Phenotypic plasticity is the ability of the single genotype to pruduce multiple phenotypes in response to evironmental conditions. There are many factors affecting phenotypic plasticity. The aim of this thesis is to summarize the current knowledge of phenotypic plasticity of aquatic insects with emphasis on the role of temperature and food availability. The review is complemented by a laboratory experiments designed to investigate the effect of temperature and food availability on growth and development rate of diving beetle Acilius canaliculatus (Coleoptera: Dytiscidae). The results are discussed in the light of the ecological concepts of temperature-size rule and developmental isomorphy.

Phenotypic plasticity is the ability of the single genotype to pruduce multiple phenotypes in response to evironmental conditions. There are many factors affecting phenotypic plasticity. The aim of this thesis is to summarize the current knowledge of phenotypic plasticity of aquatic insects with emphasis on the role of temperature and food availability. The review is complemented by a laboratory experiments designed to investigate the effect of temperature and food availability on growth and development rate of diving beetle Acilius canaliculatus (Coleoptera: Dytiscidae). The results are discussed in the light of the ecological concepts of temperature-size rule and developmental isomorphy.

Many ecological and evolutionary processes have been described underlying natural selection but supporting evidence in wild settings is often lacking and our understanding remains incomplete. Using a multi-scale approach, I investigated expression of facultative den behavior (denning) among and within ursid species. Among species, lack of denning behavior was supported by relaxation of selection pressures of seasonal food availability due to realization of two sources of ecological opportunity; colonization of new habitat and adaptation of key innovations. Of denning species, I found evidence of adaptive ecological plasticity in den chronology among and within populations consistent with relaxed selective pressures influencing seasonal food availability and energetic budgets. I supported these finding using indices of fitness and established ecological theory. Further knowledge of organismal response to selection pressures has practical applications in predicting responses to novel and fluctuating pressures and aids in our understanding of the complexities of ecology and evolution.

<p>Populationer av öring består av både migrerande och stationära individer, och det tycks vara både genetiska och miljömässiga faktorer som påverkar en individs beslut att vandra eller ej. Syftet med denna studie var att testa vilken effekt tillgång på föda har på tillväxt och smoltifieringsprocess hos öring (Salmo trutta). Min hypotes var att öring med hög tillförsel av mat växer bättre och smoltifieras därmed inte till samma grad som öring med låg tillförsel av mat. Som en konsekvens av skillnader i mattillgång förväntades att ATPas-aktiviteten, vilken indikerar smoltstatus, var lägre vid god tillförsel av mat än vid låg tillförsel. Experimentet utfördes från november 2003 till april 2004 vid fiskeodlingen i Brattfors, Värmland, där 2+ Klarälvsöringar utsattes för tre olika födonivåer, med fyra replikat av varje födonivå. Var 4-5 vecka fångades fisken för att vägas och mätas och slutligen togs biopsi på öringens gälar för en analys av Na+,K+ -ATPas aktivitet. I slutet av experimentet klassificerades fiskarna som parr eller smolt.</p><p>Parr hade en signifikant lägre Na+, K+ -ATPas aktivitet än smolt i de tre olika födonivåerna. Na+, K+ -ATPas aktiviteten visade dock ingen signifikant skillnad mellan födonivåerna. Parr hade ökat sin vikt och längd mest i samtliga födonivåer och störst skillnad var det i den lägsta födonivån, parr hade ökat i genomsnitt 17 g och 3,5 mm mer än smolt. Av de två högsta födonivåerna var andelen klassificerade som smolt 37 % och vid den lägsta födonivån var andelen smolt 76 %.</p> / <p>Populations of brown trout consist of both migratory and resident individuals, and it is likely that both genetic and environmental factors influence the decision to migrate. The purpose of this study was to test the effect of food availability on growth and the smolting process in brown trout (Salmo trutta). My hypothesis was that brown trout subjected to a high food supply grows better and smoltifies to a lesser degree than brown trout subjected to a low food supply. As a consequence of differences in food supply I expected that ATPase-activity, which indicates smoltification status, would be lower with a high food supply than with a low supply. The experiment was run from November 2003 until April 2004 in a fish hatchery in Brattfors, Värmland, where 2+ brown trout from the river Klarälven were exposed to three food levels, each replicated four times. Every 4-5 weeks the fish were weighed and measured and a biopsy was taken from the gills for analysis of Na+, K+ -ATPase activity at the end of the experiment. At the end of the experiment the fish were classified as parr or smolt.</p><p>Parr had a significantly lower Na+, K+ -ATPase activity than smolt for the three different food treatments. Na+, K+ -ATPase activity did not differ significantly between food levels. Parr grew faster (both weight and length) than smolt at all food levels, and the largest difference between parr and smolt was observed at the lowest food level, where parr increased on average 17 g and 3,5 mm more than smolt. At the two highest food levels the proportion classified as smolt was 37 % and at the lowest foodlevel the proportion of smolt was 76 %.</p>

