Efecto de la temperatura sobre la morfología y reproducción en el erizo de mar Arbacia dufresnii (Echinodermata: Echinoidea) / Effect of temperature on morphology and reproduction of sea urchin, Arbacia dufresnii (Echinodermata: Echinoidea)

Introducción: El aumento de los valores del CO2 atmosférico y el consecuente calentamiento del agua de mar constituyen factores de estrés para los ecosistemas marinos, renovando el interés en la fisiología de los equinoideos. El equinoideo Arbacia dufresnii es una especie ampliamente estudiada y con amplia distribución en los golfos norpatagónicos. Objetivo: Evaluar el efecto de temperatura del agua de mar sobre su morfología y reproducción. Métodos: Individuos de A. dufresnii fueron expuestos durante 10 semanas (Abril-Junio 2016) a tres tratamientos de temperatura (13 °C control, 15 °C y 17 °C) de acuerdo con las condiciones actuales del agua de mar y los valores esperados para el próximo siglo, según diferentes escenarios estimados. Al finalizar el experimento, diámetro y peso del individuo así como los pesos de los órganos internos fueron estadística e histológicamente analizados. Resultados: Se observó una mayor mortalidad en los individuos expuestos a las mayores temperaturas lo que podría deberse a un estrés en el individuo. Para el tratamiento control y el de 17 °C no se observaron cambios en los pesos secos de gónadas e intestino. En cambio, los individuos expuestos a 15 °C presentaron un aumento en el diámetro del caparazón y en el peso seco de gónadas e intestino. Los estadios gonadales aesta temperatura (15 °C) para machos fueron similares al ambiente a diferencia de las hembras que se observaron estadios más avanzados. Conclusiones: Esto indicaría que 15 °C podría ser la temperatura óptima para la asimilación del alimento y obtención de energía. A esta temperatura se observan cambios a corto plazo en los órganos de metabolismo rápido pero no en los órganos calcificados (caparazón y linterna de Aristóteles).

Introduction: The increase in atmospheric CO2 values and the consequent warming of seawater constitute stressors for marine ecosystems, renovating interest in echinoid physiology. The echinoid Arbacia dufresnii is a widely studied species with a wide distribution in the North Patagonian gulfs. Objective: Evaluate the effect of seawater temperature on its morphology and reproduction. Methods: Individuals were exposed for 10 weeks (April-June 2016) to three temperature treatments (13 °C control, 15 °C and 17 °C) according to the current conditions of seawater and the expected values for the next century. At the end of the experiment, diameter and weight of the whole individual and of its internal organs were statistically and histologically analyzed. Results: Individuals exposed to higher temperatures died in greater numbers. The control, and the 17 °C treatment, had no changes in dry gonad and intestine weights. However, the 15 °C group had wider diameter of test and a higher dry weight of gonads and intestine. At this temperature, the gonadal stages for males were similar to the environment, but females had more advanced stages. Conclusions: Temperature of 15°C could be optimal for assimilating food and obtaining energy. Gonads and intestine would be showing changes in the short term, unlike the calcified organs (test and Aristotle's lantern).

Morphological plasticity in the Aristotle's lantern of Arbacia dufresnii (Phymosomatoida: Arbaciidae) off the Patagonian coast / Plásticidad morfológica en la linterna de Aristoteles en Arbacia dufresnii (Phymosomatoida: Arbaciidae) en la costa Patagónica

Abstract The relative size of the Aristotle's lantern of most sea urchins varies in relation to the food availability and it is often used to infer the availability of food of the environment. The aim of our study was to evaluate the lantern morphology plasticity of Arbacia dufresnii in populations with different environmental characteristics, either mussel beds or disturbed areas, by the invasive alga Undaria pinnatifida along the Patagonian Atlantic coast. The test diameter of the sea urchins along with the weight and height of the lanterns, the jaw lenght and rotula lenght were measured. Classic and geometric morphometric analyses were performed to test differences among populations. The length of the jaw was the best indicator of relative changes in size of the lantern. The largest length of the jaw was measured in individuals from disturbed areas dominated by the invasive algae U. pinnatifida. The rotula shape changed with the increase of the diameter of the sea urchins, it tends to be more elongated with larger sea urchins. Rev. Biol. Trop. 63 (Suppl. 2): 339-351. Epub 2015 June 01.

