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Full-Text Articles in Life Sciences

Color Image-Analyzed Fluorescence Microscopy: A New Tool For Marine Microbial Ecology, Ml Sieracki, Cl Viles Nov 1990

Color Image-Analyzed Fluorescence Microscopy: A New Tool For Marine Microbial Ecology, Ml Sieracki, Cl Viles

VIMS Articles

BACTERIA, cyanobacteria, protozoa and small eukaryotic phytoplankton are now known to be funda- mental components of marine planktonic ecosystems (Azam et al., 1983; Sieburth, 1984). These organisms have high potential growth rates, are efficient convert- ers of material and energy, and usually constitute most of the plankton biomass (Davis et al., 1985; Fuhrman et al., 1989). Their different trophic levels are often closely coupled. These characteristics require that experimental and sampling designs for studying the microbial populations incorporate appropriate (i.e., small) temporal and spatial scales. The corollary to this is that large numbers of samples must be taken. If ...


Biochemical Genetics Of Southern California Basses Of The Genus Paralabrax - Specific Identification Of Fresh And Ethanol-Preserved Individual Eggs And Early Larvae, John Graves, Michelle J. Curtis, Paul A. Oeth, Robin S. Waples Jan 1990

Biochemical Genetics Of Southern California Basses Of The Genus Paralabrax - Specific Identification Of Fresh And Ethanol-Preserved Individual Eggs And Early Larvae, John Graves, Michelle J. Curtis, Paul A. Oeth, Robin S. Waples

VIMS Articles

No abstract provided.


Settlement Of Oysters, Crassostrea Virginica (Gmelin, 1791), On Oyster Shell, Expanded Shale And Tire Chips In The James River, Virginia, Roger L. Mann, Bruce J. Barber, James P. Whitcomb, Kenneth S. Walker Jan 1990

Settlement Of Oysters, Crassostrea Virginica (Gmelin, 1791), On Oyster Shell, Expanded Shale And Tire Chips In The James River, Virginia, Roger L. Mann, Bruce J. Barber, James P. Whitcomb, Kenneth S. Walker

VIMS Articles

The effectiveness of oyster shell, expanded shale, and tire chips as substrates for settlement of oysters, Crassostrea virgi11ica (Gmelin), was compared at four locations in the James River, Virginia, over three two-week time intervals in August and September, 1988. Only differences between substrate were significant (P < 0.001). Over all locations and time intervals, a significantly higher (P < 0.001) proportion of total oyster settlement occurred on oyster shell (63.8%) than on either tire chips (22.1 %) or expanded shale (14.2%).


Utilization Of A Seagrass Meadow And Tidal Marsh Creek By Blue Crabs Callinectes-Sapidus Ii. Spatial And Temporal Patterns Of Molting, Ch Ryer, J Van Montfrans, Rj Orth Jan 1990

Utilization Of A Seagrass Meadow And Tidal Marsh Creek By Blue Crabs Callinectes-Sapidus Ii. Spatial And Temporal Patterns Of Molting, Ch Ryer, J Van Montfrans, Rj Orth

VIMS Articles

Blue crabs were collected weekly from a lower Chesapeake Bay seagrass meadow and adjacent tidal marsh creek over 2 months (July-August 1987) and molt staged. Molting activity, determined from a total of I ,220 crabs, was greater in the grassbed than in the marsh creek, and greater for small crabs and females. The difference between the two habitats in molting activity decreased from the first to the second month of sampling, possibly in response to seasonal decline in seagrass biomass. The proportion of small (<70 mm) females in both habitats was greatest on full moons. There was a lunar rhythm of molting activity by large crabs (2:70 mm), with peak molting activity on fuIl moons. SmaIl crabs demonstrated a similar, but nonsignificant rhythm of molting. We suggest that blue crabs approaching ecdysis aggregate in seagrass meadows, taking advantage of the refuge from predation that this structurally complex habitat affords. Lunar rhythmicity of molting activity may further reduce predation mortality through a dilution effect.


