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At least 793 records · Page 44Linked to original sources
USGS1984

Carbonate and organic-carbon cycles and the history of upwelling at Deep Sea Drilling Project Site 532, Walvis Ridge, South Atlantic Ocean

Detailed carbonate and organic-carbon stratigraphies were constructed from samples collected every 20 cm in a 250-m hydraulic piston core recovered at DSDP Site 532 on Walvis Ridge. This sampling interval represents about one sample every 5000 yr., based on sediment accumulation rates calculated from nannofossil biostratigraphic zones. All samples were analyzed for percent CaCO 3 , resulting in a detailed carbonate stratigraphy for the past 5.0 m.y. The samples for the top 110 m of section were also analyzed for organic carbon in order to construct a detailed organiccarbon stratigraphy for the last 2.5 m.y. The recovered section has distinct dark-light color cycles with average periodicities of 55, 58, and 30 k.y. for the Quaternary, upper Pliocene, and lower Pliocene, respectively. Periodicities of carbonate cycles are similar to the color cycles; most carbonate minima correspond to the dark parts of color cycles. The average periodicity for carbonate cycles is about 36 k.y. Darker parts of color cycles usually contain higher concentrations of organic carbon, but the organic-carbon record does not follow the cyclicity of the color cycles in detail, at least for the last 2.5 m.y. Organic-carbon cycles have an average periodicity of about 34 k.y. for the Quaternary and upper Pliocene. The cycles of CaCO 3 and color have periodicities similar to those reported from carbonate stratigraphies from the northeast Atlantic, Caribbean, and eastern equatorial Pacific. The carbonate cycles at Site 532 are the result of external forcing, probably related to global climate, that affected fluctuations in both sediment supply from the African continental margin and productivity of siliceous organisms. The organic-carbon cycles have similar periodicities and similar changes in periodicities to those of the CaCO 3 cycles. Semiquantitative estimates of diatom abundance from smear slides and concentrations of biogenic SiO 2 calculated from chemical analyses suggest that upwelling at Site 532 was minor until about 3 m.y. ago. The Benguela-Current upwelling system either began at that time or, more likely, migrated into the area of Site 532, where it prevailed until some time between about 1.2 and 0.5 m.y. ago. The increase and decline of upwelling in the area of Site 532, however, did not disturb the trend of cyclicities of carbonate and organic carbon. The latest change in conditions at Site 532 was an increase in intensity of bottom currents during the past 0.5 m.y. that winnowed nannofossils, diatoms, and clay and left a lag deposit represented by a foraminifer-rich fades

Initial Reports of the D.S.D.P.↗
USGS1994

Why is the ocean salty?

All water, even rain water, contains dissolved chemicals which scientists call "salts." But not all water tastes salty. Water is fresh or salty according to individual judgment, and in making this decision man is more convinced by his sense of taste than by a laboratory test. It is one's taste buds that accept one water and reject another.

General Interest Publication↗
USGS2005

Resource inventory of marine and estuarine fishes of the West Coast and Alaska: A checklist of North Pacific and Arctic Ocean species from Baja California to the Alaska - Yukon border

This is a comprehensive inventory of the fish species recorded in marine and estuarine waters between the Alaska–Yukon Territory border in the Beaufort Sea and Cabo San Lucas at the southern end of Baja California and out about 300 miles from shore. Our westernmost range includes the eastern Bering Sea and Aleutian Islands. In addition, we have also included our best impressions of the species that might reasonably be expected to be members of the West Coast ichthyofauna but have not yet been captured or reported within our study area. These species are marked with an asterisk (*) and have been reported (1) in the western Bering Sea; (2) off Canada’s Yukon Territory and adjacent portions of the Northwest Territories; (3) along the southern-eastern tip (non-Pacific side) of Baja California; and (4) in waters somewhat beyond 300 miles from shore. Although the term West Coast usually refers to the coast of the continuous western states, our usage herein means the entire study area. The West Coast inventory within this range encompasses fish fauna from 44 orders, 232 families, and a minimum of 1,450 species. Please note that introduced and invasive fish species are marked by double asterisks (**) and that their scientific names are highlighted in gray. We have compiled this document because the most geographically inclusive previous inventories (Jordan and Evermann 1896a, Jordan et al. 1930) are largely of historical interest and are out of date. More recent lists and compilations have either focused on relatively narrow taxonomic groups (e. g., Kramer et al. 1995, Love et al. 2002), are regional in scope (e. g., Hart 1973, Hubbs et al. 1979, Mecklenburg et al. 2002), or focus on commonly observed species (e. g., Miller and Lea 1972, Eschmeyer and Herald 1983). With the explosion of coastal research and environmental assessments, beginning in the 1970s, and more recently, renewed scientific interest in biodiversity (e.g., effects of global climate change), our own studies on related subjects regarding fish populations, assemblages, and biological habitats, suggested this was the appropriate time to update and summarize our knowledge.

Report↗
USGS2010

U.S. Geological Survey (USGS) Western Region Kasatochi Volcano Coastal and Ocean Science

Alaska is noteworthy as a region of frequent seismic and volcanic activity. The region contains 52 historically active volcanoes, 14 of which have had at least one major eruptive event since 1990. Despite the high frequency of volcanic activity in Alaska, comprehensive studies of how ecosystems respond to volcanic eruptions are non-existent. On August 7, 2008, Kasatochi Volcano, in the central Aleutian Islands, erupted catastrophically, covering the island with ash and hot pyroclastic flow material. Kasatochi Island was an annual monitoring site of the U.S. Fish and Wildlife Service, Alaska Maritime National Wildlife Refuge (AMNWR); therefore, features of the terrestrial and nearshore ecosystems of the island were well known. In 2009, the U.S. Geological Survey (USGS), AMNWR, and University of Alaska Fairbanks began long-term studies to better understand the effects of the eruption and the role of volcanism in structuring ecosystems in the Aleutian Islands, a volcano-dominated region with high natural resource values.

Fact Sheet↗
USGS2011

From ridge to reef—linking erosion and changing watersheds to impacts on the coral reef ecosystems of Hawai‘i and the Pacific Ocean

Coral reef ecosystems are threatened by unprecedented watershed changes in the United States and worldwide. These ecosystems sustain fishing and tourism industries essential to the economic survival of many communities. Sediment, nutrients, and pollutants from watersheds are increasingly transported to coastal waters, where these contaminants damage corals. Although pollution from watersheds is one of many factors threatening coral survival, it is one that local people can have a profound influence on. U.S. Geological Survey scientists are using mapping, monitoring, and computer modeling to better forecast the effects of watershed changes on reef health. Working with communities in Hawai‘i and on other U.S. islands in the Pacific, they are helping to provide the science needed to make informed decisions on watershed and coral reef management.

Hawai'i↗