Seasonal pattern of the fish assemblage of El Conchalito mangrove swamp, La Paz Bay, Baja California Sur, Mexico

The seasonal changes in fish assemblage structure and the importance of El Conchalito mangrove swamp was assessed from October 1996 to August 1997. A modified stationary flume net was deployed at the swamp channel just before high tide and operated continuosly until the neap tide during the full moon. A total of 35,138 fish specimens were caught, belonging to 34 species included in 26 genera and 16 families. The fish assemblage changed with seasons, the fish assemblage had the highest species richness (21) and highest relative dominance index (0.77) in summer, but the highest Shannon diversity (2.7 bits/ind.) and Pielou evenness (0.73) in winter. Fish assemblages of summer and autumn had the highest similarity (68%), which reflects environmental changes that drives a sequential pattern in community structure between summer-autumn and autumn-winter clusters. Dominant species also showed a seasonal alternation between Eucinostomus currani (autumn), Albula nemoptera (winter) and Anchoa ischana (spring and summer) by numbers, whereas Diapterus peruvianus (autumn), Mugil curema (winter), Sphoeroides annulatus (spring) and A. ischana (summer) were the dominant species by biomass. The structural analysis of the fish community revealed four dominant species, seven common species and 23 rare species. The importance of the mangrove area of El Conchalito estuary is demonstrated based on the diversity of marine fishes that use this ecosystem as primary habitat for nursery, foraging and recruitment areas, and by its low disturbed conditions

Biovolumen ponderado; índice para estimar la contribución de especies en asociaciones de diatomeas bentónicas

With the purpose of deriving an alternative way for assessing the contribution of diatom taxa in benthic assemblages to biomass, the weighed biovolume index (WBV) is here proposed. The biovolumen (BV) was computed for taxa collected from intertidal mangrove sediments. The taxa were selected on the basis of total abundances (TA) and linear size. The TA and BV values showed an apparent inverse relation. In this way, the combined use of these variables is proposed (as WBV) as a more precise approximation to the contribution (as biomass) of each taxon in the assemblage. Thus, the WBV is computed as the product of the total abundances (TA) times the BV for each taxon, divided by the ? BV(AT) of all the taxa in the sample and expressed as percentage.Se propone el uso del biovolumen ponderado (BVP) de cada taxón, como una alternativa para medir la contribución a la biomasa, de los distintos taxa de diatomeas bentónicas de una asociación. Se determinó el biovolumen (BV) de taxa provenientes de sedimentos del intermareal en una zona de manglar; los taxa se seleccionaron con base en sus abundancias y su tamaño lineal. Los valores de BV y abundancia total (AT) mostraron una aparente relación opuesta. Consecuentemente, se propone el uso combinado de las AT y BV, en la forma de BVP, como mejor aproximación a la contribución (biomasa) de cada taxón en la asociación. Así, se definió el BVP como el producto del BV de un taxón por su abundancia, sobre la ? BV(AT) de todas las especies en la muestra, expresado en porcentaje

Crecimiento y supervivencia del mejillón Mytella strigata (Bivalvia: Mytilidae) en cultivo suspendido en la Laguna Macapule, Sinaloa, México

