Howard M. Feder

A Regional Multiple-Stressor Rank-Based Ecological Risk Assessment for the Fjord of Port Valdez, Alaska

We conducted an ecological risk assessment of the marine environment of Port Valdez, a fjord in south-central Alaska. Because the assessment was regional rather than site-specific and contained a large number of different stressors in a variety of environments, we required a nontraditional method to estimate risks. We created a Relative Risk Model to rank and sum individual risks numerically within each subarea, from each source, and to each habitat. Application of this model involved division of Port Valdez into 11 subareas containing specific ecological and anthropogenic structures and activities. Within each subarea, the stressor sources were analyzed to estimate exposure of receptors within habitats leading to effects relevant to the chosen assessment endpoints. The subareas were analyzed and compared to form a Port-wide perspective of ecological risk. Available chemical concentrations from sediment and mussels collected from the Port were compared to various toxicological benchmarks as a partial conf...

Towards a pan-Arctic inventory of the species diversity of the macro- and megabenthic fauna of the Arctic shelf seas

Although knowledge of Arctic seas has increased tremendously in the past decade, benthic diversity was investigated at regional scales only, and no attempt had been made to examine it across the entire Arctic. We present a first pan-Arctic account of the species diversity of the macro- and megabenthic fauna of the Arctic marginal shelf seas. It is based on an analysis of 25 published and unpublished species-level data sets, together encompassing 14 of the 19 marine Arctic shelf ecoregions and comprising a total of 2,636 species, including 847 Arthropoda, 668 Annelida, 392 Mollusca, 228 Echinodermata, and 501 species of other phyla. For the four major phyla, we also analyze the differences in faunal composition and diversity among the ecoregions. Furthermore, we compute gross estimates of the expected species numbers of these phyla on a regional scale. Extrapolated to the entire fauna and study area, we arrive at the conservative estimate that 3,900–4,700 macro- and megabenthic species can be expected to occur on the Arctic shelves. These numbers are smaller than analogous estimates for the Antarctic shelf but the difference is on the order of about two and thus less pronounced than previously assumed. On a global scale, the Arctic shelves are characterized by intermediate macro- and megabenthic species numbers. Our preliminary pan-Arctic inventory provides an urgently needed assessment of current diversity patterns that can be used by future investigations for evaluating the effects of climate change and anthropogenic activities in the Arctic.

Growth and predation by the ochre sea star, Pisaster ochraceus (Brandt), in Monterey Bay, California

Abstract The growth rate of one laboratory and three field populations of the rocky intertidal sea star Pisasfer ochraceus from Monterey Bay, California, is considered. Both arm-length and weight were used to assess growth, but the latter measurement proved a more reliable one. The mean monthly increase in size for laboratory sea stars (on an unrestricted diet of Mytilus calijornianus) weighing less than 50 grams was 34.4 % while those weighing 800-1200 grams increased 7.1 %. Laboratory controls starved for 18 months lost 35.2 % of their body weight. Sea stars in the field (on a restricted diet both qualitatively and quantitatively) grew much more slowly than laboratory individuals. Most gained weight during the year, but much of this was associated with gonad development. Some sea stars in the field showed a net loss in weight during the year after spawning. The mean size of sea stars living primarily on mussels in the field was greater than that of animals living on acorn barnacles. The relationship bet...

Food and feeding habits of the king crab Paralithodes camtschatica near Kodiak Island, Alaska

Stomach contents from 809 king crabs, Paralithodes camtschatica (Tilesius), from 6 areas near Kodiak Island, Alaska, and 9 sampling periods (1978–1979) were exammed quantitatively; 713 (88%) contained food. Mollusca (mainly the bivalves Nuculana spp., Nucula tenuis, and Macoma spp.) and Crustacea (mainly barnacles) were the dominant food groups in terms of percentage wet weight and frequency of occurrence; fishes were the next most important group of prey. No significant differences in feeding between sexes occurred; however, significant differences were apparent in the quantity of food consumed from different sampling periods, areas, depths, size groups, and crab molt-classes. Consumption was greater in spring and summer and in offshore locations at depths of 126 to 150 m. In addition, king crabs <140 mm carapace length (CL) consumed more food than crabs ≧140 mm CL. Adult, newshell (individuals that molted during the last molting period) females greater than 95 mm CL, and newshell males greater than 100 mm CL, each contained more food than did juvenile, newshell females <120 mm CL.

Southeastern Chukchi Sea (Alaska) macrobenthos

Macrobenthos in the southeastern Chukchi Sea, inclusive of the Chukchi Bight and Kotzebue Sound, were collected in 1985–1987 to determine factors influencing faunal distribution, abundance and biomass. Polychaetes, crustaceans, bivalve mollusks, and ophiuroid echinoderms dominated abundance. Polychaetes, bivalve mollusks, and ophiuroid echinoderms dominated carbon biomass with barnacles, amphipods, bryozoans, and tunicates occasionally dominant. Cluster analysis and ordination revealed relatively high faunal abundance and biomass under Bering Shelf Anadyr Water (BSAW) as well as under Alaska Coastal Water (ACW) in the Bight and Sound. Advected particulate carbon from the highly productive BSAW supported the abundant macrobenthos that served as food for numerous epifauna, which in turn furnished food for resident and transient populations of demersal fishes and marine mammals.

