Effect of the allelochemicals from the macrophyte Egeria densa on the competitive interactions of pelagic and littoral cladocerans

ABSTRACT

Macrophytes release allelochemicals, which affect pelagic cladocerans such as Daphnia. Using population growth experiments, we analysed the effects of allelochemicals from the macrophyte Egeria densa on the interaction between Daphnia mendotae and three littoral cladocerans (Diaphanosoma birgei, Macrothrix triserialis and Simocephalus mixtus). We found that allelochemicals from E. densa increased the abundance of all the tested cladocerans in spite of the presence of a competitor. This effect was stronger (nearly three to four times higher than in controls) for D. birgei and M. triserialis in the absence of D. mendotae. Independent of the presence of allelochemicals, S. mixtus, but not D. birgei and M. triserialis, reduced the abundance of D. mendotae as compared to controls. The rate of population increase (r) per day was significantly elevated due to the presence of Egeria’s allelochemicals (from 0.07–0.16 d⁻¹ without allelochemicals against 0.12–0.24 d⁻¹ with allelochemicals). In our competition experiments, the rates of population increase of the cladocerans were lower than those in single-species cultures when cultured in the absence of allelochemicals. However, in the presence of allelochemicals this trend was not consistent. Thus, the positive effects of Egeria’s allelochemicals over the cladoceran populations may enhance the grazing pressure on phytoplankton.

KEYWORDS:

• Submerged macrophyte
• zooplankton
• allelopathy
• rate of population increase

Acknowledgements

Thanks are due to Carolyn Brown (Canada) Katya Frank (Mexico) and Sylvia Welke (Canada) for language corrections.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Cristian Alberto Espinosa-Rodríguez, obtained his Doctoral Degree in 2016, is an aquatic ecologist. His main interests are centred around the effects of allelochemicals from the invasive macrophytes on the plankton. He also studies the competitive interactions among rotifers and cladocerans and the role of the food quality on the zooplankton dynamics.

S.S.S. Sarma, Professor of Limnology, National Autonomous University of Mexico at the Campus Iztacala. His areas of research interests are mainly Taxonomy, Ecology and Ecotoxicology of Rotifera, Cladocera, Copepoda, Ostracoda and Anostraca. He has authored more than 200 research publications indexed in Web of Science.

S. Nandini, Professor of Limnology, National Autonomous University of Mexico at the Campus Iztacala. She studies the toxicity of cyanobacteria blooms and their control, feeding ecology of larval fish and axolotls using as zooplankton as prey and the ecology of cladocerans, copepods, ostracods and amphipods. She has authored about 175 scientific articles indexed in Web of Science.

Additional information

Funding

CAER thanks CONACyT (grant number CVU 257869) and the Postgraduate Programme in Marine Sciences and Limnology (PCML) for a doctoral scholarship.