The lower Chesapeake Bay and adjacent coastal waters serve as the primary summer nursery areas for juvenile sandbar sharks (Carcharhinus plumbeus) in the Northwest Atlantic Ocean. The large population of juvenile sandbar sharks in this ecosystem benefits from increased food availability that fuels rapid growth and from limited exposure to large shark predators. Juvenile growth and survival is the most critical life history stage for sandbar sharks, and juvenile nursery grounds will continue to play an important role in the slow recovery of this stock from severe population declines due to overfishing. The goal of this study was to assess the possible impacts of juvenile sandbar sharks as apex predators on the lower Chesapeake Bay ecosystem and to evaluate the energetic benefits of using this nursery. The bioenergetics model was used as a tool to predict energy consumption rates of individual sandbar sharks based on their energetic demands: metabolism, growth, and loss of waste. Metabolic rate is the largest and most variable component of the energy budget, particularly for species such as the sandbar shark that must swim continuously to ventilate their gills. The standard (basal) and routine metabolic rates of juvenile sandbar sharks were measured in two laboratory respirometry systems, using oxygen consumption rate as a proxy for metabolic rate. These data span the entire range of body sizes and water temperatures characteristic of the Chesapeake Bay population. Standard metabolic rates of sandbar sharks were similar to values obtained for related shark species by extrapolation of power-performance curves. The effects of body size and temperature on standard metabolic rate were similar to previous results for elasmobranchs and teleost fishes. In fifteen sharks, routine metabolic rate while swimming averaged 1.8 times the standard metabolic rate when the sharks were immobilized. Data obtained from the literature support the theory that limited gill surface areas and narrow metabolic scopes of many elasmobranchs help to explain their slow growth rates, since growth has the lowest rank of the multiple metabolic demands placed on the oxygen delivery system. These new metabolic rate data were then combined with other species-specific data to construct a bioenergetics model for juvenile sandbar sharks for the time they spend in Chesapeake Bay each summer. This model predicted higher daily rations than previous estimates for this species that were based on simple bioenergetics models or stomach contents and gastric evacuation rate models. However, the predicted rations agree with reconstructed meal sizes of juvenile sandbar sharks and are comparable to those of ecologically similar shark species. When extrapolated from individuals to the population level, the model predicted a negligible effect of predation by juvenile sandbar sharks on the lower Chesapeake Bay ecosystem; the consumption rate of juvenile sandbar sharks pales in comparison to other carnivorous fishes and to humans, the true apex predators in the system.

Only a miniscule fraction of the world’s largest volume of living space, the ocean’s mid-water biome, has ever been sampled. As part of the International Census of Marine Life field project Mid-Atlantic Ridge Ecosystems (MAR-ECO), a discrete-depth trawling survey was conducted in 2009 aboard the NOAA ship Henry B. Bigelow to examine the pelagic faunal assemblage structure and distribution over the Charlie-Gibbs Fracture Zone (CGFZ) of the northern Mid-Atlantic Ridge. This is the first MAR-ECO project aimed specifically at describing diel vertical migration as a distributional phenomenon. Discrete-depth sampling from 0-3000 m was conducted during both day and night in similar locations using a Norwegian “Krill” trawl with five codends that were opened and closed via a pre-programmed timer. Seventy-five species of fish were collected, with a maximum diversity and biomass observed between depths of 700-1900 m. An incremental gradient in sea surface temperature and underlying watermasses, from northwest of the CGFZ zone to the southeast, was mirrored by a similar gradient in ichthyofaunal diversity. Using multivariate analyses, eight deep-pelagic fish assemblages were identified, with depth as the overwhelming discriminatory variable. Strong diel vertical migration (DVM) of the mesopelagic fauna was a prevalent feature of the study area, though the numerically dominant fish, Cyclothone microdon (Gonostomatidae), exhibited a broad (0-3000 m) vertical distribution and did not appear to migrate on a diel basis. In all, 3 patterns of vertical distribution were observed in the study area: a) DVM of mesopelagic, and possibly bathypelagic, taxa; b) broad vertical distribution spanning meso- and bathypelagic depths; and c) discrete vertical distribution patterns. Overall species composition and rank order of abundance of fish species agreed with two previous expeditions to the CGFZ (1982-83 and 2004), suggesting some stability in the ichthyofaunal composition of the study area, at least in the summer. Frequent captures of putative bathypelagic fishes, shrimps, and squid in the epipelagic zone (0-200 m) were confirmed. The results of this expedition reveal distributional patterns unlike those previously reported for open ocean ecosystems, with the implication of increased transfer efficiency of surface production to great depths in the mid-North Atlantic.

