Estructura de la comunidad y distribución vertical de la macrofauna de fondos blandos en isla Gorgona, Pacífico Colombiano / Community structure and vertical distribution of the soft bottom macrofauna on Isla Gorgona, Colombian Pacific

Soft bottoms are important in marine ecosystems but their ecology have been less studied in the tropics than in temperate areas. This article describes the temporal, spatial, and vertical distribution of the community structure of subtidal soft bottom macrofauna on Isla Gorgona, Colombian Pacific. Samples were collected in March and June 2011 by corers at 10m depth at five points around the island. Seventy-three species were recorded; polychaetes (55%) and crustaceans (30%) were the dominant groups in number of individuals. The community structure assessed by classification and ordination analysis did not change temporarily, but it shows differences between sampling points, due to the structure of the substrate. The highest abundances of macrofauna were recorded at points with dominance of fine particles (Farallones). However, another point with a similar substrate (Planchón) showed low abundance, apparently due to bioturbation exerted by the fish Heteroconger sp. The presence of Heteroconger sp. in El Planchón could also affect the vertical distribution of the macrofauna, where their relative abundance was homogeneous across the analyzed layers (1-2-3-4-5-10cm). In the other four sites, the abundance of the macrofauna was mainly limited to the first two centimeters of the sediment. Playa Blanca and Remanso showed substrates composed mainly of gravel, recording at the last sampling point the lowest richness, diversity and abundance. Rev. Biol. Trop. 62 (Suppl. 1): 169-188. Epub 2014 February 01.

Resumen Se evaluó la variación temporal, espacial y vertical de la estructura comunitaria de la macrofauna de fondos blandos submareales en isla Gorgona, Pacífico colombiano. Las muestras fueron colectadas en marzo y junio de 2011 mediante descorazonadores a 10m de profundidad en cinco puntos alrededor de la isla. Se registraron un total de 73 especies; poliquetos (55%) y crustáceos (30%) fueron los grupos dominantes en número de individuos. La estructura comunitaria evaluada mediante análisis de clasificación y ordenación, no varió temporalmente, pero si presentó diferencias entre puntos de muestreo, al parecer relacionada con la estructura del sedimento. Las mayores abundancias de la macrofauna se registraron en puntos con dominancia de partículas finas (Farallones), pero en otro punto con sustrato similar (Planchón), la abundancia fue baja, al parecer por la bioperturbación ejercida por el pez Heteroconger sp. La presencia de Heteroconger sp. en el Planchón posiblemente afectó la distribución vertical de la macrofauna, ya que en este último punto la abundancia relativa fue homogénea entre las capas analizadas (1-2-3-4-5-10cm). En los otros cuatro sitios, la abundancia de la macrofauna estuvo limitada principalmente a los primeros dos centímetros del sedimento. En Playa Blanca y Remanso el sustrato fue principalmente gravoso, registrándose en el último punto la menor riqueza, diversidad y abundancia.

Regional diversity of Amphipoda in the Caribbean Sea / Diversidad regional de Amphipoda en el Mar Caribe

The order Amphipoda is one of the most diverse within Peracarids, and comprises 6 950 described marine species. Amphipod research in the Caribbean Sea began in the late 1 800s, but has increased significantly since 1 980. In this study, we analized the amphipod biodiversity (Caprellidea, Gammaridea, Hyperiidea, and Ingolfiellidea) of the Caribbean Sea. For this, we compiled available data on species diversity of marine amphipods (data bases: WoRMS and OBIS and published species lists) into a comprehensive taxonomic list by country for the ecoregions of the Caribbean. Additionally, we analized the relative contribution of each country to regional diversity and the rate of discovery of new species. The Caribbean amphipod fauna is composed of 535 species within 236 genera and 73 families for the higher taxon. The Western Caribbean ecoregion holds the largest diversity (282 species), while the Eastern Caribbean recorded the lowest one (73). Mexico and Venezuela recorded the largest number of species with 266 and 206, respectively. Twelve countries had less than 50 species. The richest suborder is the Gammaridea with 381 species followed by the suborder Hyperiidea with 116. From the total of 535 amphipod species reported for the Caribbean region, 218 have the Caribbean as the holotype locality, and 132 are endemic (about 25% of the total). Areas of higher diversity seem to be concentrated along the Mexican Caribbean, Cuba and the Northern coast of South America (Venezuela-Colombia); however, such pattern is most likely reflecting local collection efforts and taxonomic expertise rather than actual distribution. Knowledge of amphipod species is mostly limited to shallow, near-shore waters, with little information available on the deep sea fauna. Regional research priorities for this group should be focused on completing shallow water coastal inventories of species in Central America and the Greater and Lesser Antilles. In addition, sampling the deep sea ecosystems should follow along with other particular habitats such as anchialine cave systems. It is also neccessary to increase ecological research efforts, mainly in some speciose suborders, including the Caprellidea and Hyperiidea, known to exhibit high diversity in other tropical localities. Rev. Biol. Trop. 61 (4): 1681-1720. Epub 2013 December 01.

