Southern flounder (Parlichthys lethostigma) is a recreationally and commercially important flatfish species found in the Gulf of Mexico, and recent analyses indicate that the northern Gulf of Mexico population is in decline. For proper management, knowledge of habitats used throughout the juvenile stage is needed. The aim of the current study is to examine habitat use of young-of-year (YOY) southern flounder in the Galveston Bay complex using habitat distribution models and acoustic telemetry. A set of habitat distribution models examined how habitat use changes during the first year of life. In addition, southern flounder were tagged with acoustic telemetry transmitters and monitored with a novel receiver array that allows for measurements of fine-scale movements. These movements were compared to habitat maps to examine habitat selection. Habitat distribution models determined that habitat requirements for southern flounder change with ontogeny and season. Newly settled southern flounder were most influenced by physicochemical parameters and the presence of seagrass beds. YOY southern flounder, however, showed increased occurrence at freshwater inlets during summer and fall months, and occurrence decreased at tidal inlets during the fall. Predictions of habitat suitability across the Galveston Bay complex indicate that the factors influencing occurrence of southern flounder change with season, ontogeny, and availability of suitable habitats. With acoustic telemetry, it was apparent that habitat use by southern flounder was nonrandom and influenced by benthic and other physicochemical conditions. Habitat analyses indicated that southern flounder used sand habitats more frequently than seagrass, oyster reef, or salt marsh habitats. Telemetry results also indicated that depth and water temperature were important determinants of habitat suitability for YOY southern flounder, with individuals preferring deeper and cooler regions of the water column in Christmas Bay. Both model and telemetry analyses indicate that habitat use by YOY southern flounder is dynamic across multiple spatial and temporal scales, with distributions and movements influenced strongly by ontogenetic changes in habitat associations, temporal and spatial variability in physicochemical conditions, and tidal cycles.

Nest survival often is lower at habitat edges than in habitat cores because of greater nest predation and parasitism near edges. I studied nest survival of breeding birds in bottomland hardwood forests of the lower Roanoke River, North Carolina. Nesting success was monitored in two forest width classes: narrow bands of levee forest that were dominated by two edge types, and wide, continuous levee forest stands that have edges but most forest is relatively far from edge. Nest success of Acadian Flycatchers and Prothonotary Warblers was similar in narrow and wide levees; nest success of Northern Cardinals was greater in narrow levees. Results of my study indicate that edge effects are not universal, and that amount of contrast at edges may interact with landscape context to alter ecological processes, such as nest predation. Bird populations are remarkably constant over time relative to other taxa, implying strong regulation. Avian population ecologists, however, have not studied regulatory mechanisms as often as seasonal limiting factors. Conversely, avian behavioral ecologists seldom emphasize the population dynamic consequences of habitat selection and reproductive success. This study describes the intersection of individual behavior and population regulation in the context of a new model of population regulation, site dependence, which is based on characteristics of breeding sites and behavior of individuals. I studied habitat distribution, age structure, reproductive output, and breeding site fidelity of Prothonotary Warblers (Protonotaria citrea) in two different bottomland hardwood forest habitats of the lower Roanoke River in North Carolina. Older males (³ 2 yr old) were equally common in cypress-gum swamps and mixed oak hardwood levee forest. Pairing success and success of first nests indicated that older males occupied the most suitable territories available in each habitat. Bird density was three times greater in swamps, and birds nesting in swamps averaged greater clutch sizes and fledged more young per nest than birds in levees. Greater reproductive output was the result of greater fecundity because nest survival and predation pressure appeared equal in the two habitats. Annual return rates for plot immigrants vs. previous residents did not differ in swamps. In levees, newly arriving birds were less likely to return the following year than previous residents. Immigrants most likely occupied low quality sites and dispersed in an attempt to improve breeding site quality. Habitat-specific demography and density patterns of this study indicate ideal preemptive distribution. Variance in site quality, between and within habitats, and preemptive use of sites are consistent with theory of population regulation via site dependence. Foraging behavior often reflects food availability. For example, in habitats where food availability is high, predators should move more slowly and attack prey more often than in habitats where food availability is low. I studied the foraging behavior of breeding Prothonotary Warblers in two habitat types to assess relative food availability and implications for habitat quality. The two habitats, levee and swamp forest, differ in hydrology, forest structure, and tree species composition. I quantified foraging behavior with focal animal sampling and continuous recording during foraging bouts. I measured two aspects of foraging behavior: 1) prey attacks per minute, using four attack types (glean, sally, hover, strike), and 2) number of movements per minute (foraging speed), using three types of movement (hop, short flight [£ 1 m], long flight [>1 m]). Male warblers made significantly more prey attacks per minute in swamp forest than in levee forest; the same trend was evident in females. Foraging speed, however, was not different between habitats for males or females. Results indicate that foraging effort is similar in swamps and levees, but that warblers encounter more prey in swamps. Greater food availability may be related to greater reproductive success of warblers nesting in cypress-gum swamps than in coastal plain levee forest. / Ph. D.

