Assessment of the Condition of Coral Reefs off the Former Navy Bombing Ranges at Isla De Culebra and Isla De Vieques, Puerto Rico

摘要

The impact of military exercises at insular bombing ranges on adjacent coral reefs has not been convincingly established. Some investigators imply widespread and catastrophic damage to reef organisms from errant ordnance, while others suggest that military zones create a de facto sanctuary from deleterious human activities such as coastal development, deforestation, and overfishing. This study documents the condition of fringing coral reefs in military and non-military areas, using the Puerto Rican islands of Culebra and Vieques as models. Historical records of military training and civilian use were reviewed in order to designate study sites as one of three types: civilian, military target, and military non-target. A total of 18 study sites were evaluated for biotic and environmental parameters. Proxy indicators of reef condition included percent coral cover, coral species richness, juvenile coral abundance, topographic complexity, fish species richness, fish abundance, herbivorous fish abundance, echinoid abundance, macroalgae cover, turf algae cover, incidence of coral diseases, and incidence of coral bleaching. To examine the relative condition of fringing reefs at Culebra and Vieques, we combined a Bray-Curtis distance measure with an Unweighted Pair Group Method with Arithmetic Averages (UPGMA) linkage method to perform a cluster analysis of the proxy indicators and to generate associated dendrograms (Sneath and Sokal 1973; McCune and Mefford 1999).