Variation In Planktonic Availability And Settlement Of Blue-Crab Megalopae In The York River, Virginia, Ej Olmi, J Van Montfrans, Rn Lipcius, R J. Orth, Pw Sadler Jan 1990

Variation In Planktonic Availability And Settlement Of Blue-Crab Megalopae In The York River, Virginia, Ej Olmi, J Van Montfrans, Rn Lipcius, R J. Orth, Pw Sadler

VIMS Articles

Blue crab, Callinectes sapidus, megalopae and juveniles were sampled in the plankton and on natural (grassbeds) and artificial settlement substrates (collectors) at two sites in each of two areas of a lower Chesapeake Bay tributary (York River, Virginia) to examine spatial variability in blue crab recruitment. Spatial patterns of abundance were not consistent across habitats (plankton, artificial collectors and grassbeds) or time. Densities of planktonic megalopae were homogeneous at 1-2 m (within site) but varied at spatial scales of hundreds of meters (between sites) and kilometers (between areas). Settled megalopae were distributed unevenly within and between sites, but their abundance ...


Stomach Contents And Parasite Infestation Of School Bluefin Tuna Thunnus-Thynnus Collected From The Middle Atlantic Bight, Virginia, David B. Eggleston, Eleanor A. Bochenek Jan 1990

Stomach Contents And Parasite Infestation Of School Bluefin Tuna Thunnus-Thynnus Collected From The Middle Atlantic Bight, Virginia, David B. Eggleston, Eleanor A. Bochenek

VIMS Articles

No abstract provided.


Blue-Crab Population-Dynamics In Chesapeake Bay - Variation In Abundance (York River, 1972-1988) And Stock-Recruit Functions, Rom Lipcius, Wa Van Engel Jan 1990

Blue-Crab Population-Dynamics In Chesapeake Bay - Variation In Abundance (York River, 1972-1988) And Stock-Recruit Functions, Rom Lipcius, Wa Van Engel

VIMS Articles

Blue crab abundance in the York River, Virginia was analyzed for interannual, monthly and spatial variation at two stations sampled by bottom trawl from 1972-1988. Various stock-recruitment and recruit-stock functions were derived from trawl abundance and commercial fishery landings statistics. The key component of variation was due to interannual fluctuations in abundance, which remained consistently high or low for two or more years before changing, suggesting internal population feedback mechanisms, such as cannibalism, or long-term climatic control. In addition, significant cyclic patterns in residuals from stockrecruitment functions further indicated the existence of long-term variability in abundance. Peak seasonal abundance and ...


Shelter Scaling Regulates Survival Of Juvenile Caribbean Spiny Lobster Panulirus Argus, Db Eggleston, Rom Lipcius, Dl Miller, L Cobacetina Jan 1990

Shelter Scaling Regulates Survival Of Juvenile Caribbean Spiny Lobster Panulirus Argus, Db Eggleston, Rom Lipcius, Dl Miller, L Cobacetina

VIMS Articles

No abstract provided.


Small-Scale Organism Distributions And Patterns Of Species Diversity: Evidence For Positive Interactions In An Estuarine Benthic Community, Linda C. Schaffner Jan 1990

Small-Scale Organism Distributions And Patterns Of Species Diversity: Evidence For Positive Interactions In An Estuarine Benthic Community, Linda C. Schaffner

VIMS Articles

No abstract provided.


Planktonic Availability, Molt Stage And Settlement Of Blue Crab Postlarvae, Rom Lipcius, Ej Olmi, J Van Montfrans Jan 1990

Planktonic Availability, Molt Stage And Settlement Of Blue Crab Postlarvae, Rom Lipcius, Ej Olmi, J Van Montfrans

VIMS Articles

No abstract provided.


Settlement Patterns Of Crassostrea Virginica (Gmelin, 1791) Larvae In Relation To Tidal Zonation, G. Curtis Roegner, Roger L. Mann Jan 1990

Settlement Patterns Of Crassostrea Virginica (Gmelin, 1791) Larvae In Relation To Tidal Zonation, G. Curtis Roegner, Roger L. Mann

VIMS Articles

Experiments were conducted to determine the settlement distribution of the oyster Crassostrea virginica (Gmelin) in relation to tidal zonation in an area where adult populations are largely confined to the intertidal zone. Hatchery-reared pediveliger larvae were interned in PVC tubes positioned at known tidal heights. The influence of non-tidal factors was limited: mesh covering the ends of the tubes prevented loss of larvae to dispersal or predation, the settling substrate was not colonized by competitors, and the effects of light and horizontal currents were minimized. Settlement was found to occur throughout the intertidal zone but predominated at the bottom of ...


