Lau Lau Bay contains some of the most diverse yet threatened reefs in the entire CNMI. The protected nature of the bay has allowed thriving reefs to development over the past 5,000 years, resulting in amazing, three dimensional reef structure today (see photo below). This reef structure is valued by divers and fishermen alike because of its beauty and fish habitat that it provides. The protection and isolation of the bay also means that these reefs are more susceptible to disturbances (typhoons and pollution).

Upland burning and clearing for development, farming, and even hunting over the years has led to patches of exposed soil that only need a rainstorm to create "brown" runoff. See Talakhaya site for a more detailed discussion of "brown" runoff and its effects upon coral reef communities. If the sediment and nutrient runoff is not stopped, the community structure (arrangement of plants and animals) of the living reef will eventually change.

The CNMI Marine Monitoring Team has established two long-term sites since 2000 in Lau Lau Bay, however we have also collected historical data from surveys that were undertaken in 1983 and 1991. Unfortunately, the trends are not good for the bay. At both sites there has been a large decrease in coral community evenness (an even amount of all species of coral and not dominance by just one, or a few, species) (see figure below). Specifically, Lau Lau #2 site, known as the popular dive cut, shows the greatest loss of three dimensional corals (branching and massive) and an increase in Porites corals (seen overgrowing the Goniastrea coral in the photo behind the graph below). At Lau Lau #1 site, or the southern half of the bay, corals have been dying and giving way to macroalgae that do not provide structure to the reef or ideal habitat for fish and other ecologically beneficial organisms (see second and third graph).

The importance of coral diversity can best be understood using the common flu as an example. When a flu passes through our population not every individual gets sick because we are all different (we have a high diversity of genes). If we were all the exact same one disease could wipe out our entire population. On a coral reef different species respond differently to disease and disturbance. This is one reason why a beautiful, diverse reef has evolved in Lau Lau Bay over the past 5000 years. Recently, because of upland pollution we are decreasing coral diversity, and making the living community more uniform.

This is only one reason why biological diversity is important, diversity also creates habitats for animals to live (fish that we eat) and a beautiful site for our eyes. So it is extremely true that whatever we do on land can and does impact the ocean. Lau Lau Bay watershed restoration efforts that CRM and DEQ have or will soon start need public support and involvement for them to work. To learn more about these efforts contact the DEQ Non-point source pollution branch.

Benthic cover change at Lau #1 (above) and Lau #2 (below).

Looking for more indepth information? The marine monitoring program has more detailed information and reports available upon request.

Last updated 08 Sept. 2010 rc