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USGS2018

Prospects for reconstructing paleoenvironmental conditions from organic compounds in polar snow and ice

Polar ice cores provide information about past climate and environmental changes over periods ranging from a few years up to 800,000 years. The majority of chemical studies have focused on determining inorganic components, such as major ions and trace elements as well as on their isotopic fingerprint. In this paper, we review the different classes of organic compounds that might yield environmental information, discussing existing research and what is needed to improve knowledge. We also discuss the problems of sampling, analysis and interpretation of organic molecules in ice. This review highlights the great potential for organic compounds to be used as proxies for anthropogenic activities, past fire events from different types of biomass, terrestrial biogenic emissions and marine biological activity, along with the possibility of inferring past temperature fluctuations and even large-scale climate variability. In parallel, comprehensive research needs to be done to assess the atmospheric stability of these compounds, their ability to be transported long distances in the atmosphere, and their stability in the archive in order to better interpret their fluxes in ice cores. In addition, specific decontamination procedures, analytical methods with low detection limits (ng/L or lower), fast analysis time and low sample requests need to be developed in order to ensure a good time resolution in the archive.

Quaternary Science Reviews↗

USGS2002

The Sea-Floor Mapping Facility at the U.S. Geological Survey Woods Hole Field Center, Woods Hole, Massachusetts

Researchers of the sea-floor mapping facility at the U.S. Geological Survey (USGS) Woods Hole Field Center in Woods Hole, Mass., use state-of-the-art technology to produce accurate geologic maps of the sea floor. In addition to basic bathymetry and morphology, sea-floor maps may contain information about the distribution of sand resources, patterns of coastal erosion, pathways of pollutant transport, and geologic controls on marine biological habitats. The maps may also show areas of human impacts, such as disturbance by bottom fishing and pollution caused by offshore waste disposal. The maps provide a framework for scientific research and provide critical information to decisionmakers who oversee resources in the coastal ocean.

Fact Sheet↗

USGS2010

Submarine groundwater discharge and fate along the coast of Kaloko-Honokohau National Historical Park, Island of Hawai`i: Part 3, spatial and temporal patterns in nearshore waters and coastal groundwater plumes, December 2003-April 2006

During seven surveys between December 2003 and April 2006, 1,045 depth profiles of surface water temperature and salinity were collected to examine variability in water column properties and the influence of submarine groundwater discharge (SGD) on the nearshore waters and coral reef complex of Kaloko-Honokōhau National Historical Park, Island of Hawai‘i. This effort was made to characterize the variability in nearshore water properties with seasonality and hydrodynamic forcing (tides, winds, and waves) and to determine the spatial and vertical extent of influence of SGD plumes on the Park’s marine biological resources. The results of this study reveal that nearshore waters of the Park were persistently influenced by plumes of submarine groundwater discharge that are generally colder, less saline, and more concentrated in nutrients than the surrounding seawater. These plumes extended between 100 and 1,000 m offshore to depths ranging between 1 and 5 m and often contained several million to hundreds of millions of gallons of brackish water. In essence, the Park’s nearshore, like much of the arid west coast of Hawai‘i, is estuarine. Although the groundwater plumes were persistent over the years studied, their spatial extent and volume varied tidally, seasonally, and annually. In one season, April 2004, an inverse relation of decreasing salinity with increasing temperature was found in the upper 5 m of the water column, unlike the other seasons, when surface water temperature and salinity were positively correlated. These data provide the first comprehensive record of nearshore water column properties within the Park boundaries and a baseline for detecting and assessing future conditions. Various resort, industrial, and municipal developments, either planned or under construction around the Park, will require significant groundwater supplies and will likely alter groundwater quantity and quality. The flux and quality of groundwater through the National Park are critical to the rare anchialine (brackish) pool ecosystems and various ecosystem functions of the nearshore waters and coral reefs. Changes in groundwater discharge are expected to have significant impacts to the area’s coastal ecosystems, including decreased freshwater outflow to the brackish anchialine pools and coral reefs and increased nutrient and contaminant concentrations. In conjunction with two complementary studies of this series (Parts 1 and 2), these data provide insight into the patterns of influence and fate of SGD in the Park’s coastal waters. This information is important for determining water-resource management strategies that balance the needs of the ecosystem with those of human livelihood. This report describes the data, presents the general findings, and gives representative examples of seasonal and tidal variability in water column properties and SGD-fed plumes across the Park’s nearshore waters.

