The branching coral Madracis mirabilis
occasionally forms large thickets. These assemblages can be
well over 500m2. The architecture of these branching corals leads
to sediment falling out between their branches. Any structure in
the path of water flow will slow down the water flow, thus increased
the amount of sediment trapped between the branches. Over time,
this process starts burring the corals. These in turn keep growing
and as long as the growth rate outruns the sedimentation rate the
reef continues to grow.
dominated by M. mirabilis, Porites porites is another common
branching species interspersed in these ologi-specific aggregations.
The largest and most impressive ones run perpendicular to the shoreline
near Mero where individual ridges reach dimensions of up
to 1000 m2. The local dive site where these reefs are found is called
Maggie's Point. Smaller formations are found throughout the west
coast where reef accretion has take place. At Cachacrou (Scott's
Head) only a few remnants of large formations of this kind are alive,
due to the heavy use of this reef. In 2007 our survey team also
identified small patches of up to approx. 25m2 in the southern region
of Dominica near Fond Saint Jean.
2005 bleaching episode severely affected the abundance of P.
porites, which in 2006 had virtually disappeared from many sites.
This was also very evident in the M. mirabilis assemblages,
previously containing substantial amounts of P. porites.