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Urban rivers face sustained anthropogenic pressures limiting biodiversity. Yet, urban waterways such as the Detroit River are important habitat in supporting regional diversity. The Detroit River is a Great Lakes Area of Concern where conservation and restoration efforts prioritize improved biological and habitat integrity in the connecting channel. This study explores benthic macroinvertebrate in submerged aquatic vegetation across five mainstem channel wetlands and two tributary sites of the Canadian wetlands to describe spatial patterns and diversity. We first examine inter-wetland differences between five mainstem wetlands by hierarchical cluster analysis, NMDS and PERMANOVA, identifying two mainstem groups: one comprising of two middle reach wetlands (Detroit River Marshes and Grass Island), the second showed similarities among wetlands across all reaches (Turkey Creek, River Canard and Peche Island). The latter groupings shared similar habitat characteristics, deeper and finer grain-sizes, and functional feeding group characteristics - low abundances of shredders. Second objective, we perform an intra-wetland comparison for Turkey Creek and River Canard to analyze for differences along tributaries. At neither River Canard nor Turkey Creek we observed significant tributary influence on mainstem communities but had found the Turkey Creek tributary communities significantly differed from the channel communities. Diversity metrics and Hilsenhoff Biotic Index illustrate strained benthic communities across the river. We had also found water quality to be consistently moderately degraded. Our findings differ from prior analyses within emergent vegetation that indicate variable water quality conditions between mainstem and tributary and non-impaired macroinvertebrate communities.

The Persian Gulf is a semi-enclosed marine system surrounded by eight countries, many of which are experiencing substantial development. It is also a major center for the oil industry. The increasing array of anthropogenic disturbances may have substantial negative impacts on marine ecosystems, but this has received little attention until recently. We review the available literature on the Gulf’s marine environment and detail our recent experience in the United Arab Emirates (U.A.E.) to evaluate the role of anthropogenic disturbance in this marine ecosystem. Extensive coastal development may now be the single most important anthropogenic stressor. We offer suggestions for how to build awareness of environmental risks of current practices, enhance regional capacity for coastal management, and build cooperative management of this important, shared marine system. An excellent opportunity exists for one or more of the bordering countries to initiate a bold and effective, long-term, international collaboration in environmental management for the Gulf.

This study investigated the relationship between stable nitrogen isotopes (δ 15 N) and polychlorinated biphenyl (PCB) concentrations in rock bass (Ambloplites rupestris) and bluegill sunfish (Lepomis macrochirus) with respect to age, size, and diet. δ 15 N signatures in both species exhibited enrichment with increasing size and approached steady state with respect to dietary δ 15 N values by the second year of growth. Young-of-the-year fish, however, exhibited lower nitrogen isotope enrichment over the diet, indicating that the commonly held trophic enrichment factor of 3.4‰ is more suitable for older, slow-growing individuals. PCB accumulation in both species progressed from being dominated by uptake from water in small (<100 g) fish to dietary uptake in larger individuals as a function of bioenergetic constraints such as food energy conversion and contaminant assimilation efficiencies. Significant increases in PCB accumulation were attributed to decreased specific growth rates such that ≤60% of body mass was gained on an annual basis. This effect was most noted in bluegills where higher PCB biomagnification factors were a consequence of increased foraging costs associated with an invertebrate diet. It is concluded that growth-related changes in species bioenergetics regulate both contaminant accumulation and δ 15 N dynamics.

Stable isotope and gut content analyses were completed on multiple age classes of Detroit River rock bass (Ambloplites rupestris) and bluegill sunfish (Lepomis macrochirus) to determine the importance of resource partitioning in littoral centrarchids. δ15N signatures ranged from$10.9\\textperthousand$to$12.8\\textperthousand$in young of the year (YOY) to 7-yr-old rock bass and from$10.3\\textperthousand to 12.1\\textperthousand$for YOY to 4-yr-old bluegills. YOY diets for both species had similar proportions of benthic and epiphytic prey, with YOY rock bass also having a planktonic dietary component. YOY rock bass consequently had a lighter δ13C signature than similarly aged bluegills, suggesting that these individuals are able to exploit prey from more energetically efficient open water habitats. Rock bass became piscivorous during the first full year of growth, with concomitant depletion of the δ13C signature with increasing age, typical of an isotopically depleted phytoplankton δ13C signal. By 7 yr of age, rock bass diets were dominated by crayfish and cyprinids, with no further significant depletion of the δ13C signature. For bluegills, diets were dominated by small benthic invertebrates, regardless of age. δ13C signatures in YOY and 1-yr-old bluegills remained enriched relative to rock bass of the same age, suggesting that bluegill sunfish remain in nearshore shallower littoral habitats for a greater proportion of their life history because of increased predation pressure. This pairing of stable isotope and gut content analyses provides a quantitative resolution of foraging history and habitat selection of species coexisting in a littoral community.

