Toxaphene bioaccumulation and translocation capacity was quantitatively evaluated in the Wolf River, Mississippi. Water, sediment, and fish samples were collected monthly and/or quarterly and evaluated for their role in accumulation and importance in translocating toxaphene. Water samples exhibited very low occurrence of toxaphene as determined by Gas-Chromatographic (G-C) analysis. The ability of water to expose both organisms and sediments to toxaphene, plus the role water plays in translocating toxaphene, are of minor importance Sediment samples collected within the Wolf River on a quarterly basis exhibited large variations in toxaphene levels from station to station as determined by G-C analysis, but no significant differences at stations over time. Prediction of toxaphene concentration in sediment samples from knowledge of either percent organic matter content, percent moisture content, or both of sediment samples was possible with statistical reliability Fishes collected and quantitatively measured from the Wolf River were found to be too variable in percent lipid content to significantly correlate with toxaphene concentrations in fishes. Measurements of wet weight, standard length, or both were able to predict toxaphene in species of fishes at a statistically significant level. Further, Notropis venustus (Cyprinidae) exhibited a higher capacity to accumulate toxaphene than did Lepomis megalotis (Centrarchidae), which exhibited a higher capacity to accumulate toxaphene than did Fundulus olivaceus (Cyprinodontidae). Each species of fish accumulated different concentrations of toxaphene in each quarter, and also accumulations of toxaphene by any one species fluctuated over time (quarterly collection periods) / acase@tulane.edu

The aryl hydrocarbon receptor (AhR) mediates toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a contaminant found ubiquitously in the environment. Teratogenic and carcinogenic activities of TCDD are well documented, however, little is known about the molecular basis of these actions. A transgenic zebrafish was developed that expressed green fluorescent protein (GFP) in the presence of AhR ligands. The time at which embryos were exposed to TCDD was critical to their survival. Exposure during the first 24 hours of development resulted in 100% mortality by 10 days post-fertilization, compared to 80% survival in control fish (0.01% DMSO). Comparable to controls, embryos exposed to TCDD (1 nM and 10 nM) after the first 15 hours of development exhibited 80% survival at 10 days post-fertilization. TCDD induced cranio-facial abnormalities in exposed animals. TCDD induced jaw dysmorphogenesis in 100% vs. 5% of fish when exposure was initiated at 1 or 15 hours post-fertilization, respectively. Control fish did not exhibit phenotypic aberrations. RTPCR detected mRNA expression for AhR and its dimerization partner, Arnt in unfertilized oocytes and at all developmental stages examined. Cytochrome P450 1A1 (CYP1A1) is an early biochemical marker of AhR action. A zebrafish cDNA fragment of CYP1A1 was cloned and used to detect functional AhR in embryos. TCDD induced CYP1A1 mRNA by 15 hours post-fertilization. CYP1A1 protein and activity were detected at 3 days post-fertilization. Induction was dependent on the age of the embryo and state of hatch. Precocious hatching, induced manually or chemically, did not induce CYP1A1 activity prematurely, and inhibition of hatching prevented induction of activity. Data presented show that CYP1A1 is regulated differently in embryos than adults and that TCDD mediated toxicity was not CYP1A1 dependent. Alcian blue stain indicated that TCDD- and retinoic acid-induced jaw dysmorphogenesis were phenotypically similar and targeted Hox gene-regulated skeletal structures. TCDD-induced Hoxa-1 levels and broadened the region of Hoxb-1 expression as shown by Northern blot analysis and in situ hybridization, respectively. Disruption of Hox gene regulation suggests a novel mechanism by which AhR disrupts morphogenic development following TCDD exposure / acase@tulane.edu

Benthos was sampled approximately quarterly from June, 1979, to April, 1980, using a hand held Ekman grab sampler at five stations in Bayou Lacombe and three stations in Talisheek Creek. Both streams are located in St. Tammany Parish, Louisiana. These streams are highly colored and acid with a sand and gravel substrate. Three substrate parameters and seventeen physicochemical and physical stream parameters were measured concurrently with benthos sampling, and multiple discriminant function analysis was used to differentiate the factors most influential in describing benthos distributions in each stream The analysis was most successful in Bayou Lacombe in which three faunal regions were distinguished, two in nearly lentic environments (headwaters and mouth) and one in the lotic stream midsection. These groups were distinguished primarily using stream size and substrate parameters. The analysis had limited power in discriminating faunal groups in Talisheek Creek High water in the streams from mid-March through mid-April, 1980, allowed observation of the effects of flooding on benthos. The effects were more pronounced in the mid-section of Bayou Lacombe in which benthos was virtually eliminated Drift samples were taken at six hour intervals over one 24 hour period approximately monthly at one station in each stream from June, 1979, through July, 1980. Drift densities were low in both streams, and few taxa showed a tendency for behavioral drift. Higher drift densities in both streams occurred during summer and fall months although these differences were statistically significant only in Talisheek Creek / acase@tulane.edu

No description available.

