Hidrobiológica (E-Journal)
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New bathymetric record for the fish bighead mora, Laemonema verecundum (Gadiformes: Moridae) in the Gulf of California, Mexico
Get PDFBackground. The presence of Laemonema verecundum (Jordan & Cramer, 1897) had not been previously reported at depths less than 666 m. Goals. The objective of the research was to study the bathymetric distribution of L. verecundum. Methods. In the eastern continental shelf of the Gulf of California, 648 specimens of L. verecundum were collected during two experimental research cruises in September 2004 and February 2005. Results. Specimens were collected at depths between 165 and 483 m, where temperatures ranged between 9.5 and 19.9° C, and average oxygen concentration was 1.7 mg/l. Conclusions. This new record expands the known bathymetric distribution range of this species inhabiting shallow waters in the gulf.Background. The presence of Laemonema verecundum (Jordan & Cramer, 1897) had not been previously reported at depths less than 666 m. Goals. The objective of the research was to study the bathymetric distribution of L. verecundum. Methods. In the eastern continental shelf of the Gulf of California, 648 specimens of L. verecundum were collected during two experimental research cruises in September 2004 and February 2005. Results. Specimens were collected at depths between 165 and 483 m, where temperatures ranged between 9.5 and 19.9° C, and average oxygen concentration was 1.7 mg/l. Conclusions. This new record expands the known bathymetric distribution range of this species inhabiting shallow waters in the gulf
Balance hidrológico y de nutrientes en un humedal costero del Pacífico Sur de México
No full textCoastal lagoons can export or import different amount of materials according to the geographical localization and fluvial and marine regimes associated to them. Talking this in account, water, salinity and nutrient balances (NO2, NO3, NH4 y PO4) were measured in coastal wetland. The volume of fresh water that penetrated into the wetland was different in the two years (1991 and 1992), with a 0.87m3/s average. It was high in September (1.62m3/s) and low in April (0.37m3/s) with 31.4x106 m3/yr. Marinne water was more constant with an average per year of 1.72m3/s, and 28.5x106/yr. This situation favored to oligihaline condition. Nitrates were the most abundant with a high input of 7.5µM in June (16.8 µM) and low input of 1.6 mM in December. The exportation was twice the importation with an average of 14.5 µM. The ammonium and nitrites were second in place in exportation. The fluvial input of orthophosphates to wetland was less than to the sea exportation. The lower amount caused by a diminishing river flow. The export of nutrients from the wetland was greater than the import, with 86.5 ton/yr vs 48.2 ton/yr, respectively. The former meaning, a great marine nutrient enrichment by consequence of the mangrovve area.Las lagunas costeras exportan o importan materiales, según donde estén ubicadas y el régimen fluvial y marino asociados a ellas. Con base en este concepto se midió en un humedal costero del SO de México el balance de agua dulce, salobre y nutrientes (NO2, NO3, NH4 y PO4) durante dos años. El volumen de agua dulce que penetró al humedal fue mayor en 1991 que en 1992, con un promedio de 0.87m3/s, con los máximos en septiembre (1.62m3/s) y mínimos en abril (0.37m3/s). La cantidad introducida de agua marina fue más constante durante el año con un promedio de 1.77m3/s. El volumen de agua dulce fue mayor que la marina con 31.4x106m3 vs 28.5x106m3 . Esta situación favoreció a condiciones oligohalinas durante gran parte del año en todo el humedal. Apesar de la variación en el contenido de nutrientes, los nitratos (NO3) fueron los mas abundantes con un aporte vñia fluvial promedio anual de 7.5µM; la exportación duplicó a las entradas con un promedio de 14.5 µM, le siguieron en amonio (NH4) y nitritos (NO2). La entrada fluvial de ortofosfatos (PO4) al humedal, tambiéb fue inferior que la exportación al mar. Durante las lluvias el humedal recibió 33.7 ton/nutrientes contra 14.45 en el estiaje debido a la disminución del agua del río. La exportación de nutrientes por el humedal fue superior a las entradas fluviales con 86.5 ton/año vs. 48.2 ton/año; lo anterior señala el gran enriquecimiento de nutrientes del medio marino por parte del área del manglar
