Variaciones morfológicas de la concha del mejillón choro, Modiolus capax, en dos poblaciones silvestres del suroeste del Golfo de California: Morphological variations of horsemussel shell, Modiolus capax, in two wild populations at southwestern Gulf of California

La forma y crecimiento de la concha de los moluscos bivalvos varía entre y dentro de cada especie, en respuesta a numerosos factores bióticos y abióticos. Se evaluaron los índices biométricos y relaciones morfométricas de la concha de dos poblaciones del mejillón Modiolus capax en el suroeste del Golfo de California. Se colectaron 60 mejillones de Santa Rosalía (SR) y Bahía de La Paz (LP) en cada estación anual, desde verano 2019 a verano 2020. La temperatura del agua, oxígeno disuelto, pH, profundidad y transparencia se determinaron en cada muestreo por localidad. Los mejillones de SR fueron más grandes y pesados, con la forma de su concha más compacta y convexa. Las interacciones morfométricas de las dimensiones de la concha para las dos poblaciones fueron lineales. Las relaciones de la altura/longitud y altura/ancho de la concha resultaron en un crecimiento relativo de tipo alométrico positivo, mientras que la longitud/ancho de la concha presentó alometría negativa. El mayor coeficiente de correlación se obtuvo para la interacción altura/ancho de la concha en ambas poblaciones. La interacción más fuerte en SR y LP se encontró durante invierno 2019 y otoño 2019, respectivamente. Las relaciones morfométricas para el total de las poblaciones mostraron el mismo patrón que las obtenidas por estación anual. Los resultados revelan diferencias en talla, morfología y morfometría de la concha entre las dos poblaciones de M. capax, lo que refleja una situación de estrés y/o adaptación de la especie a las condiciones de cada lugar

Heavy-metal contents in oysters (Crassostrea gigas) cultivated on the southeastern coast of the Gulf of California, Mexico

Background. For its flesh and flavor, the Pacific oyster Crassostrea gigas is cultivated worldwide, but as filter feeders, this bivalve bioaccumulates heavy metals from different pollution sources, rendering them unsafe for human consumption. Goals. We carried out this study to assess the heavy metal concentrations in cultivated oysters from a farm located on the southeastern coast of the Gulf of California during 2011. Methods. Oyster samples were analyzed monthly (March- December 2011) for cooper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), arsenic (As), and mercury (Hg). Results. The mean values (?g g-1, dry weight) for each metal were Cu = 51.42 ± 25.92, Cr = 24.97 ± 32.38, Cd = 13.84 ± 4.22, Ni = 10.26 ± 12.18, Pb = 2.18 ± 1.28, As = 0.37 ± 0.08, Zn = 267.42 ± 92.29, and Hg = 0.02 ± 0.01.Conclusions. The results suggest that metal burdens could be influenced by anthropogenic activities such as agriculture and aquaculture surrounding the culture zone. Cu, Cr, Cd, and Pb levels (?g g-1, fresh weight) were above the maximum permissible values and thus pose a threat to human health. Metal concentrations must be monitored periodically.Background. For its flesh and flavor, the Pacific oyster Crassostrea gigas is cultivated worldwide, but as filter feeders, this bivalve bioaccumulates heavy metals from different pollution sources, rendering them unsafe for human consumption. Goals. We carried out this study to assess the heavy metal concentrations in cultivated oysters from a farm located on the southeastern coast of the Gulf of California during 2011. Methods. Oyster samples were analyzed monthly (March- December 2011) for cooper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), arsenic (As), and mercury (Hg). Results. The mean values (?g g-1, dry weight) for each metal were Cu = 51.42 ± 25.92, Cr = 24.97 ± 32.38, Cd = 13.84 ± 4.22, Ni = 10.26 ± 12.18, Pb = 2.18 ± 1.28, As = 0.37 ± 0.08, Zn = 267.42 ± 92.29, and Hg = 0.02 ± 0.01.Conclusions. The results suggest that metal burdens could be influenced by anthropogenic activities such as agriculture and aquaculture surrounding the culture zone. Cu, Cr, Cd, and Pb levels (?g g-1, fresh weight) were above the maximum permissible values and thus pose a threat to human health. Metal concentrations must be monitored periodically

Prevalencia de Perkinsus sp. (Apicomplexa) en la almeja chocolata Megapitaria squalida de la costa central de Sinaloa, México