Food supply has been suggested as the main determinant of reproductive success in birds. Riparian species can take advantage of seasonal pulses of both terrestrial and aquatic prey, though aquatic resources are often overlooked in studies of diet and reproductive ecology. This study investigates the flux of both aquatic (mayfly) and terrestrial (caterpillar) prey resources and nestling diet of the Prothonotary Warbler throughout the breeding season in two eastern Virginia sites. One site had significantly higher aquatic prey (mayfly) availability. Nestling diet was generally reflective of prey availability, and nestlings grew faster at the site with high aquatic prey availability. At the site with low aquatic prey availability, nestling growth rates and condition were positively correlated with the amount of aquatic prey in the diet. Our results provide evidence that aquatic subsidies are an important resource for nestlings, and are crucial to understanding the breeding ecology of riparian species.

Populationer av öring består av både migrerande och stationära individer, och det tycks vara både genetiska och miljömässiga faktorer som påverkar en individs beslut att vandra eller ej. Syftet med denna studie var att testa vilken effekt tillgång på föda har på tillväxt och smoltifieringsprocess hos öring (Salmo trutta). Min hypotes var att öring med hög tillförsel av mat växer bättre och smoltifieras därmed inte till samma grad som öring med låg tillförsel av mat. Som en konsekvens av skillnader i mattillgång förväntades att ATPas-aktiviteten, vilken indikerar smoltstatus, var lägre vid god tillförsel av mat än vid låg tillförsel. Experimentet utfördes från november 2003 till april 2004 vid fiskeodlingen i Brattfors, Värmland, där 2+ Klarälvsöringar utsattes för tre olika födonivåer, med fyra replikat av varje födonivå. Var 4-5 vecka fångades fisken för att vägas och mätas och slutligen togs biopsi på öringens gälar för en analys av Na+,K+ -ATPas aktivitet. I slutet av experimentet klassificerades fiskarna som parr eller smolt. Parr hade en signifikant lägre Na+, K+ -ATPas aktivitet än smolt i de tre olika födonivåerna. Na+, K+ -ATPas aktiviteten visade dock ingen signifikant skillnad mellan födonivåerna. Parr hade ökat sin vikt och längd mest i samtliga födonivåer och störst skillnad var det i den lägsta födonivån, parr hade ökat i genomsnitt 17 g och 3,5 mm mer än smolt. Av de två högsta födonivåerna var andelen klassificerade som smolt 37 % och vid den lägsta födonivån var andelen smolt 76 %. / Populations of brown trout consist of both migratory and resident individuals, and it is likely that both genetic and environmental factors influence the decision to migrate. The purpose of this study was to test the effect of food availability on growth and the smolting process in brown trout (Salmo trutta). My hypothesis was that brown trout subjected to a high food supply grows better and smoltifies to a lesser degree than brown trout subjected to a low food supply. As a consequence of differences in food supply I expected that ATPase-activity, which indicates smoltification status, would be lower with a high food supply than with a low supply. The experiment was run from November 2003 until April 2004 in a fish hatchery in Brattfors, Värmland, where 2+ brown trout from the river Klarälven were exposed to three food levels, each replicated four times. Every 4-5 weeks the fish were weighed and measured and a biopsy was taken from the gills for analysis of Na+, K+ -ATPase activity at the end of the experiment. At the end of the experiment the fish were classified as parr or smolt. Parr had a significantly lower Na+, K+ -ATPase activity than smolt for the three different food treatments. Na+, K+ -ATPase activity did not differ significantly between food levels. Parr grew faster (both weight and length) than smolt at all food levels, and the largest difference between parr and smolt was observed at the lowest food level, where parr increased on average 17 g and 3,5 mm more than smolt. At the two highest food levels the proportion classified as smolt was 37 % and at the lowest foodlevel the proportion of smolt was 76 %.

