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USGS2013

Spatial extent and dynamics of dam impacts on tropical island freshwater fish assemblages

Habitat connectivity is vital to the persistence of migratory fishes. Native tropical island stream fish assemblages composed of diadromous species require intact corridors between ocean and riverine habitats. High dams block fish migration, but low-head artificial barriers are more widespread and are rarely assessed for impacts. Among all 46 drainages in Puerto Rico, we identified and surveyed 335 artificial barriers that hinder fish migration to 74.5% of the upstream habitat. We also surveyed occupancy of native diadromous fishes (Anguillidae, Eleotridae, Gobiidae, and Mugilidae) in 118 river reaches. Occupancy models demonstrated that barriers 2 meters (m) high restricted nongoby fish migration and extirpated those fish upstream of 4-m barriers. Gobies are adapted to climbing and are restricted by 12-m barriers and extirpated upstream of 32-m barriers. Our findings quantitatively illustrate the extensive impact of low-head structures on island stream fauna and provide guidance for natural resource management, habitat restoration, and water development strategies.

BioScience↗

USGS2014

A new species of freshwater eel-tailed catfish of the genus Tandanus ( Teleostei: Plotosidae ) from the Wet Tropics Region of Eastern Australia

Tandanus tropicanus , new species, is described based on specimens from streams in the wet tropics region of northeast Queensland. Previously, two species were recognized in the genus Tandanus : T. tandanus of eastern Australia and T. bostocki of Western Australia. A combination of meristic and morphometric characters distinguishes the new species from all congeners. Further, taxonomic distinctness based on morphologic differences between the new species and all congeners is corroborated by genetic analyses.

Queensland↗

USGS2007

Reproductive biology of the violet-chested hummingbird in Venezuela and comparisons with other tropical and temperate hummingbirds

We provide details on the breeding biology of the Violet-chested Hummingbird (Sternoclyta cyanopectus) based on 67 nests studied in Yacambu?? National Park, Venezuela, from 2002 through 2006. Clutch size was two white eggs, usually laid every other day. Fresh egg mass (0.95 ?? 0.14 g) was 15% of female mass. Incubation and nestling periods were 20.4 ?? 0.3 and 26.0 ?? 0.4 days, respectively. Nest attentiveness increased from 60% in early incubation to 68% in late incubation. The female spent 50% of her time brooding young nestlings, but ceased brooding by 13 days of age. Only the female fed the young, with a low rate of nest visitation (3.3 trips per hour) that did not increase with age of the young. Growth rate based on nestling mass (K = 0.28) was slow. Daily predation rates decreased across stages and were 0.064 ?? 0.044, 0.033 ?? 0.008, and 0.020 ?? 0.006 during the egg-laying, incubation, and nestling periods, respectively. Most, but not all, life history traits of the Violet-chested Hummingbird were similar to those reported for other tropical and temperate hummingbirds, providing further evidence that this family shows a relatively narrow range of life history variation. ?? The Cooper Ornithological Society 2007.

Condor↗

USGS2015

Tropical insular fish assemblages are resilient to flood disturbance

Periods of stable environmental conditions, favoring development of ecological communities regulated by density-dependent processes, are interrupted by random periods of disturbance that may restructure communities. Disturbance may affect populations via habitat alteration, mortality, or displacement. We quantified fish habitat conditions, density, and movement before and after a major flood disturbance in a Caribbean island tropical river using habitat surveys, fish sampling and population estimates, radio telemetry, and passively monitored PIT tags. Native stream fish populations showed evidence of acute mortality and downstream displacement of surviving fish. All fish species were reduced in number at most life stages after the disturbance, but populations responded with recruitment and migration into vacated upstream habitats. Changes in density were uneven among size classes for most species, indicating altered size structures. Rapid recovery processes at the population level appeared to dampen effects at the assemblage level, as fish assemblage parameters (species richness and diversity) were unchanged by the flooding. The native fish assemblage appeared resilient to flood disturbance, rapidly compensating for mortality and displacement with increased recruitment and recolonization of upstream habitats.

