ABSTRACT
Knowledge of seasonal dynamics and composition of meroplankton (larvae of benthic invertebrates) is rather limited for sub-Antarctic regions. We studied the seasonal dynamics of meroplankton in a sub-Antarctic proglacial basin (Gallegos Sound, Chile), by examining changes in the meroplankton community in relation to hydrographic variables along four sampling cruises between early winter 2010 and late winter 2011. The local meroplankton community was composed of 39 larval morphotypes distributed among 11 major taxa, being polychaetes the best represented (15 larvae morphotypes), and bivalve the most abundant. We found distinct seasonal differences in terms of meroplanktonic composition and abundance, with higher abundance and larval morphotype number during austral spring and late winter, and lower in summer and early winter. The pattern observed for meroplankton was directly related to seasonal variations of fluorescence of chlorophyll a and temperature. We found meroplankton abundances lower than those of other sub- and Polar environments. However, meroplanktonic temporal dynamics showed a common pattern for sub- and Polar fjords, suggesting a strong link between benthic spawning and the occurrence of phytoplankton blooms. Supplementary Information: The online version contains supplementary material available at 10.1007/s00300-021-02823-6.
ABSTRACT
How to improve habitat quality for wildlife is of particular importance in areas dedicated to food production, due to increasing pressures of global demands associated to human population growth. Semi-intensive aquaculture ponds can provide a potentially important foraging habitat for migratory shorebirds throughout the non-breeding season. Therefore, understanding the availability of benthic invertebrates in aquaculture ponds will help to identify proper management decisions for shorebird conservation. We used an exclosure experiment during the first three days after shrimp harvesting at semi-intensive aquaculture ponds in north-west Mexico to assess shorebird predation on benthic invertebrates. We found that shorebird predation did not deplete total benthic invertebrate density (particularly polychaete worms), but significantly affected the prey size distributions and biomass in the ponds during a short-time window of just three days. Shorebirds removed 0.6 g ash-free dry weight m-2, equivalent to 43% of the initial biomass and showed high selectivity for polychaetes larger than >40 mm as prey, potentially explaining the absence of large polychaetes at the end of the experiment. This depletion was the likely cause of the daily decrease observed in overall density of foraging shorebirds at recently harvested ponds. These results can serve to identify management actions that allow an extended use of semi-intensive aquaculture ponds as foraging sites for migratory shorebirds during the non-breeding season, with potential applications to develop standards for a friendlier aquaculture management.
Subject(s)
Invertebrates , Ponds , Animals , Aquaculture , Ecosystem , Humans , MexicoABSTRACT
Tributaries may serve as richness source for the river main channel and the zoobenthos community is a good tool to verify this kind of pattern. In this study, we aimed to characterize the benthic invertebrate assemblage in three tributaries associated to the Paraná River main channel, focusing in Oligochaeta community. We hypothesized that (i) in tributaries, Oligochaeta are richer than the main river (Paraná River) and (ii) dammed tributary (Paranapanema River) is poorly diverse than the others. Samples were conducted in Paranapanema, Baía and Ivinhema tributaries using a modified Petersen grab along three transects (samples conducted inside the tributary, in the mouth of each tributary and inside Paraná River). To analyze (i) the difference between the richness and density among the tributaries and the Paraná River and (ii) effect of each tributary transect on the Oligochaeta richness we used a nonparametric Kruskal-Wallis test. Changes in environmental variables and in richness and composition of Oligochaeta were summarized by Canonic Correspondence Analysis. It was registered 21 different benthic invertebrates taxa, being Oligochaeta assemblage with the highest density. Within Oligochaeta, Narapa bonettoi was the most abundant species, followed by Haplotaxis aedochaeta and Paranadrilus descolei. In our results we refused both hypotheses, because we did not found significant differences for richness and density between the tributaries and the main river, and also no difference between the three transects of each tributary were found. However, the tributaries less influenced by damming, especially the Baía recorded high richness. This corroborates their importance to diversity in the floodplain and the species of Oligochaeta reflect the peculiar characteristics of habitats within each tributaries.(AU)
