Río Espíritu Santo, river which flows into the Atlantic Ocean through the municipality of Río Grande

Río Espíritu Santo, river which flows into the Atlantic Ocean through the municipality of Río Grande

Río Espíritu Santo Natural Reserve is an area of important coastal resources which is subject to conflicts of use. It consists primarily of a coastal valley within a flood zone in which various ecological systems converge. These include flooded lands (extensive mangrove, herbaceous and arboreal swamps) that are saturated by surface or ground water. In addition, it includes extensive Thalassia meadows, an extensive coral reef, and the estuary of the Río Espíritu Santo. This is the only river open to the ocean that may be navigated by small boats. The area is classified as a subtropical rainforest with an average annual rainfall of 1,973 mm (77 inches) and an average annual temperature of 26.6°C (79°F).

The zone can be considered an area of transition —an ecotone— between marine and terrestrial habitats; however, many of its most important physical and biological characteristics are non-transitional and unique to the area. This characteristic makes this a highly complex system where there are different vegetation communities which respond to numerous environmental factors.

Río Espíritu Santo Natural Reserve is located in the coastal plain of the municipality of Río Grande in the northeast sector of Puerto Rico, within the Río Espíritu Santo hydrographical basin. The reserve is bordered on the north by the Atlantic Ocean and on the south by Cerro Bravo and Highway 3, on the west by Road 187, and on the east by Punta Percha. The reserve covers approximately 4,892 acres. Of these, 2,483 are seafront acres, 918 acres are part of the land segment of Punta Picúa (east), and 1,491 acres belong to the Río Espíritu Santo segment (west).

Most soils in the reserve area are virtually flat with little topographical relief and are frequently or seasonally flooded during most of the year; they are mostly of low salinity. There are nine types of soils in the reserve and these offer limitations that vary from moderate to severe in terms of crop cultivation, from rocky to sandy and clay soils with little drainage and low permeability. The soil types that predominate are the tidal marsh, tidal plane, and damp alluvium.

The Río Espíritu Santo estuary is one of the most important resources the natural reserve has. The estuary is an aquatic ecological community characterized by the mix of freshwater from the river and seawater. This mixture is what is known as brackish water to which a large numbers of plant and animal species have adapted. As for fauna, estuaries serve a very important function as the mix of freshwater and seawater creates a nutrient trap.

Under heavy rain conditions, estuary waters become less salty, which favors freshwater species. On the other hand, by decreasing the input of fresh water, salinity increases and favors marine species. This high productivity is reflected in the large number and diversity of organisms that live there or use it.

Therefore, protecting the estuary is a very important factor in maintaining organism populations upstream: in the reef, the ocean, and of course in the estuary itself.

Ecological value
The reserve is considered an area of high ecological and economic value, productive, and of vital importance for a large number of populations of crustaceans, mollusks, and fish. The reserve contains a variety of ecosystems including marsh or land flooded by freshwater and saltwater, marine aquatic systems, bogs of brackish or salt water, reefs, mangrove forests, Pterocarpus forest, Thalassia meadows, freshwater swamp, the estuary, and the river. The reserve serves as habitat for a great variety of wildlife species, some of which have been classified as rare and endangered. In addition, evidence has been found of sites of Pre-Hispanic origin in the area of the reserve.

In terms of fauna, the area is extremely rich in birds and crustaceans. The area has great value as habitat for 65 species of birds among which is the Pelecanus occidentatis classified as a rare and endangered species. Crustaceans are of great economic importance. They have been able to identify 14 species of crabs; of which three are of high commercial value: blue land crab (Cardisoma guanhumi), swamp ghost crab (Ucides cordatus) and blue crab (Callinectes sapidus).

The reserve has 15 species of coral reefs which form to protect this natural reserve. There are crustaceans such as lobster (Panulirus argus) and prawns (Panulirus guttatus) in these reefs.

Mollusks are another species that is abundant in the area. Among the mollusks found in the area, mangrove oysters (Crassostrea rhizophorae), clams (Lucina pectinata), Queen Conch (Strombusgigas) and octopus (Octopus vulgaris) stand out. These have great nutritional and economic value and represent a source of income and food for those who catch them. Along the Río Espíritu Santo there are 60 fish species distributed in 30 families. Conserving Thalassia meadows is of great importance for West Indian manatees (Trichechus manatus).

The vast majority of the plants that grow in the area of the natural reserve are hydrophytic: plants that can tolerate the conditions of flooded lands. Species distributed in 34 plant families (predominant or most common species) have been reported. This reserve has the four species of mangrove trees: red mangrove (Rhizophora mangle); white mangrove (Laguncularia racemosa); black mangrove (Avicennia germinans); button mangrove (Conocarpus erectus) as well as herbaceous swamps.

Sea grape (Coccoloba uvifera) and Coconut palm (Cocos nucifera) resist high winds and saltpeter, as well as soil salinity. Dragonsblood trees (Pterocarpus officinalis) grow in areas that remain flooded most of the year. They are characterized by the rapid development of buttress roots and cattail (Typha domingensis).

The designation of the reserve has conservation as its main objective. Activities consistent with the conservation of natural systems in the area are: canoeing, diving, day trips, bird watching, scientific studies, swimming, water skiing, boat tours, hunting and fishing.

Author: Grupo Editorial EPRL
Published: August 27, 2014.

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