ABSTRACTS
(Volume 13, March 2001)


VERTICAL DISTRIBUTION OF LARVAL CARANGIDS IN THE SOUTHERN GULF OF MEXICO

César Flores-Coto1, Ricardo Rivas-Vega1, Faustino Zavala-García , and Jesús Sánchez-Robles2

1Universidad Nacional Autónoma de México, Instituto de Ciencias del Mar y Limnología, Apdo. Post. 70-305, México 04510 D.F., E-mail: coto@mar.icmyl.unam.mx
2Universidad Autónoma Metropolitana, Xochimilco, El Hombre y su Ambiente, Czda. del Hueso 1100, Col Villa Quietud, Coyocán, México 04960 D.F.

ABSTRACT
Vertical distribution of larval carangids of the southern Gulf of Mexico continental shelf was studied during a 10 d cruise in August 1993. Twenty-two stations were sampled using opening-closing nets of 75cm diameter and 505 µm mesh. Five water-column layers (0-6 m, 6-12 m, 12-18 m, 45-55 m, and 95- 105 m) were sampled (n = 72 plankton collections). A total of 4,123 larvae belonging to 8 taxa were collected: Chloroscombrus chrysurus (94.7%); Selar crumenophthalmus (2.6%); Caranx spp. (1 .6%); Selene setapinnis (0.51%); Decapterus punctatus (0.25%); Hemicaranx amblyrhynchus (0.19%); Trachurus lathami (0.05%), and Trachinotus falcatus (0.03%). Greatest abundances for most larvae occurred at the mid-shelf (16-70 m). Chloroscombrus chrysurus was also abundant at depths < 16 m and S. crumenophthalmus had its highest abundances in areas > 70 m. All taxa showed a similar pattern of vertical distribution, occurring only in the upper 3 sampled levels where they comprised 53.6%, 42.0%, and 4.3% of total larvae caught, respectively. Only 7 larvae were collected at deeper levels.

RESUMEN
Se estudió la distribución vertical de larvas de carangidos en la plataforma continental del sur del Golfo de México; durante un crucero de 10 días en agosto de 1993. Se muestrearon 22 estaciones usando redes de apertura-cierre de 75 cm de diámetro de boca y malla de 505 µm. Se muestreó en 5 niveles de la columna de agua (0.6 m, 6-12 m, 12-18 m, 45-55 m, y 95-105 m), obteniéndose 72 muestras. Se capturaron un total de 4123 larvas, pertenecientes a 8 taxa: Chloroscombrus chrysurus (94.7%); Selar crumenophthalmus (2.6%); Caranx spp. (1 .6%); Selene setapinnis (0.51%); Decapterus punctatus (0.25%); Hemicaranx amblyrhynchus (0.19%); Trachurus lathami (0.05%), y Trachinotus falcatus (0.03%). La mayoría de los taxa tuvieron sus mayores abundancias en la plataforma media (16-70 m). Chloroscombrus chrysurus también fue abundante en profundidades <16 m y S. crumenophthalmus tuvo sus mayores abundancias en áreas > 70 m. Todos los taxa mostraron un patrón similar de distribución vertical. ocurriendo sólo en los tres niveles superiores muestreados, donde comprendieron el 53.6%, 42.0% y 4.3% respectivamente, del total de larvas capturadas. Sólo 7 larvas fueron capturadas en los dos niveles mas profundos.
 

EFFECTS OF SALINITY ON DEVELOPMENT IN THE GHOST SHRIMP CALLICHIRUS ISLAGRANDE AND TWO POPULATIONS OF C. MAJOR (CRUSTACEA: DECAPODA: THALASSINIDEA)

K.M. Strasser1,2 and D.L. Felder1

1Department of Biology, University of Louisiana - Lafayette, P.O. Box 42451, Lafayette, Louisiana 70504-2451, USA, Phone: 337-482-5403, Fax: 337-482-5834, E-mail: felder@louisiana.edu
2Present address (KMS): Department of Biology, University of Tampa, 401 W. Kennedy Blvd. Tampa, Florida 33606-1490, USA, Phone: 813-253-3333 ext 3320, Fax: 813-258-7881, E-mail: kstrasser@alpha.utampa.edu