El orden Amphipoda es uno de los más diversos dentro de los Peracáridos. Las investigaciones sobre este orden en el Mar Caribe se iniciaron a finales de los años 1800, incrementándose significativamente a partir de 1980. En este estudio se analizó la biodiversidad de los anfípodos (Caprellidea, Gammaridea, Hyperiidea e Ingolfiellidea) en el Mar Caribe, compilándose los registros de especies citadas en las diversas ecorregiones del área, tanto en publicaciones como a través de bases de datos (WoRMS y OBIS). Se listan un total de 535 especies pertenecientes a 236 géneros y 73 familias. La ecorregión del Caribe Occidental presentó la mayor riqueza específica (282), mientras que el Caribe Oriental presentó el menor valor (73). México y Venezuela presentaron el mayor número de especies registradas (266 y 206, respectivamente), mientras que doce países presentaron menos de 50. Los Gammaridea fueron el grupo más diverso con 387 especies, seguido de los Hyperiidea (116 especies). Hasta el presente, se han descrito 218 especies nuevas en aguas del Caribe, de las cuales 132 son endémicas. Las áreas con mayor diversidad de anfípodos se concentraron a lo largo del caribe Mexicano, Cuba y la costa norte de Sur-América (Venezuela-Colombia); sin embargo, este patron refleja más bien un mayor esfuerzo en la recoleccion de estos organismos y una mayor experticia taxonómica, que un patron específico de distribución del grupo. En general, el conocimiento del grupo se limita a las aguas someras, con muy poca información sobre zonas profundas. En este sentido, las prioridades de investigación regional en este grupo, debe enfocar un mayor esfuerzo en la costa de Centro América y las Antillas Mayores y Menores. Así mismo, es necesario aumentar las recolecciones en aguas profundas y otros ecosistemas particulares como los anquialinos. Por último, es importante aumentar las investigaciones taxonómicas y ecológicas de los taxones que presentan mayor diversidad.

First record of Amphipoda Talitroides topitotum (Burt, 1934) (Gammaridea, Talitridae) in the State of Espírito Santo, Brazil / Primeiro registro do Amphipoda Talitroides topitotum (Burt, 1934) (Gammaridea, Talitridae) no Estado do Espírito Santo, Brasil

Talitroides topitotum (Amphipoda) was introduced in Brazil by silviculture activities. Currently the species is distributed in the states of Paraná, Rio de Janeiro and São Paulo. This paper describes the species' occurrence in the state of Espírito Santo. The objective of this study was to determine the interference of the edge effect on community structure of macroinvertebrates associated with leaf litter, where a T. topitotum female specimen was observed in coffee cultivations in March 2008.

Talitroides topitotum (Amphipoda) foi introduzido no Brasil pelas atividades de silvicultura. Atualmente a espécie está distribuída nos Estados do Paraná, Rio de Janeiro e São Paulo. Este trabalho descreve a ocorrência desta espécie no Estado do Espírito Santo. O objetivo deste estudo foi determinar a interferência do efeito de borda na estruturada comunidade de macroinvertebrados associados ao folhiço, onde um espécime fêmea de T. topitotum foi observado em cultivo de café em março de 2008.

Anfípodos hiperídeos (Crustacea: Peracarida) del Parque Nacional Isla del Coco, Costa Rica, Pacífico Tropical Oriental / Hyperiid amphipods (Crustacea: Peracarida) of the Parque Nacional Isla del Coco, Costa Rica, Eastern Tropical Pacific

