ABSTRACT
Abstract The fauna communities of ephemeral pools in southern Chile are characterized by heterogeneity of crustacean taxa; nevertheless, no detailed studies exist of their community structure. The aim of the present study was to analyze the crustacean community structure in two groups of ephemeral pools (Puaucho and Nigue pools) in the coastal zone of the Araucanía region. A correlation matrix was made by species abundance against temperature, conductivity, pH and total dissolved solids. In a second step, a null model for species co-occurrence was applied to the total data and to each group. The results for total data revealed a significant direct relation between the abundance of H. costera, C. dubia and Mesocyclops. For the Puaucho pools, the same results were found together with direct associations with total dissolved solids, conductivity and pH. Finally, different results were found for the Nigue pools, with no clear significant associations, either direct or indirect, between the abundance of different crustacean taxa and abiotic parameters. These results were supported by the co-occurrence null model analysis, which revealed the presence of regulator factors for the total data, and for each of the two groups. Ecological topics are discussed with emphasis on meta-community dynamics.
Resumo As comunidades faunísticas das lagoas efêmeras do sul do Chile são caracterizadas pela heterogeneidade dos seus táxons. Entretanto, estudos detalhados da sua estrutura de comunidade ainda não existem. O objetivo do presente estudo foi analisar a estrutura da comunidade de crustáceos em dois grupos de lagoas efêmeras (Puaucho e Nigue) na zona costeira da região de Araucanía. A matriz de correlação foi feita com a abundância das espécies em função da temperatura, condutividade, pH e sólidos totais dissolvidos. Num segundo passo, um modelo nulo para as espécies de coocorrência foi aplicado aos dados totais e para cada grupo. Os resultados para os dados totais revelaram uma relação direta e significativa entre a abundância de H. costera, C. dubia e Mesocyclops. Para as lagoas Puaucho, os mesmos resultados foram encontrados, juntamente com associações diretas com sólidos totais dissolvidos, condutividade e pH. Finalmente, diferentes resultados foram encontrados para as lagoas Nigue, sem associações significativas claras, diretas ou indiretas entre a abundância de diferentes táxons de crustáceos e parâmetros abióticos. Estes resultados foram suportados pela análise de modelo de coocorrência nula, a qual revelou a presença de fatores reguladores para o total de dados, e para cada um dos dois grupos. Temas ecológicos são discutidos com ênfase na dinâmica de meta-comunidade.
Subject(s)
Animals , Crustacea/classification , Seawater/chemistry , Temperature , Chile , Ecosystem , Biodiversity , Hydrogen-Ion Concentration , Marine Biology/classification , Minerals/analysisABSTRACT
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.
Subject(s)
Zooplankton/classification , Amphipoda/classification , Biodiversity , Costa RicaABSTRACT
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.
Subject(s)
Animals , Amphipoda/classification , Biodiversity , Amphipoda/physiology , Argentina , SeawaterABSTRACT
The composition, abundance, diversity and density of benthonic peracarid crustaceans were studied in the Orinoco river delta, Venezuela. Samples were collected at 18 sites distributed in five areas: one at the high delta, two at the medium sector and two at the low delta. Two field seasons were included: high waters (18-28 November 2002) and low waters (8-19 May 2003). Three samples were dredged at each sampling site, identifying more than 510 specimens belonging to eight families and 11 species: Amphipoda (three families, six species), Isopoda (one family, one species), Tanaidacea (two families, three species), Cumacea (one family) and Mysida (one family, one species). Two species (Discapseudes surinamensis and Halmyrapseudes spaansi) and an unidentified species of Kalliapseudes are new records for Venezuela. Their density and distribution suggest that a salinity gradient influenced longitudinal distribution: greater densities and species richness were in the lower delta, near the mouth of the Mariusa and Winikina rivers.
Para evaluar la composición, abundancia, diversidad y densidad de crustáceos peracáridos en los sedimentos de la región del delta del río Orinoco (Venezuela), establecimos cinco áreas de muestreo: una en el alto delta, dos en el sector medio y dos en el bajo delta (18 estaciones). Hicimos dos muestreos de campo: época de aguas altas o lluvia (18-28 noviembre/2002) y aguas bajas o sequía (8-19 de mayo, 2003). Tomamos tres muestras de bentos mediante dragas, identificando un total de 515 individuos, pertenecientes a 8 familias y 11 especies en total: Amphipoda (tres familias, seis especies), Isopoda (una familia, una especie), Tanaidacea (dos familias, tres especies), Cumacea (una familia) y Mysida (una familia, una especie), de las cuales dos fueron nuevas citas para el país: Discapseudes surinamensis y Halmyrapseudes spaansi, así como una especie no identificada de Kalliapseudes. La densidad y distribución de estos organismos sugiere la existencia de gradientes de influencia marina, con las mayores densidades y riqueza de especies en áreas cercanas a las desembocaduras de los caños Mariusa y Winikina.
Subject(s)
Animals , Biodiversity , Isopoda/classification , Isopoda/physiology , Population Density , Rivers , Species Specificity , VenezuelaABSTRACT
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.
Subject(s)
Animals , Amphipoda/physiology , Sargassum/growth & development , Amphipoda/classification , Brazil , Population Density , Population Dynamics , Principal Component AnalysisABSTRACT
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.
Subject(s)
Animals , Amphipoda/parasitology , Trematode Infections/veterinary , Trematoda , Chile , TrematodaABSTRACT
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.
Flutuações mensais de Amphipoda associados à alga Bryocladia trysigera são descritas. As coletas foram realizadas no período de março de 1997 a fevereiro de 1998 no costão rochoso do Poço de Anchieta na Praia de Peruíbe, Itanhaém (SP). Foram coletados 75.344 indivíduos, identificados em 9 famílias e 10 espécies. Três espécies dominaram numericamente: Hyale nigra, Caprella danileviskii e Caprella penantis. Embora tivesse sido registrada alternância na dominância dessas espécies, foi observada pequena variação na composição específica nos meses amostrados. A variação temporal na estrutura da comunidade, com o declínio da abundância de Amphipoda no inverno, seguido de aumento na primavera, pode ser causada pela maior pressão de predação no inverno.