Mexico Off Research Articles

Philometra floridensis sp. n. (Nematoda: Philometridae) from the ovary of red drum Sciaenops ocellatus (Osteichthyes: Sciaenidae) off the coast of Florida, USA

A new nematode species, Philometra floridensis sp. n. (Philometridae), is described from male and female specimens found in the ovary of red drum, Sciaenops ocellatus (Linnaeus) (Sciaenidae, Perciformes), from the Gulf of Mexico off Treasure Island, Florida, USA. Based on light and scanning electron microscopy examination, the new species differs from most other gonad-infecting Philometra spp. in having a smooth gubernaculum with a distinct dorsal tooth on the distal tip. The new species is most similar to P. carolinensis Moravec, de Buron & Roumillat, 2006, but differs in length and shape of spicules. It can be distinguished from P. carolinensis and other species with unknown males, by the markedly greater body length of gravid females (up to about 100 cm). Philometra floridensis is the third valid gonad-infecting species of Philometra reported from sciaenids.

Psettarium anthicum sp. n. (Digenea: Sanguinicolidae) from the heart of cobia Rachycentron canadum (Rachycentridae) in the northern Gulf of Mexico

Psettarium anthicum sp. n. (Digenea: Sanguinicolidae) infects the myocardium and atrial wall of the cobia Rachycentron canadum (Linnaeus, 1766) (Rachycentridae) in the northern Gulf of Mexico off Mississippi, USA. It is the first member of Psettarium Goto et Ozaki, 1930 reported from other than the Indian Ocean or Pacific Ocean and the second species of the genus reported from cobia. It differs from its congeners by the combination of having posterior caeca with lateral projections appearing as thorns in lateral view and the male pore anterior to the oötype. The species of Psettarium, P. japonicum (Goto et Ozaki, 1929) (type species), P. tropicum Manter, 1940, P. sebastodorum Holmes, 1971, P. rachycentri (Lebedev et Parukhin, 1972) comb. n. (syn. Psettarioides rachycentri Lebedev et Parukhin, 1972) and P. anthicum sp. n., differ from other sanguinicolids by the combination of having an elongate body with a sinistral posterolateral protuberance, minute, straight tegumental body spines in ventrolateral transverse rows, posterior caeca greater than seven time the anterior caeca length, the o6type near the posterior end of the body, a uterus primarily between the ovary and oötype and an oviduct and vitelline duct extending posteriad primarily between the uterus and dextral body margin. We emend Psettarium and provide a diagnostic key to the species. Psettarioides is regarded as a junior synonym of Psettarium because herein we return its type species, P. tropicum, to Psettarium. Regarding the three other sanguinicolids formerly of Psettarioides, we suspect that P. pseudupenei Lebedev et Parukhin, 1972 belongs to Psettarium but include it only tentatively pending an examination of type or other material; we tentatively place P. kurochkini Parukhin, 1976 in Cardicola Short, 1952; and we designate P. grandis (Lebedev et Mamaev, 1968) as incertae sedis pending examination of type or other appropriate material.

Selachohemecus benzi n. sp. (Digenea: Sanguinicolidae) from the blacktip shark Carcharhinus limbatus (Carcharhinidae) in the northern Gulf of Mexico

Selachohemecus benzi Bullard & Overstreet n. sp. infects the heart and kidney of the blacktip shark Carcharhinus limbatus in the northern Gulf of Mexico off Florida and Mississippi, USA. Specimens of S. olsoni Short, 1954, the only congener and only other named blood fluke reported from a chondrichthyan in the Gulf of Mexico, were collected from the heart of the Atlantic sharpnose shark Rhizoprionodon terraenovae from two new localities, Apalachicola Bay, Florida, and Mississippi Sound, Mississippi, USA. The new species differs from S. olsoni by having a larger body (1.4-3.8 mm long), robust tegumental body spines numbering 51-63 along each lateral body margin, a testis extending from the posterior caeca to the ovary, and a medial ovary with lobes. We amend the diagnosis of Selachohemecus Short, 1954 to accommodate it and provide a diagnostic key for all named chondrichthyan blood flukes.