Hyperiid amphipods are one of the most frequently encountered pelagic crustaceans and among the most diverse marine zooplankters. To determine the species composition of the hyperiid amphipods dwelling in the waters around Isla del Coco National Park, Pacific Costa Rica, we analyzad 12 zooplankton samples, collected by vertical and horizontals tows with plankton net with mesh sizes of 200 and 500 microns and 49cm mouth diameter. We recorded a total of 22 species belonging to 17 genera and 12 families. A faunistic list of this group is provided together with data on their taxonomy and their distribution both in the surveyed area and in general. Most of the species recorded in this zone have been reported in previous surveys in the Eastern Tropical Pacific region and particularly in oceanic waters of Costa Rica. We found eight species representing new records for Costa Rican waters, thus increasing by 26% (to 38) the number of hyperiid species known from Costa Rica. The most frequent species were Lestrigonus shoemakeri, L. bengalensis, Hyperiodes sibaginis, and Phronimopsis spinifera. We expect that additional samplings both from surface and deep waters will expand the knowledge of the diversity of the group in this important protected area.

Los anfípodos hiperídeos son uno de los grupos de crustáceos pelágicos más frecuentemente encontrados y están entre los más diversos del zooplancton marino. Para determinar la composición de especies de anfípodos hipéridos que habitan las aguas alrededor del Parque Nacional Isla del Coco, Costa Rica, se analizaron 12 muestras de zooplancton. Estas fueron recolectadas mediante arrastres verticales y horizontales con una red de plancton con mallas de 200 y 500 micras y 49cm de diámetro en la boca. Se encontró un total de 22 especies pertenecientes a 17 géneros y 12 familias. Se presenta el listado faunístico de este grupo junto con datos acerca de su taxonomía, su distribución en el área de estudio y su distribución general. La mayor parte de las especies registradas en esta zona han sido reportadas en estudios previos referentes a la región del Pacífico Tropical Oriental y en particular en aguas oceánicas de Costa Rica. Encontramos ocho especies que representan nuevos registros para aguas del Pacífico costarricense, lo que incrementa en un 26% (a 38) el número de especies de hipéridos conocidos en Costa Rica. Las especies más frecuentes fueron Lestrigonus shoemakeri, L. bengalensis, Hyperioides sibaginis y Phronimosis spinifera. Se espera que muestreos adicionales tanto de aguas superficiales como profundas expandan el conocimiento de la diversidad del grupo en esta área protegida.

A new species of Elasmopus (Amphipoda: Hadzioidea: Maeridae) from Suape Harbor, Northeastern Brazilian coast

A new amphipod species of the genus Elasmopus Costa, 1853 is described based on material collected from intertidal rocky shore, near the Suape Harbor, coast of the Brazilian state of Pernambuco. The new species may be recognized by the propodus of gnathopod 2 suboval, slightly tapering distally, palmar margin not defined by a stout seta, spine, or palmar corner, with a subdistal blunt tubercle, posterior margin covered by a dense fringe of plumose setae, and posterior margin of basis of pereopod 7 castelloserrate. This is the ninety-fifth species of the genus Elasmopus described worldwide, the most diverse genus in the family Maeridae Krapp-Schickel, 2008, and the eighth species recorded from Brazilian waters. An identification key to Brazilian species of Elasmopusis also provided.

Uma nova espécie Amphipoda do gênero Elasmopus Costa, 1853 é descrita com base em material coletado da zona entre marés de um costão rochoso, próximo ao Porto de Suape, costado estado brasileiro de Pernambuco. A nova espécie pode ser reconhecida pelo própodo do gnatópo de 2 suboval, estreitando-se de forma suave distalmente, margem palmar não definida por uma cerda grossa, espinho, ou ângulo palmar, comum tubérculo subdistal não agudo, margem posterior coberta por uma franja densa de cerdas plumosas, e margem posterior da base do pereópodo 7 castelosserrado. Esta é a nonagésima quinta espécie do gênero Elasmopus descrita ao redor do mundo, o mais diverso gênero na família Maeridae Krapp-Schickel, 2008, e a oitava espécie registrada para as águas brasileiras. É fornecida também uma chave de identificação para as espécies brasileiras de Elasmopus.