Resumen El tamaño relativo de la linterna de Aristóteles en la mayoría de las especies de erizos de mar varía en relación con la disponibilidad de alimentos y se utiliza a menudo para inferir la disponibilidad de alimentos en el medio ambiente en que los erizos de mar habitan. El objetivo de este estudio fue evaluar la plasticidad morfológica de la linterna de Aristóteles de Arbacia dufresnii en poblaciones con diferentes características ambientales, ya sean con bancos de mejillones o áreas modificadas por el alga invasora Undaria pinnatífida, a largo de la costa patagónica atlántica. Se midió el diámetro del caparazón, el peso y el alto de las linternas, la longitud de la semipirámide y la longitud de la rótula. Los datos se analizaron utilizando técnicas de morfometría clásica y geométrica con el objetivo de probar diferencias entre las poblaciones. La longitud de la semipirámide fue el mejor indicador para describir los cambios relativos en el tamaño de la linterna. La mayor longitud de la semipirámide se observó en las poblaciones que habitan áreas dominadas por el alga invasora U. pinnatifida. La forma de la semipirámide no varía entre las poblaciones ni con el tamaño de los erizos de mar, mientras que la forma de la rótula cambia en relación al tamaño de los erizos, siendo más alargada cuando el tamaño de los individuos es mayor.

Ciclo gametogénico del erizo marino Echinometra lucunter (Echinometra: Echinoidea) en el Noriente de Venezuela / Gametogenic cycle of the rock boring urchin Echinometra lucunter (Echinodermata: Echinoidea) in northeastern Venezuela

Resumen El ciclo gametogénico y el índice gonadosomático (IG) del erizo negro Echinometra lucunter fue examinado entre junio de 2010 y noviembre de 2011 en el noreste de Venezuela (Isla de Lobos, Península de Araya y Ensenada de Turpialito, Golfo de Cariaco). Las gónadas están integradas por extensos acinos ramificados, recubiertos por tejido conectivo, seguido de una capa delgada de células que se diferencian en fagocitos nutritivos y gametos, los cuales cambian en sus proporciones y tamaños con los estadios de maduración. Generalmente, en ambas localidades se presentaron varios estadios de maduración, con desoves simultáneos. En Isla Lobos predominaron los individuos en estado de reserva con un corto período de madurez sexual, mientras que en la Ensenada de Turpialito predominaron organismos maduros y desovados. El IG sugiere que los desoves están asociados a las precipitaciones estacionales de la región; mostrando una estrategia reproductiva conservadora, acumulando reservas energéticas en el periodo de mayor producción primaria asociada a los periodos de surgencia costera, cuando la energía de los fagocitos nutritivos es transferida a los gametos hasta su maduración y expulsión al medio ambiente. Las características biológicas y reproductivas de los organismos en Turpialito mostraron elevados IG y mayor tejido gonadal para consumo comercial.

Abstract Several species of sea urchins are a potential resource for the production of gonads for consumption in Venezuela. We studied the gametogenic cycle and the gonadosomatic index (GSI) of the rock boring urchin Echinometra lucunter between June 2010 and November 2011 in northeastern Venezuela (Isla Lobos, Península de Araya and Turpialito, Gulf of Cariaco). The gonads are composed of long ramified acini, covered by connective tissue, followed by a thin layer of cells that differentiate into nutritive phagocytes and gametes, which change in their proportion and size with the maturity stage. Generally, several maturity stages were observed in both locations, showing simultaneous spawning. At Isla de Lobos the individuals in reserve stage predominated with a short period of sexual maturity, while mature and spawned individuals predominated in Turpialito. The GSI suggests that the greatest spawning activity is associated to the rainy season; showing a conservative reproductive activity, accruing energetic reserves during the period of higher primary productivity associated to coastal upwelling, when the energy of nutritive phagocytes is transferred to gametes, for gamete development and spawning. The biological and reproductive characteristics of individuals at Turpialito showed higher GSI having more gonadal tissue for commercial consumption. Rev. Biol. Trop. 63 (Suppl. 2): 273-283. Epub 2015 June 01.

