Katarzyna Grzelak

Meiofaunal distribution in Hornsund fjord, Spitsbergen

The meiofaunal community structure at 32 stations in Hornsund fjord (77°N) was investigated, and results were compared with data from another Spitsbergen fjord, Kongsfjorden (79°N). Steep environmental gradients of sedimentation, organic matter content, and salinity from the inner to the outer basin of the fjord are present due to intensive glacial discharges of meltwater and ice. As the natural environmental disturbances were described for macrofauna benthic communities before, we aimed to check whether the same pattern occurs among meiofauna. A total of 12 higher meiofaunal taxa were recorded, with nematodes predominating at all stations. Non-parametric multivariate analyses demonstrated clear differences in meiofaunal abundance and composition between stations in the glacial bay and in the outer part of the fjord. Meiofaunal abundance increased with increasing distance from the source of disturbance, which in our study is tidal glaciers. Therefore, the current study demonstrates that the spatial structure of meiofauna is affected by the natural environmental disturbance, and analysis of meiofaunal assemblages can be used to assess the effect of such disturbances.

Benthic assemblages associated with rocks in a brackish environment of the southern Baltic Sea

Sandy bottoms, with local patches of rocks, dominate the southern Baltic Sea coast. These rock patches create three-dimensional habitats with additional niches that can support diverse assemblages of organisms. In this study we investigated macrofaunal assemblages associated with the boulder field in the brackish Gulf of Gdansk. Of the 30 recorded taxa three animal species (Mytilus trossulus, Balanus improvisus and Electra crustulenta) together with five species of algae were directly attached to rocks. These engineering organisms provided habitats for a further 22 taxa. Among the fauna directly associated with rocks, barnacles ( 7 6%) were the most abundant while among indirectly associated biota, oligochaetes were the dominant group ( 45 %). Rock size and algal biomass explained most variance in macrofaunal structure of the assemblages investigated. There were statistical differences in assemblage structure between two separate localities within the rocky patch, despite environmental homogeneity (salinity, water temperature and structure of sea bottom). These differences in assemblage structure were mostly due to differences in dominance of particular species rather than in species composition. Our results show that rocky patches in an otherwise soft sediment habitat provide additional living space for macrofauna leading to an increase in local biodiversity and organismal abundance.

New species of Echinoderes (Kinorhyncha: Cyclorhagida) from Spitsbergen, with additional information about known Arctic species

ABSTRACT The kinorhynch fauna in two Arctic fjords at Spitsbergen was explored and eight species of Echinoderes were recorded, of which three are new to science and described herein. Echinoderes daenerysae sp. nov. is recognized by middorsal spines on segments 6 and 8 only, lateroventral spines on segments 6–9, laterodorsal and ventrolateral tubes on segment 2, lateroventral tubes on segment 5, lateral accessory tubes on segment 8, laterodorsal tubes on segment 9 and small laterodorsal tubes on segment 10. Echinoderes rhaegali sp. nov. has middorsal spines on segments 4, 6 and 8, lateroventral spines on segments 6–9, sublateral and ventrolateral tubes on segment 2, lateroventral tubes on segment 5, lateral accessory tubes on segment 8 and laterodorsal tubes on segment 10 in males. Echinoderes drogoni sp. nov. has middorsal spines on segments 4–8, lateroventral spines on segments 6–9, lateral accessory tubes on segment 5, glandular cell outlets type 2 in subdorsal, laterodorsal, sublateral and ventromedial positions on segments 2, in midlateral positions on segment 5, in sublateral positions on segment 8 and in subdorsal positions on segment 10; segment 11 has divided tergal plates. Moreover, types of other Arctic Echinoderes, including E. angustus, E. aquilonius, E. eximus, E. peterseni, E. svetlanae and E. tubilak, were re-examined and new information on glandular cell outlets type 2 is provided. Our results suggest that Arctic Echinoderes species have a circum-Artic distribution. Morphological analysis indicates that the occurrence of tubes may show intraspecific variation. http://zoobank.org/urn:lsid:zoobank.org:pub:CBE29FE8-9233-4E3C-9757-FF9576B06C74

Ecological Status of Sandy Beaches After Tsunami Events: Insights from Meiofauna Investigations After the 2011 Tohoku-oki Tsunami, Sendai Bay, Japan

Tsunami may strongly impact beach ecosystems. To assess its magnitude five beaches along the Sendai Bay, Japan, were studied 2 months after the 11th March 2011 Tohoku-oki tsunami with focus on their recovery and meiofauna assemblages within few weeks after the event. The beaches recovered and new meiofauna assemblages established, which were strongly correlated to sediment grain size. The new data and review of previous works suggest that for beach ecosystems tsunami plays a role of ecosystem disturbance, not a catastrophe.