Lípidos en el anfípodo Talorchestia margaritae (Amphipoda: Talitridae) y su relación con la ecología de la especie

Lipids in the amphipod Talorchestia margaritae (Amphipoda: Talitridae) and its relationship with the ecology of the species. T. margaritae, an endemic species inhabiting Venezuelan coasts, plays an important ecological role in plant and animal decomposition. To understand this issue in some animal groups, especially small ones, lipid composition analysis has been an interesting tool to describe their trophic relationships and food preferences. In order to assess this and visualize the components of their diet, we determined the lipid composition differences between males and females and among age classes in this species. Two sandy beaches were selected: Mangle Quemao and Las Mercedes de Paparo, from which sand samples of known volume were collected at the supralittoral area in 2007. Organisms were separated by age and sex classes, and their size, weight, density, biomass, total lipids (TL), lipid classes and fatty acid markers present in their tissues were determined. The sizes were similar for all age classes between the two locations, while the weights were higher for Mangle Quemao. The TL and lipid classes showed similar proportions between sexes, age classes and locations (TL: 3-5%; Phospholipids: 20-30%; Glycolipids: <1%; sterols: 4%). On the other hand, Triglycerides (TAG) were higher in Mangle Quemao, which may be related to the difference between the weights of two locations. The most abundant fatty acid biomarkers in the two studied sites were 16:0 and 18:1(n-9); this last one is characteristic of a carnivorous diet. The other nine markers were identified with changes in their distribution in organisms at Mangle Quemao and between males and females of both populations. Based on observed fatty acids markers we can assume T. margaritae as a generalist carnivore. Those populations were influenced by available food; inducing differences in weight, TAG proportion and markers diversity. Rev. Biol. Trop. 58 (3): 841-855. Epub 2010 September 01.

T. margaritae cumple un papel importante en la descomposición de restos vegetales y animales en las costas venezolanas. El objetivo fue determinar las diferencias en la composición lipídica entre sexos y talla de la especie. Para esto, especímenes de T. margaritae fueron recolectados en la zona supralitoral de dos playas arenosas: Mangle Quemao y las Mercedes de Paparo. Posteriormente se separaron por talla y sexo determinándoles su peso, densidad, biomasa y perfil lipídico. Todas las categorías presentaron tallas similares entre localidades. Los pesos fueron superiores en los organismos de Mangle Quemao. Los lípidos totales presentaron proporciones similares entre sexos, talla y localidad (3-5%), al igual que los fosfololípidos (20-30%), glicolípidos (<1%) y esteroles (4%), exceptuando los triglicéridos (TAG), siendo estos superiores en Mangle Quemao. Esto último pudiendo estar relacionado con la diferencia de pesos entre localidades. Los ácidos grasos más abundantes en ambas localidades fueron 16:0 y 18:1(n-9). Se identificaron otros 9 marcadores con variaciones en su distribución. Con base en los biomarcadores se puede catalogar a T. margaritae como una especie carnívora- generalista, siendo sus poblaciones influenciadas por la disponibilidad de alimento que a su vez, podría inducir diferencias de peso, TAG y biomarcadores.

Lista y referencias de los crustáceos anfípodos (Amphipoda: Gammaridea) del Atlántico occidental tropical

Checklist and references of the Amphipod Crustaceans (Gammaridea) from tropical western Atlantic. The published records of Amphipoda Gammaridea of the tropical western Atlantic region were reviewed and compiled in a checklist. A total of 478 species is recorded (52 families, 199 genera). This adds 20 families and 253 species to the last published list. The families are Ampeliscidae, Amphilochidae, Amphitoidae, Anamixidae, Aoridae, Argissidae, Aristiidae, Bateidae, Biancolinidae, Bogidiellidae, Cheluridae, Colomastigidae, Corophiidae, Cyphocarididae, Cyproideidae, Dexaminidae, Endevouridae, Epimeriidae, Eusiridae, Gammaridae, Hadziidae, Haustoriidae, Hyalellidae, Hyalidae, Hyperiopsidae, Iphimediidae, Isaeidae, Ischyroceridae, Leucothoidae, Liljeborgiidae, Lysianassidae, Megaluropidae, Melitidae, Melphidippidae, Ochlesidae, Oedicerotidae, Pardaliscidae, Phliantidae, Phoxocephalidae, Platyischnopidae, Pleustidae, Podoceridae, Pontoporeiidae, Scopelocheiridae, Sebidae, Stegocephalidae, Stenothoidae, Synopiidae, Talitridae, Uristidae, and Vitjazianidae. Rev. Biol. Trop. 55 (2): 479-498 (Foliación únicamente para la versión digital: 479-528). Epub 2007 June, 29.