Ecosphere↗

USGS2007

An evaluation of the mobility of pathogen indicators, Escherichia coli and bacteriophage MS-2, in a highly weathered tropical soil under unsaturated conditions

Laboratory column experiments were conducted to study the effects of anionic polyacrylamide (PAM) polymer and surfactant linear alkylbenzene sulfonate (LAS) on the movement of Escherichia coli and the FRNA phage MS-2. The study was designed to evaluate if PAM or PAM + LAS would enhance the mobility of human pathogens in tropical soils under unsaturated conditions. No breakthrough of phage was observed in a 10 cm column after passing 100 pore volumes of solution containing 1 ?? 108 plaque-forming units (PFU)/ml. In later experiments, after passing 10-20 pore volumes of influent containing 1 ?? 108/ml MS-2 or E. coli through 15 cm columns, the soil was sliced and the organisms eluted. Phage moved slightly deeper in the polymer-treated column than in the control column. There was no measurable difference in the movement of E. coli in either polymer-treated or control columns. The properties of the soil (high amounts of metal oxides, kaolinitic clay), unsaturated flow conditions, and relatively high ionic strengths of the leaching solution attributed to significant retention of these indicators. The impacts of PAM and LAS on the mobility of E. coli or MS-2 phage in the chosen soils were not significant. ?? IWA Publishing 2008.

Journal of Water and Health↗

USGS1976

The abundance and diversity of the herpetofaunas of tropical forest litters

Quantitative and qualitative samples of amphibian and lizard faunas were taken from forest litter in Costa Rica and compared with similar samples collected in Borneo, the Philippines, and Panama. Animal abundance is about ten times greater in Costa Rican lowland wet forest than in Borneo. Radically different routes and rates of energy flow are postulated to account for the difference. In a series of upland (1010-1425 m) samples in the Philippines, the number of litter lizards and frogs increases with elevation. A single upland (1200 m) Costa Rican sample contains about three times as many animals per 100 m2 as two lowland sites. This increase with altitude correlates well with hypotheses that overall tropical forest productivity is greatest at intermediate elevations. Herpetofaunal densities are greater in wet areas compared to dry sites and flat terrain compared to slopes. These observations are linked to the greater variation and lesser total litter fall in dry sites and/or slopes. The number of species of amphibians and lizards regularly inhabiting the litter is similar in all wet lowland forests studied. Increasing elevation and decreasing rainfall correlate with faunas having fewer species. The former is seen as the result of the differential ability of lowland species to invade uplands, and the latter as a decrease in the kind and duration of frog-spawning sites. Reduced equitability with increasing elevation is principally due to the much greater proportional increase of the commonest species. In the evolution of American and Bornean-Philippine wet lowland faunas, frogs with direct development (Eleutherodactylus) have radiated in the former in the same fashion that skinks have in the latter.

Biotropica↗

USGS1993

Rainfall-threshold conditions for landslides in a humid-tropical system

Landslides are triggered by factors such as heavy rainfall, seismic activity, and construction on hillslopes. The leading cause of landslides in Puerto Rico is intense and/or prolonged rainfall. A rainfall threshold for rainfall-triggered landsliding is delimited by 256 storms that occurred between 1959 and 1991 in the central mountains of Puerto Rico, where mean annual rainfall is close to or in excess of 2,000 mm. Forty one of the 256 storms produced intense and/or prolonged rainfall that resulted in tens to hundreds of landslides. A threshold fitted to the lower boundary of the field defined by landslide-triggering storms is expressed as I = 91.46 D -0.82 where I is rainfall intensity in millimeters per hour, and D is duration in hours. Landslide-producing storms occurred at an average rate of 1.2 per year. In general the landslides triggered by short-duration, high-intensity rainfall events were mainly shallow soil slips and debris flows, while the long-duration, low-intensity rainfall produced larger, deeper debris avalanches and slumps. For storms that had durations of up to 10 h, landsliding did not occur until rainfall intensity was as much as three times as high as the rainfall intensity reported as sufficient to trigger landsliding in temperate regions. As storm durations approach 100 h, the rainfall conditions necessary to initiate landsliding in Puerto Rico converge with those defined for temperate regions. A comparison of the Puerto Rico threshold with rainfall data from other humid-tropical regions suggests that the threshold developed for Puerto Rico may be applicable to other similar environments throughout the world.

