Ocean acidification affects parameters of immune response and extracellular pH in tropical sea urchins Lytechinus variegatus and Echinometra luccunter.
The rising concentration of atmospheric CO2by anthropogenic activities is changing the chemistry of the oceans, resulting in a decreased pH. Several studies have shown that the decrease in pH can affect calcification rates and reproduction of marine invertebrates, but little attention has been drawn to their immune response. Thus this study evaluated in two adult tropical sea urchin species, Lytechinus variegatus and Echinometra lucunter, the effects of ocean acidification over a period of 24h and 5days, on parameters of the immune response, the extracellular acid base balance, and the ability to recover these parameters. For this reason, the phagocytic capacity (PC), the phagocytic index (PI), the capacity of cell adhesion, cell spreading, cell spreading area of phagocytic amebocytes in vitro, and the coelomic fluid pH were analyzed in animals exposed to a pH of 8.0 (control group), 7.6 and 7.3. Experimental pH's were predicted by IPCC for the future of the two species. Furthermore, a recovery test was conducted to verify whether animals have the ability to restore these physiological parameters after being re-exposed to control conditions. Both species presented a significant decrease in PC, in the pH of coelomic fluid and in the cell spreading area. Besides that, Echinometra lucunter showed a significant decrease in cell spreading and significant differences in coelomocyte proportions. The recovery test showed that the PC of both species increased, also being below the control values. Even so, they were still significantly higher than those exposed to acidified seawater, indicating that with the re-establishment of the pH value the phagocytic capacity of cells tends to restore control conditions. These results demonstrate that the immune system and the coelomic fluid pH of these animals can be affected by ocean acidification. However, the effects of a short-term exposure can be reversible if the natural values ​​are re-established. Thus, the effects of ocean acidification could lead to consequences for pathogen resistance and survival of these sea urchin species.
Department of Cell and Developmental Biology, Institute of Biomedical Science, University of São Paulo, Av Prof. Lineu Prestes, 1524, CEP 05509-900, São Paulo, SP, Brazil. Electronic address: debora.figueal@gmail.com.
Débora Alvares
DA
Leite Figueiredo
Department of Cell and Developmental Biology, Institute of Biomedical Science, University of São Paulo, Av Prof. Lineu Prestes, 1524, CEP 05509-900, São Paulo, SP, Brazil.
Paola Cristina
PC
Branco
Department of Cell and Developmental Biology, Institute of Biomedical Science, University of São Paulo, Av Prof. Lineu Prestes, 1524, CEP 05509-900, São Paulo, SP, Brazil.
Douglas Amaral
DA
Dos Santos
Department of Cell and Developmental Biology, Institute of Biomedical Science, University of São Paulo, Av Prof. Lineu Prestes, 1524, CEP 05509-900, São Paulo, SP, Brazil.
Andrews Krupinski
AK
Emerenciano
Department of Cell and Developmental Biology, Institute of Biomedical Science, University of São Paulo, Av Prof. Lineu Prestes, 1524, CEP 05509-900, São Paulo, SP, Brazil.
Renata Stecca
RS
Iunes
Metropolitan United Faculties, Scholl of Veterinary Medicine, Rua Ministro Nelson Hungria, 541, São Paulo, SP, Brazil; Universidade Paulista, Av. Marquês de São Vicente, 3001 - Água Branca - São Paulo - Brazil.
João Carlos
JC
Shimada Borges
Department of Cell and Developmental Biology, Institute of Biomedical Science, University of São Paulo, Av Prof. Lineu Prestes, 1524, CEP 05509-900, São Paulo, SP, Brazil.
José Roberto
JR
Machado Cunha da Silva
D000136:Acid-Base Equilibrium / Q000502:physiology; D000818:Animals; D057231:Climate Change; D005260:Female; D006863:Hydrogen-Ion Concentration; D007113:Immunity, Innate / Q000502:physiology; D047331:Lytechinus / Q000276:immunology / Q000502:physiology; D008297:Male; D010586:Phagocytes / Q000502:physiology; D012617:Sea Urchins / Q000276:immunology / Q000502:physiology*; D012623:Seawater / Q000737:chemistry*
Climate change; Echinometra lucunter; Innate immunity; Lytechinus variegatus; Ocean acidification; Sea urchin