We learnt a little about coral bleaching at the AquaVet II course during June this year. It’s not an unnatural phenomenon, and the coral are simply swapping the algae that lives within them with a different type to survive an environmental change. But sometimes this doesn’t happen as planned, perhaps because the right replacement algae doesn’t come along at the right time? Without their symbiotic algae, the coral polyps may eventually starve to death, leaving behind bare coral skeletons. Much research on the mechanisms of bleaching and recovery is being done.
But is coral bleaching as bad as we think? This study reports findings that are quite the contrary.
I’m interested to hear your thoughts.
assemblages: An experimental studySaleh A.S. Yahyaa, b, Martin Gullströma, c, d, 
, 
, Marcus C. Öhmana, Narriman S. Jiddawib, Mathias H. Anderssona, Yunus D. Mgayae, Ulf Lindahlf
| a | Department of Zoology, Stockholm University, SE-106 91 Stockholm, Sweden |
| b | Institute of Marine Sciences, University of Dar es Salaam, P.O. Box 668, Zanzibar, Tanzania |
| c | Department of Systems Ecology, Stockholm University, SE-106 91 Stockholm, Sweden |
| d | Department of Marine Ecology – Kristineberg, University of Gothenburg, SE-S-451 78 Fiskebäckskil, Sweden |
| e | Department of Aquatic Sciences and Fisheries, University of Dar es Salaam, P.O. Box 60091, Dar es Salaam, Tanzania |
| f | Blekinge County Administration, SE-371 86 Karlskrona, Sweden |
Received 30 August 2010; Accepted 25 April 2011. Available online 23 May 2011.
Abstract
Degradation and mortality of corals is increasing worldwide and is expected to have significant effects on coral reef 
fish; hence studies on these effects are essential. In the present study, a field experiment was set up within Mafia Island Marine Park in Tanzania (East Africa) to examine the effects of bleaching and habitat structure on colonisation of coral reef fish assemblages. Live and bleached staghorn coral Acropora formosa was transplanted onto plots in a site dominated by sand and rubble, and the experimental design comprised of three treatments: live coral, bleached coral and eroded coral rubble. There was an immediate increase (within 24 h) in fishabundance and diversity in the two treatments with standing corals. Overall, live and bleached coral plots showed similar effects, but differed from the eroded coral plots which had a much lower abundance and diversity of fish. In general, fish species diversity changed with time over the study period while fish abundance did not. Multivariate analyses showed that while there were differences in fish assemblage structure between standing corals and the eroded coral treatment, there was neither a difference between live and bleached coral treatments nor any temporal effects on fish assemblage structure. Our findings suggest that physical structure and complexity of habitat have stronger effects on colonisation of reef fish assemblages than changes in coral health (such as bleaching) which do not affect coral structure. This may have important implications for appropriate coral reef management.
Highlights
► We studied effects of coral bleaching and degradation on reef fish assemblages. ► Fish abundance and diversity were lower in eroded plots compared with standing corals. ► Fish species diversity showed temporal alterations, while fish abundance did not. ► Habitat complexity affected colonisation of reef fish. ► Coral health (bleaching) showed minor effects on colonisation of reef fish.
Keywords: coral reefs; fish communities; habitat degradation; disturbance; field experiment; resilience
View full article here:
;
—
Follow me on: Facebook “Fin Page” – YouTube – Blog – Linkedin – Twitter
Dr Richmond Loh
http://www.thefishvet.com.au
Ph: +61 (0)421 822 383
