[Spatial and temporal mangrove litter production in Barra de Navidad lagoon, Jalisco, México]. / Producción especial y temporal de hojarasca del manglar en la laguna Barra de Navidad, Jalisco, México.

Barra de Navidad lagoon is a coastal wetland of international importance (Ramsar site) and it is included among the 81 Mexican mangrove priority sites. One of the most valued characteristics of this lagoon is the presence of mangrove forest in a good conservation state. The goal of our research was the measurement of mangrove litter production and environmental factors influencing its dynamics. The mangrove area was divided into seven zones and litterfall was monthly sampled from November 2011 to October 2012 using 0.25 m(2) square collectors made with mosquito mesh (1 mm) and positioned at 1.3 m above the ground. Abiotic variables of the interstitial water were measured simultaneously at each zone in permanent plots using a multi-parameter probe, YSI-556-M. Total mean value of litterfall production, weighted by zone surface, was 19.12 ± 1.23 gPS/m(2).mo (2.29 t/ha.year). This low productivity is a consequence of the region's dry climate and low tide range. The species Avicennia germinans and Laguncularia racemosa produced more than 80 % of total litterfall, while Rhizophora mangle contributed only 16 % and Conocarpus erectus < 4 %. A significant correlation between litterfall production and abiotic variables was found (e.g. salinity and interstitial water depth). We concluded that there are significant spatial variations in soil abiotic variables which are correlated with differences in mangrove species composition, and produce, together with the life cycles stages of those species, significant variations in the quantity and composition of litterfall. Future research will be focused on quantifying spatial variations in forest structure and their relationship with litterfall production.

Inter-habitat variation in density and size composition of reef fishes from the Cuban Northwestern shelf.

Movement and exchange of individuals among habitats is critical for the dynamics and success of reef fish populations. Size segregation among habitats could be taken as evidence for habitat connectivity, and this would be a first step to formulate hypotheses about ontogenetic inter-habitat migrations. The primary goal of our research was to find evidence of inter-habitat differences in size distributions and density of reef fish species that can be classified a priori as habitat-shifters in an extensive (-600km2) Caribbean shelf area in NW Cuba. We sampled the fish assemblage of selected species using visual census (stationary and transect methods) in 20 stations (sites) located in mangrove roots, patch reefs, inner zone of the crest and fore reef (12-16m depth). In each site, we performed ten censuses for every habitat type in June and September 2009. A total of 11 507 individuals of 34 species were counted in a total of 400 censuses. We found significant differences in densities and size compositions among reef and mangrove habitats, supporting the species-specific use of coastal habitats. Adults were found in all habitats. Reef habitats, mainly patch reefs, seem to be most important for juvenile fish of most species. Mangroves were especially important for two species of snappers (Lutjanus apodus and L. griseus), providing habitat for juveniles. These species also displayed well defined gradients in length composition across the shelf.

[Species and size composition of fishes in Barra de Navidad lagoon, Mexican central Pacific]. / Composición per especies y tallas de los peces en la laguna Barra de Navidad, Pacífico central mexicano.

Coastal lagoons are considered important nursery areas for many coastal fishes. Barra de Navidad coastal lagoon (3.76km2) is important for local economy as it supports tourism development and artisanal fisheries. However, the role of this lagoon in the dynamics of coastal fish populations is scarcely known. Thus, the objectives of this research were: to characterize the water of the lagoon and related weather conditions, to develop a systematic list of the ichthyofauna, and to estimate the proportion of juveniles in the total number of individuals captured of most abundant species. Water and fish samples were collected between March 2011 and February 2012. Physical and chemical variables were measured in rainy and dry seasons. Several fishing gears were used including a cast net, beach purse seine and gillnets of four different mesh sizes. Our results showed that the lagoon is most of the time euhaline (salinity 30-40ups), although it can be mixopolyhaline (salinity 18-30ups) during short periods. Chlorophyll and nutrients concentrations suggested eutrophication in the lagoon. Mean water temperature changed seasonally from 24.9 degrees C (April, high tide) to 31.4 degrees C (October, low tide). Considering ichthyofauna species, a total of 36 448 individuals of 92 species were collected, 31 of them adding up to 95% of the total of individuals caught. Dominant species were Anchoa spp. (44.6%), Diapterus peruvianus (10.5%), Eucinostomus currani (8.1%), Cetengraulis mysticetus (7.8%), Mugil curema (5.2%) and Opisthonema libertate (4.5%). The lagoon is an important juvenile habitat for 22 of the 31 most abundant species. These included several species of commercial importance such as snappers (Lutjanus argentiventris, L. colorado and L. novemfasciatus), snook (Centropomus nigrescens) and white mullet (Mugil curema). Other four species seem to use the lagoon mainly as adults. This paper is the first contribution on the composition of estuarine ichthyofauna in Jalisco State, and it also constitutes the more complete reference on the detailed size composition of a set of dominant species in a coastal lagoon in the central Mexican Pacific.

