Physiological and biogeochemical traits of bleaching and recovery in the mounding species of coral Porites lobata: implications for resilience in mounding corals

PLoS One. 2013 May 2;8(5):e63267. doi: 10.1371/journal.pone.0063267. Print 2013.

Abstract

Mounding corals survive bleaching events in greater numbers than branching corals. However, no study to date has determined the underlying physiological and biogeochemical trait(s) that are responsible for mounding coral holobiont resilience to bleaching. Furthermore, the potential of dissolved organic carbon (DOC) as a source of fixed carbon to bleached corals has never been determined. Here, Porites lobata corals were experimentally bleached for 23 days and then allowed to recover for 0, 1, 5, and 11 months. At each recovery interval a suite of analyses were performed to assess their recovery (photosynthesis, respiration, chlorophyll a, energy reserves, tissue biomass, calcification, δ(13)C of the skeletal, δ(13)C, and δ(15)N of the animal host and endosymbiont fractions). Furthermore, at 0 months of recovery, the assimilation of photosynthetically acquired and zooplankton-feeding acquired carbon into the animal host, endosymbiont, skeleton, and coral-mediated DOC were measured via (13)C-pulse-chase labeling. During the first month of recovery, energy reserves and tissue biomass in bleached corals were maintained despite reductions in chlorophyll a, photosynthesis, and the assimilation of photosynthetically fixed carbon. At the same time, P. lobata corals catabolized carbon acquired from zooplankton and seemed to take up DOC as a source of fixed carbon. All variables that were negatively affected by bleaching recovered within 5 to 11 months. Thus, bleaching resilience in the mounding coral P. lobata is driven by its ability to actively catabolize zooplankton-acquired carbon and seemingly utilize DOC as a significant fixed carbon source, facilitating the maintenance of energy reserves and tissue biomass. With the frequency and intensity of bleaching events expected to increase over the next century, coral diversity on future reefs may favor not only mounding morphologies but species like P. lobata, which have the ability to utilize heterotrophic sources of fixed carbon that minimize the impact of bleaching and promote fast recovery.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Anthozoa / metabolism
  • Anthozoa / physiology*
  • Conservation of Natural Resources
  • Geology*
  • Pigmentation*

Grant support

This work was funded by the National Science Foundation divisions of Biological Oceanography (Grant No. 0542415) and Chemical Oceanography (Grant No. 0610487) (http://www.nsf.gov), the Mellon Foundation (http://www.mellon.org), and the Ford Foundation Diversity Fellowship (http://sites.nationalacademies.org/pga/fordfellowships/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.