Densidad poblacional, distribución espacial y mortalidad natural del erizo de mar Toxopneustes roseus (Camarodonta: Toxopneustidae) en tres sitios de Oaxaca, México / Population density, spatial distribution and natural mortality of the sea urchin Toxopneustes roseus (Camarodonta: Toxopneustidae) at three sites in Oaxaca, Mexico

Resumen En el presente estudio se evaluó la densidad poblacional, patrón de distribución espacial y mortalidad natural del erizo de mar Toxopneustes roseus, así como la relación entre la densidad poblacional y algunas variables ambientales. De octubre 2009 a septiembre 2011 se realizaron muestreos mensuales utilizando transectos de banda en tres localidades de la costa de Oaxaca, México: Estacahuite, Dos Hermanas e Isla Cacaluta. Adicionalmente se registró in situ la temperatura, salinidad y pH en cada localidad. Los registros de irradiación y precipitación pluvial se obtuvieron de bases de datos. El patrón de distribución se caracterizó mediante el Índice de Morisita, los modelos de probabilidad de Poisson y Distribución Binomial Negativa. La mortalidad natural se estimó utilizando el método modificado de Berry. Se aplicó un análisis de regresión lineal múltiple paso a paso para evaluar la relación entre la densidad poblacional y las variables ambientales. La densidad promedio (± DE) fue 0.12 ± 0.02 ind m-2 (Estacahuite), 0.05 ± 0.01 ind m-2 (Dos Hermanas) y 0.04 ± 0.01 ind m-2 (Isla Cacaluta). El patrón de distribución espacial fue agregado en la mayoría de los meses muestreados en las tres localidades. En Estacahuite la mortalidad natural fue 0.54 y en Dos Hermanas 0.46, para Isla Cacaluta no fue posible calcular la mortalidad natural. De las variables ambientales registradas, la precipitación pluvial mostró una relación directa pero no determinante con la densidad poblacional de T. roseus en Isla Cacaluta. Se concluye que los factores que podrían determinar la dinámica poblacional de T. roseus son: áreas con mayor extensión en general y el aporte de sedimentos por la presencia de ríos en las localidades, ya que Isla Cacaluta fue la única localidad en la que se evidenció una relación importante con la precipitación pluvial y esta localidad se ve influenciada por los ríos Copalita y Coyula, los cuales producen un importante incremento en la tasa de sedimentación en esta localidad, afectando a la comunidad bentónica en general durante la temporada de lluvias.

Abstract The sea urchin Toxopneustes roseus is widely distributed along the east coast of the tropical Pacific, from Mexico to northern Peru. In our study we evaluated population features of this species, such as population density, spatial distribution pattern and natural mortality, as well as the relationship between population density and several environmental variables. From October 2009 to September 2011 monthly sampling was carried out using belt transects in three localities of the coast of Oaxaca, Mexico: Estacahuite, Dos Hermanas and Isla Cacaluta. Additionally we recorded in situ temperature, salinity and pH in each locality. Records of irradiation and pluvial precipitation were obtained from databases. Distribution pattern of the urchins was characterized using the Morisita´s Index and the models of Poisson´s probability and Negative Binomial Distribution. Natural mortality was estimated using the modified method of Berry. A step by step analysis of Multiple Lineal Regression was applied to evaluate the relationship between population density and the recorded environmental variables. Mean (± SD) density was 0.12 ± 0.02 ind·m-2 (Estacahuite), 0.05 ± 0.01 ind·m-2 (Dos Hermanas) and 0.04 ± 0.01 ind·m-2 (Isla Cacaluta). The pattern of spatial distribution of T. roseus was aggregated in most of the sampled months in all the localities. In Estacahuite natural mortality was 0.45 and in Dos Hermanas it was 0.46, it was not possible to calculate mortality for Isla Cacaluta. Of the recorded environmental variables, pluvial precipitation showed a direct but not determinant relationship with population density of T. roseus only in Isla Cacaluta. As a result of the differences observed in the three localities we assume that the factors that could determine the population dynamics of T. roseus are: A larger extension of the area in general, and the contribution of sediments by the presence of rivers in the localities, since Isla Cacaluta was the only locality where there was evidence of an important relationship with pluvial precipitation, and this locality undergoes the influence of the rivers Copalita and Coyula, which produce an important increase in sedimentation rates at this community, affecting the entire benthic community during the rainy season. Rev. Biol. Trop. 63 (Suppl. 2): 121-133. Epub 2015 June 01.

