26 research outputs found

    The Effects of Siltation on Recruitment of Spiny Lobsters, Panulirus argus

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    Fewer juvenile pinry lobsters were found in areas of the Florida Keys where their primary habitat was heavily silted as compared with similar, less silted habitat. Several hypotheses explaining this relationship were tested, and the time-to-metamorphosis was compared for settling pueruli within silted and nonsilted algae stands. Limited postlarval settlement and avoidance of silted algal habitats by juveniles, probably accounts for the paucity of young lobsters in heavily silted sites. In addition, although juvenile lobsters are nonselective predators, lower prey availability in silted algae probably promotes transciency which, in turn, causes increased mortality by predation while juveniles are exposed

    Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago. 2. Lake, Marine, and Terrestrial Sediments

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    Part 1 of this study investigated evidence of biomass burning in global ice records, and here we continue to test the hypothesis that an impact event at the Younger Dryas boundary (YDB) caused an anomalously intense episode of biomass burning at ∼12.8 ka on a multicontinental scale (North and South America, Europe, and Asia). Quantitative analyses of charcoal and soot records from 152 lakes, marine cores, and terrestrial sequences reveal a major peak in biomass burning at the Younger Dryas (YD) onset that appears to be the highest during the latest Quaternary. For the Cretaceous-Tertiary boundary (K-Pg) impact event, concentrations of soot were previously utilized to estimate the global amount of biomass burned, and similar measurements suggest that wildfires at the YD onset rapidly consumed ∼10 million km2 of Earth’s surface, or ∼9% of Earth’s biomass, considerably more than for the K-Pg impact. Bayesian analyses and age regressions demonstrate that ages for YDB peaks in charcoal and soot across four continents are synchronous with the ages of an abundance peak in platinum in the Greenland Ice Sheet Project 2 (GISP2) ice core and of the YDB impact event (12,835–12,735 cal BP). Thus, existing evidence indicates that the YDB impact event caused an anomalously large episode of biomass burning, resulting in extensive atmospheric soot/dust loading that triggered an “impact winter.” This, in turn, triggered abrupt YD cooling and other climate changes, reinforced by climatic feedback mechanisms, including Arctic sea ice expansion, rerouting of North American continental runoff, and subsequent ocean circulation changes

    Survival and Development of Horseshoe Crab (Limulus polyphemus) Embryos and Larvae in Hypersaline Conditions

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    Volume: 206Start Page: 87End Page: 9

    Spatial patterns in the ovigerous Callinectes sapidus spawning migration: results from a coupled behavioral-physical model

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    Ovigerous blue crabs Callinectes sapidus use ebb-tide transport (ETT), a vertical migratory behavior in which crabs ascend into the water column during ebb tides, to migrate from estuarine adult habitats to coastal larval release locations. We have developed a detailed behavioral model of ovigerous blue crab ETT from previous laboratory and field studies and coupled this model to a hydrodynamic model of the Beaufort Inlet region of North Carolina. We have simulated the trajectories of migratory ovigerous crabs in the region and determined spatial patterns in migratory success, migratory speeds, the residence times of crabs in different regions of the estuary, and potential larval-release locations. Highly active crabs can start their migration from almost anywhere in the estuary and reach suitable larval-release locations within a typical 4 d migratory period, whereas crabs with lower activity levels can only reach suitable larval-release locations if they start their migration in the lower-to-mid estuary. Migratory speeds in the estuary range from 8 km d-1. Crabs with lower activity levels are resident in the mid-to-upper estuary for relatively long periods of time, whereas highly active crabs are resident in the lower estuary and coastal ocean for most of the migratory period. Larval release is predicted to occur throughout the estuary and in the coastal ocean within -5 km of Beaufort Inlet. Fisheries managers can use these spatial patterns to determine management strategies (e.g. spatial closures to fishing) that will protect migratory blue crab spawning stock in tidal regions effectively
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