National Marine Fisheries Service

About: National Marine Fisheries Service is a government organization based out in Silver Spring, Maryland, United States. It is known for research contribution in the topics: Population & Fisheries management. The organization has 3949 authors who have published 7053 publications receiving 305073 citations. The organization is also known as: NOAA Fisheries & NOAA National Marine Fisheries Service.

Target-strength measurements of walleye pollock (Theragra chalcogramma) and Pacific whiting (Merluccius productus)

Abstract: The importance of knowledge about the target-strength (TS) characteristics of the surveyed fish population to the accuracy of acoustic assessments using echo integration is well known. The most commonly used TS to length (L) relationship for walleye pollock is based on swimbladder morphology measurements and in situ TS measurements TS (in dB)=20 log L−66.0 for fish length in centimeters. For Pacific whiting, TS measurements have not been made over an adequate range of fish lengths to determine the appropriate relationship for use in scaling echo-integration surveys. However, results presented in this paper and elsewhere suggest a smaller TS (about 2 dB for a given length) for 40-60 cm fish. Measurements of the TS of walleye pollock and Pacific whiting were made with a SIMRAD EK500 in the present study. The appropriateness of the currently used TS to length relationship for echo integration scaling is discussed for pollock. The application of a TS to length relationship for Pacific whiting is considered. An attempt to use a system with a transducer lowered through the water column to reduce noise-induced bias is described.

Host population genetic structure and zooxanthellae diversity of two reef-building coral species along the Florida Reef Tract and wider Caribbean

Abstract: In preparation for a large-scale coral restoration project, we surveyed host population genetic structure and symbiont diversity of two reef-building corals in four reef zones along the Florida reef tract (FRT). There was no evidence for coral population subdivision along the FRT in Acropora cervicornis or Montastraea faveolata based on microsatellite markers. However, in A. cervicornis, significant genetic differentiation was apparent when extending the analysis to broader scales (Caribbean). Clade diversity of the zooxanthellae differed along the FRT. A. cervicornis harbored mostly clade A with clade D zooxanthellae being prominent in colonies growing inshore and in the mid-channel zones that experience greater temperature fluctuations and receive significant nutrient and sediment input. M. faveolata harbored a more diverse array of symbionts, and variation in symbiont diversity among four habitat zones was more subtle but still significant. Implications of these results are discussed for ongoing restoration and conservation work.

A Process-Based View of Floodplain Forest Patterns in Coastal River Valleys of the Pacific Northwest

Abstract: Floodplains in the Pacific Coastal Ecoregion (PCE) stem from steep eroding mountain landscapes in a rain forest environment, and sustain a rich array of natural resources. Like floodplains elsewhere, many of the approximately 200 coastal river valleys are profoundly altered by flow regulation and land conversion for agriculture and urban development, and these activities have contributed to widespread declines in anadromous fishes and environmental quality. Some of the coastal river valleys, however, still retain many of their natural features, thereby providing important reference sites. Understanding fundamental biophysical processes underpinning natural floodplain characteristics is essential for successfully protecting and restoring ecological integrity, including inherent goods and services. This article examines factors underpinning the ecological characteristics of PCE floodplains, particularly riparian soils and trees. Drawing on over two decades of research and literature, we describe the spatial and temporal characteristics of physical features for alluvial PCE floodplains, examine the importance of sediment deposition and associated biogeochemical processes in floodplain soil formation, quantify vegetative succession and production dynamics of riparian trees, discuss how epiphytes, marine-derived nutrients, and soil processes contribute to tree production, describe the roles and importance of large dead wood in the system, the role of termites in its rapid decomposition, and show how large wood contributes to vegetative succession. These highly interconnected features and associated processes are summarized in a model of system-scale drivers and changes occurring over several centuries. Collectively, this integrated perspective has strong implications for floodplain rehabilitation, and we identify appropriate metrics for evaluating floodplain condition and functions. We draw heavily from our own experience on several well-studied rivers, recognizing additional studies are needed to evaluate the generality of concepts presented herein. As in any complex adaptive system, fundamental uncertainties remain and constraints imposed by the legacies of past human actions persist. Nevertheless, the evolving knowledge base is improving conservation strategies of lightly modified floodplains and is supporting the incorporation of emerging process-based perspectives into the rehabilitation of heavily modified systems.

DNA as a solar dosimeter in the ocean.