Larval development of five species of blenny (Teleostei: Blenniidae) from the western central North Atlantic, with a synopsis of blennioid family characters

Light trap collections on oil and gas platforms in the northern Gulf of Mexico off Louisiana from 1995 to 1997 contained young of tessellated blenny Hypsoblennius invemar, freckled blenny Hypsoblennius ionthas, featherduster blenny Hypleurochilus multifilis, molly miller Scartella cristata and seaweed blenny Parablennius marmoreus, which are described. Interspecific differences were: number of dorsal, anal, pelvic and caudal fin elements; number of mandibular pores; presence or absence of canine teeth, hypural 5 and pectoral fin pigment; width of gill openings; length of preopercular spines (in larvae). Size at settlement differed among some taxa, but all five species settled within a narrow size window of c. 1·5 mm standard length (LS). Hypsoblennius invemar, H. ionthas, H. multifilis and S. cristata settled at mean sizes between 11·3 and 12·1 mm LS, whereas P. marmoreus settled at a mean size of 19·3 mm LS. Sexually dimorphic differences were consistently evident by 17–18 mm LS in all species but P. marmoreus. The two smallest blennies with external characters normally associated with sexual maturity were a 20 mm male and 21 mm female H. multifilis. Primary caudal fin rays began to bifurcate between 17·0 and 18·3 mm LS in H. invemar, H. ionthas, H. multifilis and S. cristata. Hypleurochilus multifilis displayed the external characteristics of being sexually mature at 20–21 mm LS. Thus, bifurcation of primary caudal fin rays was an indicator of approaching sexual maturity in H. multifilis and this may also be true in the other species studied.

New Locality Records for Dermophthirius carcharhini (Monogenea: Microbothriidae) and Dermophthirius maccallumi and a List of Hosts and Localities for Species of Dermophthirius

Abstract We report Dermophthirius carcharhini (Monogenea: Microbothriidae) from the skin of a dusky shark, Carcharhinus obscurus (Carcharhinidae), in the southwest Indian Ocean off Umhlanga Rocks, South Africa, and Dermophthirius maccallumi from the skin of 2 bull sharks, Carcharhinus leucas, in the northern Gulf of Mexico off Cat Island, Mississippi, U.S.A. No previous report exists of a microbothriid from the western Indian Ocean or from off southern Africa or of D. maccallumi from beyond the vicinity of the Lake Nicaragua–San Juan River system. We also provide a list of hosts and localities for members of Dermophthirius.

The oxygen isotopic record of seasonality in Conus shells and its application to understanding late middle Eocene (38 Ma) climate

To better understand Eocene climate and the isotopic record of paleotemperature preserved in shells of the gastropod Conus, we serially sampled and analyzed four modern and two Eocene shells from the U.S. Gulf Coast and the Gulf of Mexico. The modern shells are from nearshore Mexico off Veracruz, off-shore Texas (Stetson Bank), and nearshore Florida (Alligator Point). The fossil shells are of late middle Eocene (ca. 38 Ma) age from the Moodys Branch Formation in Mississippi (U.S.A.). The four modern shells yield three different oxygen-isotopic patterns of seasonality (asymmetrical saw-tooth, cuspate, and irregular) representing different seasonal growth patterns and environments. The asymmetrical sawtooth pattern occurs in the middle shelf specimen (Stetson Bank) and indicates rapid spring and declining autumn growth, presumably in response to increased nutrient supply and productivity associated with spring upwelling. The cuspate pattern indicates winter shutdown and occurs in the most northern specimen. The irregular pattern reflects seasonal freshwater input in a nearshore environment. The Eocene shells yield an asymmetrical sawtooth pattern suggestive of enhanced spring growth during upwelling.Assuming a constant seawater δ18O of 0.24‰ (Lear et al., 2000), including correction for latitude (Zachos et al., 1994), oxygen isotope data yield a mean annual range of temperature (MART) for the late middle Eocene of 4–5°C, and a mean annual temperature (MAT) of 23°C. Taking the depth estimation (20–100 m) into consideration, sea surface temperatures are estimated to be >25°C for summer, ∼21°C for winter, and MAT of >23°C. Compared with modern temperatures and isotopic paleotemperatures of modern shells, the late middle Eocene Gulf Coast experienced warmer winter temperatures. The difference between modern and late middle Eocene climate can partly be attributed to the development of a continental cold front during the modern winter, and to the increased marine influence during the middle Eocene caused by the warmer water mass of the ocean.

