Abstract
ABSTRACT The purpose of this research was to investigate differences in diet composition between Achirus mazatlanus and Syacium ovale, two flatfishes inhabiting in a tropical coastal lagoon and to investigate the relationship of their feeding habits to size, body morphometry and mouths characteristics. Fish were collected during sampling trips conducted regularly from 2011 to 2016 using several types of fishing gear. Total number of analyzed stomachs with some food content was 328 for Achirus mazatlanus from 1.4 to 21.3 cm total length (TL) and 203 for Syacium ovale with 1.3 to 24.0 cm TL. Results indicate that both species share a general diet based on benthic invertebrates and fishes but S. ovale has a more piscivorous habit, which can be explained by a more slender body shape and larger teeth, characteristics which increase prey fish catching performance. Important changes in composition of food categories related to size were not found for any species, but larger fish of both species eat larger ranges of prey sizes, and this ontogenetic change is consistent with recent developments on optimal foraging theory.
Highlights
Flatfishes are common species in most tropical marine fish assemblages, especially those found on soft-bottom habitats in estuaries and on a variety of substrata on the inner continental shelf (Munroe, 2015)
The mean value of calculated gape area in S. ovale was almost 1.5 times larger than the same variable in A. mazatlanus. The diet of both studied species is formed in a high percentage by invertebrates and fishes, some dissimilarities should be emphasized as supporting the significant differences found in diet composition
Achirus mazatlanus included polychaetes as an important food item and fishes eaten by this species were dominated by one family of benthic fishes (Gobiidae)
Summary
Flatfishes are common species in most tropical marine fish assemblages, especially those found on soft-bottom habitats in estuaries and on a variety of substrata on the inner continental shelf (Munroe, 2015). Species of this group serve as major energy pathways for conversion of benthic production into a form suitable for consumption by higher predators and humans. Flatfishes are critical components of benthic communities and any understanding of marine benthic ecosystems needs to incorporate trophic dynamics of flatfishes (Link et al, 2015) With their similarity in body shape and distinct preference for the benthic layer, flatfish may be more similar in their habits and environmental demands than are other fish (Piet et al, 1998). No published information could be found on feeding habits of S. ovale in estuarine habitats, but Flores-Ortega et al (2013) reported that main food items of this species in Bay of Navidad, Mexico, were scielo.br/ni | sbi.bio.br/ni
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