Nesting ecology of Chelonia mydas (Testudines: Cheloniidae) on the Guanahacabibes Peninsula, Cuba.

The nesting colony of green sea turtles (Chelonia mydas) at Guanahacabibes Peninsula Biosphere Reserve and National Park is one of the largest in the Cuban archipelago; however, little information about its nesting ecology is available. Temporal and spatial variation in nesting and reproductive success as well as morphometric characteristics of gravid females were used to ecologically characterize this colony. Nine beaches of the Southernmost coast of Guanahacabibes Peninsula were monitored for 14 years (1998-2012) to determine green turtle nesting activity, from May to September (peak nesting season in this area). Beach dimensions were measured to determine nest density using the length and the area. Afterward the beaches were divided in two categories, index and secondary. Females were measured and tagged to compare new tagged females (823) with returning tagged females (140). Remigration interval was also determined. Temporal variation was identified as the annual number of nesting emergences and oviposits per female, with apparent peaks in reproductive activity on a biennial cycle in the first six years followed by periods of annual increase in nest number (2003-2008) and periods of decreasing number of nests (2010-2012). We also found intra-seasonal variation with the highest nesting activity in July, particularly in the second half of the month. The peak emergence time was 22:00-02:00 hr. In terms of spatial variation, smaller beaches had the highest nest density and nesting was more frequent 6-9m from the high tide line, where hatchling production was maximized although hatchling success was high on average, above 80%. Morphometric analysis of females was made and newly tagged turtles were smaller on average than remigrants. Our results are only a first attempt at characterizing Guanahacabibes' populations but have great value for establishing conservation priorities within the context of national management plans, and for efficient monitoring and protection of nesting beaches.

Increased mercury and body size and changes in trophic structure of Gambusia puncticulata (Poeciliidae) along the Almendares River, Cuba.

The Almendares River is the largest river draining the area around Havana City, Cuba. The watershed is heavily populated and industrialized, which has had a significant impact on the flow and water quality of the river. The main goal of this study was to analyze the spatial variability in dietary habits, nutrient flow (using stable isotope ratios δ(15)N and δ(13)C), and mercury (Hg) levels along the Almendares River upstream and downstream of point-source discharges using localized fish Gambusia puncticulata. Stomach contents of G. puncticulata were similar among these sites. However, mean δ(15)N values ranged from 6 to 18 ‰ across sites and were lower in fish from downstream than upstream sites, suggesting localized influences of nutrient inputs along the river. δ(13)C values were between -22 and -25 ‰, except at a mid-basin site (-26 to -27‰), indicating that fish relied on similar carbon sources at most sites. Total mercury concentrations ranged from 0.04 to 0.49 µg/g wet weight whole body and were unrelated to the among-site differences in δ(15)N, but Hg exceeded the threshold considered to be protective of fish health (0.2 µg/g ww whole body) in the majority of fish from all sites but one. Results of this study indicate that although the dietary habits of this species do not vary across sites, tissue differences in δ(15)N, δ(13)C and Hg show little movement of this species among sites. Localized effects of human activities on nutrients and metals may be affecting the health of this species and posing a risk to other consumers in the ecosystem.

[Reproductive biology of Anisotremus interruptus (Perciformes: Haemulidae) in the Mexican Central Pacific]. / Biología reproductiva de Anisotremus interruptus (perciformes: Haemulidae) en el Pacífico central mexicano.

Anisotremus interruptus is a widely distributed and commercially important species in the Eastern Pacific. A multi-year research on the reproduction of this species was carried out in coastal waters of Jalisco, Mexico. For this purpose, monthly samples were gathered with gillnets of different mesh sizes from 1998-2008. A total of 1090 individuals were collected with a total length range between 15.6-61.0cm. Significant differences from expected 1:1 ratio were found for sex ratios in the total sample and for each size class, but not when comparisons among months and years were done. Temporal variations of the gonadosomatic index and proportions of maturation stages suggest that the main reproductive period is from February to May, although some less intensive spawning events were observed in other months. Seven stages of oocytes development were identified. Oocytes in different stages of development were identified in ovaries classified as mature, suggesting an asynchronic type of gonad development. Mean maturation length (L50) was 31.0 for females and 29.7cm for males. The internal organization of testes is of lobular type.