Abstract: Stratospheric ozone depletion may result in increased solar UV-B radiation to the ocean's upper layers and may cause deleterious effects on marine organisms. The primary UV-B damage induced in biological systems is to DNA. While physical measurements of solar UV-B penetration into the sea have been made, the effective depth and magnitude of actual DNA damage have not been determined. In the experiments reported here, UV-B-induced photoproducts (cyclobutane pyrimidine dimers) have been quantified in DNA molecules exposed to solar UV at the surface and at various depths in clear, tropical marine waters off Lee Stocking Island (23 degrees 45' N, 76 degrees 0.7' W), Exuma Cays, Bahamas. (14C)thymidine-labeled DNA or unlabeled bacteriophage phi X174 DNA was placed in specially designed quartz tubes at various depths for up to five days. Following exposure, DNA samples were removed to the laboratory where UV-B-induced pyrimidine dimers were quantified using a radiochromatographic assay, and bacteriophage DNA inactivation by solar UV-B was assayed by plaque formation in spheroplasts of Escherichia coli. Pyrimidine dimer induction was linear with time but the accumulation of dimers in DNA with time varied greatly with depth. Attenuation of dimer formation with depth of water was exponential. DNA at 3 m depth had only 17% of the pyrimidine dimers found at the surface. Bacteriophage phi X174 DNA, while reduced 96% in plaque-forming ability by a one day exposure to solar UV at the surface of the water, showed no effect on plaque formation after a similar exposure at 3 m. The data collected at the water's surface showed a "surface-enhanced dose" in that DNA damages at the real surface were greater than at the imaginary surface, which was obtained by extrapolating the data at depth to the surface. These results show the sensitivity of both the biochemical (dimers) and biological (phage plaques) DNA dosimeters. DNA dosimeters offer a sensitive, convenient and relatively inexpensive monitoring system, having both biochemical and biological endpoints for monitoring the biologically effective UV-B flux in the marine environment. Unlike physical dosimeters, DNA dosimeters do not have to be adjusted for biological effectiveness since they are sensitive only to DNA-mediated biologically effective UV-B radiation. Results of pyrimidine dimer induction in DNA by solar UV accurately predicted UV doses to the phage DNA.

Geographic and ontogenetic variation in the diet and daily ration of the bonnethead shark, Sphyrna tiburo, from the eastern Gulf of Mexico

Abstract: To examine variation in diet and daily ration of the bonnethead shark, Sphyrna tiburo (Linnaeus 1758), animals were collected from three areas in the eastern Gulf of Mexico: northwest Florida (∼29°40′N, 85°13′W), Tampa Bay near Anclote Key (∼28°10′N, 82°42.5′W), and Florida Bay (∼24°50′N, 80°48′W) from March through September, 1998–2000. In each area, diet was assessed by life stage (young-of-the year, juveniles, and adults) and quantified using five indices: percent by number (%N), percent by weight (%W), frequency of occurrence (%O), index of relative importance expressed on a percent basis (%IRI), and %IRI based on diet category (%IRIDC). Diet could not be assessed for young-of-the-year in Tampa Bay or Florida Bay owing to low sample size. Diet analysis showed an ontogenetic shift in northwest Florida. Young-of-the-year stomachs from northwest Florida (n = 68, 1 empty) contained a mix of seagrass and crustaceans while juvenile stomachs (n = 82, 0 empty) contained a mix of crabs and seagrass and adult stomachs (n = 39, 1 empty) contained almost exclusively crabs. Crabs made up the majority of both juvenile and adult diet in Tampa Bay (n = 79, 2 empty, and n = 88, 1 empty, respectively). Juvenile stomachs from Florida Bay (n = 72, 0 empty) contained seagrass and a mix of crustaceans while adult stomachs contained more shrimp and cephalopods (n = 82, 3 empty). Diets in northwest Florida and Tampa Bay were similar. The diet in Florida Bay was different from those in the other two areas, consisting of fewer crabs and more cephalopods and lobsters. Plant material was found in large quantities in all stomachs examined from all locations (>15 %IRIDC in 6 of the 7 life stage-area combinations, >30 %IRIDC in 4 of the 7 combinations, and 62 %IRIDC in young-of-the-year diet in northwest Florida). Using species- and area-specific inputs, a bioenergetic model was constructed to estimate daily ration. Models were constructed under two scenarios: assuming plant material was and was not part of the diet. Overall, daily ration was significantly different by sex, life stage, and region. The bioenergetic model predicted increasing daily ration with decreasing latitude and decreasing daily ration with ontogeny regardless of the inclusion or exclusion of plant material. These results provide evidence that bonnetheads continuously exposed to warmer temperatures have elevated metabolism and require additional energy consumption to maintain growth and reproduction.