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.

Effects of chlorpyrifos on field- and laboratory-developed estuarine benthic communities.

Macrobenthic animal communities, developed in sand-filled aquaria in the laboratory and in the field, were exposed to various concentrations of the insecticide chlorpyrifos, and effects on community structure were assessed. Laboratory communities were continuously exposed to the toxicant for 8 wk during colonization by planktonic larvae in unfiltered Santa Rosa Sound, Fla., seawater. Field communities were developed for 8 wk in aquaria placed in Santa Rosa Sound, then removed to the laboratory for exposure to chlorpyrifos for one week. Abundance of arthropods was significantly diminished (alpha = 0.05) by measured concentration of chlorpyrifos greater than or equal to 0.1 microgram/l in water in laboratory communities and by 5.9 microgram/l in water in field communities. Numbers of annelids and chordates in contaminated aquaria were not reduced by the highest concentrations of chlorpyrifos tested, 8.5 microgram/l in laboratory-colonized aquaria and 5.9 microgram/l in field-colonized aquaria. One species of annelid, Cistenides gouldii, was more abundant in field aquaria receiving 1.0 microgram/l or 5.9 microgram/l than in the control and lowest concentration. Molluscan larvae colonizing laboratory aquaria were sensitive to greater than or equal to 0.1 microgram/l; however, later developmental stages characterizing field aquaria were not sensitive to less than or equal to 5.9 microgram/l. Although only 20 of 78 animal species appeared in both laboratory and field communities, sensitivity of animals in these tests and in single species tests could be compared.

Effects of sevin on development of experimental estuarine communities.

The composition of animal communities developing from planktonic larvae in aquariums. A marked increase in the abundance of the annelid Polydora ligni in aquariums containing sand and flowing estuarine water was altered in the presence of the carbamate insecticide Sevin (carbaryl). Treatments were control and concentrations of Sevin that averaged 1.1, 11.1, and 103 micrograms/l; each treatment was replicated 8 times. Animals that colonized aquarium sand were collected in a 1-mm mesh sieve after 10 wk of exposure. Mollusks' arthropods, annelids, and nemerteans were the numerically dominant phyla. The average number of species per aquarium was significantly less (alpha = 0.05) in aquariums containing 11.1 or 103 micrograms/l than in those containing 1.1 micrograms/l or in control aquariums. The abundant clam Ensis minor grew significantly less in length at the higher concentrations of Sevin. The amphipod Corophium acherusicum was particularly affected; significantly fewer were found at all concentrations than in the control aquariums containing 103 micrograms/l corresponded to a marked decrease in the number of other annelids and to a significant absence of nemerteans.

Effects of pentachlorophenol on the development of estuarine communities.

Pentachlorophenol affected the composition of communities of estuarine organisms developed in sand from planktonic larvae in estuarine water that flowed through ten control aquaria and ten aquaria per exposure concentration averaging 7, 76, or 622 microgram/liter. Annelids, arthropods, and mollusks were the numerically dominant phyla when animals were collected in a 1-mm-mesh sieve after 9 wk of exposure. Mollusks were markedly fewer at 7 microgram/liter; annelids and arthropods at 76 microgram/liter. Almost no animals occurred at 622 microgram/liter. The total numbers of individuals and species were significantly less (alpha=0.01) in aquaria exposed to 76 microgram/liter than in those unexposed or exposed to 7 microgram/liter.

Effects of leached mirex on experimental communities of estuarine animals.

Experimental communities of various estuarine animals in outdoor tanks were exposed to a continuous flow of water containing mirex for 10 weeks. The mirex was leached from fire ant bait (0.3% active ingredient) by fresh water which was then mixed with salt water to yield exposure concentrations averaging 0.038 mug/L. The experiment simulated runoff from treated land into estuarine areas. Mortality of grass shrimp (Palaemonetes vulgaris), pin, shrimp (Penaeus duorarum), common mud crabs (Panopeus herbstii), and striped hermit crabs (Clibanarius vittatus) was significantly high in tanks containing the toxicant. Mortality of ribbed mussels (Modiolus demissus) and American oysters (Crassostrea virginica) was significantly lower in treated tanks, probably because numbers of both species of crabs, which ate the bivalves, were reduced. Sheepshead minnows (Cyprinodon variegatus) were least affected by mirex. Almost all deaths occurred after 10 or more days of exposure. All exposed animals accumulated mirex, with maximum concentrations ranging from 5,500X (pink shrimp) to 73,700X (soft tissues of oysters) above the concentration in the water. Sand substratum contained mirex up to 1,500X that in the water. The study demonstrated that mirex can be leached from bait by fresh water and concentrated by and affect survival of members in an experimental estuarine community.

Seasonal effects of leached mirex on selected estuarine animals.

Four 28-day seasonal experiments were conducted using selected estuarine animals in outdoor tanks that received continuous flow of mirex-laden water. Mirex (dodecachlorooctahydro-1,3,4-metheno-2H-cyclobuta [cd] pentalene) leached from fire ant bait (0.3% mirex) by fresh water and then mixed with salt water was toxic to blue crabs (Callinectes sapidus), pink shrimp (Penaeus duorarum), and grass shrimp (Palaemonetes pugio) but not to sheepshead minnows (Cyprinodon variegatus), at concentrations less than 0.53 mug/L in water. The amount of leaching was greatest in summer and least in spring. Greatest mortality occurred in summer at the highest water temperature and concentration of mirex; least mortality occurred in spring at the next to the lowest temperature and at the lowest concentration. Earliest deaths of blue crabs occurred after six days of exposure and shrimps after two days. Small juvenile crabs were more sensitive to leached mirex than were large juveniles. Mirex did not appear to affect growth or frequency of molting in crabs. All exposed animals concentrated mirex. Among animals that survived for 28 days, sheepshead minnows concentrated mirex 40,800X above the concentration in the water, blue crabs 2,300X, pink shrimp 10,000X, and grass shrimp 10,800X. Sand substrata contained mirex up to 770X that in the water. Most control and exposed animals in samples examined histologically had normal tissues, but alteration in gills of some exposed fish and natural pathogens in some exposed and control crabs and shrimp were observed. The experiments demonstrated that mirex can be leached from bait by fresh water, concentrated by estuarine organisms, and can be toxic to crabs and shrimps.