Rhepoxynius Abronius Research Articles

Effects of culture conditions on the sensitivity of a phoxocephalid amphipod, rhepoxynius abronius, to cadmium in sediment

AbstractExperiments were conducted to determine (a) the feasibility of maintaining laboratory cultures of the infaunal phoxocephalid amphipod Rhepoxynius abronius (Barnard), (b) the relative sensitivities of cultured versus freshly collected adult animals, (c) the sensitivities of adult versus juvenile R. abronius to cadmium in sediment and (d) the effect of handling on cultured amphipods. R. abronius held in sediment in a flow‒through seawater system for various lengths of time showed high survival, growth and sexual maturation for periods of up to 180 d. Cultured amphipods appeared normal and survived well (93%) under control toxicity test conditions, but were more sensitive to cadmium in sediment (LC50 = 4.4) than were freshly collected amphipods (LC50 = 8.7). Differences in cadmium LC50s between size classes (LC50 = 8.2 for juveniles and 11.5 for adults) were statistically significant, but not substantial. We recommend that large juveniles and adults (3 to 5 mm) be used in sediment toxicity tests because they are available from natural populations throughout the year, and that amphipods be collected within 14 d of use in sediment toxicity tests to minimize the interaction between culture and contaminant stresses.

Effects of mixtures of sediment contaminants on the marine infaunal amphipod, rhepoxynius abronius

AbstractThe infaunal amphipod, Rhepoxynius abronius Barnard, was exposed to mixtures of sediment contaminants at concentrations of the individual compounds that produce few or no effects. Combinations of zinc, mercury, polychlorinated biphenyls (Aroclor® 1254) and fluoranthene produced joint toxicological actions that could be classified as additive or less than additive. To be more ecologically relevant, sediment quality criteria should be expressed in relation to a model of interactive effects. A relatively small decrease in the total volatile solids content of sediment from 1.72 to 1.30% increased the concentration of contaminants in interstitial water and increased sediment toxicity.

Effects of natural sediment features on survival of the phoxocephalid amphipod, Rhepoxynius abronius

Effects of sediment particle size and water content on the survival of the amphipod, Rhepoxynius abronius, were examined by manipulating these natural sediment features within static laboratory microcosms. Mean amphipod survival in fine, uncontaminated, field sediments (≥ 80% silt-clay) can be 15% lower than survival in native sediment. Storage of sediments at 4°C over 7–14 days did not change sediment toxicity, but handling (i.e. elutriation and recombination) of muddy sediments increased toxicity. Sediment particle size and organic content had greater impact on the survival of R. abronius than did sediment water content in modifying amphipod survival, but we could not independently separate the effects of these two sediment variables. A new set of criteria is proposed to interpret toxicity results from the amphipod bioassay in the light of the mortality associated with fine sediment particle size. The efficacy of these criteria to separate mortality caused by fine particles and chemical contaminants was tested by analyzing field survey data from 78 Puget Sound (WA) Urban sites. Using our new criteria, the toxicity of these sediments was found to closely reflect the degree of chemical contamination. We propose that an approach similar to this be undertaken for toxicity tests whenever natural environmental factors induce mortality above background levels.

Toxicity of marine sediments supplemented with mixtures of selected chlorinated and aromatic hydrocarbons to the infaunal amphipod Rhepoxynius abronius

The toxicity of a reference sediment supplemented with mixtures of seven aromatic hydrocarbons (fluoranthene, phenanthrene, benz[a]anthracene, benzo[a]pyrene (BaP), 2,6-dimethylnaphthalene (DMN), 1-methylnaphthalene, and 2-methylnaphthalene, or four chlorinated hydrocarbons (polychlorinated biphenyls (PCBs, Aroclor 1254), hexachlorobutadiene, 2,2-bis( p-chlorophenyl)-1,1,1-trichloroethane and hexachlorobenzene) was evaluated in amphipod ( Rhepoxynius abronius) lethality bioassays. Significant mortality occurred among amphipods exposed for 10 days to a reference sediment (46% fines, 0·9% total organic carbon) supplemented with a mixture of chlorinated hydrocarbons at concentrations (0·05–1·0 μg g −1 dry wt) approximating those measured in contaminated sediments of Puget Sound, WA, as well as at concentrations five times as great (5 ×). In contrast, sediments supplemented with the aromatic hydrocarbon mixture were toxic only at the higher (5 ×) concentrations (0·5–15·0 μg g −1 dry wt). Sediment concentrations of the mixture components and their bioavailability to amphipods were assessed using radiolabeled PCBs, DMN and BaP. Measurement of radioactivity incorporated by R. abronius after the 10-day exposure period indicated a dose-related uptake of xenobiotic compounds from both the chlorinated and aromatic hydrocarbon-supplemented sediments. Dimethylnaphthalene and the metabolically refractive PCBs were bioaccumulated to a greater extent than BaP, which is known to be metabolized extensively by R. abronius.