A field survey for the invertebrate fauna conducted in the Ma River, Thanh Hoa province in 2013. The research applied multivariable analysis performed by the Primer v.6 software, such as CLUSTER, one-way ANOSIM, BEST and DIVERSE. The results showed a list of 138 aquatic invertebrate species. Of these, most were freshwater wide-distributing species coupled with others characterized for brackish and marine waters. The biodiversity status was quite high compared to several other rivers in the North of Vietnam. The list contained many economic-valued species and 2 of these were listed in the Red Data Book of Vietnam. The aquatic invertebrates showed a significant relation to the two different combinations of physiochemical factors for zooplanktons and zoobenthos, respectively. The values of the species number, abundance and Shannon-Weiner index for both of zooplanktons and zoobenthos showed a curved trend from the upper river segments to lower river segments. These figures for zooplanktons peaked in the middle river segments, whereas the numbers for zoobenthos achieved the highest numbers in the estuaries. The species composition of the estuaries differentiated significantly from that of other freshwater habitats. / Năm 2013 đã tiến hành một đợt điều tra khu hệ động vật không xương sống sông Mã, tỉnh Thanh Hóa. Nghiên cứu sử các phân tích đa biến thông qua phần mền Primer v.6, bao gồm: CLUSTER, one-way ANOSIM, BEST và DIVERSE. Kết quả phân tích thu được 138 loài với thành phần loài chủ yếu là những loài nước ngọt thường gặp và phân bố rộng, ngoài ra còn có các loài đặc trưng cho nước lợ và mặn. Trong số các loài thu được, nhiều loài có giá trị kinh tế và 2 loài có tên trong Sách Đỏ Việt Nam. Khu hệ động vật không xương sống sông Mã có quan hệ chặt với hai nhóm chỉ số thủy lý hóa học khác nhau, tương ứng cho động vật nổi và động vật đáy. Giá trị các chỉ số sinh học gồm số lượng loài, mật độ và Shannon-Weiner hồi quy theo đường cong phi tuyến từ thượng lưu tới hạ lưu; đạt giá trị cao nhất tại cửa sông đối với động vật đáy và vùng trung lưu với động vật nổi. Thành phần loài cửa sông khác biệt rõ rệt với thành phần loài các sinh cảnh nước ngọt khác.

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A field survey for the invertebrate fauna conducted in the Ma River, Thanh Hoa province in 2013. The research applied multivariable analysis performed by the Primer v.6 software, such as CLUSTER, one-way ANOSIM, BEST and DIVERSE. The results showed a list of 138 aquatic invertebrate species. Of these, most were freshwater wide-distributing species coupled with others characterized for brackish and marine waters. The biodiversity status was quite high compared to several other rivers in the North of Vietnam. The list contained many economic-valued species and 2 of these were listed in the Red Data Book of Vietnam. The aquatic invertebrates showed a significant relation to the two different combinations of physiochemical factors for zooplanktons and zoobenthos, respectively. The values of the species number, abundance and Shannon-Weiner index for both of zooplanktons and zoobenthos showed a curved trend from the upper river segments to lower river segments. These figures for zooplanktons peaked in the middle river segments, whereas the numbers for zoobenthos achieved the highest numbers in the estuaries. The species composition of the estuaries differentiated significantly from that of other freshwater habitats. / Năm 2013 đã tiến hành một đợt điều tra khu hệ động vật không xương sống sông Mã, tỉnh Thanh Hóa. Nghiên cứu sử các phân tích đa biến thông qua phần mền Primer v.6, bao gồm: CLUSTER, one-way ANOSIM, BEST và DIVERSE. Kết quả phân tích thu được 138 loài với thành phần loài chủ yếu là những loài nước ngọt thường gặp và phân bố rộng, ngoài ra còn có các loài đặc trưng cho nước lợ và mặn. Trong số các loài thu được, nhiều loài có giá trị kinh tế và 2 loài có tên trong Sách Đỏ Việt Nam. Khu hệ động vật không xương sống sông Mã có quan hệ chặt với hai nhóm chỉ số thủy lý hóa học khác nhau, tương ứng cho động vật nổi và động vật đáy. Giá trị các chỉ số sinh học gồm số lượng loài, mật độ và Shannon-Weiner hồi quy theo đường cong phi tuyến từ thượng lưu tới hạ lưu; đạt giá trị cao nhất tại cửa sông đối với động vật đáy và vùng trung lưu với động vật nổi. Thành phần loài cửa sông khác biệt rõ rệt với thành phần loài các sinh cảnh nước ngọt khác.

<p>Diss. (sammanfattning) Umeå : Umeå universitet, 1995, härtill 6 uppsatser.</p> / digitalisering@umu