We determined polychlorinated biphenyl (PCB) elimination patterns in lake trout (Salvelinus namaycush) from Lake Ontario using biomonitoring data collected from 1977 to 1993. The in situ elimination rates of these persistent pollutants were found to describe tissue turnover rates in lake trout. A model relating tissue turnover rates and endogenous energy conversion efficiencies revealed that chemical elimination in larger organisms is primarily regulated by food limitation and bioenergetic mechanisms rather than chemical kinetics. Lake trout approximately 2500 g and larger were observed to have higher PCB elimination rates than smaller fish as a result of increased lipid mobilization to supplement metabolic demands due to increased time spent foraging. This study concludes that the growth and production of large predators in Lake Ontario are regulated by the bioenergetic constraints of searching for prey in a food-limited environment. We also demonstrate that persistent organic pollutant kinetics can describe the proportion of endogenous energy required to support metabolism and production, thus providing important in situ measurements of bioenergetic processes.

This thesis provides an examination of the toxicokinetics of polychlorinated biphenyls (PCBs) in birds. Experimental studies documenting the dietary bioavailability, plasma/fat distribution and elimination of individual PCBs were performed in two avian species, ring doves (Steptopelia risoria) and American kestrels (Falco sparverius). The assimilation of PCBs from food was highly efficient, independent of diet properties and weakly dependent on congener hydrophobicity. Blood plasma/fat distribution coefficients were constant with time and dependent on the relative lipid contents of the two tissues. Elimination of PCBs occurred by biotransformation, fecal egestion and egg production pathways and exhibited declining trends with increasing chemical hydrophobicity. For the persistent congeners, PCB elimination rates were regulated mostly by fecal egestion and egg production rather than biotransformation. The above studies were utilized to calibrate an open two compartment rate constant model in each species and to calibrate a fugacity based gastrointestinal absorption model in ring doves.

Abstract A total of 80 crossbred, high-risk heifers (initially 250 ± 4.2 kg BW), were transported from an Oklahoma City, Oklahoma sale barn to the Kansas State University Beef Cattle Research Center. Cattle were unloaded and randomly placed into one of four receiving pens and provided ad libitum hay and water. Each pen was randomly assigned to one of the four rest times before processing: (1) immediately upon arrival (0); (2) after a 6-h rest period (6); (3) after a 24-h rest period (24); and (4) after a 48-h rest period (48). After all cattle were processed, heifers were allotted into individual pens with ad libitum access to a receiving ration and water. Heifers were weighed individually on d 0, 7, 14, 21, 28, and 35 to calculate average daily gain (ADG). Feed added and refusals were measured daily to determine dry matter intake (DMI). A fecal egg count reduction test and analysis of blood serum metabolites were also conducted. All data were analyzed using the GLIMMIX procedure of SAS (v. 9.4, Cary, NC) with individual animal as the experimental unit. Processing time did not impact (P > 0.05) heifer BW or ADG. From d 0 to 35, DMI decreased linearly (P = 0.027) as rest time increased. The number of days for heifers to reach a DMI of 2.5% BW was linearly increased (P = 0.023) as rest time increased. There was no evidence of differences (P ≥ 0.703) among rest times for feed efficiency. While morbidity did not differ between treatments (P > 0.10), mortality increased linearly (P = 0.026) as the time of rest increased. A significant processing time × day interaction (P < 0.0001) was observed for the prevalence of fecal parasites, where the percentage of positive samples was significantly lower 14-d after anthelmintic treatment, regardless of the processing time. Serum IBR titer for heifers processed at either 0 or 6-h upon arrival was significantly higher (P < 0.01) on d 35 compared to d 0. Heifers processed after a 48-h rest period had significantly higher glucose values (P < 0.01) on d 0 compared to heifers processed at 0, 6, or 24-h. In summary, rest time prior to processing did not impact receiving calf growth performance. A 6-h rest period upon arrival appeared to be most beneficial to DMI. Anthelmintic treatment at processing reduced the parasitic load in heifers processed at all times. Vaccine titer did not increase after initial processing in heifers processed 24- or 48-h after arrival, indicating the seroconversion of IBR antibodies during the longer rest period.