Nurenskaya Vélez-Arellano

Gonadal Cycle of Tegula eiseni (Jordan 1936) (Mollusca: Gastropoda) in Bahía Asunción, Baja California Sur, Mexico

ABSTRACT The gonadal cycle of Tegula eiseni (Jordan, 1936) was determined on monthly samples (25–30 organisms) collected from a population in Bahía Asunción, B.C.S., from January 2006 to December 2006. The results of the histological study indicate that both males and females show stages of gametogenesis and gonad maturation throughout the year and only two major spawning events: one in spring and another in fall. The species behaved as a partial spawner, and only at certain times was total spawning observed in females. Maturation and release or spawning times seem to be closely related to seasonal temperature rises and abrupt changes in surface sea water temperature, which occur at brief intervals for several days at certain times of year.

Hermaphroditism in two populations of Chiton articulatus (Mollusca: Polyplacophora) from the eastern tropical coast of México

Through histological analyses, this study reveals an unusually high incidence of hermaphroditism in Chiton articulatus. Specimens were sampled every 30 days between September 2010 and September 2011 at two locations (Las Brisas and Jaramillo beaches, Acapulco) on the tropical eastern Pacific coast of Mexico. At both sites, hermaphroditism was found throughout the year, although in varying proportions. Higher percentages of hermaphroditism were found during the pre-spawning summer months (Las Brisas Beach 63%, Jaramillo Beach 68%). Two different kinds of hermaphroditic gonads were found, showing a preponderance of either male or female tissues but, commonly, female tissues occupied the greatest part of the gonad cross sections. Similar to other species of polyplacophorans, there was a predominance of males, although M:F sex ratios ranged from 0.7 to 4.5: 1 at Las Brisas Beach and 0.3–8: 1 at Jaramillo Beach.

Differences in Diet of Green (Haliotis fulgens) and Pink (Haliotis corrugata) Wild Abalone along the Pacific Coast of the Baja California Peninsula, Using Stable Isotope Analyses

ABSTRACT Stable isotopes (&dgr;13C, &dgr;15N) were used to assess differences in the diets of wild adult Haliotis fulgens and Haliotis corrugata. Temporal variations in the diets of these species were compared using specimens collected monthly during one annual cycle in Laguna La Bocana, whereas comparisons were made with samples taken in October 2012 in Bahía Tortugas. The two species of abalone have different feeding habits year round; H. corrugata showed a constant d15N pattern (between 9.5‰ and 10.4‰), whereas H. fulgens exhibited a seasonal &dgr;15Npattern [the lowest frequency (9.5‰) occurred in September and the highest (11.8‰) in December], which might indicate that this species fed on the resources that were available at the time. The d13C pattern showed that Laguna La Bocana had depleted values in relation to Bahia Tortugas, indicating different carbon sources. The fact that the d15Npattern of abalone was below the known food sources (macroalgae), suggests the presence of other sources in the diet of adult abalone, such as detritus or epiphytic diatoms.

Histological Validation of Morphochromatically-Defined Gonadal Maturation Stages of Green Abalone (Haliotis fulgens) Philippi,1845 and Pink Abalone (Haliotis corrugata) Wood, 1828

La determinacion de la fase de madurez es importante para identificar la temporada de desove y permitir establecer medidas de manejo pesquero para el aprovechamiento responsable de los recursos como el abulon. El presente trabajo valida histologicamente una escala de maduracion gonadica a manera de guia de identificacion, que consiste de cuatro fases morfocromaticas para hembras y machos (desarrollo, madurez, desove y reposo), y un estadio para los organismos reproductivamente inactivos (indiferenciado). Dada la similitud entre las caracteristicas morfocromaticas de Haliotis fulgens y Haliotis corrugata, la escala de maduracion gonadica puede ser utilizada indistintamente.

