Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 220-229). / Also available by subscription via World Wide Web / vi, 229 leaves, bound 29 cm

Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 220-229).

We monitored distribution and abundance of food resources and determined food habits of nonbreeding bald eagles (<i>Haliaeetus leucocephalus</i>) on the northern Chesapeake Bay, as a preliminary step toward examining food-base effects on bald eagle distribution and abundance. To correctly interpret our food habits results, we first examined biases of 2 commonly-used food habits techniques, pellet analysis and food remains collection, through feeding trials with 2 captive bald eagles. Eagles were fed a variety of food items found on the northern Bay. Egested pellet contents and frequency of remains were compared with actual diet. We also examined efficacy of direct observation by observing eagles in high-use foraging areas. We found pellet analysis accurately indicated the species of birds and mammals eaten, but overrepresented medium-sized mammals and underrepresented large carrion in percent occurrence results. Fish were poorly represented in pellets. Eagles rarely produced pellets after eating fish, suggesting that pellet egestion rate, defined as the number of pellets produced per eagle per night, can serve as an index to relative use of birds and mammals. Food remains collection was highly biased toward birds, medium~sized mammals, and large, bony fish. Direct observation was labor intensive and required close proximity of the observer for unbiased identification of food items. Observation may be the only means of documenting eagles' use of small, soft-bodied fish. We used direct observation, pellet analysis, and pellet formation rates to determine bald eagle food habits from December 1986 through April 1988. We monitored fish abundance by gill netting and waterfowl abundance by aerial surveys over this same period. Fish and waterfowl abundance varied reciprocally; waterfowl numbers peaked in winter and fish numbers peaked in spring and late summer. Bald eagles responded to differences in food abundance with diet shifts. Canada geese (<i>Branta canadensis</i>), mallard (<i>Anas platyrhynchos</i>), and white-tailed deer (<i>Odocoileus virginianus</i>) carrion were primary foods from November through February. Cold-stressed gizzard shad (<i>Dorosoma cepedianum</i>) were captured frequently by eagles below a hydroelectric dam on the Susquehanna River in November and December, and also were taken frequently throughout the study area during a winter when ice cover was extensive. Shad were not commonly available during a milder winter. From April through September, bald eagles fed on a variety of fish species, primarily gizzard shad, channel catfish (<i>Ictalurus punctatus</i>), Atlantic menhaden (<i>Brevoortia tyrannus</i>), white perch (<i>Morone americana</i>), American eel (<i>Anguilla rosfrata</i>), and yellow perch (<i>Perca flavescens</i>). The 4 most commonly consumed fish species also were the most commonly gill netted species. At least 25% of all fish taken were scavenged. Live fish were most abundant at the water's surface in shallow water. Bald eagles' use of live fish reflected this availability; water depth at live fish capture sites was less than at sites where fish of dead or unknown status were taken. Eagles foraged most intensively within 1 hour of sunrise. A second smaller peak in foraging activity was observed in early afternoon. / Master of Science

I studied bald eagle (Haliaeetus leucocephalus) distribution, abundance, roost use and response to human activity on the northern Chesapeake Bay from 1984-89. The eagle population consisted of Chesapeake breeding eagles, Chesapeake nonbreeding eagles, northern-origin eagles and southern-origin eagles; changes in overall eagle distribution and abundance reflected the net changes in these 4 groups. Breeding territories on the northern Chesapeake increased from 12 to 28 from 1984 to 1988. Breeding eagles were resident all year, always ~7 km from the nest. Chesapeake nonbreeding eagles moved throughout most of the bay, but rarely left it (~5% of the radio-tagged eagles were off the bay during any month). Northern eagles migrated into the bay in late fall (x = 21 December! n = 7! range = 61 days) and departed in early spring (x = 27 March, n = 14, range = 43 days). Southern eagles arrived on the northern bay throughout April-August (x = 6 June, n = 11, range = 94 days) and departed from June - October (x = 3 September, n = 22, range = 119 days). Northern Chesapeake eagle abundance peaked twice annually; in winter (261 eagles, December 1987), driven by the presence of northern eagles, and in summer (604 eagles, August 1988), driven by the presence of southern birds. Of 1,117 radio-tagged eagle locations, only 55 (4.90/0) occurred in human-developed habitat, which composed 27.7% of 1,442 km2 of potential eagle habitat on the northern Chesapeake Bay (P < 0.001). During 36 aerial shoreline surveys, eagles were observed on only 111 of 700 (15.9%) 250-m shoreline segments that had development within 100 m, whereas eagles were observed on 312 of 859 (36.30/0) segments when development was absent (P < 0.001). On average, eagles were observed on 1.0 segment/survey that had coincident pedestrian use within 500 m, compared to 3.6 segments/survey expected if eagles and pedestrians were distributed along the shoreline independently (n = 34 surveys, P < 0.001). / Ph. D.