Se presenta una lista actualizada de los anfípodos gamarideos del Atlántico occidental tropical, la cual contiene 51 familias y 475 especies. En comparación con trabajos anteriores, el número de familias y especies de esta región se incrementó en 20 y 250, respectivamente. Las familias presentes en la lista son las siguientes: Ampeliscidae, Amphilochidae, Amphitoidae, Anamixidae, Aoridae, Argissidae, Aristiidae, Bateidae, Biancolinidae, Bogidiellidae, Cheluridae, Colomastigidae, Corophiidae, Cyphocarididae, Cyproideidae, Dexaminidae, Endevouridae, Epimeriidae, Eusiridae, Gammaridae, Hadziidae, Haustoriidae, Hyalellidae, Hyalidae, Hyperiopsidae, Iphimediidae, Isaeidae, Ischyroceridae, Leucothoidae, Liljeborgiidae, Lysianassidae, Megaluropidae, Melitidae, Melphidippidae, Ochlesidae, Oedicerotidae, Pardaliscidae, Phliantidae, Phoxocephalidae, Platyischnopidae, Pleustidae, Podoceridae, Pontoporeiidae, Scopelocheiridae, Sebidae, Stegocephalidae, Stenothoidae, Synopiidae, Talitridae, Uristidae y Vitjazianidae.

Contenido proteico en los diferentes estadios embrionarios de Talorchestia margaritae (Amphipoda: Talitridae) durante su desarrollo intra-marsupial / Proteic content in the embryonic stages of Talorchestia margaritae (Amphipoda: Talitridae) during its intramarsupial development

The amphipod Talorchestia margaritae Stephesen, 1948, is a semi-terrestrial species that inhabits decaying organic material along estuarine shores of the Tuy river, Miranda state, Venezuela. We studied the embryonic development of T. margaritae and used biochemical quantitative methods to determine the protein content of embryos in stages of intra-marsupial development, as well as the consumption pattern of these proteins by the embryos. The smallest reproductive females measured 4.6 mm in body length. A low correlation (R2 = 0.2157; p<0.01) was found between female size and number of eggs in the marsupium. The number of eggs and embryos in the marsupium varied between 3 and 12 egg or embryos/female for all female sizes, regardless of stage. Five developmental stages were observed: the uncleaved egg, three embryonic stages and the juvenile stage. Mean embryo size increased significantly during embryo development: from 536.4+or -28.4 ìm at stage I up to 798.1+ or -18.44 ìm at the juvenile stage (stage V). The protein content decreased from an initial mean value of 4.14+ or -0.78 ìg proteins/egg to a final value of 2.02+ or -0.46 ìg protein/juvenile. Most of this decrease occurred between stages I and IV, a pattern which could reflect an initial higher consumption of the proteins as a source of energy and tissue formation. At the final stages (between IV and V), there were no significant differences between the protein content of the embryos.

El anfipodo Talorchestia margaritae Stephesen, 1948, es una especie semi-terrestre, que habita bajo material organico en descomposicion, en la desembocadura del rio Tuy, estado Miranda, Venezuela. Estudiamos el desarrollo embrionario de T. margaritae y determinamos con metodos bioquimicos cuantitativos el contenido de proteinas en los embriones, durante los estadios del desarrollo intramarsupial, asi como su patron de consumo de proteinas. La talla minima de hembras ovadas fue de 4.6 mm de longitud corporal. Se encontro una correlacion baja (R2 igual 0.2157; p menor 0.01) entre la talla de la hembra y el numero de huevos en el marsupio. El numero de huevos y embriones en el marsupio vario entre 3 y 12 huevos o embriones/hembra, para todas las tallas de hembra independientemente del estadio. Se observaron cinco estadios de desarrollo: el huevo no dividido, tres estadios de embriones intramarsupiales y el juvenil. A medida que avanza el desarrollo, hay un incremento significativo de la talla de los embriones, desde un promedio para el estadio I (huevo no dividido) de 536.4 (+ o -28.4) ìm, hasta un promedio de 798.1 (+ o - 18.44) ìm en el estadio V (juvenil). El contenido de proteinas disminuyo desde un promedio inicial de 4.14 (+ o - 0.78) ìg proteinas/huevo, hasta un promedio final de 2.02 (+ o - 0.46) ìg proteina/juvenil. La disminucion es mayor entre los estadios I y IV, pudiendo este patron reflejar una mayor utilizacion inicial de las proteinas como fuente de energia y formacion de tejidos, mientras que en estadios finales, no hay diferencias significativas entre el contenido de proteinas de los estadios IV y V.

