Extreme heat changes post‐heat wave community reassembly

Abstract

Climate forecasts project further increases in extremely high-temperature events. These present threats to biodiversity, as they promote population declines and local species extinctions. This implies that ecological communities will need to rely more strongly on recovery processes, such as recolonization from a meta-community context. It is poorly understood how differences in extreme event intensity change the outcome of subsequent community reassembly and if such extremes modify the biotic environment in ways that would prevent the successful re-establishment of lost species. We studied replicated aquatic communities consisting of algae and herbivorous rotifers in a design that involved a control and two different heat wave intensity treatments (29°C and 39°C). Animal species that suffered heat-induced extinction were subsequently re-introduced at the same time and density, in each of the two treatments. The 39°C treatment led to community closure in all replicates, meaning that a previously successful herbivore species could not re-establish itself in the postheat wave community. In contrast, such closure never occurred after a 29°C event. Heat wave intensity determined the number of herbivore extinctions and strongly affected algal relative abundances. Re-introduced herbivore species were thus confronted with significantly different food environments. This ecological legacy generated by heat wave intensity led to differences in the failure or success of herbivore species re-introductions. Reassembly was significantly more variable, and hence less predictable, after an extreme heat wave, and was more canalized after a moderate one. Our results pertain to relatively simple communities, but they suggest that ecological legacies introduced by extremely high-temperature events may change subsequent ecological recovery and even prevent the successful re-establishment of lost species. Knowing the processes promoting and preventing ecological recovery is crucial to the success of species re-introduction programs and to our ability to restore ecosystems damaged by environmental extremes.

Rotifer community structure in fish-farming systems associated with a Neotropical semiarid reservoir in north-eastern Brazil

“…Likewise, B . havanaensis indicates water temperatures under 27°C, coinciding with the experiments of Seifert, Weithoff and Vos (), whose results indicate that higher temperatures affect negatively this species.…”

Stability of marine phytoplankton communities facing stress related to global change: Interactive effects of heat waves and turbidity

“…Not only was community biovolume still considerably lower than in the control, the community was also still dominated by the small flagellates although diatom biovolume was increasing. Similar differences in algal community composition have been described for the recovery from short-term heat waves of high (29°C and 39°C) intensity (Seifert et al, 2015). Obviously, resilience depended on how the traits that related to resistance and recovery were distributed within the community, which emphasises the importance of dominance structure (evenness) for community stability (Flöder and Hillebrand, 2012;Sasaki and Lauenroth, 2011).…”

“…Chlamydomonas spp. have been shown to dominate phytoplankton communities at high temperatures (Burgmer and Hillebrand, 2011) and are able to withstand small short term heat waves of up to 39°C (Seifert et al, 2015). The co-dominance of R. salina and Chlamydomonas sp.…”

“…Global environmental change, in particular warming, influences ecosystem composition in aquatic and terrestrial systems (Burgmer et al, 2007;Seifert et al, 2015;Stocker, 2014;Stocker et al, 2014). Elevated sea surface temperature causes rapid changes in aquatic communities including changes in the abundance and spatial or seasonal distribution of marine phytoplankton as well as temporal mismatches between trophic levels (Field et al, 2014;Poloczanska et al, 2013;Thiede et al, 2016).…”

“…Although the response of phytoplankton to temperature and turbidity as single stressors has been well studied (Behrenfeld et al, 2006;Boyce et al, 2010;de Jorge and van Beusekom, 1995;Dzialowski et al, 2008;Lewandowska et al, 2012;Seifert et al, 2015;Sloth et al, 1996), until recently, only few studies have analysed the effect of temperature in combination with turbidity (Zehrer et al, 2015). As temperature has direct metabolic effects on cellular processes and often interacts with other factors such as light and nutrients (Boyd et al, 2010), this study focuses on the effects of an interaction between heat wave and turbidity on biovolume, diversity (number of species and their relative abundance as defined by the diversity index H′ (see Washington, 1984) and taxonomic composition of an assembled phytoplankton community.…”