Nematode diversity in different microhabitats in a mangrove region

Abstract

Mangroves are highly productive environments that play important ecological and socioeconomic roles; however, they have been impacted to different degrees in most countries worldwide. The knowledge of which organisms inhabit this environment and their ecological interactions is the first step towards its conservation. The natural variability of environmental factors in mangroves provides numerous niches available to different species. Meiofauna have patchy patterns of distribution that are related to the availability of resources. Hence, meiofauna are expected to present a high diversity of different taxa occupying the different microhabitats offered by mangroves. This work aims to test the hypothesis that the assemblage structure of Nematoda varies significantly among mangrove microhabitats and to contribute knowledge on the meiofauna diversity in mangrove environments. This work was carried out in a mangrove region at Pernambuco state, Northeastern Brazil. Qualitative samples were collected in nine microhabitats which show different characteristics mainly in terms of presence of vegetation or another organism and sediment grain size. Univariate and multivariate analysis were applied to Nematoda genera abundance data. Our results demonstrate the existence of significant differences among microhabitats regarding nematode assemblage structure corroborating the hypothesis. Different Nematoda assemblages are present in at least seven microhabitats. These assemblages are composed of nematode genera with different trophic and morphological features, demonstrating a strong relationship between morphological diversity and ecological plasticity. Furthermore, this study also demonstrates the importance of the conservation of this ecosystem and its attributes.

Characteristics of meiofauna in extreme marine ecosystems: a review

“…Coull 1999;Nicholas et al 1991). Terschellingia, in particular, can account for > 50% of all nematodes (Nicholas et al 1991), but several monhysterid genera can also be highly abundant (Pinto et al 2013). Alongi (1987) suggested that high levels of sediment- Litter from mangrove leaves is rapidly colonised by meiofauna, and there is a succession of different species related to the different stages of the decomposition process (Schrijvers et al 1995;Gee and Somerfield 1997;Somerfield et al 1998;Zhou 2001), supporting the idea that meiofauna taxa play a role in litter degradation (Gee and Somerfield 1997).…”

“…The use of mangrove leaf detritus as a food source by nematodes was confirmed using isotopic markers (Demopoulos et al 2007). The pneumatophores that are colonised by macroepibenthos, such as algae, sponges or barnacles, also promote the occurrence of meiofauna (Gwyther and Fairweather 2005;Pinto et al 2013). Dye (1983) recorded a greater abundance of nematodes in mangrove-associated sediments in comparison with adjacent estuarine mudflats, illustrating the importance of vegetation in providing food and habitat (Sheridan 1997).…”

“…Meiofauna taxa are numerically dominant among benthic mangrove metazoans (Pinto et al 2013;Netto and Gallucci 2003). Nematodes withstand these extreme conditions particularly well, occasionally with high standing stocks, but with reduced diversity (Pusceddu et al 2014).…”

“…The spatial heterogeneity of mangrove sedimentary systems makes it difficult to draw general conclusions about meiofaunal diversity, since data on the number of species vary widely. Indeed, species richness tends to differ depending on the number of micro-and macrohabitats included (Somerfield et al 1998;Nagelkerken et al 2008;Pinto et al 2013). Mangroves show features that are different from other estuarine regions and may increase regional meiofauna richness.…”

Is the meiofauna a good indicator for climate change and anthropogenic impacts?

“…Meiofauna represent the most diversified group in the marine realm, encompassing 24 of the 35 animal phyla, as well as one important group of protists, the foraminifera (Giere 2009). Meiofauna are mostly found in and on soft sediments, but also on and among epilithic plants and other types of substrata (e.g., animal tubes; Pinto et al 2013). These small organisms can spend their complete life cycle without reaching sizes greater than 1 mm (permanent meiofauna), or be found in this size class for just a part of their life cycle (e.g., juveniles of macrofauna, referred to as temporary meiofauna; Hentschel and Jumars 1994).…”