27 research outputs found

    Size-fractionated chitin contribution to seston, with linkages to the copepod acartia

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    The main purpose of the present work was to determine chitin from experimental size-fractioned incubations of the copepod Acartia tonsa, considered one of the primary sources of chitin in the Bahía Blanca Estuary. Sampling was performed during the austral warm season at one station in 2014 and 2015. Field-collected females (200 individuals) and males (100 individuals) were incubated in 8 L containers in the laboratory simulating in situ environmental conditions of temperature and salinity for 72 hours. Chitin content was measured in different size fractions (20-60, 60-135 and ≥135 μm). Particulate organic matter and dry weight were also determined in the different size fractions. Highly agglutinated debris, pellets, and natural food (diatoms and tintinnids) were observed in the 20-60 μm size fraction, with a maximum of 0.68±0.21mg L-1 chitin, and the highest contribution of chitin to POC (34.62±18.50 %). Eggs, nauplii and natural food (diatoms and tintinnids) were observed in the 60-135 μm size fraction, with a maximum of 0.20±0.12 mg L-1 chitin and a contribution to POC of 9.80±5.00 %. Acartia adults and their exuviae were observed in the ≥135 μm size fraction, with a maximum concentration of chitin of 0.67±0.40, and a maximum contribution of chitin to POC TS of 30.47±27.23 %. Differences were detected between the different fractions in chitin, POC and DW, indicating that the 20-60 and ≥135 µm size fractions were both an important contribution of chitin in the experiment. Our results suggest that pellets, carcasses and exuviae along with natural food and organic aggregates were the main source of chitin in this system.Fil: Biancalana, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin

    Morphological types and seasonal variation in eggs of zooplankton species from bottom sediments in Bahia Blanca Estuary, Argentina

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    Resting egg production is a survival mechanism in zooplankton species against adverse environmental conditions. Egg accumulation in the upper layer of the bottom sediments is fundamental to the resurgence of the populations of these species when conditions become more favourable. Rotifers, such as Synchaeta sp. and planktonic copepods such as Acartia tonsa and Eurytemora americana are commonly found in Bahía Blanca Estuary and they produce resting eggs. We studied eggs isolated from samples of bottom sediments obtained from two sites located within the inner part of Bahía Blanca Estuary (Cuatreros Port and Ing. White Port). The aims of our work were to describe the morphological types of eggs found in bottom sediments; to try to identify to which species they belong; to corroborate the identity of some of them by means of incubations; and to determine either the spatial or seasonal presence of morphological types according to the sampling site. Sediment samples were collected from Cuatreros Port on a monthly basis from January to December 2003 and samples from Ing. White Port were collected from the area close to the industrial zone only in April 2004. All samples were treated following the sugar flotation method of Onbé. The eggs were observed under stereomicroscope and light microscope. Besides, incubation experiments with eggs were sometimes carried out. Five morphological types of eggs (type A, B, C, D and E) were found in the sediments from Cuatreros Port whereas three types of eggs were found at Ing. White Port (F, G and H). Of the 8 morphological types of eggs found in this study, only those of the rotifer Synchaeta sp. in Cuatreros Port and the copepod A. tonsa in the two sampling sites were confirmed to be respectively diapausal and “delayed -hatching”. As regards the seasonal variation of the eggs found in the sediments from Cuatreros Port and the active forms of the populations of Synchaeta sp. and A. tonsa, our study confirms the presence of eggs in the sediment either in periods of time during which no active forms have been previously reported in the plankton or in periods of time during which only some active forms have been reported at very low densities. Concerning the spatial variation at Ing.White Port, the differences in the presence of eggs across the sampling areas may be due to sediment modifications produced by anthropic impact, where industrial effluents are discharged.Fil: Diodato, Soledad Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Hoffmeyer, Monica Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Tecnológica Nacional; Argentin

    Tidal effects on short-term mesozooplankton distribution in small channels of a temperate-turbid estuary, Southwestern Atlantic

