Print PageClimate change is expected to increase the intensity and duration of hurricanes. Historically, coral reefs have benefited from hurricanes by increasing bio-diversity on the reef. However, with the anticipated increase in hurricane activity, the crucial question is ‘How will coral respond to changing patterns of hurricane activity?’
We study population data for the reef-building coral Montastraea annularis on Glover’s Reef, Belize. The study followed individual coral patches between June 1998 and January 2003, during which 3 hurricanes affected the reef. Primarily, damage resulted from Hurricane Mitch, a category 5 hurricane in November 1998, however, two smaller hurricanes, Keith and Iris, also affected the reef in September 2000 and October 2001 respectively.
We create three Integral Projection Models (IPMs) to assess the behaviour on the reef under three different conditions: No hurricanes, category 3-4 hurricanes and category 5 hurricanes. We use IPMs instead of PPMs because they are better able to accommodate size-structured populations; with no need to discretize size-class, there are smaller modelling errors. We parameterize our models by fitting distributions to survival, growth and fragmentation data. These IPMs are projected to explore the impact on population size and structure of several differing hurricane patterns: Clustered hurricanes versus periodic hurricanes; increasing hurricane intensity and combinations of clustering and increased intensity.
Results/Conclusions
We show that regardless of hurricane activity, the coral population is in long-term decline. This decline is greater as hurricanes are introduced to the system. With a given number of hurricanes over a given period of time, we find that it is advantageous if these hurricanes are clustered together. It is better for the health of the coral if there is a long period of recovery time between clusters of hurricane activity.
The increase in hurricane intensity has more impact on coral cover. On Glover’s Reef, only 2 category 5 hurricanes have disturbed the reef in the past 100 years. When the frequency of category 5 hurricanes is increased there is a greater decline in population size, compared to when smaller hurricanes are dominant.
Finally, we use the models to propose possible management strategies, which aim to increase the growth of the population in between hurricanes by adjusting the fitted parameters. This effectively reduces the time needed for the coral to recover to its pre-hurricane density.
