Size assortment in mixed-species groups of juvenile-phase striped parrotfish (Scarus iserti) in The Bahamas

Abstract

Striped parrotfish (Scarus iserti) often form heterospecific groups with other reef fishes. In this study, we examined the species and body size composition of these groups on reefs in The Bahamas. Groups averaged approximately 4 S. iserti and 2 associated species, with surgeonfish (Acanthurus chirurgus and A. bahianus), slippery dick (Halichoeres bivittatus), and bluehead wrasse (Thalassoma bifasciatum) as the most common associates. Fewer groups than expected had only 1 associate; groups with 3 or more associates were more common than expected. Both the S. iserti and associated species tended to be closely sizematched within a group, perhaps due to benefits of size assortment in lowering predation risk. Likewise, the high frequency of groups with greater than a single associate species suggests that associates may benefit from not being the only phenotypically different individual in a group.

Coexisting mangrove‐coral habitat use by reef fishes in the Caribbean

“…These two species are known to coexist; H. bivittatus is a common associate in mixed‐species shoals with Scarus spp. (Quinn et al, 2012). Moreover, Scarus spp.…”

The shoaling behavior of two cyprinid species in conspecific and heterospecific groups

“…However, mixed-species shoals are also frequently found among a wide range of animal taxa and provide advantages in terms of enhanced foraging efficiency and predator avoidance ( Goodale et al, 2010 ; Rodgers, Downing & Morrell, 2015 ; Kleinhappel et al, 2016 ). Although it has long been suggested that the presence of multiple species might change individuals’ behavior and position within the shoal ( Allan, 1986 ), the shoaling behaviors of mixed-species groups have received little attention ( Morse, 1977 ; Ward, Axford & Krause, 2002 ; Quinn et al, 2012 ). Thus, little is known about individual-level interactions within heterospecific groups and the mechanisms mediating their structure ( Kleinhappel et al, 2016 ).…”