Statolith age validation and growth of Loligo plei (Cephalopoda: Loliginidae) in the north-west Gulf of Mexico during spring/summer

Statolith validation and age and growth analysis was undertaken for the loliginid squid Loligo plei in the north-west Gulf of Mexico off Galveston, Texas. Statolith increments were shown to be laid down daily based on tetracycline staining of 19 individuals maintained in captivity. Ageing of field-captured individuals from late summer revealed that this species has rapid growth rates and a life span of about five months at least during the warm period of the year in this region of the Gulf of Mexico.

LONG DISTANCE OFFSHORE MOVEMENTS OF BOTTLENOSE DOLPHINS1

AbstractDespite recent progress defining the morphological and genetic characteristics of forms of the bottlenose dolphin inhabiting offshore waters, little is known of their behavior or ranging patterns. Reports suggest that an “offshore form” exists between the 200‐ and 2,000‐m isobaths in distinct Gulf of Mexico and western North Atlantic stocks, while one or more coastal forms inhabit the waters inshore. Two opportunities to track rehabilitated adult male bottlenose dolphins with satellite‐linked transmitters occurred in 1997. “Rudy” stranded in NW Florida and was released in the Gulf of Mexico off central west Florida. He moved around Florida and northward to off Cape Hatteras, NC, covering 2,050 km in 43 d. “Gulliver” stranded near St. Augustine and was released off Cape Canaveral, FL. He moved 4,200 km in 47 d to a location northeast of the Virgin Islands. Gulliver swam through 5,000‐m‐deep waters 300 km offshore of the northern Caribbean islands, against the North Equatorial Current. These records expand the range and habitat previously reported for the offshore stock of bottlenose dolphins inhabiting the waters off the southeastern United States, underscore the difficulties of defining pelagic stocks, illustrate the success of rehabilitation efforts, indicate the value of follow‐up monitoring of rehabilitated and released cetaceans, and expand our understanding of the long‐range movement capabilities of a dolphin species more commonly thought of as a resident in coastal waters.

Marine inundated archaeological sites and paleofluvial systems: examples from a karst‐controlled continental shelf setting in Apalachee Bay, Northeastern Gulf of Mexico

Underwater geoarchaeological research in Apalachee Bay, in the northeastern Gulf of Mexico off northwest Florida, has enabled the reconstruction of portions of the karst-controlled paleodrainage system, the discovery of several inundated prehistoric archaeological sites, and the exposure of sediments accumulated during the drowning of the continental shelf. Diagnostic artifacts discovered at the sites included chipped stone tools and debitage indicating Paleoindian, Early Archaic, and Middle Archaic occupation. A geoarchaeological model using terrestrial analogs was used to locate and investigate inundated sites. Methods employed include seismic profiling, vibracoring, diver tow surveys, diver collection transects, and induction dredge excavations. We document evidence for sea-level rise, related environmental succession and site formation processes for indundated prehistoric sites in the Apalachee Bay region from approximately 8000 to 6000 yr B.P. © 1997 John Wiley & Sons, Inc.

Marine inundated archaeological sites and paleofluvial systems: examples from a karst-controlled continental shelf setting in Apalachee Bay, Northeastern Gulf of Mexico

Underwater geoarchaeological research in Apalachee Bay, in the northeastern Gulf of Mexico off northwest Florida, has enabled the reconstruction of portions of the karst-controlled paleodrainage system, the discovery of several inundated prehistoric archaeological sites, and the exposure of sediments accumulated during the drowning of the continental shelf. Diagnostic artifacts discovered at the sites included chipped stone tools and debitage indicating Paleoindian, Early Archaic, and Middle Archaic occupation. A geoarchaeological model using terrestrial analogs was used to locate and investigate inundated sites. Methods employed include seismic profiling, vibracoring, diver tow surveys, diver collection transects, and induction dredge excavations. We document evidence for sea-level rise, related environmental succession and site formation processes for indundated prehistoric sites in the Apalachee Bay region from approximately 8000 to 6000 yr B.P. © 1997 John Wiley & Sons, Inc.

