Puerto Rico streams and rivers have a rich diversity that in some instances have been affected by land use changes and the construction of dams. Water quality and species diversity are an indication of the quality of streams and rivers. In this study, we describe the diversity and abundance of freshwater shrimps and crab in three rivers in the Rio Grande de Manatí Watershed in Ciales, Puerto Rico. We correlate the diversity and abundance of crustaceans to water quality and stream hydrology and habitat. We collected abundance data for the shrimp species and the freshwater crab species present in the riffles and stream or river border during 18 months. In addition, we measured water quality, hydrology factors of the streams and a conducted a rapid macroinvertebrate assessment. Correlation analysis was used to establish relationship between variables.
We found a total of 10 shrimp species in the three streams. We did not find any relationship between the water quality factors and shrimp or crab abundance. We found a relationship between the abundance of two of the shrimp species and the freshwater crab with stream width, bankfull and stream discharge. We found a relationship between stream macroinvertebrates’ biodiversity and average stream velocity. Diversity of shrimps’ species varied among the three streams. There is a difference in shrimp abundance and species between habitats (riffles and stream border). Shrimp are resilient and well adapted to changes in the water quality of streams. Functional groups are well established. Filter feeders are more abundant in the riffles than in the stream borders. Predators were more abundant in the stream borders than in the riffles. This study provides more evidence for the importance of the conservation of the watershed to maintain the integrity of the rivers and streams, essential for the principle of river continuum.