Browsing by Subject "diet"

Now showing 1 - 5 of 5
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    Cholesterol: Why am I taking a statin and what I need to watch
    (2009-05-04) Olson, Matthew D.
    Now clinicians have an additional approach to treating patients with combined hyperlipidemia, defined as elevations in both triglycerides and LDL, when statin monotherapy cannot appropriately correct triglyceride levels. This does not necessarily correlate to decreased disease progression.
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    Dietary Niche and Growth Rate of the Nonnative Tubenose Goby (Proterorhinus semilunaris)
    (2019-05) Dawson , Bradley
    Basic life history knowledge is essential to determine if a nonnative species is potentially invasive. The nonnative tubenose goby (Proterorhinus semilunaris) arrived in the Great Lakes in the 1990s via ship ballast water, but remains poorly studied within North America, making it difficult to predict its effects on native ecosystems. Diet and growth patterns were examined from age-0 tubenose gobies within the estuary of the St. Louis River, a tributary to Lake Superior near Duluth, Minnesota. Dietary breadth and growth rates have important ramifications for survival, competitiveness, and dispersal ability of a fish species, influencing its potential success as an invasive species. I sampled tubenose gobies from shallow vegetated habitat via beach seine during summer and fall periods, and removed otoliths and aged fish on daily increments for growth modelling. Furthermore, stomach contents were identified and weighed to provide measures of fitness and dietary breadth between seasons (fall vs. summer) and between several locations within the estuary. Results suggest a low dietary breadth that overlaps with tadpole madtom (Noturus gyrinus); tubenose goby diet was mostly comprised of Crustacea, regardless of location or season. Growth modelling demonstrates that tubenose gobies reach a small maximum size and are short-lived, indicating an r-selected life history. The Gompertz function is preferred for modelling the growth of this species.
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    Fishing Cat Ecology: Food Habits, Home Ranges, Habitat Use and Mortality in a Human-Dominated Landscape around Khao Sam Roi Yot, Peninsular Thailand
    (2015-06) Cutter, Passanan
    Abstract Despite their global status as an endangered species, many aspects of fishing cat (Prionailurus viverrinus) ecology have not been studied in detail in the wild. The objectives of this study were to understand food habits, habitat use, home range patterns, and causes of mortality in a predominantly agricultural landscape in the area in and around Khao Sam Roi Yot National Park, Prachuap Khiri Khan Province, peninsular Thailand. Few studies have been conducted on the food habits of wild fishing cats and none has been conducted in Southeast Asia. I identified prey remains in fishing cat scats to estimate composition and relative occurrence of major prey groups in the feces of 194 fishing cat scats collected over an approximately 35 km2 area. The proportion of prey remains found in scats was 42% fish, 24% mammals, 24%, birds, 5% reptiles, and 2% crustaceans. There was a significant difference in seasonal prey composition (p = 0.001). During the dry season, 47% of prey remains found was fish, 11 % mammal, 29% bird, 11% reptile, and 3% crustacean. In the wet season, proportions were 36% fish, 39% mammal, 20% bird, 2% reptile, and 1% crustacean. In this study, fishing cat diet varied more than previously reported, both in terms of the diversity of prey and in the proportions of major groups recorded between seasons. To study the home range, habitat use, and mortality of fishing cats, I captured seventeen cats (seven females and 10 males) using box traps and fitted 16 with VHF radio collars. Data from these animals (>1000 locations) were used to estimate home range size and habitat selection. Home range size was estimated using 100% Minimum Convex Polygon (MCP) and the 95% Fixed Kernel (FK) methods. Fishing cats essentially maintained their core area for the duration of the study despite seasonal changes in diet. For the 100% MCP, the area of the male annual home range, F5 was 13.5 km2 and M8 was 4 km2 and the mean for female annual home ranges (n=4) was 4.0 km2. Whereas, the 95% estimates for the male annual home range was 8.8 km2, and the mean annual home range for females was 3.9 km2. Seasonal home range was estimated for one male. His wet season 100% MCP was 10.8 km2, and his 95% fixed kernel was 12.6 km2. In the dry season his 100% MCP home range was 5.7 km2 and the 95% fixed kernel home range was 8.9 km2. For females (n=4), mean wet season 100% MCP home range was 3.2 km2 and the mean 95% fixed kernel was 3.1 km2. The dry season mean 100% MCP was 3.0 km2 and the mean 95% fixed kernel was 3.2 km2. There is evidence of overall home range overlap between females but their 50% area had no overlap. Fishing cats used aquaculture areas and rice fields more frequently, than mangrove restoration areas, and coconut plantations, and human settlement and limestone hills were avoided. One animal used primarily mangrove vegetation (97% of all locations). Coconut plantation was a relatively rare vegetation type within the study area, but it was the most used habitat for one animal in the dry season. Of 16 cats originally collared, five died from confirmed poaching or retribution killing (31.3%), dead from unknown causes (n=6, 37.5%), unknown fate (n=3, 18.8%), and collar malfunction (n=2, 12.5%). Considering that fishing cats have been known to live to 10 years of age, the sample in this study sustained a relatively high mortality rate. Because poaching and retaliatory killing was the main cause of death, the most effective conservation effort for this species in coastal Thailand should focus on decreasing human-fishing cat conflict and poaching.  
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    Growth and Predatory Demand of Cisco (Coregonus artedi) in Western Lake Superior
    (2017-01) Harding, Ian
    Lake Superior’s food web has been altered in recent decades by changes in fish populations as well as species invasions. In addition, warming surface waters may also effect food web interactions. Cisco (Coregonus artedi) is an abundant and important planktivorous fish in Lake Superior. Cisco link secondary production to top level predators and support a viable commercial fishery. However, it is unknown how these changes to the Lake Superior ecosystem have effected cisco growth rates and resource use in Lake Superior. I reconstructed growth histories of cisco from western Lake Superior from 1984-2013 and used bioenergetics modeling to explore how cisco have responded to changes in their density, the invasion of spiny water flea (Bythotrephes longimanus), and climate change. I also used bioenergetics modeling and concurrent estimates of calanoid copepod standing stock and production to estimate the current supply-demand relationship for this important prey resource of cisco in Lake Superior. Cisco growth rates have been relatively stable over the 25-year period analyzed in this study with the exception of the 1998 cohort. The 1998 cohort had reduced growth rates in comparison to other cohorts analyzed in this study which may be the result of a density dependent reduction in prey resources. Climate change and invasion by spiny water flea may not have effected cisco growth rates to date, however, bioenergetics modeling suggests spiny water flea are a poor prey item for cisco relative to native prey and could reduce growth rates of cisco that consume them. Cisco were the primary consumers of calanoid copepods in the offshore waters of Lake Superior in 2014-2015 and consumption of calanoid copepods by fish was approximately 15% of calanoid production from May 2015-October 2015. Cisco may have exerted top-down control on calanoid copepods from October 2014-May 2015 which could have increased intraspecific competition for prey resources during this time. This work helps to clarify how cisco have responded to perturbations to the Lake Superior food web. In addition, this work suggests cisco in western Lake Superior are not currently prey limited during the growing season (May-October). They may however, exert top-down control on their winter prey resource. Future studies concerning the winter ecology of cisco and calanoid copepods may improve our understanding of resource use by this important planktivore in Lake Superior.
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