The importance of zooplankton in the diets of blue runner (Caranx crysos) near offshore petroleum platforms in the northern Gulf of Mexico

Blue runner (Caranx crysos), common around offshore petroleum platforms in the Gulf of Mexico, were found to forage extensively on meso- and macro-zooplankton during the summer months. Larval decapods and stomatopods, hyperiid amphipods, pteropods, and larval and juvenile fishes were common components of their diet. Feeding periodicity results suggest that blue runner around platforms were capable of feeding throughout the night at the same intensity as the day. Size selectivity indicated that larger prey, such as fish were consumed during the night and smaller decapod crustaceans were consumed during the day. Blue runner collected from open waters away from platforms also consumed decapods and larval fish as well as other abundant zooplankton such as chaetognaths. Although certain zooplankton taxa exhibited increased densities near the platform during some cruises, plankton net sampling did not demonstrate consistently elevated densities of zooplankton in proximity to petroleum platforms. Zooplankton density was generally greater during the night samples, however a platform enhancement effect was not observed. Results from ADCP surveys suggested that zooplankton and ichthyoplankton contributed to the measured volume backscattering strength. Diel and between-cruise changes in zooplankton density were correlated with changes in acoustic scattering levels during acoustic surveys conducted around the platforms. These surveys demonstrated the utility of an ADCP to examine small-scale patterns in sound scattering layers in surface waters around platforms, however preliminary analysis did not establish that elevated (or reduced) levels of scattering existed near platforms. Examination of more surveys along with including data on current velocity will provide further insight into the localized effects of these structures. The net and acoustic data collected in this study suggested that more intensive sampling closer to platforms is needed to understand how these structures support large aggregations of fishes such as blue runner

Spatial changes in soil stable isotopic composition in response to carrion decomposition

Decomposition provides a critical mechanism for returning nutrients to the surrounding environment. In terrestrial systems, animal carcass, or carrion, decomposition results in a cascade of biogeochemical changes. Soil microbial communities are stimulated, resulting in transformations of carbon (C) and nitrogen (N) sourced from the decaying carrion soft tissues, changes to soil pH, electrical conductivity, and oxygen availability as microbial communities release CO2 and mineralize organic N. While many of the rapid changes to soil biogeochemistry observed during carrion decomposition return to background or starting conditions shortly after soft tissues are degraded, some biogeochemical parameters, particularly bulk soil stable δ15N isotopic composition, have the potential to exhibit prolonged perturbations, extending for several years. The goal of this study was to evaluate the lateral and vertical changes to soil stable isotopic composition 1 year after carrion decomposition in a forest ecosystem. Lateral transects extending 140 cm from three decomposition “hotspots” were sampled at 20 cm intervals, and subsurface cores were collected beneath each hotspot to a depth of 50 cm. Bulk soil stable isotopic composition (δ15N and δ13C) indicated that 1 year after complete soft tissue removal and decay, soils were significantly 15N enriched by 7.5±1.0 ‰ compared to control soils up to 60 cm from the hotspot center, and enrichment extended to a depth of 10 cm. Hotspot soils also contained 10 % more N compared to control soils, indicating that decomposition perturbs N pools. Our results demonstrate that carrion decomposition has the potential to result in long-term changes to soil biogeochemistry, up to at least 1 year after soft tissue degradation, and to contribute to bulk soil stable isotopic composition

Collaborating with Wheat Producers in Demonstrating Areawide Integrated Pest Management

Focus groups were used to initiate collaborative relationships with wheat producers while learning about their farming history and decision-making. Focus group transcripts illustrate that producers were less confident in evaluating insect management problems compared to weed management. Producers do rely on Cooperative Extension in managing insect problems. Extension educators continue to play an important role in increasing producer\u27s knowledge of simplified field scouting and insect identification technology

Seagrass Habitats as Nurseries for Reef-Associated Fish: Evidence from Fish Assemblages in and Adjacent to a Recently Established No-Take Marine Reserve in Dry Tortugas National Park, Florida, USA

Scientists and managers worldwide have increasingly advocated the use of marine protected areas (MPAs) to protect at—risk fish stocks. Most MPAs, however, have been established to protect reefs, while nonreef habitats, such as seagrasses, have received less consideration. In January 2007, an MPA called the Research Natural Area (RNA), was established as a no—take marine reserve in the Dry Tortugas National Park, Florida (DTNP), becoming the first MPA within the park boundaries to offer direct protection to seagrasses and reef habitat. We conducted a study using small—mesh Antillean Z—traps to (1) characterize fish assemblages in seagrass and reef habitats and (2) assess if differences in community structure existed between the RNA and adjacent open—use areas. Over 3 sampling events (Fall 2009, Spring 2010, Fall 2010), 3,163 individuals of 38 species were collected from 129 stations. Fish assemblages differed significantly among sampling events and between habitat types, but no differences were evident between the RNA and open—use areas. Unlike previous sampling efforts that focused on larger—bodied fish in the DTNP, Z—traps targeted small—bodied reef— and seagrass—associated fishes. Juvenile Haemulon plumierii and Epinephelus morio strongly contributed to community structure and were more abundant in seagrass habitats, which may serve as an important nursery area. Because the RNA was only established 2 years before this study was conducted, it could still be several years before benefits to the juvenile population become evident, but this study establishes the importance of consider-ing seagrass habitats when developing a reef—associated no—take marine reserve

