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Observations On Extant Populations Of The Softshell Clam, Mya Arenaria Linné, 1758 (Bivalvia: Myidae), From Georgia (Usa) Estuarine Habitats, Erik Rasmussen, Richard W. Heard

Gulf and Caribbean Research

The softshell clam, Mya arenaria Linné, 1758, is reported from Georgia (USA) estuarine habitats based on studies conducted between 1969 and 1972. Observations on Georgia estuarine habitats where extant populations of softshell clams occurred are described. On several occasions, fresh shells with periostracum and tissue remnants were found in a brackish drainage system on Sapelo Island. These shells represent the first southern records of extant populations of softshell clams from such a specialized habitat type. Living specimens of M. arenaria from the benthos and specimens in the stomach contents of stingrays (Dasyatis sabina) were collected at four stations …

Influences Of Larval Settlement Location And Rate On Later Growth And Mortality In A Sessile Marine Invertebrate Population (Spirorbis Spirillum), Joseph M. Dirnberger

Gulf of Mexico Science

Planktonic larvae of the tube-buildlng polycheate Spirorbis spirillum (Linnaeus) settle abundantly along seagrass blades of Thalassia testudinum Banks ex Konig in bays of the northern Gulf of Mexico. Detailed demographic parameters of settled Individuals were measured in situ by using biological stains that mark the leading margin of tubes containing living S. spirillum and this method yielded similar results when compared with independent estimates of settlement rate, growth, and mortality. Larvae tended to settle near the base of growing seagrass blades and subsequent survivorship and tube growth were highest for Individuals nearest the base. Survivorship that is positively affected by …

Winter Mass Mortality Of Animals In Texas Bays, Lawrence W. Mceachron, Gary C. Matlock, C.E. Bryan, Phil Unger, Terry J. Cody, Joe H. Martin

Gulf of Mexico Science

The Texas coast experienced three unusually cold weather periods in the 1980's, one in 1983 and two in 1989, that caused massive fish kills. Identification of organisms killed and estimation of the number of estuarine fishes and invertebrates killed was accomplished through a systematic standardized approach utilizing airplanes, ground qualitative observations and quantitative counts, and trawling. Of 159 species identified, 103 were fishes, 45 were invertebrates, and 11 were vertebrates other than fishes. About 14 million fishes were killed in December 1983, 11 million in February 1989 and 6 million in December 1989; number of invertebrates killed ranged from 13,000 …

Eleven New Species Of Free-Living Marine Nematodes, Edwin J. Keppner

Gulf and Caribbean Research

The genus Halalaimus is reviewed and divided into four groups based on characters of the male. Characters used to separate the groups of males include presence or absence of caudal algae and the presence or absence of a precloacal sensillum and/or pore. Ten new species are described from St. Andrew Bay, Bay County, Florida, and H. gerlachi n. sp. is proposed for H. gracilis sensu GerIach, 1967. New species from St. Andrew Bay are H. thalassinus, H. tarjani, H. bayensis, H. bulbocaudatus, H. variabilis, H. paracomatus, H. americanus, H. floridanus, H. brimi, …

Life History And Ecology Of Sand Seatrout Cynoscion Arenarius Ginsburg, In The Northern Gulf Of Mexico: A Review, James G. Ditty, Marty Bourgeois, Rick Kasprzak, Mark Konikoff

Gulf of Mexico Science

Sand seatrout usually represent from 5-7% of trawl catches by weight, 8-10% by number, and consistently rank among the top 5 most abundant species in demersal surveys. Sand seatrout mature at 140-180 mm TL, begin to enter the late developing, gravid, or ripe stages around 180 mm TL, and first spawn at 12 months. Spawning occurs primarily from March through September with distinct peaks in both March-April and August-September. Spawning initially takes place in midshelf to offshore waters and moves shoreward as the season progresses, with most occuring in the lower estuary and shallow GOMEX (7-15 m water depth). Larvae …

Distribution And Abundance Of Nearshore Fishes In The Anclote River Estuary, West-Central Florida, Stephen T. Szedlmayer

Gulf of Mexico Science

No abstract provided.