Hawaii↗

USGS1987

The global carbon cycle and Quaternary paleoclimates.

Key evidence of ancient CO2 concentrations has come from studies of ice cores, marine sediments, ocean current patterns, and oceanic biochemistry and biota, but there are conflicting views about the role of the marine biological pump, especially as regards the deglacial increase in CO2.-from Author

Episodes↗

USGS2015

Integrating climate change into northeast and midwest State Wildlife Action Plans

The Department of Interior Northeast Climate Science Center (NE CSC) conducts research that responds to the regional natural resource management community’s needs to anticipate, monitor, and adapt to climate change. The NE CSC is supported by a consortium of partners that includes the University of Massachusetts Amherst, College of Menominee Nation, Columbia University, Marine Biological Laboratory, University of Minnesota, University of Missouri Columbia, and University of Wisconsin. The NE CSC also engages and collaborates with a diversity of other federal, state, academic, tribal, and non-governmental organizations (NGOs) to conduct collaborative, stakeholder-driven, and climate-focused work. The State Wildlife Action Plans (SWAPs) are revised every 10 years; states are currently working towards a target deadline of October 2015. SWAP coordinators have been challenged to incorporate climate change impacts and species responses into their current revisions. This synthesis is intended to inform the science going into Northeast and Midwest SWAPs across the 22 NE CSC states ranging from Maine to Virginia, and Minnesota and Missouri in the eastern United States. It is anticipated that this synthesis will help guide SWAP authors in writing specific sections, help revise and finalize existing sections, or be incorporated as an appendix or addendum. The purpose of this NE CSC-led cooperative report is to provide a synthesis of what is known and what is uncertain about climate change and its impacts across the NE CSC region, with a particular focus on the responses and vulnerabilities of Regional Species of Greatest Conservation Need (RSGCN) and the habitats they depend on. Another goal is to describe a range of climate change adaptation approaches, processes, tools, and potential partnerships that are available to State natural resource managers across the Northeast and Midwest regions of the United States. Through illustrative case studies submitted by the NE CSC and partners, we demonstrate climate change adaptation efforts being explored and implemented across local and large-landscape scales. This document is divided into four sections and addresses the following climate and management relevant questions: Climate Change in the Northeast and Midwest United States: How is the climate changing and projected to change across the Northeast and Midwest regions of the United States? Northeast and Midwest regional species and habitats at greatest risk and most vulnerable to climate impacts: What are the relative vulnerabilities of fish and wildlife species and their habitats to climate change in the Northeast and Midwest? Biological responses to climate impacts with a focus on Northeast and Midwest Regional Species of Greatest Conservation Need (RSGCN): How are threatened fish and wildlife likely to respond or adapt to climate change in the Northeast and Midwest? Scale-appropriate adaptation strategies and actions in the Northeast and Midwest United States: What approaches, strategies, and actions could be taken to sustain fish, wildlife and their habitats in the short and long term across the Northeast and Midwest? The outline and content for this document were developed with input from State Coordinators, members of the Northeast Association of Fish and Wildlife Agencies and Midwest Association of Fish and Wildlife Agencies, DOI Northeast Climate Science Center affiliated researchers, and other partners including the Landscape Conservation Cooperatives, the Northern Institute of Applied Climate Science, the Wildlife Conservation Society, and The Nature Conservancy. Terwilliger Consulting, Inc., was especially instrumental in helping connect and coordinate the authors of this report with State representatives through conference calls and email surveys to develop the most needed and effective information for current SWAP revisions. On a final note, the SWAPs are living documents that can be added to and evolve on timescales beyond the 10-year revision cycle. The development of this report was timed such that SWAP coordinators and writers would have sufficient time to implement this input before their October 2015 deadline. However, this document is also meant to serve as a starting point for coordinated and collaborative climate science and adaptation across the region; the NE CSC 5 endeavors to continue to provide actionable science during the coming years in collaboration with its diverse federal, state, NGO, and academic partners.