Background. Different species of Perkinsus spp. have been associated to mortality of commercial mollusks. Goals. The prevalence of Perkinsus sp. in the callista clam Megapitaria squalida was evaluated monthly (June 2015 to November 2016) to determine the relationship between the infection and size of clam. Methods. 5,000 clam seeds (5.73 mm height of the shell and 0.03 g of initial weight) were placed in a fishing refuge of Altata, Sinaloa. A total of 60 specimens were collected each month to evaluate their growth and parasite prevalence. The water physicochemical parameters (temperature, salinity, pH, dissolved oxygen, depth, and transparency) and the length, height, and width of the shell and final weight of M. squalida were obtained. Results. Ray’s thioglycollate fluid medium test (MFTR) detected spherical cells (10X) of dark color indicating the presence of presumed hypnospores of Perkinsus sp. during the first 17 months of sampling. The mean infection intensity was grade 2 (mild), while the maximum prevalence was 43.33% in the months of November (2015) and March (2016), with an average of 21.05%. None of the Perkinsus sp sample (n = 112) positively detected by MFTR confirmed the presence of the protozoan. There was no correlation (p >0.05) between the prevalence of the pathogen with all the parameters studied. Conclusions. The results suggest that M. squalida is not susceptible to Perkinsus sp. The present represents the first report of Perkinsus sp. In the callista clam M. squalida.Antecedentes: Diferentes especies del protozoario Perkinsus spp. han sido asociados con mortalidades de moluscos comerciales. Objetivos: Se evaluó la prevalencia de Perkinsus sp. en la almeja Megapitaria squalida (junio 2015 a noviembre de 2016) para determinar la relación de la infección con la talla. Métodos: Se sembraron 5,000 semillas (5.73 mm altura de la concha y 0.03 g de peso inicial) en un refugio pesquero de Altata, Sinaloa. Se recolectaron 60 ejemplares cada mes para evaluar su crecimiento y prevalencia del parasito. Se obtuvieron los parámetros fisicoquímicos del agua (temperatura, salinidad, pH, oxigeno disuelto, profundidad y transparencia) y la longitud, largo y ancho de la concha y peso final de M. squalida. Resultados: La prueba de medio fluido de tioglicolato de Ray (MFTR) detecto células esféricas (10X) de color obscuro, indicando la presencia de presuntas hipnosporas de Perkinsus sp. durante los primeros 17 meses de muestreo. La intensidad de la infección promedio fue de grado 2 (leve), mientras que la prevalencia máxima fue de 43.33% en los meses de noviembre (2015) y marzo (2016), con un promedio de 21.05%. Ninguna de las muestras positivas (n = 112) de Perkinsus sp. con MFTR confirmo la presencia del protozoario. No se obtuvo correlación (p >0.05) entre la prevalencia del patógeno con todos los parámetros estudiados. Conclusiones: Los resultados sugieren que M. squalida es poco susceptible a la infección de Perkinsus sp. El presente trabajo representa el primer reporte de Perkinsus sp. en la almeja chocolata M. squalida

Morphometric relationships of the siphon clam Panopea globosa (Bivalvia: Hiatellidae) in the southeasternmost of the Gulf of California, Mexico

Abstract. The morphometric relationships of the siphon clam Panopea globosa from Sinaloa, Mexico, were analyzed from February 2014 to April 2015. A total of 370 specimens were collected, measured (shell length, width, and height) and weighed (body weight, tissue weight, and shell weight). The coefficient of determination indicated variation in the fitting of morphometric variables among measured traits. The type of relative growth for all morphometric relationships was negative allometry. This is the first report on morphometric relationships of P. globosa from Sinaloa, Mexico

Morphometric relationships of the siphon clam Panopea globosa (Bivalvia: Hiatellidae) in the southeasternmost of the Gulf of California, Mexico

The morphometric relationships of the siphon clam Panopea globosa from Sinaloa, Mexico, were analyzed from February 2014 to April 2015. A total of 370 specimens were collected, measured (shell length, width, and height) and weighed (body weight, tissue weight, and shell weight). The coefficient of determination indicated variation in the fitting of morphometric variables among measured traits. The type of relative growth for all morphometric relationships was negative allometry. This is the first report on morphometric relationships of P. globosa from Sinaloa, Mexico

Modelando el crecimiento individual de la ostra japonesa Crassostrea gigas cultivado en el Golfo de California mediante el modelo de von Bertalanffy

This study demonstrate the advantage of multi-model approach to calculate the growth of Crassostrea gigas cultivated in the Gulf of California. The generalized von Bertalanffy growth model (VBGM) and its modification to represent the seasonal variations (VBGM seasonal) were tested. The parameters of each model and their confidence intervals were computed using the maximum-likelihood method. The best-fitting model was selected using the Akaike information criterion (AIC). According to the AIC, the VBGM seasonal best described the growth of the C. gigas. The conclusion was that C. gigas exhibits a seasonal growth pattern under the cultivation conditions of the present study.This study demonstrate the advantage of multi-model approach to calculate the growth of Crassostrea gigas cultivated in the Gulf of California. The generalized von Bertalanffy growth model (VBGM) and its modification to represent the seasonal variations (VBGM seasonal) were tested. The parameters of each model and their confidence intervals were computed using the maximum-likelihood method. The best-fitting model was selected using the Akaike information criterion (AIC). According to the AIC, the VBGM seasonal best described the growth of the C. gigas. The conclusion was that C. gigas exhibits a seasonal growth pattern under the cultivation conditions of the present study