I conducted a management assessment for the conservation of benthic resources harvested by small-scale hookah divers in the northern Gulf of California (NG), Mexico, and analyzed the reproductive ecology of the black murex snail. Open access to the fisheries, combined with national and international market pressure, fishing methods, and the timing of fishing activities have caused an evident decline in production, the use of new fishing zones, and a shift of fishing effort towards deeper areas. However, the organization of the diving sector and its initiatives to establish forms of regulation provide an opportunity to alleviate this situation. I conclude that comanagement has the potential to be an effective management system for the benthic resources of the NG, a system that could be facilitated by the sedentary and semisedentary nature of these resources. An informal type of co-management arena is already in place with the possibility of being formalized and solidified.

The conservation of marine ecosystems is at least 20 years behind terrestrial and freshwater ecosystems due to the difficulties in studying and monitoring these dynamic and complex environments. Furthermore, marine environment receive less attention because human impacts are less visible in the sea, and oceans are viewed as global commons. The purpose of the present dissertation is to contribute to the knowledge of marine conservation through the development of three components in natural resources management: inventory, monitoring, and assessment of impacts. I elaborate a multi-taxa inventory, identify key species to monitor, characterize one of the key species, and assess the impacts of the most important fishery in the community-based controlled marine area of the Seri Indians along the Sonoran desert coast of Mexico. A total 657 species of mollusks, echinoderms, sharks, rays, bony fish, sea turtles, sea snake, aquatic birds and marine mammals were recorded in the Seri territory through review of 30 scientific collections housed in museums and universities, literature, and field collections. The fish information was improved through the analysis of 151 traditional Seri names. Fifty species were identified for monitoring ecosystem health. They represent species with a legal status, rare, commercially important, taxa that dominate or characterize entire communities, common taxa, and species recognized in the Seri culture. The annual eelgrass (Zostera marina atam) was selected as a key species inside the Canal de Infiernillo in the Seri territory. Coverage of the eelgrass beds was estimated using aerial photographs, field mapping, and Seri traditional ecological knowledge. The total extent of the eelgrass beds was approximately 6687 ha, which regrew in the same areas during the three-year study, maintaining the same general shapes and sizes. Twenty-six percent of the eelgrass beds overlap with the swimming crab (Callinectes bellicosus) fishing zones. Major impact on this fishery are caused by "ghost" fishing traps, which continue to capture crabs and animals and modify the substrate as they are moved around by currents and accumulate on the sea bottom. Efforts to standardize the use of traps will reduce these impacts on this fishery in the long term.

The discharge of untreated aquaculture effluent can pollute receiving water bodies. I tested the feasibility of using salt-tolerant plants (halophytes) with potential as forage and oilseed crops, as biofilters to treat saline aquaculture effluent. Plants were grown in draining lysimeters in greenhouses and irrigated with effluent salinized with NaCl. Irrigation water came from a recirculating tilapia culture system. I measured yield potential, water use and capacity for nitrogen and phosphorus uptake. In Experiment 1, Suaeda esteroa, Salicornia bigelovii and Atriplex barclayana (Chenopodiaceae) were grown in sand in 0.02 m³ lysimeters. Plants were irrigated with effluent of 0.5 ppt, 10 ppt and 35 ppt salinity, to meet evapotranspiration demand and to allow 30% of the applied water to leach past the plant root zone. Despite the high leaching fraction and short residence time of water in the pots, the plant-soil system removed 98% and 94% of the applied total and inorganic nitrogen, respectively, and 99% and 97% of the applied total and soluble reactive phosphorus respectively. For all species, salt inhibited (P ≤ 0.05) the growth rate, nutrient removal, and volume of water the plants could process. The salt marsh species S. esteroa and S. bigelovii performed better than the desert saltbush, A. barclayana, at 35 ppt. In Experiment 2, Suaeda esteroa, was grown in lysimeters containing approximately 0.8 m³ sandy loam soil and irrigated three times per week with 31 ppt NaCl effluent. I used five irrigation treatments, ranging in volume from 50 to 250% of the potential evaporation rate. Plant biomass and water consumption increased significantly (P ≤ 0.05) with increasing irrigation volume. Nitrate concentrations in water draining from the lysimeters decreased during the experiment, and were significantly lower in the high-volume treatments than in the low-volume treatments. Phosphorus concentrations in the leachate water increased during the experiment as a function of increasing irrigation volume. Irrigating halophyte crops with aquaculture wastewater of seawater-salinity may be a viable strategy for disposal of effluent.

