Do interactions between eutrophication and CO2 enrichment increase the potential of elodeid invasion in tropical lakes?

• Published in: Biological invasions Vol. 22; no. 9; pp. 2787 - 2795
• Main Authors: Mormul, Roger Paulo, Thomaz, Sidinei Magela, Jeppesen, Erik
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-09-2020; Springer Nature B.V
• Subjects: Aquatic plants; Biomedical and Life Sciences; Carbon dioxide; Climate change; Developmental Biology; Ecology; Enrichment; Eutrophic environments; Eutrophic waters; Eutrophication; Factorial experiments; Fresh water; Freshwater & Marine Ecology; Growth rate; Hydrocharitaceae; Introduced species; Invasive plants; Invasive species; Life Sciences; Macrophytes; Nonnative species; Original Paper; Phytoplankton; Plant growth; Plant Sciences; Success; Tropical lakes; Climate change; Nutrient availability; Macrophytes; Regime shifts
• ISSN: 1387-3547; 1573-1464
• DOI: 10.1007/s10530-020-02284-8

Understanding the roles of eutrophication and CO
2
enrichment in the invasive success of aquatic plants is an ecological challenge with relevance to climate change. We tested the hypotheses that (1) eutrophication of freshwaters increases the invasive success of the submersed aquatic plant
Hydrilla verticillata
; (2) CO
2
-enrichment makes freshwater systems more prone to
H. verticillata
invasion; and (3) interactions between eutrophication and CO
2
enrichment increase the potential of
H. verticillata
invasion. We carried out a factorial experiment crossing eutrophication (nutrient and phytoplankton addition) and CO
2
enrichment to compare the growth attributes of the invasive
H. verticillata
with those of the native
Egeria najas
(both Hydrocharitaceae). We found that eutrophication and CO
2
enrichment had different effects on growth attributes. Eutrophication decreased the growth rate and lateral branch formation of both species, but the invasive species continued producing more branches than the native one. These results suggest that the invasive species has an increased advantage for spreading under eutrophic conditions. In contrast, CO
2
enrichment increased the growth rate and lateral branch formation of both species, but only under eutrophic conditions. Consequently, CO
2
enrichment largely counteracted the negative effects of eutrophication on these two macrophytes. Our results indicate that the interaction between freshwater CO
2
enrichment and eutrophication may enhance the invasion success of
H. verticillata
, and potentially other Hydrocharitaceae, due to an increase plant growth and in propagule pressure.