Obtención de masas ovígeras del caracol lancetilla, Strombus pugilis (Mesogastropoda: Strombidae) en condiciones de laboratorio

Se determinó la supervivencia, reproducción y el desarrollo embrionario del caracol Strombus pugilis, por un periodo de diez meses en condiciones de laboratorio. Siete progenitores fueron recolectados en Isla Contoy, Quintana Roo, México y posteriormente trasladados al laboratorio donde fueron colocados en acuarios de 80 l con agua de mar y alimentados con alimento granulado. Un total de 30 masas ovígeras fueron recolectadas, lográndose un aumento en el número de masas de huevos en abril. La longitud total estimada de una sola masa ovígera fue de 11.24 m, el número promedio de embriones encontrados en 2 cm fue de 264, obteniéndose un total de 157 500 embriones en toda la masa de huevos. Los resultados promedio de los parámetros físico-químicos a lo largo del periodo de estudio fueron los siguientes: salinidad de 37.5±0.5 ‰, pH 7.5±0.5 y temperatura de 28±0.2 °C. Con los datos aportados en este estudio se infiere que este sistema de mantenimiento y recirculación de los progenitores es excelente tanto para la reproducción como para la obtención de las masas ovígeras en condiciones controladas.Obtaining of egg masses of the snail, Strombus pugilis (Mesogastropoda: Strombidae) under laboratory conditions. The survival, reproduction and embryonic development of Strombus pugilis, were determined during a period of ten months under laboratory conditions. Seven progenitors were collected in Contoy Island, Quintana Roo, Mexico and later transferred to the laboratory, where they were placed in aquarium with 80 l of sea water and fed with "pellets". A total of 30 egg masses were collected, one on September and the other on April. The estimated total length of one egg mass was 11.24 m; the mean number of embryos obtained per 2 cm was 264, obtaining an estimated total of 157 500 embryos in the egg mass. The means of the physical-chemical parameters during the study were: salinity 37.6±0.5 ‰, pH 7.5±0.5 and temperature 28±0.2 °C. The maintenance and water recirculation system used to sustain the breading stock is excellent both for reproduction of the organism and for obtaining egg masses under controlled conditions. Rev. Biol. Trop. 55 (1): 183-188. Epub 2007 March. 31

Obtención de masas ovígeras del caracol lancetilla, Strombus pugilis (Mesogastropoda: Strombidae) en condiciones de laboratorio

Se determinó la supervivencia, reproducción y el desarrollo embrionario del caracol Strombus pugilis, por un periodo de diez meses en condiciones de laboratorio. Siete progenitores fueron recolectados en Isla Contoy, Quintana Roo, México y posteriormente trasladados al laboratorio donde fueron colocados en acuarios de 80 l con agua de mar y alimentados con alimento granulado. Un total de 30 masas ovígeras fueron recolectadas, lográndose un aumento en el número de masas de huevos en abril. La longitud total estimada de una sola masa ovígera fue de 11.24 m, el número promedio de embriones encontrados en 2 cm fue de 264, obteniéndose un total de 157 500 embriones en toda la masa de huevos. Los resultados promedio de los parámetros físico-químicos a lo largo del periodo de estudio fueron los siguientes: salinidad de 37.5±0.5 , pH 7.5±0.5 y temperatura de 28±0.2 °C. Con los datos aportados en este estudio se infiere que este sistema de mantenimiento y recirculación de los progenitores es excelente tanto para la reproducción como para la obtención de las masas ovígeras en condiciones controladas

Modeling the individual growth of the Pacific oyster Crassostrea gigas cultivated in the Gulf of California using the von Bertalanffy model

This study demonstrate the advantage of multi-model approach to calculate the growth of Crassostrea gigas cultivated in the Gulf of California. The generalized von Bertalanffy growth model (VBGM) and its modification to represent the seasonal variations (VBGM seasonal) were tested. The parameters of each model and their confidence intervals were computed using the maximum-likelihood method. The best-fitting model was selected using the Akaike information criterion (AIC). According to the AIC, the VBGM seasonal best described the growth of the C. gigas. The conclusion was that C. gigas exhibits a seasonal growth pattern under the cultivation conditions of the present study