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Full-Text Articles in Life Sciences

Increased Reactive Oxygen Intermediate Production By Hemocytes Withdrawn From Crassostrea Virginica Infected With Perkinsus Marinus, Rs Anderson, Ky Paynter, Em Burreson Nov 1992

Increased Reactive Oxygen Intermediate Production By Hemocytes Withdrawn From Crassostrea Virginica Infected With Perkinsus Marinus, Rs Anderson, Ky Paynter, Em Burreson

VIMS Articles

Perkinsus marinus is a protozoan parasite responsible for a major infectious disease of the Eastern oyster, Crassostrea virginica. Nonspecific immunity was assayed in oysters with known intensities of infection so that the physiological responses of the host elicited by the parasite could be better understood. This report describes the capacity of hemocytes to generate reactive oxygen intermediates during the progression of the disease. The hemocytes constitute the major internal defense effector system of oysters, and cytotoxic oxygen species are thought to play central roles in antimicrobial activities of hemocytes and other phagocytic cells. Production of oxyradicals by both resting and ...


A Rapid Chromatographic Method For Recovery Of 15no2- And No3- Produced By Nitrification In Aqueous Samples, H Kator, Lj Morris, Rl Wetzel Jun 1992

A Rapid Chromatographic Method For Recovery Of 15no2- And No3- Produced By Nitrification In Aqueous Samples, H Kator, Lj Morris, Rl Wetzel

VIMS Articles

The sensitivity and comparative simplicity of N-15 stable isotopic tracer techniques has been used to quantify rates of nitrification in aquatic systems. However, the most commonly used method for recovery of inorganic oxidized nitrogen compounds from aqueous samples, which is based on liquid-liquid partitioning, is time consuming and contamination prone. We describe a solid-phase rapid chromatographic method for recovery of (NO2-)-N-15 and NO3- produced by nitrification in aqueous samples. Compared to liquid-liquid partitioning, the advantages are significantly reduced processing time and reduced potential for contamination. Typical results are presented for the tidal, freshwater reaches of the James River estuary.


Shelter Selection By Spiny Lobster Under Variable Predation Risk, Social Conditions, And Shelter Size, Db Eggleston, Rom Lipcius Jun 1992

Shelter Selection By Spiny Lobster Under Variable Predation Risk, Social Conditions, And Shelter Size, Db Eggleston, Rom Lipcius

VIMS Articles

Shelter use patterns of den dwelling Caribbean spiny lobster, Panulirus argus, appear to be regulated by predation risk. The risk of predation may be modified by (1) social structure, which alters the effectiveness of communal defense, and (2) the scaling between lobster size and shelter size, which enhances the protective capacity of the den. These hypotheses were tested with field enclosure experiments using artificial lobster shelters, which examined the effects of predation risk (i.e., presence or absence of a major predator, the nurse shark Ginglyostoma cirratum), spiny lobster size, social condition (i.e., presence or absence of conspecifics), and ...


Effects Of Hypoxia And Anoxia On Larval Settlement, Juvenile Growth, And Juvenile Survival Of The Oyster Crassostrea Virginica, Sm Baker, Roger L. Mann Apr 1992

Effects Of Hypoxia And Anoxia On Larval Settlement, Juvenile Growth, And Juvenile Survival Of The Oyster Crassostrea Virginica, Sm Baker, Roger L. Mann

VIMS Articles

The effects of hypoxia and anoxia on oyster (Crassostrea virginica) larval settlement, juvenile growth, and juvenile survival were studied. Settlement was reduced significantly (P < 0.05) in hypoxic treatments, as compared to normoxic treatments , and almost no settlement took place in anoxic treatments. After 96 h, 38% and 4% of the larvae placed in hypoxic and anoxic treatments had settled, while 79% settled in normoxic treatments. In the first 144 h after settlement, juveniles in hypoxic treatments grew one third as much as those in normoxic treatments, while juveniles in anoxic treatments did not grow at all. Median mortality times of recently settled juveniles in hypoxic and anoxic treatments were 131 h and 84 h, respectively. We conclude that hypoxic and anoxic waters have potentially detrimental effects on oyster settlement and recruitment.


