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At least 559 records · Page 31Linked to original sources
USGS2014

Sex in the Suwannee, the secretive love life of Gulf Sturgeons

Mid-February in the Gulf of Mexico and a timeless ritual is about to repeat itself for perhaps the millionth time. Some mysterious signal, possibly increasing day length, flips an internal switch, feeding stops, and the homeward migration begins for the Gulf Sturgeon ( Acipenser oxyrinchus desotoi ). From far flung places along the Gulf Coast, Gulf Sturgeons start heading back to their natal rivers – they know the way instinctively. Maybe they seek out the special chemical taste of their home river, imprinted at hatching. Or perhaps the ultrasensitive electric organs decorating the underside of the snout can follow the map of the earth’s magnetic field. Either way, time to make a beeline for the welcoming waters of the Suwannee River, or maybe the Apalachicola, Choctawhatchee, or one of four other spawning rivers. Some of the adults are on a special mission – time to spawn, time to perpetuate the species. Mature males form the first wave in this homebound marathon, eager to get to the spawning grounds, eager to be the first to greet ready females with a series of sharp clicking sounds. Only spawning once each three years, females laden with large black eggs demure, taking their time, arriving in mid to late March, a month behind the early males. But most sturgeons, juveniles and immature adults not ready to spawn, are simply heading home. Not prompted by the spawning urge, they are just following the ancient annual cycle of intense winter feeding in the Gulf, followed by several months of fasting and R&R in the river.

Alabama, Florida, Georgia, Louisiana, Mississippi↗
USGS2015

Snake River fall Chinook salmon life history investigations, 1/1/2013 – 12/31/2013

Smallmouth bass predation on subyearling fall Chinook salmon was examined in the upper portion of Lower Granite Reservoir during 2013. During the time subyearlings were present in the reservoir, smallmouth bass were collected, their stomach contents removed for diet analysis, and their abundance estimated with mark-recapture techniques. In 2013, the greatest consumption of subyearlings by smallmouth bass occurred in late May and early June—as much as 50% of their diet by weight. Sand rollers were the most common non-salmonid fish consumed by smallmouth bass. In the section of the reservoir above the confluence with the Clearwater River, the abundance of bass was higher in non-riprap habitat than in riprap, but the opposite was true in the section below the confluence. We estimated that over 168,000 subyearlings were lost to smallmouth bass predation in 2013. Given the predominance of sand rollers in the diet of smallmouth bass, we believe this species reduces predation on subyearling fall Chinook salmon. A complete report of our findings is provided in the Appendix.

Washington↗
USGS2015

Life on the edge in eastern Alaska: Basal Ordovician(Tremadocian), platform-margin faunas of the Jones Ridge Formation

As the most fossiliferous and least deformed succession of unequivocally Laurentian lower Paleozoic strata in Alaska, the Jones Ridge Limestone has provided critical data for numerous stratigraphic studies (e. g. Palmer 1968; Harris et al. 1995; Dumoulin et al. 2002; Dumoulin and Harris 2012) focused on the Cambrian and Ordovician of northwestern North America/northeastern Laurentia (Figure 1). The Jones Ridge faunas are also significant in having provided the type material for some of the widespread and biostratigraphically useful latest Furongian and (perhaps) earliest Tremadocian species described by Kobayashi (1936) and Palmer (1968). Unfortunately, some of those taxa were based on very limited material for which, in the earlier study in particular, no detailed information regarding locality or stratigraphic horizon was provided. The limited amount of information and material available for study from Jones Ridge results largely from its remote location on the Yukon-Alaska boundary approximately 25km north of Eagle, Alaska, which renders it accessible only by helicopter. Parts of three field seasons (2010, 2011, and 2014) were invested in re-description and intensive sampling of the type section of the Jones Ridge Formation in order to produce an integrated and greatly refined set of biostratigraphic, chemostratigraphic, and sedimentological data. The new data support the interpretation offered by Palmer (1968) of the Jones Ridge strata as the product of deposition in outermost platform to upper slope environments offered by Palmer (1968) on the basis of taxonomic content of the faunas and close proximity of deep water units of equivalent age a very short distance to the southwest.

Alaska↗
USGS2012

Life on the edge: corals in mangroves and climate change

Coral diseases have played a major role in the degradation of coral reefs in the Caribbean, including those in the US Virgin Islands (USVI). In 2005, bleaching affected reefs throughout the Caribbean, and was especially severe on USVI reefs. Some corals began to regain their color as water temperatures cooled, but an outbreak of disease (primarily white plague) led to losses of over 60% of the total live coral cover. Montastraea annularis, the most abundant coral, was disproportionately affected, and decreased in relative abundance. The threatened species Acropora palmata bleached for the first time on record in the USVI but suffered less bleaching and less mortality from disease than M. annularis. Acropora palmata and M. annularis are the two most significant species in the USVI because of their structural role in the architecture of the reefs, the large size of their colonies, and their complex morphology. The future of the USVI reefs depends largely on their fate. Acropora palmata is more likely to recover than M. annularis for many reasons, including its faster growth rate, and its lower vulnerability to bleaching and disease.

