Evaporation ponds that dispose of agricultural drainwater provide attractive habitat for waterbirds but may result in contaminant exposure that impairs reproduction. I estimated post-hatching survival and evaluated productivity estimates for American avocets (Recurvirostra americana) nesting at evaporation ponds in the Tulare Basin, California from 1991 to 1993. Avocets and Black-necked stilts (Himantopus mexicanus) comprised the majority of 5,969 nests found. Nest success and embryo mortality varied among ponds and between species. Embryo deformity and mortality rates associated with selenium were higher in stilts. The majority of reproductive losses were attributed to predation, especially at ponds without islands. Post-hatch survival of radiomarked avocets after 5 weeks ranged from 0.375-0.729 and differed among ponds (log-rank X²=7.12, 2 df, P=0.028). Predation accounted for 55.4% (36/65) of known mortalities. Depredated chicks ranged from 1-30 days of age with a median age of 6 days. Arsenic concentrations in avocet livers were below detection limits while boron concentrations were below detection limits at Westlake-South (WLS) and Tulare Lake Drainage District-South (TLDD-S) in 1993. Mean boron concentration in livers was 3.7 ppm at TLDD-S in 1992 and 22.9 ppm at Lost Hills Water District (LHWD). Liver selenium concentrations increased with age and differed among ponds (P=0.0001). Mercury concentrations differed among ponds (P=0.0001), but were similar to background. Growth, survival and selenium exposure were consistent to support post-hatching effects of selenium. Mortality in avocet chicks was highest at LHWD, intermediate at TLDD-S and lowest at WLS, consistent with selenium exposures. I observed lower survival, histologic lesions, lower hatchling weights, slower growth, and elevated selenium and boron in tissue at LHWD. I used capture-recapture analysis also to estimate post-hatching survival and calculated avocet productivity. Survival estimates for the first 4 weeks post-hatching, based on model averaging, ranged from 0.572 to 0.751. Productivity at some ponds was insufficient to offset adult mortality. Estimates of average annual productivity were 0.49 and 0.45 in 1992 and 1993, respectively. Juvenile survival rates necessary for recruitment to offset 10% and 20% adult mortality ranged from 0.204 to 0.408 and 0.222 to 0.444, respectively. / Graduation date: 2004

Conventional methods for health assessment of wild-caught and stranded seals were used to describe the disease status of harbor seals in California. Clinical chemistry, infectious disease prevalence, immune function, and contaminant data were collected to evaluate harbor seal health with data collected from three groups of seals. Wild-caught seals of all ages were sampled at two locations: San Francisco Bay (a heavily urbanized estuary) and Tomales Bay (a less developed control site). Stranded seals entered rehabilitation from a more extensive portion of the California coast which included the locations where seals were caught. Hematology reference intervals were generated to provide a baseline for health assessment among the seals. Individual variability in blood variables among seals was affected by age, sex, location, and girth. Disease surveillance focused on pathogens known to cause lesions in harbor seals, zoonoses, and those with terrestrial sources. Specific pathogens of interest were E coli, Clostridium perfringens, Vibrio spp, Campylobacter spp, Salmonella, Giardia, Cryptosporidium, avian influenza virus, Brucella, Leptospira spp., Toxoplasma gondii, Sarcocystis neurona, and Neospora caninum, Leptospira spp, and phocine and canine distemper virus. There was evidence of exposure to all pathogens except for phocine distemper virus. Simple measures of immune response were used to evaluate the immune function of harbor seal pups in rehabilitation that had evidence of previous bacterial infection. The swelling response to a subcutaneous injection of phytohemagglutinin (PHA) was positively associated with growth rate, possibly illustrating the energetic trade-offs between growth and immunity. Blubber contaminant concentrations (PCBs, DDTs, PBDEs, CHLDs, and HCHs) in harbor seal pups were grouped by extent of suckling and strand location. The ratio of PCB:DDT was increased in San Francisco Bay and decreased in Monterey Bay compared with other locations along the coast. Pups that weaned in the wild, lost weight and then stranded had the highest contaminant levels, equivalent to the concentrations detected in stranded adult harbor seals. Dispersal and survival were monitored by satellite telemetry in harbor seal pups released from rehabilitation and recently weaned wild-caught pups to assess the effect of condition, health, and contaminant levels on survival probability. Increased contaminant levels and decreased thyroxine (T4) were associated with decreased survival probability. Increased mass, particularly among the rehabilitated pups, was associated with increased survival probability. This study demonstrates that health and survival of harbor seals pups along the central California coast are impacted by human activities such as contaminant disposal, pathogen pollution and boat traffic, although the variability in individual health measures requires carefully designed studies to detect these effects.

Although the use of pesticides is necessary to meet the socio-economic needs of many developing countries, especially in Africa, side effects of these bio-active chemicals have contributed to contaminating aquatic and terrestrial ecosystems. Environmental water quality degradation by pesticides interferes with ecosystem health and poses numerous risks to aquatic life. In South Africa, glyphosate-based herbicides are frequently used to control weeds and invading alien plants, but ultimately end up in freshwater ecosystems. However, there are no South African-based environmental water quality management strategies to regulate these bio-active chemicals. Therefore, this study sought to provide a sound scientific background for the environmental water quality management of glyphosate-based herbicides in South Africa, by conducting both laboratory and field investigations. In the laboratory investigations, aquatic ecotoxicological methods were used to evaluate responses of the freshwater aquatic shrimp Caridina nilotica exposed to Roundup® at different biological system scales, and the responses of multiple South African aquatic species exposed to Roundup® through species sensitivity distribution (SSD). In the field investigations, the effect of Kilo Max WSG on the physicochemical and biological conditions of three selected sites in the Swartkops River before and after a spray episode by Working for Water were evaluated through biomonitoring, using the South African Scoring System version 5 (SASS5) as a sampling protocol. Both Roundup® and Kilo Max WSG are glyphosate-based herbicides. All the data were subjected to relevant statistical analyses. Findings of this study revealed that Roundup® elicited responses at different biological system scales in C. nilotica, while SSD estimates were used to derive proposed water quality guidelines for glyphosate-based herbicides in South Africa. The biomonitoring revealed that using glyphosate-based herbicides to control water hyacinth within the Swartkops River had a negligible impact on the physicochemical and biological conditions. Based on these findings, a conceptual framework that can be used for the integrated environmental water quality management of glyphosate-based herbicides in South Africa was developed as part of integrated water resource management (IWRM). The combined data sets contribute to a sound scientific basis for the environmental water quality management of glyphosate-based herbicides in South Africa.

M.Sc. (Zoology) / Please refer to full text to view abstract