Connecticut, Delaware, Iowa, Illinois, Indiana, Ke↗

USGS2011

Shrimp trawlers as a local attractor of seabirds in nearshore waters of South Carolina, USA

Shrimp trawling is common throughout the southeastern and Gulf of Mexico coasts of the USA and is the primary contributor to fisheries discards in these regions. Tens of thousands of nearshore seabirds nest near shrimp trawling grounds in the USA, but to date, there has been no assessment of the relationship between seabirds and shrimp trawlers. We examined the taxonomic composition of bycatch, rate at which seabirds scavenged bycatch, and energy density of discarded bycatch in a nearshore commercial shrimp fishery. Bycatch was primarily comprised of demersal fish that are not typically accessible to the plunge-diving and surface-feeding seabirds that occur in the area. Hence, seabird diets in the region appear to be broadened taxonomically by the availability of discards. Results from discard experiments indicated that 70% of the nearly 5,500 items discarded by hand were scavenged by seabirds and that the fate of a discarded item was most strongly predicted by its taxonomic order. Laughing gulls scavenged the greatest proportion of discards, although brown pelicans were the only species to scavenge more discards than predicted based upon their abundance. Because this is the first such study in the region, it is difficult to ascertain the extent or intensity of the impact that discards have on nearshore seabirds. Nonetheless, our results suggest that it will be difficult for managers to clearly understand fluctuations in local seabird population dynamics without first understanding the extent to which these species rely upon discards. This may be especially problematic in situations where seabird populations are recovering following natural or anthropogenic stressors.

South Carolina↗

USGS1992

Experimental evidence for the effects of polyphenolic compounds from Dictyoneurum californicum Ruprecht (Phaeophyta: Laminariales) on feeding rate and growth in the red abalone Haliotus rufescens Swainson

The effects of polyphenolic compounds from brown algae on grazing and growth rate of the California red abalone Haliotis rufescens Swainson were examined. Abalone consumed three phenolic-poor algal species, Laminaria sinclarii (Harvey) Farlow, Macrocystis pyrifera Agardh, and Nereocystis luetkeana Postels et Ruprecht (mean phenolic content = 0.52% dry mass), at a greater rate than two phenolic-rich species, Dictyoneurum californicum Ruprecht and Cystoseira osmundacea Agardh (mean phenolic content = 4.60% dry mass). This inverse relationship between phenolic content and consumption rate also existed after the algae were macerated and the liquid portion of the blended slurry incorporated in agar discs. However, the correlation between grazing rate and phenolic content imprpve d in this latter experiment, thus suggesting that abalone grazing was deterred significantly by the morphology of L. sinclarii and, to a lesser extent, of M. pyrifera . Polyphenolics extracted from D. californicum reduced abalone grazing rates by 90% when incorporated into agar discs at a concentration of 6 mg·ml −1 . Although abalone were unable to maintain body mass when fed ad libitum on macerated M. pyrifera incorporated into agar discs, polyphenolics from D. californicum further inhibited shell growth when added to the discs at 5 mg·ml −1 . The abalone ate less of the phenol-containing discs than of the discs lacking phenolics. Our results support findings of several prior studies that polyphenolic compounds from brown algae deter grazing by coastal zone herbivores in the northeast Pacific Ocean.