Diets Of Young King And Spanish Mackerel Off The Southeast United States, John H. Finucane, Churchill B. Grimes, Steven P. Naughton

Gulf of Mexico Science

The diet of larval and post-larval (n = 95 and 307), and juvenile (n = 489 and 508) king (Scomberomorus cavalia) and Spanish mackerel (S. maculatus) from the Gulf of Mexico and southeastern Atlantic coastal waters of the U.S. consisted principally of fishes. Carangids, clupeids, and engraulids occurred in 23, 7 and 9% of larval and post-larval king mackerel stomachs and in 20, 40 and 7% of larval and post-larval Spanish mackerel stomachs, respectively. Sciaenids were also common in king mackerel, occurring in 21% of the stomachs. Prey fishes included the genera Cynoscion, Caranx, …

Lower Temperature Tolerance Of Snook, Centropomus Undecimalis, Robert G. Howells, Albin J. Sonski, Paul L. Shafland, Brian D. Hilton

Gulf of Mexico Science

No abstract provided.

Early Life History Of The Snook, Centropomus Undecimalis, In Tampa Bay, Florida, Robert H. Mcmichael Jr., Kevin M. Peters, Glenn R. Parsons

Gulf of Mexico Science

Data accumulated during four sampling programs and incidental sampling are used to describe the distribution, growth, range of hatching dates, and diet of juvenile snook, Centropomus undecimalis, from Tampa Bay, Florida. A total of 1,655 juvenile snook ranging from 10 to 346 mm SL were collected (72% <70 mm SL). Small juveniles were common in small, quiet marshes, creeks, and lagoons, but their presence was not limited to areas with any single salinity range or vegetation type. Larger juveniles occupied similar habitats but were also found along more open bay and river shores. Length-frequency and otolith analyses were used to determine juvenile growth rates, which varied from 0.5 to 1.2 mm SL/day depending on the spawning date, size, and collection date. Growth data suggested that spawning took place from April until December, with peak spawning occurring in the summer (July to September). Juveniles <45 mm SL fed mainly on copepods and mysids; larger fish switched to a diet of palaemonid shrimp and cyprinodontid and poeciliid fishes.

Reproduction And Growth Of Black Drum, Pogonias Cromis, In Northeast Florida, Michael D. Murphy, Ronald G. Taylor

Gulf of Mexico Science

Age, growth, and reproduction of black drum, Pogonias cromis, in northeast Florida were investigated between December 1983 and April 1985. Male black drum began maturing at 450-499 mm total length (TL), with 50% of them reaching maturity at about 590 mm (age 4 or 5). Vitellogenesis began at 450-550 mm TL, with 50% of the females reaching maturity at 650-699 mm (age 5 or 6). Spawning occurred during January - April. Thin sections of otoliths displayed distinct opaque bands; the first three or four of these bands were verified by marginal increment analysis as being annuli deposited during March …

An Illustrated Key To The Chaetognatha Of The Northern Gulf Of Mexico With Notes On Their Distribution, Jerry A. Mclelland

Gulf and Caribbean Research

A key is provided to facilitate the identification of 24 species in nine genera of Chaetognatha occurring in the northem Gulf of Mexico. Included are the deep-water species, Eukrohnia proboscidea, E. calliops, Mesosagitta sibogae, and Sagitta megalophthalma, all recent additions to the known fauna of the region. Meristic data, brief descriptions, ecological notes, Gulf of Mexico records, and illustrations are also presented.

