Michael Castagna

Aspects of an undescribed reproductive behavior inFundulus heteroclitus (Pisces: Cyprinodontae) from Virginia

Large numbers of eggs ofFundulus heteroclitus have been found in shells of the intertidal mussel,Modiolus demissus, near Wachapreague, Virginia, during six consecutive summers and in Brown’s Bay, Virginia, during 1972. Egg deposition in shells in aquaria has been observed. This behavior may serve to protect the eggs from predation. In nature the eggs in shells are exposed to high temperatures and desiccation for long periods during lower tide levels. Hatching has occurred in 14 to 17 day under these conditions. Eggs taken from mussel shells and eggs stripped and fertilized in the laboratory did not have chorionic filaments or the filaments were greatly reduced in number and length. The habit of egg deposition in shells and the morphology of the eggs are different from that reported forF. heteroclitus from Woods Hole, Massachusetts.

Marine fishes of Virginia’s eastern shore (Inlet and marsh, seaside waters)

A small trawl and beach seine survey was made, June 1965–July 1966, of marine fishes inhabiting 27 selected stations in seaside waters of Virginia’s Eastern Shore. Seventy species were collected, 47 by trawl and 52 by seine. Eleven species are considered resident. Ten species made up 97.8% of the total number collected withMenidia menidia being the most abundant. A checklist of 96 species known to inhabit the area is given with hydrographic and distribution details for each species when known. Species assemblages by seasons for inlet, midchannel, inshore beaches, and tidal creeks are also given in tabular form.

Ultrastructure of the Nebenkörper or “secondary nucleus” of the parasitic amoeba Paramoeba perniciosa (Amoebida, Paramoebidae)

Abstract The fine structure of the Nebenkorper or secondary nucleus of Paramoeba perniciosa is described. It consisted of one or two eukaryotic nuclei and a prokaryotic-like nucleoid with cytoplasm surrounding each of the two regions. The cytoplasm contained, as normal constituents, ribosome-like particles and phagosomes with the latter containing cytoplasm of the amoeba. No Golgi bodies, endoplasmic reticulum, or mitochondria were observed. Oval, bipolar Nebenkorpers were observed in which one eukaryotic nucleus was present at each pole, separated by a prokaryotic-like nucleoid. Such Nebenkorpers were derived from division of the eukaryotic nucleus in unipolar forms. On the basis of its structure and division, the Nebenkorper appears to be a discrete organism, not an organelle of the amoeba; however, an accurate determination cannot be made until adequate biochemical and physiological information is available concerning its interactions with the amoeba. If the Nebenkorper is a discrete organism, then its taxonomic affinities are uncertain since there are no known taxa in which it could be placed.

Shell morphology and identification of early life history stages of congeneric species of Crassostrea and Ostrea

Series of sequences of SEM micrographs are presented to elucidate species-specific shell features in larval and post-larval stages of four Ostreidae (Bivalvia) species ( Crassostrea gigas (Thunberg), C. virginica (Gmelin), Ostrea edulis L., and O. equestris Say). The diagnostic characters, including hinge structure, shell shape, and the dimensions of the prodissoconch, are identified and summarized in a key at both generic and species levels. In larval Crassostrea the skewed, backwards-pointed umboned shells with two hinge teeth on each side of the provinculum are significantly different from the round, dorsally-directed umboned shell with fewer, remarkably asymmetric teeth of larval Ostrea .In C. gigas the dimensions of the provinculum are longer and narrower (56x10 µrn) than those of C. virginica (50x14 µm); the lengths of prodissoconch I and the provinculum are greater in O. edulis (168 µm and 86 µm, respectively) than in O. equestris (120 µm and 74 µm, respectively). The present study suggests that precise quantitative measurements are needed for differentiation of the studied congeneric oyster species.

Effects of the treatment of an oyster bed with Polystream and Sevin

A series of field tests near Wachapreague, Virginia, in 1963 evaluated Polystream and Sevin mixed with sand as a means of controlling populations of oyster drills,Urosalpinx cinerea. Tests were designed to evaluate effects on planted oysters, drills, drill egg case deposition, crabs, and benthic invertebrates. Application of the chemicals to planted oyster beds did not reduce drill populations or numbers of drill egg cases deposited. Oyster production was not increased and treatment had an adverse effect on most species of benthic macroinvertebrates. Absence of drill control could have been associated with mixing of treated sand into subsurvace deposits but other factors may have been involved.

Larval and early postlarval shell morphology of several venerid clams

Shell morphological features of the larvae and early postlarvae of species from two venerid (Mollusca: Lamellibranchia) subfamilies, Chioninae (Mercenaria mercenaria, M. campechiensis, M. campechiensis texana and Chionecancellata) and Pitarinae (Pitar morrhuanus) , were examined using scanning electron microscopy. A single elongated fold on the anterior half of the left valve became more robust and a small fold in the centre of the right valve increased in length along the hinge line throughout the larval period. A MANOVA of shell length, shell height and provinculum length detected statistically significant (P) differences between the larval shells of Chioninae and Pitarinae, and within the Mercenaria .

Larval Development of the Stout Razor Clam, Tagelus plebeius Solander (Solecurtidae: Bivalvia)'

Tagelus plebeius were spawned and their larvae reared in the laboratory. Length measured from 90 to 170 μ, height from 75 to 161 μ and depth from 45 to 131 μ during pelagic stages. The hinge line was 63 to 75 μ long. Larvae had a distinctive series of irregular teeth at both ends of the hinge line. They can be distinguished from other bivalve larvae by the hinge, the relatively great height of the umbo and shoulders, the much longer anterior shoulder and end, and a dark shell margin. Larvae complete pelagic development at a smaller size than any other known bivalve veliger (155–170 μ).

Sexual dimorphism in oyster drills of Chincoteague Bay, Maryland-Virginia

The sex and length of 5,475 oyster drills,Urosalpinx cinerea follyensis andEupleura caudata etterae, were determined to ascertain if a significant difference exists in the mean size of males and females. The mean length of femaleU. cinerea was 28 mm, and of males, 24 mm; of femaleE. caudata, 29 mm, and of males, 25 mm. Statistical treatment of the data indicates that females of both gastropod species are significantly larger than males.

Distribution, growth, and predation of juvenile white mullet (Mugil curema) in oceanside waters of Virginia’s eastern shore

Distribution, growth, and predation level data for juvenile white mullet (Mugil curema Valenciennes) were obtained in 1965 by shallow water seine hauls during an exploratory survey of oceanside embayments of Virginia’s eastern shore peninsula. Average minimum growth was 17.5 mm fork length per half-month period, June through September. Growth equations fitted with an analog computer are: Wt=615(1−e−0.78t)3 Lt=360(1−e−0.78(t+0.06)) Fork lengths are in mm and weights are in grams. Highest predation incidence, 49%, was observed in late September inlet collections. Literature data implies juvenile white mullet, that occur north of North Carolina, have a southern origin.

Comments on the abundance and ecology of the ascidianAmaroucium constellatum in Sinepuxent and Chincoteague Bays

The ascidianAmaroucium constellatum inhabits the shallow coastal Sinepuxent and Chincoteague Bays and was found predominantly over mud, mud-oyster, oyster bottoms or on pilings and occasionally on the oyster drill,Urosalpinx cinerea, where moderate currents and salinities above 28 ppt prevail.A. constellatum was also noted on sand bottoms to a depth of five fathoms in coastal waters near Chincoteague, Virginia.