Ecological singularity of temperate mesopredatory myliobatoid rays (Chondrichthyes: Myliobatiformes)

LUIS O. LUCIFORA; NATALIA L. RUOCCO

MARINE AND FRESHWATER RESEARCH

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2017 vol. 68 p. 1098 - 1111

1323-1650

p { margin-bottom: 0.25cm; direction: ltr; color: rgb(0, 0, 0); line-height: 120%; }p.western { font-family: "Liberation Serif","Times New Roman",serif; font-size: 12pt; }p.cjk { font-family: "Droid Sans Fallback"; font-size: 12pt; }p.ctl { font-family: "FreeSans"; font-size: 12pt; }Many myliobatoid rays are important mesopredatorshaving significant effects on coastal benthic communities. Intropical and subtropical, high-diversity, oligotrophic ecosystemsthey partition their trophic resources, which results in highecological singularity. However, it is unknown if this is true fortemperate, low-diversity, eutrophic ecosystems. In this paper, wetest, for the first time, the hypothesis that myliobatoidmesopredators are ecologically redundant in a temperate,low-diversity, eutrophic ecosystem. We quantified diet, measuredintra and inter-specific trophic overlap in the three species thatregularly occur off Uruguay and northern Argentina: Myliobatisgoodei, M.ridens and Dasyatishypostigma. Myliobatisridens had a typical durophagic dietcomposed of bivalves and gastropods. Myliobatisgoodei fed mainly on polychaetes anddecapods, diverging from the durophagic diet typical of its genus.Dasyatis hypostigmapreyed mainly on amphipods and decapods. There were ontogenetic andseasonal dietary differences in all three species. It is concludedthat ecological singularity is present in this temperate myliobatoidassemblage, with each species having a different trophic niche. Thepractice of pooling together myliobatoid mesopredators in trophicmodels must be abandoned unless there is evidence of ecologicalredundancy.p { margin-bottom: 0.25cm; direction: ltr; color: rgb(0, 0, 0); line-height: 120%; }p.western { font-family: "Liberation Serif","Times New Roman",serif; font-size: 12pt; }p.cjk { font-family: "Droid Sans Fallback"; font-size: 12pt; }p.ctl { font-family: "FreeSans"; font-size: 12pt; }Many myliobatoid rays are important mesopredatorshaving significant effects on coastal benthic communities. Intropical and subtropical, high-diversity, oligotrophic ecosystemsthey partition their trophic resources, which results in highecological singularity. However, it is unknown if this is true fortemperate, low-diversity, eutrophic ecosystems. In this paper, wetest, for the first time, the hypothesis that myliobatoidmesopredators are ecologically redundant in a temperate,low-diversity, eutrophic ecosystem. We quantified diet, measuredintra and inter-specific trophic overlap in the three species thatregularly occur off Uruguay and northern Argentina: Myliobatisgoodei, M.ridens and Dasyatishypostigma. Myliobatisridens had a typical durophagic dietcomposed of bivalves and gastropods. Myliobatisgoodei fed mainly on polychaetes anddecapods, diverging from the durophagic diet typical of its genus.Dasyatis hypostigmapreyed mainly on amphipods and decapods. There were ontogenetic andseasonal dietary differences in all three species. It is concludedthat ecological singularity is present in this temperate myliobatoidassemblage, with each species having a different trophic niche. Thepractice of pooling together myliobatoid mesopredators in trophicmodels must be abandoned unless there is evidence of ecologicalredundancy.