Volume 16, March 2004

Seasonal Occurrence of Reef-Related Medusae (Cnidaria) in the Western Caribbean Sea

Gloria Ramos and Lourdes Segura-Puertas
Universidad Nacional Autónoma de México, Instituto de Ciencias del Mar y Limnología, Unidad Académica Puerto Morelos, PO Box 1152, Cancún, Quintana Roo 77501, México

ABSTRACT Seasonal fluctuations in composition and abundance of medusae collected in a reef lagoon of the Mexican Caribbean were analyzed. Plankton samples and hydrological data were taken monthly from January to September 1994 at 2 stations: coastal and near-reef. The highest densities of medusae were recorded in March (17,687 ind/100 m 3 ) and August (2,433 ind/100 m 3 ) at the coastal station. Medusae were less abundant at the near-reef station, but diversity indices were higher in comparison to the coastal station. Twenty-five species (24 hydroidomedusae and 1 scyphomedusa) were identified, with Linuche unguiculata (Swartz, 1788) and Eirene lactea (Mayer, 1900) being the most abundant. Linuche unguiculata was the dominant species, accounting for more than 84% of the total numbers of medusae in the coastal station and over 97% in the near-reef station. The co-occurrence of neritic and oceanic species in the reef-associated community of medusae is probably related to circulation patterns and wind regimes. Dipurena ophiogaster (Haeckel, 1879) and Sarsia eximia (Allman, 1859) were recorded for the first time in the Mexican Caribbean Sea.

Formation of a stress-induced check mark on the otoliths of juvenile fishes: implications for mesocosm studies

Thomas R. Reinert1 and Donald M. Baltz2
1 Department of Oceanography and Coastal Sciences, Louisiana State University , Baton Rouge , Louisiana 70803 USA
2 Coastal Fisheries Institute, Department of Oceanography and Coastal Sciences, Louisiana State University , Baton Rouge , Louisiana 70803 USA

ABSTRACT Daily otolith increment widths of spot Leiostomus xanthurus and spotted seatrout Cynoscion nebulosus were examined experimentally in field mesocosms for 5 to 7 days in various habitat types. Daily otolith increments were used as a surrogate for daily somatic growth so that growth prior to capture and handling could be examined. For both species, possible effects of habitat types were confounded by an overall decrease in daily increment widths during the experimental period when compared to increment widths prior to capture. Several spotted seatrout inadvertently captured during mesocosm deployment provided a means for assessing if there was a significant mesocosm effect or if capture and handling may have caused the decreased increment widths. These “volunteers” were distinguishable from experimental fish by the occurrence of a check mark on the otoliths of the experimental fish. Because experimental increment widths of “volunteers” were not different from pre-experimental widths, handling rather than caging effects appeared responsible for reduced increment widths. While there appeared to be no “mesocosm” effect, handling stress potentially affected growth longer than the 24 h acclimation period we anticipated. Short-term effects of capture and handling of wild fish for mesocosm use should be explored and accounted for in future studies.

The first larval stage of Microprosthema semilaeve (Von Martens, 1872) (Crustacea: Decapoda: Stenopodidea) obtained in the laboratory

Joel W. Martin1 and Joseph W. Goy2
1 Natural History Museum of Los Angeles County , 900 Exposition Boulevard , Los Angeles , California 90007 USA
2 Department of Biology, Harding University , Box 12251 , Searcy , Arkansas 72149-0002 USA

ABSTRACT The first larval stage of Microprosthema semilaeve (von Martens, 1872) is described from ovigerous females collected off Sombrero Key, Florida Keys, USA, and Guana Island, British Virgin Islands, Caribbean. The larvae are characterized by a broad, triangular telson bearing posterolateral spines and an “anomuran seta,” a first maxilliped that differs markedly from the very similar (to each other) second and third maxillipeds, and the presence of the first pereiopod as a swimming appendage upon hatching, as is apparently true of all stenopodidean first stage larvae. Characters of the larvae are compared to those described from the Indian Ocean by Raje and Ranade (1978) and mistakenly attributed to this same species, and to those of stenopodidean larvae described by Lebour (1941) from Bermuda plankton. Problems in identifying adult specimens of Microprosthema from the Caribbean are discussed.