Growth and survival of the mussel Mytella strigata in a hanging culture method were evaluated during seven months in La Piedra estuary at the Macapule Lagoon System, Sinaloa, Mexico. Relative growth instant rate and growth were determined from six thousand seedlings (6 mm average). Relationship among total length-total weight was analyzed using a potential regression. Survival rate was biweekly evaluated by counting all those organisms alive as long with the accumulated rate throughout the culture period. In addition physical-chemical parameters were measured every 15 days. The temperature of the estuary fluctuated between 18.4 ºC to 30.2 ºC, salinity was among 28 to 40 ups and the average chlorophyll a concentration was 3.11mg · m?3. Average length of the shelf was 46.99 ± 0.26 mm and the average growth of 0.12 mm · day?1 (i.e. allometric growth). There were significative differences between total-weight throughout the culture (p < 0.05). Growth parameters evaluated were L? = 162 mm, K = 0.585 and to = ?0.123 years. Final survival rate was 81.25%. The mussell reach the commercial length at 7 months.Se evaluó el crecimiento y la supervivencia de juveniles del mejillón de barba de hacha (Mytella strigata) en un cultivo suspendido durante 7 meses en el Estero La Piedra en el Sistema Lagunar Macapule, Sinaloa, México. Se sembraron 6,000 juveniles de M. strigata de 6 mm de longitud promedio. Se determinó el crecimiento y la tasa de crecimiento instantáneo relativo, mediante la fórmula TCIR = ((Ln L2 Ln L1)/t) × 100. Se analizó la relación longitud de las valvaspeso total, con una regresión de tipo potencial de la forma Y = aXb. Se evaluó la supervivencia haciendo un recuento poblacional quincenal de todos los organismos vivos, obteniéndose los porcentajes de supervivencia quincenal y el porcentaje acumulado durante todo el periodo de cultivo. Se registraron los parámetros fisicoquímicos cada 15 días. La temperatura que se presentó en el estero fue de 18.4 ºC a 30.2 ºC, la salinidad de 28 a 40 ups y la concentración promedio de clorofila a de 3.11mg.m?3. La talla promedio de la concha fue de 46.99 ± 0.26 mm de largo y la tasa de crecimiento promedio de 0.12 mm · día?1, y de tipo alométrico. Se encontraron diferencias significativas en el peso total durante la duración del cultivo (p < 0.05). Los parámetros de crecimiento estimados fueron: L? = 162 mm, K = 0.585 y to = 0.123 años. La supervivencia de los organismos al final del cultivo fue de 81.25%. En el estero, M. strigata alcanzó la talla comercial a partir de los siete meses

Riqueza y abundancia relativa de los batoideos de la pesquería artesanal en el archipiélago Espíritu Santo, BCS, México

Background: The Gulf of California possesses a high diversity of marine ichthyofauna while representing one of the main fishing areas in Mexico. The shark and ray fishery constitute an important economic and social importance. Goals: In the present study, the richness and relative abundance was estimated (expressed as CPUE), for 15 batoids species taken by the artisanal fisheries in the southern zone of the Espiritu Santo Island, State of B.C.S. from October 2013 to December 2015. Methods: Batoids were taxonomically identified to species level, measured, sexed and weighed and species richness calculated. Catch as CPUE was standardized to 100 m of gillnet per hour (x100 as a scaling factor) and evaluated among species and at different spatial scales (season, year, season per year and month). Results: A total of 2198 individuals were captured and comprised of four orders, 10 families, 10 genera, and 15 species. The nominal capture effort used was 27560 m of bottom-set gillnet and 1763 h submerged time. Four species, Rostroraja velezi, Pseudobatos glaucostigma, Urobatis maculatus and Mobula mobular, were added to the existing ichthyofauna listing for the Espiritu Santo Island. Additionally, Mobula munkiana and Hypanus dipterurus represented the highest contribution in abundance and weight during the time of this study. The first species is currently protected by national and international laws, whereas the latter is a commercially exploited species. Conclusions: The partial overlap of the highest CPUE values recorded in the warm season, with the fishing ban and the reproductive activity of some species in summer, could contribute as a population recovery effect if the fishing effort after the ban is regulated.Antecedentes: El Golfo de California presenta una alta diversidad de organismos marinos y es una de las principales áreas de pesca en México. La pesquería de tiburones y rayas constituye una importante actividad económica con relevancia social. Objetivo: En el presente estudio se estima la riqueza y abundancia relativa (expresada como CPUE), de 15 especies de batoideos capturados por la pesca artesanal en la zona sur de la Isla Espíritu Santo, B.C.S. desde octubre del 2013 a diciembre de 2015. Métodos: Los ejemplares capturados fueron determinados taxonómicamente al nivel de especie, medidos, sexados y pesados. La riqueza específica correspondió al número total de especies capturadas durante el periodo de estudio. Los datos de CPUE fueron estandarizados a 100 metros de red por hora (x100 como factor de escalamiento) y evaluados entre especies y a diferentes escalas temporales (época, año, época por año y meses). Resultados: Se capturó un total de 2198 individuos, agrupados en cuatro órdenes, 10 familias, 10 géneros y 15 especies. El esfuerzo nominal empleado fue de 27560 metros de red y 1763 horas de remojo. Las especies Rostroraja velezi, Pseudobatos glaucostigma, Urobatis maculatus y Mobula mobular fueron adicionadas a los listados ictiofaunísticos existentes para la Isla Espíritu Santo. Mobula munkiana e Hypanus dipterurus, fueron las especies de batoideos con la mayor contribución en abundancia y peso durante el tiempo de la investigación. La primera está protegida por leyes nacionales e internacionales y la segunda es una especie aprovechada comercialmente. Conclusiones: La superposición parcial de los valores de CPUE más altos registrados en la época cálida, con la veda y la actividad reproductiva de algunas especies en verano, podría contribuir como un efecto de recuperación poblacional si se regula el esfuerzo pesquero posterior a la veda