Patrones espaciales de la riqueza de peces en lagunas costeras del sur de Quintana Roo, México
No full textThirty nine fish species are recorded in eight lagoons on the southern coast of Quintana Roo. "Cichlasoma" urophthalmus, Gambusia yucatana, Poecilia orri and Eugerres plumieri were the most widely distributed species. Cluster analysis on the lagoons, based on presence-absence of the fishes, generated a dendrogram where two lagoon complexes are identifiable, divided by the access road to Mahahuak. The northern complex (Uvero, Placer, San Humberto and San Antonio) is characterized by the presence of Astyanax aunus, "C." synspilum and Thorichthys meeki. The southern complex (Río Huach, Xcalak, Cementerio and La Aguada) is characterized by Cyprinodon artifrons, Floridichthys polyommus, Eucinostomus argenteus, E. jonessi and Gerres cinereus. Both beta and gamma diversity shown an increase from north to south, a fact explained mainly by the larger number of peripheral species migrating from the adjacent reef through permanent mangrove channels to Caribbean Sea in lagoons Río Huach and Xcalak, in the southern complex, as well as the absence of primary species in these lagoons.Se registran 39 especies de peces en ocho lagunas de la costa sur de Quintana Roo. "Cichlasoma" urophthalmus, Gambusia yucatana, Poecilia orri y Eugerres plumieri son las especies de más amplia distribución en la zona. El análisis de clasificación jerárquica por conglomerados sobre las lagunas, basado en la composición íctica (presencia/ausencia), generó un dendrograma en donde se identifican dos complejos lagunares divididos por la carretera de acceso a Mahuahual. El complejo norte (Uvero, Placer, San Humberto y San Antonio) se caracteriza por la presencia de Astyanax aeneus, "C." synspilum y Thorichthys meeki. El complejo sur (Río Huach, Xcalak, Cementerio y La Aguada) se caracteriza por Cyprinodon artifrons, Floridichthys polyommus, Eucinostomus argenteus, E. jonesi y Gerres cinereus. La tasa de recambio de especies entre las lagunas, igual que la tendencia en la diversidad gamma en la región, muestran incremento de norte a sur, lo cual responde principalmente al mayor número de especies periféricas que migran del arrecife adyacente a través de los canales de comunicación permanente con el mar Carie que presentan Río Huach y Xcalak, en el sur, así como a la ausencia de especies primarias en dichas lagunas
Efecto de la temperatura sobre la proporción sexual de Poecilia reticulata Peters, 1859 (Pisces: Poeciliidae)
No full textWas evaluate th effect of the water temperature on the sex ratio in two populations of Poecilia reticulata, a where it is common practice the inbreeding (native) and another result of a crosses of a imported variety mattered with a local (mestizo). The factorial experiment design (2x3) considered both, the populations and the water temperature (21, 25 and 31 ± 1ºC). Fifteen juveniles of 2 ± 1 days of age were randomly assigned to each trial with three repetitions, each treatment had 45 fishes (N=270 caseS). During the experimental period survival fluctuated between 91 and 100%. The results indicated that both, temperature and variety of fish species influenced masculinization. The fish mae of mestizo population reaches 34.9% at 25 ± 1ºC and 63.6% at 31 ± 1ºC, while in the native population males were only 3.5 and 2.3% at 25 and 31 ± 1ºC, respectively. At the lower temperature of 21 ± 1ºC no variation in the sex ratio was observed in the later population and only 4.8% in the former. I was concluded that the highest temperature alters the proportion of sexes, being 31 ± 1ºC the one that induced the highest proportion of males in the mestizo population of P. reticulata.Se evaluó el efecto de la