[Reproductive biology of the golden snapper Lutjanus inermis (Perciformes: Lutjanidae) in the central Mexican Pacific]. / Biología reproductiva del pargo Lutjanus inermis (Perciformes: Lutjanidae), en el Pacífico central mexicano.

Reproductive aspects and information on the effect of fishery activities over this species stock are scarce, despite the imperative need of effective protection and resource management programs. To support the possible establishment of closed seasons and catch levels for the area, our study aimed to evaluate the spawning season of the Golden snapper (Lutjanus inermis). For this, fish caught by artisanal fisheries in the Navidad, Tenacatita and Chamela bays (Jalisco, Mexico) were sampled monthly from 1999-2008, and analyzed sex ratios, spawning season and size at first maturity. A total of 311 (53.1%) females and 275 (46.9%) males were caught, and the observed sex ratio was 1:0.88. The total length range was 14.4-37.0cm and total weight range from 48-575g. The length at first maturity was 23.9cm TL for females and 23.6cm TL for males. The gonadosomatic index showed two principal reproductive periods in the year (February-April and September-November), when the largest number of mature gonads were observed. Ovaries were of asynchronic development type and seven oocyte development stages were identified. Testicles showed lobular development and spermatozoa were observed in the center of the cysts and in the collecting ducts. It is important to mention that our results support the current suitable exploitation of this species in the area.

[Reproduction of the spiny puffer, Diodon holocanthus (Pisces: Diodontidae) in the continental shelf of Mexican Central Pacific]. / Reproducción del pez erizo, Diodon holocanthus (Pisces: Diodontidae) en la plataforma continental del Pacífico Central Mexicano.

Diodon holocanthus is an important economic and ecological species of the demersal fish community, caught as bycatch from local shrimp fishery. The reproductive biology of this long-spine porcupinefish has not yet been described, and reproductive season, the sex ratio, length distribution, length at first gonad maturity, and the gonad macro and microscopic features are described. A total of 400 organisms, ranging from 5.0 to 40.3 cm (average 18.4 cm) total length, were caught from the continental shelf of the Central Mexican Pacific, from December 1995 and December 1998. Sex ratio was 1:0.86 females to males (n = 253). The length at which 50% of the individuals showed maturing gonads was 19.7 cm for females and 20.1 cm for males. Length of the smallest organism with ripe gonads was 12.2 cm for females and 13 cm for males. Four gonadal maturation stages were found in both sexes, and five oocyte development phases were identified. The oocyte development pattern is of asynchronous type, which means the species can reproduce several times a year. Testicle development is lobular type, as in most teleost fishes. Monthly mean values of the gonad-somatic index suggest the reproduction activity peaks in June, and September-December.

Influence of Diadema antillarum populations (Echinodermata: Diadematidae) on algal community structure in Jardines de la Reina, Cuba.

The 1983-1984 mass mortality of Diadema antillarum produced severe damages on Caribbean reefs contributing to substantial changes in community structure that still persist. Despite the importance of Diadema grazing in structuring coral reefs, available information on current abundances and algal-urchin interactions in Cuba is scarce. We analyzed spatial variations in Diadema abundance and its influence on algal community structure in 22 reef sites in Jardines de la Reina, in June/2004 and April/2005. Urchins were counted in five 30 x 2m transects per site, and algal coverage was estimated in randomly located 0.25m side quadrats (15 per site). Abundances of Diadema were higher at reef crests (0.013-1.553 ind/m2), while reef slope populations showed values up to three orders of magnitude lower and were overgrown by macroalgae (up to 87%, local values). Algal community structure at reef slopes were dominated by macroalgae, especially Dictyota, Lobophora and Halimeda while the most abundant macroalgae at reef crests were Halimeda and Amphiroa. Urchin densities were negatively and positively correlated with mean coverage of macroalgae and crustose coralline algae, respectively, when analyzing data pooled across all sites, but not with data from separate habitats (specially reef crest), suggesting, along with historical fish biomass, that shallow reef community structure is being shaped by the synergistic action of other factors (e.g. fish grazing) rather than the influence of Diadema alone. However, we observed clear signs of Diadema grazing at reef crests and decreased macroalgal cover according to 2001 data, what suggest that grazing intensity at this habitat increased at the same time that Diadema recruitment began to be noticeable. Furthermore, the excessive abundance of macroalgae at reef slopes and the scarcity of crustose coralline algae seems to be due by the almost complete absence of D. antillarum at mid depth reefs, where local densities of this urchin were predominantly low.

