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Fort Pierce, FL, United States

Frias-Torres S.,Ocean Research and Conservation Association
ORYX | Year: 2013

The Goliath grouper Epinephelus itajara has been protected in the USA since 1990. In Florida commercial and recreational fishers consider the species a top predator of fish and lobster and advocate culling the grouper population as a solution to recover declining stocks. I examined the scientific evidence for and against culling the Goliath grouper, using commercial landing data from the National Marine Fisheries Service and the Florida Fish and Wildlife Conservation Commission (1950-2010), fisheries-independent diver-based surveys from the REEF Environmental Education Foundation (1993-2007), and published dietary and morphological studies. An analysis of the commercial extinction of the Goliath grouper in Florida indicates that its recovering population is not the cause of declining fish and lobster stocks. The recovering Goliath grouper population could provide ecological and socio-economic benefits: as top-down control on other lobster predators, in ecotourism, and as potential biocontrol of the invasive Indo-Pacific red lionfish Pterois volitans on Atlantic reefs. Copyright © Fauna & Flora International 2012. Source

Johnsen S.,Duke University | Marshall N.J.,University of Queensland | Widder E.A.,Ocean Research and Conservation Association
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2011

Because light in the pelagic environment is partially polarized, it has been suggested that the polarization sensitivity found in certain pelagic species may serve to enhance the contrast of their transparent zooplankton prey. We examined its potential during cruises in the Gulf of Mexico and Atlantic Ocean and at a field station on the Great Barrier Reef. First, we collected various species of transparent zooplankton and micronekton and photographed them between crossed polarizers. Many groups, particularly the cephalopods, pelagic snails, salps and ctenophores, were found to have ciliary, muscular or connective tissues with striking birefringence. In situ polarization imagery of the same species showed that, while the degree of underwater polarization was fairly high (approx. 30% in horizontal lines of sight), tissue birefringence played little to no role in increasing visibility. This is most likely due to the low radiance of the horizontal background light when compared with the downwelling irradiance. In fact, the dominant radiance and polarization contrasts are due to unpolarized downwelling light that has been scattered from the animal viewed against the darker and polarized horizontal background light. We show that relatively simple algorithms can use this negative polarization contrast to increase visibility substantially. © 2011 The Royal Society. Source

Cusick K.D.,U.S. Navy | Widder E.A.,Ocean Research and Conservation Association
Bulletin of Marine Science | Year: 2014

Bioluminescence in dinoflagellates is thought to function as a "burglar alarm," alerting visual predators to the presence of dinoflagellate grazers. However, many bioluminescent dinoflagellates, particularly those associated with harmful algal blooms (HABs), have a much lower bioluminescence capacity that seems less well-adapted for attracting the attention of distant secondary predators. The present study was motivated by a question regarding the impact of extreme differences in bioluminescence potential among dinoflagellates, particularly those with the capacity to form HABs. This study examined the function of bioluminescence in the bright emitter, Pyrocystis noctiluca (Murray, 1876), compared to the much dimmer HAB species, Lingulodinium polyedrum F. Stein (Stein 1883). The foraging efficiency of the nocturnal teleost, Apagon maculatus (Poey, 1860), was determined at a range of cell concentrations with both dinoflagellate species. At low cell concentrations of P. noctiluca, both the foraging efficiency and the orientation distance of the fish to the prey increased, indicating that bioluminescence functions as a burglar alarm. However, neither fish foraging efficiency nor orientation distance increased in the presence of luminescent L. polyedrum at low cell concentrations. At higher concentrations, the bioluminescence of L. polyedrum improved the foraging efficiency of the fish, but the orientation distance to the prey was no greater than with non-luminescent cells, indicating that at low cell concentrations, bioluminescence does not function as a burglar alarm in L. polyedrum. The role of bioluminescence as a possible aposematic signal in L. polyedrum is discussed, along with the implications for the role of bioluminescence in HAB dynamics. © 2011 Rosenstiel School of Marine and Atmospheric Science of the University of Miami. Source

Johnsen S.,Duke University | Frank T.M.,Nova Southeastern Oceanographic Center | Haddock S.H.D.,Monterey Bay Aquarium Research Institute | Widder E.A.,Ocean Research and Conservation Association | Messing C.G.,Nova Southeastern Oceanographic Center
Journal of Experimental Biology | Year: 2012

Bioluminescence is common and well studied in mesopelagic species. However, the extent of bioluminescence in benthic sites of similar depths is far less studied, although the relatively large eyes of benthic fish, crustaceans and cephalopods at bathyal depths suggest the presence of significant biogenic light. Using the Johnson-Sea-Link submersible, we collected numerous species of cnidarians, echinoderms, crustaceans, cephalopods and sponges, as well as one annelid from three sites in the northern Bahamas (500-1000 m depth). Using mechanical and chemical stimulation, we tested the collected species for light emission, and photographed and measured the spectra of the emitted light. In addition, in situ intensified video and still photos were taken of different benthic habitats. Surprisingly, bioluminescence in benthic animals at these sites was far less common than in mesopelagic animals from similar depths, with less than 20% of the collected species emitting light. Bioluminescent taxa comprised two species of anemone (Actinaria), a new genus and species of flabellate Parazoanthidae (formerly Gerardia sp.) (Zoanthidea), three sea pens (Pennatulacea), three bamboo corals (Alcyonacea), the chrysogorgiid coral Chrysogorgia desbonni (Alcyonacea), the caridean shrimp Parapandalus sp. and Heterocarpus ensifer (Decapoda), two holothuroids (Elasipodida and Aspidochirota) and the ophiuroid Ophiochiton ternispinus (Ophiurida). Except for the ophiuroid and the two shrimp, which emitted blue light (peak wavelengths 470 and 455 nm), all the species produced greener light than that measured in most mesopelagic taxa, with the emissions of the pennatulaceans being strongly shifted towards longer wavelengths. In situ observations suggested that bioluminescence associated with these sites was due primarily to light emitted by bioluminescent planktonic species as they struck filter feeders that extended into the water column. © 2012. Published by The Company of Biologists Ltd. Source

Widder E.A.,Ocean Research and Conservation Association
Science | Year: 2010

From bacteria to fish, a remarkable variety of marine life depends on bioluminescence (the chemical generation of light) for finding food, attracting mates, and evading predators. Disparate biochemical systems and diverse phylogenetic distribution patterns of light-emitting organisms highlight the ecological benefits of bioluminescence, with biochemical and genetic analyses providing new insights into the mechanisms of its evolution. The origins and functions of some bioluminescent systems, however, remain obscure. Here, I review recent advances in understanding bioluminescence in the ocean and highlight future research efforts that will unite molecular details with ecological and evolutionary relationships. Source

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