Tanaidacea (Crustacea: Peracardia) Of The Gulf Of Mexico. Vi. On The Genus Mesotanais Dollfus, 1897 With Descriptions Of Two New Species, M. Longisetosus And M. Vadicola, Jurgen Sieg, Richard W. Heard

Gulf and Caribbean Research

Two new species of tanaidaceans belonging to the family Leptocheliidae were collected from the continental shelves and slopes of the eastem and Gulf coasts of the United States. Both of these species are assigned to the poorly known genus Mesotanais Dollfus, 1897. Mesotanais is unique within the Leptocheliidae because its members lack eyes. The second supposedly important generic character, uniramous uropods, reported in the original description is considered to be a misdiagnosis. The assumption of this error is supported by the rediscovery of the type-species, Mesotanais dubius Dollfus, 1897 (Sieg and Bird, in press). In the present study, the genus …

New Records Of Fishes In The Northwestern Gulf Of Mexico, With Notes On Some Rare Species, George D. Dennis, Thomas J. Bright

Gulf of Mexico Science

Based on submersible, SCUBA, and trawl collections 14 new fish records are reported for the northwestern Gulf of Mexico. In addition the distribution of eight rare species are discussed in detail.

The Relative Abundance And Feeding Habits Of Juvenile Kingfish (Sciaenidae: Menticirrhus) In A Gulf Of Mexico Surf Zone, Robert H. Mcmichael Jr., Stephen T. Ross

Gulf of Mexico Science

We describe seasonal and diel occurrence patterns, density, dietary progressions, and trophic relationships of Menticirrhus littoralis, M. americanus and M. saxatitis collected from the Horn Island, Mississippi, surf zone. Menticirrhus littoralis was the most abundant species (62.7%), followed by M. americanus (21.8%) and M. saxatitis (15.5%). Densities were highest during spring and summer and decreased markedly during the winter. Species showed diel changes in abundance, with abundance increasing during dusk and dawn for M. littoralis, and during the day for M. americanus and M. saxatilis. All three species showed ontogenetic progressions in diet, with siphon tips from …

Feeding Habits Of Sheepshead, Archosargus Probatocephalus, In Offshore Reef Habitats Of The Southeastern Continental Shelf, George R. Sedberry

Gulf of Mexico Science

The feeding habits of sheepshead, Archosargus probatocephalus, were studied by examining contents of digestive tracts from fish collected on offshore live bottom reefs in the South Atlantic Bight. Sessile invertebrates were the most important prey for sheeps· head. Smaller sheepshead (<350 mm standard length) had a diet dominated by bryozoans. Larger sheepshead also fed heavily on bryozoans, but included more bivalves, echinoderms and ascidians in the diet. Barnacles and decapods were consumed in lesser amounts by both size classes. Foraminiferans, cnidarians, polychaetes, gastropods and small arthropods were also eaten. The sessile species utilized as prey by sheepshead are common colonial organisms found on offshore reefs. Motile epifaunal species consumed by sheepshead were common species associated with hard substrates or sessile species. Predation by sheepshead may be important in regulating the structure of epifaunal communities in reef habitats.

Occurrence, Growth, And Food Habits Of The Spotted Hake, Urophycis Regia, In The Cape Fear Estuary And Adjacent Atlantic Ocean, North Carolina, Brooks M. Burr, Frank J. Schwartz

Gulf of Mexico Science

From 1973 to 1978, 62,867 Urophycis regia were collected from the Cape Fear Estuary, North Carolina, and the adjacent Atlantic Ocean. Most fish were young-of-the-year (25-225 mm SL), but a few age-l individuals (230-295 mm) were present in the estuary from January to June. They moved offshore or northward when water temperatures warmed above 22°C. Average monthly growth increments varied from 12 to 26 mm SL; the greatest increase in length was 92 mm from January to June 1977. Length-weight regressions for the 6-year study period were similar. Important food items were crustaceans (largely mysid shrimp and decapods) and fishes …

Fish Assemblages And Benthic Biota Associated With Natural Hard-Bottom Areas In The Northwestern Gulf Of Mexico, Russell E. Putt, David A. Gettleson, Neal W. Phillips

Gulf of Mexico Science

We report new observations of fish and benthic invertebrate assemblages at shallow-water (<35 m depth), hard-bottom sites in the northwestern Gulf of Mexico. The biota of these previously unstudied areas and of three high-relief features in deeper water was observed during May 1980 using a combination of diver reconnaissance, videotape surveys, still-camera photography, and collection of invertebrates for identification. The six hard-bottom sites in shallow water typically comprised, small, often patchy, rock outcrops, and the associated sessile invertebrates included hydroids, bryozoans, sponges, octocorals, and ahermatypic stony corals. Sea urchins and arrow crabs were the most common motile epifauna. Fish assemblages were typified by red snapper, Atlantic spadefish, blue runner gray triggerfish, sheepshead, and tomtate. Three deeper stations had many of the same fish and invertebrate species, but also possessed a more tropical assemblage including fire corals, antipatharians, spiny lobsters, and a variety of tropical fish species. Hermatypic corals characteristic of some large, offshore banks were not abundant at any of the sites.

