuran over nonnative anuran and fish species despite these nonnatives dominating the available species composition. These results contribute to understanding the mechanisms underlying Giant Gartersnake diets in the contemporary landscape and can lead to improved management of prey communities for Giant Gartersnakes and other native predators.

Herpetologica↗

USGS2006

Fens and floodplains of the temperate zone: Present status, threats, conservation and restoration

This Special Feature focuses on lowland fens and flood plains. In this introduction we discuss the most important mire-related terms, present status, threats and conservation and restoration attempts. Floodplains and especially lowland fens are rare and vulnerable ecosystems. They are highly threatened all over the world because of direct conversion to agricultural land and especially the lack of appropriate management and altered catchment hydrology. Finally we present a framework for the conservation and restoration of these ecosystems. This consists of (1) optimising abiotic conditions; (2) safeguarding propagule availability of the target species; (3) creating and maintaining conditions for (re)establishment of these species, and (4) appropriate management to keep the conditions suitable. ?? IAVS; Opulus Press.

Conference Paper↗

USGS2015

Deep-sea ostracods from the South Atlantic sector of the Southern ocean during the Last 370,000 years

We report changes of deep-sea ostracod fauna during the last 370,000 yr from the Ocean Drilling Program (ODP) Hole 704A in the South Atlantic sector of the Southern Ocean. The results show that faunal changes are coincident with glacial/interglacial-scale deep-water circulation changes, even though our dataset is relatively small and the waters are barren of ostracods until mid-MIS (Marine Isotope Stage) 5. Krithe and Poseidonamicus were dominant during the Holocene interglacial period and the latter part of MIS 5, when this site was under the influence of North Atlantic Deep Water (NADW). Conversely, Henryhowella and Legitimocythere were dominant during glacial periods, when this site was in the path of Circumpolar Deep Water (CPDW). Three new species (Aversovalva brandaoae, Poseidonamicus hisayoae, and Krithe mazziniae) are described herein. This is the first report of Quaternary glacial/interglacial scale deep-sea ostracod faunal changes in the Southern and South Atlantic Oceans, a key region for understanding Quaternary climate and deep-water circulation, although the paucity of Quaternary ostracods in this region necessitates further research. ?? 2009 The Paleontological Society.

Journal of Paleontology↗

USGS2002

How sedge meadow soils, microtopography, and vegetation respond to sedimentation

The expansion of urban and agricultural activities in watersheds of the Midwestern USA facilitates the conversion of species-rich sedge meadows to stands of Phalaris arundinacea and Typha spp. We document the role of sediment accumulation in this process based on field surveys of three sedge meadows dominated by Carex stricta , their adjacent Phalaris or Typha stands, and transitions from Carex to these invasive species. The complex microtopography of Carex tussocks facilitates the occurrence of other native species. Tussock surface area and species richness were positively correlated in two marshes (r 2 =0.57 and 0.41); on average, a 33-cm-tall tussock supported 7.6 species. Phalaris also grew in tussock form in wetter areas but did not support native species. We found an average of 10.5 Carex tussocks per 10-m transect, but only 3.5 Phalaris tussocks. Microtopographic relief, determined with a high-precision GPS, measured 11% greater in Carex meadows than Phalaris stands. Inflowing sediments reduced microtopographic variation and surface area for native species. We calculated a loss of one species per 1000 cm 2 of lost tussock surface area, and loss of 1.2 species for every 10-cm addition of sediment over the sedge meadow surface. Alluvium overlying the sedge meadow soil had a smaller proportion of organic matter content and higher dry bulk density than the buried histic materials. We conclude that sedimentation contributes to the loss of native species in remnant wetlands.

Wetlands↗