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.     

Estrogenic responses to xenobiotics in channel catfish (Ictalwus punctatus)

Several environmentally relevant contaminants are characterized as xenoestrogens by virtue of their ability to induce responses similar to 17β-estradiol (E2). There is concern that exposure to these xenoestrogens may result in endocrine and, thus, reproductive disruption. The objective of the present research was to determine whether xenobiotics known to elicit estrogenic responses in mammals were estrogenic in channel catfish, and if these compounds were capable of altering normal physiological response to E2. Sexually immature catfish were exposed by intraperitoneal injection to E2, suspected xenoestrogens or combination doses of E2 and xenoestrogen. Appearance of vitellogenin (Vg) in serum was used as the bioindicator of estrogenicity; Vg was measured by ELISA 7 days after injection. The ED₅₀ of E2 for the appearance of Vg in blood, 0.6 mg/kg, was used as the positive control. Synthetic estrogens, ethinylestradiol, mestranol and DES were effective in inducing Vg; the antiestrogen tamoxifen inhibited response to E2 when given in a combination dose. Treatment by both methoxychlor and p-nonylphenol resulted in Vg appearance in serum; the doses required were 300 times that of E2, and the vitellogenic response was less when compared to the E2-induced response. In addition, a combination dose of methoxychlor with E2 decreased the magnitude of the response to E2. Other mammalian xenoestrogens, o,p′-DDT, chlordecone, lindane and β-HCH, were not able to produce a vitellogenic response in this study.     

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.     

Modern swathe sounding and sub-bottom profiling technology for research applications: The Atlas Hydrosweep and Parasound Systems

This chapter describes two separate but complementary research echosounder systems originally developed by Krupp Atlas Elektronik GmbH for the new German oceanographic research vessel Meteor.The Hydrosweep is a Hydrographic wide-swathe sweep survey echosounder for both shallow and deep water applications providing accurate bathymetric surveys and terrain-following navigation capabilities.The Parasound system is a hull-mounted dual channel parametric narrow-beam deep sea survey and sub-bottom profiling echosounder enabling particularly high vertical and horizontal resolution of seabed features.     

The distributions of particulate atmospheric trace metals and mineral aerosols over the Indian Ocean

Data are presented for the concentrations of Al, Fe, Mn, Ni, Co, Cr, V, Cu, Zn, Pb and Cd in aerosols collected over two contrasting regions of the Indian Ocean. These are: (1) the northern Arabian Sea (AS), from which samples were collected in the northeast monsoon, during which the region receives an input of crustal material from the surrounding arid land masses; and (2) the Tropical Southern Indian Ocean (TSIO), a remote region from which samples were collected from air masses for which there were no large-scale up-wind continental aerosol sources. The TSIO samples can be divided into two populations: Population I aerosols, collected from air masses which have probably impinged on Madagascar, and Population II aerosols, which have been confined to open-ocean regions to the south of the area.The data indicate that there are strong latitudinal variations in the chemical signatures of aerosols over the Indian Ocean. The input of crustal material to the Arabian Sea gives rise to an average Al concentration of about 1000 ng m⁻³ of air in the northeast monsoon regime. As a result, the concentrations of all trace metals are relatively high, and the values of crustal enrichment factors are less than 10 for most metals, in the AS aerosols. In contrast, TSIO Population II ‘open-ocean southern air’ sampled during the southwest monsoon season, has an average Al concentration of only about 10 ng m⁻³ of air. Trace metal concentrations in the TSIO ‘open-ocean southern air’ during the southwest monsoon season are representative of ‘clean’ remote marine air and are generally similar to those reported over the central North Pacific.Mineral dust concentrations over the Indian Ocean decrease in a north to south direction, from about 15–20 μg m⁻³ of air in the extreme north to about 0.01–0.25 μg m⁻³ of air in the far south. The deposition of mineral dust over the northern Arabian Sea can account for approximately 75% of the non-carbonate material incorporated into the underlying sediments.In the Arabian Sea the dissolved atmospheric inputs of all the trace metals, with the exception of Cu and Co, exceed those from fluvial run-off by factors which range from 9.6 for Pb to 1.6 for Cr.