Journal of Experimental Marine Biology and Ecology↗

USGS2021

Mapping biological soil crusts in a Hawaiian dryland

Historical and ongoing land use patterns in the Hawaiian Islands have degraded the Islands’ drylands, causing erosion and detrimentally affecting adjacent coastal marine ecosystems. Biological soil crust (biocrust) communities have been shown to increase soil stability in drylands worldwide, but their efficacy in mitigating soil erosion in Hawaiian drylands is largely unknown. Using a combination of field data and imagery collected by small unmanned aerial systems (sUAS), we mapped biocrusts and examined their influence on soil stability in the Kawaihae watershed, an erosion-prone dryland on leeward Hawai`i Island. We created classified maps of biocrust cover from imagery collected at three spatial resolutions (1.2, 2.1 and 2.8 cm/pixel) using the pixel-based Support Vector Machine (SVM) classifier and investigated the impacts of spatial resolution and biocrust level of development on classification accuracy. Our medium (2.1 cm) resolution image produced the highest overall classification accuracy when biocrust was treated as a single class (82.1%). We explored the spatial impacts of biocrusts on soil loss via sUAS-derived measurements of elevation change over a four-year time span. We found differences in soil loss among land cover types, but robustly quantifying these was a challenge, as much of the change fell below statistically significant limits of detection. We investigated the relationship between biocrust development and soil stability by conducting soil aggregate stability testing at the three biocrust levels of development (LODs) present at the study site. We found a significant increase in soil stability from soils without surface biocrusts (LOD score of 0) to those with biocrusts at any development level (LOD 1–3). Our research adds to the body of biocrust knowledge by presenting new information about biocrust distribution and soil stabilization capabilities in Hawaiian drylands. We also provide insights into the trade-offs between spatial resolution and classification accuracy for biocrust classification and land cover analysis.

Hawaii↗

USGS2011

OBIS-USA: a data-sharing legacy of the census of marine life

The United States Geological Survey's Biological Informatics Program hosts OBIS-USA, the US node of the Ocean Biogeographic Information System (OBIS). OBIS-USA gathers, coordinates, applies standard formats to, and makeswidely available data on biological collections in marine waters of the United States and other areas where US investigators have collected data and, in some instances, specimens. OBIS-USA delivers its data to OBIS international, which then delivers its data to the Global Biodiversity Information Facility (GBIF) and other Web portals for marine biodiversity data. OBIS-USA currently has 145 data sets from 36 participants, representing over 6.5 million occurrence records of over 83,000 taxa from more than 888,000 locations. OBIS-USA, a legacy of the decade-long (2001-2010) international collaborative Census of Marine Life enterprise, continues to add data, including those from ongoing Census projects. Among the many challenges in creating OBIS, including OBIS-USA, were developing a community of trust and shared valueamong data providers, and demonstrating to providers the value of making their data accessible to others. Challenges also posed by the diversity of data sets relevant tomarine biodiversity stored on thousands of computers, in a variety of formats, not all widely accessible, have been met in OBIS-USA by implementing a uniform standard and publishing platform that is easily accessible to a broad range of users.

Oceanography↗

USGS2019

Synopsis of research programs that can provide baseline and monitoring information for offshore energy activities in the Pacific region: Seabird and marine mammal surveys in the Pacific region

We assembled and tabulated information about marine bird and mammal research and monitoring programs that could provide data needed to support environmental risk assessments. This included identifying ongoing or completed research programs that contain information on species and habitats sensitive to offshore energy activities and that could provide baseline and monitoring data to understand and mitigate potential impacts of offshore energy development in the Southern California Planning Area, Washington-Oregon Planning Area, and the Hawaiian OCS of the Bureau of Ocean Energy Management (BOEM). When available, we also included information regarding programs in Alaska, but the catalog for Alaska is not comprehensive. We included programs that assessed the distribution, abundance, or biology of marine birds (seabirds, waterbirds, or sea ducks) and marine mammals (cetaceans, pinnipeds, and sea otters), some of which are protected species under the Endangered Species Act (ESA of 1973) or the Marine Mammal Protection Act (MMPA of 1972). We canvassed data providers with spreadsheet or web-based survey forms. The marine bird survey returned information on research and monitoring efforts for 28 parameters across 46 species from 36 entities. The marine mammal survey returned information on research and monitoring efforts for 24 parameters across 22 marine mammal species from 22 entities. We tabulated the parameters by species to show which parameters are most commonly measured and where there might be information gaps. Both marine bird and marine mammal research and monitoring are widespread throughout the Pacific, with 535 entries for marine mammals and 1,911 entries for marine birds. Although we provide summaries of key aspects within research and monitoring programs, the associated database can be further queried in several ways. Versioning of this database format essentially creates a “living database” that can be updated in the future as new information becomes available.