Patrones de crecimiento y proporción de sexos de la jaiba Callinectes bellicosus (Decapoda: Portunidae)

Background: Knowledge of growth is relevant because it provides information on the local dynamics of the population. Goals: This study evaluated the growth, size structure, morphometry, and sex ratio of C. belliosus crab caught in the El Colorado lagoon, Ahome, Sinaloa, Mexico. Methods: Through size distributions and by the modal-progression method using the FISAT II program. Similarly, the growth parameters of the von Bertalanffy stationalized equation and the growth performance or Munro index (Ø) were determined from March 2012 to March 2013. Results: 3,242 organisms of C. bellicosus were captured of which 1,770 were males and 1,472 were females. The population of C. bellicosus in the lagoon ranged in size from 40 mm to 190 mm (CW), showing two similar modes for males and females (100 mm and 110 mm, respecti­vely). The relationships between CL-CW for both sexes were adjusted to a linear type model (males, CL = 0.5265CW-0.0539, R2 = 0.8058, p <0.05, females, CL = 0.581CW-0.6335, R2 = 0.7643, p <0.05). The CW-TW relationship was of potential type (males, TW = 0.561AC3.0751, R2 = 0.7968, p <0.05; females, TW = 0.0834C2.9077, R2 = 0.7589, p <0.05). In females, K = 0.90 years-1 and L∞ = 169 mm, K = 1.20 years-1 and L∞ = 178.5 mm. Conclusions: The growth curves suggest that C. bellicosus reaches its maximum length at 2.5 to 3 years. The sex ratio of 0.81 F : 1 M was significant (X2 (0.05, 11) = 19.675, X2 observada = 58.481, p < 0.05).   Antecedentes: El conocimiento del crecimiento en cualquier especie es relevante debido a que proporciona información de la dinámica local de la población. Objetivos: Evaluar el crecimiento, la estructura de tallas, la morfometría y la proporción de sexos de las jaibas C. bellicosus capturadas en la laguna El Colorado, Ahome, Sinaloa, México. Métodos: Durante el periodo de marzo de 2012 a marzo de 2013 se evaluaron las distribuciones de frecuencias de tallas y se aplicó el método de progresión modal mediante el programa FiSAT II. Asimismo, se determinaron los parámetros de crecimiento de la ecuación de von Bertalanffy y el desempeño del crecimiento o índice de Munro (Ø). Resultados: Se capturaron 3,242 organismos de C. bellicosus, de los cuales 1,770 fueron machos y 1,472, hembras. La población de C. bellicosus en la laguna presentó un intervalo de tallas de 40 mm a 190 mm (AC), mostrando dos modas similares para machos y hembras (100 mm y 110 mm, respectivamente). Las relaciones entre el LC-AC para ambos sexos se ajustaron a un modelo de tipo lineal (machos, LC = 0.5265AC-0.0539, R2 = 0.8058, p <0.05; hembras, LC = 0.581AC-0.6335, R2 = 0.7643, p <0.05). La relación AC-PT fue de tipo potencial (machos, PT = 0.561AC3.0751, R2 = 0.7968, p <0.05; hembras, PT = 0.0834AC2.9077, R2 = 0.7589, p <0.05). En hembras se estimó una K= 0.90 años-1 y L∞ = 169 mm, en los machos fue K = 1.20 años-1 y L∞ = 178.5 mm. Conclusiones: Las curvas de crecimiento sugirieron que C. bellicosus alcanzó su longitud máxima de 2.5 a 3 años. La proporción de sexos de 0.81 H : 1 M fue significativa (X2 (0.05, 11) = 19.675, X2 observada = 58.481, p < 0.05

La Colección Ictiológica del Centro Interdisciplinario de Ciencias Marinas del IPN 1993-2011: consolidación y sistematización del acervo

