Influence of thermal stress and bleaching on heterotrophic feeding of two scleractinian corals on pico-nanoplankton

• Published in: Marine pollution bulletin 2020-09, Vol.158, p.111405-111405, Article 111405
• Main Authors: Sangmanee, Kanwara, Casareto, Beatriz E., Nguyen, The Duc, Sangsawang, Laddawan, Toyoda, Keita, Suzuki, Toshiyuki, Suzuki, Yoshimi
• Format: Article
• Language: English
• Subjects: Bleaching; Carbon/nitrogen ratio; Cells; Coral bleaching; Coral feeding; Coral reefs; Corals; Feeding; Feeding rates; Heat; Heat stress; Heat tolerance; Montipora digitata; Nannoplankton; Organic matter; Pico-nanoplankton; Porites lutea; Thermal stress; Threatened species; Vulnerability; Water heating
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2020.111405

The feeding strategies of Montipora digitata and Porites lutea, two dominant corals in the Okinawan reefs, were investigated. The focus was on pico- and nanoplankton feeding efficiencies, using 6-h incubations. Although healthy M. digitata consumed from 72% to 87% more pico-nanoplankton cells than P. lutea, feeding rates of bleached corals of both species were similarly low at heat stress (33 °C). Heterotrophic carbon acquisition with respect to dark respiration varied from 3% to 65% in M. digitata and from 7% to 68% in P. lutea. A decrease in the feeding efficiency of bleached M. digitata under heat stress shows its vulnerability to water heating events. Feeding rates of P. lutea were low under all conditions and treatments; therefore, this species is less vulnerable to heat stress due to the strategy of meeting metabolic costs by using translocated organic matter from endoliths and selecting pico-nanoplankton cells with a high C/N ratio. •Pico-nanoplankton feeding was assessed in two scleractinian corals from Okinawa.•Heterotrophy is important in recovery from prolonged bleaching events.•Bleached Montipora digitata under heat stress dramatically decreased feeding rates.•Bleached Porites lutea corals under heat stress prefer a diet with a high C/N ratio.•Porites lutea is relatively resistant to prolonged bleaching events.