The Lagoon
Mangrove forests, marine, estuarine and freshwater aquatic habitats of Placencia Lagoon provide habitat and ecosystem services to literally thousands of species of organisms. Unfortunately, pressure from human activities has taken a toll on this unique ecosystem and threatens to impair many of these populations and the functions they provide.
Placencia Lagoon provides a sheltered environment where adult marine mammals animals like bottlenosed dolphins and West Indian Manatee can care for their young. The Southern Environmental Association (SEA) facilitates the work of international NGOs and universities to help monitor and study the distribution, behavior and ecology of marine mammals. The female above was captured, measured, and sampled during work by Wildlife Trust (photos by T.B. Smith).
The American crocodile and Morelet’s crocodile both live in Placencia Lagoon. Increasing human population density makes interaction between humans and crocodiles more likely and raises a host of concerns for both species (photo by T.B. Smith).
Terrestrial habitats around Placencia Lagoon support a dazzling array of unique plants and animals. Dozens of unique species of wild orchids grow in and around the mangrove forests of Placencia Lagoon. This flower, Myrmecophila tibicinis, is locally known as the "cow-horn orchid". It shelters symbiotic populations of ants that protect it from grazers. Untold species and unique biological interactions in Placencia Lagoon remain unknown and undocumented (photo by B. Collier). 
Over 70 species of fish have been identified in Placencia Lagoon including Goliath grouper (Epinepheus itajara) pictured above. Placencia Lagoon serves as an important nursery for juvenile fish and a transitional zone between fresh and salt water habitats (photo by T.B. Smith).
Food web studies supported by the Oak Foundation through the SEA have shown that seagrass supports the food web of fisheries in Placencia Lagoon as both a carbon source and habitat. Unique seagrass species, including Halophilla baillonii (pictured here) have been found in the lagoon and shown to be a major diet item of West Indian Manatee (photo by T.B. Smith). 
In this graph, the correspondence between values of delta-13C in food sources and fish tissues are shown. Most major sport fish and commercial species align more closely with seagrass food sources, showing their importance as the base of the food web supporting the lagoon fisheries. (graph by T.B. Smith).
One of the major limiting factors for seagrass in shallow coastal lagoons is water clarity. The graph above shows the depths of cores with and without seagrass in a coastal lagoon in Belize. Clear water allows penetration of light to the lagoon bottom which in turn allows growth of seagrass. Nutrients that increase suspended algae (seston or phytoplankton) and algae growing on seagrass blades (epiphytes) blocks out light and smothers seagrass. Suspended sediment from wave activity, denuded shorelines or human activity can play a similar role (graph by T.B. Smith).
Shrimp Aquaculture
The majority of Belize's shrimp aquaculture industry is located in the Placencia Lagoon area. Effluent from ponds affects lagoon water quality by adding nutrients and sometimes organic pond sediments. The graph above shows the typical effect of turbidity in a coastal creek downstream from a shrimp pond being drained. The lagoon processes most of these nutrients before they are released to the sea. Shrimp farmers in the Placencia area are currently adding a variety of mitigations to reduce effects of their effluents on the lagoon itself as well as points offshore (graph by T.B. Smith). 
Shrimp farms in Belize take coastal waters to grow their shrimp and then release effluents from production ponds back into the sea. Nutrients from feed and fertilizers are added to pond waters to enhance shrimp growth. Fringing mangroves are often used to help mitigate impacts of effluent releases. Half of the 20 shrimp farms that have been started in Belize have ceased to operate due to global over-production of shrimp and low shrimp prices. In general, farms with fewer technical capabilities and lower stocking densities were more likely to fail (photo by T.B. Smith).
Most of the remaining shrimp production in Belize operates with a high technical capacity and environmental safeguards in place. The global shrimp dialouges sponsored by FAO, WWF, UNDEP, NACA and others have focused on Belize as a positive example of environmentally sustainable shrimp production (photo by E. Fernandez).
The universal popularity of the Caribbean seafront has resulted in rapidly increasing prices for coastal properties and widespread clearing of mangroves. Increasing human populations put increasing pressure on local infrastructure and creates additional waste and pollution that enters the lagoon and adjacent habitats. The loss of mangrove habitats represents a critical issue for ecosystems such as Placencia Lagoon (photo by T.B. Smith). Fisheries Conservation
Traditional and recreational sport fishing mingle in Placencia Lagoon. Tarpon, snook, goliath grouper, a variety of snapper and other species are targeted with gill nets and hook and line. Fisheries options will be needed that keep the quality of the resource high and sustainable for all stakeholders.
Juvenile silk, black, mutton, schoolmaster (above) and dog-teeth snapper live and grow in Placencia Lagoon. Studies are underway to understand the migration patterns of these fish. Inshore habitat may contribute significantly to offshore spawning aggregations of these species (photo by B. Collier).
Gill nets are illegal near creek mouths and within 3 miles of settlements. Unfortunately, they are still used extensively in Placencia Lagoon in areas where they are illegal. Tarpon, snook and bonefish suffer badly from this practice (photo by T.B. Smith).
Basic information about the organisms and ecology in Placencia Lagoon are needed to guide management decicions in the lagoon. Monitoring of fisheries, water quality and seagrass is needed on a regular basis. Support for scientific studies of the lagoon has been provided by a variety of foundations, private donors and SEA (formerly Friends of Nature and TASTE). Further support is needed to maintain technical capacity and provide support for biologists to monitor and study processes in the lagoon and along the coast (photos by T.B. Smith and B. Collier).
Restoration of critical habitats including mangrove and seagrass are needed in the lagoon. Current efforts are focusing on shrimp aquaculture outlets and areas under intensive development (photos by T.B. Smith).
Placencia Lagoon provides vital ecosystem services to the local economy and environment. Efforts are currently underway to designate the lagoon a special protected area. Under the auspices of a multi-use Marine Protected Area, scientific monitoring and continuing partnerships with local stakeholders can address problems as they arise to keep the ecosystem intact (photo by T.B. Smith).
If you would like to know more or you are interested in supporting conservation work in Placencia Lagoon, please contact: the Southern Environmental Alliance (sea.belize@yahoo.com) or Timothy B. Smith (t_brooksmith@hotmail.com).