High spatial variability of coral, sponges and gorgonian assemblages in a well preserved reef.

The main goal of this research was to obtain baseline field data of the composition of sponges, corals, and gorgonian assemblages that can be used as a reference for future analyses of anthropogenic impact. We tested the hypothesis that relatively homogeneous and well preserved reef units can present notable natural variability in the composition of their communities which are unassociated with changes in land proximity or a human impact gradient. Research was carried out in July 2006 at Los Colorados reef, located in the northwestern region of Pinar del Río Province, Cuba at 12 sampling stations. The biotopes selected were crest, terrace edge and spur and grove. Ecological indicators were diversity of corals, species composition, density of corals, hydrocorals, gorgonians and sponges, and density of selected coral species. A total of 2659 colonies of scleractineans corals representing 36 species were counted. The most abundant species in the crest biotope were Millepora alcicornis, Acropora palmata and Porites astreoides; in the terrace edge and spur and grove, the most abundant species were Siderastrea siderea, Stephanocoenia intersepta, Porites astreoides, Agaricia agaricites and Montastraea cavernosa. We found differences among sites for several indicators (e.g. density of corals, sponges and gorgonians and for selected species), but they could not be associated to any gradient of land influence or human impact. Therefore, sites inside a relatively homogeneous reef unit can present notable natural differences in the composition of their communities.

[Analysis of diet composition and overlap in four species of the genus Diplectrum (Perciformes: Serranidae) in the Mexican Central Pacific]. / Composición y superposición de dietas en cuatro especies de Diplectrum (Perciformes: Serranidae) en el Pacífico central mexicano.

Analysis of diet composition and overlap in four species of the genus Diplectrum (Perciformes: Serranidae) in the Mexican Central Pacific. The information of trophic interactions among species is essential to understand ecosystem function. To assess this in four Diplectrum species, we analyzed the stomach contents of 397 individuals caught using shrimp trawling nets off the coasts of Jalisco and Colima, Mexico. Main food component of D. eumelum were fish of the Order Pleuronectiformes, followed by shrimps (Metapenaeopsis spp). D. euryplectrum feeds mainly on crustaceans, with stomatopods (Squilla mantoidea) as main food items followed by shrimps and brachyurans. Fish and polychaetes had a low representation in the diet of this species. D. labarum feeds mainly on crustaceans, mollusks and fish. The stomatopod Eurysquilla veleronis contributed to with a high diet percentage by weight, followed by shrimps (mostly Solenoceraflorae) and brachyurans, as well as the squid Lolliguncula diomedae. Fishes (Ophidion spp.) were also an important component of the diet of this species. The most common preys of D. rostrum were crustaceans, mollusks, polychaetes and fish. The squid Lolliguncula diomedae and fishes of genus Ophidion were also well represented in the diet. Diet breadth index yielded significant differences between species. The number of diet items varied from 16 in D. euryplectrum to 6 in D. eumelum. The average value of overlap (0.247) was not significantly different (p = 0.118) from the expected one for a null model (0.174). The observed variance of the overlap index (0.071) was significantly higher (V = 0.025, p = 0.0004) than the value expected for a null model.

Natural and human-induced variability in the composition of fish assemblages in the Northwestern Cuban shelf.

The main goal of the study was to obtain field data to build a baseline of fish assemblage composition that can be used comparatively for future analyses of the impact of human actions in the region. A basic network of 68 sampling stations was defined for the entire region (4,050 km2). Fish assemblage species and size composition was estimated using visual census methods at three different spatial scales: a) entire region, b) inside the main reef area and c) along a human impact coastal gradient. Multivariate numerical analyses revealed habitat type as the main factor inducing spatial variability of fish community composition, while the level of human impact appears to play the main role in fish assemblage composition changes along the coast. A trend of decreasing fish size toward the east supports the theory of more severe human impact due to overfishing and higher urban pollution in that direction. This is the first detailed study along the northwest coast of Cuba that focuses on fish community structure and the natural and human-induced variations at different spatial scales for the entire NW shelf. This research also provides input for a more comprehensive understanding of coastal marine fish communities' status in the Gulf of Mexico basin.

[Reproductive and morphological indicators of the fish Gambusia puncticulata (Poeciliidae) in very polluted sections of Almendares River, Cuba]. / Indicadores morfológicos y reproductivos del pez Gambusia puncticulata (Poeciliidae) en sitios muy contaminados del río Almendares, Cuba.

