Science Wednesday: Underwater Science
Each week we write about the science behind environmental protection. Previous Science Wednesdays.
About the author: Bill Fisher has worked with EPA’s Office of Research and Development for 18 years. His academic research included environmental studies of several marine invertebrates, including lobsters, crabs, squid and oysters. For the last five years he has worked to improve environmental protection of U.S. coral reefs.
This will be our third survey of coral reefs in the U.S. Virgin Islands (USVI). The first was in St. Croix where we verified that a new EPA bioassessment method could identify adverse effects of human activity on coral reefs. The next year we applied an Environmental Monitoring and Assessment Program (EMAP) ‘probability-survey’ method to determine the condition of reefs island-wide. And now, another year later, we will perform the same survey at St. Thomas and St. John.
It may seem a long time to complete a study, but coral reef research has many challenges—not the least of which is a suitable ship to work from. EPA has a well-equipped research ship, the Ocean Survey Vessel BOLD. She not only provides us berth and board, but has compressors to fill our SCUBA tanks and dive boats that we deploy to our sampling locations. The OSV BOLD is in great demand, so it is fortunate that we are able to work from her even once a year.
The survey itself is not complicated—especially if you were to run it on dry ground. The coral surveyor identifies each coral colony in a 25 square meter transect, measures their size and estimates the percent of live tissue. (Corals are clonal organisms, and colonies can suffer large losses of living tissue without dying). Under water, these observations are more difficult because the surveyor has to maneuver in currents and surge. What’s important is that these three basic underwater observations provide several indicators highly relevant to resource management.
We usually field three dive teams and each surveys two to three stations a day. All too often, it is too windy or there are high rollers (waves) that pose hazards getting in and out of small boats with dive gear. On these days we usually catch up entering data, checking gear and reading emails.
Our ultimate purpose in USVI is to assist in the development of coral reef biocriteria. These are water quality standards developed from indicators of coral condition. The first survey we ran told us that we could use the new bioassessment procedures, and the latter two will establish the baseline condition for coral reefs. USVI will use this baseline condition to establish expectations for reef health in the future.
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