The Placencia Lagoon - Coastal Zone Management Authority and ...

Salinity
The salinity of the Southern Shelf Lagoon is affected on a seasonal basis by the
precipitation and river discharge in the southern province. The salinity of the Southern
Shelf Lagoon fluctuates range between 33 to 35 parts per thousand (Gibson et al., 1993).
The Importance of the Placencia Lagoon
Like most tropical and subtropical estuarine systems, the Placencia Lagoon has
ecological and environmental significance. The lagoon per se has a diverse amount of
planktonic life that makes it an ideal nursery ground for a myriad of marine and estuarine
organisms. Many of the fish that are caught for food or fun in the higher parts of the
estuary or within the Belize Barrier Reef complex depend on the Placencia Lagoon for
portions of their life cycles. Furthermore, the Placencia Lagoon provides adequate
ecological and environmental conditions for the endangered and threatened West Indian
Manatee (Trichechus manatus). The lower portion of the lagoon is relatively shallow
with extensive beds of seagrass Thalassia testudinum that these creatures feed on. In
close proximity to the lagoon are the mouths of several streams that are adequate source
of freshwater for the manatees to drink. The inner portions of the Placencia Lagoon have
areas that are completely protected from wind and wave activity that offer a safe and
tranquil resting place for adult manatees and their calves.
During the surveys, dolphins were sighted feeding in the middle and lower portions of the
Placencia Lagoon (Plate 1). Fishers from Seine Bight Village confirmed that dolphins
are sighted regularly throughout the year in the lagoon (pers. com., Javier Maritinez).
Morelet’s crocodiles (Crocodylus moreletii) are also a threatened species that have been
sighted in various parts of the Placencia Lagoon system. Platt et al. (1997) found no
evidence of nesting activity in the Placencia Lagoon however, spoil banks in the Maya
Beach area are considered potential nesting habitats. Grimshaw (2000) reported that the
Morelet’s crocodiles use the habitats in the lower reaches of the Placencia Lagoon for
nesting sites.
The vegetation fringing the lagoon supports nesting sites for several marine birds. Quite
frequently pelicans, gulls and bobbies are seen feeding in the lagoon and roosting on the
natural vegetation. In addition to this, the marshlands surrounding the Placencia Lagoon
serve as natural filters for sediment and pollutants. ESTAP (2000) report that the Mango
Creek Special Development Area Development Plan approved in 1997, identified the
need to protect the mangrove wetlands that surround the Placencia Lagoon. The intention
is to ensure that water quality in the lagoon, together with manatee and other wildlife, is
not negatively affected by inappropriate development. Some residents from Placencia and
Seine Bight in conjunction with organizations such as BTIA and Friends of Nature
express concern about the fate of the Placencia Lagoon.
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