Characterization of a Peruvian coastal fishery targeting the Pacific guitarfish Pseudobatos planiceps.

From December 2012 to June 2014, 796 Pacific guitarfish were caught in 183 fishing sets in northern Peru. Catch occurred in 86.3% of sets. Most individuals caught were mature with a bias toward males. The mean total length for females and males was 83.4 cm, and 91.1 cm, respectively. The capture per unit effort (CPUE) was 12.6 ± 3.4 guitarfish (km.12 h)-1. The length-weight relationships showed that this species presents a sexual dimorphism in growth. These results support the importance of Sechura Bay as a key area for this species. This study represents the first species-specific fishery data for the Pacific guitarfish.

Abundancia, densidad y estructura de tallas de Mellitella stokesii (Echinolampadacea: Mellitidae) en playones del estero El Tamarindo, El Salvador / Abundance, density and size structure of Mellitella stokesii (Echinolampadacea: Mellitidae) in sandbanks of El Tamarindo estuary, El Salvador

Resumen Introducción: Los equinoideos irregulares se caracterizan por tener una selección del sustrato en fondos blandos principalmente. En El Salvador se han registrado siete especies de equinoideos irregulares en las principales playas arenosas del país, M. stokesii es una de ellas. Objetivo: Determinar la abundancia, densidad y estructura de tallas, en playones de la bocana del estero El Tamarindo, El Salvador. Métodos: La investigación se realizó en época seca en el oriente del país en playones del estero El Tamarindo que se caracteriza por presentar grandes extensiones de arena mezclada con materia orgánica. En cada sitio, se trazaron transectos en banda paralelos a la costa mediante 9 cuadrantes de 10 m2 separados entre sí por 10 m (área total de 90 m2), en donde se contabilizaron y midieron los individuos de M. stokesii que se encontraran dentro del área delimitada. Resultados: Se contabilizaron 958 individuos de M. stokesii con una densidad total de 10.64 ± 13.22 ind/m2. El rango de tamaños fue de 1-6.5 cm. El hábitat se caracterizó por presentar arena con materia orgánica en los primeros mm del sustrato en compañía de otros invertebrados. Conclusiones: La abundancia y densidad de M. stokesii es similar a la registrada en otros estudios de la región.

Abstract Introduction: Irregular echinoids are characterized by having a selection of the substrate mainly on soft bottoms. In El Salvador, seven species of irregular echinoids have been recorded on the main sandy beaches of the country, M. stokesii is one of them. Objective: Determine the abundance, density and size structure of M. stokesii on beaches at the mouth of the El Tamarindo estuary, El Salvador. Methods: The research was carried out in the dry season in the east of the country on the beaches of the El Tamarindo estuary, which is characterized by large extensions of sand mixed with organic matter. At each site, band transects parallel to the coast were plotted by 9 quadrants of 10 m2 separated from each other by 10 m (total area of 90 m2), where individuals of M. stokesii found within the delimited area were counted and measured. Results: 958 individuals of M. stokesii were counted with a total density of 10.64 ± 13.22 ind/m2. The size range was 1-6.5 cm. The habitat was characterized by presenting sand with organic matter in the first mm of the substrate in the company of other invertebrates. Conclusions: The abundance and density of M. stokesii are similar to the ones recorded in other studies in the region.

Variabilidad en el tamaño y alimentación de Acanthaster planci (Echinodermata: Asteroidea) en el sur del Golfo de California, México / Variability of size and food type of Acanthaster planci (Echinodermata: Asteroidea) in the southern Gulf of California, Mexico

Introducción: Es poco lo que se conoce sobre aspectos biológicos y poblacionales de Acanthaster planci en México. Su tamaño se ha relacionado con la cantidad de alimento que consume, por lo que es relevante conocer esta variable. Objetivo: Describir la variabilidad en el diámetro del disco de la especie y de su alimentación en cuatro sitios al sur del Golfo de California. Métodos: De febrero 2008 a marzo 2009 se visitaron mensualmente los sitios. Se registró el diámetro del disco de un total de 389 individuos observados. El diámetro del disco se midió con una cinta métrica flexible colocada de lado a lado, en el borde donde comienzan los brazos. Para facilitar la descripción, el diámetro del disco se clasificó en tres grupos: pequeños ( 26 cm). Del total, 298 organismos se encontraron alimentándose. Se clasificaron los tipos de organismos consumidos en corales duros, otros invertebrados y algas. Para calcular la probabilidad de que individuos del mismo tamaño se alimenten de diferente variedad de organismos, se aplicó el índice de Diversidad de Simpson. Con el fin de detectar diferencias del diámetro del disco entre los meses de estudio y los sitios de muestreo, se aplicó un análisis permutacional de varianza. Resultados: Acanthaster planci tuvo un promedio de diámetro del disco de 18.23 ± 0.21 cm, con un mínimo de 7 cm y un máximo de 36 cm. La estructura de tallas fue unimodal y se caracterizó por la predominancia de individuos medianos, seguida por los pequeños y en baja proporción por los grandes. El diámetro del disco fue estadísticamente más grande en febrero y más pequeño en los últimos meses del año. En San Rafaelito se encontraron los ejemplares más grandes y en Ensenada de Muertos los más pequeños. Los individuos de tamaño mediano fueron más frecuentes a lo largo del año y en todos los sitios. Los individuos pequeños se alimentaron significativamente más de Porites panamensis, seguido de algas coralinas y tapetes. Los más grandes tuvieron los valores de diversidad más bajos, más del 90 % de los individuos en este grupo se alimentaron de Pocillopora spp. y algunos de macroalgas. Los medianos presentaron los valores más altos de diversidad y consumieron todos los tipos de alimento encontrados, sin embargo, como era de esperarse, muchos fueron selectivos hacia Pocillopora spp. Conclusiones: Acanthaster planci se considera un individuo de tamaño mediano en el área de estudio. Se detectó una evidente relación entre el diámetro del disco y la diversidad del tipo de alimento. Los tres grupos de tallas fueron positivamente selectivos hacia corales duros; los más pequeños se alimentaron preferentemente de Porites panamensis y en conjunto con los grandes, presentaron valores bajos de diversidad en el tipo de alimento, mientras que los medianos fueron los que consumieron una mayor diversidad de presas.

