Ecological factors determining Tardigrada distribution in Costa Rica

Abstract

Over 700 moss, lichen and hepatic samples were collected from territory of Costa Rica. Tardigrades were present in nearly half of the samples. Overall, more than 7000 tardigrades were found. All specimens were identified as 64 species belonging to 18 genera. The number of species per positive sample varied between 1 and 10, but on average it did not exceed three. The most important factor influencing distribution of Tardigrada in Costa Rica was altitude. Tardigrades most often inhabited mosses, lichens and hepatics collected from 2000 to 2400 m asl and above 3200 m asl (more than 70% positive samples). The highest Tardigrada species diversity was found between 1400 and 2000 m asl (35 species, 55%), and the lowest between 2400 and 2800 m asl (18 species, 28%). The second strongest factor that influenced tardigrade distribution was the type of environment. A significantly higher proportion of positive samples were found in urban and agricultural areas (about 60%) than in natural habitats (only about 30%). The highest frequency of positive samples was found in humid habitats. Surprisingly, among all analysed factors, the substrate and plant type had the weakest influence on tardigrade distribution.

Distribution and diversity of Tardigrada along altitudinal gradients in the Hornsund, Spitsbergen (Arctic)

“…The growth form of a moss or lichen, and its effect on micro-environmental conditions (i.e., moisture), is probably more significant than the substrate species (e.g., Jö nsson 2003Jö nsson , 2007Meyer 2006a;Guil, Hortal et al 2009;). Still, the overall meso-climatic regimes of the environment in which the cryptogam grows (such as rainfall, humidity, exposure, insulation and temperature) seem to be chiefly responsible for the development and maintenance of tardigrade populations (Schuster & Greven 2007;Guil, Hortal et al 2009;Kaczmarek, Gołdyn, Wełnicz et al 2011). It therefore seems reasonable to conclude that neither the type of vegetation nor differences in moss and lichen species significantly influenced tardigrade composition along the altitudinal gradients investigated in the present study.…”

“…A significant relationship between the structure of tardigrade communities and elevation has been documented by a number of studies (e.g., RodriguezRoda 1951;Nelson 1975;Dastych 1980Dastych , 1985Dastych , 1987Dastych , 1988Beasley 1988;Collins & Bateman 2001;Guil, Hortal et al 2009;Kaczmarek, Gołdyn, Wełnicz et al 2011). However, it is not clear which variables covarying with elevation (e.g., climate, vegetation or others) are responsible for shaping tardigrade diversity, distribution and abundance.…”

“…Although it has been suggested that substrate species may influence tardigrade community composition (e.g., Dastych 1980Dastych , 1985Dastych , 1988Hofmann 1987), and the issue has been widely debated in literature, so far there is no convincing evidence for any specific associations between moss species and tardigrade distribution and abundance (e.g., Nelson 1975;Ramazzotti & Maucci 1983;Kathman & Cross 1991;Meyer 2006a). It has also been found that the same moss species growing in different environmental conditions contained different tardigrade communities (Jö nsson 2003;Guil, Hortal et al 2009;Kaczmarek, Gołdyn, Wełnicz et al 2011). Taking into account that a given cryptogam species may appear in a range of environmental conditions, it seems unlikely that the plant species itself determines the occurrence and diversity of tardigrades.…”

The influence of a seabird colony on abundance and species composition of water bears (Tardigrada) in Hornsund (Spitsbergen, Arctic)

“…Bartels and Nelson (2006) observed that tardigrade species' richness was always lower in lichens than in mosses in Great Smoky Mountains National Park (North Carolina, Tennessee, USA). Additionally, a study conducted in Costa Rican rainforests revealed that plant type had the weakest influence on tardigrade distribution (Kaczmarek et al 2011b). …”

New records of tardigrades from Colombia (Guatavita, Cundinamarca Department)

“…120, and Romania ca. 140 (see Degma, 2006;Kaczmarek et al 2010aKaczmarek et al , 2010bKaczmarek et al, 2012;Vargha, 2012;Zawierucha et al, 2013;Ciobanu et al, 2014;Coulson et al, 2014;Lisi et al, 2014). Knowledge on the tardigrade fauna of Colombia also looks very poor in comparison with knowledge of tardigrade fauna of Central and South America (100 species known from Central America, 220 from South America, and 251 from the entire Neotropical region) (Meyer, 2013;Kaczmarek et al, 2014b).…”