Coral reef ecosystems are disturbed in tandem by climatic and anthropogenic stressors. A number of factors act synergistically to reduce the live coral cover and threaten the existence of reefs. Continuous monitoring of the coral communities during 2012–2014 captured an unprecedented growth of macroalgae as a bloom at Gulf of Mannar (GoM) and Palk Bay (PB) which are protected and unprotected reefs, respectively. The two reefs varying in their protection level enabled to conduct an assessment on the response of coral communities and their recovery potential during and after the macroalgal bloom. Surveys in 2012 revealed a live coral cover of 36.8 and 14.6% in GoM and PB, respectively. Live coral cover was lost at an annual rate of 4% in PB due to the Caulerpa racemosa blooms that occurred in 2013 and 2014. In GoM, the loss of live coral cover was estimated to be 16.5% due to C. taxifolia bloom in 2013. Tissue regeneration by the foliose and branching coral morphotypes aided the recovery of live coral cover in GoM, whereas the chances for the recovery of live coral cover in PB reef were low, primarily due to frequent algal blooms, and the existing live coral cover was mainly due to the abundance of slow-growing massive corals. In combination, results of this study suggested that the recovery of a coral reef after a macroalgal bloom largely depends on coral species composition and the frequency of stress events. A further study linking macroalgal bloom to its specific cause is essential for the successful intervention and management.
While numerous strategies have been used to educate and notify the public about potential hazards from exposure to Harmful Algal Blooms (HABs), at present there are no national guidelines or suggested outreach approaches. To raise public awareness and determine effective HAB outreach methods, two Washington State agencies and three counties in the Puget Sound region implemented several education and notification strategies. These approaches were rated for effectiveness by state and county public health and water quality professionals. At the state level, the most effective action was a three-tiered advisory posting protocol for notifying external users that was introduced to local health jurisdictions at workshops around the state. Supplemental permanent signage is recommended for lakes with blooms to overcome the time lag between HAB onset and testing/posting. The state also implements effective notification of toxicity test results through a web-based HAB database and listserv. Lake residents were best notified through electronic alerts including email and social media while mailers to lake residents were useful during initial HAB events and to gain subscribers to electronic alerts. Press releases were most valuable when used sparingly for severe blooms or for blooms in large lakes. Initial analyses of lake recreational use indicates these strategies encourage behavior change in lake users. Based on these findings, a general framework for HAB outreach and a specific notification strategy is proposed to assist other regions or agencies that are developing HAB education and notification programs.
Blooms of the green macroalga Ulva prolifera in the western Yellow Sea occurred every year since 2008, and they have been reported and studied extensively using a variety of means including remote sensing. However, to date, long-term bloom patterns have not been reported except for a few case studies showing examples in different years. Here, using MODIS observations and an objective method to perform statistical analysis, mean Ulva coverage in the western Yellow Sea has been derived and analyzed between 2007 and 2015 at both monthly and annual scales. On annual scale, mean Ulva coverage decreased after 2008, but increased rapidly after 2012 from 8 km2 in 2012 to 116 km2 in 2015 (the largest ever reported in history for this region). In the month of June the mean coverage increased from 18 km2 in 2012 to 363 km2 in 2015. Other than 2009 and 2010, the month of June showed maximum Ulva coverage in every year. These coverage estimates are significantly lower than previously reported values as they represent “pure” algae coverage after taking into account of partial pixel coverage. Several environmental factors were examined in an attempt to determine the reasons behind such long-term changes, yet the results are inconclusive, suggesting a strong necessity of further coordinated and multi-disciplinary researches.