Biodiversity of the Gammaridea and Corophiidea (Crustacea: Amphipoda) from the Beagle Channel and the Straits of Magellan: a preliminary comparison between their faunas

Gammaridea and Corophiidea amphipod species from the Beagle Channel and the Straits of Magellan were listed for the first time; their faunas were compared on the basis of bibliographic information and material collected in one locality at Beagle Channel (Isla Becasses). The species Schraderia serraticauda and Heterophoxus trichosus (collected at Isla Becasses) were cited for the first time for the Magellan region; Schraderia is the first generic record for this region. A total of 127 species were reported for the Beagle Channel and the Straits of Magellan. Sixty-two species were shared between both passages (71.3 % similarity). The amphipod species represented 34 families and 83 genera. The similarity at genus level was 86.4 %, whereas 23 of the 34 families were present in both areas. For all species, 86 had bathymetric ranges above 100 m and only 12 species ranged below 200 m depth. In the Beagle Channel, only one species had a depth record greater than 150 m, whereas in the Straits of Magellan, 15 had such a record. The Beagle Channel and the Straits of Magellan contain 57.5 % of the species, 71 % of the genera and 77.3 % of the families of Gammaridea and Corophiidea from the entire Magellan region.

Se confeccionó el primer listado de anfípodos Gammaridea y Corophiidea del Canal Beagle y del Estrecho de Magallanes, y se compararon, en forma preliminar, sus faunas con base en información bibliográfica y material recolectado en una localidad del Canal Beagle (Isla Becasses). Las especies Heterophoxus trichosus y Schraderia serraticauda (recolectadas en Isla Becasses) son citadas por primera vez para la región magallánica; Schraderia representa el primer registro genérico para dicha región. Un total de 127 especies fueron registradas para el Canal Beagle y el Estrecho de Magallanes, compartiendo entre ambos 62 especies, lo que representa una similitud del 71.3 %. El total de las especies pertenece a 34 familias y 83 géneros. La similitud a nivel genérico fue del 86.4 %, mientras que 23 familias estuvieron presentes en ambos pasajes. Del total de especies, 86 presentaron rangos de profundidad menores a los 100 m y sólo 12 especies superaron los 200 m. Sólo una especie tuvo un registro superior a los 150 m de profundidad en el Canal Beagle, mientras que 15 superaron dicha profundidad en el Estrecho de Magallanes. En el Canal Beagle y el Estrecho de Magallanes se registró el 57.5 % de las especies, 71 % de los géneros y 77.3 % de las familias conocidas para la región magallánica.

Structural variation in the brown alga Sargassum cymosum and its effects on associated amphipod assemblages

The presence of diverse biological substrates adds complexity to coastal landscapes and increases the number of ecological niches that can be used by the mobile epifauna. Studies on the influence of structural complexity have focused mainly on algal host species, but there is little information about the influence of intraspecific structural variation on the associated mobile epifauna. In this work, we examined whether intraspecific variation in the brown alga Sargassum cymosum influenced the structure of amphipod assemblages on two shores with different wave exposure. At least 15 fronds were randomly sampled at Fortaleza and Perequê-Mirim beaches, on the Atlantic coast of São Paulo state, southeastern Brazil, and 12 variables were measured for each alga. The amphipods were identified and counted. The greatest structural variation in S. cymosum occurred within shores, whereas the differences between shores were mainly related to algal size. These characteristics influenced amphipod assemblages differently on each shore, with the greatest effects being associated with variables related to morphological complexity, such as holdfast size, the number and size of branches, and the extent of cover by sessile colonial animals. These findings show that monospecific algal banks are not homogeneous, and that morphological differences and interactions with other biological substrates can influence the mobile epifaunal assemblages.

A presença de substratos biológicos aumenta a complexidade dos ambientes costeiros, proporcionando maior número de nichos ecológicos para a epifauna vágil. Estudos sobre os efeitos da complexidade estrutural das algas têm enfocado principalmente as espécies presentes entre os seus ramos, porém há poucos dados sobre a influência da variação estrutural intra-específica sobre essa fauna. Neste trabalho, foi analisada a influência da variação da alga parda Sargassum cymosum sobre a estrutura da assembléia de anfípodes entre duas praias com diferentes graus de exposição às ondas, e em cada uma delas, no SE do Brasil. Pelo menos 15 frondes foram individualmente coletadas aleatoriamente nos costões das praias de Fortaleza e Perequê-Mirim, e diversas variáveis (12) foram medidas para cada fronde de alga. Os anfípodes foram identificados e contados. As maiores variações nas características de S. cymosum foram obtidas em cada praia, enquanto que diferenças entre as praias foram principalmente relacionadas ao tamanho das algas. Estas características influenciaram as assembléias de anfípodes de maneira diferente em cada praia, sendo que os maiores efeitos foram atribuídos a variáveis relacionadas com a morfologia das algas como o tamanho do apressório, o número e tamanho dos ramos e a cobertura por organismos coloniais sésseis. Portanto, bancos monoespecíficos de algas não são homogêneos e tanto as diferenças morfológicas como as interações com outros substratos biológicos podem influenciar as assembléias da epifauna vágil.