Introduction: Little is known about the biology and population dynamics of Acanthaster planci in Mexico. Its size is considered relevant because it is related to consumption rate. Objective: To describe the variability of the disk diameter and food type of the species in four sampling sites in the southern Gulf of California. Methods: Each site was visited on a monthly basis from February 2008 to March 2009. Disk diameter was registered from a total of 389 observed specimens. Measurements included only the main disk from side to side where the arms begin. A flexible tape was used to measure disk diameter. Three size groups were created for easier explanations: small ( 26 cm). From the total, only 298 asteroids were feeding. Preyed organisms were classified in hard corals, other invertebrates, and algae. The Simpson's Diversity Index was used to calculate the probability that any specimen would be feeding on different types of organisms. A permutational analysis of variance was used to detect differences of disk diameter amongst months and study sites. Results: This population of Acanthaster planci had an average disk diameter = 18.23 ± 0.21 cm, with a minimum of 7 cm and maximum of 36 cm. Size structure was unimodal and largely dominated by medium sized specimens, followed by small ones. The larger were less frequent. Disk diameter was statistically higher in February and lower in the last months of the year. San Rafaelito was the site with the largest and Ensenada de Muertos with the smallest organisms. Medium sized individuals were dominant throughout the year and sampling sites. The small sized fed significantly more on Porites panamensis and coralline algae and turf. Larger specimens had the lowest diversity values, more than 90 % of this size group fed on Pocillopora spp. and very few on macroalgae. Medium sized specimens showed the highest diversity, feeding on all the food types, although as expected, many of them were selective to Pocillopora spp. Conclusions: Acanthaster planci can be considered a medium sized species in the study area. There is an evident food selectivity regarding disk diameter size. The three size groups were positively selective to hard corals, but only the small favored Porites panamensis; and together with large individuals, they had the lowest diversity on food types, whereas medium sized asteroids fed on a high diversity of prey.

Drivers of phytoplankton production and community structure in nutrient-poor estuaries receiving terrestrial organic inflow.

The influence of nutrient availability and light conditions on phytoplankton size-structure, nutritional strategy and production was studied in a phosphorus-poor estuary in the northern Baltic Sea receiving humic-rich river water. The relative biomass of mixotrophic nanophytoplankton peaked in spring when heterotrophic bacterial production was high, while autotrophic microphytoplankton had their maximum in summer when primary production displayed highest values. Limiting substance (phosphorus) only showed small temporal variations, and the day light was at saturating levels all through the study period. We also investigated if the phytoplankton taxonomic richness influences the production. Structural equation modelling indicated that an increase of the taxonomic richness during the warm summer combined with slightly higher phosphorus concentration lead to increased resource use efficiency, which in turn caused higher phytoplankton biomass and primary production. Our results suggest that climate warming would lead to higher primary production in northerly shallow coastal areas, which are influenced by humic-rich river run-off from un-disturbed terrestrial systems.

Seagrass Halodule wrightii as a new habitat for the amphioxus Branchiostoma californiense (Cephalochordata, Branchiostomidae) in the southern Gulf of California, Mexico.

The first record of the amphioxus Branchiostoma californiense on seagrass patches of Halodule wrightii in the Gulf of California is reported. Sixty individuals (19 males, 18 females, and 23 undifferentiated) were collected in May 2017 at Bahía Balandra, Gulf of California, from subtidal seagrass patches at a depth of 0.5 m at low tide. The length and weight ranged from 15.88-28.44 mm and from 0.01-0.11 g for females and 11.7-27.9 mm and 0.01-0.09 g for males, respectively. The minimum size of sexually mature individuals was 11.70 mm for males and 15.88 mm for females; 62% of the specimens were sexually mature. Analysis of the total length-weight relationship suggested an allometric growth pattern among females, males and undifferentiated individuals, whereas an analysis of the entire sample suggested an isometric growth pattern. Typical and additional morphological characters were used to identify the amphioxi. High morphological variability between individuals was found, suggesting the presence of several morphotypes. Branchiostoma californiense had been previously reported as exclusively associated with bare sandy areas, but our study shows that this species can also be found in seagrass patches, using them as breeding and feeding grounds. Thus, seagrass patches are evidenced as suitable habitats for amphioxus.