Geografiska Annaler, Series A: Physical Geography↗

USGS1985

Tropical Pacific silicoflagellate zonation and paleotemperature trends of the late Cenozoic

Quantitative study of late Cenozoic silicoflagellates at tropical Pacific DSDP Sites 572 and 575 shows that the greatest amplitude of fluctuation in relative paleotemperature values occurred in the late Miocene. The coolest minimum paleotemperature values (near 75 = 30) also occurred in the late Miocene. The warmest intervals (Ts = 80 to 100) occurred in the middle Miocene and late Pliocene to Quaternary. In detail, the silicoflagellate relative paleotemperature curve correlates fairly well with the eustatic sea-level curve and deep-sea hiatus sequence. The only upper Cenozoic low-latitude biostratigraphic units not identified are the Distephanus speculum haliomma Subzone and Naviculopsis quadrata Zone, owing to the absence of the nominative species, which probably had nontropical ecologic preference. Several Naviculopsis occurrence events within the Naviculopsis ponticula Zone correlate between DSDP Hole 575A and DSDP Hole 495 off Guatemala. Many local and regional biostratigraphic events are recognized. New taxa identified from DSDP Leg 85 include Dictyocha nola Bukry, n. sp., Distephanus stradneri var. grandis Bukry, n. var., Mesocena elliptica var. rhomboidea Bukry, n. van, and Naviculopsis obtusarca var. acicula Bukry, n. var.

Initial Reports of the D.S.D.P.↗

USGS2012

Connectivity of tropical marine ecosystems--An overview of interdisciplinary research to understand biodiversity and trophic relationships in the Virgin Islands and Puerto Rico

The Virgin Islands and Puerto Rico contain marine reserves and protected areas that encompass a variety of tropical ecosystems, including coral reefs, mangroves, and seagrass beds. Reserves and protected areas are established for a variety of reasons, such as preserving nursery habitats and biodiversity, or reducing anthropogenic effects associated with pollution and land use. Questions remain regarding the effectiveness of these designated areas in preserving and protecting spatially connected habitats and associated fishes and invertebrates. Scientists from the U.S. Geological Survey (USGS), University of Florida, and Arkansas State University are collaborating on interdisciplinary research in the Virgin Islands and Puerto Rico to examine the biodiversity and trophic dynamics of fishes and invertebrates residing in connected mangroves, seagrasses, and coral reefs to discern the effectiveness of current marine reserves and protected areas for conserving reef resources.

Fact Sheet↗

USGS2007

Sea ice concentration temporal variability over the Weddell Sea and its relationship with tropical sea surface temperature

Principal Components Analysis (PCA) in S-Mode (correlation between temporal series) was performed on sea ice monthly anomalies, in order to investigate which are the main temporal patterns, where are the homogenous areas located and how are they related to the sea surface temperature (SST). This analysis provides 9 patterns (4 in the Amundsen and Bellingshausen Seas and 5 in the Weddell Sea) that represent the most important temporal features that dominated sea ice concentration anomalies (SICA) variability in the Weddell, Amundsen and Bellingshausen Seas over the 1979-2000 period. Monthly Polar Gridded Sea Ice Concentrations data set derived from satellite information generated by NASA Team algorithm and acquired from the National Snow and Ice Data Center (NSIDC) were used. Monthly means SST are provided by the National Center for Environmental Prediction reanalysis. The first temporal pattern series obtained by PCA has its homogeneous area located at the external region of the Weddell and Bellingshausen Seas and Drake Passage, mostly north of 60°S. The second region is centered in 30°W and located at the southeast of the Weddell. The third area is localized east of 30°W and north of 60°S. South of the first area, the fourth PC series has its homogenous region, between 30° and 60°W. The last area is centered at 0° W and south of 60°S. Correlation charts between the five Principal Components series and SST were performed. Positive correlations over the Tropical Pacific Ocean were found for the five PCs when SST series preceded SICA PC series. The sign of the correlation could relate the occurrence of an El Niño/Southern Oscillation (ENSO) warm (cold) event with posterior positive (negative) anomalies of sea ice concentration over the Weddell Sea.