Conference Paper↗
USGS2006

Reassessing a troublesome fact of mountain life: Avalanches in Glacier National Park

For the past decade, our U.S. Geological Survey (USGS) research team has rummaged through Glacier National Park’s archives looking for records of snow avalanches. Our searches have paid off. We have found photographs that show snow avalanches blocking progress during the annual spring opening of the famed Going-to-the-Sun Road, ranger logs that describe cabins and telephone lines destroyed by avalanches, and superintendents’ reports that recount avalanche accidents that killed employees or visitors. Recently, we have combined these historical sources with field studies to investigate whether snow avalanches in the park may be more cyclical than random and as much an ecological process as a natural hazard. Our ongoing research in Montana has yielded relevant information for park managers elsewhere who deal with avalanche threats to park infrastructure and for ecologists seeking a better understanding of how mountain ecosystems function. Our research has focused on two transportation corridors: the Going-to-the-Sun Road that bisects the center of the park, and John F. Stevens Canyon, at the park’s southwest corner ( fig. 1 ). The Going-to-the-Sun Road is the park’s most visited attraction; deep snow and avalanches force the road’s closure each winter, and in spring, park crews dig it out using bulldozers and other heavy equipment ( fig. 2 ). Springtime avalanches can bury workers or push equipment off the road and over cliffs ( figs. 3a and 3b ), as happened in 1953, when two workers died. Our research started with a study of how interannual variations in snowfall and avalanches affect the road opening. The initial study helped park managers predict and plan for the road opening in spring and respond to the many topical questions from park visitors and locals. More recent studies have focused on determining the conditions that create springtime avalanches, which are a poorly understood aspect of the avalanche phenomenon.

Wyoming↗
USGS1989

Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Pacific Northwest)--ghost and blue mud shrimp

Geographic range: The ghost shrimp is found in intertidal areas along the west coast of North America from Mutiny Bay, Alaska, to the mouth of the Tijuana River, San Diego County, California; MacGinitie (1934) and Ricketts and Calvin (1968) reported finding specimens as far south as El Estuario de Punto Banda, Baja California Norte, Mexico. The blue mud shrimp is found from southeastern Alaska to San Quentin Bay (Bahia de San Quentin) in Baja California Norte. The general distribution of the two species in the Pacific Northwest is identical (Figure 3).

California, Oregon, Washington↗
USGS2006

Potential risks of pesticide degradates to aquatic life

Recent advances in analytical methodology and greater access to analytical standards have led to the detection of degradates from a wide variety of pesticides and other compounds in surface water, ground water, precipitation, air, and sediment (Boxall and others, 2004). Many of these degradates are more persistent in the environment than their parent compounds, and many are more mobile, as well.

Report↗
USGS2005

Investigation of thiamine and PCB association with early life stage fry mortality in lake trout from northwestern Lake Michigan in 1996-1998

Lake trout ( Salvelinus namaycush ) eggs were collected from 72 females near Sturgeon Bay, WI in northwestern Lake Michigan from 1996, 1997, and 1998 to determine the relationships between egg thiamine and polychlorinated biphenyl (PCB) concentrations with egg fertilization and hatch, prevalence of abnormal fry, and fry mortality. Fry mortality consistent with early mortality syndrome (EMS) was observed in eggs from 33% of the females in 1996, 25% in 1997, and 28% in 1998. Among egg lots exhibiting EMS, fry mortality averaged 95% in 1996, 63% in 1997 and 77% in 1998 compared to 2% or less in lots that did not exhibit EMS. Expression of EMS was strongly correlated with egg thiamine concentrations; egg lots with less than approximately 1 nmol/g total thiamine consistently exhibited high rates of EMS, whereas egg batches with greater than 1.5 nmol/g showed little or no incidence of EMS among swim-up fry. Egg thiamine concentration was not related to fertilization rate, egg hatch, or the prevalence of abnormal fry. There was no relationship between egg concentrations of PCBs or tetrachlorinated dibenzo-p-dioxin (TCDD) equivalents (from PCBs, dioxins, and furans) and any of the egg or fry viability measurements, including EMS. We concluded that fry mortality observed in Lake Michigan lake trout in 1996-1998 was not caused by the toxicity of PCBs, dioxins, and furans, but is due to low egg thiamine concentrations.

Conference Paper↗