Population structure and reproductive cycle of the commercial sea cucumber Holothuria mexicana (Echinodermata: Holothuroidea) in Belize / Estructura de la población y ciclo reproductivo del pepino de mar comercial Holothuria mexicana (Echinodermata: Holothuroidea) en Belice

Abstract The population and reproductive biology of the commercial sea cucumber Holothuria mexicana (Ludwig, 1875) was studied in Southern Belize (Caribbean Sea), including the sex ratio, size at sexual maturity and reproductive cycle, as well as the size structure among habitats located inside and outside protected areas. Individuals found inside marine protected areas were consistently larger than individuals found outside these boundaries. The male:female sex ratio was 1.1:1.0 with a unimodal size distribution composed mainly of sexually mature individuals (87 %). Size at sexual maturity was established to be ~10 cm based on measures of gamogenetically mature individuals during the peak of the gametogenic maturity period. Juveniles and small adults measuring ≤ 15 cm (13 %), were collected exclusively in sandy and muddy areas of seagrass habitats associated with mangroves. Larger adults were commonly found on hard substrates in both seagrass-associated and coral-reef-associated habitats. Based on histology and gonad indices, the first sign of early gametogenesis was detected in August in both sexes. Gametes developed and matured throughout the colder months between November and February. Decreases in gonad index in both years suggest annual spawning, starting in MarchApril 2014 (single major event) and March-April and July-August 2015 (two smaller events) for both males and females. The spawning periods were correlated with warmer or increasing temperatures, low rainfall and increasing or high chlorophyll-a concentrations. These data will hopefully guide management and protection of the natural populations of H. mexicana, which are already suffering from overfishing in Belize and neighboring countries.(AU)

Resumen La población y la biología reproductiva de pepino de mar comercial Holothuria mexicana (Ludwig, 1875) fue estudiado en el sur de Belice (Mar Caribe), incluyendo la proporción de sexo, talla de madurez sexual y el ciclo reproductivo, así como la estructura de tamaño entre hábitats situados dentro y fuera de áreas marinas protegidas. Los individuos dentro de las áreas marinas protegidas fueron siempre mayores que los individuos encontrados fuera de estos límites. La proporcion de machos a hembras fue de 1.1:1.0, con una distribución de tamaño unimodal compuesta principalmente de individuos sexualmente maduros (87 %). La talla de madurez sexual fue ~10 cm basada en medidas de individuos con gametos maduros durante el período del pico de maduracion de gametos. Los juveniles y adultos pequeños de medidas ≤ 15 cm (13.1 %), fueron recogidos exclusivamente en zonas fangosas y arenosas en pastos marinos asociados con los manglares. Los adultos mayores se encontraban comúnmente sobre substratos duros tanto en pastos marinos asociados como en los arrecifes de coral. Basada en la histología y gónada de índices, el primer signo de la gametogénesis temprana fue detectado en Agosto en ambos sexos. Los gametos en desarrollo y maduros se encontraron durante los meses fríos entre Noviembre y Febrero. Las disminuciones en el índice gonadal en ambos años sugieren desove anual, el cual comenzó en Marzo y Abril de 2014 (único gran evento) y en Marzo-Abril y Julio-Agosto de 2015 (dos pequeños eventos) tanto para ambos sexos durante temperaturas más cálidas, escasas precipitaciones y altas concentraciones de clorofila-a. Con estos datos esperamos orientar la gestión y la protección de las poblaciones naturales de H. mexicana, que ya están sufriendo los efectos de la sobrepesca en Belice y países vecinos.(AU)

Size, growth, and density data for shallow-water sea urchins from Mexico to the Aleutian Islands, Alaska, 1956-2016.

Size, growth, and density have been studied for North American Pacific coast sea urchins Strongylocentrotus purpuratus, S. droebachiensis, S. polyacanthus, Mesocentrotus (Strongylocentrotus) franciscanus, Lytechinus pictus, Centrostephanus coronatus, and Arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956 to present. Numerous peer-reviewed publications have used some of these data but some data have appeared only in graduate theses or the gray literature. There also are data that have never appeared outside original data sheets. Motivation for studies has included fisheries management and environmental monitoring of sewer and power plant outfalls as well as changes associated with disease epidemics. Studies also have focused on kelp restoration, community effects of sea otters, basic sea urchin biology, and monitoring. The data sets presented here are a historical record of size, density, and growth for a common group of marine invertebrates in intertidal and nearshore environments that can be used to test hypotheses concerning future changes associated with fisheries practices, shifts of predator distributions, climate and ecosystem changes, and ocean acidification along the Pacific Coast of North America and islands of the north Pacific. No copyright restrictions apply. Please credit this paper when using the data.

La estructura de tallas como evidencia del establecimiento de Pterois volitansScorpaeniformes: Scorpaenidae) en el sur del Caribe mexicano / Size structure as evidence of population establishment of Pterois volitans (Scorpaeniformes: Scorpaenidae) in the South Mexican Caribbean

ResumenEl pez león (P. volitans), ha invadido todo el Caribe mexicano y Golfo de México, con un potencial de causar impactos negativos en el arrecife. En el sur del Caribe Mexicano se registró por vez primera en julio 2009, y a seis años del primer reporte, se han implementado algunas medidas de control como torneos de pesca y su comercialización local. No obstante, la información sobre su biología e inicio de invasión aún es escasa, por lo que este estudio analizó la estructura poblacional de 2 164 organismos recolectados entre 2009 y 2012, un incremento en las tallas para cada año fue observado, con promedios de Longitud Total (Lt): 118 ± 34.8, 133 ± 56.3, 187 ± 74.8 y 219 ± 72.4 mm respectivamente. El establecimiento del pez león en el área de estudio es demostrado por la presencia de tallas juveniles (20 mm Lt) hasta organismos de 375 mm Lt. Al realizar el retrocálculo de las longitudes obtenidas se estimó que el organismo de mayor talla pudo reclutarse a principios del 2006, tres años antes del primer reporte. Un monitoreo continuo de la población así como un estudio ecológico, nos permitirá dilucidar el impacto real en los ecosistemas de la región y así proponer las medidas de control más efectivas.

