Assessing estuarine quality: A cost-effective in situ assay with amphipods

In situ assays based on feeding depression can be powerful ecotoxicological tools that can link physiological organism-level responses to population and/or community-level effects. Amphipods are traditional target species for toxicity tests due to their high sensitivity to contaminants, availability in the field and ease of handling. However, cost-effective in situ assays based on feeding depression are not yet available for amphipods that inhabit estuarine ecosystems. The aim of this work was to assess a short-term in situ assay based on postexposure feeding rates on easily quantifiable food items with an estuarine amphipod. Experiments were carried out under laboratory conditions using juvenile Echinogammarus marinus as the target individual. When 60 Artemia franciscana nauplii (as prey) were provided per individual for a period of 30 min in dark conditions, feeding rates could be easily quantified. As an endpoint, postexposure feeding inhibition in E. marinus was more sensitive to cadmium contamination than mortality. Assay calibration under field conditions demonstrated the relevance of sediment particle size in explaining individual feeding rates in uncontaminated water bodies. An evaluation of the 48-h in situ bioassay based on postexposure feeding rates indicated that it is able to discriminate between unpolluted and polluted estuarine sites. Using the harmonized protocol described here, the in situ postexposure feeding assay with E. marinus was found to be a potentially useful, cost-effective tool for assessing estuarine sediment and water quality.This research was partially funded by the 7th Framework Programme (FP7 2007-2013) of the European Commission through a Marie Curie Intra-European Fellowship for Career Development (PIEF-GA-2011-299747). MMH was supported by a postdoctoral contract funded by the Junta de Comunidades de Castilla-La Mancha (POST 2014/7780). Currently, MMH holds a Juan de la Cierva research contract awarded by the Spanish Ministry of Science and Innovation-European Social Fund (IJCI-2014-20171), and AJPC a predoctoral grant funded by the Portuguese FCT, the European Social Fund and POPH programme (SFRH/BD/108224/2015). P. Acevedo is supported by the 'Spanish Ministerio de Economía y Competitividad' (MINECO) and 'Universidad de Castilla-La Mancha' (UCLM) through a ‘Ramón y Cajal’ contract (RYC-2012-11970). Finally, this work was developed in the scope of the MARE strategic programme funded by FCT (PEst – UID/MAR/04292/2013).Peer Reviewe