Austin B. Williams

A ten-year study of meroplankton in North Carolina estuaries: Amphipods

Occurrence of gammarid and caprellid amphipods in semimonthly nocturnal surface plankton samples taken on flood tide for 10 years at one estuarine station and shorter periods at 11 other stations is summarized on a monthly basis. Fifty-eight species are identified from samples taken during the study but no single station produced this variety. The great diversity of species from stations near the sea is contrasted with the sparse and different fauna of meso-oligohaline waters. Seasonal abundance in samples is summarized for all important species on a station basis. Contrasts in density of 8 species in surface-bottom tows and 33 species in samples taken at alternate lunar phases (new-full) indicate significant behavioral differences. Nocturnal stratification varied with species; about 1/3 showed no apparent abundance in association with lunar phase, another 1/3 showed increase at new, and a final 1/3 at full moon.

A ten-year study of meroplankton in North Carolina estuaries: Annual occurrence of some brachyuran developmental stages

Seasonal occurrence of brachyuran developmental stages is predictable in meroplankton collected inside the barrier islands of North Carolina near inlets and along longitudinal transects of the larger estuaries. Nets of 1 mm mesh employed in the sampling program limited catches to larger zoeae and megalopae, and of these only a fraction can be identified with precision.Callinectes megalopae were taken in every month of the year and through almost the entire lenghth of the estuary. Evidence indicates that this postlarval stage is active in surface waters at night, contributing substantially to dispersal of the species, probablyC. sapidus in this case.Hexapanopeus angustifrons megalopae were limited to the warm season in samples from a single station near Beaufort Inlet.Rhithropanopeus harrisii zoeae and megalopae were distributed abundantly in oligo-mesohaline waters of Neuse and Pamlico Rivers. Showing no nocturnal stratification, the stages were present continuously from June to October. Megalopae of all these species, usually considered benthic in habit, are readily captured in surface waters at night.

A Ten-year Study of Meroplankton in North Carolina Estuaries: Mysid shrimps

Seven species of mysid shrimps taken in semiquantitative, nocturnal, surface plankton samples showed variable levels of abundance and frequency of occurrence from stations near the sea to the head of estuaries in North Carolina. Bowmaniella dissimilis occurred mainly in samples from stations near the sea in every month of the year, and reached its greatest abundance from spring through autumn coincident with its breeding season. B. johnsoni was taken at stations near the sea only twice. Mysidopsis bigelowi, the second most abundant species, occurred in samples from every station, and was in breeding condition throught the estuaries from late winter to mid-autumn. Metamysidopsis mexicana occurred sporadically in samples from 3 stations near inlets, was in breeding condition throughout the year, but appeared to be abundant in summer and fall. Promysis atlantica appeared infrequently at stations near inlets in all months except Feb. and Mar., usually in breeding condition. Neomysis americana was the most abundant species, reaching its greatest concentration in samples from middle to upper estuarine stations where spawners were almost always present. Size differentials suggested more than a single generation per year. The species showed no evidence of nocturnal stratification in the shallow 6-m deep estuarine water. Heteromysis formosa occurred sporadically from May to Dec.

A ten-year study of meroplankton in North Carolina estuaries: Cycles of occurrence among penaeidean shrimps

Densities of postlarvalPenaeus species,Trachypeneus constrictus, Acetes americanus carolinae, andLucifer faxoni are discussed for surface plankton samples taken at a series of estuarial stations maintained for up to 10 years. Semiquantitative data forPenaeus show frequency distributions of log-normal type. Densities vary among years, within years in accord with predictable recruitment seasons, and among localities in expected relationship to habitat. In general, samples with highest densities were from areas near the sea. Some inland areas with presumably suitable salinity-temperature regimes may lie beyond the zone of effective tidal transport for these shrimps. Species not belonging toPenaeus are warm-weather transients penetrating the estuarial system as conditions permit.

