The role of ecophysiological and behavioral traits in structuring the zooplankton assemblage in a deep, oligotrophic, tropical lake

Abstract

Zooplankton inhabiting deep, oligotrophic, tropical lakes must cope with scenarios where the combination of resource limitation, high visual‐predation risk, UV‐induced damage and seasonal development of anoxic waters, entail particular challenges for organisms, uncommon in temperate environments. We assessed the diel vertical migration—DVM—(UV/predation‐avoidance strategy), numerical response, and starvation resistance (physiological strategies to cope with food scarcity) of the copepod Leptodiaptomus garciai and the rotifers Hexarthra jenkinae and Brachionus sp. “Mexico,” which constitute the zooplankton assemblage of Alchichica, a high‐altitude, deep, oligotrophic, hyposaline, warm‐monomictic lake located in Mexico. L. garciai followed the normal pattern of DVM in all seasons; with organisms concentrated ≈ 20 m deeper than the depth of 1% photosynthetically active radiation at mid‐day, with evasion from the planktivore Poblana alchichica as the most probable driver. However, copepods could not evade the euphotic zone owing to the anoxic conditions of the hypolimnion during the well‐established stratification period. Rotifers did not migrate vertically. The dominance of copepods throughout the year can be explained by their low food threshold, high proportion of usable reserves and the lowest rate of mass loss at food deprivation. Contrastingly, rotifers are scarce and intermittent due to frequent resource limitation and because they lose mass at higher rates. However, they are able to suddenly increase due to their high growth rates. We demonstrated that the interaction between environmental constraints and the specific combinations of traits can explain zooplankton structure in the lake. This study enlightens the necessity to improve current limnological models with data from tropical lakes.

Phenotypic plasticity of life-history traits of a calanoid copepod in a tropical lake: Is the magnitude of thermal plasticity related to thermal variability?

“…The copepod L . garciai is the main component of the zooplankton assemblage; in a previous paper we concluded that it is present throughout the year despite the often-limiting availability of phytoplankton, owing to its low food threshold (C 0 ) and high resistance to starvation; in addition, it performs diel vertical migrations to avoid light-related mortality factors (UV damage and/or predation risk) [ 27 ]. There are also two rotifer species ( Brachionus sp.…”

“…As we intend to describe the environmental conditions experienced by copepods at a given day, we took into account that adult individuals of L . garciai perform diel vertical migrations–moving across a vertical gradient of biotic and abiotic conditions- and avoid the anoxic hypolimnion during the summer stratification of the lake [ 27 ]. In addition, we assumed they also evade the surface of the water column as has been observed in crustacean zooplankton inhabiting other highly transparent lakes [ 29 ].…”

“…Phytoplankton is evenly distributed in the water column during the mixing period and forms a deep chlorophyll maximum at the metalimnion (DCM) during the stratification [ 26 , 27 ]. We obtained phytoplankton samples with a Niskin-type bottle (6 L) at 10 and 25 m when the water column was mixing and at the epilimnion (8.5 m) and the DCM when the lake was stratified.…”

Plankton Community Stability and Its Relationship with Phytoplankton Species Richness in Lake Nansihu, China

“…However, until recently, the influence of phytoplankton diversity on the stability of zooplankton and the underlying mechanisms remained unclear. In addition, both phytoplankton and zooplankton are complex in taxonomic composition, and these groups have their own ecophysiological traits [18,37]. It remains unknown whether the temporal stability of these plankton taxa responds similarly to variations in diversity.…”

Inter-annual ciliate distribution variation within the late stratification oxycline in a monomictic lake, Lake Alchichica (Mexico)

“…Among them, Lake Alchichica investigations have included both general limnology and all trophic levels (cf., Macek et al, 2009;Oliva et al, 2001;Ciros-Pérez et al, 2015, for bacteria, phytoplankton and zooplankton / fish interactions, respectively). Subtropical lakes Biwa (Japan) and Kinneret (Israel) have also been well studied (Madoni, 1990;Hu and Kusuoka, 2015).…”