Open-File Report↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Genesee River at Avon, New York

In June 1972, tropical storm Agnes caused severe flooding in Pennsylvania and southern New York. The floods on many major streams were the highest known since the river valleys were settled. Maximum discharges were as much as twice the discharge of a 50-year flood. In southern New York, large areas in Corning, Elmira, Wellsville, Salamanca, and in many smaller communities were inundated to depths of sever a feet. Levels of all of the Finger Lakes were higher than any previously recorded, and extensive flooding of lakeside properties resulted. The extent of flooding shown on the map was delineated by the U.S. Geological Survey from aerial photography and limited field surveys.

New York↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Canisteo River at Canisteo, New York

In June 1972, tropical storm Agnes caused severe flooding in Pennsylvania and southern New York. The floods on many major streams were the highest known since the river valleys were settled. Maximum discharges were as much as twice the discharge of a 50-year flood. In southern New York, large areas in Corning, Elmira, Wellsville, Salamanca, and in many smaller communities were inundated to depths of several feet. Levels of all of the Finger Lakes were higher than any previously recorded, and extensive flooding of lakeside properties resulted. The extent of flooding shown on the map was delineated by the U.S. Geological Survey from aerial photography and limited field surveys

New York↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Susquehanna River at Kingston, Pennsylvania

In June 1972, tropical storm Agnes caused severe flooding within a broad area extending from North Carolina to Southern New York. Flood elevations along the Susquehanna River were the highest ever recorded. In the Wilkes-Barre area, flood elevations exceeded those of 1865 and 1936 by about eight feet. Maximum discharges were about 40 percent greater than those of a 50-year flood. Property damages from flooding in the Wyoming Valley, in which Wilkes-Barre lies, far exceeded those in any are of similar size affected by the storm. The extent of the flooding on the map was delineated by the U.S. Geological Survey from field surveys made soon after the flood. Sections of levees and railroad grades that were not overtopped are not delineated.

Pennsylvania↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Susquehanna River at Wilkes-Barre and Plymouth, Pennsylvania

Pennsylvania↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Susquehanna River in the vicinity of Wilkes-Barre and Pittston, Pennsylvania

Pennsylvania↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Cayuga Inlet and Cayuga Lake at Ithaca, New York

In June 1972, tropical storm Agnes caused severe flooding in Pennsylvania and southern New York. The floods on many major streams were the highest known since the river valleys were settled. Maximum discharges were as much as twice the discharge of a 50-year flood. In southern New York, large areas in Corning, Elmira, Wellsville, Salamanca, and in many smaller communities were inundated to depths of several feet. Levels of all of the Finger Lakes were higher than any previously recorded, and extensive flooding of lakeside properties resulted. The extent of flooding shown on the map was delineated by the U.S. Geological Survey from field surveys made immediately after the flood.

New York↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Owasco Inlet at Moravia, New York

In June 1972, tropical storm Agnes caused severe flooding in Pennsylvania and southern New York. The floods on many major streams were the highest known since the river valleys were settled. Maximum discharges were as much as twice the discharge of a 50-year flood. In southern New York, large areas in Corning, Elmira, Wellsville, Salamanca, and in many smaller communities were inundated to depths of several feet. Levels of all of the Finger Lakes were higher than any previously recorded, and extensive flooding of lakeside properties resulted. The extent of flooding shown on the map was delineated by the U.S. Geological Survey by field surveys.

New York↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Susquehanna River and Swatara Creek at Middletown, Pennsylvania

In June 1972, tropical storm Agnes caused severe flooding in Pennsylvania and southern New York. The floods on many major streams were the highest known since the river valleys were settled. Maximum discharges were as much as twice the discharge of a 50-year flood. In central Pennsylvania, large areas in Lock Haven, Mill Hall, Wilkes-Barre, Kingston, Pittston, Harrisburg, and in many smaller communities were inundated to depths of several feet. The extent of flooding shown on the map was delineated by the U.S. Geological Survey from field surveys made soon after the flood.

Pennsylvania↗