Risk-sensitive foraging does not explain condition-dependent choices in settling reef fish larvae

PeerJ

article

Emma E. Bogdan¹  Andrea L. Dingeldein¹  Deirdre Bertrand¹  Will White² 

[1]Department of Biology and Marine Biology, University of North Carolina at Wilmington

[2]Department of Fisheries and Wildlife, Coastal Oregon Marine Experiment Station, Oregon State University

关键词: Larval fish;    Coral reef fish;    Risk-sensitive foraging;    Group joining;    Otolith;    Thalassoma bifasciatum;   

DOI  :  10.7717/peerj.8333

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

The transition from the planktonic larval to the benthic adult stage in reef fishes is perilous, and involves decisions about habitat selection and group membership. These decisions are consequential because they are essentially permanent (many fish rarely leave their initial settlement habitat, at least for the first several days or weeks). In one common Caribbean reef fish, the bluehead wrasse (Thalassoma bifasciatum), settling larvae either join groups or remain solitary. Grouped fish have lower mortality rates but slightly slower growth rates, and fish that are smaller at the time of settlement are less likely to join groups. We hypothesized that the decision of smaller (i.e., lower condition) fish to remain solitary could be explained by risk-sensitive foraging: with less competition, solitary fish may have higher variance in foraging success, so that there is a chance of a high payoff (outweighing the increased mortality risk) despite the lack of a large difference in the average outcome. We tested this by comparing the mean, standard deviation, and maximum number of (a) prey items in stomach contents and (b) post-settlement growth rates (from otolith measurements) of solitary and grouped fish during two settlement pulses on St. Croix, US Virgin Islands. However, we did not find evidence to support our hypothesis, nor any evidence to support the earlier finding that fish in groups have lower average growth rates. Thus we must consider alternative explanations for the tendency of smaller fish to remain solitary, such as the likely costs of searching for and joining groups at the time of settlement. This study reinforces the value of larval and juvenile fish as a testbed for behavioral decisionmaking, because their recent growth history is recorded in their otoliths.

【 授权许可】

CC BY