Seasonal variation and influence of turbidity and salinity on the zooplankton of a saline lake in central Argentina

Abstract

ABSTRACT. The limnology of saline water bodies at other latitudes is fairly well known, but in Argentina such studies have only recently begun. The applicability of many conclusions regarding the functioning of these environments around the world is limited due to the scant ecological knowledge of some endemic species recorded in the assemblages of Argentine lakes. The aims of this work were to determine the effects of salinity and inorganic turbidity on the taxonomic composition, abundance, and zooplankton biomass in a shallow, hypereutrophic, mesosaline lake in the north of La Pampa province characterized by seasonality, variations in level and salinity, and the lack of macrophytes and fishes, and to compare it with other shallow lakes of the province. We found important differences with other saline lakes: the species richness was lower; the mean abundance of zooplankton was between four and six times higher; and rotifers, which were not affected by salinity or the concentration of inorganic suspended solids, were numerically predominant. Crustaceans, on the other hand, were negatively affected by these environmental factors. Biomass was twofold higher than that recorded in the same period in two shallow lakes of Pampa, with similar nutrient concentrations but lower salinities. Keywords: saline lakes, inorganic turbidity, zooplankton biomass, Boeckella poopoensis, Argentina.Variación estacional e influencia de la turbidez y la salinidad sobre el zooplancton de un lago salino de la región central de Argentina RESUMEN. La limnología de los cuerpos de agua salinos de otras latitudes es bastante conocida, pero en Argentina se ha comenzado a estudiar recientemente. Muchas conclusiones sobre el funcionamiento de estos ambientes a nivel mundial son de aplicación restringida debido a que las asociaciones registradas en los lagos argentinos tienen algunas especies endémicas, cuyo conocimiento ecológico es escaso. Los objetivos de este trabajo fueron determinar los efectos de la salinidad y la turbidez inorgánica sobre la composición taxonómica, abundancia y biomasa zooplanctónica en un lago somero mesosalino hipereutrófico del norte de La Pampa, caracterizado por su temporalidad, variaciones del nivel y salinidad, carencia de macrófitas y peces, y compararlo con otros lagos someros de la provincia. Se encontraron importantes diferencias con otros lagos salinos, la riqueza específica fue menor, la abundancia media del zooplancton fue entre 4 a 6 veces superior y el predominio numérico fue de los rotíferos, que no fueron afectados por la salinidad o la concentración de sólidos suspendidos inorgánicos, a diferencia de los crustáceos, que fueron afectados negativamente por estos factores ambientales. La biomasa fue dos veces más elevada que la registrada en el mismo período en dos lagos someros pampeanos con parecida concentración de nutrientes pero con salinidades menores.

Biology of Boeckella poopoensis Marsh, 1906 (Copepoda, Calanoida) in natural conditions in temporary saline lakes of the central Argentina

“…Throughout the study, the halophilic (De los Ríos & Crespo 2004) and eurihaline character of B. poopoensis (Echaniz & Vignatti 2011, Echaniz et al 2013) was evidenced, since it was recorded in a relatively wide range of salinities. The species was always present in three lakes (Cha, SJ and Ut), but was recorded only from October in EC.…”

AVALIAÇÃO DAS CONDIÇÕES AMBIENTAIS DO ESTUÁRIO DO RIO CARRAPICHO (Itamaracá-PE): BIOMASSA FITOPLANCTÔNICA E HIDROLOGIA

“…Este padrão também foi observado na Barra de Orange e Catuama por Figueiredo et al (2006); no mesmo rio estudado, por ; no Lago Salino Central, por Echaniz (2011). Observou-se que nas preamares, mesmo no período de maior pluviosidade, os índices de chuvas não foram suficientes para modificar de forma brusca a salinidade.…”

Distribution and biological aspects of the introduced speciesMoina macrocopa (Straus, 1820) (Crustacea, Cladocera) in the semi-arid central region of Argentina

“…These activities are reflected in the high content of nutrients contributed by the fertilization of crops as well as by the feces and urine of cattle raised in the surrounding area. This is enhanced by the arheic character of the basins, which favors the concentration of nutrients both in water and in sediment (Echaniz et al 2009, 2010, Echaniz & Vignatti 2011. Goulden (1968) reported a maximum size of 1.5 mm for parthenogenetic females, but some specimens of the Pampean lakes, as well as some from Corrientes (Paggi 1997) and Rio de Janeiro, exceed this size (Elmoor-Loureiro et al 2010) (1.19 mm and 1.08 mm, respectively).…”

“…In the province of La Pampa, in the semi-arid central region of Argentina, although more than 100 water bodies have been surveyed since 1992, M. macrocopa was first recorded in December 1999, in a sub-saline shallow temporary lake (Bajo de La Tigra) and subsequently in other five water bodies (Echaniz et al 2005, Echaniz & Vignatti 2011, being last recorded in February 2007. Although its presence was reported, no specific information was provided.…”