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Full-Text Articles in Life Sciences
Survival Of Juvenile Caribbean Spiny Lobster: Effects Of Shelter Size, Geographic Location And Conspecific Abundance, Jd Mintz, Rom Lipcius, Db Eggleson, Ms Seebo
Survival Of Juvenile Caribbean Spiny Lobster: Effects Of Shelter Size, Geographic Location And Conspecific Abundance, Jd Mintz, Rom Lipcius, Db Eggleson, Ms Seebo
VIMS Articles
The Caribbean spiny lobster Panulirus argus seeks structured shelter throughout its benthic phase, often forming aggregations within shelters. Casitas - concrete, low-relief, artificial shelters - are effective in aggregating lobsters, and are used to harvest spiny lobster in the Caribbean. However, casitas may also enhance populations of P. argus, by providing shelter from predation. In this study we examined the effects of various shelter features upon the survival of juvenile P. argus. Juvenile lobsters were tethered at several artificial shelter treatments in Florida Bay, Florida, USA, to test the efficacy of casitas as refuge from predation. Survival of juveniles was …
Technical Efficiency, Biological Considerations, And Management And Regulation Of The Sea-Scallop, Placopecten-Magellanicus (Gmelin, 1791) Fishery, James E. Kirkley, William D. Dupaul
Technical Efficiency, Biological Considerations, And Management And Regulation Of The Sea-Scallop, Placopecten-Magellanicus (Gmelin, 1791) Fishery, James E. Kirkley, William D. Dupaul
VIMS Articles
Achieving social and economic efficiency in a fishery requires that production be technically efficient. Yet, technical efficiency (TE) is rarely examined for a fishery. By the use of detailed trip-level data and information about resource conditions obtained from routine sampling, a stochastic frontier production model relating landings to days at sea, crew size, and resource conditions is specified and estimated for 10 Mid-Atlantic sea scallop (Placopecten magellanicus) dredge vessels. TE is shown to depend partly on the mix of controllable inputs such as days at sea and crew size but possibly more on uncontrollable factors such as resource conditions and …
Reproductive Activity Of Oysters, Crassostrea-Virginica (Gmelin, 1791) In The James River, Virginia, During 1987-1988, Roger L. Mann, Julia S. Rainer, Reinaldo Morales-Alamo
Reproductive Activity Of Oysters, Crassostrea-Virginica (Gmelin, 1791) In The James River, Virginia, During 1987-1988, Roger L. Mann, Julia S. Rainer, Reinaldo Morales-Alamo
VIMS Articles
Reproductive activity in oysters, Crassostrea virginica Gmelin, in the James River, Virginia, was examined for 1987 from weekly estimates for fecundity and egg viability in oysters collected from Wreck Shoal, and for 1988 from weekly estimates of fecundity, egg viability, gonad volume fraction, gonad thickness, and mean egg size in oysters collected from Horsehead Reef. Maximum and mean fecundity values from Wreck Shoal oysters were higher than from Horsehead oysters. No relationship was evident between fecundity and egg viability at Horsehead Reef. A strong temporal relationship was observed between egg viability and peak oyster settlement in the James in both …
Description Of Metamorphic Phases In The Oyster Crassostrea Virginica And Effects Of Hypoxia On Metamorphosis, Sm Baker, Roger L. Mann
Description Of Metamorphic Phases In The Oyster Crassostrea Virginica And Effects Of Hypoxia On Metamorphosis, Sm Baker, Roger L. Mann
VIMS Articles
Four phases of metamorphosis in the eastern oyster Crassostrea virginica were characterized:'settlers' have attached to the substrate but retain larval characteristics; metamorphosis and degeneration of the velum has begun in 'prodissoconch postlarvae'; in 'dissoconch postlarvae' shell growth beyond the prodissoconch has begun but the foot persists; and 'juveniles' have lost all larval organs and metamorphosis is complete. These phases were used in examining the metamorphic process during and following continuous and short-term exposures to hypoxia (1.5 mg O-2 l(-1), 20 % of air saturation) and microxia (< 0.07 mg O(2)l(-1), < 1 % of air saturation). We observed no abnormal development in the oysters, but development was delayed following 3 d exposures to hypoxia, and 2 and 3 d exposures to microxia. Under continuous exposure to microxia, oysters did not develop to the dissoconch postlarva or juvenile phases. Approximately 50 % of the control oysters died within the 2 wk period following settlement. Morality was virtually confined to the settler and prodissoconch postlarva phases. Short-term exposures to hypoxia (1 to 3 d) and microxia (1 d) had little effect on the median mortality time or final total mortality, compared to controls. Microxic treatments longer than 1 d did affect mortality and oysters continuously exposed to microxia had a median mortality time of 87 h. Short-term exposures to low oxygen did not have permanent effects on post-settlement growth rates. Oysters exposed to microxic treatments, however, appeared to have slower growth rates during the exposure period. We conclude that low oxygen conditions, in particular those that are microxic and last longer than 24 h, have detrimental effects on the development, growth, and mortality of post settlement oysters.