Douglas P. Middaugh

Relative sensitivity of six estuarine fishes to carbophenothion, chlorpyrifos, and fenvalerate.

The acute toxicity (96-hr LC50) of carbophenothion, chlorpyrifos, and fenvalerate to six estuarine fishes was determined in flow-through laboratory tests. The atherinid fishes (Menidia menidia, M. peninsulae, M. beryllina, and Leuresthes tenuis) consistently were among the most sensitive species tested and were similar to each other in their sensitivity to pesticides. The sensitivity of sheepshead minnows (Cyprinodon variegatus) to carbophenothion was the same as that of the atherinids. For fenvalerate, the sheepshead minnow LC50 was an order of magnitude greater than that of the most sensitive atherinid, whereas the LC50 for chlorpyrifos and sheepshead minnows was two orders of magnitude greater. Gulf toadfish (Opsanus beta) were the least sensitive fish tested with carbophenothion and chlorpyrifos and their 96-hr LC50 for fenvalerate ranked between the LC50 for sheepshead minnows and atherinids. Test results were compared to acute toxicity data for other estuarine fishes and invertebrates.

Responses of early life history stages of the striped bass,Morone saxatilis to chlorination

The toxicity of total residual chlorination (TRC) to early life stages of the striped bass,Morone saxatilis, was determined using percent embryo hatchability, incipient LC50 bioassays, histopathology, and avoidance responses.

Reproductive ecology of the inland silverside, Menidia beryllina, (Pisces: Atherinidae) from Blackwater Bay, Florida

WHITMORE, C. P., AND P. H. DUTTON. 1985. Infertility, embryonic mortality and nest-site selection in leatherback and green sea turtles in Suriname. Biol. Conserv. 34:251-272. WITZELL, W. N. 1983. Synopsis of biological data on the hawksbill turtle, Eretmochelys imbricata (Linnaeus, 1766). FAO Fisheries Synopsis 137:1-78. ZAR, J. H. 1984. Biostatistical analysis, 2d ed. Prentice-Hall, Englewood Cliffs, New Jersey. (KAB) CENTER FOR SEA TURTLE RESEARCH AND DEPARTMENT OF ZOOLOGY, UNIVERSITY OF FLORIDA, GAINESVILLE, FLORIDA 32611, AND (ABB) CENTER FOR SEA TURTLE RESEARCH AND DEPARTMENT OF WILDLIFE AND RANGE SCIENCES, UNIVERSITY OF FLORIDA, GAINESVILLE, FLORIDA 32611. Accepted 13 Dec. 1990.

Responses of embryonic and larval inland silversides, Menidia beryllina, to a water-soluble fraction formed during biodegradation of artificially weathered Alaska North Slope crude oil

Weathered Alaska North Slope crude oil (ANS 521) was stirred for 2 and 14 days in 20‰ salinity sterile seawater or for 14 days in seawater with nutrients and a group of three (GO3) microorganisms from Prince William Sound, Alaska, that were capable of biodegrading hydrocarbons. A total of 0.65 and 0.69 mg/L water soluble fraction (WSF) of neutral fraction hydrocarbons was recovered from the 2- and 14-day stirred sterile systems, respectively. In comparison, a total of 7.5 mg/L WSF neutral fraction hydrocarbons was recovered from systems containing ANS 521 that were stirred and biodegraded by the GO3 microbes for 14 days. Toxicity/teratogenicity tests were conducted with neutral fraction hydrocarbons recovered from the sterile and biodegraded systems using embryonic inland silversides, Menidia beryllina. Hydrocarbons from the sterile systems did not cause statistically significant teratogenic responses at concentrations of 1%, 10%, and 100% (w/v) of recovered fractions (redissolved in 20‰ salinity sterile seawater). Counts of heart contraction rates were significantly lower (α≤0.05) at the 100% WSF concentration of hydrocarbons on days 5 and 6 of embryogenesis. In contrast, recovered and redissolved neutral fraction hydrocarbons from ANS 521, that were biodegraded for 14 days, caused statistically significant (α≤0.05) teratogenic responses at the 1, 10, and 100% WSF concentrations. Measurement of heart contraction rates showed statistically significant (α≤0.05) reductions at the 100% WSF concentration on days 2 through 6 of embryogenesis, compared to controls.

