Hide and seek in the Bay of Biscaya functional investigation of marine megafauna and small pelagic fish interactions
|Author(s)||Lambert Charlotte1, Authier Matthieu2, Doray Mathieu3, Doremus Ghislain2, Spitz Jerome2, Ridoux Vincent1, 2|
|Affiliation(s)||1 : Univ La Rochelle, CNRS, UMR 7372, Ctr Etud Biol Chize, 5 Allees Ocean, F-17000 La Rochelle, France.
2 : Univ La Rochelle, Observ Pelagis, UMS 3462, CNRS, 5 Allees Ocean, F-17000 La Rochelle, France.
3 : IFREMER, EMH, Rue Ile Yeu,BP 21105, F-44311 Nantes 03, France.
|Source||Ices Journal Of Marine Science (1054-3139) (Oxford Univ Press), 2019-01 , Vol. 76 , N. 1 , P. 113-123|
|WOS© Times Cited||5|
|Keyword(s)||Bay of Biscay, cetaceans, functional traits, marine top predators, predator avoidance, predator-prey interactions, prey profitability, seabirds|
Prey and predator distributions influence one another. Understanding the scale and the orientation of predator-prey spatial correlations is crucial in foraging ecology. Growing evidence suggests that predator-prey interactions are more constrained by functional characteristics of both the predator and the prey. Unfortunately, in marine pelagic systems, the scale and orientation of spatial correlations between predators and prey have been only little explored from a functional point of view. We tested the existence of fine-scale association between predators and fish functional groups. Visual predator sightings and acoustic fish records were collected synchronously during oceanographic surveys from 2004 to 2014. Prey biomass was integrated by nautical miles and split into four size classes (<10 cm; 10-20 cm; 20-30 cm; >30 cm) and two depth layers (surface, deep). We computed the relative biomass by prey size and depth category from 0 to 12 nm around predator sightings to determine the predators' proximity to local prey biomass. Two cetaceans (common, bottlenose dolphins) and three seabirds (northern gannets, auks, northern fulmars) were studied. No association was found in fulmars, indicating they probably do not feed on considered fishes in the area. Gannets and auks were positively correlated with local prey biomass for sizes <20 cm at both depth layers. Significant negative relationships were found between common dolphins and prey size classes <20 cm at both depth layers, and between bottlenose dolphins and all size ranges at the deeper layer. Our results suggest that the fine-scale spatial overlap of predator and prey is influenced by their functional traits, and that prey exhibit predator avoidance behaviour in presence of swimming predators but not of flying ones.