Efecto de sedimentos naturales enriquecidos con zinc, en modelos aislados y en microcosmos, sobre tres especies de invertebrados bentónicos / Effect of zinc-enriched sediments, in open and isolated systems, on three species of benthonic invertebrates

Availability of toxics in aquatic bodies is limited by the physicochemical characteristics of sediments and water, as well as by the interactions between the different xenobiotics and inhabits species. The aim of this work was to relate the effect produced by zinc (Zn) spiked in sediments of the Ignacio Ramirez dam (PIR), in isolated and microcosms models, on ATP concentration of three benthic organisms with the metal biodisponibility. The selected species were a crustacean, an annelid and a mollusk: Hyalella azteca (Amphipoda: Hyalellidae), Limnodrilus hoffmeisteri (Oligochaeta: Tubificidae) and Stagnicola attenuata (Basommatophora: Lymnaeidae), species that are found at high proportions in the reservoir and use different spaces in the benthos. Samples of sediments and organisms were collected from the PIR during the dry season (February of 1999). Metal concentration (Zn, Fe, Cu and Ni), pH, texture, particle size, total nitrogen and organic matter were determined in sediments. Sublethal studies were carried out using two types of static systems (organisms isolated and in microcosms). Both models contained PIR sediments enriched with Zn (nominal concentration of 0.8129 mg/kg) and synthetic water in a proportion of 1:4. The test organisms were added to the systems once the equilibrium was reached (2 hr) considering the biomass quantity with respect to volume (1.0 g of organism by each 100 ml of water:sediment). After 0, 12, 24, 36, 48 and 72 hr of exposure, samples of sediment and hydrobionts were taken, and Zn content was quantified by atomic absorption. ATP concentration was also determined in organisms. The effect produced by natural sediments spiked with Zn is increased by the presence of more than one specie in the system (microcosm). With respect to Zn levels, two of the organisms tend to lose this metal in isolated and microcosm models, probably as a regulation strategy in its accumulation, as well as Fe presence in the reservoir sediments. Therefore...

En los cuerpos acuáticos la disponibilidad de los tóxicos es limitada por las características fisicoquímicas de los sedimentos y agua, así como por las interacciones entre los diversos xenobióticos y entre las especies que los habitan. Por lo anterior, el objetivo del presente trabajo fue relacionar el efecto producido por el zinc (Zn) sembrado en sedimentos del embalse Ignacio Ramírez (PIR), en modelos aislados y en microcosmos, sobre el ATP de res organismos bentónicos con la biodisponibilidad del metal. Las especies seleccionadas fueron: Hyalella azteca, Limnodrilus hoffmeisteri y Stagnicola attenuata, dado que se encuentran en altas proporciones en el embalse y ocupan espacios diferentes en el bentos. Las muestras de sedimentos y organismos se colectaron en la estación de sequía (febrero de 1999). A los primeros se les determinó el pH, textura, tamaño de partícula, nitrógeno total, materia orgánica y concentración de metales (Zn, Fe, Cu y Ni). Posteriormente se realizó un estudio de toxicidad subletal utilizando dos tipos de sistemas estáticos (organismos aislados y en microcosmos). Ambos modelos contenían sedimentos de la PIR enriquecidos con Zn (concentración nominal de 0.8129 mg/kg) y agua sintética en una proporción de 1:4. Los organismos de prueba fueron adicionados una vez alcanzado el equilibrio (2 hr) considerando la cantidad de biomasa con respecto al volumen (1.0 g de organismo por cada 100 ml de agua:sedimento). Después de 0, 12, 24, 36, 48 y 72 hr de exposición se tomaron muestras del sedimento y de los hidrobiontes, a los cuales se les cuantificó el contenido de Zn por absorción atómica. A los organismos también se les determinó la concentración de ATP. Los resultados obtenidos muestran que el efecto producido por los sedimentos naturales enriquecidos se ve potenciado por la presencia de más de una especie en el sistema (microcosmos). Con respecto a los niveles de Zn, dosde los organismos (L. hoffmeisteri y S. attenuata) tienden a...

