Christine H. Deans

Effects of organotins on growth and survival of two marine diatoms, Skeletonema costatum and Thalassiosira pseudonana

Abstract Tributyl- and triphenyltin compounds inhibited population growth and cell survival of marine unicellular algae at low concentrations. They may pose a threat to algae in areas of industrial outfalls and heavy boat traffic.

Inhibition of arm regeneration by Ophioderma brevispina (Echinodermata, Ophiuroidea) by tributyltin oxide and triphenyltin oxide

Effects of water-bourne toxicants on regeneration of arms by the brittle star, Ophioderma brevispina, are described. Regeneration was inhibited by 0.1 micrograms liter-1 bis(tri-n-butyltin)oxide and bis(triphenyltin)oxide. Both substances are known to act upon the nervous system, and it is suggested that inhibition was caused by neurotoxicological action of the tin compounds or by their direct effect upon tissue at the breakage point. The former is most likely because regeneration is mediated by the radial nerves of brittle stars.

Alterations in composition of field- and laboratory-developed estuarine benthic communities exposed to di-n-butyl phthalate☆

Abstract Macrobenthic animal communities developed in sand-filled aquaria in the laboratory and in the field were exposed to three concentrations of the plasticizer, di-n-butyl phthalate (DBP), and effects on community structure were assessed. Laboratory communities were colonized by planktonic larvae in unfiltered sea water; field communities, by naturally occurring animals. After 8 wk of colonization, laboratory and field communities (removed to the laboratory) were exposed to DBP for 2 wk. The numbers of individuals and species of animals in aquaria receiving 3.7 mg DBP/l (laboratory-colonized) or 3.8 mg DBP/l (field-colonized) were significantly less than those in control aquaria or in aquaria that received lower concentrations of the plasticizer. Affected phyla in laboratory or field faunal assemblages were chordates, mollusks, arthropods, and annelids. Amphipods, Corophium acherusicum, collected only from laboratory communities, also were significantly fewer in communities exposed to 0.34 mg DBP/l. Density of individuals and numbers of species were not affected by 0.04 mg DBP/l.

Effects of 1,2,4-trichlorobenzene on estuarine macrobenthic communities exposed via water and sediment

Macrobenthic animal communities that colonized sand-filled aquaria were exposed to 1,2,4-trichlorobenzene (TCB), a recent replacement for polycholorinated biphenyls in the electrical industry. In one test, communities established by planktonic larvae entrained in continuously supplied unfiltered seawater for 50 days were exposed to waterborne TCB for 6 days; in the second test, the toxicant was added to the sediment before 8 weeks of colonization. Concentrations that affected community structure were usually two orders of magnitude lower for waterborne TCB than for sediment-bound TCB, but the same types of organisms were affected by each route of exposure. The lowest TCB concentrations (measured) that affected average numbers of individuals exposed via the water were 0.04 mg/liter for mollusks, 0.4 mg/liter for arthropods, and 4 mg/liter for annelids. Average number of species was significantly lower than the control at 4 mg/liter. For TCB exposures via the sediment, the lowest concentrations (nominal) that affected average numbers of individuals were 100 micrograms/g for mollusks and echinoderms, and 1000 micrograms/g for arthropods and annelids. Average number of species in experimental aquaria was significantly lower than the control at greater than or equal to 100 micrograms/g. TCB persisted in sediments, but some leached into water throughout the 8-week exposure via sediment.

Comparison of field- and laboratory-developed estuarine benthic communities for toxicant-exposure studies

The structures of macrobenthic communities that colonized sand-filled boxes in laboratory and field were compared to learn if laboratory-developed assemblages of animals used in toxicity studies realistically simulate those in nature. Laboratory boxes were colonized for eight weeks in the Spring and Fall by planktonic larvae from continuously-supplied unfiltered seawater; field boxes, by naturally-occurring estuarine animals. Laboratory communities had larger numbers, but fewer species than field communities. One-fourth of the species found in field boxes also occured in laboratory boxes. Species density, diversity, and dominance were similar in both environments in the Fall, but differed in the Spring. The degree of similarity of laboratory assemblages of benthic animals to the highly variable assemblages in the field indicates applicability of laboratory toxicity studies to nature.

Responses of macrobenthos colonizing estuarine sediments contaminated with drilling mud containing diesel oil

Acute toxicities and sublethal effects were determined in several investigations for 11 types of drilling muds obtained from offshore drilling sites in the Gulf of Mexico, which the Petroleum Equipment Suppliers Association supplied to the Environmental Protection Agency. All were used muds that had been recycled during drilling. Those containing the highest amounts of No. 2 diesel fuel oil were the most acutely toxic to mysids (Mysidopsis bahia), grass shrimp (Palaemonetes pugio), quahog clams (Mercenaria mercenaria), and sand dollars (Echinarachnius parma) and elicited the greatest sublethal responses in corals (Acropora cervicornis). A lignosulfonate mud was the most toxic, followed by a lime mud containing 3.98 mg diesel/g. The present study was initiated to determine the impact of the lime mud with its diesel oil component on field colonization by macrobenthos.