Marine bioinvasions are of increasing attention due to their potential of causing ecological and economic loss. The seaweed Gracilaria vermiculophylla has recently invaded the Baltic Sea, where, under certain conditions, it was found to outcompete the native alga Fucus vesiculosus. Parasites of grazers and temperature are among the potential factors which might indirectly modulate the interactions between these co-occurring algae through their single and combined effects on grazing rates. We tested the temperature and parasitism effects on the feeding of the gastropod Littorina littorea on F. vesiculosus vs. G. vermiculophylla. Uninfected and trematode-infected gastropods were exposed to 10, 16, 22, and 28 °C for 4 days while fed with either algae. Faeces production was determined as a proxy for grazing rate, and HSP70 expression, glycogen and lipid concentrations were used to assess the gastropod's biochemical condition. Gracilaria vermiculophylla was grazed more than F. vesiculosus. Trematode infection significantly enhanced faeces production, decreased glycogen concentrations, and increased lipid concentrations in the gastropod. Warming significantly affected glycogen and lipid concentrations, with glycogen peaking at 16 °C and lipids at 22 °C. Although not significant, warming and trematode infection increased HSP70 levels. Increased faeces production in infected snails and higher faeces production by L. littorea fed with G. vermiculophylla compared to those which fed on F. vesiculosus, suggest parasitism as an important indirect modulator of the interaction between these algae. The changes in the gastropod's biochemical condition indicate that thermal stress induced the mobilization of energy reserves, suggesting a possible onset of compensatory metabolism. Finally, glycogen decrease in infected snails compared to uninfected ones might make them more susceptible to thermal stress.
Bibliographical noteFunding Information:
We would like to extend our gratitude to Thomas Knura, Björn Buchholz, Renate Schütt, and Nadja Stärck for their valuable technical and scientific input. To Dr. Florian Weinberger for his valuable advice on the sampling of G. vermiculophylla. This study was funded by BMBF/PTJ (Federal Ministry of Education and Research, Germany, grant 03F0821A , PI Wahl and grant 03F0821B , PI B Sures, and the BMBF/MOST grant 3-15216 , PI G Rilov, co-PI T Guy-Haim). Opinions, findings, conclusions and recommendations expressed in this publication are that of the authors, and the BMBF/PTJ accepts no liability whatsoever in this regard. The graphical abstract was created with BioRender.com under agreement number “SU24OFN7KU”.
- Climate change
- Global warming
- Himasthla elongata
- Invasion biology
- Species interactions
ASJC Scopus subject areas
- Environmental Engineering
- Environmental Chemistry
- Waste Management and Disposal