Tributários podem servir como fonte de riqueza para o canal principal do rio e a comunidade de zoobentos é uma boa ferramenta para verificar esse tipo de padrão. Neste estudo, que teve como objetivo caracterizar as assembleias de invertebrados bentônicos em três tributários associados ao canal principal do rio Paraná, com foco na comunidade de Oligochaeta. Nossa hipótese é que (i) em afluentes a assembleia de Oligochaeta apresenta maior riqueza do que o rio principal (rio Paraná), e (ii) o tributário represado (Rio Paranapanema) é menos diverso do que os demais. As amostras foram realizadas nos tributários Paranapanema, Baía e Ivinhema utilizando uma draga Petersen modificado ao longo de três transectos (amostras realizadas dentro do afluente, na boca de cada afluente e no interior do Rio Paraná). Para analisar (i) a diferença na riqueza e densidade entre os afluentes e o rio Paraná, e (ii) o efeito de cada transecto do tributário sobre a riqueza Oligochaeta foi utilizado um teste de Kruskal-Wallis não paramétrico. Mudanças nas variáveis ambientais e na riqueza e composição de Oligochaeta foram resumidos por análise de correspondência canônica. Foi registrados 21 diferentes táxons invertebrados bentônicos, sendo assembleia de Oligochaeta com a maior densidade. Dentro de Oligochaeta Narapa bonettoi foi à espécie mais abundante, seguido por Haplotaxis aedochaeta e Paranadrilus descolei. Em nossos resultados, ambas as hipóteses foram refutadas, visto que não mostraram diferenças na riqueza e densidade entre os tributários e o canal principal, e nem entre os três transectos dos tributários. Entretanto, os tributários menos influenciados pelo represamento, principalmente o Baía, registraram riqueza elevada. Isso corrobora sua importância para a diversidade na planície de inundação e as espécies de Oligochaeta refletem as características peculiares dos habitats dentro de cada tributátio.(AU)
Subject(s)
Animals , Biodiversity , Oligochaeta/classification , Brazil , Oligochaeta/physiology , Population Density , Population Dynamics , Rivers , Seasons , Water MovementsABSTRACT
Tributaries may serve as richness source for the river main channel and the zoobenthos community is a good tool to verify this kind of pattern. In this study, we aimed to characterize the benthic invertebrate assemblage in three tributaries associated to the Paraná River main channel, focusing in Oligochaeta community. We hypothesized that (i) in tributaries, Oligochaeta are richer than the main river (Paraná River) and (ii) dammed tributary (Paranapanema River) is poorly diverse than the others. Samples were conducted in Paranapanema, Baía and Ivinhema tributaries using a modified Petersen grab along three transects (samples conducted inside the tributary, in the mouth of each tributary and inside Paraná River). To analyze (i) the difference between the richness and density among the tributaries and the Paraná River and (ii) effect of each tributary transect on the Oligochaeta richness we used a nonparametric Kruskal-Wallis test. Changes in environmental variables and in richness and composition of Oligochaeta were summarized by Canonic Correspondence Analysis. It was registered 21 different benthic invertebrates taxa, being Oligochaeta assemblage with the highest density. Within Oligochaeta, Narapa bonettoi was the most abundant species, followed by Haplotaxis aedochaeta and Paranadrilus descolei. In our results we refused both hypotheses, because we did not found significant differences for richness and density between the tributaries and the main river, and also no difference between the three transects of each tributary were found. However, the tributaries less influenced by damming, especially the Baía recorded high richness. This corroborates their importance to diversity in the floodplain and the species of Oligochaeta reflect the peculiar characteristics of habitats within each tributaries.
