Environmental Engineering Reference
In-Depth Information
that occur over much shorter time spans. For this reason Mumby (2006) developed
a second model to parameterize parrotfish grazing intensity, in which he determined
the proportion of area grazed within a 6-month period. The calculations incorporate
parameters for fish species, abundances, sizes, sex, and feeding activity (bite rates).
According to the results, in an unharvested parrotfish community 30% of the total
area was grazed, while in heavily depleted populations the grazed proportion com-
prised only 10% and for areas of intermediate fishing pressure, this fraction amounts
to 20%.
The main model included corals, algae, urchins and parrotfish (Fig.
17.5
).
However, urchins were excluded from most model scenarios since a large scale
recovery of
D. antillarum
populations was considered unlikely and outbreaks of
diseases could readily reoccur. Corals and algae (see Table
17.1
for summary of
attributes for corals and algae) were placed randomly on the grid until distinct
Fig. 17.5 Processes included in the simulation model (
arrows
) that link the major functional
categories of reef organisms (
boxes
). Taken from Mumby (2006)