A ten-year study of meroplankton in North Carolina estuaries: Occurrence of postmetamorphal bivalves

Occurrence of postmetamorphal bivalves known to have swimming ability is seasonally predictable in surface meroplankton in nocturnally flooding tidal currents near inlets inside the barrier islands of North Carolina. Samples from three stations-Institute of Marine Sciences pieer near Beaufort Inlet, inside Drum Inlet 20 mi N E of Cape Lookout, and inside Lockwoods Folly Inlet 10 mi W of Cape Fear River-were comparable.Ensis directus occurred abundantly from December to June at each of the stations;Tagelus divisus abundantly from May to September and sparsely in December at the Institute pier, and sparsely also at Lockwoods Folly Inlet in September;Solemya velum regularly from April to August at the Institute pier, rarely at Drum Inlet; andSolen viridis sparsely in midsummer at the Institute pier. Though these species are known to swim, no regularly recorded occurrence has ever been documented. A set of non-swimming molluscan species present in the samples were perhaps eroded from nearby source beds by strong currents. At Drum Inlet stationDonax variabilits occurred regularly during summer-fall, andPetricola pholadiformis during winter-spring. At Lockwoods Folly Inlet stationSpisula raveneli occurred regularly during spring-summer. Other species were rare. Seasonal occurrence of these species in the plankton samples remains unexplained.

A New Genus and Species of Snapping Shrimp (Decapoda, Alpheidae) From the Southeastern United States

[Leptalpheus forceps, nouveau genre et nouvelle espece de la famille des Alpheidae, est decrit de la cote atlantique des Etats-Unis. Cette espece habite dans les tubes dUpogebia affinis (Say), mais a ete egalement recueillie de nuit parmi le plancton, dans les estuaires. Une femelle ovigere a ete recueillie en aout dans un tube dUpogebia., Leptalpheus forceps, nouveau genre et nouvelle espece de la famille des Alpheidae, est decrit de la cote atlantique des Etats-Unis. Cette espece habite dans les tubes dUpogebia affinis (Say), mais a ete egalement recueillie de nuit parmi le plancton, dans les estuaires. Une femelle ovigere a ete recueillie en aout dans un tube dUpogebia.]

Notes On Structure and Parasitism of Munida Iris a. Milne Edwards (Decapoda, Galatheidae) From North Carolina, U.S.A

Se presentan datos en relacion con la estructura de la populacion y el parasitismo en una muestra de Munida iris. La muestra de 251 individuos muestra (i) una relacion mayor del 1 : 1 de hembras (63.7%) en comparacion con machos (36.3%); (ii) 84.3% de hembras ovigeras conteniendo alrededor de 7900 huevos cada una; (iii) una tendencia marcada de los machos de mayor edad y presumiblemente mas maduros, de sobrepasar a las hembras y a los machos inmaduros en tamano de cuerpo y desarrollo de las quelas; y (iv) el 10% de la muestra parasitado por epicarideanos.

New Records of Brachyuran Decapod Crustaceans From the Continental Shelf Off North Carolina, U.S.A

Vingt-neuf especes de Crustaces Decapodes sont signales du plateau continental, au large de la Caroline du Nord, U.S.A. Vingt-et-un dentre eux le sont pour la premiere fois de cette region (extensions geographiques); pour les huit autres ce sont des confirmations de captures precedentes. De nouvelles illustrations sont donnees pour 17 especes, ainsi que des notes sur les tailles maximales, la couleur et les conditions de reproduction, et sur les donnees geographiques et bathymetriques.

An unusually large turtle barnacle (Chelonibia p. patula) on a blue crab from Delaware Bay

A turtle barnacle,Chelonibia patula patula (Ranzani) of unusually large size was found on a large female blue crab in Delaware Bay in September, 1954. This appears to be the largest known specimen ofC. p. patula. The crab carapace was also fouled with the bryozoan,Alcyonidium polyoum (Hassall), and the hydroid,Hydractinia echinata (Fleming). On the basis of established criteria for judging the spawning history of adult female blue crabs, it is inferred that the host crab had spawned two or more times, was at least 25 or 26 months old at time of capture, and that the large barnacle was at least one year of age.

A ten-year study of meroplankton in North Carolina estuaries: Juvenile and adultOgyrides (Caridea: Ogyrididae)

Two species of alpheid-like burrowing shrimp,Ogyrides limicola andO. alphaerostris, occurring in estuaries of North Carolina were taken frequently in nocturnal surface plankton samples.Ogyrides limicola is fairly widespread in meso-polyhaline reaches of the estuarine system butO. alphaerostris appears to be confined to immediate vicinity of inlets. Samples from this study and museum collections provide evidence that the animals have a one-year life cycle with a spawning season in summer. Females greatly outnumber males in most collections studied.