Taxonomía y biogeografía ecológica de los equinoideos irregulares (Echinoidea: Irregularia) de México / Taxonomy and ecologic biogeography of the irregular Echinoids (Echinoidea: Irregularia) from Mexico

Resumen La localización geográfica de México, entre las influencias oceánicas del Atlántico centro-occidental y del Pacífico centro-oriental, explica en gran medida su enorme diversidad biológica y ecosistémica. Las investigaciones sobre equinodermos en México comenzaron a mitades del siglo XIX, si bien aún no existe un trabajo sobre los equinoideos irregulares que habitan sus aguas. En este trabajo se presenta por primera vez una revisión taxonómica de los equinoideos irregulares de México. En este sentido, se usaron los ejemplares de equinoideos irregulares para México albergados en cuatro colecciones: 1) Colección Nacional de Equinodermos "Ma. Elena Caso Muñoz", del Instituto de Ciencias del Mar y Limnología (ICML), Universidad Nacional Autónoma de México (UNAM); 2) Invertebrate Zoology Collection, Smithsonian Museum of Natural History, Washington, D.C., United States of America (USA); 3) Invertebrate Collection, Museum of Comparative Zoology, University of Harvard, Boston, Massachusetts, USA and 4) Invertebrate Zoology, Peabody Museum, Yale University, New Haven, Connecticut, USA. Los organismos fueron reidentificados, se corroboró la identidad taxonómica de las especies y se ubicaron taxonómicamente. Además, se realizó un análisis de biogeografía ecológica tomando en cuenta el listado de especies obtenido y la regionalización ecológica de Norteamérica. Se presenta un total de 69 especies incluidas en 6 órdenes, 17 familias, y 36 géneros distribuidas en 34 ecorregiones biogeográficas; 11 de la costa Atlántica y 23 de la costa Pacífica. Se delimitan cuatro regiones biogeográficas Atlánticas y cinco Pacíficas. En la costa Atlántica, los factores ambientales que determinan la distribución de los equinoideos irregulares son, principalmente los sedimentos y las corrientes oceánicas, mientras que en la costa Pacífica son principalmente la profundidad y las corrientes oceánicas.

Abstract Mexico owns 643 species of echinoderms, almost 10% of the known echinoderm species in the planet. Its geographic location -between the oceanic influences of the Western Central Atlantic and the Eastern Central Pacific- largely explains its enormous biological and ecological diversity. Research on echinoderms in Mexico began in the late nineteenth century; however, there are no reviews on its irregular echinoids. This work reviews the taxonomic and geographic information of irregular echinoids from Mexico, housed in four collections: 1) Colección Nacional de Equinodermos "Ma. Elena Caso Muñoz" from the Instituto de Ciencias del Mar y Limnología (ICML), Universidad Nacional Autónoma de México (UNAM); 2) Invertebrate Zoology Collection, Smithsonian Museum of Natural History, Washington, D.C., United States of America (USA); 3) Invertebrate Collection, Museum of Comparative Zoology, University of Harvard, Boston, Massachusetts, USA and 4) Invertebrate Zoology, Peabody Museum, Yale University, New Haven, Connecticut, USA. Specimens were reidentified and classified; geographic distribution data were subjected to a parsimony analysis of endemisms (PAE) using the ecological regionalization of North America proposed by Wilkinson et al. (2010). A total of six orders, 17 families, 35 genera and 68 species are reported, distributed in 34 ecoregions, 11 from the Atlantic coast and 23 from the Pacific coast. Nine biogeographic regions were delimited, four in the Atlantic coast and five in the Pacific coast. The biogeographic analysis suggests that the oceanic currents and sediments are the environmental factors that determine the distribution of irregular echinoids in the Mexican Atlantic coast; on the other hand, oceanic currents and depth are the environmental factors that determine the distribution of irregular echinoids in the Mexican Pacific coast. Rev. Biol. Trop. 63 (Suppl. 2): 59-75. Epub 2015 June 01.