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    The short-term variability of mesozooplanktondistribution and physicochemical variables wasexamined in two different channels of the BahíaBlanca Estuary, Argentina, during two tidalcycles. All the physicochemical measurementsand mesozooplankton sampling were performedat a fixed site during approximately 22-23 h at3-h intervals. Pumps were used to obtain surfaceand bottom mesozooplankton samples and thewater speed of each stratum was measured withan Acoustic Doppler Current Profiler (ADCP). Inall, 23 mesozooplanktonic taxa belonging to fourphyla (Arthropoda, Annelida, Echinodermata andChordata) were identified. The most abundant taxaduring the two tidal cycles were Balanus glandulalarvae, Eurytemora americana and Acartia tonsa.A discernible variability in the water conditionsand vertical mesozooplankton distribution (VMD)different from that known for the estuary´s mainchannel, was found in the other two selectedchannels. VMD varied during the tidal cycle inboth channels in accordance with the channel?sgeomorphology and water dynamic characteristicsof each of them. The variation of the abundance ofthe different taxa during ebb and flood currents mightindicate the existence of a tidal vertical migrationof the mesozooplankton as a response to particulardynamic water conditions.A variação de curto prazo da distribuição do mesozooplâncton e das variáveis físico-químicas foi examinada em dois diferentes canais do Estuário de Bahia Blanca, Argentina, durante dois ciclos de maré. As medidas físico-químicas e a amostragem do zooplâncton foram realizadas em dois locais fixos durante aproximadamente 22-23 horas, com intervalos de 3 horas. Bombas foram utilizadas para obter amostras de zooplâncton na superfície e no fundo e a velocidade da água em cada estrato foi medida com o Perfilador Acústico de Corrente (ADCP). Ao todo, foram identificados 23 taxa mesozooplanctônicos pertencentes a 4 filos (Arthropoda, Annelida, Echinodermata e Chordata). Os grupos mais abundantes durante os dois ciclos de maré foram larvas de Balanus glandula, além de Eurytemora americana e Acartia tonsa. Nos dois canais selecionados foi identificada uma variação nas condições da água e na distribuição vertical do mesozooplâncton (DVZ) diferente daquela conhecida para o canal principal do estuário. DVZ variou durante o ciclo de maré em ambos os canais de acordo com a geomorfologia e características da dinâmica das águas existente em cada um deles. A variação na abundância dos diferentes taxa durante as marés vazante e enchente poderia estar indicando a existência de migração vertical do mesozooplâncton em resposta a uma determinada condição dinâmica da água.Fil: Chazarretta, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); ArgentinaFil: Hoffmeyer, Monica Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); ArgentinaFil: Cuadrado, Diana Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); ArgentinaFil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); Argentin

    Harpacticoida (Copepoda) in the plankton of Ushuaia and Golondrina Bays, Beagle Channel, Argentina

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    Harpacticoid copepods form a diverse and abundant group of the meiofauna in marine benthic habitats. Moreover, harpacticoids are frequently found in planktonic samples particularly in shallow and algae-covered coastal waters. Despite their high abundance, little is known about their taxonomy and importance as a component of the food web in the Southern bays of Argentina. Mesozooplankton samples and environmental data were obtained seasonally from Ushuaia and Golondrina Bays (August 2004 to June 2005) and analyzed for the composition and abundance of harpacticoid copepods. Remarkable seasonal changes in the harpacticoid communities were observed. In Ushuaia Bay, nitrogenated nutrients, chlorophyll a, salinity, and temperature were the prevailing environmental parameters that influenced the harpacticoid community, giving rise to different harpacticoid assemblages. The results highlight the importance of the community of Harpacticoida in both bays and provide background data for further studies on zooplankton communities and monitoring programs in marine systems.Fil: Biancalana, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Veit Köhler, G.. German Centre for Integrative Biodiversity Research; AlemaniaFil: Fricke, Anna Lena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Leibniz Centre for Tropical Marine Research; AlemaniaFil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin

    Micro- and mesozooplankton successions in an Antarctic coastal environment during a warm year

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    The rapid increase in atmospheric temperature detected in the last decades in the Western Antarctic Peninsula was accompanied by a strong glacier retreat and an increase in production of melting water, as well as changes in the sea-ice dynamic. The objective of this study was to analyze the succession of micro- and mesozooplankton during a warm annual cycle (December 2010-December 2011) in an Antarctic coastal environment (Potter Cove). The biomass of zooplankton body size classes was used to predict predator-prey size relationships (i.e., to test bottom-up/top-down control effects) using a Multiple Linear Regression Analysis. The micro- and mesozooplanktonic successions were graphically analyzed to detect the influence of environmental periods (defined by the degree of glacial melting, sea-ice freezing and sea-ice melting) on coupling/uncoupling planktonic biomass curves associated to possible predator-prey size relationship scenarios. At the beginning of the glacial melting, medium and large mesozooplankton (calanoid copepods, Euphausia superba, and Salpa thompsoni) exert a top-down control on Chl-a and microzooplankton. Stratification of the water column benefitted the availability of adequate food-size (Chl-a <20) for large microzooplankton (tintinnids) development observed during fall. High abundance of omnivores mesozooplankton (Oithona similis and furcilia of E. superba) during sea-ice freezing periods would be due to the presence of available heterotrophic food under or within the sea ice. Finally, the increase in microzooplankton abundance in the middle of spring, when sea-ice melting starts, corresponded to small and medium dinoflagellates and ciliates species, which were possibly part of the biota of sea ice. If glacier retreat continues and the duration and thickness of the sea ice layer fluctuates as predicted by climate models, our results predict a future scenario regarding the zooplankton succession in Antarctic coastal environments.Fil: Garcia, Maximiliano Darío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Dutto, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Chazarreta, Carlo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Schloss, Irene Ruth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología Costera; Argentina. Universidad Nacional de Tierra del Fuego; ArgentinaFil: Hoffmeyer, Monica Susana. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Universidad Tecnológica Nacional. Facultad Regional Bahía Blanca; Argentin