Although agricultural pesticide use is suspected of being a major contributor to the risk of toxic contamination of the Chesapeake Bay, little information concerning the nature and extent of that risk is available. Such information is essential, however, for setting pesticide risk management priorities and for designing policies to reduce the risk of toxic pollution from agricultural sources. To help meet the information needs of Bay region water quality Management, a model of agricultural pesticide risk is developed and used to assess pesticide risk in Virginia’s Chesapeake Bay Region. The information generated by the model includes: an inventory of which chemicals are used; where they are used; estimates of aggregate chemical use for counties and crops; and an evaluation of the potential adverse environmental effects of that use. This information is provided for both current (1990) and future (2000) pesticide risk. An econometric model of land use in the Bay region is used to predict acreage in various crops to which pesticides will be applied in 1990 and 2000. Next, acreage estimates are combined with pesticide application rates to yield estimates of aggregate use of each pesticide. Finally, environmentally relevant characteristics of the pesticides (toxicity, persistence, mobility, etc.) are used to evaluate the potential environmental risk associated with that use. The policy implications of this modeling are then explored. Particular attention is paid to the potential for targeting of pesticide risk management programs at chemicals, sub-regions, or production systems (i.e. crops) that represent the greatest risk of toxic contamination of the Chesapeake Bay. Results indicate that while urbanization in the Chesapeake Bay region will reduce the amount of land devoted to crop production, the reduction in the acreage to which pesticides may be applied will not greatly reduce pesticide risk in the near future. The risk evaluation effort reveals that pesticide risk is highly concentrated in small subsets of the crops grown in the Bay region, of the pesticides used on those crops, and of the counties located in the region. / Master of Science

Research was conducted in soils of the Chesapeake Bay area primarily to determine the combined effects of tillage practice and N fertilizer application rates on N leaching and denitrification losses from corn fields. Three well known models - the NTRM, CERES- Maize, and VT-MAIZE - were also tested to determine their predictive ability of N distribution in soil and crop, the various components of the N cycle, and corn yields. To accomplish the above objectives, two field sites were located (in 1986) for a 3 year study on agronomically important and representative soils that are used for corn production in the Chesapeake Bay drainage basin. The main plot treatment was tillage and consisted of no-till and conventional-till. The subplot treatments were N application rates which consisted of 6 levels with 4 inorganic and 2 organic (sewage sludge) N fertilizers. Denitrification experiments were also conducted on the Groseclose silt loam soil to estimate and compare N loss through denitrification from both till and no-till practices. C₂H₂ was used to inhibit N₂ production and N₂O was collected in closed chambers located on the soil surface. Tensiometers and neutron moisture meter access tubes were also installed to monitor soil moisture and energy levels. Nitrogen leaching losses were determined by applying the principle of N mass balance. Denitrification N loss during the corn growing season was less than 2% of the applied N fertilizer. The N losses from the two tillage systems were not significant at p > 0.10. If Fick’s law is to be applied for predicting N loss from the soil subsequent to C₂H₂ application, sampling must occur after a minimum preset critical time. In the Groseclose soil, there was an increase in both total yield and total N uptake when sewage sludge was applied compared to the split and preplant inorganic fertilizers applied at the same rate. There was no difference in yield or N uptake due to applying N as either preplant or a split application. Where no-till management was used, there was an increase in both yield and N uptake as compared with conventional tillage. In the Suffolk soil, tillage management did not influence yield or N uptake where time and source of N application were studied. The relationship between yield and N application rates for both soil types could be described with quadratic equations. The total N recovery could also be described with quadratic equations. However, these relationships do not hold every year for every season or tillage management practice. The no-till plots retained higher moisture content than conventional tillage plots in the upper 0-100 cm depth. Below 100 cm depth, however, no-till retained less than conventional till. The gain and loss of N in soil was dependent on the tillage type and seasons of the year. During the growing season, generally the conventional tillage gained more N than the no-till. During winter, however, the N losses due to leaching were proportional to the amount of N retained at the end of the growing season. Thus, conventional tillage lost more N by leaching during the winter months. Mineralization of N was higher in conventional till, while denitrification was higher in no-till. Split application has shown less N loss due to leaching than the preplant. Mineralization, denitrification, and leaching took place from both the upper and lower zones of the soil profile. The model performances varied from year to year and from one tillage practice to another. Since they were generally written for average (normal) soil and climatic conditions, they did not make satisfactory predictions under the severe moisture conditions experienced during this study. Thus, they require a great deal of readjustment. Considering all aspects, however, the NTRM is the best model. The unmodified VT-MAIZE is the next best. / Ph. D.