Micro identificación taxonómica y nuevos caracteres diagnósticos del erizo marino Astropyga pulvinata (Diadematoida: Diadematidae) / Taxonomic microidentification and new diagnostic characters of the sea urchin Astropyga pulvinata (Diadematoida: Diadematidae)

Resumen Astropyga pulvinata es un diademátido que posee cinco pares de series de puntos iridiscentes presentes en los interambulacros. A partir de la observación 20 individuos in vivo a través de un estereoscopio y el análisis con un Microscopio Electrónico de Barrido se identificaron los pedicelarios, las espículas y las rosetas calcáreas de los pies ambulacrales. Los pedicelarios presentes en A. pulvinata son trivalvados y de tres tipos: claviformes (oficéfalos) presentes en ambulacro; tridentados distribuidos en el peristoma; y trifoliados presentes en toda la testa excepto en los interambulacros. Los pedicelarios claviformes son los únicos que no están unidos por un pedúnculo calcáreo de tipo diadematoide. Se obtuvieron diez tipos de espículas de diversos tejidos blandos: uno del intestino; tres de la membrana anal y seis del peristoma, dos de las cuales no han sido descritas hasta el momento. Uno de estos nuevos tipos de espículas reportados posee forma de basto y otro de media luna. De las observaciones in vivo se encontraron puntos iridiscentes más pequeños presentes en el ambitus constituidos por aproximadamente ocho células.

Abstract Astropyga pulvinata is a sea urchin of the family Diadematidae that have five pairs of series of blue iridescent spots on interambulacral zones, from in vivo observation of 20 individuals under stereo-microscope and Scanning Electron Microscope analysis identification, the pedicellariae, spicules, and calcareous rosettes. The pedicellariae of A. pulvinata have three valves and are of three types: claviform, present on ambulacres; tridentates present on peristome and triphyllous present all over the test except in interambulacral areas. So ophicephalous pedicellariae are not bounded with a calcareous stalk. Ten types of spicules were observed from different soft tissues: one type from the intestine; three from the anal membrane; and six from the peristome, two of them constitute new diagnostic characters. One of them having a bat-shaped form and the other one with a waning crescent shape. In vivo observations showed that the blue iridescent spots were present on interambulacral areas as group of 35 cells bounded, and that other smaller spots were present on the ambitus, composed by eight cells. Rev. Biol. Trop. 63 (Suppl. 2): 49-58. Epub 2015 June 01.

Diadema ascensionisMortensen, 1909 (Echinodermata: Echinoidea) is not restricted to Oceanic Islands: evidence from morphological data / Diadema ascensionisMortensen, 1909 (Echinodermata: Echinoidea) não está restrito a Ilhas Oceânicas: evidências de dados morfológicos

