Phytoplankton Diversity Relates Negatively with Productivity in Tropical High-Altitude Lakes from Southern Ecuador

Abstract

Tropical high-altitude lakes are vital freshwater reservoirs in the Andean regions. They are heavily threatened by human activities that may alter their functioning and hamper the provisioning of key ecosystem services such as water supply. Despite their ecological and social relevance, we know little about these waterbodies, especially regarding the factors influencing their functioning. Here, we explored the links between several environmental variables and phytoplankton productivity, measured as chlorophyll-a concentration and total phytoplankton biovolume. For this, we sampled twenty-four tropical high-altitude lakes located over three-thousand meters above sea level in Southern Ecuador. We found that four abiotic factors combined explained 76% of the variation in chlorophyll-a concentration amongst lakes. Contrary to what studies from temperate regions suggest, taxa richness was not related to either chlorophyll-a concentrations or total phytoplankton biovolume. Moreover, phytoplankton biovolume diversity was negatively correlated to both chlorophyll-a concentrations and total phytoplankton biovolume. This was due to a very uneven distribution of productivity amongst taxa in the more productive lakes. To the best of our knowledge, this is the first attempt to explore the determinants of phytoplankton functioning in tropical high-altitude lakes. We hope that this study will help to establish a baseline for evaluating the consequences of human activities in the ecology and functioning of this vital but fragile ecosystem. Our results suggest that by modifying the abiotic and biotic parameters of tropical high-altitude lakes, human activities can indirectly impact their functioning and their capacity to provide vital ecosystem services.

Limnochemistry and Plankton Diversity in Some High Altitude Lakes of Kashmir Himalaya

“…As only few diatomic species are able to survive in these extreme habitats, may explain to some extent the low diversity reported in this study (Lotter and Bigler, 2000). The low diversity is normally attributed to low productivity of the lakes and harsh environmental conditions Cartuche et al (2019) but equally the number of samplings conducted may also have role to play in underestimation of the diversity. The overall phytoplankton composition and abundance suggest oligotrophic status of these lakes (Kumar et al, 2012).…”

Highest Composition Dissimilarity among Phytoplankton Communities at Intermediate Environmental Distances across High-Altitude Tropical Lakes

“…The Tres Lagunas system is a group of shallow, tropical high-altitude lakes located in Southern Ecuador at an average altitude of 3323 m above sea level (Figure 1). For this study, we included 24 lakes with wide ranges of physicochemical and biotic characteristics (Table 1, Table S1 in supplementary material) separated by around one hundred meters to up to six kilometers from each other [27].…”

“…A large cluster of seven lakes (8,19,18,16,21,23,14) dominated by Pyrrophyta was revealed. Finally, a group of six lakes (1,6,27,28,17,30) with no clear-cut dominance of one phylum was also depicted.…”