AbstractThe lionfish (P. volitans) has now invaded all the Mexican Caribbean and Gulf of Mexico, with the potential to cause negative impacts on the reefs. In the South Mexican Caribbean was firstly reported in July 2009, and six years after this report, some control measures such as fish tournament and local marketing have been implemented. However, information on its biology and invasion is still-lacking, so this study analyzed the population structure of 2 164 organisms collected from 2009 to 2012. An increase was observed in sizes for each year averaging Total length (Tl): 118 ± 34.8, 133 ± 56.3, 187 ± 74.8 and 219 ± 72.4 mm, respectively. Lionfish establishment at the study site is shown for the presence of juveniles' sizes 20 mm TL up to 375 mm TL. When the back-calculation was obtained, we estimated that the larger fish could have recruited in early 2006, three years before the first report was made. A continuous population monitoring and an ecological study, will allow us to clarify the real impact in the ecosystems of the region and so to propose the most effective control actions. Rev. Biol. Trop. 64 (1): 353-362. Epub 2016 March 01.

Temporal stability of an endemic Mexican treefrog.

The demographic characteristics of an amphibian population fluctuate independently over time, mainly in response to the temporal variation of environmental factors, especially precipitation and temperature. These temporal fluctuations may contribute to the size of an amphibian population and could be used to determine the current conservation status of a species. During a five year (2004-2008) period, we studied the relative abundance, sex ratio, and age-sex structure of a population of metamorphosed individuals of the endemic treefrog Hyla eximia in Central Mexico. We also studied the species' relationship with climatic variables such as temperature and precipitation. We found an interannual constant abundance during the study period. However, interannual differences were observed in the population structure by age-sex category (males, females, or juveniles), with decreased abundance of males and juveniles during the rainy months (August-November). The annual abundance of H. eximia was positively correlated with rainfall, but negatively with monthly temperature. We found the sex ratio was male-biased (2:1), except for year 2008. Also, differences in snout-vent length (SVL) were found between years, suggesting changes in recruitment of new individuals. We conclude that variations in abundance, and frequencies by age-sex category, of H. eximia are related to seasonal variations in temperature and precipitation characteristics of temperate zones. However, this temporal stability may suggest that anurans have an unusual capacity to persist even in the face of human-induced habitat change.

Population size-structure-dependent fitness and ecosystem consequences in Trinidadian guppies.

Decades of theory and recent empirical results have shown that evolutionary, population, community and ecosystem properties are the result of feedbacks between ecological and evolutionary processes. The vast majority of theory and empirical research on these eco-evolutionary feedbacks has focused on interactions among population size and mean traits of populations. However, numbers and mean traits represent only a fraction of the possible feedback dimensions. Populations of many organisms consist of different size classes that differ in their impact on the environment and each other. Moreover, rarely do we know the map of ecological pathways through which changes in numbers or size structure cause evolutionary change. The goal of this study was to test the role of size structure in eco-evolutionary feedbacks of Trinidadian guppies and to begin to build an eco-evolutionary map along this unexplored dimension. We used a factorial experiment in mesocosms wherein we crossed high- and low-predation guppy phenotypes with population size structure. We tested the ability of changes in size structure to generate selection on the demographic rates of guppies using an integral projection model (IPM). To understand how fitness differences among high- and low-predation phenotypes may be generated, we measured the response of the biomass of lower trophic levels and nutrient cycling to the different phenotype and size structure treatments. We found a significant interaction between guppy phenotype and the size structure treatments for absolute fitness. Size structure had a very large effect on invertebrate biomass in the mesocosms, but there was little or no effect of the phenotype. The effect of size structure on algal biomass depended on guppy phenotype, with no difference in algal biomass in populations with more, smaller guppies, but a large decrease in algal biomass in mesocosms with phenotypes adapted to low-predation risk. These results indicate an important role for size structure partially driving eco-evolutionary feedbacks in guppies. The changes in the ecosystem suggest that the absence of a steep decline in guppy fitness of the low-predation risk populations is likely due to higher consumption of algae when invertebrates are comparatively rare. Overall, these results demonstrate size structure as a possible dimension through which eco-evolutionary feedbacks may occur in natural populations.

Eutrophication effects on phytoplankton size-fractioned biomass and production at a tropical estuary.