Differences in the composition of fish assemblages between nearshore and deeper stations parallel those previously observed at petroleum platforms in the area. Shallow-water stations presumably experience a greater seasonal temperature range and lower absolute temperatures in winter and may be exposed to stresses such a lowered salinity and depleted oxygen levels due to their relative proximity to Mississippi River discharge. The fauna of these shallow hard-bottom sites has predominantly warm-temperate rather than tropical affinities.

Distribution And Relative Abundance Of Butterflyfishes And Angelfishes Across A Lagoon And Barrier Reef, Andros Island, Bahamas, David G. Lindquist, Matthew R. Gilligan

Gulf of Mexico Science

Juveniles of Chaetodon capistratus, C. striatus, C. ocellatus, C. sedentarius, Pomacanthus arcuatus, P. paru, Holacanthus ciliaris, and H. tricolor occurred in the shallow lagoon habitats. Adults and subadults of these species were associated with the deeper barrier reef and seaward platform habitats. C. aculeatus occurred only on the outer seaward platform. In strip transects at a seaward platform site, C. capistratus and H. tricolor were found with significantly greater abundance than P. paru and C. striatus.

A Small Mammal Trapping Study Of The Floating Freshwater Marshes Surrounding Lake Boeuf, Louisiana, Robert K. Abernethy, Gary W. Peterson, James G. Gosselink

Gulf of Mexico Science

No abstract provided.

Vegetational Composition Of The Upper Barataria Basin Swamp, Louisiana, William H. Conner, Charles E. Sasser

Gulf of Mexico Science

No abstract provided.

Macroinvertebrate Colonization Of The Intertidal Habitat Of A Dredge Spoil Island In North Florida, C.B. Subrahmanyam

Gulf of Mexico Science

Macroinvertebrate colonization of the intertidal habitat of a dredge spoil island was studied for one year by collecting triplicate 0.0625-m² x 10-cm core samples of substratum from four stations established relative to the slope of the habitat. Fauna first colonized the subtidal site, and after lapses of time appeared respectively at low, mid and high-tide stations. The total abundance and diversity of the assemblage increased significantly in the latter half of the year mainly due to the appearance of late colonizers at low and mid-tide stations. The temporal abundance patterns at the four stations were variable. Several species that …

The Epiphytic Diatom Flora Of Two Sargassum Species, Robert S. Maples

Gulf and Caribbean Research

The epiphytic diatom flora on the brown algae Sargassum natans (L.) J. Meyer and S. fluitans Børgesen were investigated and compared. A total of 50 taxa representing 21 genera were identified. The most abundant taxa were Amphora exigua Greg., A. coffeiformis (Ag.) Kütz., Synedra fasciculata (Ag.) Kütz., Cocconeis pseudodiruptoides Foged, and Navicula ramosissima (Ag.) Cleve. Comparisons of the dominant species and diversity statistics characterizing the two samples indicated the two brown algal species supported nearly identical epiphytic diatom floras.

