Warming and Eutrophication Effects on Phytoplankton Community of Two Tropical Systems with Different Trophic States—An Experimental Approach

Abstract

Global warming, as well as europhication are predicted to promote cyanobacterial blooms, but how tropical phytoplankton communities from different trophic state systems respond to temperature variation is less known. To further explore the effect of temperature changes and nutrient addition on phytoplankton communities and to get insight in possible resistance to these effects, we tested the hypothesis that temperature variation will have a stronger effect on cyanobacteria dominance in eutrophic water than in oligo-mesotrophic. Hereto, we conducted an experiment with phytoplankton communities from two aquatic ecosystems differing in trophic state. Water samples from a eutrophic and an oligo-mesotrophic system were collected and incubated in 25 and 30ºC. Also, treatments that received additional surplus N and P were included that served as eutrophication treatments. Temperature variation itself did not promote cyanobacteria in either water from the oligo-mesotrophic or the eutrophic system. However, nutrient enrichment of water from the eutrophic system significantly boosted cyanobacteria, and biomass increased 10 times in both 25ºC and 30ºC treatments. In contrast, eutrophication of water from the oligo-mesotrophic system did not change the relative contribution of phytoplankton groups and response ratios were much lower than those for water from the eutrophic system. Although using a very simple experimental design, the results suggest that in eutrophic systems cyanobacteria dominance can be favoured by further addition of nutrients, independently of a direct temperature effect and that more pristine environments possess some resistance against eutrophication. Since global warming is assumed to intensify eutrophication symptoms indirectly, our study underscores the importance of nutrient control.

Phytoplankton Communities of Temporary Ponds Under Different Climate Scenarios: Experiments on Vernal Pool Microcosms

“…This is surprising and inconsistent with many other studies (conducted on permanent water bodies), which showed that cyanobacteria have a high growth potential at elevated temperatures [59][60][61][62][63] ranging from 20 to 35ºC 22 , and they usually increase their abundance and biomass with global warming 27,33,64 . According to 65 and 66 climate warming may also favour cyanobacteria indirectly, by enhancing the eutrophication of freshwater environments 28,67 . An experimental studies upon the climate changes in a shallow subtropical lake 68 showed, that phytoplankton community structure was more affected by nutrient enrichment than by temperature increase.…”

Phytoplankton structure is more influenced by nutrient enrichment than by temperature increase: an experimental approach upon the global changes in a shallow subtropical lake

“…Freshwater ecosystems are particularly vulnerable to climate changes because they are relatively isolated and fragmented physically within large terrestrial landscapes (Woodward et al, 2010). Eutrophication processes and increased temperature might affect the structure and function of lakes and ponds (Carvalho & Kirika, 2003;Gomes et al, 2017). Some studies have examined the different aspects of intensifying global eutrophication (Pasternak et al, 2009), but little is known about the actual effects that this interaction (temperature and eutrophication) may cause in aquatic ecosystems (Carvalho & Kirika, 2003).…”

“…Attempts to predict the possible effects of global climate change in temperate aquatic environments have involved experimentation (Davis et al, 2009;Feuchtmayr et al, 2010) and the use of modeling (Domis et al, 2007;Elliott & Defew, 2011). However, the drivers of climate change will have varied effects on lakes, depending on the geographical location, altitude, morphometry, climate, vegetation and land use (Adrian et al, 2009;Deng et al, 2016;Gomes et al, 2017). In agricultural catchments, for example, changes in precipitation and organic-matter decomposition may alter mainly the import of nutrients into water bodies (Adrian et al, 2009).…”