Nearshore > Locations > Rota > Talakhaya

Within the Talakhaya watershed lie some of CNMI's very rare fresh water streams which discharge onto the adjacent reef flats. These coral reefs, like many others around the world, are adapted to clean, freshwater discharge. Unfortunately, polluted (brown) runoff originates from illegal burning by poachers that hunt deer in the Talakhaya watershed. Burning results in the exposure of barren soils (see picture) which are easily eroded during a rain event, and wash down to the ocean. The brown runoff has several negative effects upon coral reef communities, three important ones are listed below.

1) Direct burial of corals and other sessile (non-moving) organisms by sediment particles.

2) Blocking of sunlight penetration. Corals and many other reef organisms need sunlight to photosynthesize. Murky water decreases the amount of energy that the sun can deliver to these organisms.

3) Sediment particles have nutrients attached to them which "fertilize" nearby waters. Oceanic waters where coral reefs exists are usually oligotrophic (nutrient poor) which is why we can see the beautiful reef structures when we look from high above. Increased nutrients allow millions of phytoplankton (tiny single cell algae) to bloom. This bloom creates murky water and blocks the sunlight from reaching the corals (similar to #2 above). When these millions of tiny phytoplankton die and settle on the coral reef, their decaying bodies provide excess nutrients (fertilizer) to help macroalgae grow. This is not good because it allows the macroalgae to outcompete the corals for space on the reef. This photo shows parital burial of a Pavona bipartita coral colony and encroachment by the macroalgae Chlorodesmis fastigiata.

Re-vegetation and community awareness efforts will soon start in the Talakhaya watershed. This will consist of planting appropriate vegetation that will hopefully stabilize the barren soils. Community awareness efforts aim to establish a group of landowners and concerned citizens who are against illegal burning practices, and will establish a community based enforcement policy. For more information contact the DEQ non-point source pollution program.

Two graphs (see below) that illustrate a few trends that the marine monitoring team has found out in the past four years are presented.

This benthic cover graph shows that turf algae dominate the substrate on the reef slopes at Talakhaya. The photo behind the graph shows a typical scene on these reefs (turf algae, the macroalgae Asparagopsis taxiformis, and few corals). Over the past four years we have seen a slight decrease in coral and coralline algae, and a slight increase in macroalgae and "filter feeding organisms" (other invertebrates). Our monioring program will serve to evaluate the hopeful success of revegetation efforts, and provide the public with knowledge about their reefs.

This invertebrate abundance graph shows a sharp decline in the grazing urchin population, while sea cucumber and clam numbers remain relatively stable. The photo behind the graph shows a grazing urchin, Echinometra mathaei, previously common to these reefs. The decline may or may not be a natural population cycle, but the result is that when grazers are removed turf, macroalgae, and other invertebrates can increase in abundance (see above benthic cover graph).

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