title: Ecophysiological responses of juvenile seabass (Dicentrarchus labrax) exposed to increased temperature and dietary methylmercury.
abstract: The ecotoxicological effects of methylmercury (MeHg) exposure have been intensively described in literature. Yet, it is still unclear how marine biota will respond to the presence of MeHg under climate change, namely ocean warming. The present study aimed to investigate, for the first time, fish condition [Fulton's K index (K), hepatosomatic index (HIS) and brain-to-body mass ratio (BB-ratio)] and several stress-related responses in an ecologically and commercially important fish species (Dicentrachus labrax) exposed for 28days to dietary MeHg (8.0mg kg-1 dw) and temperature increase (+4°C). Results showed significant impairments on fish condition, i.e. up to 34% decrease on K, >100% increase on HIS and 44% decrease on BB-ratio, compared to control conditions. Significant changes on tissue biochemical responses were observed in fish exposed to both stressors, acting alone or combined, evidencing the relevance of assessing possible interactions between different environmental stressors in ecotoxicological studies. For instance, muscle showed to be the least affected tissue, only revealing significant alterations in GST activity of MeHg-enriched fish. On the other hand, liver exhibited a significant induction of GST (>100%) and CAT (up to 74%) in MeHg-enriched fish, regardless of temperature exposure, as well as decreased SOD activity (19%) and increased HSP70/HSC70 content (87%) in fish exposed to warming alone. Brain showed to be affected by temperature (69% of GST inhibition and >100% of increased CAT activity), MeHg (>100% of increased CAT activity, 47% of SOD inhibition and 55% of AChE inhibition), as well as by the combination of both (GST, SOD and AChE inhibition, 17%, 48% and 53%, respectively). Hence, our data provides evidences that the toxicological aspects of MeHg ca be potentiated by warmer temperatures, thus, evidencing the need for further research combining contaminants exposure and climate change effects, to better forecast ecological impacts in the ocean of tomorrow.
authors.affiliation: Division of Aquaculture and Seafood Upgrading. Portuguese Institute for the Sea and Atmosphere, I.P. (IPMA), Rua Alfredo Magalhães Ramalho, 6, 1495-006 Lisboa, Portugal; Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal; MARE - Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal. Electronic address: aluisa@ipma.pt.
authors.forename: Ana Luísa
authors.initials: AL
authors.lastname: Maulvault
authors.affiliation: Division of Aquaculture and Seafood Upgrading. Portuguese Institute for the Sea and Atmosphere, I.P. (IPMA), Rua Alfredo Magalhães Ramalho, 6, 1495-006 Lisboa, Portugal.
authors.forename: Vera
authors.initials: V
authors.lastname: Barbosa
authors.affiliation: Division of Aquaculture and Seafood Upgrading. Portuguese Institute for the Sea and Atmosphere, I.P. (IPMA), Rua Alfredo Magalhães Ramalho, 6, 1495-006 Lisboa, Portugal.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Alves
authors.affiliation: Division of Aquaculture and Seafood Upgrading. Portuguese Institute for the Sea and Atmosphere, I.P. (IPMA), Rua Alfredo Magalhães Ramalho, 6, 1495-006 Lisboa, Portugal; Instituto Superior de Agronomia (ISA), School of Agriculture, University of Lisbon, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Custódio
authors.affiliation: Division of Aquaculture and Seafood Upgrading. Portuguese Institute for the Sea and Atmosphere, I.P. (IPMA), Rua Alfredo Magalhães Ramalho, 6, 1495-006 Lisboa, Portugal; Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal; MARE - Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Anacleto
authors.affiliation: MARE - Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal.
authors.forename: Tiago
authors.initials: T
authors.lastname: Repolho
authors.affiliation: Division of Aquaculture and Seafood Upgrading. Portuguese Institute for the Sea and Atmosphere, I.P. (IPMA), Rua Alfredo Magalhães Ramalho, 6, 1495-006 Lisboa, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Pousão Ferreira
authors.affiliation: MARE - Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal.
authors.forename: Rui
authors.initials: R
authors.lastname: Rosa
authors.affiliation: Division of Aquaculture and Seafood Upgrading. Portuguese Institute for the Sea and Atmosphere, I.P. (IPMA), Rua Alfredo Magalhães Ramalho, 6, 1495-006 Lisboa, Portugal; Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Marques
authors.affiliation: UCIBIO, REQUIMTE Chemistry Department, Centre of Fine Chemistry and Biotechnology, Faculty of Sciences and Technology, Nova University of Lisbon (CQFB-FCT/UNL), 2829-516 Caparica, Portugal.
authors.forename: Mário
authors.initials: M
authors.lastname: Diniz
mesh_terms: D000818:Animals; D001492:Bass / Q000502:physiology*; D057231:Climate Change; D008767:Methylmercury Compounds / Q000009:adverse effects*; D012623:Seawater / Q000737:chemistry; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000009:adverse effects*
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical
keywords: Animal condition; Dietary MeHg; Heat shock; Neurotoxicity; Oxidative stress; Seawater warming