Publisher :
Place of publication :
Publication year : 2008
Thematic : Marine Resources
Language : English
Note
The Saipan Lagoon (Northern Mariana Islands) was first examined for benthic composition
and habitat distribution in the late 1940s. Here, we employ a 4-stage approach to evaluate and
explain change in the distribution of the 9 habitats previously demarcated. We show that there have
been considerable reductions in seagrass, staghorn Acropora, and Acropora palifera dominated habitats
(–3.72, –1.26, and –1.37 km2, respectively) that were replaced by 6.16 km2 of sand (~20% of the
lagoon area). Multiple regressions showed that the spatial extent of Enhalus seagrass was positively
related with, and best predicted by, the adjacent watershed area and lagoon width. Although the
interaction was not as strong, Enhalus also increased in accordance with human development. The
size of the Halodule seagrass and macroalgal habitat was negatively related to water-flow velocities
and positively related to human development, while its integrity (i.e. the density of seagrass within a
given habitat) decreased with human development. Taken together, the results suggest Enhalus and
Halodule respond differently to proxies of watershed pollution, and contradict contemporary doctrine
linking pollution with reduced seagrass density. This study found no relationship between offshore
habitats and watershed characteristics, but suggests their expansion and contraction on relatively
short time scales is a result of large-scale disturbances such as typhoons. We posit that, while habitat
integrity can be altered by human disturbances, habitat identity is only altered under extreme conditions.
In summary, this study advances habitat mapping by increasing resolution and accuracy,
which, in turn, improves the texture at which reef ecology is used by management.
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Keywords : coral reef
Encoded by : Pauline Carmel Joy Eje