Acute toxicity of interstitial and particle-bound cadmium to a marine infaunal amphipod

The relative acute toxicity of particle-bound and dissolved interstitial cadmium was investigated using a new bioassay procedure. Interstitial concentration of Cd was controlled by means of peristaltic pumps, allowing separate manipulation of interstitial and particle properties. Addition of small quantities of organic-rich fine particles to sandy sediment resulted in greatly differing particle-bound Cd concentrations in sediment with similar interstitial Cd concentrations. Analysis of variance indicated no significant difference in the survival or ability to rebury in sediment of the phoxocephalid amphipod Rhepoxynius abronius (Barnard), when exposed to sediment with different total Cd concentrations but nearly equal interstitial Cd concentrations; in one case LC 50 data indicated slightly increased mortality in sediment with higher total Cd concentration. At least 70·2–87·9% of mortality could be predicted from past data on mortality based on dissolved Cd concentrations. The acute toxicity of Cd to this infaunal amphipod appears to be due principally to Cd dissolved in interstitial water. Our results indicate that static and flow-through bioassay tests of this organism produce comparable results with regard to mortality and survival, while the flow-through system provides a greater capacity to manipulate experimental conditions.

Response of the phoxocephalid amphipod, Rhepoxynius abronius, to a small oil spill in Yaquina Bay, Oregon : Kemp, P.F., R.C. Swartz and J.O. Lamberson, 1986 Estuaries, 9(4B):340–347 Univ. of Georgia Mar. Inst., Sapelo Island, GA 31327, USA

Response of the phoxocephalid amphipod, Rhepoxynius abronius, to a small oil spill in Yaquina Bay, Oregon : Kemp, P.F., R.C. Swartz and J.O. Lamberson, 1986 Estuaries, 9(4B):340–347 Univ. of Georgia Mar. Inst., Sapelo Island, GA 31327, USA

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.

Experimental analysis of density dependent emigration of the amphipodRhepoxynius abronius

Laboratory experiments tested the short‐term, sex specific emigration response of the infaunal amphipod Rhepoxynius abronius (Barnard) to intraspecific density. Emigration of amphipods from the sediment into the water column increased monotonically with greater test densities. A significantly higher percentage of amphipods emigrated at a density equivalent to 16,000 m2 than at a density of 4,000 m2. No significant difference in the emigration behaviour of males and females was detected. These results suggest that there is a strong selective advantage for R. abronius to avoid high densities of potential competitors and offer one explanation for the occurrence of these amphipods and perhaps other infauna in the water column.

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

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.

Acute toxicity of mine tailings to four marine species

Acute toxicity bioassays were conducted on mine tailings produced by pilot plant testing for the proposed Quartz Hill molybdenum mine, which will be situated near Ketchikan, Alaska. Tailings bioassays were conducted in seawater with juvenile coho salmon ( Oncorhynchus kisutch), mussel larvae ( Mytilus edulis), infaunal amphipods ( Rhepoxynius abronius), and euphausiids ( Euphausia pacifica). The same general range of mine tailings concentrations was acutely toxic to all four test species with acute effects observed between 61 000 to 277 000 mg l −1 (wet wt) tailings solids (range of 95% confidence limits for LC 50 and EC 50 values). Chemical analyses of bioassay test solutions and leaching test solutions were conducted for metals (including Cd, Cu, Pb, Zn, Mn and Mo), EPA Priority Pollutant base/neutral organics, and more general parameters such as sulphate, nitrate/nitrite, cyanides, phosphate and ammonia. Parameters possibly contributing to the observed toxicity were complex contaminant mixtures including total suspended solids and heavy metals. The present study provides information related to the marine disposal of mine tailings and shows that these mine tailings present a relatively low level of acutely toxic effects.

Life History and Productivity of the Phoxocephalid Amphipod Rhepoxynius Abronius (Barnard)

Rhepoxynius abronius (Barnard) (Amphipoda: Phoxocephalidae) is a predominantly subtidal species of the North American Pacific coast. It is also found sub- and intertidally within the polyhaline region of estuaries of Oregon and Washington. Within the Yaquina Bay estuary, Oregon, R. abronius is an annual species producing one or two broods per year. Recruitment occurs over an extended period from mid to late winter through summer. Mortality was 20-25% per month during mid to late spring through fall, and was low in winter through early spring. Mortality may be largely due to predation. Mortality of males appears higher than that of females during the reproductive season. The annual range in biomass was 40– 180 mg ash-free dry weight (AFDW)/0.5 m2, averaging 104 mg AFDW/0.5 m2. Secondary production was 160-216 mg AFDW/0.5 m2/yr and the annual ratio of production to mean biomass was 1.54-2.08. Production and the production: biomass ratio are similar to values reported for other marine amphipods with one or fewer generations per year.

