Multi-marker DNA metabarcoding reflects tardigrade diversity in different habitats

Like meiofauna in general, tardigrades are often neglected in ecological and environmental surveys. Tardigrades occur in all parts of the world, from deep marine sediments to alpine environments, and are present in most ecosystems. They are therefore potentially good candidates for biomonitoring programs. However, sampling of these minute animals is both tedious and time-consuming, impeding their inclusion in large-scale ecological surveys. In this study we argue that using a multi-marker metabarcoding approach on environmental DNA partly can overcome this barrier. Samples of moss, lichens and leaf litter were investigated both by morphology-based methods and DNA metabarcoding, and the results were compared in terms of tardigrade diversity and community composition of the sampled microhabitats. DNA metabarcoding using three markers detected more species of tardigrades than identification by morphology in most samples. Also, metabarcoding detected the same community differences and microhabitat distribution patterns as morphology-based methods. In general, metabarcoding of litter samples was unreliable, with only one out of three markers consistently amplifying and detecting tardigrades. The low availability of tardigrade reference sequences in public databases restricts the taxonomic resolution in eDNA surveys, but this impediment is partly circumvented by utilizing multiple markers

Richness of Thalloid Liverworts in Bilaspur, Achanakmar-Amarkantak Biosphere Reserve and Lafa hills, Chhattisgarh (India)

A survey of bryophyte diversity in Bilaspur District (Chhattisgarh) and nearby areas has brought to light an unexpectedly rich bryoflora. Liverworts have a great diversity which includes both leafy and thalloid forms. Presence of 24 species of thalloid liverworts was recorded collectively from protected area Achanakmar-Amarkantak Biosphere reserve (AABR) as well as other regions of Bilaspur district and Lafa Hills, Korba. The main objective of this study is to evaluate the influence of elevation on the diversity of bryophytes in regional scale. For the study each location was mapped zone wise on 21 micro plots ranging between altitudes 230 m to 1011 m. Using presence or absence of species, bryophyte species richness was compared at each altitude. These zones exhibit high species richness at mid–high elevation (around 525-1000 m) with an average 4-6 species of distribution rate. It is observed 83% of liverwort population as terrestrial, 10% as epiphytic, 7% grows in aquatic habitats and below 5% recorded as ubiquitous at various altitude ranges. Species composition shows variability along the elevation and microhabitat distribution which shows homogeneity of liverwort population. This study reveals the current status of liverworts in Bilaspur region.

The effects of brown trout (Salmo trutta morpha fario) on habitat selection by larval Fire Salamanders (Salamandra salamandra): a predator-avoidance strategy

Predatory fish can have a major impact on aquatic amphibian assemblages. Knowledge regarding the influence of habitat heterogeneity on predator–prey dynamics is extensive, but not much is published on how the habitat structure influences the co-occurrence of brown trout (Salmo trutta Linnaeus, 1758 morpha fario) and Fire Salamander (Salamandra salamandra (Linnaeus, 1758)). I examined the microhabitat distribution of larval salamanders relative to the presence of brown trout and stream morphology, hypothesizing that larval salamanders will increase their habitat use in the presence of trout to avoid predation. Fish and salamanders were sampled with an electroshocker in 62 instream habitat patches. In the stream zone populated by brown trout, larval salamanders avoided high-quality habitats such as pools, whereas they strongly preferred them in the fishless zone (their densities were ∼10 times lower in pools than in riffles). Brown trout mainly occupied deeper pools. The co-occurrence of larval Fire Salamanders with trout suggests the presence of an effective predator-avoidance strategy. The predator-avoidance response and habitat-use pattern decreased interspecific overlap, leading to the use of different instream spaces. Heterogeneous habitats enable habitat partitioning between larval salamanders and brown trout, which means that the natural characteristics of streams promote coexistence between fish and amphibians.

Microhabitat distribution and behaviour of Branchiobdellidan Holtodrilus truncatus found on the freshwater shrimp Neocaridina spp. from the Sugo River, Japan

A study was performed on the microhabitat distribution and some aspects of behaviour of the ectosymbiotic branchiobdellidan Holtodrilus truncatus (Annelida, Clitellata) found on the freshwater shrimp that inhabit the Sugo River, Hyogo Prefecture, western Japan. Observations on shrimp that were collected from the Sugo River (2003 to 2011) confirmed that the host shrimp is Neocaridina spp. (Atyidae). The attachment location on the host shrimp was predominately between the 1st pleopod and the 5th pereopod (55.3%). The reproductive method of H. truncatus is hemaphroditism. The cocoon was found only inside the carapace of the host shrimp. The cocoon was transparent and contained a maximum of 14 juvenile worms (developing embryos). When hatching approached, H. truncatus’s worms became elongated and slender, and only one worm hatched out at a time. When Holtodrilus truncatus was removed from its host and was maintained in river water without any food, it survived for a maximum of 46 days. In a host exchange experiment, where we provided several other freshwater shrimp species, Palaemonidae fed on H. truncatus. Moreover, Palaemon paucidens and Macrobrachium nipponense from Lake Biwa also preyed upon H. truncatus. The possible symbiotic relationship between H. truncatus and Neocaridina spp. (family Atyidae) is further discussed.