Zooplâncton do estuário do Pina (Recife-Pernambuco-Brasil): composição e distribuição temporal

Composieionand daily variation of zooplankton in the estuary of Pina (Brazil- PE) was studied based on 200L of water filtered at surface through a net mesh size of 69 Jlm, during the dry (January-February/91) and the rainy (June-July/91) seasons. The samplcs were collected with time interval of three hours, during a daylight period. Concurrent hydrological data were obtained. Nineteen taxon of zooplankton were registered, including meroplankton, of which the most abundant was Favella ehrenbergi, followed by Brachionus plicatilis, Copepoda nauplii and Oithona osvaldocnlzi (♀). Higher quantitatives values occured in the dry reason. The maximum registered was 411,7490rg.m-3 and the minimum 2,6230rg.m-3 . The tidal currents were the main factor influencing the zooplankton spacial variation. Specific diversity was low, highlighting selcctive processes in the Pina estuary.Estudos sobre a composição e variação diurna do zooplâncton do estuário do Pina (PE) foram reali;r.ados, baseando-se em 200 litros de água superficial, coletada e filtrada em uma rede com malha de 69 11m de abertura, durante os períodos seco Uaneiro e fevereiro/91) e chuvoso Uunho e julho/91), em um ciclo diurno de 12 h. Paralelamente, foram coletados dados hidrolÓgicos. O zooplâncton esteve representado por 19 taxa, além do meroplâncton. Destacaram-se Favella ehrenbergi, Brachionus plicatilis, Copepoda nauplii e Oithona osvaldocnlzi (♀). Valores quantitativos mais altos foram registrados no peJíodo seco. O máximo registrado foi de 411.7490rg.m-3 e o mínimo 2.6230rg.m-3 .As correntes de marés foram as principais responsáveis pela variação espacial do zooplâncton. A diversidade específica foi baixa, evidenciando processos seletivos no estuário

COMPOSITION, BODY-SIZE STRUCTURE AND BIOMASS OF ZOOPLANKTON IN A HIGH-ELEVATION TEMPORARY POND (MINAS GERAIS, BRAZIL)