The Ross Sea polynya is characterized by high spatial and temporal variability and by an annual cycle of sea ice retreat, water column stratification, large phytoplankton blooms, and months of complete darkness. This region is also highly susceptible to increasingly changing climatic conditions that will significantly affect the hydrography, iron supply, primary production patterns and carbon cycling. This project focused on analyzing how differences in photosynthetic traits between the two major bloom-forming functional groups in the polynya, diatoms and the prymnesiophyte Phaeocystis antarctica, and investigate if these differences can explain their dominance and succession. The study was conducted as part of the Controls on Ross Sea Algal Community Structure (CORSAC) program during two cruises in December 2005-January, 2006, and November-December, 2006. A fast repetition rate fluorometer (FRRF) was used to assess photochemical efficiency on natural phytoplankton assemblages and on monoclonal cultures. Measurements were made on cultures to determinate differences in photorecovery kinetics, as well on a suite of experiments performed to test the effects of temperature, iron, CO2 and micronutrients had on natural assemblages. In addition, FRRF measurements were made on 1,182 discrete samples representative of 98 profiles collected over the two cruises. Phaeocystis antarctica consistently photorecovered faster than the diatoms Pseudo-nitzschia sp., indicating different photosynthetic strategies and ecological niches; in addition, temperature and iron significantly promoted photosynthetic quantum yields, indicating a diffuse iron limitation of the natural assemblages used for the experiments and a high susceptibility to forecasted temperature increases in the region. Experiments also demonstrated that the Ross Sea phytoplankton is capable of maintaining high photosynthetic capacity after extensive periods in the dark. The dominance and successions in the blooms appears to be controlled by a combination of hydrography and in particular by the relative depths of the mixed layer and euphotic zone, as well by the water temperatures and possibly by iron concentrations. Diatom-dominated blooms were found in shallow mixed water layers characterized by higher temperature and fresher waters in the summer in the western part of the polynya, while Phaeocystis antarctica prevailed in colder regions with deeper mixed layer depths in the eastern part of the polynya. The dominance in the bloom significantly affected the relative macronutrient drawdown. Photosynthetic characteristic of natural assemblages were also modeled based on variable fluorescence rapid light curves (RLCs), and photophysiological differences were found between diatoms and Phaeocystis antarctica, with the latter having higher Ek and lower functional absorption cross sections (sigmaPSII) and alpha values, but similar maximum electron transport rates (ETRs). Lastly, correlation between RLC-based modeled photosynthetic rates and 14C based primary production presented some discrepancies due to limitations and differences in methodologies.

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No description available.

A total of 1665 larval caddisflies, representing four families and eight genera, was collected from seven stations in the Drake's Creek drainage from 1 November, 1982 through 15 October, 1983. The pattern of longitudinal distribution of the larvae, based on feeding relationships, in the West and Middle Forks of the system was consistent with studies by Wiggins and Mackay (1978), Andrews and Minshall (1979), and Ross and Wallace (1982) and the River Continuum Concept (Vannote et al. 1980). The Trammel Fork, a spring fed stream, showed a pattern of distribution contrary to the predictions of the Concept, suggesting that the continuous gradient of physical conditions upon which the Concept was based may not be present in streams where hypogean inflows constitute a major part of the water volume. One larva collected represented a new species record for Kentucky. Light trap collections of adult caddisflies yielded 28 species representing eight families and 15 genera, suggesting an extremely diverse trichopteran fauna in the Drake's Creek drainage. In addition, the first reported species records for Trichoptera in Allen and Simpson Counties as well as 21 additional records for Warren County were established. Three of the species of adult Trichoptera reported represented new species records for Kentucky.

The reproductive biology of the paddlefish (Polyodon spathula) was studied on specimens collected from Lake Cumberland, Kentucky, from September 1983 to July 1984. A total of 500 specimens was studied. Reproductive activity was observed on 17 April 1984 in the Big South Fork of Lake Cumberland. Seasonal differences were observed in sex ratios with more males than females occurring in the winter and spring. Movements were observed throughout the year, but these were accentuated prior to reproduction in the spring. Lake Cumberland paddlefish became sexually mature by Age Group V in males and VIII in females. In the spring, gravid females were found only in upstream spawning areas while non-gravid females occurred throughout the rest of the lake. This supported the alternating year spawning hypothesis for females of this species; mature males were found in all lake locations sampled at this time. Gonad development in Lake Cumberland paddlefish started in September-October and continued progressively throughout the year until egg release. Gonad fat bodies responded inversely with gonad development, progressively decreasing in size as the gonads increased. The liver and throat fat bodies did not show this weight correlation but were concluded to be important in the energetics of the gonads. Coefficients of condition for Lake Cumberland paddlefish corresponded closely with gonad development. Condition values for Lake Cumberland paddlefish were greater than those reported in the literature. This supported the idea that the optimum habitat for paddlefish is in lakes rather than rivers. The estimated average annual fecundity for Lake Cumberland paddlefish was similar to that reported in other studies. No relationship was seen between number of eggs and fish size. All sexually mature males and some females exhibited prominent secondary sexual characteristics.