Checklist of Gastrotricha of the Polish Baltic Sea with the first reports of Heterolepidoderma joermungandri Kånneby, 2011, and Turbanella hyalina Schultze, 1853

Gastrotricha is a cosmopolitan phylum of aquatic and semi-terrestrial invertebrates comprising more than 800 described species. Up to now, only five taxonomic and faunistic papers have been published on the gastrotrichs of the Polish Baltic Sea and 27 taxa have been found (including three freshwater, which were found in estuaries). This article presents a complete list of brackish and estuarine Gastrotricha from the Polish Baltic Sea accompanied by localities and the first observations of gastrotrich species inhabiting the underwater macrophytes. Although the group has been studied for more than 150 years, the gastrotrich community of marine macrophytes has not been studied in any great detail. Here we provide data on gastrotrich communities living on macrophytes and also in sandy sediments. In total, nine species were found (seven from sandy sediments, two species from macrophytes). Seven of the species belong to Chaetonotida: Halichaetonotus balticus Kisielewski, 1975, H. lamellatus Kisielewski, 1975, H. schromi Kisielewski, 1975, Heterolepidoderma joermungandri Kånneby, 2011, Lepidodermella squamata (Dujardin, 1841), Xenotrichula intermedia Remane, 1934, and X. velox Remane, 1927(c). Two of species belong to Macrodasyida: Turbanella cornuta Remane, 1925, and T. hyalina Schultze, 1853. H. joermungandri and T. hyalina are new for Polish fauna. Both species correspond with the original descriptions but differ by some morphometric characters. Taxonomic, morphometric, and biogeographic remarks are provided for the new records together with differential interference contrast (DIC) microphotographs.

Diversity and distribution of Arctic Echinoderes species (Kinorhyncha: Cyclorhagida), with the description of one new species and a redescription of E. arlis Higgins, 1966

The kinorhynch fauna from Svalbard and the Arctic Ocean north of Svalbard was explored, and a total of nine species of Echinoderes was identified. Two species were new to science, and one, Echinoderes balerioni sp. nov., is described. Echinoderes balerioni sp. nov. is characterized by the presence of short middorsal spines on segments 4, 6, and 8, and in lateroventral positions on segments 6 to 9. Tubes are present in laterodorsal, sublateral, and ventrolateral positions on segment 2, lateroventral positions on segment 5, and lateral accessory positions on segment 8, and tergal extensions conspicuously long and spiniform. The collected material also offered the first chance to examine specimens of Echinoderes arlis with scanning electron microscopy, which prompted a redescription of the species. The recorded species are compared with all other known records of Echinoderes in the Arctic region, and the summarized data suggests that at least some species show a circumpolar distribution.

Ecostructuring of marine nematode communities by submarine groundwater discharge

Inputs of submarine groundwater discharge (SGD) to the coastal ocean may alter local and regional-scale biology. Here, we report on nematode assemblages along the north shore of Long Island, NY. We test if nematode communities differed between sites impacted by mixed fresh-saline SGD and where SGD is exclusively saline. Diversity of nematodes was low at sites impacted by fresh SGD and communities were dominated by a few opportunistic genera. Moreover, a set of typical freshwater nematode genera restricted to impacted sites was observed. Their presence in the marine coastal zone is exceptional and underlines the structuring role that fresh SGD plays in the local ecosystem. Saline SGD structured nematode assemblages differently compared to sites impacted by fresh SGD. The number of nematode genera was markedly higher at saline SGD sites, with a different community structure. This study highlights the importance to which inputs of fresh SGD may have on local ecosystem diversity in marine coastal environments.