Embryogenesis in the Dwarf Seahorse, Hippocampus zosterae (Syngnathidae)

James T. Wetzel 1 and John P. Wourms 2
1 Department of Biology, Presbyterian College , Clinton , SC 29325 USA
2 Department of Biological Sciences, Clemson University , Clemson , SC 29634 USA

ABSTRACT Embryogenesis of the dwarf seahorse, Hippocampus zosterae , was studied by scanning electron microscopy of a series of developmental stages. Stages ranged from initial cleavage of the egg through term embryos. Embryos hatch from their egg envelopes about midway through development, yet remain nestled in stromal chambers of vascularized epithelium within the male brood pouch until their yolk reserves are consumed. The difference in body shape between the pipefish and seahorse first becomes discernible during mid-development, just before hatching. At this stage, embryos begin to develop their characteristic prehensile tail in contrast to the straight body and typical caudal fin of most species of pipefish. Post-hatching, ‘yolk-sac' larvae have a well developed head, that is set at a right angle to the body axis, and fully formed fins. As seahorse embryos approach term, lepidotrichia calcify, and the prehensile tail is capable of muscular contraction. Dermal scutes first appear at this stage and ossify in the term embryo. The dermal armor is then fully formed and functional. At term, the yolk reserves have been depleted, and the young are released from the brood pouch as free-swimming, free-feeding miniature versions of the adults.

Morphological characteristics of the carapace of the Hawksbill turtle, Eretmochelys imbricata , from Cuban waters

Mari Kobayashi
Laboratory of Wildlife Biology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University , N18 W9, Kita-ku, Sapporo 060-0818, Japan , Phone 81-11-706-5210, FAX 81-11-706-5569, E-mail banri@vetmed.hokudai.ac.jp

ABSTRACT Hawksbill turtles, Eretmochelys imbricata (Linnaeus, 1766), from Cuban waters of the Caribbean were analyzed to determine the relationships between straight carapace length (SCL) and either straight carapace width (SCW) or body weight (Wt). The regression equations were SCW = 0.9136(SCL) 0.951 (R 2 = 0.923, n = 315) and Wt = 4.17 10–4(SCL) 2.68 (R 2 = 0.798, n = 289), respectively. The regression equations between the first costal width (C1W) and either SCW or Wt were SCW = 3.223(C1W) 0.847 (R 2 = 0.919, n = 156) and Wt = 1.416 x 10–2(C1W) 2.426 (R 2 = 0.740, n = 133), respectively. There was no difference in slopes of the C1W-SCL relationship between wild and captive raised turtles as analyzed by ANCOVA. Thus, I pooled the group data and re-calculated the C1W and SCL relationship as SCL = 4.353(C1W) 0.848 (R 2 = 0.953, n = 340). This result indicated that SCL measurements could be estimated based on C1W measurements and that the C1W-SCL relationship could be applied to captive raised or wild hawksbills. It is clear that the SCL-SCW and C1W-SCW relationships were more similar to the relationship in the hawksbill turtles from Puerto Rican waters than to those captured in Australian waters, although there was no significant geographic difference between specimens from the Caribbean and Australian waters.

A New Species of Protanaissus Sieg, 1982 (Crustacea: Tanaidacea: Peracarida), from South Florida

Kim Larsen 1 and Richard Heard 2
1 Department of Marine Biology, Texas A & M University, Galveston, Fort Crockett Campus, Galveston, Texas, 77551 USA, E-mail tanaids@hotmail.com
2 Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, Mississippi 39564 USA, E-mail richard.heard@usm.edu

ABSTRACT A new nototanaid species, Protanaissus floridensis , is described from Biscayne Bay in southeastern Florida . Specimens were collected at a depth of 7 m in muddy sand substrata with associated aquatic vegetation ( Thalassia testudinum ). Protanaissus floridensis , which represents only the 4th species referable to the genus, is the first species of Protanaissus Sieg, 1982, known from the northern hemisphere. The new species is distinguished from the other 3 species of Protanaissus by 1) the dactylus of pereopod 1 shorter than combined length of propodus and carpus, 2) the dactylus of the cheliped with proximal spine on inner margin and proximal process on outer margin, 3) the fixed finger with 3–4 distal denticles on inner margin, and 4) the uropodal exopod uniarticulated. A key distinguishing the species of Protanaissus is presented.

