UC Riverside

The meiofauna is abundant and diverse, occupying key roles in sediment food webs and nutrient cycling, and responds rapidly to environmental changes. Nematodes and copepods usually constitute the major components of the meiofauna. As well as being a large part of the meiofauna, nematodes are the most abundant and most diverse invertebrates in many sediments and soils. They occupy a wide variety of ecological roles in sediments, and their community structure provides important clues to the structure of benthic foodwebs, as well as to responses of sediment ecosystems to environmental changes such as pollution and changes in tidal range. Despite the advantages of using nematodes for biomonitoring, they are used less frequently than other groups due to some major limitations, including the so-called "taxonomic impediment". Some aspects of this impediment are illustrated via the description of new free-living nematode species. One limitation is the scarcity of expert marine nematode taxonomists and the concentration of these experts mainly in Europe. The present study is the first to investigate Californian coastal nematodes to address environmental concerns in California, specifically the restoration-in-progress of the Bolsa Chica wetland. In common practice, nematode studies usually refrain from analyzing species-level differences between sites and communities, settling instead for genus or family level identifications by way of more feasible compromise. This choice is made perforce by the challenges of working with nematodes, and meiofauna in general. Part of the present study examined whether this choice is justified in the case of free-living marine nematodes. New molecular methods present opportunities to improve biomonitoring. Whole DNA extracts from a sediment core can be subjected to massively parallel pyrosequencing of taxonomically distinctive DNA loci, producing in one procedure a comprehensive list of the great majority of interstitial invertebrates living in that sediment across most animal phyla. Determining how the detailed and relatively robust phylogenies created with these new molecular tools can be incorporated in the study of biodiversity is an important research area, as biodiversity is the main facet of biomonitoring.