The deep benthos of Prince William Sound, Alaska, 16 months after the Exxon Valdez oil spill

Abstract In 1990, 16 months after the T/V Exxon Valdez oil spill (EVOS) in Prince William Sound, Alaska, an assessment of the benthic macrofauna and associated environmental parameters at 40 and 100 m was made. Assessment of the biota and environmental data demonstrated patterns in deep benthic assemblages reflective of oceanographic conditions, as indicated by sediment differences, rather than EVOS toxicity. Comparison of polynuclear aromatic hydrocarbons (PAH) and δ13C values in sediments between stations within the oil trajectory and reference stations outside of the trajectory showed no significant differences. This investigation uncovered no signals of disturbance 16 months after the EVOS. These results agree with conclusions of studies of intertidal and shallow subtidal regions following the EVOS that demonstrated disturbance effects decreasing with depth.

Aspects of the feeding biology of the brittle star Ophiura texturata

Abstract Ophiura texturata was examined for its food habits at Ellekildehage in the Oresund and the Isefjord, Denmark. Food occurred in 51 % of the O. texturata examined from the Oresund and 55 % of the brittle stars from the Isefjord. The ophiurid ingests at least 41 small epifaunal and infaunal taxa, a variety of miscellaneous items, and sediment. Food analyses suggest that O. texturata is a potential predator of meiofauna, recently settled larvae, and small benthic macrofauna. In both areas, O. texturata utilized common, accessible prey items. In the Isefjord, where recently settled bivalve mollusks were numerous, the ophiurid fed intensively on them. Polychaetous annelids were also important in the latter area. Echinoderms, (primarily ophiurids), small crustaceans, and mollusks (gastropods, bivalves), in decreasing order of importance, were taken in the Oresund. The suggestion that omnivorous species such as O. texturata may be more destructive to newly settled young than are specialized predators, e....

Assessment of the benthic environment following offshore placer gold mining in the northeastern Bering Sea

Abstract The effects of offshore placer gold mining on benthic invertebrates were assessed on ‘sand’ and ‘cobble’ substrates in Norton Sound, northeastern Bering Sea. Mining with a bucket-line dredge occurred nearshore in 9–20 m during June to November 1986–90. Sampling nearly a year subsequent to mining demonstrated minor alteration of substrate granulometry with no clear trends. However, benthic macrofaunal community parameters (total abundance, biomass, diversity) and abundance of dominant families were significantly reduced at mined stations. Many of the dominant taxa are known prey of the locally important red king crab (Paralithodes camtschaticus). Dominance of opportunistic species and small sizes at unmined and mined sites represents faunal responses to the natural dynamics of the region where establishment of populations of large, sexually-mature individuals is typically precluded. Multi-year bathymetric surveys of an area only mined in 1986 showed a continued smoothing of ocean bottom relief, decreasing size of tailing footprint, and shoaling of depressions left by mining. An ordination (multidimensional scaling) of taxon abundance data from mined (1 year after mining), recolonizing (2–7 years after mining) and unmined stations shows configurations that reflect disturbance. Recovery of the biota was underway in both substrates after 4 years, but this process was interrupted in the fall of the fourth year (1990) by several severe storms. Mining effects are contrasted with local natural disturbances.

Benthic food web structure in the southeastern Chukchi Sea: an assessment using δ13C and δ15N analyses

The benthos of the southeastern Chukchi Sea shelf is typified by high faunal abundance and biomass resulting from settlement of a large proportion of seasonal phytoplankton under highly nutritious offshore Bering Shelf Anadyr Water (BSAW). In contrast, inshore Alaska Coastal Water (ACW) is much less productive. Yet the Chukchi Bight and Kotzebue Sound, located under ACW in the southeastern Chukchi Sea, contain a substantial faunal abundance and biomass of invertebrates, fishes and marine mammals. We examined food web structure to gain an understanding of how a relatively rich benthic fauna with a high biomass can be supported under ACW with a supposedly low flux of carbon to the benthos. We measured stable isotope (δ13C and δ15N) values of selected organisms (from zooplankton to fishes) as markers of food sources and trophic position to compare fauna on the shelf under BSAW with that in the Chukchi Bight and Kotzebue Sound under ACW. Relative isotope position of organisms in all three regions was similar, even though some pelagic species within the Sound were depleted in δ13C compared to the other regions. We attribute the depletion to the influence of terrestrially derived carbon. We suggest that the hydrodynamics along an oceanic front between the Chukchi Shelf and the Chukchi Bight support the advection of nutrient-rich POC into the Bight and Sound as additional food sources to local production. We conclude that local conditions and multiple POC sources in the Bight and Sound support the substantial population of benthic invertebrates and the fishes, seabirds, and marine mammals that feed on them.

Adjustment of benthic fauna following sediment disposal at a site with multiple stressors in Port Valdez, Alaska.

The shallow subtidal macrobenthos at Port Valdez, Alaska, was examined to assess faunal adjustment following disposal of dredged sediments over a three-year period. Prior to sediment disposal, the infauna consisted of a relatively species-rich assemblage dominated by sessile polychaetes and bivalves. Six months after disposal, virtually all taxa present prior to dredging and disposal were rare or absent with opportunistic taxa dominant. Surveys performed 1.5 years after sediment disposal indicated faunal adjustment was in progress; large, sessile polychaetes and bivalves were still present in low numbers after 2.5 years. At one station, increasing organic enrichment by fish-wastes from adjacent processing plants resulted in a shift to a highly disturbed benthic assemblage. The trends in the faunal assemblage suggest that environmental conditions were still in a state of flux 2.5 years after the dredging event.