Stomatopoda (Crustacea: Hoplocarida) from the shallow, inshore waters of the northern Gulf of Mexico ( Apalachicola River , Florida to Port Aransas , Texas )

John M. Foster, Brent P. Thoma, and Richard W. Heard
Department of Coastal Sciences, The University of Southern Mississippi , 703 East Beach Drive , Ocean Springs , Mississippi 39564 , E-mail beachbugs@aol.com (JMF), brent.thoma@usm.edu (BPT), richard.heard@usm.edu (RWH)

ABSTRACT Six species representing the order Stomatopoda are reported from the shallow, inshore waters (passes, bays, and estuaries) of the northern Gulf of Mexico limited to a depth of 10 m or less, and by the Apalachicola River ( Florida ) in the east and Port Aransas ( Texas ) in the west. With the exception of the “live bottom” gonodactylid, Neogonodactylus bredini (Manning), these predatory crustaceans usually inhabit burrows in mud, sand-mud, and sand substrata in coastal and shelf waters. The species treated in this paper are Neogonodactylus bredini (Manning), Lysiosquilla scabricauda (Lamarck), Bigelowina biminiensis (Bigelow), Coronis scolopendra Latreille, Squilla empusa Say, and Gibbesia neglecta (Gibbes). The questionable record of Squilla rugosa Bigelow by Archer (1948) is discussed. A review of the life history, ecology, distribution, and new northern Gulf of Mexico records is provided here for each of these species. Figures and an illustrated key are also presented.

Artificial reef matrix structures (ARMS): an inexpensive and effective method for collecting coral reef-associated invertebrates

Todd L. Zimmerman 1 and Joel W. Martin 2*
1 Long Island University , C.W. Post Campus, 720 Northern Blvd., Brookville , NY 11548-1300 USA
2 Natural History Museum of Los Angeles County, Research and Collections Branch, 900 Exposition Boulevard, Los Angeles, CA 90007 USA, *corresponding author Phone 213-763-3440, FAX 213-746-2999, E-mail jmartin@nhm.org

ABSTRACT Collecting reef-associated invertebrates usually involves disturbance of the reef area, often damaging the habitat and sometimes damaging live corals. We introduce a nondestructive, inexpensive, and effective method for collecting coral reef-associated invertebrates using approximations of small coral heads constructed of concrete, PVC pipes, nylon cleaning pads, and other materials easily obtainable in most tropical (coral-rich) countries. An example showing the effectiveness of the method is presented based on fieldwork in the eastern Caribbean .

Northern range extensions for Caprella scaura Templeton, 1836 (Crustacea: Amphipoda: Caprellidae) on the Florida Gulf coast and in South Carolina

John M. Foster 1 , Richard W. Heard 1 , and David M. Knott 2
1 Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, Mississippi 39564 USA, E-mail beachbugs@aol.com , richard.heard@usm.edu
2 Southeastern Regional Taxonomic Center, Marine Resources Research Institute, South Carolina Department of Natural Resources, Charleston, South Carolina 29422-2559 USA, E-mail knottd@mrd.dnr.state.sc.us

ABSTRACT Previous northwestern Atlantic records for the caprellid amphipod Caprella scaura Templeton, 1836 were confined to St. Croix (US Virgin Islands ), St. Barthélemy, and Puerto Rico , islands bordering the northern Caribbean Sea . Based on recent collections, C. scaura is now reported from the Gulf of Mexico (St. Andrew Bay, Florida) and the US east coast ( Charleston Harbor , South Carolina ). These constitute the first records for this apparently non-indigenous species in waters of the continental eastern United States , establishing considerable northern range extensions for C. scaura in the northwest Atlantic .

Trophic Comparison of Two Species of Needlefish (Belonidae) in the Alvarado Lagoonal System , Veracruz , Mexico

Daniel Arceo-Carranza, Jonathan Franco-López, Gretchen L. Waggy 1 , and Rafael Chavez-López
Laboratorio de Ecologia, Facultad de Estudios Superiores Iztacala, University Nacional Autonóma de México, Av. de los Barrios No 1, Los Reyes Iztacala, Tlalnepantla, México C.P. 54090 A.P. México
1 Department of Coastal Sciences, The University of Southern Mississippi , 703 East Beach Drive , Ocean Springs , MS 39564 USA

