INVESTIGADORES
COLLINS Pablo Agustin
congresos y reuniones científicas
Título:
Biology and ecology of freshwater decapods of southern South America
Autor/es:
COLLINS P.; WILLINER V.; GIRI F.
Lugar:
Franckfurt
Reunión:
Conferencia; 21 st International Senckenberg Conference. Biology of Freshwater decapods; 2010
Institución organizadora:
Senckenberger Museum
Resumen:
The decapod fauna in southern of South America (Atlantic slope) is characterized by species of five families (Sergestidae, Palaemonidae, Parastacidae, Aeglidae, Trichodactylidae). Some species, genus and/or family are endemics, showing a strengthen relation with geo-climatic history of the continent and their hydrography. The diversity, and species distribution is the product of million years of evolution, together to the strong relation of different geological and hydrologicals events that occurs in South America. Instability is a constant in this land, frostbite, heat, flooding, drought, low and high salt concentration, pH change are any of the conditions that governed the different systems. The aim of this presentation is show a synthesis of the works about the biology and ecology of continental decapods in this region of the world. Prawns live in ponds and rivers associated to aquatic vegetation or benthos community, crabs below rock, in cave, bottom and vegetation, pseudo-crabs below rock and crayfish in cave or below rock. In different works, we discuss the growth and their relation with abiotic factors, due to some species of prawns that have populations that live in environment in where the conductivity oscillates between 20.5 and 5600 uhms/cm2 (e.g. Ibera, Salado River), temperature oscillates between 1 to 44 °C (mountain rivers, rivers with floodplain), the pH between 6.1 to 8.25 and the dissolved oxygen vary between 2 to 12 mg/l. The osmoregulation is a principal factor that permits that the individuals can inhabit these systems, and more become independent of osmotic relation. Some species of crabs made cave to live and maintain the humidity when the rivers or ponds are drought during a time of the year. We observed that the reproduction have any similarities in all groups, the seasonality of the events, diminution of egg number, the eclosion in late stage are some. Moreover, the parental care or relation between juvenile and mother during a time occur in brachiurans, and anomurans. Another theme is the interaction into the systems, directing the matter cycle and energy flux to different communities that characterize the freshwater environments. The feeding activities vary with the different rhythms that govern the ecosystems. This causes that occurs qualitative and quantitative changes in the food chains. The decapod crustaceans are important and interesting group, for their high density and nutritional quality, to know the trophic webs as intermediaries in the aquatic environments. The dynamics of decapods in the web is regulated by the rhythms of exogenous factors such as abiotic (e.g. flood pulse, temperature, seasonality, light hours, conductivity, pH) and biotic parameters (presence of predators, competition, offers trophic). Moreover, the activities are coupled to endogenous rhythms of each species (e.g. molting, reproduction, nutrition requirement). All these rhythms that influence trophic relationships correspond to the evolutionary interaction for many years between environment and species. Freshwater prawns and crabs are considered to be not only predators but also preys, being important elements in the food chain. These crustaceans take part in the matter-energy exchange between aquatic and terrestrial systems. The information obtained show that the hidrological regime, and the connectivity degree among different environments influence the refuge and food availability modified the intra and interspecific relationships.