Primary productivity of a degraded coral reef Joost den Haan  Petra Visser  Hannah Brocke  Mark Vermeij  Jef Huisman Session 26: Regime shifts in lakes, rivers and oceans

Nice reef

Reefs of Buoy 0 have been degrading rapidly… Bak et al. 2005

Which reef phototrophic organism contributes most to the overall productivity of the reef?

Reef organisms studied 5 macroalgal species Dictyota Lobophora Dichotomaria Halimeda Cladophora turf algae 1 coral species Madracis 2 cyanobacterial mats Lyngbya Dichothrix phytoplankton

Primary productivity: Benthic 13C 3-h incubation

Primary production: Phytoplankton Reef 13C 3-h incubation

Primary productivity results 5 m: light color 20 m: dark color 8 Tukey HSD a b bc bcd cd d Primary productivity (mg C g-1 DW h-1) 4 Madracis Turf algae Halimeda Cladophora Dictyota Lobophora Dichotomaria Dichothrix Lyngbya Lyngbya majuscula Plankton coral turf macroalgae cyanobact. phyto What is the areal productivity (per m2)? Biomass on the reef Primary productivity rates

Primary productivity at reef-wide scale Higher productivity at shallow reef phytoplankton turf algae macroalgae Primary productivity (mg C m-2 h-1) coral 5 m depth 20 m

Unique historic baseline Reef productivity 1975 vs. 2013 Is there a change in which organism contributes most?

Turf algae and macroalgae Change in organism that contributes most in the shallow reef?   Turf algae and macroalgae Hard corals Total PP mg C m-2 h-1 1975* 19% 65% 265 2013** 79% 16% 240 * Wanders JBW. 1976. The role of benthic algae in the shallow reef of Curaçao (Netherlands Antilles). I: Primary productivity in the coral reef. Aquatic Botany 2: 235-270. ** this study

Dissolved organic carbon Consequences Pathogenic microbes Dinsdale et al. 2008; Nelson et al. 2013 Coral diseases Barott et al. 2009, 2012 Dissolved organic carbon Turfalgae Haas et al. 2010,2013; Brocke et al. 2015

Thank you for your attention! Special thanks to my students: Laura Weiand, Anna Simeon, Amanda Ford, Katy Davis, Elfi Gooren, Anjani Ganase, Nienke ten Brinke, Moriah Sevier, Friso Dekker, Henry Goehlich, Jelmer Pander, Kelly Latijnhouwers, Seth van Heeringen, Saskia Honcoop, Tanja Bleyenberg, Ramona Brunner, Maureen de Wit, Milo de Baat, and Daan Mes