ABSTRACT We compared the diets of Atlantic needlefish, Strongylura marina , and redfin needlefish, Strongylura notata , in the Alvarado lagoonal system, Veracruz , Mexico , and analyzed diet breadth and trophic overlap between the species. All fishes were collected monthly from June 2000 to July 2001 at twelve sampling stations. A total of 74 intestinal tracts from S. marina were analyzed. The diet of S. marina consisted of 25 prey types with fish being the dominate prey. In eighty-nine digestive tracts examined from S. notata , the diet consisted of 29 prey types with the dominant prey including fishes, penaeid shrimp, polychaetes, and hymenopteran insects. There was moderate diet overlap ( a = 0.4903) between S. marina and S. notata in the rainy season, while there was little diet overlap between species during the “nortes” ( a = 0.1037) or dry ( a = 0.1675) season. There was reduced niche breadth in both S. marina and S. notata during the “nortes” (B A = 0.175 and 0.105, respectively) and dry (B A = 0.128 and 0.173, respectively) seasons, with niche breadth values being higher for both species during the rainy season (B A = 0.254 and 0.296, respectively).

RESUMEN Se realizó una comparación de la dieta de los belonidos, Strongylura marina y Strongylura notata , en el sistema lagunar de Alvarado , Veracruz , México, analizando la amplitud de dieta y el solapamiento trófico de ambas especies. Los organismos se colectaron mensualmente en el período de junio de 2000 a julio de 2001 en 12 estaciones de muestreo. Se analizaron 74 tractos digestivos de S. marina . La dieta de S. marina consiste de 25 tipos de presa de los cuales los peces constituyeron la presa dominante. Para S. notata se analizaron 89 tractos digestivos, la dieta de esta especie comprendió 29 tipos de presas diferentes, siendo los peces, camarón, poliquetos e himenópteros las presas dominantes para esta especie. El solapamiento trófico entre S. marina y S. notata fue moderado ( a = 0.4903) en la época de lluvias, disminuyendo en las épocas de nortes ( a = 0.1037) y secas ( a = 0.1675). La amplitud del nicho trófico para S. marina y S. notata fue baja en nortes (B A = 0.175 y 0.105, respectivamente) y en secas (B A = 0.128 y 0.173, respectivamente), siendo mayor para ambas especies en la época de lluvias (B A = 0.254 y 0.296, respectivamente).

Feeding Habits and Sexual Dimorphism of the Violet Goby, Gobioides broussoneti Lacepede (Pisces: Gobiidae), in the Estuarine System of Tecolutla , Veracruz , Mexico

Sergio Mata-Cortés, José Antonio Martínez-Pérez, and Mark S. Peterson 1
Laboratorio de Zoología, Facultad de Estudios Superiores Iztacala, University Nacional Autónoma de México, Av. de los Barriors No. 1, Los Reyes Iztacala, Tlalnepantla, México C.P. 54090 A.P. 314 Mexico
1 Department of Coastal Sciences, 703 East Beach Drive , The University of Southern Mississippi , Ocean Springs , MS 39564 USA

ABSTRACT Gobioides broussoneti were sampled in Silveña estuary, a branch of the Tecolutla estuary, Veracruz , Mexico , during 2 trips made between February 1998 and June 1999 to evaluate diet and sexual dimorphism. A total of 65 G. broussoneti ranging from 49–401 mm SL (0.7–124.2 g WW) were collected. There was a 1:1.2 sex ratio in favor of females. Seven food types were noted, with filamentous algae (25.4%) and detritus (21.3%) representing the principal food types. A 24 h feeding study revealed that this species feeds continuously throughout the day. The ovaries of all female G. broussoneti contained previtellogenic oocytes, characteristic of immature or regressed fish. In contrast, the lobular testis of the males contained late stages of spermatogenesis, suggesting that the fish examined were at the end of the reproductive season. Sexual dimorphism of G. broussoneti is distinguished by a small urogenital papilla, which is in the ventral region between the anal orifice and the anal fin origin. In the females it is short, blunt and has a yellow coloration; in males it is thin, pointed and has a smooth appearance. Only immature or regressed females were captured during this study indicating that G. broussoneti uses the Tecolutla estuary as a nursery and feeding ground. Questions about reproductive seasonality, ovarian development, and spawning of G. broussoneti need further investigation.