Utilization Of Marsh And Seagrass Habitats By Early Stages Of Callinectes-Aapidus - A Latitudinal Perspective, R J. Orth, J Van Montfrans Jan 1990

Utilization Of Marsh And Seagrass Habitats By Early Stages Of Callinectes-Aapidus - A Latitudinal Perspective, R J. Orth, J Van Montfrans

VIMS Articles

Seagrass beds and marshes have been identified as important nurseries for the blue crab, Callinectes sapidus. This nursery paradigm is based on blue crab abundance data from trawl, seine and drop-net sampling that has revealed greater abundances in these habitats than in adjacent unvegetated areas. Recently, more quantitative and intensive sampling in seagrass beds and marshes over broad latitudinal scales, combined with manipulative experiments, indicate that the same habitat may vary in utilization on regional scales. Mechanisms accounting for enhanced abundances in these nursery habitats have not been elucidated from a latitudinal perspective. Regional comparisons of blue crab catch data ...


Foraging Behavior Of The Blue-Crab, Callinectes-Sapidus, On Juvenile Oysters, Crassostrea-Virginica - Effects Of Prey Density And Size, Db Eggleson Jan 1990

Foraging Behavior Of The Blue-Crab, Callinectes-Sapidus, On Juvenile Oysters, Crassostrea-Virginica - Effects Of Prey Density And Size, Db Eggleson

VIMS Articles

Blue crabs (Callinectes sapidus) are major predators of juvenile oysters (Crassostrea virginica) in Chesapeake Bay, yet little information exists on the foraging behavior and predatorprey dynamics for this predator-prey system. Laboratory experiments assessed functional responses of blue crabs to six densities of three size-classes of juvenile American oysters. Behavioral subcomponents of the crabs' functional response were quantified: total and successful encounter rates, proportional attack success, persistence time in unsuccessful encounters, and breaking, eating and handling times in successful encounters. Specific opening techniques were used by crabs for the three oyster size-classes. Blue crabs exhibited a hyperbolic type II functional response ...


Molting In The Mature Female Blue-Crab, Callinectes-Sapidus Rathbun, Kirk J. Havens, Jr Mcconaugha Jan 1990

Molting In The Mature Female Blue-Crab, Callinectes-Sapidus Rathbun, Kirk J. Havens, Jr Mcconaugha

VIMS Articles

The present study examined the hypothesis that mature female blue crabs, Callinectes sapidus, do not enter a terminal anecdysis. Induced molting via eyestalk ablation, size frequency distributions, gonad development and limb regeneration indices from field collected animals are used as indicators of potential post maturity molts. Eyestalk ablation of 15mature females resulted in ecdysis in II individuals approximately 51 days (standard error = 0.64) after ablation, indicating a physiological ability of mature females to complete ecdysis. Analysis of size frequency distributions from catch data indicated two distinct shifts from smaller to larger females, one in early spring and a second ...


Development Of The Reproductively Functional Form In The Male Blue-Crab, Callinectes-Sapidus, Wa Van Engel Jan 1990

Development Of The Reproductively Functional Form In The Male Blue-Crab, Callinectes-Sapidus, Wa Van Engel

VIMS Articles

The progression of the morphological features of the male blue crab reproductive system that culminate in puberty involves one change in the gonad, four combinations of the method and degree of adherence of the abdomen to the sternum, four variations in the positions of the penes, and four variations in the positions of the pleopods. The sequence of development appears to be established: (I) spennatophores must be present in the anterior vasa deferentia; (2) the abdomen must be completely free of the sternum, or, in addition, may be locked by the sternal tubercles; (3) and the penes and second pleopods ...


Systematics Of The Pearlfishes (Pisces, Carapidae), Df Markle, Je Olney Jan 1990

Systematics Of The Pearlfishes (Pisces, Carapidae), Df Markle, Je Olney

VIMS Articles

A review of taxonomy, anatomy, ontogeny, ecology, and phylogeny of the ophidiiform family Carapidae was conducted using over 2,300 larval, juvenile and adult specimens. A cladistic classification based on swimbladder morphology, developmental and osteological characters of the vertebral column, fins, pectoral and pelvic girdles, gill arches, ethmoid, jaws, and habitat is presented. A total of 31 species (6 new names and one unnamed larval form) in seven genera are recognized in two subfamilies. A species previously assigned to Echiodon is made the type of a new monotypic genus. Species of the tribe Carapini are rearranged in the genera Carapus ...