The genus Diadema presently consists of seven species, two of which are known from the Brazilian coast: D. antillarum and D. ascensionis. The first is usually known for shallow coastal areas, while the second was apparently restricted to oceanic islands. In February 2011, a dense population of D. ascensionis was observed on the coastal reefs of Praia do Francês (Alagoas State, northeastern Brazil). Five specimens were collected and transported to the laboratory where morphological studies of the test and pedicellariae were conducted. Subsequently, visits were made to scientific collections in order to compare and confirm species identifications. Our observations confirm the presence of tridentate pedicellariae with narrow and strongly curved valves. The axial cavity in the tips of the spines is filled with dense nonreticular tissue. This taxonomic data confirms the occurrence of D. ascensionis in coastal areas. On the coastal reefs of Praia do Francês, animals were observed from the beach to the reef formations about 200 m offshore in areas with a sandy substrate and in reef cavities, usually in clear and well illuminated waters. Solitary individuals or groups of up to 15 individuals formed dense populations in the area. We stress the importance of pedicellariae for the specific identification of the Diadematidae, considering that they are quite constant and reliable at this taxonomic level. Our results demonstrate that D. ascensionis is not restricted to insular environments and that this species may be common in shallow coastal habitats.

O gênero Diadema é composto por sete espécies, das quais duas são conhecidas para o litoral brasileiro: D. antillarum e D. ascensionis. A primeira é principalmente conhecida em áreas costeiras, enquanto que a segunda está aparentemente restrita a ilhas oceânicas. Em fevereiro de 2011, uma densa população de D. ascensionis foi observada nos recifes costeiros da Praia do Francês, no Estado de Alagoas, Região Nordeste do Brasil. Cinco espécimes foram coletados e transportados ao laboratório, onde estudos morfológicos da carapaça e das pedicelárias foram desenvolvidos. Subsequentemente, foram realizadas visitas a coleções científicas para a comparação e a confirmação da espécie. As observações, neste trabalho, evidenciaram a presença de uma pedicelária tridentada com valvas estreitas e fortemente curvadas. A cavidade axial nas pontas dos espinhos é preenchida por um denso tecido não reticular. Estes dados taxonômicos confirmam a ocorrência de D. ascensionis em áreas costeiras. Nos recifes costeiros da Praia do Francês, os animais foram observados a partir da praia em direção às formações recifais localizadas a 200 m da praia, em áreas de substrato arenoso, e nas cavidades do recife, geralmente em águas claras e bem iluminadas. Os indivíduos estavam solitários ou formando grupos de até 15 indivíduos. Destaca-se a importância das pedicelárias na sistemática dos Diadematidae, tendo em vista que as mesmas são bastante constantes e confiáveis para a identificação em nível específico. Os resultados do presente trabalho demonstram que D. ascensionis não está restrita a ambientes insulares e que esta espécie pode ser comum em habitats costeiros rasos.

Diadema ascensionis / Diadema ascensionis

The genus Diadema presently consists of seven species, two of which are known from the Brazilian coast: D. antillarum and D. ascensionis. The first is usually known for shallow coastal areas, while the second was apparently restricted to oceanic islands. In February 2011, a dense population of D. ascensionis was observed on the coastal reefs of Praia do Francês (Alagoas State, northeastern Brazil). Five specimens were collected and transported to the laboratory where morphological studies of the test and pedicellariae were conducted. Subsequently, visits were made to scientific collections in order to compare and confirm species identifications. Our observations confirm the presence of tridentate pedicellariae with narrow and strongly curved valves. The axial cavity in the tips of the spines is filled with dense nonreticular tissue. This taxonomic data confirms the occurrence of D. ascensionis in coastal areas. On the coastal reefs of Praia do Francês, animals were observed from the beach to the reef formations about 200 m offshore in areas with a sandy substrate and in reef cavities, usually in clear and well illuminated waters. Solitary individuals or groups of up to 15 individuals formed dense populations in the area. We stress the importance of pedicellariae for the specific identification of the Diadematidae, considering that they are quite constant and reliable at this taxonomic level. Our results demonstrate that D. ascensionis is not restricted to insular environments and that this species may be common in shallow coastal habitats.