A study of the phytoplankton periodicity and its correlation with chemicophysical parameters, diel variation of the plankton, and the cyclomorphotic variation of Ceratium hirundinella was made in Shanty Hollow Lake, Warren County, Kentucky, from October, 1969, to August, 1970. Phytoplankton samples were collected at zero and six feet with a Kemmerer sampler (31 October through 8 December) and with a ten -liter Birge-Juday plankton trap (23 December through 9 August). Water samples for the chemicophysical determinations were collected with a Kemmerer sampler. The phytoplankton samples were preserved with 5% formalin until they were enumerated. The chemicophysical determinations (pH, conductivity, dissolved solids, orthophosphate, silicon, turbidity) were performed immediately upon arrival at the laboratory. Temperature was recorded in the field. Statistical analyses of the phytoplankton and chemicophysical data indicated no differences among the three sites and between the two depths sampled on each sampling date. Asterionella formosa, Crucigenia tetrapedia, Ankistrodesmus spiralis, and Dinobryon sertularia were observed to be cool water species; Ceratium hirundinella and Mallomonas caudata were observed to be warm water species. Trachelcmonas spp. populations varied with the temperature with about a two -month lag between the initial temperature change and the subsequent population change. Measurements of Ceratium hirundinella individuals from four sampling dates indicated that with an increase in water temperature, the overall length of the cells, the number of horns, and the length of the apical horn decreased, while the width of the cells increased. Phytoplankton and zooplankton samples were collected from a single station every four hours over a 24 -hour period. Statistical analyses of the data revealed no differences in numbers of plankton among the sampling times, but differences in numbers of plankton among the depths. Polycystis aeruginosa densities were low throughout the study possibly because the pH of the water was too low for optimum growth. Asterionella formosa and Dinobryon sertularia maxima coincided with concentrations of silica above 0.5 mg/1, while the populations of these organisms varied inversely with the concentrations of orthophosphate. Conductivity and dissolved solids were at a maximum following the decline of the Aphanizomenon flos-aquae bloom on 3 July. Turbidity was also at a low at this time. A high concentration of orthophosphate and a low concentration of silica coincided with the bloom.

Observations were made on the appearance and development of anatomical features such as neural receptors (free neuromasts and taste buds), lateral line canals and bone elements of the mandibular and hyoid regions of the skull associated with the larval stages of the spotted bass (Micropterus punctulatus) and northern hog sucker (Hypentelium nigricans). The results were related to known feeding habits and habitat selection. Free neuromast development and appearance of the lateral line canal system in the spotted bass preceded that of the northern hog sucker. This accelerated development of the spotted bass was related to earlier activity in feeding, including piscivory, and presence among emergent shoreline vegetation. The northern hog sucker was more sedate in occupying quiet rock-outcrop shoreline areas. It was found to exhibit more diverse feeding habits. Taste buds played a secondary role in early larval ecology being present throughout all developmental stages and showed little importance in early feeding compared to free neuromasts. The taste buds present on the hyoid region of the northern hog sucker indicated a future bottom feeding habit. The teeth on the basihyal and jaw bones of the spotted bass larvae supported its early predaceous habit. The development of jaws in the northern hog sucker at the start of the mesolarval stage was the most important developmental feature relating to the onset of exogenous feeding.

An ecological study of the invertebrate animal forms exclusive of microscopic forms found in the waters of Drakes Creek in Warren County, Kentucky, was undertaken for the purpose of determining both the nature and amount of invertebrate animal life found in these waters. The Kentucky Fish and Game Commission has made several plantings of game fish in the waters studied. However, the fishermen report no appreciable increase of the fish life in these waters. In view of the failure of the fish to propagate properly in these waters, and because the other physical factors appeared favorable for the propagation of game fish, it was believed that food might be a limiting factor in the propagation of fishes in these waters. An ecological study was therefore made of the invertebrate animal forms exclusive of microscopic animals found in these waters at different depths and under different physical conditions. No ecological studies seem to have been made of the waters of Drakes Creek. In addition to the above stated objective, it therefore seemed desirable to make a general study of the animal forms exclusive of microscopic forms independent of the problem of food supply for game fish.