The Almendares River watershed covers a large portion of Havana city. Human activities have negative impacts over it. We studied the alteration of biological processes in fish from polluted sites. Stressor-based cumulative effects assessment was applied at individual level in Gambusia puncticulata (Poey, 1854). Three sites of Almendares River were sampled monthly from July 2006 to June 2007. Length and weight of females, and condition factor for both sexes, were higher in the impacted sites. An increase of food supply due to eutrophication can explain why fishes are heavier and longer at polluted sites. Gonadosomatic, specific fecundity index and embryo numbers were significantly higher on the reference site. The Hepatosomatic index was higher in females from the most contaminated sites. Differences in delta(13)C and delta(15)N among contaminated and reference sites suggest that the food source is not the same.

[Trophie webs of reef fishes at Cuba's NW area. II. Functional groups]. / Tramas tróficas de peces de arrecifes en la región noroccidental de Cuba. II. Grupos funcionales.

A conceptual model of the food webs, mainly with fish, was built in a rocky shore of Havana City with data covering from October 2004 to February 2006. The stomach contents of the most abundant fish was complemented with the literature. We used the Relative Importance Index method to describe diets of carnivorous and omnivorous fish; and a modification of the Relative Abundance method for sponge eaters and herbivorous fish. Agglomerative numeric classification techniques were used to determine the diet's similarity. The matrix was made using Bray-Curtis dissimilarity index. Ten functional trophic groups were formed on the basis of diet similarity. The cascade effect is evidenced in this area by the big top predator shortage and the dominance of a few low trophic level species. The regulator role of top predators is low because of over-fishing: the trophic web of this area is highly altered.

Fishes as indicators of untreated sewage contamination in a Mexican coastal lagoon.

Lagoons are important nursery habitats for fishes but are often sites of intense human activity including wastewater discharges. The goal of this research was to compare stable nitrogen (δ15N) and carbon (δ13C) isotopes, total mercury (THg) and other metal levels in four selected fish species among sites with different levels of untreated sewage discharge inside Barra de Navidad coastal lagoon in the Mexican Pacific. Three species from sites heavily impacted by sewage showed higher δ15N and δ13C compared to those from non-impacted sites. In addition, the highest concentrations of THg were present in fish of two species (Sciades guatemalensis and Diapterus brevirostris) collected at the two most impacted sites, and exceeded the 0.2µg/g ww threshold believed to be protective of adult and juvenile fish. No individuals of Achirus mazatlanus and Mugil curema exceeded this threshold, and liver somatic index and condition did not distinguish high from low impacted sites for all species. In general, the metal levels differed among species but not sites, and were lower than what has been measured in fishes elsewhere. The study also provides the first information on several fish species for coastal areas of Mexico, suggests that THg and isotopes can distinguish sewage-impacted sites, and can serve as a baseline for future studies.

Influencia del sustrato en la composición de la ictiofauna en zonas someras de la laguna costera Barra de Navidad, México / Substrate influence on ichthyofaunal composition in shallow areas of Barra de Navidad coastal lagoon, Mexico

Introducción: Las lagunas costeras son hábitats importantes para los peces costeros y juegan un rol esencial como áreas de crianza para muchas especies. Mientras que los efectos de la salinidad y la temperatura sobre la abundancia de los peces han sido bien documentados, las investigaciones sobre la influencia de las características del sustrato son más escasas. Objetivo: Investigar la correlación de la salinidad, la temperatura y las características del sedimento con las variaciones espaciales y temporales de la composición de la ictiofauna en las zonas someras de la laguna costera Barra de Navidad. Métodos: Se tomaron muestras de la ictiofauna con un chinchorro playero a lo largo de un periodo de dos años en cuatro sitios de la laguna. La salinidad y la temperaturadel agua se midieron simultáneamente con las operaciones de muestreo. Se determinaron el tamaño de partículas del sedimento y su contenido de materia orgánica en cuatro momentos a lo largo del periodo de muestreo.Métodos multivariantes fueronutilizados para el análisis de los datos. Resultados: Un total de 13 487 peces pertenecientes a 69 especies fueron recolectados, pero solo cinco taxones(Eucinostomus currani, Mugil setosus, Anchoa sp., Diapterus brevirostris, Centropomus robalito) conformaron más del 80 % de los individuos. Se encontraron diferencias significativas en la composición de la ictiofauna entre todos los sitios de muestreo y entre las estaciones del año. El análisis de redundancia mostró que los cambios en la ictiofauna estuvieron relacionados principalmente con el porcentaje de lodo y el contenido de materia orgánica del sedimento, como expresión de un gradiente espacial. La influencia de la salinidad y la temperatura fue significativa también, pero estas variables explicaron una proporción menor de la variabilidad observada y estuvieron relacionadas principalmente con los cambios estacionales. Conclusiones: El tamaño de las partículas del sedimento y el contenido de materia orgánica del mismo son los factores abióticos más importantes que influyen en los cambios espaciales de la composición de la ictiofauna. Los cambios estacionales estuvieron correlacionados con cambios en la salinidad y la temperatura, pero podrían estar vinculados también a procesos biológicos como la reproducción y el reclutamiento.