    Impacto del sistema de enfriamiento de una central termoeléctrica sobre la supervivencia de copépodos y meroplancton (estuario de Bahía Blanca, Argentina)

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    The impact of a power plant cooling system in the Bahía Blanca estuary (Argentina) on the survival of target zooplanktonic organisms (copepods and crustacean larvae) and on overall mesozooplankton abundance was evaluated over time. Mortality rates were calculated for juveniles and adults of four key species in the estuary: Acartia tonsa Dana, 1849 and Eurytemora americana Williams, 1906 (native and invading copepods), and larvae of the crab Chasmagnathus granulata Dana, 1851 and the invading cirriped Balanus glandula Darwin, 1854. Mean total mortality values were up to four times higher at the water discharge site than at intake, though for all four species, significant differences were only registered in post-capture mortality. The findin gs show no evidence of greater larval sensitivity. As expected, the sharpest decrease in overall mesozooplankton abundance was found in areas close to heated water discharge.El impacto del sistema de enfriamiento de una planta termoeléctrica ubicada en el estuario de Bahía Blanca, Argentina, fue evaluado en el tiempo, sobre la supervivencia de especies zooplanctónica s seleccionadas (copépodos y larvas de crustáceos) y la abundancia general del meso-zooplancton. Se calcularon tasas de mortalid ad de juveniles y adultos de cuatro especies clave en el estuario: Acartia tonsa Dana,1849 y Eurytemora americana Williams,1906 (copépodos nativo e invasor), y larvas del cangrejo Chasmagnathus granulata Dana, 1851 y del cirripedio invasor Balanus glandula Darwin, 1854. Los valores medios hallados de la tasa de mortalidad total, fueron hasta cuatro veces más altos en la descarga q ue en el agua de entrada al sistema. Sin embargo sólo se registraron diferencias significativas entre estos dos sitios, en los valores de mortalidad post-captura obtenidos para las cuatro especies. Los resultados del estudio no demostraron una mayor sensibilidad larval. Como se esperaba, la disminución más pronunciada en la abundancia general del meso-zooplancton fue observada en la zona del estuario cercana de la descarga de agua sobrecalentada.Fil: Hoffmeyer, Monica Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Biancalana, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin

    Seasonal occurrence and hatching success of benthic eggs of calanoid copepods in the BahĂ­a Blanca Estuary, Argentina

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    The seasonal abundance and hatching success of calanoid benthic eggs were examined during the coexistence of Acartia tonsa and Eurytemora americana in the Bahía Blanca Estuary (BBE). The dormancy behaviour of eggs extracted from surface sediment layers was tested by simulating seasonal conditions during incubation. There was a greater abundance of benthic eggs of E. americana (≤8.68×106 eggs m-2) than of A. tonsa, the latter consistently showing low egg abundance (≤0.8×106 eggs m-2). The emergence of most E. americana nauplii occurred at 17°C after the experimental warming phase (refractory phase of 280 days), confirming the diapause character of these eggs. The emergence of the first A. tonsa nauplii from initial cold season samples occurred at 9-12°C after 60-70 days of incubation. However, a 180-day delay in hatching at temperatures ≥15°C was also observed in A. tonsa eggs from the last sampling days of the cold season, thus suggesting an intermediate behaviour between diapause and quiescence. The benthic egg bank in the inner zone of the BBE provides a temporary reservoir for both key copepods, thus contributing in their survival.Fil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Dutto, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Chazarreta, Carlo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Hoffmeyer, Monica Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Tecnológica Nacional. Facultad Regional Bahía Blanca; Argentin

    Environmental regulation of the estuarine copepods Acartia tonsa and Eurytemora americana during coexistence period