Metacercarias de la familia Microphallidae (Trematoda: Digenea) en el anfípodo Hyale grandicornis en la costa de Maule, Chile Central / Metacercariae of the family microphallidae (Trematoda: Digenea) in the amphipod Hyale grandicornis from the coast of Maule, Central Chile

Los digeneos presentan ciclos biológicos complejos con 2 fases reproductivas y varios hospedadores, como moluscos y crustáceos (hospedadores intermediarios) y vertebrados (hospedadores definitivos). A pesar de los numerosos registros de digeneos en fases adultas en distintas especies hospedadoras, hay muy pocos registros en invertebrados y ninguno en crustáceos. Con el fin de aportar información sobre alguna de la fases juveniles de digeneos, se revisaron 98 anfípodos Hyale grandicornis (Krõyer, 1845) recolectados desde pozas intermareales en la costa de Maule, Chile Central. De estos el 64,3 por ciento albergaban entre 1 y 25 metacercarias por amfípodo. Se reconocieron 3 tipos de metacercarias de acuerdo a su forma (ovalada y esféricas) y tamaño (entre 200 y 375 µm). Para identificarlas, las metacercarias fueron incubadas y eclosionadas artificialmente. La morfología de los digeneos juveniles corresponde a Microphallidae: un tipo correspondería a Maritrematinae, y los otros dos podrían corresponder a Microphallinae. Estos digeneos principalmente son parásitos de aves y algunos son de peces, anfibios o mamíferos, sin embargo no hay registros de estos parásitos en ningun vertebrado en Chile. Varias especies de aves como Larus, Fulica y Phalacrocorax que habitan comúnmente en las costas de Maule, podrían ser las hospedadoras definitivas de estos digeneos.

Digeneans have complex life cycles with 2 reproductive phases and 2-3 hosts such as molluscs, crustaceans and vertebrates. Despite numerous records of adult digeneans from many host species of Chile, there are few records in invertebrates. The aim of this study is to provide information about juvenile phases of digeneans in the amphipod Hyale grandicornis (Kröyer, 1845). Ninety-eight amphipods were collected from intertidal pools at Maule, central coast of Chile. Sixty-four percent of the amphipods were parasitized with 1-25 metacercariae/host individual. Three types metacercariae were distinguished according their shape (spherical or ovalated) and size (between 200 to 375 µm legth). To identify them, the metacercariae were incubated and artificially opened. The morphology of juvenile digeneans of the 3 types of metacercariae corresponded to the family Microphallidae. One type of metacercaria may belong to Maritrematinae; the other two may belong to Microphallinae. The definitive hosts for Microphallidae are principally birds, although some species can be found in fishes, amphibians or mammals. In Chile, there are no records of these digeneans in any group of hosts. In the Coast of Maule usually inhabit many bird species such as Larus, Fulica, and Phalacrocorax genera, so that some of them could be definitive hosts of these digeneans.

Composition and seasonality of an amphipod community associated to the algae Bryocladia trysigera

The monthly fluctuations of amphipods associated to the algae Bryocladia trysigera was described from March 1997 to February 1998 at the rocky shore known as Poço de Anchieta in the Peruíbe Beach, Itanhaém, Southeastern Brazil. A total of 75,344 individuals were sampled, belonging to 10 species and 9 families. Three species dominated the phytal in number: Hyale nigra, Caprella danileviskii and Caprella penantis. Despite the alternation in dominance of the 3 most abundant species, the amphipod species composition remained generally unchanged, so that the majority of the species were observed in all sampling months. The temporally changing pattern of the community structure, with a decline in amphipod abundance in winter followed by an increase in spring, was probably due to a higher predation pressure in winter period

Redescription of the freshwater amphipod Hyalella faxoni from Costa Rica (Crustacea: Amphipoda: Hyalellidae)

Hyalella faxoni Stebbing, 1903 from Costa Rica is redescribed. The species was previously in the synonymy of Hyalella azteca (Saussure, 1858). The morphological differences between these two species are discussed.

A new species of Hyalella from the Andes in Perú (Crustacea: Amphipoda: Hyalellidae)

Hyalella pauperocavae n. sp. from Huancayo, Perú, is described. Five other epigean freshwater amphipods have been described from Peru (excluding Lake Titicaca), but the lack of type material and poor descriptions do not allow the assignment of the species described here to any of the names known for the area.