ABSTRACT
Salinity (S) was abruptly decreased from 35%o to 25%o at either the 4th zoeal (ZIV) or decapodid stage (D) in Callichirus islagrande (Schmitt) and 2 populations of C. major (Say). Other larvae were maintained at stable 35%o or 2S%o S throughout development. In C. islagrande, duration of ZIV did not vary among the stable salinities. However, a decrease of salinity at ZIV reduced the duration of this stage, suggesting that the S decrease could be a possible cue for acceleration of larval development. In the Gulf population of C. major duration of ZlV was significantly longer at stable 35%o S than at stable 25%o S; the latter equaled duration for larvae transferred from 35 to 25%o S at ZIV. Development in the Florida Atlantic population of C. major was variable but similar at stable 35 and 25%o S. In 2 of 3 such comparisons, larvae reared at a stable 35%o S more often molted to a 5th zoeal stage and became deformed at D than those reared at a stable 25%o S. Callichirus islagrande and the Gulf population of C. major, both of which inhabit lower salinity waters on the Louisiana coast, were more similar in larval responses to salinity than were the 2 populations of C. major. Adult habitat was a better indicator of larval response to salinity than was phylogenetic proximity.
 

ACCURATE 3-D MORPHOLOGICAL MEASUREMENT USING A STRUCTURED-LIGHT RANGE SENSOR

Robert L. Cromwell1 and Stuart G. Poss2

1Robot Vision Laboratory, School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907-1285, USA, E-mail: cromwell@ecn.purdue.edu
2Gulf Coast Research Laboratory Museum, Institute of Marine Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564, USA, E-mail: Stuart.Poss@usm.edu

ABSTRACT
A single-plane structured light-range sensor was tested to establish its usefulness in acquiring 3-D measurements of fish skulls. Twenty-one distances among 22 landmark points for each of 12 neurocrania of the scorpaenid fish Neomerinthe hemingway were taken with digital calipers, with a video-based 2-D imaging system widely used in systematic studies, and with a single-plane structured-light range sensor of inexpensive and simple design. Measures taken by 3-D sensor are highly correlated with those obtained from caliper measurement (r = 0.9995, P <<0.001), with a precision ranging from 0.08-0.43 mm. Like caliper-based measurements, they are less strongly correlated with measurements derived from projected video-imaging. Most skulls were scanned in just over 3 minutes each. Range maps, typically establishing the (x,y,z) coordinates of more than 75,000 points per scan, can be obtained in about 40-50 CPU seconds using software running on multiple platforms. Sensor data taken from different views can be merged to build a more complete 3-D reconstruction. System design, calibration, and use are discussed. By eliminating error due to perspective effects inherent in measuring from projected video images, such sensors hold considerable promise in quantifying biological shape in 3-D for comparative and functional studies.
 

UTILIZATION OF SALTMARSH SHORELINES BY NEWLY SETTLED SCIAENIDS IN A TEXAS ESTUARY

Bert W. Geary1 , Jay R. Rooker, and James W. Webb

Department of Marine Biology, Texas A&M University, 5007 Avenue U, Galveston, Texas 77551, USA
1corresponding author: Texas A&M University, 5007 Avenue U, Galveston, TX 77551, USA, Phone: 409-740-4784, Fax: 409-740-5002, E-mail: gearyb@tamug.tamu.edu

ABSTRACT
Post-settlement patterns of habitat use along saltmarsh shorelines of Galveston Bay, Texas were examined for 3 seiaenids; spotted seatrout (Cynoscion nebulosus), red drum (Sciaenops ocellatus), and Atlantic croaker (Micropogonias undulatus). Collections were made summer through fall of 1997 and 1998 using a l.5-m beam trawl hand-towed along the outside edge of salt marshes. Sciaenids were collected from tidal pass, bay, and remote tidal creek areas to assess large-scale (bay-wide) patterns of distribution and abundance. Cynoscion nebulosus were smaller and most numerous at bay stations, with densities peaking in June. Conversely, S. ocellatus were collected in higher numbers, and smaller sizes, at stations near the tidal pass, with peak densities in September. Micropogonias undulatus occurred in high numbers near both the tidal pass and remote tidal creeks, with undetectable size differences among areas and peak densities in November. Densities of C. nebulosus and S. ocellatus were greater at sites nearer the larval supply; patterns were less clear for M. undulatus. Small-scale patterns of habitat use were investigated within remote tidal creeks, with trends in density and size apparent for M. undulatus, while few C. nebulosus and S. ocellatus were collected. Interannual variability in densities occurred within and among stations, although total densities for each species were relatively similar between 1997 and 1998.
 

