Marcial Villalejo-Fuerte

BIOCHEMICAL COMPOSITION AND ITS RELATIONSHIP WITH THE GONADAL INDEX OF THE BLACK OYSTER HYOTISSA HYOTIS (LINNAEUS, 1758) AT ESPIRITU SANTO GULF OF CALIFORNIA

Abstract The monthly variation in the biochemical composition of the digestive gland, the adductor muscle and the gonad and its relationship with the gonadal index (GI) were studied during 2 years in a wild population of Hyotissa hyotis living in the Gulf of California. Protein was the main constituent of the gonad, digestive gland and adductor muscle. Temperature (20°C to 24°C) favored the accumulation of protein in the muscle during gametogenesis. Carbohydrates and lipids were stored in the gonad, digestive gland and adductor muscle during the spring gametogenesis to support the reproduction effort. Three spawning periods were detected, one in the first year and two during the second.

Ciclo reproductivo del pargo lunarejo Lutjanus guttatus (Steindachner, 1869) en las costas de Guerrero, México

Se establecio el ciclo reproductivo del pargo lunarejo Lutjanus guttatus, un pez de gran importancia comercial. Los organismos se recolectaron mensualmente desde febrero de 1993 a diciembre de 1994. La proporcion de sexos poblacional fue de 1M:0.96H y no se encontro una diferencia significativa (P£0,05) de la proporcion esperada de 1:1. Las gonadas se analizaron histologicamente y se describieron las fases de desarrollo gonadal. L. guttatus presenta un desarrollo asincronico de las gonadas y es un desovador parcial. La actividad reproductiva estuvo presente todo el ano aunque con dos periodos reproductivos principales (marzo-abril y agosto-noviembre) representados por altos porcentajes de gonadas categorizadas como maduras y en desove. Estos periodos coinciden con valores elevados del indice gonadosomatico (IGS) y valores bajos del indice hepatosomatico (IH). El factor de condicion (FC) presento una tendencia similar a la del IGS con los maximos valores durante la epoca de reproduccion y disminuyendo hacia las epocas de reposo. Se considera que el IGS representa adecuadamente la actividad reproductiva y que puede haber una relacion inversa entre la actividad reproductiva y el IH.

REPRODUCTIVE PATTERN OF THE SQUALID CALLISTA MEGAPITARIA SQUALIDA FROM NORTHWESTERN MEXICO

Abstract The annual reproductive cycle of the squalid callista Megapitaria squalida living in the Ojo de Liebre lagoon was analyzed from January to December 2001. The reproductive activity was analyzed qualitatively (through histological analysis), defining five gonad development stages (undifferentiated, developing, ripe, spawning and spent). A quantitative analysis was also conducted (through the gonadic index and oocyte diameter) to correlate the reproductive activity with water temperature and salinity. Male and female gonads developed and spawned in parallel through time. M. squalida displays a clearly seasonal reproductive cycle in the Ojo de Liebre lagoon, with a long reproductive activity period (January to August) that coincides with the rise in temperature, plus a well defined inactivity period (September to December) with 100% of undifferentiated or spent organisms and the onset of which coincides with the temperature decrease. M. squalidas reproductive cycle does not seem to be influenced by salinity variations in the Ojo de Liebre lagoon. The spawning size of M. squalida was determined at 92 mm SL at an approximate age of 2.2 y. However, some individuals started spawning at 64 mm SL. Marked differences were found in some aspects of the reproductive pattern of M. squalida compared with studies conducted in other sites, and the likely causes are discussed here.

Fecundidad y proporción de sexos de Panulirus inflatus en la costa occidental del Golfo de California, México

The fecundity and sex ratio of P. inflatus were studied in the western coast of the Gulf of California, Mexico. From February 2004 to January 2005, 567 lobst...

GUT CONTENT, PHYTOPLANKTON ABUNDANCE AND REPRODUCTIVE SEASON IN THE BLACK OYSTER (HYOTISSA HYOTIS, LINNÉ, 1758) AT ISLA ESPÍRITU SANTO, GULF OF CALIFORNIA

Abstract Hyotissa hyotis specimens were collected at Espíritu Santo Island, Gulf of California, from March 1998 to March 1999. Water temperature was recorded, gut-content samples were obtained, phytoplankton abundance was estimated, and the reproductive status was inferred through the gonadic index. Gut content included phytoplankton, mostly diatoms (86.5%) and dinoflagellates (13.5%). The highest phytoplankton frequency in gut contents occurred from March to May, along with a growing phytoplankton abundance in seawater, matching the period of gonad development and the seasonal rise in temperature. Phytoplankton comprised diatoms (73.3%), dinoflagellates (10.4%), nannoplankton (18.8%), cyanobacteria (3.3%), and silicoflagellates (2.2%). The gonadic index suggests that this population has an annual reproductive pattern. Gonad development takes place from March to April, with the population ripening between April and July, matching the seasonal temperature rise from 22 °C to 27 °C, and spawning from July to September when temperatures reach a peak between 27 °C to 29 °C. From October onwards the population enters a postspawning and reproductive-inactivity phase.