California, Oregon, Washington↗

USGS2019

Synopsis of research programs that can provide baseline and monitoring information for offshore energy activities in the Pacific region: Seabird and marine mammal surveys in the Pacific region

Alaska, California, Hawaii, Oregon, Washington↗

USGS2006

Anguilliform larvae collected off North Carolina

The distinctive larval stage of eels (leptocephalus) facilitates dispersal through prolonged life in the open ocean. Leptocephali are abundant and diverse off North Carolina, yet data on distributions and biology are lacking. The water column (from surface to 1,293 m) was sampled in or near the Gulf Stream off Cape Hatteras, Cape Lookout, and Cape Fear, North Carolina during summer through fall of 1999-2005, and leptocephali were collected by neuston net, plankton net, Tucker trawl, and dip net. Additional samples were collected nearly monthly from a transect across southern Onslow Bay, North Carolina (from surface to 91 m) from April 2000 to December 2001 by bongo and neuston nets, Methot frame trawl, and Tucker trawl. Overall, 584 tows were completed, and 224 of these yielded larval eels. The 1,295 eel leptocephali collected (combining all methods and areas) represented at least 63 species (nine families). Thirteen species were not known previously from the area. Dominant families for all areas were Congridae (44% of individuals, 11 species), Ophichthidae (30% of individuals, 27 species), and Muraenidae (22% of individuals, ten species). Nine taxa accounted for 70% of the overall leptocephalus catches (in order of decreasing abundance): Paraconger caudilimbatus (Poey), Gymnothorax ocellatus Agassiz complex, Ariosoma balearicum (Delaroche), Ophichthus gomesii (Castelnau), Callechelys muraena Jordan and Evermann, Letharchus aliculatus McCosker, Rhynchoconger flavus (Goode and Bean), Ophichthus cruentifer (Goode and Bean), Rhynchoconger gracilior (Ginsburg). The top three species represented 52% of the total eel larvae collected. Most leptocephali were collected at night (79%) and at depths > 45 m. Eighty percent of the eels collected in discrete depth Tucker trawls at night ranged from mean depths of 59-353 m. A substantial number (38% of discrete depth sample total) of larval eels were also collected at the surface (neuston net) at night. Daytime leptocephalus distributions were less clear partly due to low catches and lower Tucker trawl sampling effort. While net avoidance may account for some of the low daytime catches, an alternative explanation is that many species of larval eels occur during the day at depths > 350 m. Larvae of 21 taxa of typically shallow water eels were collected at depths > 350 m, but additional discrete depth diel sampling is needed to resolve leptocephalus vertical distributions. The North Carolina adult eel fauna (estuary to at least 2,000 m) consists of 51 species, 41% of which were represented in these collections. Many species of leptocephali collected are not yet known to have juveniles or adults established in the South Atlantic Bight or north of Cape Hatteras. Despite Gulf Stream transport and a prolonged larval stage, many of these eel leptocephali may not contribute to their respective populations. ?? 2006 Springer-Verlag.

