Evidence of a phase shift to Epizoanthus gabrieli Carlgreen, 1951 (Order Zoanthidea) and loss of coral cover on reefs in the Southwest Atlantic

Abstract

There is at present a ‘coral reef crisis’; one of the more drastic consequences of this is a phase shift, in which reef‐building corals are replaced by non‐reef building benthos such as macroalgae and soft corals. Previous studies have principally focused on the shift to macroalgae. Our goal was to investigate whether the dominance of the zoanthid Epizoanthus gabrieli on some reefs of Todos os Santos Bay, Brazil, represented a non‐algal phase shift. In 2003, we identified a high cover of this species on two reefs (52% and 70%), but only in 2007 was it possible to confirm a reduction in coral cover. This dominance has persisted for over 9 years, characterizing a true phase shift. This loss of coral cover may be a result of anthropogenic disturbances within the bay; however, given the large number of human impacts, further studies are needed to identify specific causes of this shift. Although there are some reports of phase shift involving species pertaining to the Class Anthozoa, this is the first report of this phenomenon involving the order Zoanthidea.

Ordinary kriging vs inverse distance weighting: spatial interpolation of the sessile community of Madagascar reef, Gulf of Mexico

“…Hard corals used to dominate the seascape of tropical reefs; however, their populations have declined in recent decades due to multiple disturbances such as overfishing, eutrophication and high temperatures ( Nyström & Folke, 2001 ), allowing other HFO to increase their abundance ( Nyström, Folke & Moberg, 2000 ; Wilkinson, 2004 ; Ruzicka et al, 2013 ; McMurray, Finelli & Pawlik, 2015 ). Many coral reefs are now dominated by macroalgae ( McManus & Polsenberg, 2004 ), with other reefs presenting high percentages of substrate covered by octocorals, zoantharians and sponges ( Norström et al, 2009 ; Cruz et al, 2015 ; Bell et al, 2013 ). Although there is uncertainty in the scientific community about the specific ecological changes that may take place in the future, it is very likely that changes will continue as global warming intensifies ( Bell et al, 2013 ; Gross, 2013 ; Ruzicka et al, 2013 ).…”

Interpreting coral reef monitoring data: A guide for improved management decisions

“…By cross-referencing those attributes suggested in Table 3 column 4, a user should be able to confirm which is the most likely driver of a trend. Box and Mumby, 2007;Kuffner et al, 2006Mumby, 1999Gilmour et al, 2013Jones et al, 2009;Sandin, 2008 Cortés andRitson-Williams et al, 2009 Coral cover Cruz et al, 2014;Kuguru et al, 2004;Muhando et al, 2002;Norström et al, 2009 Coral recruitment ↓ Mah and Stearn, 1986;Woodley et al, 1981 Coral recruitment ↑ Ehrhardt et al, 2011;Wynne andCôté, 2007 Ehrhardt et al, 2011;Wynne and Côté, 2007Ehrhardt et al, 2011Behringer et al, 2009 Conch ( Newman et al, 2006;Wilson et al, 2008 Gratwicke andSpeight, 2005;Wilson et al, 2008 Length by species Decrease Potential overfishing Fisheries data, slope of size-spectra Dulvy et al, 2004;Graham et al, 2005 Biomass Newman et al, 2006;Wilson et al, 2008 Gratwicke andSpeight, 2005;Wilson et al, 2008 Biomass Ault et al, 1998;McClenachan andKittinger, 2013 Burke, 1995;Mumby et al, 2004;Nagelkerken et al, 2000 …”

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“…), which also has contributed to extensive declines in coral populations (Cruz et al. , Loh and Pawlik ). Although it has been proposed that thermal stress is a driver of several coral diseases, we are just beginning to understand the environmental conditions that trigger coral disease outbreaks (Harvell et al.…”