**The Influential Role of the Habitat on the Diversity Patterns of Free-Living Aquatic Nematode Assemblages in the Cuban Archipelago**

**Maickel Armenteros 1,2,\*, José Andrés Pérez-García 2, Diana Marzo-Pérez <sup>2</sup> and Patricia Rodríguez-García <sup>2</sup>**


Received: 25 July 2019; Accepted: 11 September 2019; Published: 16 September 2019

**Abstract:** Free living nematodes are the most abundant and diverse metazoans in aquatic sediments. We used a framework of habitat types to reveal quantitative patterns in species richness (SR), β-diversity, and biological traits (BT). Meiofauna was quantitatively collected from 60 sites within nine habitat types and 24,736 nematodes were identified to species level. We reported a regional richness of 410 ± 12 species for the Cuban archipelago; however, caves and deep waters need to be sampled more intensively. Relationships between SR and abundance supported the dynamic equilibrium model with habitats ordered across gradients of resource availability and physical disturbance. Seagrass meadows were the most specious and freshwater/anchihaline caves the least diverse habitats. Differences in β-diversity likely were due to habitat heterogeneity and limitations for dispersal. The assemblage composition was unique in some habitats likely reflecting the effects of habitat filtering. However, coastal habitats shared many species reflecting high connectivity and dispersal capability of nematodes due to hydrodynamics. The BTs "life strategy", "trophic group", and "tail shape" reflected ecological adaptations; but "amphidial fovea" and "cuticle", likely reflected phylogenetic signatures from families/genera living in different habitats. Habitat type played an influential role in the diversity patterns of aquatic nematodes from taxonomic and functional points of view.

**Keywords:** species richness; β-diversity; biological traits; tropical; marine; freshwater; meiofauna; Caribbean