RESUMEN Gobioides broussoneti fue muestreado en el estuario Silveña, un brazo del estuario Tecolutla, Veracruz, México, durante 7 muestreos realizados entre febrero de 1998 y junio de 1999, para evaluar la dieta y el dimorfismo sexual. Fueron colectados un total de 65 G. broussoneti con tallas de 49–401 mm de longitud estándar y peso entre 0.7 y 124.2 g. Presentaron una proporción sexual de 1:1.2 a favor de las hembras. Siete tipos alimenticios fueron registrados; las algas filamentosas (25.4 %) y el detritus (21.3 %) representan los principales tipos alimenticios; un estudio alimenticio de 24 horas reveló que esta especie se alimenta continuamente a lo largo del día. Los ovarios de todas las hembras de G. broussoneti contienen ovocitos previtelogénicos, característicos de peces inmaduros o regresados. En contraste, el testículo lobular de los machos contenía estadios tardíos de la espermatogénesis, sugiriendo que el pez examinado se encontraba al final de la estación reproductiva. El dimorfismo sexual de G. broussoneti se distingue por una pequeña papila urogenital, que se encuentra en la región ventral, entre el orificio anal y el origen de la aleta anal. En las hembras esta es corta, achatada y de coloración amarilla; en machos es delgada, afilada y tiene una apariencia lisa. Estos resultados indican que G. broussoneti utiliza el estuario de Tecolutla como un lugar de crianza y alimentación, ya que en este estudio solo fueron capturadas hembras inmaduras o regresadas. Cuestionamientos acerca de estacionalidad reproductiva, desarrollo ovárico y desove de G. broussoneti requieren mayor investigación.

Gonadal Development and Sexual Dimorphism of Gobiomorus dormitor from the Estuarine System of Tecolutla , Veracruz , Mexico

Raquel Hernández-Saavedra, José Antonio Martínez-Pérez, Nancy J. Brown-Peterson 1 , and Mark S. Peterson 1
Laboratorio de Zoología, Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Iztacala. Av., de los Barrios No.1, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 05490 Mexico
1 Department of Coastal Sciences, The University of Southern Mississippi , 703 East Beach Drive , Ocean Springs , MS 39564 USA

ABSTRACT The bigmouth sleeper, Gobiomorus dormitor , is a benthic, euryhaline species, and is very abundant in river mouths, coastal lagoons, and sites away from marine influence from south Florida to Dutch Guyana. There are few studies of its life history, ecology, and abundance, particularly within Mexican waters. Nine trips to Tecolutla estuary, Veracruz , Mexico , were taken between October 1995 and May 1998 to estimate the gonadal development and sexual dimorphism of G. dormitor . A total of 94 individuals ranging from 15–260 mm SL and 0.05–181 g were captured. Seventy-two specimens were adults (60 females, 12 males) and 22 were juveniles that did not show external sexual dimorphism. Both juvenile and adult stages of G. dormitor were captured year-round in seagrass beds and adjacent shallow, muddy or sandy areas. This study has shown that G. dormitor are resident and undergo sexual maturation in the Tecolutla estuary. Histological evidence suggests both males and females undergo gonadal recrudescence in the estuary and have an extended reproductive season from May through November. However, it is unclear if the species actually spawns in the estuary, since females in the final stages of oocyte maturation were not captured. Additional research on the reproductive biology and ecology of this under-studied species is necessary to determine its role in tropical estuaries in the southern Gulf of Mexico . Information learned from areas in the center of its distribution may aid in conserving the species at the periphery of its range in Florida , where it is considered threatened.

RESUMEN La guavena, Gobiomorus dormitor , es una especie bentónica eurihalina y es muy abundante en las desembocaduras de los ríos, lagunas costeras y lugares fuera de la influencia marina, desde el sur de la Florida hasta la Guyana Holandesa. Hay pocos estudios de su ciclo de vida, ecología y abundancia, particularmente dentro de aguas mexicanas. Se realizaron 9 muestreos en el estuario de Tecolutla, Veracruz, México, entre octubre de 1995 y mayo de 1998, para estimar el desarrollo gonádico y el dimorfismo sexual de G. dormitor . Fueron capturados un total de 94 organismos de entre 15–260 mm de longitud patron y 0.05–181 gramos. Sesenta organismos fueron hembras y doce fueron machos; 22 peces fueron juveniles y no mostraron dimorfismo sexual externo. Ambos estadios, juvenil y adulto, de G. dormitor fueron capturados todo el año en camas de pastos y áreas adyacentes poco profundas, lodosas o arenosas. Este estudio ha mostrado que G. dormitor es residente y sufre maduración sexual en el estuario de Tecolutla. La evidencia histológica sugiere que machos y hembras sufren una recrudescencia gonádica en el estuario y tiene una estación reproductiva que se extiende desde mayo hasta finales de noviembre. Sin embargo, no está claro si esta especie desova actualmente en el estuario, desde que hembras en estadio final de maduración del ovocito no fueron capturadas. En investigaciones adicionales de la biología reproductiva y ecología de la especie en estudio, es necesario determinar su papel en estuarios tropicales del sureste del Golfo de México. La información obtenida de áreas en el centro de su distribución, puede ayudar en la conservación de la especie en la periferia de su intervalo en Florida, donde son considerados como peces amenazados.