Daily, Monthly And Annual Settlement-Patterns By Callinectes-Sapidus And Neopanope-Sayi Megalopae On Artificial Collectors Deployed In The York River, Virginia - 1985-1988, J Van Montfrans, Ca Peery, R J. Orth Jan 1990

Daily, Monthly And Annual Settlement-Patterns By Callinectes-Sapidus And Neopanope-Sayi Megalopae On Artificial Collectors Deployed In The York River, Virginia - 1985-1988, J Van Montfrans, Ca Peery, R J. Orth

VIMS Articles

Daily, monthly and annual settlement of dominant brachyuran megalopae on six replicate artificial settlement substrates (collectors) was examined at one site in the York River, Virginia, from mid-July or early August to early December during 1985-1988. Callinectes sapidus Rathbun, an exported estuarine species, and Neopanope sayi (Smith), a retained estuarine species, were the numerically dominant colonizers of collectors. C. sapidus settlement was highly episodic (l-3-day duration) and significantly associated with the full moon period (lunar day 15-22). The temporal mean of settlement for C. sapidus each year fell within a 12-day period (24 September-6 October) over the 4 years. C ...


Oceanic Dispersion Of Larval Fish And Its Implication For Mortality Estimates - Case-Study Of Walleye Pollock Larvae In Shelikof Strait, Alaska, Suam Kim, Bohyun Bang Jan 1990

Oceanic Dispersion Of Larval Fish And Its Implication For Mortality Estimates - Case-Study Of Walleye Pollock Larvae In Shelikof Strait, Alaska, Suam Kim, Bohyun Bang

VIMS Articles

No abstract provided.


Differential Growth Among Cohorts Of Age-0 Weakfish Cynoscion-Regalis In Chesapeake Bay, Stephen T. Szedimayer, Mp Weinstein, John A. Musick Jan 1990

Differential Growth Among Cohorts Of Age-0 Weakfish Cynoscion-Regalis In Chesapeake Bay, Stephen T. Szedimayer, Mp Weinstein, John A. Musick

VIMS Articles

Age-0 weakfish Cynoscion regalis, were sampled from the Chesapeake Bay-York River estuary in 1983 and 1984 to test for the existence of multiple cohorts and compare growth rates. In both years juveniles were first collected in the estuary in late July, were significantly more abundant from August to mid-October, but were uncommon by the end of October. Significantly more weakfish were collected in 1983 than in 1984. Daily ages were determined based on scale circuli. Cohorts were separated by local minima in birthdate distributions: cohort 1 hatched before 16 July 1983, cohort 2 (16 July-15 August 1983), cohort 3 (15 ...


Effect Of Decreasing Oxygen Tension Of Swimming Rate Of Crassostrea Virginica (Gmelin, 1791) Larvae, Roger L. Mann, Julia S. Rainer Jan 1990

Effect Of Decreasing Oxygen Tension Of Swimming Rate Of Crassostrea Virginica (Gmelin, 1791) Larvae, Roger L. Mann, Julia S. Rainer

VIMS Articles

Four sizes of Crassostrea virginica Gmelin larvae (mean lengths 76.8, 118.1, 139.7 and 290.2 [Lm) were exposed to ·stepwise decreases in oxygen concentration from I 00% saturation (5 .38 mill at 22°C and 22 ppt salinity) to as low as 10% saturation and their swimming rates (net vertical movement per unit time) were recorded at each oxygen concentration. No cessation of swimming was observed and in only two conditions, that of 76.8 [Lm larvae at 10% saturation and 290.2 j.Lm larvae at 21% saturation, was swimming rate significantly lower than that of ...


Recruitment And Growth Of Oysters On Shell Planted At Four Monthly Intervals In The Lower Potomac River, Maryland, Reinaldo Morales-Alamo, Roger L. Mann Jan 1990

Recruitment And Growth Of Oysters On Shell Planted At Four Monthly Intervals In The Lower Potomac River, Maryland, Reinaldo Morales-Alamo, Roger L. Mann

VIMS Articles

Oyster shells were planted on four successive months (May to August 1986) in contiguous plots at Jones Shore Bar in the Potomac River, Maryland, to study the effect of differences in time of cultch planting on settlement and survival of oyster spat. The plots were usually sampled at two-week intervals from time of planting through November, 1986, and once in June, 1987. A massive concentration of the tunicate Molgula manhattensis covered the bottom in all plots within four to six or eight weeks following shell planting. A commercially acceptable number of spat per shell, between 1.8 and 2.2 ...