Small ponds are vital inland water bodies, recognized as small repositories of freshwater biodiversity, but neglected in terms of conservation. Although high-elevation ponds are difficult to sample and monitor, it is important to extend their study, in view of their importance to aquatic biodiversity. The aim of this study was to analyze the composition, size structure biomass and diversity of zooplankton community in a temporary pond (Lagoa Seca) of a low-alpine area in the southern part of Serra do Espinhaço mountain in Minas Gerais State, Brazil. Three ecological aspects were analyzed: (I) the taxonomic composition of the zooplankton assemblage, (II) the size structure and biomass of the main groups in the zooplankton community and (III) whether the morphometric characteristics and biomass of the zooplankton result from the dominance of the microzooplankton, as expected in habitats subjected to frequent and strong disturbances, such as temporary ponds. Zooplankton samples were taken during the rainy period (Oc­tober 2010 to January 2011) in different mesohabitats, from the shallowest areas covered by emergent macrophytes to the open water area covered mainly by submerged macrophytes. The zooplankton community consisted of a small number of taxa (29). Rotifera showed the highest richness, with 21 taxa recorded, of which the most constant species were the cosmopolitan Lecane lunaris, L. obtusa and Lepadella patella. Among the Cladocera, Bosmina freyi and Moina minuta were the pelagic species recorded. The other cladoceran species observed are associated with littoral vegetation, and represented mainly by Alona ossiani, Chydorus pubescens, Ephemeroporus tridentatus and Ilyocryptus spinifer. The zooplankton biomass was very low (the maximum dry weight, observed at the peak of the rainy period in January was 62 ?g.m-3). The zooplankton community was dominated by the microzooplankton, with the maximum body length below 900 ?m. This assemblage was very changeable in the short term, both in numerical density and size structure, probably because of the highly variable hydrological regime of the pond. The results from zooplankton composition, including the first record of the rotifer Microcodon clavus to Minas Gerais state and the second in Brazil, highlighted the important role that high-elevation temporary ponds can play as aquatic biodiversity reserves. These unique ecosystems deserve greater efforts of research and monitoring, including studies of their hydrological pat­terns, biological diversity, and adaptive mechanisms of the zooplankton community.Small ponds are vital inland water bodies, recognized as small repositories of freshwater biodiversity, but neglected in terms of conservation.  Although high-elevation ponds are difficult to sample and monitor, it is important to extend their study, in view of their importance to aquatic biodiversity. The aim of this study was to analyze the composition, size structure biomass and diversity of zooplankton community in a temporary pond (Lagoa Seca) of a low-alpine area in the southern part of Serra do Espinhaço mountain in Minas Gerais State, Brazil. Three ecological aspects were analyzed: (I) the taxonomic composition of the zooplankton assemblage, (II) the size structure and biomass of the main groups in the zooplankton community and (III) whether the morphometric characteristics and biomass of the zooplankton result from the dominance of the microzooplankton, as expected in habitats subjected to frequent and strong disturbances, such as temporary ponds. Zooplankton samples were taken during the rainy period (October 2010 to January 2011), in different mesohabitats, from the shallowest areas covered by emergent macrophytes to the open water area, covered mainly by submerged macrophytes. The zooplankton community consisted of a small number of taxa (29). Rotifera showed the highest richness, with 21 taxa recorded, of which the most constant species were the cosmopolitan: Lecane lunaris, L. obtusa and Lepadella patella. Among the Cladocera, Bosmina freyi and Moina minuta were the pelagic species recorded. The other cladoceran species observed are associated with littoral vegetation, and represented mainly by Alona ossiani, Chydorus pubesceus, Ephemeroporus tridentatus and Ilyocryptus spinifer. The zooplankton biomass was very low (the maximum dry weight, observed at the peak of the rainy period in January was 62 µg.m-3). The zooplankton community was dominated by the microzooplankton, with the maximum body length below 900 µm. This assemblage was very changeable in the short term, both in numerical density and size structure, probably because of the highly variable hydrological regime of the pond.  The results from zooplankton composition, including the first record of the rotifer Microcodon clavus to Minas Gerais state and the second in Brazil, highlightedt the important role that high-elevation temporary ponds can play as aquatic biodiversity reserves. These unique ecosystems deserve greater efforts of research and monitoring, including studies of their hydrological patterns, biological diversity and adaptive mechanisms of the zooplankton community.Small ponds are vital inland water bodies, recognized as small repositories of freshwater biodiversity, but neglected in terms of conservation.  Although high-elevation ponds are difficult to sample and monitor, it is important to extend their study, in view of their importance to aquatic biodiversity. The aim of this study was to analyze the composition, size structure biomass and diversity of zooplankton community in a temporary pond (Lagoa Seca) of a low-alpine area in the southern part of Serra do Espinhaço mountain in Minas Gerais State, Brazil. Three ecological aspects were analyzed: (I) the taxonomic composition of the zooplankton assemblage, (II) the size structure and biomass of the main groups in the zooplankton community and (III) whether the morphometric characteristics and biomass of the zooplankton result from the dominance of the microzooplankton, as expected in habitats subjected to frequent and strong disturbances, such as temporary ponds. Zooplankton samples were taken during the rainy period (October 2010 to January 2011), in different mesohabitats, from the shallowest areas covered by emergent macrophytes to the open water area, covered mainly by submerged macrophytes. The zooplankton community consisted of a small number of taxa (29). Rotifera showed the highest richness, with 21 taxa recorded, of which the most constant species were the cosmopolitan: Lecane lunaris, L. obtusa and Lepadella patella. Among the Cladocera, Bosmina freyi and Moina minuta were the pelagic species recorded. The other cladoceran species observed are associated with littoral vegetation, and represented mainly by Alona ossiani, Chydorus pubesceus, Ephemeroporus tridentatus and Ilyocryptus spinifer. The zooplankton biomass was very low (the maximum dry weight, observed at the peak of the rainy period in January was 62 µg.m-3). The zooplankton community was dominated by the microzooplankton, with the maximum body length below 900 µm. This assemblage was very changeable in the short term, both in numerical density and size structure, probably because of the highly variable hydrological regime of the pond.  The results from zooplankton composition, including the first record of the rotifer Microcodon clavus to Minas Gerais state and the second in Brazil, highlightedt the important role that high-elevation temporary ponds can play as aquatic biodiversity reserves. These unique ecosystems deserve greater efforts of research and monitoring, including studies of their hydrological patterns, biological diversity and adaptive mechanisms of the zooplankton community