Se documentan las acciones y logros en los últimos 18 años dentro de la Colección Ictiológica (CI) del Centro Interdisciplinario de Ciencias Marinas del Instituto Politécnico Nacional (CICIMAR-IPN), periodo en cual se consolidó su acervo biológico, se llevó a cabo la depuración del inventario, su actualización nomenclatural, se desarrolló su base de datos electrónica y la publicación de la misma en Internet. Se detallan las actividades sobresalientes realizadas en el ámbito académico de la formación de recursos humanos, docencia, investigación, extensión y difusión de los resultados obtenidos. Se discute sobre la función de las colecciones biológicas y las tendencias para la diseminación de la información de las bases de datos

Rock-colonizing plants: abundance of the endemic cactus Mammillaria fraileana related to rock type in the southern Sonoran Desert

Establishment, colonization, and permanence of plants affect biogenic and physical processes leading to development of soil. Rockiness, temperature, and humidity are accepted explanations to the influence and the presence of rock-dwelling plants, but the relationship between mineral and chemical composition of rocks with plant abundance is unknown in some regions. This study documents plant species growing on rocks, their capacity as rock colonizers measured by the Importance Index, and the relationships between the chemical composition of rocks and the abundance of the dominant plant. The community is composed of eight species and is dominated by the small cactus Mammillaria fraileana. Sites with low abundance of this species contain volcanic breccias, high amounts Ca, Fe, Mg, Ti, Al, and Mn as part of moderately weatherable minerals, such as plagioclase and pyroxene. Sites with higher abundance contain rhyodacite, rhyolite, and andesite rocks rich in more weatherable minerals, such as volcanic glass and minerals containing Si, K, and Na. K and Na were present in equal proportions only at the site with more plants. Since Na is toxic for most plants, an experiment was carried out to assess its effect on the survival of M. fraileana seedlings. Decreased survival occurred as the concentration of Na increased. Even in the treatment without Na, survival decreased slightly. In summary, presence and abundance of plants is related to the type of bedrock, their weathering characteristics, and proportion of elements. The interactions among elements, rather than the isolated effect of specific elements, could be the most reliable explanation for local variations in the abundance and dominance of Mammillaria fraileana in rocky habitat in the southern Sonoran Deser

Indirect evidences on the connectivity of coral reefs of the Gulf of Mexico and the mexican caribbean

Coral reef connectivity results from the export and import of species or reproductive product between localities. Possible exchange pathways between the reef ecosystems in the country are not known; such knowledge about coral reef connectivity could contribute to its management and conservation. The connectivity between reefs of the Gulf of Mexico and Mexican Caribbean was evaluated based on patterns of similarity. Information for 48 stony coral species in 19 localities was compiled from different sources. Species richness suggests that the highest coral biodiversity is located around Cozumel on the Caribbean with 33 species. Cluster analysis based on biological similarity between localities shows that the Veracruz Reef System (VRS) is more similar to the reefs of the Mexican Caribbean than those on the Campeche Bank. Correlation (Mantel test) of biological similarity with geographical distance, days of transport by currents and environment variables, was negative and highly significant, corroborating that biological similarity decreases with increasing distances. The hypothesiss that the reefs of the VRS and the Caribbean are more similar because these areas are less affected by hurricanes is proposed. This environmental stability would lead to an accumulation of Caribbean coral species that makes VRS more similar to the Caribbean than to those reefs in the Northern Veracruz or those in the Yucatan shelf

Coral similarity and connectivity of some reefs of the Gulf of Mexico and the mexican caribbean

Coral reef connectivity results from the export and import of species or reproductive product between localities. Possible exchange pathways between the reef ecosystems in the country are not known; such knowledge about coral reef connectivity could contribute to its management and conservation. The connectivity between reefs of the Gulf of Mexico and Mexican Caribbean was evaluated based on patterns of similarity — information for 55 stony coral species in 17 localities. Species richness suggests that the highest coral biodiversity is located in Mahahual on the Caribbean with 37 species. Cluster analysis based on biological similarity between localities shows that the Veracruz Reef System (VRS) is more similar to the reefs of the Mexican Caribbean than those in the Yucatan shelf. Correlation (Mantel test) of biological similarity with geographical distance, days of transport by currents and environment variables, was negative and highly significant, corroborating that biological similarity decreases with increasing distances. The hypothesis that the reefs of the VRS and the Caribbean are more similar because these areas are less affected by hurricanes is proposed. This environmental stability would lead to an accumulation of Caribbean coral species that makes VRS more similar to the Caribbean than to those reefs in the Northern Veracruz or those in the Yucatan shelf