Distribution And Ecology Of The Synaphobranchidae Of The Gulf Of Mexico, Douglas M. Martin

Gulf and Caribbean Research

Synaphobranchid eels of the Gulf of Mexico are an important part of the upper continental slope ichthyofauna, occurring most frequently between 500 and 1,500 m. Two of the four known genera (Histiobranchus and Diastobranchus) have not been reported from the Gulf. Synaphobranchidae tend to occur within a narrow range of temperatures compared to the North Atlantic synaphobranchid eels. However, distribution of these eels in the deeper parts of the Gulf appears to be correlated more to change in depth than to temperature, salinity, or dissolved oxygen. The distribution at the shallower limits of their depth range appear to …

Trophic Relationships Of Fishes Occurring Within A Surf Zone Habitat In The Northern Gulf Of Mexico, Timothy Modde, Stephen T. Ross

Gulf of Mexico Science

We studied trophic relationships of Florida pompano (Trachinotus carolinus), gulf kingfish (Menticirrhus littoralis), scaled sardine (Harengula jaguana), striped anchovy (Anchoa hepsetus) and dusky anchovy (A. lyolepis) during their spring residency in the Horn Island, Mississippi, surf zone. Harengula jaguana, A. lyolepis and A. hepsetus were zooplanktivores, utilizing primarily calanoid copepods, mysids and various decapod larvae. Menticirrhus littoralis and T. carolinus utilized benthic prey including Donax, Emerita and polychaetes; however, small pompano also fed on zooplankton. Menticirrhus littoralis, T. carolinus, H. jaguana and A. lyolepis also showed …

A Lower Lethal Temperature For Fingerling Snook, Centropomus Undecimalis, Paul L. Shafland, Karen Jo Foote

Gulf of Mexico Science

No abstract provided.

A Character Analysis Of Gobionellus Boleosoma And G. Shufeldti (Pisces: Gobiidae) From The North-Central Gulf Of Mexico, Frank L. Pezold, Robert C. Cashner

Gulf of Mexico Science

No abstract provided.

Distribution Of The Marsh Periwinkle Littorina Irrorata (Say) In A Virginia Salt Marsh, R. Wyle Crist, William C. Banta

Gulf and Caribbean Research

Littorina irrorata varies over its geographic range in maximum size, preferred elevations relative to tidal datum planes, and in the type of vegetation it inhabits. On Wallops Island, Virginia, postlarvae of Littorina irrorata with shell lengths < 5 mm long live almost exclusively in dead, curled-up leaves of Spartina alterniflora at elevations near mean tide level, below elevations occupied by larger conspecifics. Snails longer than 5 mm in length increase in average size with decreasing elevation. This distribution is opposite to that found by Hamilton (1978) in a marsh in Florida. No difference was found in our study area in growth rate of marked snails at two different elevations, so the size-elevation …

Effects Of Saltwater Intrusion From The Inner Harbor Navigation Canal On The Benthos Of Lake Pontchartrain, Louisiana, Jane A. Junot, Michael A. Poirrier, Thomas M. Soniat

Gulf and Caribbean Research

A study of the benthos of southern Lake Pontchartrain, Louisiana, was conducted from July 1976 to July 1978. Seven offshore stations and three stations in the New Orleans Marina complex were sampled seasonally. Offshore stations formed a transect from the Lake Pontchartrain Causeway to the Inner Harbor Navigation Canal (I.H.N.C.). A west to east gradient of increasing salinity and salinity stratification was evident.

Faunal differences among stations were assessed using indices of diversity, biological dominance, pollution, and station homogeneity. The fauna of the marina stations had a low species diversity and was dominated by annelids, indicative of a stressed environment. …

Commentary: A Need For More Experimental Work In Estuarine Fisheries Ecology, Michael P. Weinstein

Gulf of Mexico Science

No abstract provided.

Food Contents Of Six Commercial Fishes From Mississippi Sound, Robin M. Overstreet, Richard W. Heard

Gulf and Caribbean Research

Specific dietary contents from six fishes collected in Mississippi Sound are recorded. In order of their importance, primary components grouped in major taxonomic categories were fishes, penaeid shrimps, and other crustaceans for Cynoscion nebulosus; Crustaceans and fishes for C. arenarius; fishes and crustaceans for C. nothus; crustaceans, pelecypods, and polychaetes for Pogonias cromis; crustaceans, molluscs, polychaetes, and fishes for Archosargus probatocephalus; and fishes and penaeid shrimps for Paralichthys lethostigma. Principal items in the diets of most of the fishes included Anchoa mitchilli, Penaeus aztecus, P. setiferus, and Callinectes sapidus. Those …