A Survey on Black Band Disease in Bermuda

Discussion:

The temperature data collected is not the ideal method since temperature affects coral reefs in a larger temporal scale. The method that was used here was a temperature reading the time of the study. The readings may not have been an accurate representation of what each site experiences. Many factors like El ninos would cause a misrepresentation of temperature data taken from one point in time. Even though temperatures have warmed over the past century, there are still oscillations and dips in the data. Covering more of a time frame in temperature collection in Bermuda would represent more accurately what may be affecting the reefs.

Not all the disturbances are known for each site. Other disturbances might be causing the differences in percentages since wave action and temperature do not correlate with the presence of BBD at any of the sites. Water quality was not evaluated at the sites so perhaps this plays a stronger role. Acidification is known for playing an important role in coral health decline. Wave action does impact it somewhat but not significantly since the p-value is 0.082. Larger scale data on these abiotic factors would help us understand what causes the presence of BBD at the different sites in Bermuda coral reefs.
All sites were found to be impacted by BBD. Analyses found John Smith's have different percents of brain coral affected by BBD compared to Whalebone Bay and Causeway but not with North Rock. John Smith's has a high wave action and hurricanes affect this area. There is even evidence of debris still left over from the last hurricane. Hurricanes can leave the area vulnerable to disease for many years after the actual event. This site may be similar to North Rock since it has the highest wave action which may stress corals causing them to be vulnerable. The similarity found between the two sites is not conclusive since the method used for North Rock was not the same as the other sites. (Picture: coral at North Rock)

Causeway and Whalebone show similar percentages. However, much less coral was sampled at the Causeway site than Whalebone. The Causeway beach may have had less brain coral since the area is mostly populated by algae since the water is mostly stand-still. The water was very shallow so it probably reaches high temperatures on some days. Runoff from the Causeway and the airport may cause pollution contamination. More mustard corals were found since this species can handle more stress than brain corals. Less brain coral was found in front of the rock at Whalebone. The water moved very slowly in this area since the rock may act like a barrier decreasing coral recruitment in this area. The conditions at the Causeway beach may have been so different from the other sites that any analyses to compare sites may be difficult.                                                                                                                 

                                                                                                                                                View of Bermuda on boat ride to North                                                                                                                                                      Rock

This survey in Bermuda is important to understand what actually triggers BBD. The knowledge of knowing the differences of the intensity of outbreaks can help us evaluate what causes a higher outbreak. It may be a collection of abiotic factors like pollution and high acidity and not just one. Longer term data should be used like the BIOS monitoring data to make a complete evaluation of how these factors impact coral health.