Spatial and size feeding niche partitioning of the rhomboid mojarra Diapterus rhombeus (Cuvier, 1829) in a tropical Brazilian Bay

Abstract

We examined the stomach contents of 287 individuals of rhomboid mojarra Diapterus rhombeus collected between June 1999 and May 2000 in three zones (inner, middle and outer) of a Brazilian tropical bay. Fish were grouped in five size-class (Total Length₁ ≤ 80 mm; TL₂=81–110; TL₃=111–140; TL₄=141–170; and TL₅ ≥ 171). The aim was to assess whether intraspecific spatial and size-feeding niche partitioning occurs and to describe the strategy used to explore the available resources. Crustacea and Polychaeta were the most important trophic categories and Harpacticoida (Index of Relative Importance, IRI = 66.9%) was the most preferred prey throughout all zones and size classes. The smallest individuals (TL≤140 mm) occurred exclusively in the inner zone and fed mainly on Harpacticoida, Calanoida, sedentary Polychaeta and Nematoda, while the largest individuals (TL>140 mm) fed mainly on Harpaticoida and Ostracoda. In the outer zone, the largest individuals feed mainly on Harpacticoida and Caprella. A high within-phenotype contribution to the niche width and a generalist zoobenthivore feeding strategy were detected. Partitioning the food items along space and growth seems to be the mechanism used by this species to decrease intraspecific competition.

Keywords:

• Tropical bays
• demersal fishes
• feeding habits
• mojarras
• partitioning resources

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We thank Iracema David Gomes and Márcia Cristina Costa Azevedo for helping in fieldwork. This work was financially supported by CNPq – Brazilian National Agency for Scientific and Technological Development (Proc. 302878/2005-0 and 302555/2008-0) and FAPERJ (Rio de Janeiro State Agency for Research Development (Proc. E-26/170.258/2001).

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark