Spatial variation of meiofaunal tardigrades in a small tropical estuary (~6°S; Brazil)

Abstract

Spatial variations and organism–sediment relationship are paramount subjects of soft-bottom ecology. However, these issues have been unexplored for most minor meiofaunal taxa such as tardigrades. In the present study, we explore this subject on a small tropical (~6°S) estuary. Total meiofaunal abundance ranged from 4 to 1036 individuals per 10cm2, averaging (mean±s.d.) 324.8±245.9 individuals per 10cm2. Nematodes dominated in both seasons, representing >70% of total abundance. Tardigrades were the second-most abundant taxon, representing 15% of the total and up to 71%. Tardigrades were represented by two species, Batillipes dandarae and B. pennaki, the latter dominating in the rainy season, and both with similar abundances in the dry season. Abundance of total meiofauna and both tardigrade species differed significantly (ANOVA; P<0.05) among stations and in the interaction between stations and seasons, but only B. dandarae varied seasonally, with higher values occurring in the dry season. The spatial variations observed were mostly related to differences in the sediment granulometry. Environmental explanatory variables explained 72.6% of the variance of dominant meiofaunal taxa in the Redundancy Analysis. Nematodes and ostracods were mostly associated with fine and very fine sands, both tardigrades with medium sand and oligochaetes with larger size-fractions of the sediment and organic matter. The data gathered here suggest that granulometry was the most important environmental factor in the meiofaunal spatial structure in tropical estuaries and both tardigrade species were closely associated with medium sand.

The toughest animals of the Earth versus global warming: Effects of long‐term experimental warming on tardigrade community structure of a temperate deciduous forest

“…Tardigrade responses to small-scale habitat heterogeneity (patchiness) could explain the high variability among pseudoreplicates as shown to be the predominant source of variance for all six examined indexes (Table 2). Leetham et al (1982) and Hohberg (2006) also found a high intrasite variance in the number of tardigrades in soil habitats, and a similar level of patchiness has been shown for other substrates as well (Meyer, 2006;Sohlenius et al, 2004;Tilbert et al, 2019). In our experimental setup, soil moisture was not correlated with air temperature and was instead correlated with air relative humidity (Burt et al, 2014).…”

“…Leetham et al. (1982) and Hohberg (2006) also found a high intrasite variance in the number of tardigrades in soil habitats, and a similar level of patchiness has been shown for other substrates as well (Meyer, 2006; Sohlenius et al., 2004; Tilbert et al., 2019). In our experimental setup, soil moisture was not correlated with air temperature and was instead correlated with air relative humidity (Burt et al., 2014).…”

Benthic meiofauna with emphasis on nematode assemblage response to environmental variation in the intertidal zone of the Danshuei River estuary, northwest Taiwan

“…These are factors which all reduce the abundance of interstitial fauna (Monterey Bay at National Marine Sanctuary, 2019). Granulometry was suggested as the most important environmental factor for structuring meiofauna in tropical estuaries (Tilbert, de Castro, Tavares, & Júnior, 2019). Our results also showed that sediment particle size was an important environmental variable affecting the composition and distribution of nematode assemblages.…”

Foraminiferal assemblage structure from Brazilian tropical urbanized beaches (~7°S)

“…The taphonomic cluster followed a geographic pattern, since Lucena and Miramar were close to each other in the north and reflects their deposition and abrasion dynamics. For the taxonomic cluster the characteristic of the type of the sediment of each beach was preponderant; while medium and coarse gains predominated in most sampled beaches, at Miramar fine and very fine sand predominated (~80%), what usually is associated to higher organic content (Moore 1958, Ferreira 1977, 1978, Tilbert et al 2019. In addition, Miramar seems to be becoming a lagoon, with very low hydrodynamic energy and high salinity.…”