temperatura del agua sobre la proporción de sexos en dos poblaciones de Poecilia reticulata, una donde es común la endogamia (nativa) y otra resultado del cruzamiento entre una variedad importada y una local (Mestiza). El diseño experimental fue factorial (2x3), se consideraron las poblaciones y la temperatura (21, 25 y 31 ± 1ºC). Los juveniles de cada población de una edad de 2 ± 1 días fueron asignados aleatoriamente a una densidad de 15 peces por acuario y se realizó por triplicado, es decir 45 peces por tratamiento (N=270 casos). Durante el periodo experimental la sobrevivencia fluctuó entre el 91 y 100%. Los resultados indicaron que la temperatura y el tipo de población influyeron en la masculinización; en la población nativa los machos alcanzan el 34.9% a 25 ± 1ºC y 63.6% a 31 ± 1ºC, mientras que en la población nativa los machos son el 3.5 y 2.3% a 25 y 31 ± 1ºC, respectivamente. En la temperatura más baja, de 21 ± 1ºC, no se observó variación en la proporción sexual en esta última población y en la primera sólo el 4.8% fueron machos. Se concluye que las temperaturas altas influyen en la porporción sexual, siendo la de 31 ± 1ºC la que induce la mayor proporción de machos en la población nativa de P. reticulata
Composición estacional del fitoplancton de dos lagunas costeras del Pacífico tropical
Get PDFThis paper presents the seasonal composition and distribution of the microphytoplankton comunity collected during the period 1997-2002 in two coastal lagoons, Chantuto-Panzacola (CH-P) and Carretas-Pereyra (C-P), located in the state of Chiapas, Mexico. A total of 199 and 125 taxa were identified in CH-P and C-P respectively; in both systems more than 60% of the composition was represented by diatoms, followed in order of importance by dinoflagellates, chlorophytes, cyanophytes, euglenophytes, and finally by silicoflagellates. The results of a Principal Components Analysis (PCA) of stations, based on the presence/absence of species, generated the discrimination of two analogous zones for each system. These zones correspond with the environmental gradient generated by physical and chemical variables like salinity and nutrients which explain more than 70% of the variance and allow the differentiation of two groups of communities: during dry season there was a dominance of alocthonous (neritic) phytoplankton like diatoms and dinoflagellates, distributed mainly in the zone of greater tidal influence; in the rainy season the community was integrated by freshwater groups (chlorophytes, cianophytes, and euglenophytes) as well as of diatoms with brackish affinities (Surirella spp.).El presente trabajo tuvo como objetivo determinar la distribución espacial y temporal del microfitoplancton, colectado durante el periodo de 1997 a 2002 en las lagunas costeras Chantuto-Panzacola (CH-P) y Carretas-Pereyra (C-P), Chiapas, en las dos épocas climáticas características de la región (secas y lluvias), así como las variables que determinan esta distribución. Se identificaron un total de 199 taxa en el sistema CH-P y 125 en C-P, en ambos sistemas más del 60% estuvo representado por las diatomeas, seguidas en orden de importancia por los dinoflagelados, clorofitas, cianofitas, euglenofitas y por último de los silicoflagelados. El análisis de similitud entre estaciones, basado en la presencia/ausencia de las especies, dio como resultado la discriminación de dos zonas análogas para cada sistema relacionadas con el gradiente ambiental generado por las variables físico-químicas de salinidad y nutrientes y determinado mediante un Análisis de Componentes Principales (ACP); estas variables explican más del 70% de la varianza y permiten la diferenciación de dos grupos de comunidades: durante la época de secas se observó la dominancia de grupos fitoplanctónicos alóctonos como diatomeas y dinoflagelados, distribuidos principalmente en el zona de mayor influencia mareal; en la temporada de lluvias la comunidad estuvo integrada por grupos dulceacuícolas (clorofitas, cianofitas y euglenofitas), así como de diatomeas con afinidades salobres (Surirella spp.)