Size-fractioned phytoplankton (pico, nano and microplankton) biomass and production were estimated throughout a year at Recife harbor (NE Brazil), a shallow well mixed tropical hypereutrophic estuary with short residence times but restricted water renewal. Intense loads of P-PO4 (maximum 14 µM) resulted in low N:P ratios (around 2:1), high phytoplankton biomass (B=7.1-72 µg chl-a L(-1)), production (PP=10-2657 µg C L(-1) h(-1)) and photosynthetic efficiency (P(B)=0.5-45 µg C µg chl-a(-1)), but no oxygen depletion (average O2 saturation: 109.6%). Nanoplankton dominated phytoplankton biomass (66%) but micro- and nanoplankton performed equivalent primary production rates (47% each). Production-biomass models indicate an export of the exceeding microplankton biomass during most of the year, possibly through grazing. The intense and constant nutrient and organic matter loading at Recife harbor is thus supporting the high microplankton productivity that is not accumulating on the system nor contributing to oxygen depletion, but supporting the whole system's trophic web.

Variabilidad en la abundancia relativa, estructura por tallas y proporción de sexos del dorado Coryphaena hippurus (Pisces: Coryphaenidae) en el Golfo de Tehuantepec, México / Variability in the relative abundance, size structure and sex ratio of the dolphinfish Coryphaena hippurus (Pisces: Coryphaenidae) in the Gulf of Tehuantepec, México

The dolphinfish (Coryphaena hippurus), is an oceanic epipelagic fish found worldwide in tropical and subtropical waters, with a high dispersal capability via large-scale migrations. This fast-swimming top-level predator is abundant in the Gulf of Tehuantepec, where it is caught incidentally by artisanal fisheries, and represents a target species for both recreational and commercial fisheries in Mexico, Ecuador, Peru and Central America. Nowadays, local fishery information on this species is scarce, thus our objective was to analyze the size structure by sex and the catch-per-unit-effort (CPUE) tendency of dolphinfish caught in the Gulf of Tehuantepec, from 2000 to 2007. For this, fishery catches information was obtained from the artisanal fleet, at six landing sites in the Gulf, and the sex ratio, fork length (FL) and the catch per unit effort (CPUE) were estimated. From all sampling sites, a total of 3 494 females, and 3 877 males were obtained, and dolphinfish size as fork length (FL) ranged from 20.5 to 152cm. Fish size ranged from 25.5 to 148cm furcal length (FL) in males, and 20.5 to 129cm FL in females. The sex ratio (males:females) was 1:1, except in April-May (1:1.5, p<0.05) and November (1:0.5, p<0.05). The sex ratio at different size classes showed a significant bias towards females at smaller sizes (<75cm FL), whereas the males were predominant in larger size classes (>100cm FL). The size structure was bimodal, with a variation in the size average; the modes were defined as the small group (FL=50-55cm) and the large size group (FL=100-110cm). The CPUE showed seasonal changes: values were high for the November-December period, and values were lower for July-August. The seasonal and inter annual variation in the abundance of dolphinfish is probably related to a pre-spawning migration in close relation to the rain-drought regime characteristic of the region, and the associated wind upwelling season of “Tehuanos” in the Gulf of Tehuantepec. Rev. Biol. Trop. 62 (2): 611-626. Epub 2014 June 01.

El dorado Coryphaena hippurus es un depredador oceánico epipelágico que se distribuye en aguas tropicales y subtropicales de todos los océanos. Son peces con alta capacidad de dispersión por su migración a gran escala. El Golfo de Tehuantepec es una de las áreas de mayor abundancia de C. hippurus, donde se registran capturas incidentales en la pesca artesanal y sostiene pesquerías recreacionales y comerciales de pequeña escala en México, Ecuador, Perú y Centroamérica. Aquí se analizan los cambios inter-anuales en la estructura de tallas por sexo del dorado durante 2000-2007, así como la tendencia de la captura por unidad de esfuerzo (CPUE) de dorado efectuada por la flota ribereña. Los resultados están basados en 3 494 hembras y 3 877 machos capturados por pesca artesanal en 6 localidades del Pacífico Sur provenientes de muestreos mensuales. Se estimó la CPUE a partir del número de organismos capturados por viaje de pesca. Los machos pre- sentaron tallas entre 25.5 a 148cm de longitud furcal (Lf), mientras que en hembras las tallas registradas fueron de 20.5 a 129cm Lf. La proporción de sexos mostró patrones estacionales a lo largo del año y diferencias con respecto de Lf, a tallas pequeñas predominaron las hembras (<75cm FL) y a tallas grandes los machos (>100cm Lf). La estructura de Lf mostró una tendencia bimodal, con una variación en la Lf promedio de 2000 a 2007; las modas estuvieron definidas como el grupo de tamaño pequeño (Lf=50-55cm) y el grupo de tamaño grande (Lf=100 a 110cm). La CPUE tuvo cambios estacionales: los periodos más altos se registraron en noviembre-diciembre y mayo; los más bajos en julio-agosto. La variación estacional e interanual en la abundancia del dorado probablemente se encuentre relacionada con una migración pre desove, en estrecha relación con el régimen lluvias-estiaje característico de la región, y la temporada de surgencias eólicas asociadas a la temporada de “Tehuanos” en el Golfo de Tehuantepec.

