Biodiversity patterns of free-living marine nematodes in a tropical bay: Cienfuegos, Caribbean Sea

Abstract

a b s t r a c tSpatial and temporal biodiversity patterns of free-living marine nematodes were studied in Cienfuegos Bay, a tropical semi-enclosed basin in the Caribbean Sea. Taxonomic (to species level) and functional (biological trait) approaches were applied for describing the assemblage structure and relating it to abiotic environment based on a sampling scheme in six subtidal stations and three months. Biological trait approach added relevant information to species pattern regarding relationships between diversity patterns and the abiotic environment. The most common morphotypes were deposit feeding nematodes, with colonising abilities of 2-3 (in a scale from 1 to 5), tail conical cylindrical or filiforme and body slender; and their abundance were correlated with depth, organic matter and silt/clay fraction. In spite of a high turnover of species, functional diversity of assemblages did not change notably in space and time. A result probably due to sampling of the habitat pool of species and to low heterogeneity of the studied muddy bottoms. Chemical pollution (organic enrichment and heavy metals) and hydrodynamic regime possibly drove the biodiversity patterns. Spatial distribution of assemblages support the existence of two well differentiated basins inside the bay, the northern basin more polluted than the southern one. The low hydrodynamic regime would determine a poor dispersion of nematodes resulting in high spatial variance in the assemblage structure; and also the associated hypoxic conditions and pollutants in sediments can explain the dominance of tolerant nematode species such as Daptonema oxycerca, Sabatieria pulchra, Terschellingia gourbaultae, and Terschellingia longicaudata. A comparison of spatialtemporal patterns of biodiversity between Cienfuegos Bay and other semi-enclosed bays in temperate regions suggests several similarities: nematode assemblages are strongly influenced by anthropogenic disturbance, temporal trends are weak or overridden by spatial ones, and few cosmopolitan genera/ species tolerant to pollution and hypoxic conditions are dominant.

Taxonomic resolution and Biological Traits Analysis (BTA) approaches in estuarine free-living nematodes

“…Similar outcomes were observed by Schratzberger et al (2007) for nematode assemblages in the North Sea and Armenteros et al (2009) in the Caribbean Sea, where the inclusion of trait-based analyses provided additional information of community distribution patterns regarding different environmental factors. In the present study although the information obtained by the taxonomic approach was not superimposed on that obtained with the functional ones, the distribution patterns of the communities related to similar sets of environmental parameters.…”

“…The use of biological traits has been strongly encouraged in studies aiming at analysing diversity patterns (Armenteros et al, 2009) and assessing ecosystem functioning (Bremner et al, 2003). In this context, since trait-based approaches are known for their high robustness with decreased taxonomic resolution (Menezes et al, 2010), problems associated with misidentification can be less critical since nematode species with high morphological similarity will most probably share the same trait category.…”

The nematode assemblage of a coastal lagoon (Lake Varano, southern Italy): ecology and biodiversity patterns

“…Although the MI may generally give good results in ecological assessments , Armenteros et al (2009) reported unclear results in Cienfuegos Bay (Caribbean Sea), especially for the interaction of anthropogenic and natural factors. A clear relationship between anthropogenic activity (PLI) and the MI was not found in Lake Varano.…”

“…It is also well known as tolerant to a variety of natural and anthropogenic stressors (e.g. Armenteros et al 2009, Gollner et al 2010, Guilini et al 2012. The physiological and behavioural adaptations of T. longicaudata to poorly oxygenated environments include a low respiratory rate and slow movement (Warwick andGee 1984, Guerrini et al 1998).…”

“…It dwells deep in the sediment, and is often found in high densities near the redox potential discontinuity layer (Wetzel et al 2002, Steyaert et al 2003, 2005. Data from a heavily polluted, tropical semi-closed bay (Havana Bay) revealed an enhancement of S. pulchra over T. longicaudata, probably due to the increase in grain size (Armenteros et al 2009). This could explain the lack of a close correlation between S. pulchra and silt.…”