Marine Biology↗

USGS2007

An evaluation of the effects of conservation and fishery enhancement hatcheries on wild populations of salmon

The historical, political and scientific aspects of salmon hatchery programmes designed to enhance fishery production, or to recover endangered populations, are reviewed. We start by pointing out that the establishment of hatcheries has been a political response to societal demands for harvest and conservation; given this social context, we then critically examined the levels of activity, the biological risks, and the economic analysis associated with salmon hatchery programmes. A rigorous analysis of the impacts of hatchery programmes was hindered by the lack of standardized data on release sizes and survival rates at all ecological scales, and since hatchery programme objectives are rarely defined, it was also difficult to measure their effectiveness at meeting release objectives. Debates on the genetic effects of hatchery programmes on wild fish have been dominated by whether correct management practices can reduce negative outcomes, but we noted that there has been an absence of programmatic research approaches addressing this important issue. Competitive interactions between hatchery and wild fish were observed to be complex, but studies researching approaches to reduce these interactions at all ecological scales during the entire salmon life history have been rare, and thus are not typically considered in hatchery management. Harvesting of salmon released from fishery enhancement hatcheries likely impacts vulnerable wild populations; managers have responded to this problem by mass marking hatchery fish, so that fishing effort can be directed towards hatchery populations. However, we noted that the effectiveness of this approach is dependant on accurate marking and production of hatchery fish with high survival rates, and it is not yet clear whether selective fishing will prevent overharvest of wild populations. Finally, research demonstrating disease transmission from hatchery fish to wild populations was observed to be equivocal; evidence in this area has been constrained by the lack of effective approaches to studying the fate of pathogens in the wild. We then reviewed several approaches to studying the economic consequences of hatchery activities intended to inform the social decisions surrounding programmes, but recognized that placing monetary value on conservation efforts or on hatcheries that mitigate cultural groups’ loss of historical harvest opportunities may complicate these analyses. We noted that economic issues have rarely been included in decision making on hatchery programmes. We end by identifying existing major knowledge gaps, which, if filled, could contribute towards a fuller understanding of the role that hatchery programmes could play in meeting divergent goals. However, we also recognized that many management recommendations arising from such research may involve trade-offs between different risks, and that decisions about these trade-offs must occur within a social context. Hatcheries have played an important role in sustaining some highly endangered populations, and it is possible that reform of practices will lead to an increase in the number of successful programmes. However, a serious appraisal of the role of hatcheries in meeting broader needs is urgently warranted and should take place at the scientific, but more effectively, at the societal level.

Advances in Marine Biology↗

USGS1992

Measurement of filtration rates by infaunal bivalves in a recirculating flume

A flume system and protocol for measuring the filtration rate of infaunal bivalves is described. Assemblages of multi-sized clams, at natural densities and in normal filter-feeding positions, removed phytoplankton suspended in a unidirectional flow of water. The free-stream velocity and friction velocity of the flow, and bottom roughness height were similar to those in natural estuarine waters. Continuous variations in phytoplankton (Chroomonas salinay) cell density were used to measure the filtration rate of the suspension-feeding clam Potamocorbula amurensis for periods of 2 to 28 h. Filtration rates of P. amurensis varied from 100 to 580 liters (gd)-1 over a free-stream velocity range of 9 to 25 cm s-1. Phytoplankton loss rates were usually constant throughout the experiments. Our results suggest that suspension-feeding by infaunal bivalves is sensitive to flow velocity. ?? 1992 Springer-Verlag.

Marine Biology↗

USGS1995

Species-specific patterns of hyperostosis in marine teleost fishes

The occurrence of swollen or hyperostotic bones in skeletal preparations, preserved museum material or whole fresh specimens of marine teleost fishes was identified in 92 species belonging to 22 families. Patterns of hyperostotic skeletal growth were typically consistent and often species-specific in all individuals larger than a certain size. The taxonomic distribution of hyperostosis in diverse phylogenetic groups suggests that it has arisen independently many times. Selected bones from two species of the family Carangidae, horse-eye jack Caranx latus Agassiz and crevalle jack Caranx hippos (Linnaeus), were examined in detail by light and electron microscopy. Nonhyperostotic bone contained osteoid-producing osteoblasts, resorbing osteoclasts, occasional osteocytes, and a rich vascular network, all characteristics of cellular bone. Thus, these fishes have a spatial juxtaposition of cellular and acellular bone tissues in adjacent and often serially homologous bone sites. The functional significance of hyperostosis is unknown, but it is a predictable manifestation of bone growth and development for the many taxa in which it occurs.

