Benthic Community Recovery from Small- Scale Damage on Marginal Caribbean Reefs: an Example from Panama

The frequency of small-scale physical damage to coral reefs is likely to increase as fishing and tourism pressures intensify. Predicting how reefs will respond to the effects of these types of damage requires empirical exploration, especially on reefs that are already heavily degraded. We replicated small-scale damage on four reefs that live close to their ecophysiological tolerance limits in the Bocas del Toro Archipelago of Caribbean Panama and quantified their recovery over 2 yrs. On each reef we cleared five replicate 1 × 1-m plots of all living benthos simulating physical damage by boat grounding, anchoring, or fishing practices. Recovery of the benthic community was quantitatively monitored and compared to adjacent non-cleared plots (treated as a control) every 6 mo. After 2 yrs, only one of the reefs exhibited evidence of recovery of the cleared plots. Poor recruitment of benthos appeared to slow down recovery of cleared plots on another reef. The other two reefs showed unequivocal shifts toward a macroalgae-dominated system, suggesting that smallscale disturbances could have lasting impacts on marginal reefs. We found no clear contemporary or historical environmental signal that could explain the differential dynamics of recovery amongst these reefs. Reefs are frequently affected by destructive maritime activities such as fishing, boat grounding, and the collection of aquarium goods and building materials. These practices are increasing globally (Aronson and Swanson 1997, McManus et al. 1997, Guzman and Guevara 1998, Rützler 2002, Moulding et al. 2012) and not only destroy reef architecture and kill benthos, but also increase the amount of bare substrate available for colonization by organisms other than coral (Hughes 1994, Connell 1997, McManus et al. 1997, Precht et al. 2001, Dudgeon et al. 2010, Moulding et al. 2012). This may be more manifested on Caribbean reefs that show severely altered baselines (Hughes 1994, McClanahan et al. 1999, Gardner et al. 2003, Pandolfi et al. 2003, Mumby et al. 2007, Knowlton and Jackson 2008). Large-scale damage to reefs, for example, by hurricanes, destroys swathes of reef architecture, and recovery is dependent upon the viability of recruitment and distance from other, less damaged reefs (Dennis and Bright 1988, Knowlton et al. 1990, Hughes 1994, Aronson and Swanson 1997, Lirman 1999, Hughes et al. 2003). The recovery of small-scale damage, on the other hand, is probably much more limited by the health and recruitment potential of the reef surrounding the damaged patch (Bonin et al. 2011). Therefore, it is likely that reefs that are living close to their ecophysiological tolerance limits will respond unfavorably to small-scale damage. A patch of reef that has been cleared by disturbance can follow one of three possible trajectories: (1) full recovery back to the original community, (2) failure to recover, or (3) a shift towards an alternative state (Bellwood et al. 2004, Knowlton 2004, Rogers and Miller 2006, Norström et al. 2009). Of the latter, the shift to <<PLEASE