Static measurements of the resilience of Caribbean coral populations / Mediciones estáticas de la resiliencia de las poblaciones de coral del Caribe

The progressive downward shift in dominance of key reef building corals, coupled with dramatic increases in macroalgae and other nuisance species, fields of unstable coral rubble ,loss of structural relief, and declines of major functional groups of fishes is a common occurrence throughout the Caribbean today. The incorporation of resilience principles into management is a proposed strategy to reverse this trend and ensure proper functioning of coral reefs under predicted scenarios of climate change, yet ecosystem processes and functions that underlie reef resilience are not fully understood. Rapid assessments using the Atlantic and Gulf Rapid Reef Assessment (AGRRA) and the IUCN Resilience Assessment protocol can provide baseline information on reef resilience. A key aspect of these surveys focuses on coral population dynamics, including measures of coral cover, size, partial and whole-colony mortality, condition, and recruitment. One challenge is that these represent static measures involving a single assessment. Without following individual corals over time, it is difficult to determine rates of survival and growth of recruits and adult colonies, and differentiation of juveniles from small remnants of older colonies may not be possible, especially when macroalgal cover is high. To address this limitation, corals assessed in Bonaire in July 2010 were subdivided into two categories: 1) colonies on the reef substrate; and 2) colonies colonizing dead corals and exposed skeletal surfaces of living corals. Coral populations in Bonaire exhibited many features indicative of high resilience, including high coral cover (often 30-50%), high levels of recruitment, and a large number of corals that settled on dead corals and survived to larger size-classes. Overall, the skeletal surfaces of 12 species of corals were colonized by 16 species of corals, with up to 12 settlers on each colony, most (67%) on M. annularis (complex) skeletons. Nevertheless, completely dead M. annularis colonies were common, survivors were frequently reduced in size and subdivided into smaller tissue remnants, and these species exhibited higher amounts of partial mortality than all other species. A notable absence of sexual recruits and juveniles of M. annularis illustrates a progressive shift away from a Montastraea dominated system. This shift, characterized by an increasing dominance of smaller, short-lived species such as Agaricia and Porites and a reduction in size of longer-lived massive corals, is occurring throughout the Caribbean. Monitoring of the survival of recruits is necessary to determine whether Caribbean reefs will retain the same function, structure, identity and feedbacks (key signs of resilience) if the losses of M. annularis (complex) continue at present levels. The rapid assessment protocol utilized here allows characterization of colony size structure, partial mortality, recruitment, and whether small corals represent surviving recruits that increased in size or larger (older) colonies that continue to shrink in size. This approach can help determine the history of a site and its resilience.

En la actualidad se está viendo en el Caribe un cambio en la composición de los corales constructores de arrecifes, aumento en la cobertura de macroalgas y otras especies, un aumento en áreas cubiertas por escombros de corales, y una pérdida de relieve. La incorporación de principios de resiliencia en el manejo es una estrategia propuesta para revertir esta tendencia y asegurar la sobrevivencia y el adecuado funcionamiento de los arrecifes de coral bajo escenarios previstos de cambio climático. Sin embargo, todavía quedan grandes vacíos en la comprensión de los factores que promueven la resiliencia. Evaluaciones rápidas realizadas con la metodología AGRRA (Atlantic and Gulf Rapid Reef Assessment) y con el protocolo de Evaluación de Resiliencia para arrecifes coralinos de la IUCN brindan información de línea base sobre la resiliencia de los arrecifes del Caribe. Un aspecto clave de estos estudios se centra en la dinámica de las poblaciones de los corales, incluyendo medidas de cobertura de coral, estructura de tallas, la extensión de la mortalidad parcial y total de toda la comunidad, condición de los corales y reclutamiento. Un reto es que esto representa una medida estática que involucra una única evaluación. Sin seguir las colonias individuales y el reclutamiento en el tiempo, es difícil determinar las tasas de sobrevivencia y crecimiento de los reclutas, y podría no ser posible la diferenciación de los juveniles de los restos pequeños de colonias más viejas, especialmente cuando la cobertura algal es alta. Para abordar esta limitación, los corales monitoreados en Bonaire en julio del 2010 fueron subdivididos en dos categorías: 1) colonias sobre la estructura arrecifal; y 2) colonias creciendo sobre coral muerto o sobre las superficies expuestas del esqueleto de los corales vivos. Los arrecifes en Bonaire exhiben muchas características indicativas de alta resiliencia, incluyendo una alta cobertura de coral (frecuentemente 30-50%), altos niveles de reclutamiento, y un gran número de corales que se asentaron sobre los corales muertos y crecieron. En general, las superficies del esqueleto de 12 especies de corales fueron colonizadas por 16 especies de corales, con un máximo de 12 colonizadores en cada colonia, la mayoría (67%) sobre esqueletos de Montastraea annularis (complejo). Colonias completamente muertas de M. annularis fueron comunes y los sobrevivientes con frecuencia son más pequeños o subdivididos en pequeños restos de tejido. Montastraea annularis es la especie que exhibe una mayor mortalidad parcial en relación con los demás corales. Una notable ausencia de reclutamiento sexual y juveniles de M. annularis ilustra el cambio progresivo de cambio de un sistema dominado por Montastraea. Este cambio, que se está produciendo en todo el Caribe, se caracteriza por un dominio cada vez mayor de especies más pequeñas y de vida corta como Agaricia y Porites, y una reducción en el tamaño de los corales masivos longevos. El seguimiento de la sobrevivencia de los reclutas es necesario para determinar si los arrecifes del Caribe mantendrán la misma función, estructura, identidad y retroalimentación (signos clave de la resiliencia), y si las pérdidas de M. annularis (complejo) continuarán a los niveles actuales. La evaluación rápida presentada aquí posibilita caracterizar la estructura de tamaño de las colonias, los niveles de reclutamiento y determinar si los corales pequeños representan sobrevivientes de colonias que incrementan su tamaño o colonias grandes (más viejas) que siguen disminuyendo de tamaño. Este enfoque puede ayudar a determinar la historia de un sitio y su capacidad de recuperación.