Exposure of two species of deposit-feeding amphipods to sediment-associated [ 3H]benzo[ a]pyrene: Uptake, metabolism and covalent binding to tissue macromolecules

Two species of deposit-feeding marine gammaridian amphipods, Rhepoxynius abronius and Eohaustorius washingtonianus, were exposed to sediment-associated [ 3H]benzo[ a]pyrene (B aP) at 12±1°C. Concentrations of B aP-derived radioactivity increased with time in both E. washingtonianus and R. abronius, and the levels of radioactivity were similar in both species after 7 days of exposure. A significantly ( P<0.05) lower proportion (51%) of unconverted B aP was present in R. abronius than in E. washingtonianus (73%) at 1 day. The proportion of unconverted B aP decreased with time in R. abronius (30% at 7 days), but did not vary significantly with time in E. washingtonianus. Reverse-phase high-pressure liquid chromatography (HPLC) of organic solvent-soluble metabolites released from β-glucuronidase and arylsulfatase treated tissue extracts of amphipods showed the presence of metabolites such as 7,8-dihydroxy-7,8-dihydroB aP (B aP-7,8-diol), 9,10-dihydro-9,10-dihydroxyB aP (B aP-9,10-diol), 3-hydroxyB aP and 9-hydroxyB aP. The ratio of B aP-7,8-diol to B aP-9,10-diol obtained from normal-phase HPLC was 1.2 for R. abronius and 0.7 for E. washingtonianus. Moreover, the level of covalent binding of B aP intermediates to macromolecules was significantly ( P≤0.01) higher at 7 days in R. abronius (7.00±0.98 pmol B aP equivalents/g-protein) than in E. washingtonianus (4.08±0.51 pmol/g-protein). Thus, using B aP as a representative of sediment-associated polynuclear aromatic hydrocarbons, it was shown that although both amphipod species accumulated similar concentrations of BaP-derived radioactivity, R. abronius converted a higher proportion of B aP into potentially toxic intermediates.

Increased emigration of the amphipod Rhepoxyniusabronius (Barnard) and the polychaete Nephtys caeca (Fabricius) in the presence of invertebrate predators

Laboratory experiments tested whether the emigration of two infaunal organisms, the amphipod Rhepoxynius abronius (Barnard) and the polychaete Nephtys caeca (Fabricius) increased in the presence of potential predators. Significantly more Rhepoxynius abronius migrated into the water column in the presence of an epibenthic predator, the dungeness crab Cancer magister Dana, and two infaunal predatory polychaetes Glycera convoluta Keferstein and Nephtys caeca, than in their absence. Emigration of small N. caeca was greater in the presence of Glycera convoluta than in the presence of large Nephtys caeca or in the control. These results demonstrate that avoidance of predators may sometimes explain the occurrence of benthic organisms in the water column and indicate that reductions of infauna by predators in predator inclusion experiments may be due to prey emigration as well as direct predation.

Toxicity of sewage sludge toRhepoxynius abronius, a marine benthic amphipod

Relative toxicity of sewage sludges from six treatment plants was determined by the LC50 of sludge-sediment mixtures to the infaunal marine amphipod,Rhepoxynius abronius. LC50s were measured as the increase in the percent total volatile solids (TVS) of the mixture due to the addition of sludge required to kill 50% of the amphipods during a 10-day exposure. LC50s ranged from 2.83% TVS addition for sludge from the small, domestic community of Waldport, Oregon to <0.1% TVS addition for metropolitan, more industrialized sources in Los Angeles, California. The toxicity of the sludge-sediment mixtures is attributed primarily to chemical contamination rather than organic enrichment. Rank correlations between toxicity and specific chemicals were usually not statistically significant, indicating that different combinations of stresses involving multiple or unmeasured factors were probably responsible for observed effects. Integrative measures of contamination (oil/grease concentration; consensus ranking of contamination based on 15 parameters) were significantly correlated withR. abronius survival indicating that the more toxic sludges had a higher overall level of contamination.

EDTA chelation and zinc antagonism with cadmium in sediment: effects on the behavior and mortality of two infaunal amphipods

The two species of infaunal amphipod crustaceans Rhepoxynius abronius (Phoxocephalidae) and Eohaustorius sencillus (Haustoriidae) are characteristic of nearshore sandy bottoms along the California (USA) coast, and are highly sensitive to moderate levels of heavy metals. In laboratory experiments, both zinc and the chelator EDTA increased the survival of amphipods in sediment containing otherwise lethal levels of cadmium (8.5 μg g-1), which are representative of moderately polluted environments. In simple choice experiments, amphipods prefer sediment with complexed cadmium. The behavioral and survival patterns of both species were similar in the experiments. EDTA prevented about 50% of the added cadmium from initially being incorporated into the sediment, and increased the rate of cadmium released from the sediment. These data illustrate the limitations of operational definitions of chemical analyses, since weak-acid (0.5 N HCl) leaches that were intended to provide an estimate of the “biologically available” metal concentrations extracted both toxic and EDTA-complexed cadmium species and did not account for their antagonistic interctions with zinc.

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.