Reserve CEBSE, 1993a, but this was never acted on by the national Biosphere Reserve Committee.
The Sabana de la Mar-Nisibón coastal plain lies further to the west on the southern side of the Bay. This area is distinguished by its numerous fresh and brackish water lakes and
wetlands and contains the Redonda and Limón Lagoon biological reserves. Monitoring in the Bay during the period 1988-89 showed temperatures in the Bay
between 25-32 degrees Celsius, pH between 7.7 and 8.5, and salinity in western part of the between 0-25 percent CEBSE, 1993a. The waters in the western end of the Bay showed levels
of total and dissolved organic material of 183 mgL and 88 mgL, and an average concentration of soluble phosphate of 6.19 mgL.
Studies of zooplankton, also during 1988-89 show an abundance of organisms. The average density of zooplankton was 60,000 org m
3
, with a maximum of 150,000 org m
3
CEBSE, 1993a. The most productive areas are the mouths of the Barracote River and the coast of Los Haitises.
3.2 Freshwater Flow and the Ecology of the Samana Estuary
The ecology of mangrove and other estuarine communities of the Yuna-Samana Bay estuary are dependent on freshwater flows see Figure 5. Alteration to the freshwater flows of the
Yuna River and tributaries and associated salinity regime changes in the estuary has probably had extensive effects on the mangrove and estuarine community, such as loss of mangrove integrity,
increasing sedimentation, and decreasing commercial fish catches. The mangrove swamp becomes more saline in the low flow period due to evaporation and saltwater intrusion. Evidence
of change within the Bay include “shallowing” at the southern extent. During our field reconnaissance the fishermen who took us around the Bay attempted to get the boat in places that
used to be open to shallow draft boats. This was all but impossible for us on this trip. Mud was churned up in areas that should from a geophysical pint of view, naturally be much deeper.
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Reduced flows create an environment conducive to changing species dominance and zonation. Mangroves form distinct zones of species that reflect the salinity and topography of the
surrounding environment. The duration and volume of freshwater flows and the salinity of tidal waters affect soil conditions and vertical stratification within the water column which determine
the distribution of species within mangrove communities. Changes in the balance of fresh and marine waters may lead to increasing anoxicanaerobic benthic conditions, decreased nutrient
inputs, increasing sediment loads, increasing erosion, and upstream migration of the salt-wedge and the problems typically associated with this movement.
It is thought that mangrove zonation found at the mouth of the Yuna and Barricote Rivers in Samana estuary is changing in response to salinity and freshwater flow alteration. There is
anecdotal evidence to support this “observed” change as well as range expansion upriver. The changing diversity and zonation in these mangrove communities may impact habitat for river and
estuarine species and nursery grounds critical to viability of many commercially important species. Also, changes in mangrove systems, which contribute to the stability of coral reefs and
sea grass beds by protecting them against sedimentation and associated turbidity, may permanently alter the non-estuarine food web found in Samana Bay.
4. Water Dependent Sectors and Resource Use in the Watershed