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    The seasonal dynamics of Acartia tonsa and the invader Eurytemora americana were analysed in relation to the environ- mental variability occurring from April to November in the Bahia Rlanca Estuary. Twice a month, the abundance of eggs, nauplii, copepodites and adults was examined and some environmental variables were recorded. Multivariate statistics (CCA) was applied to analyse the data of variables. Acartia tonsa eggs and nauplii diminishedfrom April-May and they were almost absent between Tune and September, although a small larval peak cot~ld be detected from the end of July to October. All the stages of this species increased in number through spring. Eurytemora americana was registered as from June and only nauplii larvae were observed, with a peak increase during September. Copepodites and adults were observed as from July, increasing in number until peaking at the end ofSeptember. The number of all stages of this species decreased abruptly, the whole population disappearing from the plankton. The A. tonsa developmental stages were most positively correlated with temperature, photoperiod and other light variables whereas those of E. americana showedpositive correlations with chlorophyll-a and salinity. The gradients ofthe main environmental factors likelygive rise to a certain niche separation facilitating the coexistence of the two copepod populations within the period studied.Fil: Hoffmeyer, Monica Susana. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto Argentino de OceanografĂ­a. Universidad Nacional del Sur. Instituto Argentino de OceanografĂ­a; Argentina. Universidad TecnolĂłgica Nacional; ArgentinaFil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto Argentino de OceanografĂ­a. Universidad Nacional del Sur. Instituto Argentino de OceanografĂ­a; ArgentinaFil: Beigt, Debora. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto Argentino de OceanografĂ­a. Universidad Nacional del Sur. Instituto Argentino de OceanografĂ­a; ArgentinaFil: Piccolo, Maria Cintia. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto Argentino de OceanografĂ­a. Universidad Nacional del Sur. Instituto Argentino de OceanografĂ­a; Argentina. Universidad Nacional del Sur; Argentin

    Seasonal variation in the egg morphology of the copepod Eurytemora americana and its relationship with reproductive strategy in a temperate estuary in Argentina

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    Seasonal variation in the morphology of Eurytemora americana eggs and its relationship with reproductive strategy were studied in the Bahía Blanca Estuary. Eggs from field females were analysed morphologically by optical (OM) and electron microscopy [scanning electron microscopy (SEM)–transmission electron microscopy (TEM)] during the population pulse. Additionally, egg-carrying females were incubated simulating in situ environmental conditions to evaluate the resting egg character. Subitaneous and resting eggs were indistinguishable by OM, but showed different chorion appearance under SEM and TEM. Sinuous patterned chorion eggs, mainly produced during the period of population growth, were classed as subitaneous eggs based on their high level of  hatching success. Eggs with a sponge-like appearance, produced after the population peaked,  were classed as diapause eggs based on their inability to hatch even under favourable conditions. There were significant differences in egg size through the population pulse and diapause eggs were significantly bigger than subitaneous eggs. The observation of both morphotypes in egg-carrying females after peak population abundance confirms the existence of a transitional reproductive stage before the exclusive production of diapause eggs at the end of the pulse. Diapause egg production enables E. americana to resist adverse conditions, ensuring its survival in temperate estuaries.Fil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Hoffmeyer, Monica Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Dutto, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Biancalana, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin

    Sewage pollution effects on mesozooplankton structure in a shallow temperate estuary

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    The effects of a sewage effluent with no treatment on the mesozooplankton structure and the environmental quality were evaluated in the BahĂ­a Blanca Estuary, during June to November 1995. The highest values of particulate organic matter, nutrients and specially phosphate, were observed in the effluent discharge zone. In addition, taxa richness, mesozooplankton abundance and Shannon diversity values were lower in the sewage discharge area compared with the less polluted area. Eurytemora americana and Acartia tonsa as well as larvae of Balanus glandula, Neohelice granulata and Spionidae were found in the discharge area with lower densities. These results highlight the importance of sewage effluent effects on mesozooplankton community providing background data to use in other monitoring programmes.Fil: Biancalana, Florencia. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto Argentino de OceanografĂ­a. Universidad Nacional del Sur. Instituto Argentino de OceanografĂ­a; ArgentinaFil: Menendez, Maria Clara. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto Argentino de OceanografĂ­a. Universidad Nacional del Sur. Instituto Argentino de OceanografĂ­a; ArgentinaFil: Berasategui, Anabela Anhi. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto Argentino de OceanografĂ­a. Universidad Nacional del Sur. Instituto Argentino de OceanografĂ­a; ArgentinaFil: Fernandez Severini, Melisa Daiana. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto Argentino de OceanografĂ­a. Universidad Nacional del Sur. Instituto Argentino de OceanografĂ­a; ArgentinaFil: Hoffmeyer, Monica Susana. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca. Instituto Argentino de OceanografĂ­a. Universidad Nacional del Sur. Instituto Argentino de OceanografĂ­a; Argentin
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