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ABSTRACT: The population dynamics and life history characteristics of Callinectes similis and C. sapidus in the Mobile Bay-Mississippi Sound estuarine system of the northern Gulf of Mexico were studied. We report that C. similis is numerically dominant in open-bays, while C. sapidus is more abundant in shallow salt marshes. Juvenile C. similis recruit into both open-bays and salt marshes, but juvenile C. sapidus primarily recruit into shallow salt marshes. Sex ratios of C. similis and C. sapidus were generally skewed towards higher proportions of males than females. Callinectes similis appears to have a life cycle similar to that of C. sapidus. Egg-carrying C. similis migrate to higher salinity waters and presumably release larvae to nearshore shelf waters; following development, the larvae re-invade estuaries as megalopae. Juvenile C. similis grow more slowly than C. sapidus. This may be attributable to reduced feeding rates. Marked differences in fecundity and reproductive effort were found between these species. Callinectes similis and C. sapidus, respectively, produced 2.4–5.5 times 105 and 2.1–3.2 times 106 eggs and invested 24–49 and 171–372 kJ per brood. Rhizocephalan barnacle infestation by Loxothylacus texanus was encountered in C. sapidus, while sympatric C. similis were free of this rhizocephalan parasite.
Marine Ecology 05/2008; 14(3):239 - 257. · 1.84 Impact Factor
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06/2004;
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ABSTRACT: The present study investigated aspects of the antifoulant properties of three sympatric species of ascidians found in seagrass habitats of the Gulf of Mexico, Southern Atlantic Ocean, and Caribbean. Field observations in Saint Joseph Bay, Florida indicate that all three species are common and that the tunic of the solitary ascidian Molgula occidentalis is often heavily fouled, while the outer surfaces of both the colonial ascidians Amaroucium stellatum and Botryllus planus are free of fouling organisms. Antifoulant activities of a suite of increasing hydrophilic organic extracts prepared from the tunic of M. occidentalis and whole colonies of A. stellatum and B. planus were measured using both sympatric microbial (bacteria) and macroinvertebrate (cyprid larvae of Balanus amphitrite) fouling organisms in laboratory bioassays. In addition, field antifoulant assays were conducted by combining organic extracts with controlled-release resin and subsequently coating this material on to acrylic rods deployed in the field for a 72 h period. Extracts of the tunic of M. occidentalis generally did not inhibit bacterial growth. The exception was the methanol extract, which inhibited growth in one of the six marine bacteria tested. Moreover, only the highest concentrations of hexane and methanol tunic extracts tested prevented attachment of cyprid larvae. Field assays revealed no antifoulant activity on rods coated with resin containing extracts of M. occidentalis. Inhibition of both microbial growth and cyprid settlement were much more pronounced in whole-organism extracts of the two colonial ascidians. Most potent were the aqueous methanol extracts of colonies of B. planus and A. stellatum which inhibited growth in five of the six marine bacteria tested. In addition, hydrophilic and lipophilic extracts of the colonial ascidians significantly inhibited attachment of cyprid larvae, in many instances across a wide range of extract concentrations. Field antifoulant assays indicated that extracts of both colonial ascidians inhibited settlement of bryozoans and barnacles. The findings indicate that the colonial ascidians B. planus and A. stellatum possess chemical antifoulant properties. In contrast, the solitary ascidian M. occidentalis appears to either tolerate fouling or possess other non-chemical mechanisms to cope with the risks associated with epibiont overgrowth.
Biofouling 09/2003; 19(4):235-45. · 4.43 Impact Factor
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04/2002;
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ABSTRACT: Aqueous extracts of the mantle tissues of the opisthobranchs Austrodoris kerguelensis and Tritoniella belli and the lamellarid gastropod Marseniopsis mollis were cytotoxic to the sperm of the antarctic sea urchin Sterechinus neumayeri, and caused behavioral responses (sustained terminal sensory tube-feet retractions) in five species of antarctic sea stars. Pieces of mantle tissue of all three species were noxious to two species of antarctic fish. Primary body components (mantle, foot, viscera) of the three gastropod species contained high levels (% dry wt) of NaOH-insoluble protein (40–59%), moderate levels of NaOH-soluble protein (7–25%) and lipid (6–18%), and low levels of carbohydrate (< 1%).="" the="" energetic="" composition="" of="" the="" tissues="" reflected="" their="" organic="" make-up,="" with="" most="" energy="" (11–17="">–1 dry wt) associated with protein. Total energy contents of representative adult individuals were 192,26 and 69 kJ for A. kerguelensis (93 g wet wt), T. belli (22 g wet wt) and M. mollis (114 g wet wt), respectively. Although these sluggish gastropods lack an external shell and are nutrient-and energy-rich and therefore high quality prey, like many of their temperate and tropical counterparts, they appear to be protected by chemicals.
