Janet O. Lamberson

Sediment toxicity to a marine infaunal amphipod: Cadmium and its interaction with sewage sludge

Abstract The acute toxicity of cadmium to the marine infaunal amphipod, Rhepoxynius abronius , was determined separately in sediment and seawater. Most cadmium added to test sediment was bound to particles and less than 5% was dissolved in interstitial water. The LC 50 based on cadmium concentration in interstitial water was similar to the LC 50 based on cadmium concentration in seawater without sediment. Cadmium in interstitial water, rather than that bound to particles, therefore appears responsible for acute sediment toxicity to this species. The addition of small quantities of sewage sludge or an increase in the proportion of the fine fraction of sediment particles significantly reduced the toxicity of cadmium in sediment. Binding of cadmium by sediment particles may explain the presence of phoxocephalid amphipods at sites where sewage and metal pollution occur together. The cadmium sensitivity of R. abronius is similar to that of several marine invertebrates commonly used in seawater bioassays. This amphipod is a useful test species for sediment bioassays used in research, monitoring and regulatory programs.

Sediment toxicity and the distribution of amphipods in Commencement bay, Washington, USA

Abstract The toxicity of 175 sediment samples from Commencement Bay, Washington, was measured by the survival of marine infaunal amphipods (Rhepoxynius abronius) during ten-day exposure to test sediment. Survival was high in sediment from offshore, deeper parts of the Bay, including two designated dredge material disposal sites. Within each of the major industrialized waterways there was a wide range in amphipod survival. Both acutely toxic and relatively nontoxic samples were collected from various areas within the Hylebos, Blair, Sitcum and City Waterways. Habitat differences, sedimentation rates, proximity to contaminant sources and sinks, and disruption of the seabed by prop scour and dredging could contribute to this variation in toxicity. Community structure data show a correlation between amphipod distribution and sediment toxicity, with lower amphipod density and species richness in the waterways than in the deeper part of the Bay. Phoxocephalid amphipods, a family that includes the bioassay species, were ubiquitous in the deeper Bay, but absent from the waterways. This correlation between laboratory and field results indicates the ecological relevance of the sediment bioassay.

Influences of sedimentary organic matter quality on the bioaccumulation of 4‐nonylphenol by estuarine amphipods

Nonylphenol (NP) is a moderately persistent, hydrophobic chemical with endocrine-disrupting and acute narcotic effects in aquatic biota. Concern exists about the ultimate fate of NP in aquatic ecosystems and the potential for bioaccumulation by benthic biota from the sediment with the potential for further transfer to higher trophic levels. Our goals were to determine if benthic amphipods bioaccumulate significant amounts of NP from sediment and to determine how additions of organic matter influence NP bioaccumulation by amphipods. Estuarine sediment was spiked with 14C-NP and enriched with two types of organic carbon (OC) sources of different nutritional qualities. Macrophytic algae (Ulva species) were used as a labile and nutritious OC source. Wood lignins were used as a refractory and low-nutrition OC source. Nonylphenol bioaccumulation was measured in Eohaustorius estuarius, Grandidierella japonica, and Corophium salmonis after 16 d of exposure. Nonylphenol accumulation was inversely proportional to OC quantity, but was unaffected by OC nutritional quality. Significant differences were found in the accumulation patterns between the three amphipod species. Mean biota-sediment accumulation factors ranged from 8.1 to 33.9 in E. estuarius, from 4.6 to 17.2 in G. japonica, and averaged 7.1 in male C. salmonis and 16.0 in female C. salmonis. These accumulation factors indicate that estuarine amphipods could constitute an important source of NP to higher trophic levels, such as juvenile fish.

Response of the phoxocephalid amphipod,Rhepoxynius abronius, to a small oil spill in Yaquina Bay, Oregon

A spill of approximately 284,000 liters of Bunker C and diesel fuel oils occurred at the entrance of Yaquina Bay, Oregon, following the wreck of the freighterBlue Magpie on 19 November 1983. A portion of this oil entered the lower estuary and was deposited on subtidal benthic habitats occupied by the phoxocephalid amphipodRhepoxynius abronius. This species is particularly sensitive to contaminants in sediment and its life history had previously been studied at the same sites affected by the spill. The oil was initially present as small, sand-coated globules at the study site, and persisted in association with detritus and sediment for months. Bioassays withRhepoxynius abronius showed that the oil globules were not acutely toxic unless mixed into the sediment at concentrations of 1.0 parts per thousand or greater. A series of 10-d bioassays before and after the spill showed that sediment collected from oiled subtidal sites did not become acutely toxic to this species. Although the density of theR. abronius population declined by 75% after the spill, similar declines of the same population were observed at this site in fall 1980. Oil-exposedR. abronius from Yaquina Bay were slightly more sensitive to cadmium in sediment than individuals from Whidbey Island, Puget Sound, Washington. Although mean fecundity was greater in 1984 than in 1981, recruitment following the spill was lower than in the 1980–1981 study. Thus, there is limited evidence for a small impact of the oil spill on this sensitive amphipod.

Intertidal habitat utilization patterns of birds in a Northeast Pacific estuary

A habitat-based framework is a practical method for developing models (or, ecological production functions, EPFs) to describe the spatial distribution of ecosystem services. To generate EPFs for Yaquina estuary, Oregon, USA, we compared bird use patterns among intertidal habitats. Visual censuses were used to quantify abundance of bird groups and general species richness in: Zostera marina (eelgrass), Upogebia (mud shrimp)/mudflat, Neotrypaea (ghost shrimp)/sandflat, Zostera japonica (Japanese eelgrass), and low marsh estuarine habitats. Also assessed were (1) spatial variation within a habitat along the estuary gradient and, (2) temporal variation based on bi-monthly samples over a year at five tidal ranges. Z. marina was an important estuarine habitat based on nearly all metrics of bird use, except for shorebird densities. This suggests that reductions in native eelgrass habitat may reduce the abundance and diversity of birds in Yaquina estuary. Our results suggest that a habitat based assessment approach is generally feasible for developing relative EPFs related to the presence of birds within estuarine systems.