Introduction: Coastal lagoons are important habitats for coastal fishes playing an essential role as nursery areas for many species.While the effects of salinity and temperature on fish abundance spatial and temporal variation have been well documented, research on the influence of substrate characteristics is scarce. Objective: To investigatethe correlation of salinity, temperature and sediment characteristics with spatial and temporal variations of the ichthyofauna composition in Barra de Navidad coastal lagoon´s shallow zones. Methods: Samples of ichthyofauna were taken with a beach purse seine along a period of two years in four sites. Water salinity and temperature were measured simultaneously with fish sampling operations. Sediment particle size and organic matter content were determined four times at each site during the sampling period. Multivariate methods were used for data analyses. Results: A total of13 487 fish pertaining to 69 species were collected, but only five taxa (Eucinostomus currani, Mugil setosus, Anchoa sp., Diapterus brevirostris, Centropomus robalito) made up more than 80 % of the individuals. Significant differences among all sampling sites and between seasons were found for the ichthyofauna composition. Redundancy analysis showed that changes in ichthyofaunal composition were mainly related to the percentage of mud and organic matter in sediments expressing a spatial gradient. The influence of salinity and temperature was also significant, but these variables explained a smaller proportion of the observed variability and were related mainly to seasonal changes. Conclusions: Sediment particle size and organic matter content are the most important abiotic factors influencing spatial changes in shallow water ichthyofaunal composition. Seasonal changes were correlated with changes in salinity and temperature but could also be related to biological processes such as reproduction and recruitment.

Comparative analysis of the diet composition and its relation to morphological characteristics in Achirus mazatlanus and Syacium ovale (Pleuronectiformes: Osteichthyes) from a Mexican Pacific coastal lagoon

The purpose of this research was to investigate differences in diet composition between Achirus mazatlanus and Syacium ovale, two flatfishes inhabiting in a tropical coastal lagoon and to investigate the relationship of their feeding habits to size, body morphometry and mouths characteristics. Fish were collected during sampling trips conducted regularly from 2011 to 2016 using several types of fishing gear. Total number of analyzed stomachs with some food content was 328 for Achirus mazatlanus from 1.4 to 21.3 cm total length (TL) and 203 for Syacium ovale with 1.3 to 24.0 cm TL. Results indicate that both species share a general diet based on benthic invertebrates and fishes but S. ovale has a more piscivorous habit, which can be explained by a more slender body shape and larger teeth, characteristics which increase prey fish catching performance. Important changes in composition of food categories related to size were not found for any species, but larger fish of both species eat larger ranges of prey sizes, and this ontogenetic change is consistent with recent developments on optimal foraging theory.(AU)

Se investigaron las diferencias en la composición de la dieta entre Achirus mazatlanus y Syacium ovale, dos especies de lenguados que habitan en una laguna costera tropical, y la relación de los hábitos alimentarios con el largo total, la morfometría corporal y las características de las bocas. Los peces fueron colectados regularmente entre 2011 y 2016, mediante varios tipos de artes de pesca diferentes. El número total de estómagos analizados con contenido estomacal fue de 328 para Achirus mazatlanus de 1.4 a 21.3 cm de longitud total (TL) y 203 para Syacium ovale de 1.3 a 24.0 cm TL. Los resultados indican que ambas especies tienen una dieta general basada en invertebrados bentónicos y peces, pero S. ovale tiene un hábito más piscívoro, lo cual puede ser explicado por un cuerpo más alargado y dientes más grandes, características ambas que incrementan el rendimiento de la captura de peces presas. No se encontraron cambios importantes en la composición de las categorías alimentarias relacionados con la talla en ninguna de las especies de lenguados, pero los peces mayores de ambas especies consumen rangos más amplios de tamaños de presas y este cambio ontogénico es consistente con la teoría de forrajeo óptimo.(AU)

Evidence for protection of targeted reef fish on the largest marine reserve in the Caribbean.