Polar Biology 02/1992; 11(8):623-629. · 1.66 Impact Factor
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ABSTRACT: The biochemical and energetic composition, population biology (size-weight relationship, abundance and size-frequency distribution) and chemical defense of the antarctic ascidian Cnemidocarpa verrucosa Lesson was investigated at McMurdo Sound, Antarctica, during the austral summer of 1989. The organic content (% organic material · g−1 dry tissue wt) of individual body components (tunic, body wall, endocarps, intestines, mature ovitestes and branchial basket) was generally high, with values ranging from 44.5% in the endocarps to 83.9% in the gonads. Most of this material was in the form of NaOH-soluble and insoluble protein. Tissue energy values ranged from 15.1 (tunic) to 22.4 (gonad) kJ · g−1 dry wt. Body height (cm) was positively related to body weight (g dry wt) by an exponential function. A representative individual (14 cm height, 550 g wet wt) contained a total of 493 kJ with most (75%) of this energy attributable to the body wall and tunic. The gonadal index [(kJ ovitestes · total kJ−1) x 100] for sexually mature individuals collected in November was 17.2 ± 4.7 (n = 6). Population densities of C. verrucosa at depths of 20–30 m were 0.4 ind · m−2 at a site 3 km north of McMurdo Station. Energetic densities were estimated to be 197 kJ · m−2. Size-frequency analysis revealed four modal peaks that probably represent distinct age cohorts, and may indicate predictable, annual recruitment events. Bioassays revealed that the tunic was noxious to sympatric pelagic and benthic fish, as well as an allopatric model fish. However, aqueous tunic extracts did not cause mortality in sea urchin sperm indicating the noxious compound(s) is not cytotoxic. pH values for body components were weakly acidic or neutral (5.86–6.93). Mature ovitestes were rejected by sympatric pelagic fish suggesting that gametes may be chemically defended. Although this common antarctic ascidian represents a significant resource of materials and energy, its tunic is tough and noxious, and probably provides an effective means of defense against potential predators.
Journal of Experimental Marine Biology and Ecology.
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ABSTRACT: The feeding deterrent effects of echinoderm body-wall tissues and ethanolic extracts containing mid-polarity compounds were evaluated utilizing generalist fish and crabs as model predators. The body-wall tissues of the echinoderms examined ranged 10-fold from 0.9–9.4 mm in thickness, and four and a half-fold in level of mineralization (17.8–82.7% ash content). Holothuroids had the thickest body-wall tissues and contained the lowest levels of mineralization in their body-walls. Crinoids and ophiuroids had high levels of mineralization in their arms. Asteroid body-wall tissues varied the most in thickness and ash content (0.9–3.9 mm in thickness and 29.2–55.5% in ash content). Body-wall tissues of 19 species of echinoderms were tested for their feeding deterrent properties against the marine fishes Lagodon rhomboides (Linnaeus) and Cyprinodon variegatus (Lacepede), as well as the decapod crustacean Libinia emarginata (Leach). Equivalent sized pieces of fresh body-wall tissue of 16 species of echinoderms caused observable feeding deterrence responses in at least two of the three model predators. There was no significant correlation between body-wall thickness or percent ash and its palatability to any of the three model predators. Agar pellets containing ethanolic body-wall extracts of 12 of 18 echinoderm species caused observable feeding deterrence responses in the fish L. rhomboides. In similar experiments with the arrow crab Stenorhyncus seticornis (Herbst), using carrageenan fish-meal blocks as food models, no differences in consumption of control fish-meal and experimental body-wall extract blocks were detected. Our findings indicate that invertebrate and vertebrate predators may respond quite differently to echinoderm body-wall extracts.
Journal of Experimental Marine Biology and Ecology.
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ABSTRACT: The ethanolic body-wall extracts of 16 species of echinoderms from 16 genera were screened for their ability to affect the attachment of the marine bacteria Deleya marina (Baumann) and Alteromonas luteo-violacea (Gauthier). Body-wall extracts were tested at concentrations which mimic mean natural tissue concentration, 3.0 mg/ml seawater, and four half-log dilutions of this initial concentration. The extracts of three echinoderm species caused significant inhibition of bacterial attachment, while extracts of eight species caused significant enhancement of attachment. The body-wall extract of the asteroid Goniaster tesselatus (Lamarck) displayed the most potent antimicrobial activity, completely inhibiting attachment of both bacterial species at a concentration of 3.0 mg/ml seawater. The ethanolic extracts of 20 echinoderm species were also tested at a similar range of concentrations for their ability to affect the settlement of cyprid larvae of the barnacle Balanus amphitrite (Darwin), and coronate larvae of the bryozoan Bugula neritina (Linné). All echinoderm extracts inhibited settlement of both barnacle and bryozoan larvae at the highest concentration tested (3.0 mg/ml seawater). Eleven of the 20 echinoderms tested (13 asteroids, 3 holothuroids, 3 ophiuroids and a crinoid) had body-wall extracts that inhibited settlement of competent barnacle and bryozoan larvae at concentrations as low as 0.12 mg/ml seawater. These extracted echinoderm compounds may function as non-toxic or toxic antifoulants, and to promote bacterial surface colonization, which could be valuable to the organisms disease resistance.
Journal of Experimental Marine Biology and Ecology.
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ABSTRACT: Organic extracts from the antarctic soft corals Alcyonium paessleri May and Gersemia antarctica Kukenthal exhibited antimicrobial and antifoulant activity. A third antarctic soft coral, the stoloniferan Clavularia frankliniana Roule, exhibited no such bioactivity. Marine bacterial attachment was inhibited in the presence of chloroform and aqueous methanol extracts of A. paessleri and G. antarctica, but not in the presence of solvent controls. Similarly, inhibition of microbial growth in three sympatric species of antarctic marine bacteria occurred in response to aqueous methanol extracts of these two soft corals, but not to the controls. Antifoulant activity of chloroform extracts of A. paessleri and G. antarctica was detected in a month-long field assay measuring inhibition of benthic diatom settlement. Observed invertebrate recruitment rates were too low to allow an evaluation of antifoulant bioactivity. Laboratory growth experiments, employing the antarctic diatom Navicula sp. and larvae of the antarctic sea urchin Sterechinus neumayeri Meissner, confirmed the presence of growth-inhibiting metabolites in the soft corals A. paessleri and G. antarctica. These results suggest that both A. paessleri and G. antarctica, which do not appear to be fouled in the field, possess bioactive compounds with antifoulant activity. In contrast, C. frankliniana, which is often heavily fouled, appears to lack antifouling compounds.
Journal of Experimental Marine Biology and Ecology.
