The effect of macrophytes on the presence and population structure of the red swamp crayfish Procambarus clarkii (Decapoda: Cambaridae) in neotropical ecosystems

Introduction: The red swamp crayfish, Procambarus clarkii, is a crustacean species native to Mexico and the United States. It has been introduced around the world, often becoming established as an invasive exotic species. Since its introduction in 1985 in Colombia, no studies have been carried out to determine factors that influence the presence of the species in high mountain ecosystems. Objective: To evaluate the relationship over time between macrophytes and the different stages of development of P. clarkii in a tropical high Andean aquatic ecosystem. Methods: A new collection method called "macrophyte sweep" was standardized. This method ensured the collection of crayfish of all possible sizes, especially juveniles. Sampling was carried out bimonthly for seven months. The morphometry of P. clarkii was evaluated in three macrophytes: Juncus effusus, Ludwigia peruviana, and Polygonum punctatum. Results: A total of 778 individuals were collected, of which 365 were females, 344 males, and 69 sexually indeterminate. The total population density was 6.48 ind/m2. Most organisms were found on P. punctatum (71.9 %), followed by L. peruviana (17.7 %) and J. effusus (10.28 %). The largest and heaviest organisms were recorded in September in all three macrophytes, while the smallest were collected in July and May. P. clarkii exhibited a greater affinity for the macrophyte P. punctatum in its different developmental stages, possibly because it offers greater structural complexity in the submerged zone, providing shelter for juveniles and a food source for adults. Conclusions: Our results highlight that much of the colonization success of P. clarkii is due to the relationship between macrophytes and the development of different life stages in neotropical ecosystems.