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At least 217 records · Page 12Linked to original sources

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, 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↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Susquehanna River and Yellow Breeches Creek at Steelton, Highspire, and New Cumberland, 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↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, Susquehanna River at Lemoyne, 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↗

USGS1972

Map showing flood of June 1972 resulting from tropical storm Agnes, West Branch Susquehanna River and Bald Eagle Creek at Lock Haven, 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↗

USGS1996

Summary of data-collection activities and effects of flooding from tropical storm Alberto in parts of Georgia, Alabama, and Florida, July 1994

Parts of central and southwestern Georgia, southeastern Alabama, and the western panhandle of Florida were devastated by floods resulting from rainfall produced by Tropical Storm Alberto in July 1994. As tributary floodwaters combined and moved downstream in the Flint, Ocmulgee, and Choctawhatchee Rivers, peak discharges exceeded the 100-year flood discharges along most stream reaches. Along the Flint River, the 100-year flood stage was exceeded at Montezuma by 3.7 ft; at Albany, by 5.1 ft; at Newton, by 3.9 ft; and at Bainbridge by 2.2 ft. Along the Ocmulgee River, the 100-year flood was exceeded at Juliette, by 5.4 ft; at Macon, by 2.2 ft; and at Hawkinsville by 3.9 ft. Peak discharges exceeded the 100-year flood discharges along the Choctawhatchee River from Newton, Ala., to Bruce, Fla. Discharge measurements were made at many gaging stations throughout the area of flooding. Streamflow velocities are obtained during the process of making the discharge measurement. Velocity data are given for selected gaging stations on two streams in Georgia. Scour around pier and abutment foundations caused settling or washout at most bridge failures. Scour mechanisms at these bridges include local scour, contraction scour, and scour plus bank instability of the general stream reach where the bridge is located. Eighteen feet of predominantly contraction scour was measured during the flood at the U.S. Highway 82 crossing of Flint River at Albany, Ga.

Alabama, Florida, Georgia↗