DINÂMICA DE CIANOBACTÉRIAS EM RESERVATÓRIOS EUTRÓFICOS DO SEMI-ÁRIDO DO RIO GRANDE DO NORTE

revista vol 13 nº 2.indd The present paper reports on the temporal dynamics of phytoplankton in six eutrophic water reservoirs in Rio Grande do Norte State, Brazil, during the dry and rainy periods between September/2002 and March/2004. The eutrophication state of the reservoirs oscillated between mesotrophic and hipertrophic, thus reflecting significant variation in the nutrient composition and local biomass of algae over time. Mean depth of the reservoirs, water specific conductance, and TN/TP ratio were determinant causes for the variation of phytoplankton species. The phytoplankton community was dominated by cyanobacteria, reflecting in poor species richness and elevated biomass. Most cyanobacteria were potentially toxin-producing species, and hepatotoxin-producing blooms were recurrent. The phytoplankton was basically composed by M-group species (SR- strategists -Microcystis spp.) during the rainy period, and of an association of S1 and Sn species (R-strategists - Planktothrix and Cylindrospermopsis) during the dry period. Alternation between dominant species were also observed, which took place with associated species H, H1 S1, (R-philamentous heterocystic algae - Anabaena spp. and Aphanizomenon), K species and Lo species (C-strategists) represented by small colonies of Aphanocapsa and Snowella, however with smaller relative biomass. Elevated cyanobacterial populations and hepatotoxin-producing blooms in these water reservoirs represent a threat to human health, and controlling these blooms is strongly recommended.revista vol 13 nº 2.indd Con el objetivo de conocer la dinámica de las cianobacterias e identificar los factores que influencian esa comunidad en una región tropical semi-árida. Las colectas (n=5) fueron realizadas trimestralmente, en seis represas en Rio Grande do Norte, en la cuenca hidrográfica del rio Piranhas-Assu (04º S e 36º W), entre septiembre/2002 y marzo/2004, abarcando períodos de sequia y lluvia. El estado trófico de las represas vario entre eutrófico (en la mayor parte de los muestreos), mesotrófico e hipertrófico. La profundidad media (Zmed), conductividad eléctrica y razón TN/TP (masa) explicaron una proporción significativa de la varianza de las especies de fitoplâncton. La comunidad fitoplanctonica fue dominada por cianobacterias, con baja riqueza de especies y alta biomasa. El fitoplancton fue representado básicamente por especies de asociación M (S/R estrategas-Microcystis spp.) en el período de lluvias y asociación S1 y Sn (R estrategas - Planktotrix y Cylindrospermopsis) en el periodo de sequia. Fue también observada alternancia en la dominancia de estas especies, co-ocurriendo con especies de asociación H, H1 S1, (S R-filamentosas heterocitadas - Anabaena spp. y Aphanizomenon), K y Lo (C-estrategas), representadas por pequeñas colonias de Aphanocapsa y Snowella, con menor importancia de contribución relativa. La dominancia de cianobacterias y la presencia de floraciones hepatotóxicas como consecuencia negativa de la eutrofización representan una amenaza constante y necesita medidas de mitigación, con el objetivo de proteger la salud humana y de los recursos hídricos.Visando conhecer a dinâmica de cianobactérias e identificar os fatores que influenciam essa comunidade em região tropical semi-árida, foram realizadas coletas trimestrais (n=5) em seis reservatórios do Rio Grande do Norte, situados na bacia hidrográfica do rio Piranhas-Assu (04º S e 36º W), entre setembro/2002 a março/2004, abrangendo períodos de estiagem e chuva. O estado trófico dos reservatórios variou entre a eutrofia (na maior parte das amostragens), mesotrofia e hipereutrofia. A profundidade média (Zm), a condutividade elétrica e a razão TN/TP explicaram uma proporção significativa da variância das espécies do fitoplâncton. A comunidade fitoplanctônica foi dominada por cianobactérias, com baixa riqueza de espécies e alta biomassa. O fitoplâncton foi representado basicamente por espécies de associação M (S/R estrategistas - Microcystis spp.) no período de chuvas e associação S1 e Sn (R estrategistas - Planktotrix e Cylindrospermopsis) na estiagem. Foi também observada alternância na dominância dessas espécies, co-ocorrendo com espécies de associação H, H1 S1, (SR-filamentosas heterocitadas - Anabaena spp. e Aphanizomenon), K e Lo (C estrategistas), representadas por pequenas colônias de Aphanocapsa e Snowella, com menor importância de contribuição relativa. A dominância de cianobactérias e a presença de florações hepatotóxicas como conseqüência negativa da eutrofização representa uma ameaça constante e necessita de medidas de mitigação, visando à proteção da saúde humana e dos recursos hídricos

ZOOPLANKTON COMPOSITION IN EUTROPHIC RESERVOIRS OF THE SEMI-ARID REGION OF RIO GRANDE DO NORTE STATE (Northeast Brazil).

