Mussel, Seagrass and Calcareous Algal Interactions: Influence of CO2 and pH on Photosynthesis and Calcification in a Tropical Bay
(English)Manuscript (Other academic)
Changes in seawater pH and thus, the inorganic carbon (Ci) composition brought about by photosynthetic carbon uptake have been shown to influence the productivity of marine plants. In this work, we enclosed different combinations of seagrasses Thalassia hemprichii, the mussel Pinna muricata and the calcareous coralline algae Amphiroa fragilissima in open plastic cylinders in a tropical seagrasses meadow at Fumba Bay, Zanzibar, Tanzania, while measuring pH and rates of photosynthesis and calcification. The results showed that the photosynthetic production of seagrasses increased in the presence of mussels (probably due to their supply of respiratory CO2) while the presence of seagrasses supported an increase in calcification of the coralline algae (probably by the higher pH generated by the former). Photosynthetic rates of the seagrasses and the coralline algae were ~20% and ~13% higher, respectively, in the presence of mussels than in their absence. Also, the rate of calcification of the coralline algae was significantly higher (by 11%) in the presence of seagrasses than when alone. Calcification by the mussels, on the other hand, was not affected by the presence of algae or seagrasses. These results illustrate how pH changes induced by fluxes in Ci can act as a factor controlling both productivity and calcification in densely populated shallow marine ecosystems.
Coralline algae, Calcification, Mussels, pH, Photosynthesis, Seagrasses
Research subject Plant Physiology
IdentifiersURN: urn:nbn:se:su:diva-27478OAI: oai:DiVA.org:su-27478DiVA: diva2:214426