O gênero Diadema é composto por sete espécies, das quais duas são conhecidas para o litoral brasileiro: D. antillarum e D. ascensionis. A primeira é principalmente conhecida em áreas costeiras, enquanto que a segunda está aparentemente restrita a ilhas oceânicas. Em fevereiro de 2011, uma densa população de D. ascensionis foi observada nos recifes costeiros da Praia do Francês, no Estado de Alagoas, Região Nordeste do Brasil. Cinco espécimes foram coletados e transportados ao laboratório, onde estudos morfológicos da carapaça e das pedicelárias foram desenvolvidos. Subsequentemente, foram realizadas visitas a coleções científicas para a comparação e a confirmação da espécie. As observações, neste trabalho, evidenciaram a presença de uma pedicelária tridentada com valvas estreitas e fortemente curvadas. A cavidade axial nas pontas dos espinhos é preenchida por um denso tecido não reticular. Estes dados taxonômicos confirmam a ocorrência de D. ascensionis em áreas costeiras. Nos recifes costeiros da Praia do Francês, os animais foram observados a partir da praia em direção às formações recifais localizadas a 200 m da praia, em áreas de substrato arenoso, e nas cavidades do recife, geralmente em águas claras e bem iluminadas. Os indivíduos estavam solitários ou formando grupos de até 15 indivíduos. Destaca-se a importância das pedicelárias na sistemática dos Diadematidae, tendo em vista que as mesmas são bastante constantes e confiáveis para a identificação em nível específico. Os resultados do presente trabalho demonstram que D. ascensionis não está restrita a ambientes insulares e que esta espécie pode ser comum em habitats costeiros rasos.

A recent increase in the abundance of the echinoid Diadema antillarum in Dominica (Lesser Antilles): 2001-2005 / Un aumento reciente en la abundancia del equinoideo Diadema antillarum en Dominica (Antillas Menores): 2001-2005

Diadema antillarum populations at many Caribbean locations have failed to recover from the pathogen-induced mortality events of the 1980s. It has become clear that the massive decline of this herbivorous urchin and the wide-spread absence of a population recovery lead to numerous long-term ecological consequences and reef degradation. While few quantitative studies on pre-mortality exist, great effort has been put forth to monitor remaining populations and their recovery. However, the patchy distribution of D. antillarum coupled with paucity of long-term studies based on the same methods applied at the same locations undermines the value of local as well as regional comparisons. In Dominica, ongoing quantitative assessments of D. antillarum began in 2001. Surveys of D. antillarum abundance are being carried out in 4-month intervals at six 100 m² sites; spread over 38 km along the west coast. The density of D. antillarum has differed significantly between sites, ranging from 0.81(SD= 0.04) to 3.13 m-2 (SD= 2.10), and increased by 61.11% during the first five years of this study. Seasonal fluctuations, possibly related to spawning aggregations, are also evident. The current abundance of D. antillarum on Dominican reefs contrasts that of Caribbean locations with recorded incidents of mass mortality events, and in some cases resembles pre-mortality densities from the early 1970s. Prior to this study, no systematic quantitative assessments of D. antillarum were carried out in Dominica. It is thus unclear in what way Dominica’s D. antillarum were affected by the mass mortality events observed elsewhere in the 1980s. The increase in D. antillarum density so far observed may thus be the recovery from a pathogen-induced disturbance or from Hurricane Lenny in November 1999. Locally, D. antillarum is important grazer on Dominican’s reefs, where over-fishing has drastically reduced the number of herbivorous fishes. On a regional scale, the island’s D. antillarum may represent a source of larvae for downstream islands, given the duration of the echinoplutei stage and a range of larval dispersal of hundreds of kilometers. Rev. Biol. Trop. 54 (Suppl. 3): 97-103. Epub 2007 Jan. 15.