Reproductive behavior of the Atlantic silverside, Menidia menidia (Pisces, Atherinidae)

SynopsisThe spawning behavior of the Atlantic silverside,Menidia menidia, was studied at two sites on the North Edisto River estuary in South Carolina. Prespawning schools moved back and forth along the shoreline as the time of high tide approached. Spawning runs took place in the upper intertidal zone at high tide.Spawning fish deposited their eggs on three types of substrates: 1) the lower stems of cordgrass plants,Spartina alterniflora, 2) detrital mats, and 3) exposed cordgrass roots along erosional scraps. Spawning behavior during egg deposition and fertilization was similar for all three substrates. Females released eggs during a rapid fluttering motion of the posterior half of the body. A similar movement accompanied release of sperm by males. Behavior of fish just prior to spawning insured deposition of gametes at locations that provided protection from thermal and drying stress during development. Eggs were deposited at mean intertidal elevations of 1.8 and 1.5 meters above mean low water (MLW) at respective study sites. They were exposed to the atmosphere for approximately ten hours between successive high tides.During spawning runs in which eggs were deposited at the base of cordgrass plants, ambient dissolved oxygen concentrations of the water in the spawning area were sometimes reduced to < 1.0 mg. 1−1. Spent fish, apparently incurring an oxygen debt while spawning, formed a nonschooling aggregation offshore from the spawning zone.The recurrent use of specific spawning substrates for egg deposition resulted in an uneven distribution of spawning runs along the shoreline at each study site.

Detoxification of pentachlorophenol and creosote contaminated groundwater by physical extraction: Chemical and biological assessment

Chemical analyses revealed that polycyclic aromatic hydrocarbons (PAHs) and other organic compounds were present in a perennial freshwater stream that flowed through the abandoned American Creosote Works and into Pensacola Bay, Florida. Moreover, groundwater pumped from a well depth of 21 m at a location adjacent to the site was heavily contaminated with PAHs and other organics.A study was conducted to determine the efficacy of ultrafiltration for removal of organics from groundwater at this U.S. Environmental Protection Agency, Super Fund site. Ultrafiltration reduced the concentration of total identified organics from 210.0 mg/L in groundwater to 1.5 mg/L in the post-filtration permeate.Tests for toxicity/teratogenicity in embryonic inland silversides,Menidia beryllina; and Microtox® 15 min EC50s were conducted with: 1) streamwater, 2) untreated ground-water, 3) feedwater used in the ultrafiltration system and 4) permeate water that passed through the ultrafiltration system.A concentration of 100% streamwater caused significant (α⩽0.05) teratogenic responses in fish embryos and larvae; the Microtox® EC50 was 3.7% streamwater. Groundwater and feedwater caused significant embryo toxic or teratogenic responses at concentrations of 100, 10, and 1%; the Microtox EC50s were 0.85 and 0.48%, respectively. In contrast, only 100% permeate water caused significant increases in terata, compared to the control response; at 10 and 1% concentrations >90% of hatched larvae appeared normal. The Microtox EC50 was 30% permeate water.

Comparative acute sensitivities of early life stages of atherinid fishes to chlorpyrifos and thiobencarb.

Sensitivity, expressed as the 96-hr LC50 derived from acute lethality tests, was compared for four ages (day-of-hatch, 7-day, 14-day, and 28-day) of three atherinid fishes:Leuresthes tenais (California grunion),Menidia menidia (Atlantic silverside), andMenidia peninsulae (tidewater silverside). Responses of each age-species combination exposed to the organophosphate insecticide chlorpyrifos and the carbamate herbicide thiobencarb were compared in both static and flowing seawater toxicity tests. Chlorpyrifos was highly toxic to all atherinids (96-hr LC50s ranged from 0.4 to 6.7 μg/ L); toxicity of thiobencarb was approximately two orders of magnitude lower (LC50 values from 199 to 1,405 μg/L). Responses to each pesticide were similar among the three species. Sensitivity was generally highest for 7-day and 14-day age groups, and flowing water tests were more sensitive measures of toxicity than static tests, especially for chlorpyrifos. Comparisons of three computational methods indicate that probit and moving average methods calculate comparable LC50 estimates with the binomial method being the least uniform point estimator.

