PhD student : Bibiana JARA VERGARA

Supervisors : Silvio Pantoja (COPAS- UDEC) and Camila Fernandez (LOMIC, SU).
Co-supervisors : Laurence Méjanelle (LECOB, SU)
Sorbonne UniversityUniversidad de Concepcion (Chile).

General information:
Farming produced 1,64 million tons of salmon and trout in 2006, 39% of which was produced in Norway and 38% in Chile. Salmon cage farming has long been known to increase local carbon inventory and nutrients while producing a drop in sedimentary O2, as well as other local negative consequences on biodiversity and the physical-chemical properties of the sea bottom. Excessive and unrestricted use of antibiotics and pesticides is also a general problem in aquaculture. Our understanding of the occurrence of toxic compounds derived from aquaculture is limited to a few reports on pyrethoids in seawater, and on florfenicol and oxytetracycline (OTC) in sediments. The objective of the present PhD thesis is to study the occurrence and persistence of aquaculture antibiotics and pesticides, currently used in salmon farms in Chile, and to evaluate their impact on key processes of the marine carbon cycle.

A first task is a distribution on seawater, suspended particles and sediments assessment of targeted antibiotics and pesticides in Puyuhuapi fjord. Partition coefficients of antibiotics and pyrethroids suggest that they should occur mainly in particulate phases except for azamethiphos that should be found mainly in the dissolved phase. The concentrations of antibiotics florfenicol and flumequine and pesticides cypermethrin and deltamethrin will be determined in particles and surface sediments collected during cruises in Canal Puyuhuapi in August 2016 and March 2017.

Another task of the present PhD will be to test whether pollutants are transferred to non target shellfish and fish resources. In order to answer this question, benthic organisms (sponges, bivalves, fish) have been sampled in Puyuhuapi Canal, in the frame of collaborations with Dr. Giovanni Daneri (CIEP), Dr. Federico Betti and Dr. Marco Bertolino (University of Pisa) and Dr. Rodrigo González (UDEC).

The last task of the present work is to understand the changes in carbon mineralization induced by continue exposure of antibiotics and pesticides. Given that aquaculture is a source of additional  organic carbon to the ecosystem, decrease in mineralization may lead to an even greater organic carbon accumulation. In order to test this hypothesis, sediments and seawater from Banyuls Bay will be exposed to pollutants used in aquaculture and the impact on mineralization and microbial community will be investigated.