Estrutura e dinâmica da população de Amaioua guianensis Aubl. (Rubiaceae) em fragmento urbano de floresta estacional semidecidual ­ Uberlândia, Minas Gerais / Structure and dynamics of a population of Amaioua guianensis Aubl. (Rubiaceae) in a semideciduous forest urban fragment ­ Uberlândia, Minas Gerais state

A floresta estacional semidecidual do Parque do Sabiá sofreu pressões antrópicas por muitos anos e, desde a eliminação dos fatores de perturbação, estudos sobre a composição florística, estrutura e dinâmica da comunidade arbórea vêm sendo realizados no local para verificar como as populações vegetais estão respondendo às perturbações. Este estudo descreve a estrutura e a dinâmica da população de Amaioua guianensis em uma área de 0,2 ha, na qual todos os indivíduos jovens desta espécie foram medidos em altura e diâmetro e marcados, após as estações chuvosas dos anos de 2008 e 2009. Foram encontrados 151 indivíduos em 2008 e 175 em 2009, totalizando 32 recrutamentos e oito mortes no ano de 2009, correspondendo às taxas de mortalidade de 5,3% e recrutamento de 21,2%. Os indivíduos se distribuíram de forma agrupada. A estrutura populacional, representada pelas medidas de altura e diâmetro, apresentou a forma de "J" invertido, caracterizando uma população estável quanto à distribuição dos indivíduos, mas em expansão devido à alta taxa de recrutamento. A população parece estar se regenerando satisfatoriamente na área e necessita de acompanhamento de longo prazo para detectar um possível domínio desta espécie na comunidade.

The semideciduous forest in Sabia Park had suffered anthropogenic pressures for many years and since the elimination of disturbing factors, studies on floristic composition, structure and tree community dynamics has been carried out on site to see how the local plant populations are responding to these changes. The aim of this study was to describe the structure and dynamics of Amaioua guianensis population in an area of 0.2 ha, where all regenerating individuals of this species were measured for height and diameter and marked, after the rainy season of the years 2008 and 2009. It was found 151 individuals in 2008 and 175 in 2009, which totalized 32 recruits and eight deaths in 2009 and mortality and recruitment rates of 5.3% and 21.2%, respectively. Individuals were distributed in an aggregated manner. Population structure, represented by the measures of height and diameter, showed the shape of inverted "J", featuring a stable population on the distribution of individuals, but expanding due to the high rate of recruitment. The population seems to be regenerating successfully in the area and need long-term monitoring to detect a possible dominance of this species in the community

Abundance, distribution and size structure of Diadema antillarum (Echinodermata: Diadematidae) in South Eastern Cuban coral reefs

The 1983-1984 mass mortality event of Diadema antillarum affected more than 93% of the total Caribbean population. Although there are no records about the status of Diadema populations before and after die-off on Cuban reefs, anecdotal information suggests that populations were struck. We analyzed spatial variation in the abundance and size structure of D. antillarum in 22 reefs sites in Jardines de la Reina, from June 2004 to September 2005. Counts of Diadema were performed in five 30x2m transects at each sampling site and sampling time, and test diameters were measured in September 2005 at the same fore reefs. Abundances were higher at reef crests (mean densities 0.08-2.18 ind./m²), while reef slope populations reached a maximum site level of 0.13 ind./m² at only one site and showed values up to three orders of magnitude lower than those from reef crests. Highest abundance occurred at the west margin of major channels between keys where larval recruitment seems to be favored by local oceanographic features and facilitated by the abundance of Echinometra lucunter. The size frequency distribution of D. antillarum indicates that recruitment began to be noticeable three years before September 2005, suggesting these populations were depleted in the past and they are recovering now. Rev. Biol. Trop. 58 (2): 663-676. Epub 2010 June 02.

La mortalidad de Diadema antillarum en 1983-1984 afectó más del 93% de la población del Caribe. Aunque no existen datos publicados sobre el estado de sus poblaciones en arrecifes cubanos antes y después de la mortalidad, se conoce anecdóticamente que fueron afectadas. En el presente trabajo se analizan las variaciones espaciales de la abundancia y estructura de tallas de D. antillarum en 22 arrecifes frontales en Jardines de la Reina, para lo cual se realizaron cinco recorridos de 30x2m en cada sitio entre Junio de 2004 y Septiembre de 2005. Las densidades de Diadema fueron mayores en las crestas arrecifales (0.08-2.18 ind./m²) mientras que en las pendientes fueron hasta tres órdenes de magnitud menor y la densidad máxima fue 0.13 ind./m². Las crestas con mayor abundancia de Diadema están ubicadas en los márgenes de las grandes pasas existentes entre cayos donde el reclutamiento parece estar favorecido por las condiciones oceanográficas locales y facilitado por la abundancia de Echinometra lucunter. La distribución de frecuencia de tallas de Diadema sugiere que el reclutamiento comenzó a ser notable aproximadamente tres años antes del muestreo, indicando que en el pasado sus poblaciones estuvieron afectadas y ahora están recuperándose.