Shallow-Water Coral Communities Support the Separation of Marine Ecoregions on the West-Central Florida Gulf Coast

Florida’s west coast is a 170,000 km2 bedrock shelf (west Florida shelf, WFS) comprised of north-south discontinuous carbonate outcroppings extending more than 200 km from the intertidal zone to a depth of 200 m. These outcrops support diverse benthic communities, which contribute to a multi-billion dollar recreational and commercial fishing industry, yet only about 5% of their extent has been studied in detail. Benthic communities shift over a 6.5° geographic range, but the locations of these shifts are not well-defined. Previous studies have suggested a break in biogeographic regions at Tampa Bay, south at Cape Romano, and north at Cedar Key. The goal of this study was to map and investigate the shallow WFS marine hardbottom north and south of Tampa Bay, FL to identify differences in benthic communities and identify ecoregion boundaries. Habitat mapping yielded 295.89 km2 of hardbottom which differed in extent between Sarasota and Pasco counties. Benthic surveys tabulated 4,079 stony coral colonies of nine species and 1,918 soft corals. Stony corals were dominated by Siderastrea radians, Oculina robusta, Solenastrea hyades, and Cladocora arbuscula less than 10 cm in diameter. Distinct differences in these communities were evident from south to north. The main community shift indicated an ecoregion boundary at, or very near, the mouth of Tampa Bay. Another shift associated with the Bahamas Fracture Zone (BFZ) occurred at the Pinellas and Pasco County border. The outputs of this work provide the first detailed benthic habitat map of the area, a detailed survey of the composition of hardbottom benthic communities in the region, identify Tampa Bay as a coastal benthic biogeographic transition, and illustrate the influence of the BFZ on coastal communities. These findings illustrate a need for additional WFS benthic research and mapping to give a more comprehensive understanding of coral community biogeography in the context of future warming conditions and the potential tropicalization. Unifying seafloor mapping data, mapping new areas with high probability of hardbottom resources, and collecting benthic community data over broader scales will refine community biogeographic zonation. This is a necessary precursor to any long-term community monitoring to detect spatial shifts in communities and population modeling

A Glass Polyalkenoate Cement Carrier for Bone Morphogenetic Proteins

This work considers a glass polyalkenoate cement (GPC)-based carrier for the effective delivery of bone morphogenetic proteins (BMPs) at an implantation site. A 0.12 CaO–0.04 SrO–0.36 ZnO–0.48 SiO2 based glass and poly(acrylic acid) (PAA, Mw 213,000) were employed for the fabrication of the GPC. The media used for the water source in the GPC reaction was altered to produce a series of GPCs. The GPC liquid media was either 100 % distilled water with additions of albumin at 0, 2, 5 and 8 wt% of the glass content, 100 % formulation buffer (IFB), and 100 % BMP (150 µg rhBMP-2/ml IFB). Rheological properties, compressive strength, ion release profiles and BMP release were evaluated. Working times (Tw) of the formulated GPCs significantly increased with the addition of 2 % albumin and remained constant with further increases in albumin content or IFB solutions. Setting time (Ts) experienced an increase with 2 and 5 % albumin content, but a decrease with 8 % albumin. Changing the liquid source to IFB containing 5 % albumin had no significant effect on Ts compared to the 8 % albumin-containing BT101. Replacing the albumin with IFB/BMP-2 did not significantly affect Tw. However, Ts increased for the BT101_BMP-2 containing GPCs, compared to all other samples. The compressive strength evaluated 1 day post cement mixing was not affected significantly by the incorporation of BMPs, but the ion release did increase from the cements, particularly for Zn and Sr. The GPCs released BMP after the first day, which decreased in content during the following 6 days. This study has proven that BMPs can be immobilized into GPCs and may result in novel materials for clinical applications

Farm Management Practices Used by Wheat Producers in the Western Great Plains: Estimating Their Productivity and Profitability

Changes in government farm programs and the introduction of new technology offer wheat producers in the western Great Plains a variety of management practices to alleviate biotic and agronomic constraints inherent in a wheat monoculture. Producers have adopted alternative tillage systems, crop diversification, and insect-resistant varieties in response to the hot, semiarid growing conditions and increased pest pressure. The objective of this study was to determine if those practices generated positive impacts on wheat yield and corresponding net returns. Panel data collected from a group of 141 producers over a four-year period (N = 564) were analyzed using econometric models. The most significant impacts were from crop diversification, which on average more than doubled returns from $29 to$69 per acre compared to a wheat monoculture. Pest-resistant varieties increased returns by 59%, from $32 to$51 per acre. The use of no-till reduced returns by an average of $13 per acre, but when combined with a modest level of crop diversity, returns approached breakeven. Stakeholders should aspire to increase the profitability of no-till to increase its adoption in this environmentally sensitive region