AN ABSTRACT OF THE THESIS OF Benjamin S. Lewis Jr., for the Master of Science degree in ZOOLOGY, presented on December, 2, 2015 at Southern Illinois University Carbondale. TITLE: DETERMINING FOOD RESOURCES FOR AMERICAN BLACK DUCKS WINTERING AND SPRING STAGING ON THE EASTERN SHORE OF VIRGINIA MAJOR PROFESSOR: Dr. Michael W. Eichholz I evaluated food availability and food preference for American black ducks (Anas rubripes) wintering and spring staging on the Eastern Shore of Virginia during 2006–2007 and 2007–2008. I estimated food availability by taking core and sweep net sample at 78 sites selected by a stratified random sample throughout our study area, representing 4 dominant wetland habitat types. Seed and invertebrate biomass found in each of these samples were converted to measurements of kilograms per hectare. I found that salt marsh and mudflat habitats contained the highest amount of invertebrate biomass, while freshwater habitats contained the highest amount of seed biomass. I estimated food preference by collecting crop samples from 76 foraging black ducks. Animal matter made up 73% of the aggregate percent biomass of all foods eaten by black ducks. Foods found in black duck crops were compared to their availability in the environment and classified as either selected for, avoided or consumed relative to their availability. Although they were not found to be the most abundant foods, amphipods (Gammarus spp), salt marsh snails (Melampus bidentatus) and ribbed mussels (Geukensia demissa) were foods selected for in black duck wintering habitats. These food items are found most predominantly in salt marsh and mudflat habitats. As may be expected these areas are identified as the most important habitats for black ducks wintering on the Eastern Shore of Virginia. Results from this study provide energetic supply data for bioenergetically based habitat conservation for black ducks in Virginia and in the Atlantic Flyway. I found that the density of food items available for wintering black ducks were lower than densities found in in the more northern wintering range of the black duck and considerably lower than estimates from the wintering regions of other species of dabbling ducks. By concurrently measuring food selection and availability I was also able to reliably determine food preference. Removing avoided food items from food availability estimates provides more accurate estimates of preferred food biomass and it is important for bioenergetically based habitat models to use estimates of preferred food biomass in determining habitat objectives. I found that when avoided food items are removed, estimates of available food biomass decrease substantially, (up to 97%) further emphasizing discrepancies in estimates of food availability between coastal black duck wintering areas and estimates from the wintering regions of other species of dabbling ducks.

Criteria used to characterize lotic salmonid habitat are often based on observed correlations between physical habitat characteristics and salmonid abundances. A focus on physical habitat features ignores other habitat components, such as an adequate supply of food that set the physiological limitations on salmonid growth and survival. This study outlines the development of a habitat assessment approach that focuses on how invertebrate food availability interacts with stream temperatures to determine salmonid growth potentials. Abundances of benthic and drifting invertebrate communities, stream temperatures, and juvenile steelhead trout (Onchorhynchus mykiss gairdneri) summer growth rates and abundances were measured within 10 distinct stream segments in central Oregon. Stream temperatures and growth rates were used as inputs for bioenergetics model simulations to produce estimates of O. mykiss summer consumption rates. Measures of invertebrates providing the best description of food availability were chosen based on their ability to explain observed variation in salmonid consumption. Much of the variation in O. mykiss consumption estimates was explained by measurements of total drift biomass along a type II predator response curve. A random effects analysis of variance (ANOVA) was used to partition variation in invertebrate abundances across spatial and temporal scales. Quantification of variation at multiple scales allowed identification of a relevant spatial scale at which to assess macroinvertebrates relevant to salmonid populations, and compare the precision associated with measures of benthic and drifting invertebrate abundances. Results suggested that spatial variation in drifting and benthic invertebrate abundances are greatest at the scale of streams. Total drift biomass and total benthic biomass were more precise at the stream and stream reach scale than drift and benthic density. The information provided by this study will be used to guide the development of sampling approaches that describe invertebrates in a manner more directly related to salmonid production.

No description available.

Briery Creek Lake (BCL) has low abundance of young largemouth bass (LMB) compared to Sandy River Reservoir (SRR), which could jeopardize the trophy-LMB management goal in BCL. I assessed factors that may limit recruitment of LMB in BCL: angling, predation, competition, growth, and food availability. Age-0 LMB were monitored from nesting through their first summer with nest surveys, light traps, and electrofishing. Nesting success was higher in BCL (53%) than SRR (31%). Initial light trap catch-per-unit-effort (CPUE) was higher in BCL than SRR but, by July, light trap and electrofishing CPUE was higher in SRR than BCL. LMB nest success, growth, and CPUE did not differ between areas in BCL that were experimentally closed and areas left open to angling. Predation on age-0 LMB did occur in BCL, but was not higher than predation in SRR. Diet overlap between age-0 LMB and bluegill in BCL was >60% during June, indicating potential for competition. Zooplankton samples indicated that density of copepods was similar between reservoirs (2.3/liter); however, the average size of copepods was smaller in BCL (0.42 mm) than SRR (0.71 mm). I examined the activity of trypsin, which digests and converts protein. Trypsin activity was lower in BCL than SRR on 23 and 27 June, indicating that a nutritional deficiency exists for age-0 LMB in BCL. This deficiency was likely caused by the reduced zooplankton size in BCL and led to slower growth of age-0 LMB during June in BCL (0.8 mm/day) than SRR (1.2 mm/day). The fact that age-0 LMB CPUE in BCL dropped lower than SRR by July, despite BCL having a greater nesting success and higher CPUE in early June, indicates that a recruitment bottleneck for LMB occurred in June. Maintaining the trophy LMB fishery in BCL requires management options that consider the factors in June that affect recruitment. I recommend decreasing the presently overabundant aquatic macrophytes in BCL, thus allowing for increased nutrient availability for phytoplankton, the primary food source of zooplankton. This could increase the density and size structure of zooplankton, and thereby increase food availability for age-0 LMB. / Ph. D.