Oligomer Composition And Oxygen Binding Of The Hemocyanin Of The Blue Crab Callinectes Sapidus, Cp Mangum, J Greaves, Js Rainer Mar 1992

Oligomer Composition And Oxygen Binding Of The Hemocyanin Of The Blue Crab Callinectes Sapidus, Cp Mangum, J Greaves, Js Rainer

VIMS Articles

In the blue crab, the ratio of hexamers to dodecamers of the O2 carrier hemocyanin varies in natural populations. Isolated dodecamers have a lower O2 affinity and greater cooperativity than isolated hexamers. The difference in O2 binding can also be resolved in native mixtures that differ in polymer composition. A high content of dodecamers in native mixtures is, in fact, correlated with the presence of an invariant polypeptide chain that is believed to link two hexamers to form dodecamers. On the other hand, the content of a variable chain that has been postulated to play a role in hexamer pairing ...


Measurement Of Marine Picoplankton Cell-Size By Using A Cooled, Charge-Coupled Device Camera With Image-Analyzed Fluorescence Microscopy, Cl Viles, Me Sieracki Feb 1992

Measurement Of Marine Picoplankton Cell-Size By Using A Cooled, Charge-Coupled Device Camera With Image-Analyzed Fluorescence Microscopy, Cl Viles, Me Sieracki

VIMS Articles

Accurate measurement of the biomass and size distribution of picoplankton cells (0.2 to 2.0-mu-m) is paramount in characterizing their contribution to the oceanic food web and global biogeochemical cycling. Image-analyzed fluorescence microscopy, usually based on video camera technology, allows detailed measurements of individual cells to be taken. The application of an imaging system employing a cooled, slow-scan charge-coupled device (CCD) camera to automated counting and sizing of individual picoplankton cells from natural marine samples is described. A slow-scan CCD-based camera was compared to a video camera and was superior for detecting and sizing very small, dim particles such ...


Annular Growth Layers In Juvenile Loggerhead Turtles (Caretta-Caretta), Rc Klinger, Ja Musick Jan 1992

Annular Growth Layers In Juvenile Loggerhead Turtles (Caretta-Caretta), Rc Klinger, Ja Musick

VIMS Articles

Juvenile loggerhead turtles (Caretta caretta) were tagged with tetracycline to establish a chronology for deposition of periosteal bone growth layers. Eight recaptures, encompassing intervals of 1 to 3 years, were used to demonstrate that these growth layers were typically deposited on an annual basis. However, the number of scorable growth layers represents an underestimate of true age because earlier growth layers are obscured by expansion of the medullary cavity during growth. The number of absorbed growth layers was extrapolated from calculations based on juvenile bone growth patterns. Most (83%) of these corrected age estimates for juvenile loggerheads, 40 to 80 ...


Artificial Shelters And Survival Of Juvenile Caribbean Spiny Lobster Panulirus-Argus - Spatial, Habitat, And Lobster Size Effects, David B. Eggleston, Rom Lipcius, Dl Miller Jan 1992

Artificial Shelters And Survival Of Juvenile Caribbean Spiny Lobster Panulirus-Argus - Spatial, Habitat, And Lobster Size Effects, David B. Eggleston, Rom Lipcius, Dl Miller

VIMS Articles

A principal mechanism underlying a production hypothesis that artifical reefs increase environmental carrying capacity and eventually the biomass of reef-associated organisms is that these structures reduce predation on reef residents. We tested this predation mechanism with a series of field experiments at two sites (inner-bay sand-seagrass flat, and outer-bay seagrass bed adjacent to coral reefs) in Bahia de la Ascension, Mexico. We examined survival of two size-classes of juvenile Caribbean spiny lobster Panulirus argus tethered in seagrass beds with and without access to artificial lobster shelters, and at different distances from the shelters. The artificial shelters were concrete structures (casitas ...


