Abstract
Small pelagics are small fish species often schooling that mainly feed on planktonic organisms and are foragingspecies of larger animals. These species have experienced important declines in their wild populations during thelast decades. For instance, the decrease of the European sardine (Sardina pilchardus) body condition has had adetrimental impact on its landings, leaving their commercial fishing unprofitable in some Mediterranean areas.The causes for this decline are not clearly established but seems to be mainly related to changes with planktoniccommunities inducing a switch in their foraging behaviour from particulate-feeding to filter-feeding. Moreover,it has been highlighted that sardines ingest plastic fibres throughout their natural spatial distribution, suggestingthis additional pollution as a possible new threat affecting their populations’ health. In this study we developpedan experimental setup allowing us to maintain wild fish in captive controlled conditions in order to test thepossible factors affecting plastic fibres ingestion in sardines. We demonstrate that sardines ingest fibres fromwater, and the amount of fibres ingested is highly impacted by their feeding behaviour. Sardines feeding byfiltration ingest less food but more plastic fibres (mean = 4.95 fibres/ind; SD = 3.43), compared to sardines thatfeed by particulate-feeding (mean = 0.6 fibres/ind; SD = 1.04). Moreover, a decrease in sardine body conditionfactor was detected for filter-feeding individuals, mostly linked to the lower amount of food they ingested ratherthan to the fibre ingestion itself. Nonetheless, higher water temperature seems to accelerate the pattern of fibreexpulsion in filter-feeding sardines. Alltogether, it is suggested that plastic fibres pollution and phytoplanctonicchanges under global change, might synergistically act at disturbing the health of this species in wildpopulations.