Las poblaciones de Diadema antillarum de muchas localidades del Caribe, no se han recuperado después de los eventos de mortandad, inducidos por un patógeno, en la década de 1980. Se ha podido demostrar que la muerte masiva de este erizo herbívoro y la ausencia de recuperación, han tenido consecuencias ecológicas que han producido la degradación de los arrecifes. Existen pocos estudios pre-mortalidad, pero se han realizado grandes esfuerzos para monitorear las poblaciones restantes y su recuperación. Sin embargo, la distribución en parches de D. antillarum combinado con pocos estudios a largo plazo usando la misma metodología en los mismos sitios, mina la posibilidad de comparaciones locales y regionales. En Dominica, el monitoreo cuantitativo de D. antillarum empezó en 2001. Cada cuatro meses se realizan determinaciones de abundancia de D. antillarum en seis sitios de 100 m²; distribuidos a lo largo de 38 km de la costa oeste. La densidad de D. antillarum, fue significativamente diferente entre sitios, con ámbitos de 0.81 (SD= 0.04) a 3.13 m-2 (SD= 2.10), y aumentó 61.11% durante los primeros cinco años de estudio. Fluctuaciones estacionales, posiblemente relacionadas con agregaciones reproductivas, son evidentes. La abundancia actual de D. antillarum en los arrecifes de Dominica contrasta con otros sitios en el Caribe que sufrieron mortandades masivas y en algunos casos se parece a densidades pre-mortalidad de inicios de la década de 1970. Antes de este trabajo, no se había realizado ningún estudio sistemático de Diadema en Dominica, por lo que no es claro como fueron afectadas las poblaciones en este sitio. El aumento en la densidad de D. antillarum observado hasta ahora puede deberse a recuperación tras una perturbación por un patógeno o por el Huracán Lenny de noviembre 1999. Localmente, D. antillarum es un herbívoro importante en los arrecifes de Dominica donde la sobrepesca ha disminuido el número de peces herbívoros. En escala regional, las poblaciones de D. antillarum de la isla de Dominica pueden representar una fuente de larvas corriente abajo, dada la duración de estadio equiinopluteo y el ámbito de dispersión de las larvas, que es de cientos de kilómetros.

Demografía y pesquería del erizo Loxechinus albus (Echinodermata: Echinidae) en la región sur-austral de Chile / Demography and fishery of the sea urchin Loxechinus albus (Echinodermata: Echinidae) in south-austral Chile region

In the Magellan Region of southern Chile (52 degrees 20'S - 55 degrees 30'S), the edible urchin Loxechinus albus is collected by 1200 artisanal fishermen, of whom 450 are divers. About 360 small fishing boats and 54 transport vessels carry the fresh product to 16 processing plants. Landings of about 27 000 tons were recorded between January and December 1995. Test diameters of urchins harvested monthly were measured for a total of 119 239 specimens, and 36 406 specimens were individually weighed; sex determination was carried out on 2 314 specimens. Field data indicate that the harvest was about 6.6 x 106 dozen urchins (this is a measuring method employed by fishermen in the region), with an extractive effort of 14 753 diver/days. The fisheries yield ranged from an annual minimum of 235 DUDD (dozen urchins per diver/day) to a maximum of 660 DUDD. In overall terms, the lowest average yields were between January and April (415-427 DUDD), and the highest yields between May and December (456-510 DUDD). Mean sizes increased from June to November and decreased from December to June. Size frequency of males and females were polymodal, with the most relevant modes at 72-84 mm in males, and at 79-88 mm in the females. The percentage of individuals below the minimum legal size (70 mm) did not exceed 4.9% for males and 3.6% for females. The size-weight records fit a power model which suggested that this species has a negative allometric growth (b = 2.007). Regarding weight, urchins in the size range from 80.0 to 84.9 mm were those with the maximum contribution to the regional landings. The highest values recorded for the utilized condition factor were: Average Condition Factor (ACF) = May to July, and November; Isometric (or Cubic) Condition Factor (ICF) = July; and Allometric Condition Factor (ACF) = June. Spawning occurred mainly between August and September, and ended by the end of October. Exploitation of this species represents one of the main sources of employment for the artisanal fisheries sector in the Magellan Region. The main difficulty observed in this fishery was obtaining a sufficient supply of urchins with a yellow-gold colored gonadic material, which forms the basis for demand of this urchin by the international market.