A Genetic-Analysis Of Weakfish Cynoscion-Regalis Stock Structure Along The Mid-Atlantic Coast, John Graves, Jan Mcdowell, M. Lisa Jones Jan 1992

A Genetic-Analysis Of Weakfish Cynoscion-Regalis Stock Structure Along The Mid-Atlantic Coast, John Graves, Jan Mcdowell, M. Lisa Jones

VIMS Articles

To investigate the genetic basis of stock structure of the weakfish Cynoscion regalis, a total of 370 individuals was collected from four geographic sites along the mid-Atlantic coast of the United States over a period of 4 years. Restriction fragment length polymorphism (RFLP) analysis of weakfish mitochondrial DNA, employing either 6 or 13 restriction endonucleases, demonstrated a low level of intraspecific mtDNA variation, with a mean nucleotide sequence divergence of 0.13% for the pooled samples. The common mtDNA genotype occurred at a frequency of 0.91-0.96 in all samples, and no significant heterogeneity was found among samples in ...


Density-Dependent Predation By Blue Crabs Upon Infaunal Clam Species With Contrasting Distribution And Abundance Patterns, Db Eggleston, Rom Lipcius, Ah Hines Jan 1992

Density-Dependent Predation By Blue Crabs Upon Infaunal Clam Species With Contrasting Distribution And Abundance Patterns, Db Eggleston, Rom Lipcius, Ah Hines

VIMS Articles

Adult infaunal clams (Macoma balthica) persist at low densities in sandy and muddy habitats in Chesapeake Bay, USA, despite intense predation by blue crabs Callinectes sapidus; another infaunal soft-shelled clam (Mya arenaria) only persists in sandy habitats. We hypothesized that the persistence of M. balthica and M. arenaria in certain habitats was due to blue crabs exhibiting a type III (sigmoid) functional response whereby the risk of mortality is reduced at low clam densities. Laboratory experiments assessed functional responses (prey consumption predator-1 as a function of prey density) of large male blue crabs to 6 densities of M. balthica as ...


Relationship Of Habitat And Spatial Scale With Physiological State And Settlement Of Blue Crab Postlarvae In Chesapeake Bay, Ks Metcalf, Rom Lipcius Jan 1992

Relationship Of Habitat And Spatial Scale With Physiological State And Settlement Of Blue Crab Postlarvae In Chesapeake Bay, Ks Metcalf, Rom Lipcius

VIMS Articles

Physiological state (molt stage) of planktonic and benthic blue crab (Callinectes sapidus) postlarvae (megalopae) was quantified within and outside Chesapeake Bay at various spatial scales. Physiological state of planktonic megalopae advanced significantly from the continental shelf off the Chesapeake Bay mouth, through the bay mainstem, and into upriver stations in the York River, a tributary of Chesapeake Bay. These results imply that settlement and metamorphosis of blue crab megalopae is dependent on location relative to the shelf. The physiological evidence supports the export-reinvasion theory of blue crab recruitment and is inconsistent with a larval retention hypothesis. In the tributary, benthic ...


Comparison Of Condition Index (K) Of Spot (Leiostomus Xanthurus) From The Elizabeth And York Rivers, Virginia, Kinloch Nelson, Herbert M. Austin Jan 1992

Comparison Of Condition Index (K) Of Spot (Leiostomus Xanthurus) From The Elizabeth And York Rivers, Virginia, Kinloch Nelson, Herbert M. Austin

VIMS Articles

Condition Index (K) was measured on spot, Leiostomus xanthums from the York ( control) and Elizabeth rivers (Experimental-polluted) in 1983-1985. Condition indices for the two populations were regressed against seasonal temperature at the time of capture. Between 6.0 and 19.0 C the Condition Index of the two populations rises in synchrony. Above 19 .0 C the Elizabeth River Condition Index continues to rise, and the York begins to drop. Above 26 C the York drops to levels approaching those of winter, and the Elizabeth continues to rise to the highest levels measured. It is hypothesized that this disparity is ...


Index Of Papers Published In The Journal Of Shellfish Research Volume 1-10 (1981-1991), Michael Castagna, Nancy Lewis, Charles Mcfadden, Mary Gibbons Jan 1992

Index Of Papers Published In The Journal Of Shellfish Research Volume 1-10 (1981-1991), Michael Castagna, Nancy Lewis, Charles Mcfadden, Mary Gibbons

VIMS Articles

No abstract provided.