Oyster shell size and the selection of spawning sites byChasmodes bosquianus, Hypleurochilus geminatus, Hypsoblennius ionthas (Pisces, Blenniidae) andGobiosoma bosci (Pisces, Gobiidae) in two South Carolina estuaries

Utilization of empty oyster shells as a habitat and spawning substrate by the naked boby,Gobiosoma bosci, the striped blenny,Chasmodes bosquianus, crested blenny,Hypleurochilus geminatus, and freckled blenny,Hypsoblennius ionthas, was studied in the North Inlet and North Edisto River estuaries of South Carolina. Gape and length of shells occupied by fishes were measured. Fish inhabited and spawned in only a small portion of the size range of shells available.G. bosci, the smallest species studied, spawned in shells with narrower gapes than didC. bosquianus orH. geminatus and in shorter shells than didC. bosquianus. Thus,G. bosci may escape competition for spawning sites. Overall, there was a positive correlation between fish length and both gape and length of shells occupied by egg-guarding males.

Influence of environmental temperature on sex-ratios in the tidewater silverside, Menidia peninsulae (Pisces: Atherinidae)

Sex-ratios ofMenidia peninsulae from Santa Rosa Island, Florida were studied during a 13 mo survey. Monthly samples revealed significant deviations from the expected sex-ratio of 1:1. During May-Oct., young-of-year (YOY) females comprised 70-94% of the individuals collected in the 32.5-62.4 mm standard length (SL) size-class. These females were the presumptive progeny of reproduction at cold to cool fluctuating temperatures (14.1-24.2 C), during Feb.-April. In contrast, collections of YOY Menidia during Nov.-April yielded 35-60% females. These individuals were the presumptive progeny of reproductive activity and sexual differentiation in May-Aug. at warm fluctuating water temperatures of 23.5-31.5 C. The pattern in sex-ratios of older Menidia (62.5-102.4 mm SL) paralleled that of YOY individuals. Sex-ratios for combined (13 mo) collections of YOY were identical (69% females) to sex-ratios in older Menidia.

Toxicological assessment of biodegraded pentachlorophenol: Microtox® and fish embryos

A Gram-negative bacterium,Pseudomonas sp. strain SR3, was isolated from soil at a former wood treatment plant in north central Florida. The ability of this bacterium to degrade pentachlorophenol (PCP) was confirmed by growing cells in a basal salts medium in which PCP was the only source of carbon and energy. Degradation from a measured concentration of 39–40 μg PCP/ml to 0.0006 μg PCP/ml was observed within 120 h of incubation in the presence of PCP-induced cells ofPseudomonas sp. strain SR3. The initial cell density in these cultures was 6 x 106 cfu/ml. Microtox® 5 min EC50 toxicity tests revealed that aqueous solutions of PCP, measured concentrations 39–40 p μ/ml were toxic but that final biodegraded samples, 0.0006 μ/g PCP/ml were nontoxic. However, bioassays with embryonic inland silversides,Menidia beryllina, showed that the biodegraded samples were embryotoxic or teratogenic. Water containing added PCP at concentrations up to 30 times higher than measured in the final biodegraded samples was less toxic/teratogenic. These results indicate that while biodegradation of PCP was nearly complete, intermediate metabolites of the degradation process or undegraded impurities in PCP were toxic or teratogenic. Thus, theM. beryllina bioassay allows extremely sensitive assessment of toxicity associated with biodegraded environmental pollutants and may be a useful criterion for determining whether bioremediated water or soil is safe for discharge back into the environment.