Ciclo reproductivo de Anadara tuberculosa (Sowerby, 1833) (Arcidae) en Bahía Magdalena, México

The reproductive cycle of Anadara tuberculosa (Sowerby, 1833) and its relationship with temperature and food availability in Magdalena Bay, Mexico was studied. Twenty five adult specimens were collected, on a monthly basis, between January 1998 and February 1999. Gonads were processed by routinary histology. The reproductive cycle was divided in five stages: resting, developing, ripe, spawning and spent. The developing stage was found within the interval March-October and December 1998, and also in February 1999. Spawning was observed within intervals: January-April and June-December 1998, reaching the highest frequencies in: January (60%), September (60%), and December (71.4%). Ripeness occurred within periods: January-March and June- December 1998, reaching the highest frequencies in July (70%) and August (57.8%). A significant relationship was found between temperature and ripe stage. The annual mean concentration of chlorophyll a was 2.8 mg m -3 , the lowest concentrations were 0.5 mg m -3 (January) and 0.8 mg m -3

REPRODUCTION OF THE BLUE LOBSTER PANULIRUS INFLATUS (BOUVIER, 1895) AT “BAHÍA DE LORETO” NATIONAL PARK, GULF OF CALIFORNIA

Abstract The reproductive season and first-maturity size of the blue lobster Panulirus inflatus were determined at the “Bahía de Loreto” National Park, Gulf of California. Two hundred fifty-six females were analyzed, finding that the onset of gamete development took place in February. The incubation season started in April and ended in November. The highest percentage of ovigerous females was observed in October (88.9%). Histological analysis of gonads revealed two peaks of gonad maturity, in May (75%) and August (75%). Temperature was positively correlated to the percent ovigerous females (rs = 0.85, P < 0.05) and with the percent ripe females (rs = 0.73, P < 0.05). The individual first-maturity size was 49.5 mm CL, whereas at a population level it was 80 mm CL, this being proposed as the minimum fishing size. The incubation period was estimated at 2–3 wk, and the histological evidence suggests that each female may spawn more than once and may undergo more than one incubation period during the reproductive season. The reproduction pattern at the Bahía de Loreto National Park in the Gulf of California is discontinuous, likely because the environmental conditions in this zone are more variable than in tropical regions. This feature should be taken into account by the Mexican government when regulating the exploitation of this resource in the study area.

Variación de los índices gonádico, de rendimiento muscular y de la glándula digestiva de Spondylus princeps (Gray, 1825) (Mollusca: Bivalvia) en Isla Cedros y Punta Eugenia, México

The variation of the gonadal, muscular yield and digestive gland indexes was studied in Spondylus princeps from Punta Eugenia and Isla Cedros, Mexico. Specimens were collected from March to July 1997 and from August to December 2003. Gonadal indexes from 2% to 4% suggest reproductive inactivity from March to May and from October to December. The sustained increase in the index from May to July suggests gonadal maturity (10% of the soft tissues weight in July); the index decreased from 10% to 2% from July to October, corresponding with the spawning period. The muscular yield index showed high values (45-50%) from March to June and diminished sustainedly until August, when the lowest value (37%) was attained. Muscular yield index recovered during September and October with values of 45% staying around 40% during November and December. The muscular yield suggests that during the gonadal maturity, the energy stored in the abductor muscle is not used until the spawning season. The digestive gland index showed the highest value in March and decreased lightly until June, indicating that the energetic substances stored in the digestive gland sustain together with the external food, the gonadal development from July up to September when a fast decrease of the index occurs, suggesting that reserve substances in the digestive gland and in the muscle are used during the spawning period.

Ultrastructure of Sperm Development and Mature Sperm Morphology in Spondylus calcifer and S. Princeps (Bivalvia: Spondylidae)

ABSTRACT The entire spermatogenesis process and the presence of accessory cells in sperm development in Spondylus princeps Broderip, 1833, and S. calcifer Carpenter, 1857, were described for the first time. Spermatogenesis in both species showed similar anatomical and ultrastructural features. The testis contained amoeboid somatic cells inside the acini, frequently associated with developing gametes. Overall, spermatogenesis followed the typical pattern reported for other bivalve species, except for a few specific details. In S. princeps, intercellular bridges between spermatogonia, as well as one spermatocyte with seven mitochondria were observed. Both species had mature sperm of the ect-aquasperm type, consisting of a head, which contains a spherical-pyriform nucleus and a conical acrosome bounded by two regions of different density, four spherical mitochondria and two centrioles in the middle piece; the flagellum showed a standard 9 + 2 microtubule arrangement.

Notes on the reproductive cycle of the blotchy scallop Spathochlamys vestalis (Reeve, 1853) at Isla Danzante, Gulf of California

Este trabajo documenta algunas notas sobre el ciclo reproductivo del pectinido manchado Spathochlamys vestalis (Reeve, 1853), el cual se desconoce tanto para las costas del Pacifico como del Atlantico. En el Golfo de California es abundante sobre fondos de arena gruesa y entre las espinas de la concha china Spondylus leucacanthus. Es una especie hermafrodita funcional con la porcion gonadal masculina separada de la porcion gonadal femenina. Se observo alta proporcion de individuos maduros durante diciembre de 1994 (87,5%) y en octubre de 1995 (100%). Los individuos desovados se observaron en baja proporcion. Se encontro un 5,5% en enero, cuando la temperatura del agua de fondo fue menor de 15oC y un 5,1% en abril, cuando la temperatura se incremento a 21oC. El patron reproductivo ocurrio de manera continua sin presentar una alta correlacion con la temperatura del agua de fondo. La abundancia del fitoplancton fue alta en primavera, si embargo presento una relacion negativa con el desarrollo y la madurez del pectinido (P<0,05).