Variability of trophic ecology in two teleost species associated with lagoonal habitats (Great Reef of Toliara, SW Madagascar)
- Authors
- Publication Date
- Oct 01, 2024
- Source
- ORBi
- Keywords
- Language
- English
- License
- Unknown
- External links
Abstract
peer reviewed / Since the pioneering work in 70’, relatively few studies looked at the trophic niches of teleost reef fishes in Madagascar. The lagoon of Toliara (SW Madagascar) is facing threat from the use of mosquito net trawls, often practiced in seagrass and fringing reef habitats. These practices have the potential to induce alterations in the ecological dynamics of the species and in their feeding behaviors. The primary objective of this study is to investigate the dietary preferences and their potential interannual and spatial variation in two teleost fish species frequently found in mosquito net trawl: the rabbitfish Siganus sutor as juveniles and the goby Oplopomus oplopomus as adults. Sampling was conducted at two distinct sites, Ankilibe and Sarodrano, over a two-year period, in December of both 2017 and 2018. The diet composition of these two species was assessed through the examination of their stomach contents and the analysis of stable isotopes (δ13C and δ15N) from a sample of 40 individuals during each field campaign. A total of 22 different food items were identified in the stomach of young S. sutor, with seagrass and benthic mobile prey items being predominant. In adult O. oplopomus, 21 food items were identified, with a high representation of mobile benthic prey and zooplankton. Analyses of stomach contents and stable isotopes revealed significant variations in diet composition across different years and spatial locations. In addition, the results indicated a significant variation in diet according to the size of the individuals studied. The present study is one of the few documenting trophic variations in reef fishes, highlighting some feeding plasticity which could be highly valuable for a rapid adaptation in changing environments.