Reproductive Biology of the Opossum Pipefish, Microphis brachyurus lineatus , in Tecolutla Estuary , Veracruz , Mexico

Martha Edith Miranda-Marure, José Antonio Martínez-Pérez, and Nancy J. Brown-Peterson 1
Laboratorio de Zoología, Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Iztacala. Av., de los Barrios No.1, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 05490 Mexico
1 Department of Coastal Sciences, The University of Southern Mississippi , 703 East Beach Drive , Ocean Springs , MS 39564 USA

ABSTRACT The reproductive biology of the opossum pipefish, Microphis brachyurus lineatus , was investigated in Tecolutla estuary, Veracruz , Mexico , to determine sex ratio, size at maturity, gonadal and brood pouch histology, reproductive seasonality, and fecundity of this little-known syngnathid. A total of 345 fish were collected between 1995–1998, with an overall sex ratio of 1:1.35 favoring females. Brooding males made up 45% of the population, resulting in an operational sex ratio of 1:2.45 heavily favoring females. All males > 90 mm SL were considered sexually mature, as this was the size at which the brood pouch was clearly developed. Females > 110 mm SL were sexually mature, and had asynchronous oocyte development. Opossum pipefish appear to have a year-round reproductive season in Tecolutla estuary, as females with vitellogenic oocytes and males with eggs in the brood pouch were captured during every month of the year. The number of eggs in the brood pouch was positively correlated with male SL (P < 0.001), and in all but 2 cases males brooded embryos from a single female. The brood pouch is not enclosed by a membrane, and each egg is embedded in a septum consisting of epithelial tissue and numerous blood vessels. Evidence from this study suggests M. brachyurus lineatus may be a sequentially polygamous species with sex-role reversal reproductive behavior, although additional research is necessary to confirm the reproductive ecology and behavior of the species.

RESUMEN Fue investigada la biología reproductiva del pez pipa Microphis brachyurus lineatus, en el estuario de Tecolutla, Veracruz, México, para determinar la proporción sexual, el tamaño de maduración, la histología gonádica y de la bolsa incubadora, la estacionalidad reproductiva y la fecundidad de este signátido poco conocido. Fueron colectados un total de 345 peces, entre 1995 y 1998, con una proporción sexual de 1:1.35 a favor de las hembras. Los machos incubadores comprenden el 45% de la población, con el resultado de una proporción sexual operacional de 1:2.45 a favor de las hembras. Todos los machos mayores a 90 mm de longitud patron fueron considerados sexualmente maduros, ya que este fue el tamaño al cual la bolsa incubadora estuvo claramente desarrollada. Las hembras mayores a 110 mm de longitud patron estuvieron sexualmente maduras y tuvieron un desarrollo asincrónico de los ovocitos. El pez pipa parece tener una estación reproductiva durante todo el año en el estuario de Tecolutla, ya que las hembras con ovocitos vitelogénicos y los machos con huevos en el saco incubador fueron capturados durante todos los meses del año. El número de huevos en la bolsa incubadora estuvo positivamente correlacionado con la longitud patron del macho (P < 0.001) y en todos, menos en 2 casos, los embriones de la bolsa incubadora del macho fueron de una sola hembra. La bolsa incubadora no está encerrada por una membrana, y cada huevo está depositado en un septo, que consiste de tejido epitelial y numerosos vasos sanguíneos. La evidencia de este estudio sugiere que M. brachyurus lineatus puede ser una especie secuencialmente polígama, con una conducta reproductiva de reversión sexual, aunque es necesario estudios adicionalales para confirmar la ecología reproductiva y comportamiento de la especie.