Histological Description of Oogenesis in Chiton virgulatus (Mollusca: Polyplacophora)

En el presente trabajo se describe la ovogenesis de Chiton virgulatus, utilizando histologia y las tecnicas de microscopia electronica de barrido y de transmision. Se identificaron tres tipos de ovocitos: i) ovocitos previtelogenicos con un diametro promedio de 50±20,5 µm, rodeados por celulas foliculares de forma alargada y un tamano de aproximadamente 5 µm, ii) ovocitos vitelogenicos inmaduros con un diametro promedio de 113±15,3 µm, este tipo de ovocitos presentan pequenas proyecciones citoplasmaticas, que indican el inicio del desarrollo del casco del ovocito. Adyacentes a cada prolongacion se presentan poros con un diametro aproximado de 0,7 µm y iii) ovocitos vitelogenicos maduros con un diametro promedio de 146±24,8 µm, las proyecciones citoplasmaticas del casco del ovocito crecen y en su parte apical adquieren la forma de un tridente, las celulas foliculares, dado el crecimiento de la prolongacion toman el aspecto bulboso y llegan a medir hasta 20 µm de longitud. La morfologia y la ultraestructura de las proyecciones del casco del ovocito vitelogenico maduro, asi como el tamano del poro en la base de las proyecciones son particulares para C. virgulatus, dichas caracteristicas podrian ser utilizadas en trabajos de taxonomia y fertilizacion.

Biochemical Changes During the Reproductive Cycle of Haliotis fulgens (Philippi, 1845) (Gastropoda: Archaeogastropoda) on the Baja California Sur West Coast

ABSTRACT This article describes the changes in the concentration of lipids, proteins, and carbohydrates in the gonad, digestive gland, foot and mantle of Haliotis fulgens over a reproductive cycle. An average of 30 specimens was collected each month between September 2011 and August 2013 from La Bocana, Baja California Sur, Mexico. The biometrics of each specimen were recorded, and gonads were processed using a standard histological method. Additionally, from February 2012 to February 2013, portions of nonfixed organs were frozen at -54°C for use in proximal analyses. This species showed gonadal development and spawning throughout the study period, with a peak in spawning from September through February, coinciding with sea surface temperatures near 20°C and the beginning of the decline in daylight. This study demonstrates that this species utilizes proteins, lipids, and carbohydrates stored in the foot during gonadal development and that lipid levels decrease in both the digestive gland and the gonad during spawning.

Diatom species diversity in the diet of healthy and sick specimens of adult Haliotis fulgens and Haliotis corrugata

Se analizo la diversidad de especies de diatomeas en la dieta de abulones azul (Haliotis fulgens) y amarillo (H. corrugata) del NW de Mexico. Esta se referencio con valores de indices de condicion y hepatogonadico (considerados como indicadores de la salud y cambios reproductivos, respectivamente) en ambas especies de abulon, incluyendo especimenes enfermos con sindrome de deshidratacion (WS). Las hipotesis enunciaban que: a) las asociaciones representadas en contenidos intestinales de H. fulgens vs. H. corrugata mostrarian una estructura tipica con muchos taxa raros y pocas especies abundantes; b) que no habria diferencia en la estructura de dichas asociaciones de diatomeas; y c) que las asociaciones de diatomeas en abulones con sindrome de deshidratacion serian similares a las de especimenes sanos. Para contrastar las hipotesis se examinaron abulones sanos, recolectados entre febrero 2012 y febrero 2013, y especimenes enfermos recolectados entre marzo y mayo 2012. Los especimenes se pesaron y se midieron para calcular los indices de condicion y hepatogonadico. Para analizar la diversidad de especies de diatomeas en contenidos intestinales de abulones se disecaron especimenes de 7 fechas de muestreo entre marzo y septiembre 2012. Las muestras de diatomeas se describieron con base en la abundancia relativa de las especies, indices de diversidad y de similitud. Para este periodo, 19 taxa de diatomeas comprendieron el 80% de las abundancias relativas; los mas abundantes fueron Cocconeis scutellum, Gomphonemopsis pseudexigua, Grammatophora gibberula, Bacillaria socialis y Striatella unipunctata. La diversidad de especies de diatomeas fue alta en todas las muestras. Estos valores y la similitud medida entre muestras indican que ambas especies de abulon se alimentaron de las mismas asociaciones de diatomeas disponibles in situ a lo largo de este periodo. Las muestras de diatomeas de especimenes enfermos representaron asociaciones similares a las de especimenes sanos. Por lo tanto, no hubo evidencias para rechazar ninguna de las hipotesis planteadas.