The purpose of this dissertation was to characterize virulence, genomic and protein composition of a newly emerged virus of penaeid shrimp: white spot syndrome virus (WSSV). A partial genomic library, covering approximately 30-50% of the genome, of WSSV isolated from crayfish Orconectes punctimanus, was constructed by digesting viral DNA with endonuclease ClaI and cloning into the system pBluescript-JM109. Three viral inserts of approximately 2.2 kb, 2.8 kb and 6.3 kb, named as QW245, CR44, and QW237 respectively, were sequenced and analyzed. Six geographic isolates of WSSV, from China, India, Thailand, South Carolina, Texas, as well as from crayfish obtained from the US National Zoo in Washington D.C. were compared by electron microscopy (TEM) and SDS-PAGE. All viral isolates contained three major polypeptides of 25, 23 and 19 kDa. A fourth major polypeptide at the 14.5 kDa position was observed in four of the viral isolates. The 19 kDa polypeptide of the crayfish WSSV appeared larger in size than that of the other isolates. Amino acid composition of four of the major structural polypeptides of the South Carolina WSSV was analyzed. The NH₂ terminal amino acids of the 25, 23 and 14.5 kDa polypeptides of the SC WSSV were sequenced as MDLSFTLSVVTA, MEFGNLTNLDVA, and VARGGKTKGRRG, respectively. The genomic composition of the six geographic isolates of WSSV were compared by combining the methods of restriction analysis using nine endonucleases AccI, BglII, ClaI, BamHI, EcoRI, HindII, HaeI, SacI, XhoI and Southern blot hybridization applying three digoxigenin-11-dUTP labeled WSSV genomic probes LN4, C42 and A6. No distinctive difference among five WSSV isolated from penaeid shrimp was detected; differences were observed in the crayfish isolate of WSSV. The virulence of the six geographic isolates of WSSV were compared by per os challenge of Litopenaeus vannamei postlarvae and juveniles, and Farfantepenaeus duorarum juveniles. The Texas WSSV caused higher and more rapid mortalities; the crayfish WSSV caused lower and less rapid mortalities. L. vannamei postlarvae and juveniles were very susceptible to WSSV infection, while Fa. duorarum juveniles showed moderate resistance.

I quantified microhabitat conditions used by Yaqui chub (Gila purpurea), Yaqui topminnow (Poeciliopsis occidentalis sonoriensis), and beautiful shiner (Cyprinella lutrensis) on the San Bernardino National Wildlife Refuge, Arizona. Different species and different lifestages used different microhabitats. Smaller fish selected shallower water than adults. Yaqui topminnow and Yaqui chub showed seasonal variation in microhabitats used. Yaqui topminnows were found closer to cover when in the presence of beautiful shiners. Close proximity to cover may indicate a negative interaction. Yaqui chubs did not use microhabitats differently when in the presence of the other two species. Microhabitats used by Yaqui chubs in the ponds and Leslie Creek did not differ. Yaqui chub preferred pools with little or no flow. Management of aquatic environments on the refuge should focus on vegetative thinning. Stocking of beautiful shiner with Yaqui topminnow should be postponed until further research is conducted on the interactions between the two species.

<p> In the present study, a form of endocrine disruption that impacts production of the important stress and metabolic hormone, cortisol, was confirmed in southern California English sole (<i>Parophrys vetulus</i>) and further characterized using cellular and molecular approaches. One of the key initial findings of the study was that the interrenal itself, when tested directly for its <i>in vitro</i> response to pituitary ACTH, was non-responsive in fish exhibiting the endocrine-disrupted phenotype. This pointed directly to a dysfunctional interrenal gland in the impacted fish. With this knowledge in hand, a proteomics-based approach was employed to screen for changes in tissue protein expression. This experimental effort resulted in the molecular identification of 107 proteins, 83 of which were from unique genes, and it elucidated a variety of changes in protein expression related to interrenal function and to exposure of the fish to specific kinds of anthropogenic environmental chemicals.</p>