Variabilidad temporal de la abundancia de Coralliophila abbreviata y Coralliophila caribaea (Mollusca, Coralliophilidae) en un arrecife coralino del Parque Nacional Morrocoy, Venezuela

Temporary abundance variation of Coralliophila abbreviata and Coralliophila caribaea (Mollusca, Coralliophilidae) in a coral reef at Morrocoy National Park. The mollusks Coralliophila abbreviata and C. caribaea are coral predators in the Caribbean Sea . We evaluated the temporal variability of abundance and size structure of C. abbreviata and C. caribaea in Cayo Sombrero, Morrocoy National Park, Venezuelar (September 2004 - August 2005). The density of C. abbreviata and C. caribaea was evaluated monthly by means of two 50- meter long transects paralell to the coast line, at 3 m and 6 m deep; aditionally, 30 individuals of C. abbreviata were collected to measure size. The densities of C. abbreviata at the shallow transect fluctuated between 1.78 ind/m² in September and 6.26 ind/m² in May. The densities at the deep transect fluctuated between 4.23 ind/m² in January and 7.66 ind/m² in May. The densities of C. caribaea at the shallow transect fluctuated between 0 ind/m2 (except in September) and 0.03 ind/m² (September) and the densities at the deep transect fluctuated between 0 ind/m² (October to March and July) and 0.1 ind/m² (April). Most individuals of C. abbreviata and C. caribaea measured between 12 and 16 mm and between 10 and 15 mm long respectively. Rev. Biol. Trop. 56 (2): 501-511. Epub 2008 June 30.

C. abbreviata y C. caribaea son moluscos coralívoros del Mar Caribe. Evaluamos la variabilidad temporal de la abundancia y los cambios en la estructura de talla de C. abbreviata y C. caribaea en Cayo Sombrero, Venezuela (septiembre 2004-agosto 2005). Se colocaron transectas fijas de 50 metros de longitud a profundidades de tres y seis metros cada una, paralelas a la costa. Se evaluó mensualmente durante un año la densidad de ambos depredadores y se seleccionaron 30 individuos de C. abbreviata para medirlos cada mes. Las densidades de C. abbreviata en la transecta somera fluctuaron entre 1.78 ind/m² en septiembre y 6.26 ind/m² en mayo; las densidades de C. abbreviata en la transecta profunda estuvieron comprendidas entre 4.23 ind/m² en enero y 7.66 ind/m² en mayo. Las densidades de C. caribaea fluctuaron en la transecta somera entre 0 ind/m² (todos los meses menos septiembre) y 0.03 ind/m² (septiembre) mientras que la transecta profunda fluctuó entre 0 ind/m² (octubre a marzo y julio) y 0.1 ind/m² (abril). La mayoría de los individuos de C. abbreviata midieron entre 12 y 16 mm de longitud. El largo de la mayoría de los individuos de C. caribaea estuvo comprendido entre 10 y 15 mm.

Sex ratio and size structure of Micropogonias furnieri (Desmarest, 1823) (Perciformes, Sciaenidae) in Sepetiba Bay, Rio de Janeiro, Brazil

Sex ratio and size structure constitute basic information in assessing reproductive potential and estimating stock size in fish populations. One hundred fifty-one individuals of Micropogonias furnieri caught by experimental otter trawls, in three zones (inner, central, and outer) of Sepetiba Bay between October 1998 and September 1999 were examined. Males outnumbered females (1.3:1.0) in all zones but no significant differences were detected. Only in the outer zone (5.0:1.0) were male/female rates significantly different according to the chi-square test. No temporal differences were observed in sex ratio. Fish size ranged from 81 to 244 mm total length (TL) with significant differences in 155 to 185 mm TL size classes, where males predominated, and a slightly higher number of females were observed for the smaller size class (TL = 95-150 mm). Size distribution varied according to the zone, with juveniles predominating in the inner and adults in the outer zone. Spatial difference in size structure observed in this study indicates that the inner bay is a rearing ground during the first life-cycle period, and movement toward the sea occurs as fish increase in size.

RESUMO A proporção sexual e a estrutura de tamanho são informações básicas para avaliação do potencial reprodutivo e para estimativa do tamanho do estoque das populações de peixes. Foram utilizados 151 indivíduos de Micropogonias furnieri, capturados em arrastos de fundo padronizados, nas zonas interna, central e externa da Baía de Sepetiba, entre outubro de 1998 e setembro de 1999. A proporção entre machos e fêmeas para toda a Baía foi de 1,3:1,0, não apresentando diferença significativa. Somente a zona externa (5,0:1,0) apresentou maior número de machos que o de fêmeas de acordo com o teste c². Não se observou um padrão temporal de diferenciação na proporção sexual ao longo do ano. A população variou de 81 a 244 mm de comprimento total (CT) com diferença significativa entre os sexos apenas entre 155 e 185 mm de CT onde os machos predominaram. Observou-se gradativo aumento do tamanho dos peixes da zona interna para a externa. A diferenciação da estrutura de tamanho apresentada indica o uso da zona mais interna da baía como área de criação das corvinas nas primeiras fases de vida e um padrão de deslocamento para fora da baía à medida que estes peixes vão crescendo.