Meiofauna from Selected Biotopes and Regions

The ongoing rapid global decline in species number tells us that assessments of natural diversity (“species richness” or “biodiversity”) are necessary not only for scientific reasons, but also to substantiate conservation or sustainable regulation. Thus, studies have been initiated to file our knowledge of meiofauna diversity in numerous marine and freshwater biotopes (see international programmes and projects such as the Global Biodiversity Assessment, UNEP 1995; Convention of Biological Diversity, UNEP 2001–2005; BIOMARE, MarBEF, CenSeam; overview in Costello et al. 2006). Due to methodological problems, estimates of marine biodiversity lag behind the numerous terrestrial census studies. The book by Queirago et al. (2006) provides general information about marine biodiversity, and recently a comprehensive assessment of freshwater species has been published, edited by Balian et al. (2008; see also the earlier compilation by Segers and Martens 2005). Meiofauna were initially not included when comparing marine with terrestrial species richness. About 10 million macrobenthic marine species and between 10 and 100 million meiobenthic species are assumed to exist (Lambshead, pers. comm.).

For assesment of the biodiversity of (marine) meio benthos (both species richness = alpha diversity, and assemblage richness between habitats = beta diversity), many previously neglected regions such as the polar seas, tropical beaches and deep-sea bottoms have been studied in greater detail over the last decade. These have increased our knowledge considerably and some of these sites have turned out to be “hot spots” of meiofaunal diversity. The following chapters will characterize the ecological conditions and diversity of meiofauna in some relevant biotopes from different latitudes. The resulting questions regarding the latitudinal gradient concept (Pianka 1989) and its validity for marine meiofauna will be discussed in Box 8.3.