Marine Biology↗

USGS1994

Genetic population structure of the recently introduced Asian clam, Potamocorbula amurensis , in San Francisco Bay

The genetic population structure of the recently introduced Asian clam, Potamocorbula amurensis , in San Francisco Bay was described using starch gel electrophoresis at eight presumptive loci. Specimens were taken from five environmentally distinct sites located throughout the bay. The population maintains a high degree of genetic variation, with a mean heterozygosity of 0.295, a mean polymorphism of 0.75, and an average of 3.70 alleles per locus. The population is genetically homogeneous, as evidenced from genetic distance values and F -statistics. However, heterogeneity of populations was indicated from a contingency chi-square test. Significant deviations from Hardy-Weinberg equilibrium and heterozygote deficiencies were found at the Lap-1 locus for all populations and at the Lap-2 locus for a single population. High levels of variability could represent a universal characteristic of invading species, the levels of variability in the source population(s), and/or the dynamics of the introduction. Lack of differentiation between subpopulations may be due to the immaturity of the San Francisco Bay population, the “general purpose” phenotype genetic strategy of the species, high rates of gene flow in the population, and/or the selective neutrality of the loci investigated.

California↗

USGS1987

The importance of methane and thiosulfate in the metabolism of the bacterial symbionts of two deep-sea mussels

Undescribed hydrocarbon-seep mussels were collected from the Louisiana Slope, Gulf of Mexico, during March 1986, and the ultrastructure of their gills was examined and compared to Bathymodiolus thermophilus, a mussel collected from the deep-sea hydrothermal vents on the Gala??pagos Rift in March 1985. These closely related mytilids both contain abundant symbiotic bacteria in their gills. However, the bacteria from the two species are distinctly different in both morphology and biochemistry, and are housed differently within the gills of the two mussels. The symbionts from the seep mussel are larger than the symbionts from B. thermophilus and, unlike the latter, contain stacked intracytoplasmic membranes. In the seep mussel three or fewer symbionts appear to be contained in each host-cell vacuole, while in B. thermophilus there are often more than twenty bacteria visible in a single section through a vacuole. The methanotrophic nature of the seep-mussel symbionts was confirmed in 14C-methane uptake experiments by the appearance of label in both CO2 and acid-stable, non-volatile, organic compounds after a 3 h incubation of isolated gill tissue. Furthermore, methane consumption was correlated with methanol dehydrogenase activity in isolated gill tissue. Activity of ribulose-1,5-biphosphate (RuBP) carboxylase and 14CO2 assimilation studies indicate the presence of either a second type of symbiont or contaminating bacteria on the gills of freshly captured seep mussels. A reevaluation of the nutrition of the symbionts in B. thermophilus indicates that while the major symbiont is not a methanotroph, its status as a sulfur-oxidizing chemoautotroph, as has been suggested previously, is far from proven. ?? 1987 Springer-Verlag.

Marine Biology↗

USGS1977

Physiological characteristics of mercury uptake by two estuarine species

Rapid uptake and slow loss of Hg will result from short exposures of some organisms to this metal, due to the transformation of Hg to a slowly exchanging form within the organisms. The extent of the difference between exposure time and depuration time will depend upon the rate of transformation during uptake. For the polychaete worm Neanthes succinea and the shrimp Palaemon debilis such transformations are extremely rapid. The exchange of Hg from the slowly exchanging compartment is similar among a wide variety of species. Thus, interspecies differences in susceptibility to Hg may be determined by differences in biochemical transformation rates and physiological permeability to the metal. ?? 1977 Springer-Verlag.

Marine Biology↗