Florencia Biancalana

Micro and mesozooplankton composition during winter in Ushuaia and Golondrina Bays (Beagle Channel, Argentina)

Este trabalho analisa o micro e o mesozooplâncton das Baias Ushuaia e Golondrina, constituindo a primeira pesquisa realizada nessas areas sobre estas fracoes do plâncton no inverno (agosto 2004). O numero dos taxa do microzooplâncton e do mesozooplâncton foi mais elevado na Baia Ushuaia do que na Baia Golondrina. Os ciliados aloricados foram dominantes sobre os tintinideos, enquanto que no mesozooplâncton o holoplâncton foi dominante nas duas baias. Ctenocalamus citer, Drepanopus forcipatus e Clausocalamus brevipes foram as especies mais frequentes. No meroplâncton, Halicarnus planatus e Munida gregaria foram as larvas de decapodes mais frequentes em ambos os locais. Os diferentes grupos de estacoes formados em funcao do microzooplâncton e do mesozooplânkton, e detectados na analise de agrupamento, sugerem a influencia de condicoes naturais em cada baia e de diferencas ambientais antropogenicas entre as duas baias.

Impact of a power plant cooling system on copepod and meroplankton survival (Bahía Blanca estuary, Argentina)

The impact of a power plant cooling system in the Bahia 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 findings 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.

Sewage pollution effects on mesozooplankton structure in a shallow temperate estuary

The effects of a sewage effluent with no treatment on the mesozooplankton structure and the environmental quality were evaluated in the Bahía 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.

Planktonic food and foraging of Eubalaena australis, on Peninsula Valdés (Argentina) nursery ground

Se reportan observaciones sobre alimentacion de la ballena franca austral y zooplancton disponible, realizadas en Bahia Piramides (Golfo Nuevo). Se compararon datos de plancton, comportamiento trofico de las ballenas y temperaturasalinidad y clorofila-a registrados los dias 10 y 19 de octubre de 2005. El 19/10 la biomasa zooplanctonica fue significativamente mayor, observandose un numero alto de ballenas filtrando en superficie. Esta conducta se observo desde el 17 al 21/10. El evento de forrajeo descrito, confirma que la ballena franca se alimenta en este zona reproductiva de parches de zooplancton con una adecuada composicion y alta densidad, en primavera.

Global change effects on biogeochemical processes of Argentinian estuaries: An overview of vulnerabilities and ecohydrological adaptive outlooks

The aims of this work are to provide an overview of the current stresses of estuaries in Argentina and to propose adaptation strategies from an ecohydrological approach. Several Argentinian estuaries are impacted by pollutants, derived mainly from sewage discharge and agricultural or industrial activities. Anthropogenic impacts are expected to rise with increasing human population. Climate-driven warmer temperature and hydrological changes will alter stratification, residence time, oxygen content, salinity, pollutant distribution, organism physiology and ecology, and nutrient dynamics. Good water quality is essential in enhancing estuarine ecological resilience to disturbances brought on by global change. The preservation, restoration, and creation of wetlands will help to protect the coast from erosion, increase sediment accretion rates, and improve water quality by removing excess nutrients and pollutants. The capacity of hydrologic basin ecosystems to absorb human and natural impacts can be improved through holistic management, which should consider social vulnerability in complex human-natural systems.

Mesozooplankton composition and spatial distribution, Nuevo Gulf, Patagonia, Argentina

The composition and spatial distribution of mesozooplankton of Nuevo Gulf, Argentina, were analyzed from surface samples taken on July, 1997. A total of 32 taxa were recorded. The highest abundances were found close to Nueva Bay, which is located nearby a growing urban population, whereas the lowest values were detected in the center of the gulf. Holoplankton dominated at all stations and evidenced a homogeneous spatial distribution. Meroplankton showed a more heterogeneous pattern. Ctenocalanus vanus was the most abundant taxon followed by Paracalanus parvus . Gastropoda veligers dominated the meroplanktonic fraction. Our results showed that the spatial distribution of the mesozooplankton seemed to be mainly influenced by the dominant hydrological circulation pattern of the region. This research establishes the first scientific basis for further studies in zooplankton communities of this important gulf, closely related to a natural protected worldwide known area declared a world heritage site by UNESCO.

Mesozooplankton assemblages and their relationship with environmental variables: a study case in a disturbed bay (Beagle Channel, Argentina)

This study focused on the seasonal and spatial analysis of the mesozooplankton community in a human-impacted subantarctic bay in Argentina and aimed to detect assemblages associated with environmental variability. Mesozooplankton samples and environmental data were obtained in the Ushuaia Bay (UB) seasonally, from August 2004 to June 2005, and spatially, from coastal (more polluted), middle (less influenced) and open sea water (free polluted) sampling stations. Remarkable seasonal changes on the mesozooplankton community were observed. Nitrogenated nutrients, chlorophyll a, salinity and temperature were the prevailing environmental conditions likely associated with the different mesozooplankton assemblages found in the bay. The copepods Eurytemora americana, Acartia tonsa, Podon leuckarti and Nematoda were particularly observed on the northwest coast of the bay, characterized by the highest level of urban pollution, eutrophicated by sewage and freshwater inputs from the Encerrada Bay which is connected to it. The stations situated in the northeast area, mostly influenced by freshwater input from rivers and glacier melting, showed low mesozooplankton abundances and an important contribution of adventitious plankton. The copepods Ctenocalanus citer, Clausocalanus brevipes and Drepanopus forcipatus were mostly observed at the stations located near the Beagle Channel, characterized by open sea and free polluted waters. Our findings suggest that the variations observed in the mesozooplankton assemblages in the UB seem to be modulated by environmental variables associated with the anthropogenic influence, clearly detected on the coast of the bay. Certain opportunistic species such as A. tonsa and E. americana could be postulated as potential bioindicators of water quality in subantarctic coastal ecosystems.