O gênero Dictyopteris J.V. Lamour. (Dictyotaceae - Phaeophyta) no estado da Bahia, Brasil
Get PDFEste estudo faz parte de um levantamento florístico de algas marinhas bentônicas do estado da Bahia, desenvolvido pela Universidade Federal da Bahia. Através da análise de caracteres morfo-anatômicos foram reconhecidos e ilustrados seis espécies: Dictyopteris delicatula J.V. Lamour., D. jamaicensis W.R. Taylor, D. jolyana E.C. Oliveira & R.P. Furtado, D. justii J.V. Lamour., D. plagiogramma (Mont.) Vickers e D. polypodioides (DC. in Lam. & DC.) J.V. Lamour. Referência da descrição original, basiônimo, descrição morfológica, distribuição geográfica ao longo do litoral brasileiro e comentários taxonômicos são apresentados. Chave dicotômica para identificação das espécies também é incluída. D. Jamaicensis constitui-se em primeira referência para o litoral baiano.Este estudo faz parte de um levantamento florístico de algas marinhas bentônicas do estado da Bahia, desenvolvido pela Universidade Federal da Bahia. Através da análise de caracteres morfo-anatômicos foram reconhecidos e ilustrados seis espécies: Dictyopteris delicatula J.V. Lamour., D. jamaicensis W.R. Taylor, D. jolyana E.C. Oliveira & R.P. Furtado, D. justii J.V. Lamour., D. plagiogramma (Mont.) Vickers e D. polypodioides (DC. in Lam. & DC.) J.V. Lamour. Referência da descrição original, basiônimo, descrição morfológica, distribuição geográfica ao longo do litoral brasileiro e comentários taxonômicos são apresentados. Chave dicotômica para identificação das espécies também é incluída. D. Jamaicensis constitui-se em primeira referência para o litoral baiano
Caracterización diatomológica en tres cuerpos de agua de los humedales de Jilotepec-Ixtlahuaca, Estado de México
Get PDFThe taxonomic and environmental characteristics of the diatom flora found in three bodies of water in the wetlands of Jilotepec-Ixtlahuaca, Estado de Mexico are described. Six samplings were made (January-October, 2001). Benthic and planktonic diatoms growth were collected.The samples were analyzed with a Light Microscope (LM) and a Scanning Electron Microscope (SEM). 45 species and 3 infraspecific taxa belonging to 32 genera were identified. Aulacoseira granulata, Cymbella affinis, Gomphonema acuminatum, G. angustatum, Pinnularia microstauron, Synedra ulna y Stephanodiscus niagarae were the dominat species. Craticula halophila, Cymatopleura solea, and Neidium iridis were rare species. Epithemia turgida, Eunotia curvata and Rhopalodia sp. were species specific to the permanent pond. Achnanthes pinnata, Cyclostephanos dubius, Eunotia faba and Planothidium ellipticum are new records for theTrans Mexican Volcanic Belt. We found a living population of S. niagarae from wetlands, suggesting that this species had once a much wider distribution towards the southern region of North America. 89% of the species were limnophilous with an indifferent and rheophilous tendency. 67% of the taxa were associated to the diversity of substrates and did not exhibit marked seasonality. Species richness was higher during dry season. Craticula halophila, Encyonema caespitosum, Frustulia vulgaris y Sellaphora pupula were found during the rainy season. All of the species were found to be meso-eurytherms with temperate affinity. pH was slightly basic (7.8), 65% of the species were alkaliphilous. Eunotia faba, acidophilous-circumneutral, Eunotia curvata and Surirella tenera circumneutral-indifferent. Stephanodiscus niagarae in association with Aulacoseira granulata, Fragilaria capucina and F. crotonensis showed a tendency to eutrophic condition. All of the species were characterized as being from freshwater and oligohalobous. Results from environmental analysis show that the water from study area has a low mineral contentSe representa la caracterización taxonómica y ambiental de las diatomeas de tres cuerpos de agua de los humedales de Jilotepec-Ixtlahuaca, Estado de México, a partir de seis muestreos (enero-octubre de 2001). Se colectaron crecimientos algales bentónicos y planctónicos. Los taxa se estudiaron con microscopio de luz y electrónico de barrido. Se identificaron 45 especies y 3 variedades de diatomeas distribuidas en 32 géneros. Aulacoseira granulata, Cymbella affinis, Gomphonema acuminatum, G. angustatum, Pinnularia microstauron, Synedra ulna y Stephanodiscus niagarae fueron especies dominantes. Por el contrario Craticula halophila, Cymatopleura solea y Neidium iridis fueron raras. Epithemia turgida, Eunotia curvata y Rhopalodia sp. fueron particulares del charco