Marine reserves can restore fish abundance and diversity in areas impacted by overfishing, but the effectiveness of reserves in developing countries where resources for enforcement are limited, have seldom been evaluated. Here we assess whether the establishment in 1996 of the largest marine reserve in the Caribbean, Gardens of the Queen in Cuba, has had a positive effect on the abundance of commercially valuable reef fish species in relation to neighboring unprotected areas. We surveyed 25 sites, including two reef habitats (reef crest and reef slope), inside and outside the marine reserve, on five different months, and over a one-and-a-half year period. Densities of the ten most frequent, highly targeted, and relatively large fish species showed a significant variability across the archipelago for both reef habitats that depended on the month of survey. These ten species showed a tendency towards higher abundance inside the reserve in both reef habitats for most months during the study. Average fish densities pooled by protection level, however, showed that five out of these ten species were at least two-fold significantly higher inside than outside the reserve at one or both reef habitats. Supporting evidence from previously published studies in the area indicates that habitat complexity and major benthic communities were similar inside and outside the reserve, while fishing pressure appeared to be homogeneous across the archipelago before reserve establishment. Although poaching may occur within the reserve, especially at the boundaries, effective protection from fishing was the most plausible explanation for the patterns observed.

Influence of sediment granulometry and salinity on the composition of an estuarine fish assemblage in the Mexican Tropical Pacific / Influencia de la granulometría del sedimento y la salinidad en la composición de una comunidad de peces estuarinos en el Pacífico tropical mexicano

Abstract Barra de Navidad lagoon (BNL) is one of the main coastal wetlands in the coast of the State of Jalisco, Mexico. It is a Ramsar site (wetland of international importance) and has been included among the 81 mangrove sites with biological relevance and ecological rehabilitation needs in Mexico. Although fish fauna composition is well known in BNL, little evidence exists that support seasonal and spatial changes of fish assemblages' structure. The hypothesis tested in this study was that there are significant seasonal and spatial changes in BNL fish assemblages' composition which can be explained, at least partially, by changes in salinity, water temperature and sediment's granulometry. Fish assemblages were sampled monthly from October 2012 to September 2013 at four zones of BNL, using gill nets (7.62 mm stretched mesh). A sample was taken every month in a randomly selected area of each zone. Prior to each sampling operation, water salinity and temperature were measured using an YSI-30 probe. Samples of sediment were collected with a Van Veen grab sampler in three randomly selected points of each zone for granulometry and organic matter analyses. A total of 2 026 individuals belonging to 48 species were collected. Slightly more than 90 % of all caught fish belonged to nine species: Peruvian mojarra (Diapterus brevirostris), Pacific crevalle-jack (Caranx caninus), White mullet (Mugil curema), Blue sea-catfish (Ariopsis guatemalensis), Oval flounder (Syacium ovale), Pacific lined sole (Achirus mazatlanus), Yellowfin mojarra (Gerres simillimus), Pacific bumper (Chloroscombrus orqueta) and Freckled porcupinefish (Diodon holocanthus). Generalized linear models yielded significant differences among zones for the mean abundance of each of these nine species, but only in two cases seasonal differences were significant (D. brevisrostris and C. caninus). Permutational multivariate analysis of variance yielded also significant differences among zones and between seasons for the composition of the fish assemblage. Redundancy analysis using salinity, temperature, and percentage mud in sediment as environmental variables showed that fish assemblage's composition varies along two main gradients defined by mud fraction of sediments in a small spatial scale (~ 3 km) and salinity in a seasonal scale. Percentage of variation explained by canonical axes was less than 25 %, indicating that other factors could be influencing changes in assemblage composition. As most species appear as juveniles in the lagoon, fluctuations in their abundances could be linked, at least partially, with recruitment events. Rev. Biol. Trop. 66(3): 1065-1077. Epub 2018 September 01.