New fanworm species (Polychaeta: Sabellidae: Fabriciinae) in the genusPseudofabriciolaFitzhugh

Three new species are described: Pseudofabriciola quasiincisura from Belize, P. peduncula from Papua New Guinea, and P. sofla from the Gulf of Mexico off Florida. The total number of species in the genus is increased to 11. Pseudofabriciola quasiincisura and P. peduncula are intertidal, whereas P. sofla is from 26 m depth. An additional species from the Gulf of Mexico off Florida (88m depth), known only from a single specimen lacking the branchial crown, is described briefly but not named. Pseudofabriciola sofla and the unnamed species were originally described by Uebelacker (1984) as Fabricia sp. A. An emended definition for Pseudofabriciola is provided. Cladistic relationships of the species described herein are evaluated relative to others in the genus. The depth distribution of Pseudofabriciola, which displays the greatest known range within the Fabriciinae, is also re-examined.

TRACKING BUOYS FOR OIL SPILLS

ABSTRACT The use of tracking buoys in oil spill response, planning, and training and criteria for the selection of these buoys were studied in conjunction with an experiment conducted in the Gulf of Mexico during March 1994 on the relative motions of several oil spill drifter buoys. For the test, wood chips and cottonseed hulls were used to simulate the motion of the oil. Six different types of buoys and three different positioning and tracking systems, in various combinations, were tested. The first day of the program was conducted in Galveston Bay, the second in the Gulf of Mexico off Galveston. Significant differences were noted in the movements of the various buoys. Analysis of the data from these experiments suggests that tracking of the buoys should occur for a longer time period than in the experiments in order to reduce the influence of positioning errors.

Spermatophore Structure and Anatomy of the Ejaculatory Duct in Penaeus setiferus, P. duorarum, and P. aztecus (Crustacea: Decapoda): Homologies and Functional Significance

Spermatophore Structure and Anatomy of the Ejaculatory Duct in Penaeus setiferus, P. duorarum, and P. aztecus (Crustacea: Decapoda): Homologies and Functional Significance

Effects of hypoxia on continental shelf benthos: comparisons between the New York Bight and the Northern Gulf of Mexico

Abstract Depletion of dissolved oxygen to a point inducing mortality of bottom dwelling organisms (hypoxia) occurs in several continental shelf environments in Europe and North America and may have increased as a result of nutrient overenrichment due to human activities. Hypoxia in coastal waters results from plankton decomposition combined with a density stratification of the water column that hinders the oxygenation of bottom waters. Mass mortalities of benthic organisms have occurred as a result of extensive hypoxia on the inner continental shelves of the New York Bight and the northern Gulf of Mexico off Louisiana and Texas. Extensive hypoxia is rare in the New York Bight, and following catastrophic hypoxia in 1976, recovery of the benthic communities took more than two years. On the Louisiana-Texas shelf, large-scale hypoxia occurs virtually every year and recovery from this disturbance is rapid, because the community is kept in an early successional state by the annually recurring hypoxia.

Zoeal development ofEthusa microphthalmasmith, 1881 (Brachyura, Dorippidae) reared in the laboratory, with a comparison of other dorippid zoeae

The complete zoeal development of a dorippid crab in the subfamily Ethusinae is described for the first time from a known parental female. The ovigerous Ethusa microphthalma was collected in the northern Gulf of Mexico off Louisiana. Larvae passed through four zoeal stages, and the megalopa was reached in 59 days at 20°C and 35 ppt salinity. The larvae differ from those of the few other dorippids for which a zoea is known. Salient distinguishing features include long lateral carapace spines, the presence of six setae on the endopod of the maxillule and maxilla, and a spinose antennal exopod lacking projecting mid-length spines or setae. Zoeal characters are compared to those known for the allied subfamily Dorippinae, and all references to zoeae of the Dorippidae are tabulated.

