title: Cryptic diversity and ecosystem functioning: a complex tale of differential effects on decomposition.
abstract: Marine ecosystems are experiencing accelerating population and species loss. Some ecosystem functions are decreasing and there is growing interest in the link between biodiversity and ecosystem functioning. The role of cryptic (morphologically identical but genetically distinct) species in this biodiversity-ecosystem functioning link is unclear and has not yet been formally tested. We tested if there is a differential effect of four cryptic species of the bacterivorous nematode Litoditis marina on the decomposition process of macroalgae. Bacterivorous nematodes can stimulate or slow down bacterial activity and modify the bacterial assemblage composition. Moreover, we tested if interspecific interactions among the four cryptic species influence the decomposition process. A laboratory experiment with both mono- and multispecific nematode cultures was conducted, and loss of organic matter and the activity of two key extracellular enzymes for the degradation of phytodetritus were assessed. L. marina mainly influenced qualitative aspects of the decomposition process rather than its overall rate: an effect of the nematodes on the enzymatic activities became manifest, although no clear nematode effect on bulk organic matter weight loss was found. We also demonstrated that species-specific effects on the decomposition process existed. Combining the four cryptic species resulted in high competition, with one dominant species, but without complete exclusion of other species. These interspecific interactions translated into different effects on the decomposition process. The species-specific differences indicated that each cryptic species may play an important and distinct role in ecosystem functioning. Functional differences may result in coexistence among very similar species.
authors.affiliation: Marine Biology Unit, Department of Biology, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium. nele.demeester@ugent.be.|Center for Molecular Phylogeny and Evolution, Ghent University, Ghent, Belgium. nele.demeester@ugent.be.
authors.forename: N
authors.initials: N
authors.lastname: De Meester
authors.affiliation: Marine Biology Unit, Department of Biology, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium.|Department of Biological Oceanography, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico.|SWEEP and More Company, Schillstrasse 16, 24118, Kiel, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Gingold
authors.affiliation: Marine Biology Unit, Department of Biology, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium.|Center for Molecular Phylogeny and Evolution, Ghent University, Ghent, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Rigaux
authors.affiliation: Marine Biology Unit, Department of Biology, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium.|OD Taxonomy and Phylogeny, Royal Belgian Institute of Natural Sciences, Vautierstraat 29, 1000, Brussels, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Derycke
authors.affiliation: Marine Biology Unit, Department of Biology, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Moens
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D009348:Nematoda; D013045:Species Specificity
keywords: Biodiversity–ecosystem functioning link; Competition; Functional differences; Litoditis marina; Marine nematodes