Stock Structure Of The Bluefish Pomatomus-Saltatrix Along The Mid-Atlantic Coast, John Graves, Jan Mcdowell, Ana M. Beardsley, Daniel Scoles Jan 1992

Stock Structure Of The Bluefish Pomatomus-Saltatrix Along The Mid-Atlantic Coast, John Graves, Jan Mcdowell, Ana M. Beardsley, Daniel Scoles

VIMS Articles

Restriction-fragment length polymorphism analysis of mitochondrial DNA (mtDNA) was used to investigate the genetic basis of stock structure of the bluefish Pomatomus saltatrix along the U. S. mid-Atlantic coast, and to determine the degree of genetic differentiation between mid-Atlantic bluefish and Australian conspecifics. A total of 472 young-of-the-year (YOY) and yearling bluefish collected in New Jersey, Virginia, and North Carolina over a period of 3 years, and 19 YOY bluefish collected in New South Wales, Australia were analyzed with 9 informative restriction endonucleases. Despite considerable mtDNA variation within samples of U.S. mid-Atlantic bluefish, no significant genetic differentiation was detected ...


Age, Growth, And Reproduction Of The Goosefish Lophius-Americanus (Pisces, Lophiiformes), Michael P. Armstrong, John Musick, James A. Colvocoresses Jan 1992

Age, Growth, And Reproduction Of The Goosefish Lophius-Americanus (Pisces, Lophiiformes), Michael P. Armstrong, John Musick, James A. Colvocoresses

VIMS Articles

Age, growth, and reproduction were studied in goosefish Lophius americanus collected from National Marine Fisheries Service groundfish surveys and commercial fishing cruises between Georges Bank and Cape Hatteras in the western North Atlantic. Age and growth of L. americanus were determined from vertebral annuli, which became visible at the edge of the vertebral centra in May. Maximum ages of males and females were 9 and 11 years, respectively. Males appeared to experience higher mortality than females in the older age-classes. Von Bertalanffy growth curves calculated for males and females had excellent agreement with back-calculated lengths. The growth rate of L ...


A Comparison Of Methods For Calculating Condition Index In Eastern Oysters Crassostrea Virginica (Gmelin, 1791), Roger L. Mann Jan 1992

A Comparison Of Methods For Calculating Condition Index In Eastern Oysters Crassostrea Virginica (Gmelin, 1791), Roger L. Mann

VIMS Articles

A number of techniques have been reported to estimate condition index in oysters and other bivalve molluscs. We report and compare condition index, estimated by three different methods, for oysters collected from a single reef in the James River, Virginia over a four week period in the summer of 1987. Two indices express condition as a ratio of dry meat weight to shell cavity volume, but differ in methods of estimating shell cavity volume. A third method expresses condition as a ratio of dry meat weight to dry shell weight. Within the size range 36-96 mm length there is no ...


Temporal And Spatial Changes In Fecundity Of Eastern Oysters, Crassostrea Virginica (Gmelin, 1791) In The James River, Virginia, Carrollyn Cox, Roger L. Mann Jan 1992

Temporal And Spatial Changes In Fecundity Of Eastern Oysters, Crassostrea Virginica (Gmelin, 1791) In The James River, Virginia, Carrollyn Cox, Roger L. Mann

VIMS Articles

A~u1t Crass~strea virgi.nic~ ~Gmelin) were examined during the reproductive season of 1986 to determine temporal and spatial vanation m fecundity among md!Vldual female oysters from four reefs in the James River, Virginia. Sex ratio and oyster abu.ndance were. ~so determined to :acilitate ~s~imation of total reproductive output of oyster assemblages. Fecundity was highly vanable, both w1thm and among locations. Vanation was attributed to differences in oyster size, asynchrony and variation in time since pri~r spawning, prevalence of parasites (especially Haplosporidium nelsoni (MSX) and Perkinsus marinus) and differing salinity regimes.