A composição e abundância de espécies do zooplâncton foram investigadas em seis reservatórios eutróficos do Rio Grande do Norte, caracterizados por altas concentrações de fósforo total, elevada biomassa fitoplanctônica e dominância de cianobactérias. As amostragens foram realizadas nos períodos sazonais de seca, chuva e de transição. O zooplâncton apresentou padrões quantitativos também sugestivos de condições eutróficas, com densidades elevadas. Foi constatada ainda uma diferenciação espacial na composição da comunidade. Rotíferos (destacando-se Keratella tropica, Brachionus havanensis e Keratella americana) foram dominantes na comunidade zooplanctônica dos reservatórios Itans, Passagem das Traíras e Sabugi, enquanto copépodos Calanoida (especialmente Notodiaptomus cearensis e Argyrodiaptomus sp.) dominaram os reservatórios Armando Ribeiro Gonçalves, Gargalheiras e Parelhas. Os resultados obtidos apontam para novas relações na composição da comunidade zooplanctônica em sistemas eutróficos do semi-árido tropical, incluindo a presença expressiva do zooplâncton herbívoro de grande porte como copépodos Calanoida, as quais precisam ser consideradas no estabelecimento de indicadores de condição de trofia de reservatórios.Species composition and abundance of the zooplankton were studied in six eutrophic reservoirs of Rio Grande do Norte State, which showed high concentrations of total phosphorus, high phytoplankton biomass and dominance by cianobacteria. Sampling was carried out during dry, rainy and transitional periods. Zooplankton also showed quantitative patterns suggestive of eutrophic conditions, expressed by high densities. Moreover it was observed a spatial differentiation in the composition of zooplankton community. Rotifers (specially Keratella tropica, Brachionus havanensis e Keratella americana) were the dominant forms in the zooplanktonic community of Itans, Passagem das Traíras and Sabugi reservoirs, while Calanoid copepods (mainly Notodiaptomus cearensis) dominated in Armando Ribeiro, Gargalheiras and Parelhas reservoirs. The results obtained point out to new relationships in the composition of zooplanktonic community in eutrophic reservoirs of the tropical semi-arid, including the occurrence of large-sized herbivorous zooplankton such as Calanoid copepods, which must be considered in the establishment of zooplanktonic indicators of eutrophic conditions in reservoirs

Avaliando os impactos das atividades de minera??o sobre a diversidade funcional do zoopl?ncton.

Mining activities generate countless environmental impacts, including heavy-metal contamination, sorting and increased turbidity. In aquatic ecosystems these impacts can drastically affect the initial links of the food chain, such as zooplankton. Methods: To evaluate how the different mining activities can influence the structure and functional diversity of zooplankton, we investigated the geochemical characteristics of the water and sediment in two small impoundments impacted by different mining activities (kaolin and iron extraction). We also explored zooplankton composition, species diversity and functional diversity (feeding guilds taxa). Results: As expected, the water and the sediment of both of the reservoirs showed high concentrations of trace elements, particularly Al, Ba, Fe, Mg, Mn, Sr and Zn. Zooplankton biomass and diversity were markedly reduced (< 12 ?g.DW.L-1 and H? < 1.5, respectively), and negatively correlated with turbidity and total suspended solids. Small microphages dominated the trophic composition of zooplankton, and an alternation of trophic guilds was not observed, since the dynamics of raptorial organisms was essentially linked to the temporal fluctuation of a single species of rotifer (Polyarthra cf. dolichoptera). Conclusions: In addition to changes in the aquatic habitat and zooplankton composition, the functional niches were also affected by the mining impacts. The use of the functional diversity analysis can emerge as a valuable approach to understand how zooplankton communities respond to drastic environmental changes