Marine Life of Uruguay: Critical Update and Priorities for Future Research

Abstract

The marine areas of Uruguay consist of the Río de la Plata estuary and the adjacent shelf and slope, part of the Subtropical Convergence Ecosystem. In this paper, the main advances in the knowledge of marine life in these areas (the known) are reviewed in order to discuss future lines of research (the unknown). Information has been separately analysed for the plankton, nekton, and benthos in each of 3 areas-the littoral, the shelfs and the "open ocean". Current knowledge of marine life is uneven among the groups and areas. In the case of the plankton, research has concentrated on the near-shore waters and focused on taxonomy and distribution. Little is known about the responses of organisms to environmental variability and about biological processes. The nekton of coastal and estuarine areas is better known, but, with shelf and slope assemblages, research has focused on exploited species. The main unknowns for the nekton are how trophodynamics, reproduction, and recruitment processes are linked to environmental variability and the effect of fisheries on community structure. Littoral benthos, in particular the macroinfauna of sandy beaches, is much better studied and spatial patterns of community distribution have been identified at different scales and in relation to environmental variables. Also, at the population level, there is information about distribution, responses to disturbances, dynamics, and the roles of biotic and abiotic factors in modulating population variability. Information is mainly lacking for the sub-tidal fringe and regarding the macro-ecology of population dynamics, the dispersive abilities of larval phases, and the effects of toxic blooms on suspension feeders. Knowledge of the benthos of estuaries and more so of the shelf and slope environments is rather scarce. For the latter two, faunal inventories are far from complete. Topics identified for future research include taxonomy, macro-scale community structure and its temporal variability in relation to environmental gradients, diverse aspects of population dynamics trophodynamics and the effects of human intervention on ecosystems. The incorporation of both experimental and modelling approaches is considered important for future investigations.KEYWORDS: Marine life; Biodiversity; Río de la Plata; Atlantic Ocean, Uruguay. RESUMENLas aguas uruguayas comprenden el estuario del Río de la Plata y la plataforma y talud contiguos, parte del Ecosistema de Convergencia Subtropical. Esta contribución revisa los principales avances en el conocimiento de la vida marina en esta zona (lo conocido), para discutir futuras líneas de investigación (lo desconocido). Se analiza separadamente la información del plancton, necton y bentos de tres áreas: litoral, plataforma y ''océano profundo''. El conocimiento resulta disparejo entre grupos y entre áreas. En el plancton, la investigación se concentró en el litoral y enfocada hacia Gayana 67 (2) (2), 2003 aspectos taxonómicos y de distribución, existiendo fuertes deficiencias en el conocimiento de las r...

Impacts of two invasive mollusks, Rapana venosa (Gastropoda) and Corbicula fluminea (Bivalvia), on the food web structure of the Río de la Plata estuary and nearshore oceanic ecosystem

“…The model did not include benthic producers (e.g. macroalgae) because these are scarce in the study area, mainly due to the high turbidity of the estuary that restricts them to the shallow rocky intertidal zones (Calliari et al 2003). Data from five fishing fleets operating in the study area were used.…”

Scale-dependent patterns of macrofaunal distribution in soft-sediment intertidal habitats along a large-scale estuarine gradient

“…At the northeast side, the Uruguayan coast, with a tidal range of less than 0.3 m, is characterized by a large-scale gradient caused by the estuary flowing into the Atlantic Ocean. The gradient defines an upper region of highly turbid waters with salinity <1 ppt, and a lower region of less-turbid waters with salinity varying between 1 ppt and 30 ppt (Calliari et al 2003;Mianzan et al 2001). This pattern is related to the position of the bottom salinity front of Rı´o de la Plata, located off Montevideo and defines, at the Uruguayan coast, a west region of about 200 km of extension experiencing mostly freshwater.…”

Trophic Impacts of Marine Mammals and Seabirds in the Río de la Plata Estuary and the Nearshore Oceanic Ecosystem

“…Production/biomass ratios (P/B) and consumption/biomass ratios (Q/B) were taken from published information or obtained from the application of empirical equations using length and weight data (Christensen et al 2005). The model did not include benthic producers (e.g., macroalgae) because these are scarce in the study area due to the high turbidity of the estuary that restricts them to the shallow rocky intertidal zones (Calliari et al 2003). Data sources and diet matrix information are described in detail in the Electronic Supplementary Material.…”