Mussels document loss of bioavailable polycyclic aromatic hydrocarbons and the return to baseline conditions for oiled shorelines in Prince William Sound, Alaska

Polycyclic aromatic hydrocarbons (PAH) were measured in mussels (Mytilus trossulus) collected between 1990 and 2002 from 11 sites on the shores of Prince William Sound (PWS), Alaska, that were heavily oiled by the 1989 Exxon Valdez oil spill (EVOS). This study, utilizing the methods of the NOAA Status and Trends Mussel Watch Program, found that concentrations of PAH released from spill remnants have decreased dramatically with time and by 2002 were at or near the range of total PAH (TPAH) of 3-355 ng/g dry weight obtained for mussels from unoiled reference sites in PWS. Time-series TPAH data indicate a mean TPAH half-life in mussel tissues of 2.4 years with a range from 1.4 to 5.3, yielding an annual mean loss of bioaccumulated TPAH of 25%. The petroleum-derived TPAH fraction in mussel tissues has decreased with time, reflecting the decreasing release of EVOS residues in shoreline sediments. These results show that PAH from EVOS residues that remain buried in shoreline sediments after the early 1990s are in a form and at locations that have a low accessibility to mussels living in the intertidal zone.     

Effects of benzene and dimethylnaphthalene on homeostatic processes in two species of crabs

Long-term exposure of animals to sub-lethal doses of toxicants such as benzene (B) and dimethylnaphthalene (DMN) may result in subtle changes in their physiology and biochemistry. In crustaceans such changes include decreased rate of limb regeneration, extended time to molt and decreased growth increment at molt.^1,2 These processes depend upon an adequate supply of stored nutrients in the tissues and appropriate release of neuroendocrine substances from the central nervous system.^3,4 We are examining the effects of sub-lethal doses of B and DMN on osmotic and ionic regulation and on nutrient storage in the blue crab, Callinectes sapidus, and the green crab, Carcinus maenas. Disturbances in these physiological processes may reflect alterations in neuroendocrine functions brought about by the presence of toxicants. We find that exposure of C. maenas to B or DMN, followed by transfer to a dilute medium, results in impaired osmoregulatory capacity, while addition of these compounds to a dilute medium to which the animal is already acclimated does not affect their regulatory ability. Storage of carbohydrate in the midgut gland (hepatopancreas) is decreased by B or DMN, while the accessory storage tissues (gill, muscle) are not significantly affected.     

Environmental overview of Eckernförde Bay,northern Germany

This environmental overview of Eckernförde Bay (northern Germany) summarizes the results of previous studies relevant to the Office of Naval Research's Coastal Benthic Boundary Layer (CBBL) Baltic field exercise conducted during 1993–1994. Significant environmental characteristics include the following: (1) surface sediment distribution is related to water depth, dictated primarily by hydrodynamic reworking of older glacial deposits; (2) the origin and characteristics of small-scale sedimentary structures depend on storm-generated waves and currents; (3) the proximity of the sea surface and sediment —water interface results in a pelagic—benthic coupling that drives biogeochemical processes and produces organicrich, acoustically turbid sediments; and (4) the bay floor is complicated topographically by pockmarks and manmade sedimentary structures.     

Voracious planktonic hydroids: unexpected predatory impact on a coastal marine ecosystem

Hydroids are typically attached, benthic cnidarians that feed on a variety of small prey. During sampling on Georges Bank in spring 1994, we found huge numbers of hydroids suspended in the plankton. They fed on young stages of copepods that are an important prey for fish, as well as on young fish themselves. Two independent methods were used to estimate feeding rates of the hydroids; both indicate that the hydroids are capable of consuming from 50% to over 100% of the daily production of young copepods. These results suggest that hydroids can have a profound effect on the population dynamics of zooplankton and young fish on Georges Bank.     

Relative abundance, age, growth, and fecundity of grubby Myoxocephalus aenaeus in Niantic River and Niantic Bay, Long Island Sound

Grubby (Myoxocephalus aenaeus, Cottidae) is a common benthic fish of inshore waters and estuaries of eastern Long Island Sound; however, little information exists on their life history or population demographics. This study utilised a long-term data series (1976–2002) to assess grubby life history and population demographics and explores trends in the Niantic River and Niantic Bay populations. In addition, we examined the age, size, and fecundity of adult grubby in 2001–02 to determine the population characteristics in the region. Mean grubby catch per unit effort (CPUE) in Niantic Bay ranged from 0.4 per trawl in 1976 to 2.9 per trawl in 1984 while river CPUE ranged from 0.4 per trawl in 1977 to 7.6 per trawl in 1989. Catch of grubby in bottom trawls varied seasonally with highest CPUE occurring in winter. Highest entrainment of grubby larvae occurred in 2001 while the lowest entrainment observed was in 1991. Four age classes, 0+ through III+, were derived from otolith analysis (N = 51) although length frequency analysis suggested the possibility of older fish in the population. The total number of eggs in ovaries ranged from 286 to 16 451 for grubby (N = 64) between 52 mm and 155 mm TL. Results of this study indicated a decline in abundance of adult grubby over the 26-year period, possibly related to concurrent declines in eelgrass (Zostera marina) abundance and/or increased water temperature.     

Variability in the nutritional value of the major copepods in Cape Cod Bay (Massachusetts, USA) with implications for right whales

The North Atlantic right whale, a seriously endangered species, is found in Cape Cod Bay (Massachusetts, USA) during the winter and early spring. During their residency in these waters, these whales are frequently observed feeding. This study evaluated spatial and temporal changes in the chemical composition (carbon weight and C/N ratio) of the food resource targeted by the right whales in Cape Cod Bay. The three taxa measured (Centropages typicus, Pseudocalanus spp., and Calanus finmarchicus) had highly variable chemical compositions resulting from the different life strategies and from fluctuations in their surrounding environment. The impact of seasonal variability in the energy densities of the food resource of right whales was calculated and compared to the energetic requirements of these whales. Calculations indicated that differences in the nutritional content of the zooplankton prey in Cape Cod Bay could have a considerable effect on the nutrition available to the right whales. Therefore, it is likely that using more precise estimates of the energetic densities of the prey of right whales would lead to a re‐evaluation of the adequacy of the food resource available to these whales in the North Atlantic.     

Heavy metal analyses in the marine environment - approaches to quality control

The validity of analyses of elements in the femto- and picomolar ranges in waters and sediments can be assessed on the basis of several criteria: an evaluation of the chemical technique; the use of primary standards and intercalibration exercises; and chemical and geochemical coherence of the results. Herein are reported analyses of ruthenium, platinum, palladium, rhenium, iridium and gold in oceanic samples. The gold concentrations in surface seawaters, at least 25 times less than those previously reported, are in accord with the concentrations of their periodic table neighbors as well as with crustal and sedimentary contents. The remarkable concentration of rhenium in seawater, in relation to its very low crustal abundance, can be explained by the inertness of the perrhenate ion.