Variations of mesozooplankton composition in a eutrophicated semi-enclosed system (Encerrada Bay, Tierra del Fuego, Argentina)

Centro Nacional Patagonico (CENPAT-CONICET) (Bvd. Brown 2915, U9120ACD Puerto Madryn, Chubut, Argentina) *Corresponding author: biancaf@criba.edu.ar Anthropogenic eutrophication of coastal waters caused by sewage discharge and agricultural runoff is currently one of the most serious problems in the world (SMITH et al., 1999; CLOERN, 2001; TETT et al., 2003). The increase in primary productivity, which is accompanied by a deterioration of water and sediment quality, is due to nutrient and organic matter enrichment (NIXON, 1995; COSTANZO et al., 2001). The latter: i) favuors the conditions for phytoplankton bloom development, ii) increases the abundance of certain zooplankton taxa and iii) decreases zooplankton community diversity (SMITH et al., 1999; URIARTE; VILLATE, 2004; THOMPSON et al., 2007). Bio-indicator species evidencing the environmental quality of the system can be found among zooplankton. For example, species belonging to the genera Acartia and Eurytemora have been associated with areas of human disturbance (UYE et al., 1992; BIANCHI et al., 2003; CAULLEAUD et al., 2009). Encerrada Bay (EB) is located off the coast of Ushuaia city, Argentina (54o49S - 68o19W) and receives the discharge of three sewage effluents (Onas, Guarani and Beban) and Buena Esperanza stream (BES) (Fig. 1). The latter transports thaw water from Martial glacier, which is enriched with wastewater from Ushuaia city. Buena Esperanza stream has a flow range between 0.3 and 3.0 m

Heavy Metal Concentrations Found in Seston and Microplankton from an Impacted Temperate Shallow Estuary along the Southwestern Atlantic Ocean

ABSTRACT Fernández Severini, M.D.; Villagran, D.M.; Biancalana, F.; Berasategui, A.A.; Spetter, C.V.; Tartara, M.N.; Menéndez, M.C.; Guinder, V.A., and Marcovecchio, J.E., 2017. Heavy metal concentrations found in seston and microplankton from an impacted temperate shallow estuary along the southwestern Atlantic Ocean. Heavy metal concentrations (Cd, Cu, Cr, Fe, Mn, Ni, Pb, and Zn) were studied in the Bahía Blanca Estuary (BBE), one of the most anthropogenically disturbed estuaries in the SW Atlantic Ocean. This study evaluated metal concentrations in the microplankton and seston for the first time, as well as their role in the transport of contaminants in a disturbed coastal environment of the SW Atlantic. Spatial patterns of metals in suspended particulate matter (SPM; seston > 0.45 μm) and microplankton (20–200 μm) were analyzed at sampling sites located at sewage or industrial discharges and, also far from this area, during warm months in 2012 and 2013. Dissolved inorganic nutrients, particulate organic matter (POM), and chlorophyll a (Chl-a) were also analyzed. The POM and Chl-a concentrations were higher near to the sewage discharges; however, metals showed different concentrations between sampling site stations. Those located far from human disturbances showed similar levels to the sites at the sewage or industrial discharges in some cases. In general, the SPM had higher concentrations of metals than the microplankton. In particular, Cr presented important levels in this fraction, which was potentially associated with industrial discharges. On the other hand, a contrasting partition was found for Pb, Zn, and Cu that exhibited higher levels in the microplankton-net material. The high levels of Pb in the microplankton of the BBE may indicate a high availability of this metal in the environment and high uptake rates, with potential health risks to humans and marine life attributable to its toxic effects.

Reproductive trade-off of the copepod Acartia tonsa in a hypersaline estuary of the Southwestern Atlantic. Temporal variations in the morphology of eggs

ABSTRACT The purpose of the present work was to study the seasonal variations in egg production, morphology and hatching success in the cryptic species Acartia tonsa, taking into account variations in female size, population abundance and environmental factors in a turbid and hypersaline estuary. Sampling was performed during the austral warm (18–23°C and 32–36 salinity) and cold seasons (5–7°C; 32–38) in Bahía Blanca Estuary (BBE), Argentina, during 2007 and 2009. Field-collected females were incubated in the laboratory simulating in situ environmental conditions, and specimens from fixed samples were measured using optical and scanning electronic microscopy. Acartia tonsa’s marked seasonality in its reproductive traits was found to ensure its permanence in the water column all over the year. During the warm season, small-sized females were observed to invest their energy in the production of subitaneous eggs with high hatching success and smooth appearance (12.95 ± 2.38 eggs f−1 day−1 and specific egg production rate (SEP) of 16.57%C f−1 day−1). During the cold season, females invested C in body mass as well as in the production of resting eggs of three different morphotypes (6.56 ± 3.2 eggs f−1 day−1 and SEP of 7.37%C f−1 day−1). Although these morphotypes were found to show differences in surface ornamentation, they exhibited the same delayed hatching behaviour. The eggs with shorter spines were found to integrate the resting egg bank in BBE. Our findings confirming a delayed egg hatching behaviour and a great tolerance to low temperatures and high salinities in the A. tonsa population in BBE suggest that this possible strain is a valuable phenotype for aquaculture.