GASTROPOD LARVAE AND ZOOPLANKTON IN REEF-RELATED AREAS OF THE WESTERN CARIBBEAN SEA

Alberto de Jesús-Navarrete and José Juan Oliva-Rivera

Departamento de Pesquerías Artesanales, El Colegio de la Frontera Sur Unidad Chetumal, A.P. 424, Chetumal Q. Roo México, C. P. 77000, E-mail: Alberto@nicte-ha.ecosur-qroo.mx

ABSTRACT
In order to estimate the composition, distribution and abundance of zooplankton in 3 areas off the western Caribbean, samples were collected in 15 stations at South Coast and Chinchorro Bank, Mexico, and Hol-Chan Belize, from April to December 1996. Duplicate samples (2.5 m3) were collected bimonthly using a submersible pump. The pumped water was filtered through a 202 µm mesh net yielding a total of 20 zooplankton groups. Chinchorro Bank had 19 groups, South Coast had 15 groups, and Hol-Chan had 14 groups. The most abundant groups were copepods (43.1%), fish eggs (29.0%), foraminifera (12.0%), decapod larvae (5.7%), and gastropod larvae (4.3%). Twenty-seven species of gastropod larvae were identified with Natica sp. 1, Rissoina sp. 1, Cerithiopsis hero, Cerithium atratum, and Epitonium sp. l being dominant. Newly hatched veligers of Strombus gigas were collected only at Chinchorro Bank (5.7/10m-3). Zooplankton was diverse and showed marked changes during the sampling months. Chinchorro Bank had a higher number of marine zooplankters than South Coast and Hol-Chan, and this may be related to a greater oceanic influence. In spite of the environmental homogeneity, there were differences in the distribution and abundance of Strombus veligers, and this might be related to some water characteristics locally, affecting gastropod reproduction mainly in South Coast and Hol-Chan.
 

THE CHAETOGNATHA OF THE SOUTHWESTERN GULF OF MEXICO DURING APRIL-MAY, 1986

Silvia Mille-Pagaza and Jorge Carrillo-Laguna

Escuela Nacional de Ciencias Biológicas, I.P.N. Departamento de Zoología-Lab. de Ecología 11340, México, D.F., Fax: (525) 396-3503, E-mail: jcarrill@bios.encb.ipn.mx

ABSTRACT
An analysis of the distribution and abundance of Chaetognath species from the Gulf of Mexico during April-May 1986 is presented. Zooplankton samples were collected at 43 stations from the southwestern and eastern regions of Mexico's Exclusive Economic Zone in the Gulf of Mexico. Species richness and abundance were higher in the southwestern stations located on the continental slope. The rank of Importance Value (IV) shows 3 groups of species; the first group included Flaccisagitta enflata, Mesosagitta minima, Serratosagitta serratodentata, Krohnitta subtilis, Plerosagitta draco, Sagitta bipunctata, and Krohnitta pacifica which were the most widely distributed species during this period. Density data were classified and analyzed by Morisita s similarity index, depicting 2 large groups of sampling stations along with a third group made up of 5 stations. Two stations were distinct from the others because of the low species richness and because only 2 species with high densities were present. Simpson's dominance index showed low values throughout the study area. Densities of chaetognath species did not differ significantly between day and night samples.
 

TANAIDACEA (CRUSTACEA: PERACARIDA) OF THE GULF OF MEXICO. IX. GEOGRAPHICAL OCCURRENCE OF APSEUDES OLIMPIAE GUTU, 1986 WITH A REVIEW OF PREVIOUS RECORDS FOR THE GENUS APSEUDES IN THE GULF

Tom Hansknecht1 and Richard W. Heard2

1Barry A. Vittor and Associates, Inc., 8060 Cottage Hill Rd., Mobile, Alabama 36695, USA. Email: bvataxa@bvaenviro.com
2 Departrnent of Coastal Sciences, Institute of Marine Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564, USA, Phone: (228) 872-4200, Fax: (228) 872-4204, E-mail: richard.heard@usm.edu