The first objective of this research was to determine if pesticides were leaching into the shallow groundwater beneath agricultural sites, and if so, to determine a correlation between soil and groundwater pesticide concentrations. The second was to examine the correlation between pesticide concentrations measured by gas chromatography with electron capture detector (GC/ECD) and an immunoassay method developed by OHMICRON Corporation. Samples from four agricultural and one reference (undeveloped) site were analyzed for pesticides over an 11 month period from April, 1992 to February, 1993. One hundred and nineteen separate groundwater samples were analyzed for: alachlor, atrazine, carbofuran, cyanazine, and metolachlor. Pesticide analysis of groundwater and seepage meter water was carried out by immunoassay and by solid phase extraction (SPE) with octadecyl bonded extraction disks followed by GC/ECD. Fifty-five soil and sediment samples were Soxhlet extracted followed by gas chromatography/mass spectrometry (GC/MS). Pesticides were detected in 13.4% groundwater samples by GC/ECD with only one detection being greater than 1 ppb. The immunoassay method detected pesticides in 32% of the groundwater samples with the majority of these detections also being below 1 ppb. Alachlor and/or metolachlor were detected in 44% of the soil samples at concentrations ranging from 7 ppb to 485 ppb. The study concluded that the majority of the target pesticides were being adsorbed by the soil and only limited amounts, less than 1 ppb, were being transported to the groundwater. It was also concluded that the immunoassay had lower limits of detection, but may yield some false positive results. / Master of Science

The goals of this study were to elucidate relationships between food habits and tissue accumulations of heavy metals in Chesapeake Bay waterfowl and to determine effects of chronic cadmium and lead ingestion on energy metabolism in waterfowl. Concentrations of cadmium, lead, copper, and zinc were measured in 774 livers, 266 kidneys, and 271 ulnar bones from 15 species of ducks obtained from the Chesapeake Bay region. Liver and kidney concentrations of cadmium were highest among two carnivorous sea duck species, Clangula hyemalis and Melanitta deglandi. In contrast, lead concentrations in three tissues were generally highest in largely herbivorous species, such as Anas platyrhynchos, Anas rubripes, and Anas strepera. Spent shot may be an important source for tissue burdens of lead in these ducks. No marked trends were observed between food habits and tissue concentrations of copper or zinc. Cadmium and lead concentrations were generally higher in benthic macrophytes than in soft tissues of clams collected from several locations in the Bay. These results suggest that the change that has occurred in the food habits of some Chesapeake Bay ducks, most notably Aythya valisineria to diets composed largely of clams rather than aquatic vegetation probably did not increase ingestion of these elements. In experiments conducted with A. platyrhynchos, chronic ingestion of equal dietary concentrations of cadmium and lead resulted in about 15 times greater accumulation of cadmium than lead in livers and kidneys. However, while ulnar bones accumulated lead, cadmium concentrations in bones remained below detection limits. Cadmium ingestion enhanced renal accumulation of copper and zinc, perhaps due to induction of metallothionein by cadmium. In combination with an imposed food restriction, cadmium ingestion appeared to alter some indices of energy metabolism, such as plasma concentrations of free fatty acids and triiodothyronine, at dietary cadmium levels far below those eliciting similar responses in the absence of a food restriction. Those results suggest the importance of considering interactions with other stressors when examining potential effects of environmental contaminants on wild animals. / Ph. D.

The crab processing industry of the Chesapeake Bay region has, until recently, been able to dispose of their processing wastewaters by discharging them, largely untreated, directly to the receiving waters along which their plants are located. With the upcoming implementation of new NPDES discharge limits, this practice will no longer be possible. This study investigated the potential of two different technologies for treating the processing wastewaters. Bench-scale anaerobic contact type reactors were studied for effectiveness in the removal of organics from the processor’s wastewaters, and a pilot-scale countercurrent air stripping tower was studied for ammonia removal. Two anaerobic reactors which were fed retort process wastewater at F/M ratios of 0.35 and 0.25 lb COD/1b MLVSS/day, were found to achieve organics removals (on a BOD₅ basis) of 88% and 94% respectively. Similarly, a second pair of anaerobic reactors were fed a mixed wastewater, representative of a mechanized processing plant’s total wastewater flow, at F/M ratios of 0.10 and 0.07 lb COD/1b MLVSS/day. These reactors were found to achieve organics removals (on a BOD₅ basis) of 79% and 83% respectively. All four of the reactors were eventually shut down after exhibiting signs of failure. These failures were attributed to possible sodium and ammonia toxicity problems. The effectiveness of the air stripping tower in the removal of ammonia from retort process wastewater was tested in relation to liquid flow rate, influent temperature, and influent pH. A maximum ammonia removal of 71% was observed when treating a waste, with an influent temperature of 580C and pH level of 12.2, at an air-to-water ratio of approximately 825 ft³/gal. Similarly, an ammonia removal rate of 67% was observed while treating a waste, with an influent temperature of 650°C and pH level of 11.0, at an air-to-water ratio of approximately 412 ft³/gal. / Master of Science