First observation of the marine tardigrades Batillipes mirus and Batillipes noerrevangi (Arthrotardigrada, Batillipedidae) from a strongly brackish part of the Polish Baltic Sea coast

Abstract The tardigrade fauna of Poland is one of the better known in Europe. However, almost all studies have been carried out on the limno-terrestrial species, while marine Tardigrada have been neglected. To the best of our knowledge only one report on marine Tardigrada for Polish waters has been published up to now. In the present study the first records of two marine arthrotardigrade species, Batillipes mirus and Batillipes noerrevangi, from Puck Bay (Baltic Sea) are reported. The lowest salinity value in the study area was 3–4 PSU, and B. noerrevangi should be considered the most brackish water-tolerant arthrotardigrade. Samples were collected from the vegetated seabed (seagrass and macrophytes) and the bare sandy bottom in different seasons. A single specimen of B. mirus was found only during the autumn campaign. Specimens (adults and larval stages) of B. noerrevangi were found in all samples during spring, summer and autumn campaigns. Additionally, morphometric data with detailed microphotographs of B. noerrevangi (PCM, DIC) and B. mirus (PCM) as well as a discussion of the new records are presented. The validity of the occurrence of B. dicrocercus in Poland, which was determined based on a single larva from the Międzyzdroje area by Hummon, is also discussed. The larva from Międzyzdroje should be regarded as an undetermined species; thus, the marine tardigrade fauna from Poland consists of only the two newly recorded species.

Echinoderes pterus sp. n. showing a geographically and bathymetrically wide distribution pattern on seamounts and on the deep-sea floor in the Arctic Ocean, Atlantic Ocean, and the Mediterranean Sea (Kinorhyncha, Cyclorhagida)

Abstract Kinorhynchs rarely show a wide distribution pattern, due to their putatively low dispersal capabilities and/or limited sampling efforts. In this study, a new kinorhynch species is described, Echinoderes pterus sp. n., which shows a geographically and bathymetrically wide distribution, occurring on the Karasik Seamount and off the Svalbard Islands (Arctic Ocean), on the Sedlo Seamount (northeast Atlantic Ocean), and on the deep-sea floor off Crete and on the Anaximenes Seamount (Mediterranean Sea), at a depth range of 675–4,403 m. The new species is characterized by a combination of middorsal acicular spines on segments 4–8, laterodorsal tubes on segment 10, lateroventral tubes on segment 5, lateroventral acicular spines on segments 6–9, tufts of long hairs rising from slits in a laterodorsal position on segment 9, truncated tergal extensions on segment 11, and the absence of any type-2 gland cell outlet. The specimens belonging to the populations from the Arctic Ocean, the Sedlo Seamount, and the Mediterranean Sea show morphological variation in the thickness and length of the spines as well as in the presence/absence of ventromedial sensory spots on segment 7. The different populations are regarded as belonging to a single species because of their overlapping variable characters.

New mud dragons from Svalbard: three new species of Cristaphyes and the first Arctic species of Pycnophyes (Kinorhyncha: Allomalorhagida: Pycnophyidae)

Background Kinorhynchs are marine, microscopic invertebrates inhabiting the seafloors. Their segmented trunk equipped with spines and processes has inspired scientists to give them the common name “mud dragons.” Even though kinorhynchs have been known since the 19th century, less than 300 species are known to science, and it is still considered a largely understudied animal group—in particular in the Arctic, from which only 23 species are known so far. Methods Samples were collected at eight stations around Svalbard and in the fjords of Spitsbergen. Meiofauna was extracted from the sediment cores with LUDOX centrifugation method, and kinorhynchs were picked up and mounted for light- and scanning electron microscopy. Results Four new species of the kinorhynch family Pycnophyidae are described from Svalbard: Cristaphyes dordaidelosensis sp. nov., C. glaurung sp. nov., C. scatha sp. nov., and Pycnophyes ancalagon sp. nov. The new species are generally recognized by their distribution of setae along the trunk segments. Discussion After the discovery of the new species, Pycnophyidae becomes with 14 species the most diverse kinorhynch genus in the Arctic, closely followed by Echinoderidae with 13 species. So far, these are the only kinorhynch families with an Arctic distribution.