Context

The “Ouassou” (King of the Springs) is the name used in the Caribbean, particularly in Guadeloupe, to refer to several species of freshwater shrimp in the genus Macrobrachium. The term does not refer to a single species but broadly encompasses the giant freshwater shrimp found in the region.

Description

The Ouassou in this case, scientifically named Macrobrachium carcinus, belongs to the family of crustaceans often called “Ouassou” in the Caribbean, referring to freshwater shrimp of the genus Macrobrachium, also known as “giant freshwater shrimp.” It is a large freshwater crustacean, often considered one of the largest in its genus, hence its nickname “King of the Springs,” which reflects its impressive size and dominant role in freshwater ecosystems.

It is highly valued in the region for its culinary qualities, although a related species is often used in aquaculture due to challenges such as cannibalism. Beyond its culinary importance, the Ouassou also plays a crucial ecological role in the rivers and freshwater habitats where it occurs.

Macrobrachium carcinus is one of the largest freshwater shrimp, often reaching impressive sizes of 30 cm or more. Its large claws are particularly strong, allowing it to defend itself and hunt effectively.

Lifestyle

This freshwater shrimp is an important predator in its habitat, playing a crucial role in the food chain of rivers and estuaries. Often at the top of the local aquatic hierarchy—hence the nickname “King of the Springs”—it is mainly found in rivers, streams, and estuaries, moving between freshwater and brackish water. Its distribution spans the Americas, from the southern United States to South America, including the Caribbean.

1. Reproduction and Larval Development :
   
   • River reproduction: Ouassous reproduce primarily between April and November. Females carry the eggs under their abdomen until they hatch.
   • Larvae in marine environments: After hatching, the larvae are carried by river currents to the sea. Unlike adults, the larvae cannot survive in freshwater during this stage of their life.
2. Development at Sea :
   
   • Estuaries and mangroves: Ouassou larvae develop in estuaries and mangroves, where they find suitable food. These mixed habitats provide nutrient-rich environments essential for their growth.
   • Metamorphosis: After two to five months in the marine environment, larvae metamorphose into juveniles, taking on the characteristic form of adults.
3. Return to Rivers :
   
   • Upstream migration: Once juveniles, Ouassous migrate upstream from estuaries to higher freshwater areas, including mountainous regions. This migration allows them to colonize different freshwater habitats where they continue to grow.
   • Complete life cycle: Ouassous continue their life cycle in freshwater, reaching maturity and reproducing, completing the “mountain-to-sea-and-back” cycle.

The life cycle of Ouassous illustrates the importance of connections between freshwater and marine ecosystems. This migration process is essential for survival and reproduction, allowing Ouassous to benefit from the ecological advantages of each environment at different life stages.

Ecological Importance and Threats

As a predator, Macrobrachium carcinus helps regulate populations of other aquatic organisms, contributing to the balance of the ecosystems it inhabits. It also serves as a bioindicator, as its presence often reflects the water quality of its habitat.

The nickname “King of the Springs” reflects the shrimp’s strength, ecological importance, and cultural value in the Caribbean and beyond. In addition to its ecological role, Macrobrachium carcinus is highly prized for its meat, making it significant for artisanal fishing and local gastronomy in the Caribbean.

Sources

For more information, see the Guadeloupe National Park brochure (refer to sources).

panneau_rivieres.pdf (guadeloupe-parcnational.fr)

Giant river prawn – Aquatic species (fao.org)

EOL – Macrobrachium carcinus

Search Results (biodiversitylibrary.org)