Resumen La laguna Barra de Navidad (LBN) es uno de los principales humedales costeros en la costa del Estado de Jalisco, México. Es un sitio Ramsar (humedal de importancia internacional) y ha sido incluida entre los 81 sitios de manglar con relevancia biológica y necesidades de rehabilitación en México. Aunque la composición de la ictiofauna es bien conocida en LBN, hay poca evidencia sobre la existencia de cambios estacionales y espaciales en la estructura de la misma. La hipótesis que guió este trabajo fue que en la composición de la ictiofauna de la laguna Barra de Navidad hay cambios espaciales y estacionales que pueden ser explicados, al menos parcialmente, por cambios en la salinidad, temperatura del agua y granulometría del sedimento. Los peces fueron muestreados mensualmente de octubre 2012 a septiembre 2013 en cuatro zonas de la laguna, usando redes agalleras (7.62 mm de malla estirada). Se tomó una muestra cada mes en un área seleccionada aleatoriamente en cada zona. Previo a cada operación de muestreo, se midieron la salinidad y la temperatura del agua con una sonda YSI-30. Muestras de sedimento para análisis granulométrico y del contenido de materia orgánica, se recolectaron con una draga tipo Van Veen en tres puntos seleccionados aleatoriamente en cada zona. Se recolectaron 2 026 individuos de 48 especies de peces. Poco más de 90 % de todos los peces contados pertenecieron a nueve especies: Diapterus brevirostris, Caranx caninus, Mugil curema, Ariopsis guatemalensis, Syacium ovale, Achirus mazatlanus, Gerres simillimus, Chloroscombrus orqueta y Diodon holocanthus. Modelos lineales generalizados arrojaron diferencias significativas entre zonas para la abundancia media de estas nueve especies, pero solo en dos casos se encontraron diferencias significativas entre estaciones (D. brevirostris y C. caninus). El análisis multidimensional de varianza basado en permutaciones, arrojó también diferencias significativas entre zonas y entre estaciones para la composición de la ictiofauna. El análisis de redundancia usando la salinidad, la temperatura y el porcentaje de lodo en el sedimento como variables ambientales, mostró que la composición de la ictiofauna varía a lo largo de dos gradientes definidos por la fracción de lodo de los sedimentos en una escala espacial pequeña (~ 3 km) y la salinidad en una escala estacional. El porcentaje de variación explicado por los ejes canónicos fue menor de 25 %, indicando que otros factores pudieran influir en los cambios de la composición de la ictiofauna. Como la mayoría de las especies aparecen en su estadio juvenil en la laguna, las fluctuaciones en sus abundancias pudieran estar relacionadas, al menos parcialmente, con eventos de reclutamiento.

Diversidad de las comunidades de peces en dos áreas marinas protegidas del Caribe y su relación con el pez león / Diversity of native reef fish communities in two protected areas in the Caribbean Sea and its relationship to the invasive lionfish

Resumen El pez león (Pterois volitans) invadió la región del Caribe y tiene el potencial de alterar la composición y estructura de las comunidades de peces en los arrecifes coralinos. El objetivo de este estudio fue analizar los índices de diversidad en las comunidades de peces nativos en sitios invadidos por el pez león en dos áreas marinas protegidas (AMP) del Caribe y compararlos con datos previos a la invasión. En ambas AMP, Parque Nacional Guanahacabibes (PNG) en el occidente de Cuba y Parque Nacional Arrecifes de Xcalak (PNAX) en el S de Quintana Roo, se realizaron censos visuales de las especies de peces en hábitats durante las épocas de seca y lluvia del 2013-2015. Se evaluaron nueve sitios, mediante conteos estacionarios. Se registró mayor riqueza de especies en el PNG (43.47±5.14) que en el PNAX (40.22±4.96). No se observaron diferencias entre épocas en ninguna de las AMP. El pez león se ubicó entre las especies más abundantes del PNG. La abundancia media en el PNG (0.76 ± 1.25) fue mayor a la registrada en el PNAX (0.19±0.46). La diversidad disminuyó después de la llegada del pez león en un solo sitio del PNG y en dos sitios del PNAX, pero al parecer estos resultados están más asociados al efecto de la pesca que a la presencia del pez león. A partir de los resultados y asumiendo que los cambios en las comunidades de peces por el pez león podrían no detectarse aún, recomendamos seguir los monitoreos de los descriptores comunitarios para detectar cambios futuros en las comunidades de peces.

Abstract Lionfish (Pterois volitans) invaded the Caribbean region with the potential to alter the composition and structure of native coral reef fish communities. The objective of this study was to analyze the diversity indices of these fish communities potentially affected by lionfish predation and to compare with pre-invasion data. The study was undertaken in two Caribbean marine protected areas (MPAs): Guanahacabibes National Park (PNG) in W Cuba and Xcalak Reefs National Park (PNAX) in S Quintana Roo. We carried out visual censuses of fish species in reef habitats during the dry and rainy seasons of the period 2013-2015. For this, nine sites were defined and evaluated using stationary counts. Our results showed higher species richness (43.47 ± 5.14) and mean abundance (0.76 ± 1.25) in PNG than in PNAX (40.22 ± 4.96, 0.19 ± 0.46, respectively). Diversity decreased after the arrival of lionfish in a single site of PNG and in two sites of the PNAX, but apparently, these results are more related to the fishing activity effect than to the lionfish presence. Based on the results and assuming that changes in the native fish communities by lionfish may not yet be detected, we recommend to continue the monitoring community descriptions in order to detect future changes in native fish communities. Rev. Biol. Trop. 66(1): 189-203. Epub 2018 March 01.