Sharp Reductions in Abundance of Fishes and Benthic Macroinvertebrates in the Gulf of Mexico Off Texas Associated with Hypoxia

Sharp Reductions in Abundance of Fishes and Benthic Macroinvertebrates in the Gulf of Mexico Off Texas Associated with Hypoxia

Using Nannofossil Counts in Interpretation of Subsurface Deltas: ABSTRACT

The Balize delta in Plaquemines Parish, Louisiana, and the six preceding Holocene deltas offer models for subsurface interpretation. Nannoplankton counts were made from 65 bottom samples from the shelf area of the Gulf of Mexico off Louisiana. This work indicated a correlation between surface salinity and nannoplankton counts. In the subsurface, an ecology of outer middle neritic (water depth approximately 120 ft; 37 m) or deeper, accompanied by low (less than 5,000 per slide) nannofossil counts, indicates a deltaic environment. The Miocene Cristellaria I Hollywood and Krumbhaar sands, which were deposited by prograding deltas, are examples of nannofossil End_Page 1428------------------------------ counts applied to subsurface deltaic interpretation. The major hydrocarbon reserves at the Hollywood and Houma fields are attributed to thick prodelta shale (low nannofossil counts) prior to sand deposition. This thick shale triggered faults and diapiric structures that were timed perfectly for receiving the early-migrating hydrocarbons. The Hollywood and Krumbhaar deltas prograded over the thick shale depositing distributary-mouth bar sands. Accumulation in the Krumbhaar sand at the Hollywood and Houma fields was controlled by the lenticular nature of the distributary-mouth bar sand. Distributary-mouth bar sand E contains most of the reserves discovered to date in the Krumbhaar sand. Perfectly timed structure, faulting, and lenticular deltaic sand are responsible for this geographic concentration of hydrocarbons in a sand covering an area of 50 by 100 m (80 by 160 km). The Krumbhaar sand was deposited by two distinct and separate deltas. The deltaic environmental setting for hydrocarbon accumulation in the Houma embayment area compares favorably with a similar Oligocene Vicksburg-Frio delta in Jefferson County, Texas. Deltaic information obtained from this study may serve as a subsurface model for discovering large reserves hidden by subtle deltaic traps. End_of_Article - Last_Page 1429------------

Environmental study: Offshore Texas

A comprehensive environmental baseline study of a 24,000‐mi2 segment of the outer continental shelf (OCS) is being conducted in the Gulf of Mexico off south Texas by the U.S. Geological Survey, the University of Texas, Texas A&M, Rice University, the National Oceanic and Atmospheric Administration, and other institutions. The area to be studied extends from the Matagorda peninsula southward to the U.S.‐Mexican boundary and seaward to the 600‐ft depth contour.The $1.5 million research effort in 1975 is a phase of an extended study known as the South Texas OCS Environmental Assessment Program, funded by the Interior Department's Bureau of Land Management and aimed primarily at gathering environmental baseline data prior to exploratory drilling to be undertaken after the scheduled lease sale for the south Texas outer continental shelf.

Nektonic Pipefishes (Syngnathidae) from the Gulf of Mexico off Mississippi

Species composition, occurrence, and selected meristic and length frequency data are reported for 108 juvenile pipefishes collected in meter nekton nets in the Gulf of Mexico off Mississippi. The genus Syngnathus was represented by S. louisianae, S. pelagicus, S. springeri, S. elucens, and S. f. floridae. Amphelikturus dendriticus is recorded for the first time from the Gulf of Mexico and offshore distribution of these pipefishes is discussed.

A Study of Nektonic and Benthic Faunas of the Shallow Gulf of Mexico Off the State of Mississippi As Related to Some Physical, Chemical, and Geological Factors

A Study of Nektonic and Benthic Faunas of the Shallow Gulf of Mexico Off the State of Mississippi As Related to Some Physical, Chemical, and Geological Factors