Abstract

Bahía Salado, located in the middle of the Atacama Desert, is a habitat of high ecological value, particularly because of the presence of sea turtles (Chelonia mydas) and seagrasses. This bay also plays an important economic role for the Atacama Region, since it supports the economy of local coastal communities based on fisheries and algae extraction. Although, Bahía Salado has an ecological and economical relevance, almost none information exists on the biological components of this ecosystem. Furthermore, little is known about Chilean feeding grounds for eastern Pacific green turtles, to which knowledge we contribute in the study presented herein. Between 2013 and 2015, we conducted seasonal monitoring of the local green turtle aggregation, where population and health parameters were determined (blood parameters, heavy metals determination and genetic analysis; n=7). Likewise, we performed a bathymetric and benthic macroinfauna characterization of the study area. Our results indicate that blood values of these turtles follow standard parameters. However, copper and lead concentrations show the highest values described for all sea turtles species around the world (2.259 µg/g and 1.105 µg/g, respectively). Additionally, analysis of 773 base pairs (bp) sequences of the mitochondrial control region indicate that Galápagos nesting stock is the principal source stock to this aggregation (43% carried haplotype CmP-4.6, 29% CmP-4.7, 14% CmP-4.1 and 14% CmP-15.1). Bahía Salado is a shallow bay (up to 8 m deep) characterized by a mixture of hard and soft substrates, with a high coverage of seagrass (Zostera chilensis) algae and invertebrates, on which these turtles most likely feed. In addition, our results show that Z. chilensis constitutes a key matrix for this ecosystem productivity and sustainability, harboring an important diversity of organisms in early onthogenic life stages (e.g. Tagelus dombeii, Argopecten sp, Fissurella sp. and Cancer sp). Our research on the southernmost feeding ground for eastern Pacific green turtles reinforces the high adaptability that this species exhibit in the dynamic Southeast Pacific. This work, also contributes to a better understanding of regional populations ecology and health status. Moreover, green turtles seem to play a key role in local ecosystem maintenance, which productivity and conservation is crucial as much for human sustainable development as for marine organisms survival.