Benthic macroinvertebrate communities of three tropical, warm monomictic Mexican lakes

Abstract

Abstract Most studies of benthic macroinvertebrate communities are from shallow lakes or restricted to the littoral zone of deep, temperate lakes, with just a few dealing with the deep benthos. Furthermore, the deep benthic macroinvertebrate communities of tropical lakes are almost unknown. The present work describes the benthic macroinvertebrate communities of three tropical, warm monomictic lakes in “Lagunas de Montebello” National Park, Mexico, by describing the differences along the bathymetric profile, from the littoral down to the profound benthos. We studied the benthic macroinvertebrate communities in the two contrasting hydrodynamic periods of the warm monomictic lakes: a) stratification, when the hypolimnion becomes anoxic, and b) mixing, when the water column becomes oxygenated. We expected: 1) a reduction in the benthic macroinvertebrate taxonomic richness, density, and biomass from the littoral to the deep zone, 2) an impoverished benthic macroinvertebrate community while stratified (anoxia) compared to mixing (oxygenated), and 3) depletion in the taxonomic richness, density, and biomass of the profundal benthic macroinvertebrates in the tropical compared to temperate lakes. We found: 1) a decreasing trend in taxonomic richness (6\u202f±\u202f2–3\u202f±\u202f1 taxa), density (1868.7\u202f±\u202f1069.7–349.1\u202f±\u202f601.8\u202fin. m−2) and biomass (277.8\u202f±\u202f188.9–85.1\u202f±\u202f95.6\u202fmg C m−2) from the littoral to the deep zone; chironomids dominated the littoral zone, while oligochaetes dominated the deep zone. 2) Lower density and biomass but not taxonomic richness while stratified (4\u202f±\u202f3 taxa; 586.2\u202f±\u202f527.6\u202fin. m−2; 81.6\u202f±\u202f164.3\u202fmg C m−2) compared to mixing (4\u202f±\u202f3 taxa; 877.5\u202f±\u202f1051.4\u202fin. m−2; 190.1\u202f±\u202f131.1\u202fmg C m−2). 3) lower taxonomic richness and density but not biomass in tropical Montebello oligotrophic lakes (3\u202f±\u202f3 taxa; 349.1\u202f±\u202f601.8\u202fin. m−2; 85.1\u202f±\u202f195.6\u202fmg C m−2) compared to temperate analogous (2–48 taxa; 492−83,189 8\u202fin. m−2; 0.13−201.5\u202fmg\u202fm−2). We conclude the early onset and long-lasting hypolimnetic anoxia restrict the benthic macroinvertebrate community radiation and diversification in tropical, oligotrophic, warm monomictic lakes.