Environmental effects on coral growth and recruitment in the Caribbean

Knowledge about factors that are important in coral reef growth help us to understand how reef ecosystems react following major anthropogenic and environmental disturbances. In addition, they may help the industry understand how aquarists can improve the health of their corals. I have studied environmental and climate effects on corals on fringing reefs in Jamaica. Radial growth rates (mm/yr) of non-branching corals calculated on an annual basis from 2000–2008 showed few significant differences either spatially or temporally along the north coast, although growth rates tended to be higher on reefs of higher rugosity and lower macroalgal cover. I have also reconstructed recruitment patterns, using growth modelling, for non-branching corals at sites on the north coast of Jamaica near Discovery Bay, and near Kingston Harbour, on the south coast. For all the sites, recruitment of non-branching corals was lowered due to hurricanes or severe storms. For 1560 non-branching corals at sites along the north coast of Jamaica, from Rio Bueno to Pear Tree, there was a significant difference in estimated coral recruitment in years when there were no storms or hurricanes by comparison to years when storms and hurricanes impacted the area. For 347 non-branching corals at sites in the Port Royal Cays on the south coast, there was a significant difference in estimated coral recruitment in years when there were no storms or hurricanes by comparison to years when storms and hurricanes impacted the area. Interestingly, recruitment of Siderastrea siderea on to the side of the ship channel at Rackham's Cay (~100 m from the path taken by large ships) outside Kingston Harbour had been consistent since its construction. These findings have important implications for better understanding the impacts of tropical storms on coral reefs and for aquarists to better maintain coral reef species in artificial environments.

Spatial distribution of surficial sediments in part of the Kingston basin of northeastern Lake Ontario, Canada

The distribution of surficial sediments in the interisland area of northeastern Lake Ontario is characterized by a generally homogeneous composition of fine grained muds with some local exceptions at the gaps leading into Kingston basin and in parts of North Channel. This pattern reflects principally differing levels of wave energy from the exposed areas of outer Kingston basin and Upper and Lower gaps to the more protected interisland area. Additional processes responsible for the distribution are currents at the Upper and Lower gaps and local slumping. The observed deposition of surficial sediments in the northern Kingston basin shows generally good agreement with the wave base calculations employing wind speeds of 60 km·h-1. The study region consists of three sedimentary environments. Above the wave base related to winds of less than 60 km·h-1 continual erosion and transport of all grain sizes leads to a constant source of sediment to the deeper parts of the Kingston basin. Above the wave base related to infrequent strong winds of more than 60 km·h-1, episodic removal of the fine grain sizes leads to winnowing of the fines and their being transported into North Channel and Kingston Harbour while the sands are left in place. Below the wave base the sediments are undistributed. Thus, there is no proximal-distal differentiation outward from the coasts nor along the channels. The sediment is transported with currents moving through North Channel and Kingston Harbour with similarly low velocities across the entire section.