ABSTRACTS
(Volume 10, March 1998)



FEEDING OF SCIAENID (PISCES: SCIAENIDAE) LARVAE IN TWO COASTAL LAGOONS OF THE GULF OF MEXICO

Alberto Ocaña-Luna1
Marina Sanchez-Ramirez2

1Escuela Nacional De ciencias Biologicas. Instituto Politecnico Nacional. Prol. De Carpio Y Plan De Ayala 11340 Mexico, D. F. Mexico.
2Instituto De Ciencias Del Mary Limnologia. Universidad Nacional Autonoma de Mexico. Apartado Postal 70-305. Mexico 04510, D.F. Mexico.

ABSTRACT
Stomach contents analyses showed that Leiostomus xanthurus (8.50-12.90 mm SL) had an wide trophic spectrum (15 food categories) with copepods and eggs of invertebrates as main components. In contrast, Micropogonias undulatus (6.65-12.20 mm SL) ingested only six food categories (copepods, eggs of invertebrates, crustacean nauplii, barnacle nauplii, amphipods and other crustaceans). There is an overlap of 73.2 to 83.0% in the diet of these two species. Bairdiella chrysoura (1.17-1.92 mm SL) fed primarily on juvenile pelecypods, crustacean nauplii, eggs of invertebrates, including gasteropods and copepods. Cynoscion nebulosus (1.50-2.42 mm SL) ingested juvenile pelecypods, copepods, crustacean nauplii, eggs of invertebrates and tintinnids, variability in  overlap (47.4 to 79.5%) between these species was affected by size of the larvae.
 

GENETIC VARIATION IN THE CAROLINA MARSH CLAM, POLYMESODA CAROLINIANA

W. D. Grater, C.T. Hackney, D. J. Covington

Gulf Coast Research Laboratory, Institute of Marine Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564, USA
Department of Biological Sciences, The University of North Carolina at Wilmington
Wilmington, NC 28403, USA
Department of Biology, Cape Fear Community College, Wilmington, NC 28401, USA

ABSTRACT
Horizontal starch gel electrophoresis was used to detect genetic variation at eight enzyme loci and five general protein loci in 11 populations of Polymesoda caroliniana from the Gulf of Mexico and south Atlantic coast of the U. S. Little variability was found between four of these populations along a salinity gradient in the Cape Fear Estuary, NC, and a regional trend was not observed in other populations along a latitudinal gradient.  Heterogeneity analysis and dendrograms, both based on allele frequencies, suggest populations from the Gulf coast of Florida are genetically different from both a northern Gulf population (Mississippi) and Atlantic populations.  The population from Mississippi was similar to populations from the Atlantic coast, all of which were similar.  Heterozygosity in the 11 populations ranged between 8.11 and 28.0%, and the percentage of loci polymorphic between 37.5 and 71.4%. Populations conformed to Hardy-Weinberg expectations at greater than 95% of all loci assayed except glucose dehydrogenase, where only the populations from Fort Myers, FL and Sapelo Island, GA conformed to Hardy-Weinberg expectations. Electrophoretic patterns observed suggest P. caroliniana larvae are planktonic and effective at dispersal.
 

EFFECTS OF THE BURROWING BRITTLESTAR, MICROPHIOPHOLIS GRACILLIMA (ECHINODERMATA: OPHIUROIDEA), ON THE FLUX OF LITHIUM, AN INERT TRACER, ACROSS THE SEDIMENT-WATER INTERFACE

Timothy H. Shepherda, d
Stephen E. Stancyka, b
Timothy J. Shawa, c

a ) Marine Science Program and Belle W. Baruch Institute for Marine Biology and Coastal Research, University of South Carolina, Columbia, SC 29208.
b ) Department of Biological Sciences, University of South Carolina, Columbia, SC 29208.
c ) Department of Chemistry, University of South Carolina, Columbia, SC 29208.
d ) current address: University of Georgia, Marine Institute, Sapelo Island, GA 31327

ABSTRACT
Burrowing and ventilation activities of infaunal organisms have been shown to affect geochemical processes in sediments and at the sediment-water interface.  Although burrowing brittlestars are dominant in many benthic environments, their role in these processes is poorly known.  We tested the effect of the amphiurid brittlestar, Microphiopholis gracillima, on the flux of lithium ion from the sediment to the overlying water by using sediment cores with false bottoms for continuous flow of a Li+1-seawater solution.  Brittlestars at densities of 300 and 600 individuals×m-2 caused a 2-fold increase in the rate that Li was transported through the sediment.  Density of brittlestars appeared to have no effect on the flux of Li+1 from the sediment, indicating a possible threshold beyond which density increases do not influence fluxes of solute from the sediment.
 