permanente. Achnanthes pinnata, Cyclostephanos dubius, Eunotia faba y Planothidium ellipticum son nuevos registros para la FVTM. La presencia de S. niagarae amplia su distribución como especie viviente hacia el sur de Norte América. El 89% de las especies fueron limnófilas, con tendencia a indiferentes y a reófilas. El 67% de los taxa estuvieron asociados con la diversidad de sustratos y no manifestaron marcada estacionalidad. La riqueza de especies fue mayor durante la época de secas. Craticula halophila, Encyonema caespitosum, Frustulia vulgaris y Sellaphora pupula se encontraron en época de lluvias. Todas las especies fueron meso-euritermales con afinidad templada. El pH fue ligeramente básico (7.8), el 65% de las especies fueron alcalífilas. Eunotia faba, acidófila-circumneutral, E. curvata y Surirella tenera circumneutral-indiferentes. Stephanodiscus niagarae en asociación con Aulacoseira granulata, Fragilaria capucina y F. crotonensis, indican una tendencia a condiciones eutróficas. Todas las especies son características de agua dulce y oligohalobias. Los resultados de las variables ambientales medidas indicaron que el agua del área de estudio es poco mineralizada
Fenología de macroalgas marinas
Get PDFA loose usage of the term phenology in marine macroalgae studies has caused that other type of events have been recorded as phenological. In order to develop criteria as uniform as possible that allow conducting comparable studies among phycologists, the following definition of phenology is proposed to be adopted: the study of the timing of recurring biological events and the causes of their timing with regard to abiotic and biotic factors. The use of this definition is appropriate in phenological studies of other organisms and encompasses a set of delimitations, based on an analysis of vascular plant phenology. Approaches to gather and analyze phenological variables are suggested. The importance of undertaking long term and large spatial scale studies is highlighted. The relevance of including all reproductive phases of macroalgae life histories is also emphasized in carrying out phenological studies.El uso laxo del término fenología en estudios de macroalgas marinas ha propiciado que se registren como fenológicos a eventos que no son de ese tipo. Para uniformizar criterios que generen estudios ficológicos comparables entre investigadores, se sugiere adoptar la siguiente definición de fenología: estudio de la temporalidad de los eventos biológicos recurrentes y las causas de su empate temporal con respecto a factores abióticos y bióticos. Esta definición es adecuada para aplicarse en estudios fenológicos de otros organismos y contiene una serie de acotamientos, de acuerdo a un análisis de la fenología en plantas vasculares. Se sugieren formas de medición y análisis de eventos fenológicos de macroalgas. Se resalta la importancia de efectuar estudios de largo plazo y a escalas espaciales amplias. De manera similar, se destaca la importancia de considerar las diversas fases del ciclo de vida de las macroalgas en estudios fenológicos
Wild-caught Hybrids Between Sailfin and Shortfin Mollies (Poeciliidae, Poecilia): Morphological and Molecular Verification
Get PDFThis study documents four wild-caught, interspecific hybrids between sailfin mollies (Poecilia velifera or P. petenensis) and shortfin mollies (P. mexicana or P. orri) from the Yucatán peninsula and Isthmus of Tehuantepec regions of México. In canonical discriminant analysis of morphological data all four putative hybrid males were intermediate in shape between shortfin and sailfin molly species, falling well outside 95% confidence ellipses for those putative parental species. For two of the four hybrid individuals, we used allele size differences at the nuclear Xsrc gene between sailfin and shortfin species to determine that one was a first (F1) or early generation (F2, BC1) hybrid and the other was a later generation (>F1) hybrid. Sequences of the mtDNA control region (483 bp) and Xsrc nuclear gene (636 bp) indicated that the female parent of the early generation hybrid individual was P. mexicana and the male parent was P. velifera. Thus, while rare in the wild, interspecific hybridization and introgression between sailfin and shortfin mollies does occasionally occur despite the existence of behavioral pre-mating isolating mechanisms
Seasonal pattern of the fish assemblage of El Conchalito mangrove swamp, La Paz Bay, Baja California Sur, Mexico
Get PDFThe 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