Tributários podem servir como fonte de riqueza para o canal principal do rio e a comunidade de zoobentos é uma boa ferramenta para verificar esse tipo de padrão. Neste estudo, que teve como objetivo caracterizar as assembleias de invertebrados bentônicos em três tributários associados ao canal principal do rio Paraná, com foco na comunidade de Oligochaeta. Nossa hipótese é que (i) em afluentes a assembleia de Oligochaeta apresenta maior riqueza do que o rio principal (rio Paraná), e (ii) o tributário represado (Rio Paranapanema) é menos diverso do que os demais. As amostras foram realizadas nos tributários Paranapanema, Baía e Ivinhema utilizando uma draga Petersen modificado ao longo de três transectos (amostras realizadas dentro do afluente, na boca de cada afluente e no interior do Rio Paraná). Para analisar (i) a diferença na riqueza e densidade entre os afluentes e o rio Paraná, e (ii) o efeito de cada transecto do tributário sobre a riqueza Oligochaeta foi utilizado um teste de Kruskal-Wallis não paramétrico. Mudanças nas variáveis ambientais e na riqueza e composição de Oligochaeta foram resumidos por análise de correspondência canônica. Foi registrados 21 diferentes táxons invertebrados bentônicos, sendo assembleia de Oligochaeta com a maior densidade. Dentro de Oligochaeta Narapa bonettoi foi à espécie mais abundante, seguido por Haplotaxis aedochaeta e Paranadrilus descolei. Em nossos resultados, ambas as hipóteses foram refutadas, visto que não mostraram diferenças na riqueza e densidade entre os tributários e o canal principal, e nem entre os três transectos dos tributários. Entretanto, os tributários menos influenciados pelo represamento, principalmente o Baía, registraram riqueza elevada. Isso corrobora sua importância para a diversidade na planície de inundação e as espécies de Oligochaeta refletem as características peculiares dos habitats dentro de cada tributátio.
Subject(s)
Animals , Biodiversity , Oligochaeta/classification , Brazil , Oligochaeta/physiology , Population Density , Population Dynamics , Rivers , Seasons , Water MovementsABSTRACT
The main goal of this research was to obtain baseline field data of the composition of sponges, corals, and gorgonian assemblages that can be used as a reference for future analyses of anthropogenic impact. We tested the hypothesis that relatively homogeneous and well preserved reef units can present notable natural variability in the composition of their communities which are unassociated with changes in land proximity or a human impact gradient. Research was carried out in July 2006 at Los Colorados reef, located in the northwestern region of Pinar del Río Province, Cuba at 12 sampling stations. The biotopes selected were crest, terrace edge and spur and grove. Ecological indicators were diversity of corals, species composition, density of corals, hydrocorals, gorgonians and sponges, and density of selected coral species. A total of 2659 colonies of scleractineans corals representing 36 species were counted. The most abundant species in the crest biotope were Millepora alcicornis, Acropora palmata and Porites astreoides; in the terrace edge and spur and grove, the most abundant species were Siderastrea siderea, Stephanocoenia intersepta, Porites astreoides, Agaricia agaricites and Montastraea cavernosa. We found differences among sites for several indicators (e.g. density of corals, sponges and gorgonians and for selected species), but they could not be associated to any gradient of land influence or human impact. Therefore, sites inside a relatively homogeneous reef unit can present notable natural differences in the composition of their communities. Rev. Biol. Trop. 58 (2): 621-634. Epub 2010 June 02.
El objetivo principal de la investigación fue obtener una línea base de la composición de las comunidades de esponjas, corales y gorgonias que pueda ser utilizada como referencia para futuros análisis de impacto antrópico. Nuestra hipótesis es que un arrecife relativamente homogéneo y bien conservado, presenta una variabilidad natural notable en la composición de sus comunidades, lo cual no está asociado con cambios en la proximidad a tierra o a un gradiente de impacto humano. La investigación se llevó a cabo en julio de 2006, en 12 estaciones de muestreo ubicadas en el arrecife de Los Colorados, en la región noroccidental de la Provincia de Pinar del Río, Cuba. Los biotopos seleccionados fueron cresta, veril y camellones. Los indicadores ecológicos estimados fueron: diversidad de corales, composición por especies, densidad de corales, hidrocorales, gorgonias y esponjas, y densidad de especies de corales seleccionadas. Se contaron 2 659 colonias de corales escleractíneos pertenecientes a 36 especies. Las especies más abundantes en el biotopo de cresta fueron: Millepora alcicornis, Acropora palmata y Porites astreoides; mientras que en el veril y los camellones fueron Siderastrea siderea, Stephanocoenia intersepta, Porites astreoides, Agaricia agaricites y Montastraea cavernosa. Entre sitios, se encontraron diferencias significativas estadísticamente para varios indicadores (densidad de corales, esponjas y gorgonias y densidad de especies seleccionadas), pero ello no pudo asociarse con ningún gradiente de uso de la tierra o de impacto humano. Por lo tanto, sitios dentro de un arrecife relativamente homogéneo pueden presentar diferencias notables en la composición de sus comunidades.