OCCURRENCE OF A SYNCHRONOUS HERMAPHRODITIC STRIPED MULLET, MUGIL CEPHALUS, FROM THE NORTHERN GULF OF MEXICO

James S. Franks, Nancy J. Brown-Peterson, Dyan P. Wilson, Ronda J. Russell and Janaith K. Welker

University of Southern Mississippi, Institute of Marine Sciences, Gulf Coast Research Laboratory, 703 East Beach Drive, Ocean Springs, MS 39564

ABSTRACT
A synchronous hermaphroditic striped mullet, Mugil cephalus, was captured offshore of Southwest Pass, Louisiana on 6 December 1996 during the commercial roe mullet fishery harvest. The fish measured 412 mm FL, weighed 824 g and was determined to be 4 years old by otolith analysis. Gross examination of the gonads revealed four lobes: right and left ovaries and right and left testis which represents a unique occurrence among hermaphroditic fish. All lobes  ended in a common sperm duct/oviduct with the exception of the left ovary which had no oviduct. Both ovaries contained vitellogenic oocytes and both testis had freely running spermatozoa. Histological examination showed many oocytes undergoing final oocyte maturation, the presence of some post ovulatory follicles and lobules full of tailed spermatozoa. There was no evidence of the intermingling of sperm and oocytes within the gonad. The capture of this fish on the spawning grounds and the advanced stage of both ovarian and testicular development suggests spawning  probably would  involve the release of both oocytes and spermatozoa.
 

FOOD HABITS AND DIETARY OVERLAP OF NEWLY SETTLED  RED DRUM (SCIEANOPS OCELLATUS) AND ATLANTIC CROAKER (MICROPOGONIAS UNDULATUS) FROM TEXAS SEAGRASS MEADOWS

M. Andres Soto (corresponding author)
USM Institute of Marine Sciences, Gulf Coast Research Laboratory
703 East Beach Drive
Ocean Springs MS. 39564
Telephone #: (228) 872-4234
e-mail: andy.soto@usm.edu

G. Joan Holt
University of Texas Marine Science Institute
750 Channelview Dr.
Port Aransas TX. 78373

Scott A. Holt
University of Texas Marine Science Institute
750 Channelview Dr.
Port Aransas TX. 78373

Jay Rooker
University of Texas Marine Science Institute
750 Channelview Dr.
Port Aransas TX. 78373

ABSTRACT
Food habits and dietary overlap of newly settled larval and juvenile red drum and Atlantic croaker were examined during the period when the two species co-occur in seagrass nurseries.  A total of 274 red drum (4.00 - 19.99 mm SL) and 205 Atlantic croaker (8.00 - 17.99 mm SL) were used for this analysis.  Of the red drum stomachs examined, 8.4 % were empty while 28.8 % of Atlantic croaker stomachs contained no food.  Major prey items identified for both species were calanoid copepods, harpacticoid copepods and mysid shrimp across all size classes.  Ontogenetic trophic niche shifts were detected for red drum and Atlantic croaker. Type and quantity of food ingested by red drum was similar across all stations (Aransas Bay Station: 1H, 2T and 3H) examined.  Atlantic croaker ingested the same types of prey at all stations, but contained varying quantities of food throughout the study area.  In general, high dietary overlap was observed between red drum and Atlantic croaker with most overlap values (Schoener's index) exceeding 70 %.
 

AN ILLUSTRATED RECORD AND RANGE EXTENSION OF CALIGUS CHELIFER (COPEPODA, SIPHONOSTOMATOIDA) IN THE GULF OF MEXICO

E. Suárez-Morales, I.-H. Kim1 and I. López-Salgado2

El Colegio de la Frontera Sur (ECOSUR). A.P. 424. Chetumal, Quintana Roo 77000. Mexico. 1Dept. of Biology, Kangreung National University. Kangreung 210-702. South Korea. 2Est. de Inv. Oceanográfica Tampico. Secr. de Marina. Alvaro Obregón s/n. Col. Emilio Carranza. Cd. Madero, Tamaulipas 89540. Mexico.

ABSTRACT
A male specimen of the copepod Caligus chelifer Wilson, 1905, was collected during a plankton survey carried out during February 1994 off the Mexican coasts of the eastern Gulf of Mexico (Tamaulipas state). This is the first record of this species in Mexican waters and south of the 25°N in the Northwestern Atlantic. Taxonomic illustrations of the specimen are provided.
 

Gulf Coast Research Laboratory:
A MISSISSIPPI ACADEMY OF SCIENCES PROJECT THAT HAS COME OF AGE

Linda Skupien and Joyce M. Shaw
Gulf Coast Research Laboratory, Institute of Marine Sciences, University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564

ABSTRACT
A brief overview of the creation and growth of the Gulf Coast Research Laboratory, this article traces the institution's history and its strong relationship with the Mississippi Academy of Sciences. The Mississippi Academy of Sciences officially dedicated the Gulf Coast Research Laboratory (GCRL) with the opening of the first summer session at Magnolia State Park in Ocean Springs, Mississippi, on August 28, 1947. Mississippians in scientific and educational circles had worked for two decades toward creating a research and educational laboratory focused on the state's marine and coastal environments. The Academy's priorities were scholarly research and education. Political leaders' were interested in the potential for a direct effect on the economy of Mississippi. The evolution of that two-fold focus has created a unique institution that integrates scientific discovery with graduate, undergraduate and public education as well as with rapid and effective response to questions of public concern.