ABSTRACT
Examination of tanaidacean specimens collected from shelf waters of the eastern Gulf of Mexico (Gulf) revealed the presence of the apseudomorph Apseudes olimpiae Gutu, 1986, whose type locality was unknown, but suspected to be Bermuda. It is now determined that the type material actually came from the northeastern Gulf. Although the specific station locality information for the type material has been lost; records indicate that specimens from the Gulf were sent to Romania for study by M. Bacescu and apparently became mixed with material from Bermuda. Based on additional material from the present study, new locality records are established for A. olimpiae in shelf waters (19-47 m) off the coasts of Alabama and northwestern Florida. The original illustrations of Gutu (1986) are reproduced to facilitate the identification of A. olimpiae and a map of its known distribution is provided. A brief review of previous records for the genus Apseudes Leach, 1814 indicates that A. olirnpiae is currently the only described species of the genus sensu stricto known with certainty from Gulf waters. The taxonomic status for Gulf specimens of another species in the A. intermedius-bermudeus complex and the "Apseudes sp. A" of Flint and Holland (1980) remain unresolved.
 

GROWTH OF CAPTIVE JUVENILE TRIPLETAIL LOBOTES SURINAMENSIS

James S. Franks1 , John T. Ogle2, J. Read Hendon1, Donald N. Barnes2, and L. Casey Nicholson2

1Center for Fisheries Research and Development, 1,2lnstitute of Marine Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564, USA, E-mail: jim.franks@usm.edu

ABSTRACT
Ear1y-juvenile tripletail Lobotes surinamensis (n = 27; range 45-115 mm TL, 0 = 73.0 mm; range 3.2-34.7 g TW, 0 = 12.9 g) captured in pelagic Sargassum algae off coastal Mississippi in mid-July 1999 were reared in a recirculating seawater system for 210 days. Fish were maintained on a natural light-dark cycle and fed to satiation 3 times per day. Water temperature ranged from 25.2° to 29.0°C and salinity was 28.0%o. All fish were measured for length and weight on days 1, 60, 135 and 210 of the study. Between these dates, mean daily TL growth rates were 2.2 mm/day, 1.2 mm/day, and 1.0 mm/day, respectively, where as 0 daily TW growth rates were 2.9 g/day. 4.3 g/day, and 7.1 g/day. Over the entire study, 0 TL and TW growth rates were 1.4 mm/day and 4.9 g/day. respectively. There was a significant correlation between length and weight vs. date of measurement. At the end of the study, specimens ranged from 272-431 mm TL (0 = 359 mm) and from 443.9-2,380.0 g TW (0 = 1,012.5 g).
 
 
MORPHOLOGY OF THE FIRST ZOEAL STAGE OF PLATYPODIELLA SPECTABILIS (HERBST, 1794) (DECAPODA, BRACHYURA, XANTHIDAE) OBTAINED IN THE LABORATORY

Adilson Fransozo1, Maria Lucia Negreiros-Fransozo1 , Joel W. Martin2, and Sandra E. Trautwein2,3
 
1Departamento de Zoologia, IB, UNESP, 18618-000, Botucatu (SP), Brazil, NEBECC (Group of Studies on Crustacean Biology, Ecology and Culture), E-mail: fransozo@ibb.unesp.br and mlnf@ibb.unesp.br
2Natural History Museum of Los Angeles County, Los Angeles, California 90007, USA
3University of California Los Angeles

ABSTRACT
Ovigerous females of the xanthid crab Platypodiella spectabilis (Herbst, 1794) were obtained from 2 widely separated localities: the Ubatuba coast (Félix Beach, São Paulo) of Brazil and Guana Island in the British Virgin Islands (BVI). First stage zoea larvae were obtained from females at both locations. Those from Brazil are described and illustrated. The first zoea bears dorsal, rostral, and lateral carapace spines, plus a well-developed and spinose antennal protopod that bears a greatly reduced exopod with 2 minute setae. This antennal morphology, along with other characters, places the species among the "Group I" xanthid zoeas of Rice (1980) and Martin (1984, 1988). Differences between larvae from Brazil and those from the BVI are minor and are attributed to within-species variation. Characters that serve to separate these larvae from those of cooccuring xanthids are presented. Comments on the distribution and size of Platypodiella spectabilis are included.
 

THE STOMATOPOD ALACHOSQUILLA FLORIDENSIS (MANNING, 1962) (CRUSTACEA, STOMATOPODA, NANNOSQUILLIDAE) REPORTED FROM GUANA ISLAND, BRITISH VIRGIN ISLANDS, WITH OBSERVATIONS ON COLOR

Joel W. Martin and Todd L. Zimmerman
 
Natural History Museum of Los Angeles County and University of California, Los Angeles, CA 90007, USA