Neal P. Thompson

AN EPIZOOTIC OF WATERFOWL ASSOCIATED WITH A RED TIDE EPISODE IN FLORIDA 1

During February and March, 1974, an epizootic involving lesser scaup (Aythya affinis) occurred in the Tampa Bay area on the west coast of Florida. Several thousand ducks are estimated to have died. Concurrent with this epizootic was a red tide caused by heavy blooms of the toxic dinoflagellate Gymnodinium breve which caused severe wide-spread fish kills. Clinical signs consistent with G. breve intoxication were evident in some of the lesser scaup. A controlled experimental feeding of G. breve toxic material to White Pekin ducklings produced illness and death with signs comparable to some of those seen in the scaup.

Polychlorinated biphenyls and p,p' DDE in green turtle eggs from Ascension Island, South Atlantic Ocean.

Industrial pollutants are known to be widely distributed in global ecosystems. Polychlorinated biphenyls (PCBs), a representative of these pollutants, have been demonstrated in marine ecosystems of the North Atlantic Ocean and adjacent waters (DUSTMAN et al. 1971, JENSEN et al. 1969, ZITKO 1971) as well as California and Panama waters (RISEBROUGH et al. 1968a). In the majority of these reported occurrences the PCBladen organisms resided in waters that presumably also contained industrial pollutants, including PCBs. Similarly, persistent pesticides are of widespread occurrence, perhaps more so than the PCBs; for example, DDT and its metabolites have been identified in terrestrial, freshwater, and marine organisms of the Western world including remote Antarctica (BREWERTON 1969, GEORGE and FREAR 1966).

Residues of chlorinated hydrocarbons in tissues of raptors in Florida.

Dead or moribund raptors (n = 75) representing 11 species were collected between 1971 and 1981 from various locations in Florida. Samples of brain, muscle, liver and adipose tissue were analyzed for DDT, DDE, DDD, dieldrin, and PCBs. Detectable concentrations of DDT or its metabolites were found in 100% of all samples of muscle and liver, and 77% all samples of brain. Dieldrin was determined to be present in 91%, 93%, 87% and 78% of all samples of brain, muscle, liver and adipose tissue, respectively. Lethal or hazardous concentrations of dieldrin were found in brain samples from three birds, but DDT and PCBs were present at sublethal concentrations. When species were grouped according to their dietary habits, it was not possible to identify any trends in pesticide concentrations.

INTUSSUSCEPTION IN A FLORIDA MANATEE1

An intussusception resulting from an embedded fishhook and a mass of nylon cord, monofilament line, and wire was determined to be the cause of death in a Florida manatee (Trichechus manatus latirostris). Pathologic findings are given along with information on bacteria (Edwardsiella tarda), pesticide residues (DDE, PCBs, and dieldrin), and parasites (Chiorchis fabaceus).

Dislodgeable residues of ethion in Florida citrus and relationships to weather variables

Five different treatments of ethion on Valencia orange trees were compared for decay rates and for ethion monoxon and ethion dioxon production under different environmental conditions. The oxon metabolite levels observed were low and always below the residue level of ethion itself. There were no significant differences in the decay rates of ethion between treatments.A model of ethion decay utilizing environmental variables as a time base is presented. This model explains 94% of the variation observed in ethion decay during very wet and very dry periods in Florida.The application of these results and general experimental approach to worker safety reentry standards is discussed.

Evidence for metal poisoning in acute deaths of large red drum (Sciaenops ocellata).

Two of the approximately 100 large, mature, red drum found dead or dying in Floridas Indian River and Mosquito Lagoon were examined. Determinations were made of serum electrolyte concentrations, total proteins, albumins, globulins, creatinine values, and enzyme activity. Concentrations of copper, zinc, arsenic, chromium, cadmium, mercury, lead, and selenium were determined by atomic aborption. The outstanding histological lesions were found in the gills of a moribund specimen. Results indicate that the acute episode was triggered by ingestion of copper, zinc, and arsenic. However, cadmium, mercury and chromium may have been contributory by binding with metallothionein and thus lowering tolerance to metal poisoning. (JMT)

Disappearance of dislodgable residues of five organophosphate pesticides on citrus leaves and fruit during dry and wet weather in Florida

Citrus leaf discs and fruit taken from trees sprayed at recommended levels and twice recommended levels with ethion, parathion, azinphosmethyl, carbophenothion, and dioxathion were shaken with water and wetting agent for removal of dislodgable residues at 0, 1, 3, 5, 7, 14, and 21 days following treatment. The first portion of the field experiment was performed during a period of no rainfall (April) and the second when there was rainfall (July) in 1973. Four replicates of 50 leaf discs and 4 fruit, respectively, were averaged from each sampling to give data reported. A gas Chromatograph equipped with a flame photometric detector was used for analysis. Dislodgable residues found decreased with increasing time following application and samples from the wet period were lower than those from the dry period. Moisture and temperature could account for the differences in the two sampling periods.

Starvation-pesticide interactions in Juvenile Brown pelicans

SummaryNineteen 9-week-old brown pelicans (Pelecanus occidentalism), obtained from a colony in Vero Beach, Florida, containing environmentally acquired p,p′-DDE residues, were subjected to a food deprivation experiment. Samples of brain, liver, muscle, and fat taken after one and two week periods of starvation indicated that starved birds contained significantly greater residue levels in fat compared to non-starved controls. Such differences were not observed in residues in the other tissues. The significance of these findings is discussed in relation to the biology of brown pelicans.

Chlorinated hydrocarbon residues in the diet and eggs of the Florida Brown Pelican

Since the late 1950s the population of Brown Pelicans (Pelicanus occidentalis) in the United States has experlenced a substantial decline. The last nesting of the native Louisiana population occurred in 1961 (Williams and Martin, 1969). Schreiber and Delong (1969) described population declines and reproductive failure in California. Beckett (1966) reported a declining population in South Carolina. Hildebrand and Blacklock (unpublished report) reported a reduction in the population nesting on the Texas Coast. Only the Florida population has remained relatively stable (Williams and Martin, 1970).

Effect of long-term feeding of DDT to turkeys

SummaryDiets containing 264.6 ppm o,p′- or p,p′-DDT were fed to 6-week-old male and female turkeys for 7 and 15 weeks. Such chronic feeding of DDT did not cause alterations of: Blood pressure; gross structure of body tissues; histology of heart, aorta, liver, testes, oviduct, ovary, thyroid, or kidney; plasma cholesterol or calcium levels; albumin-globulin ratio; or plasma lipoprotein patterns. The residue of DDT in body fat was determined. Trace amounts were found in birds fed the control diet. Minute quantities of o,p′-DDT and large amounts of p,p′-DDT were found in fat of turkeys fed p,p′-DDT, and the converse was true of turkeys fed o,p′-DDT.