Reproductive Structures and Early Life History of the Gulf Toadfish, Opsanus beta , in the Tecolutla Estuary , Veracruz , Mexico

Alfredo Gallardo-Torres, José Antonio Martinez -Perez and Brian J. Lezina 1
Laboratory de Zoologia, University Nacional Autonoma de Mexico, Facultad de Estudios Superiores Iztacala, Av. De los Barrios No 1, Los Reyes Iztacala, Tlalnepantla , Mexico C.P. 54090 A.P. Mexico
1 Department of Coastal Sciences, The University of Southern Mississippi , 703 E. Beach Drive , Ocean Springs , MS 39564 USA

ABSTRACT Although the Gulf toadfish, Opsanus beta , is an abundant member of the nearshore Gulf of Mexico ichthyofaunal assemblage, little information exists regarding the ecology of the species, especially for southern Gulf of Mexico populations. We added to the existing knowledge of this species by describing the reproductive structures and examining the early life history of this species in the Tecolutla estuary, Mexico . Macro- and microscopic examination of 7 males showed spermatogenesis to be similar to other teleost species except for the occurrence of biflagellate spermatozoa. Histological examination of the male accessory gland showed 3 tissue layers, but their functions are still undetermined. We found asynchronous development of oocytes in the ovaries of 16 females, which may indicate multiple spawning over the long spawning season noted in this study. Batch fecundity estimates among females ranged from 79 to 518 mature ova with a mean ovum diameter of 3.5 mm. The above-mentioned factors along with large size at hatching, attached larval forms, and paternal care may account, in part, for the abundance of this species in highly dynamic systems.

RESUMEN Aunque el pez sapo del Golfo, Opsanus beta , es un miembro abundante del ensamble ictiofaunístico de las costas del Golfo de México, existe poca información acerca de la ecología de la especie, especialmente para las poblaciones del sureste del Golfo de México. Nosotros contribuimos al conocimiento existente de esta especie, describiendo las estructuras reproductoras y examinando las etapas tempranas del ciclo de vida de esta especie en el estuario de Tecolutla, México. El examen macro y microscópico de 7 individuos machos mostraron espermatogénesis similar al de otras especies de teleósteos, excepto por la presencia de espermatozoides biflagelados. El examen histológico de las glándulas accesorias del macho mostró una composición de tres capas de tejido, pero su función es aun indeterminada. Encontramos desarrollo asincrónico de los ovocitos de 16 hembras examinadas, que pueden indicar desoves múltiples a lo largo de la temporada de desove. La estimación de la fecundidad en las hembras examinadas presentó un intervalo de 79 a 518 huevos maduros con un diámetro de 3.5 mm. Los factores anteriores, junto con la talla grande al eclosionar, las formas larvales adheridas y el cuidado paterno, pueden responder a la abundancia de esta especie en sistemas muy dinámicos.

Helminths from Dormitator maculatus (Pisces: Eleotridae) in Alvarado Lagoon , Veracruz , Mexico , and supplemental data for Clinostomum complanatum Rudolphi, 1814 from Egretta caerulea (Aves: Ardeidae)

Jesus Montoya-Mendoza, Rafael Chávez-López 1 , and Jonathan Franco-López 1
Instituto Tecnológico del Mar No. 1, Carr. Veracruz-Córdoba Km. 12, Boca del Río, Veracruz, A.P. 68, C.P. 94290, México, E-mail jesusm@itmar1.edu.mx
1 Laboratorio de Ecología, Universidad Nacional Autónoma de México, Facultad de Estudios Superiores Iztacala. Av. de los Barrios No. 1, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 05490, México

ABSTRACT Fishes are important hosts of helminths with aquatic life stages, yet little information is available on host-parasite relationships in tropical low salinity ecosystems. In this paper we report helminth parasites of the fat sleeper, Dormitator maculatus , in the Alvarado lagoon system, Veracruz . Mexico . Four parasite species were recorded from D. maculatus , including trematode metacercariae of Clinostomum complanatum , as well as nematode larvae of Spyroxis sp. and Camallanus sp. and adults of Neochinorhynchus golvani . In addition, we obtained adult C. complanatum from the esophagus of the little blue heron, Egretta caerulea . Dormitator maculatus is a new host for all helminth species reported, and the Alvarado lagoonal system is a new location for these parasite relationships. The prevalence of the 2 most commonly occurring parasites, C. complanatum and N. golvani , was high throughout the year (> 60% and > 43%, respectively). Intensity of infection was highest for C. complanatum in May (92 worms/host) and for N. golvani in October 1993 (33.8 worms/host). The trophic position and habits of D. maculatus contributes to recruitment of trematode and nematode larval stages.