Eike Rachor

Macrofauna associated with macroalgae in the Kongsfjord (Spitsbergen)

Abstract. Macrofauna associated with six abundant macroalgal species was investigated in Kongsfjord, Spitsbergen, in order to qualitatively and quantitatively describe macroalgal epifauna composition. A total of 104 invertebrate species were identified, with bryozoans and amphipods representing the most abundant taxa. Analysis of similarity of epifaunal composition showed differences between algal species, and four groups could be distinguished: a Laminaria-Alaria group, a Ptilota-Phycodrys group, Desmarestia aculeata and Acrosiphonia aff. flagellata. Abiotic factors such as temperature and salinity were found to play a minor role in structuring epifaunal communities, while wave action and ice abrasion at least partially determine the epifauna on plants growing in the upper sublittoral. Major factors influencing composition of associated epifauna are the overall growth form and the three-dimensional thallus structure of macroalgae. None of the epifaunal species showed high host specificity. Patterns of dominating animal taxa and distribution among algal groups in Kongsfjord are similar compared to other biogeographic regions, although epifauna associated with Arctic macroalgae seems to be less rich in species.

Megabenthic communities in the waters around Svalbard

Abstract Composition and distribution of megabenthic communities around Svalbard were investigated in June/July 1991 with 20 Agassiz trawl and 5 bottom trawl hauls in depths between 100 and 2100 m. About 370 species, ranging from sponges to fish, were identified in the catches. Species numbers per station ranged from 21 to 86. Brittle stars, such as Ophiacantha bidentata, Ophiura sarsi and Ophiocten sericeum, were most important in terms of constancy and relative abundance in the catches. Other prominent faunal elements were eunephthyid alcyonarians, bivalves, shrimps, sea stars and fish (Gadidae, Zoarcidae, Cottidae). Multivariate analyses of the species and environmental data sets showed that the spatial distribution of the megabenthos was characterized by a pronounced depth zonation: abyssal, bathyal, off-shore shelf and fjordic communities were discriminated. However, a gradient in sediment properties, especially the organic carbon content, seemed to superimpose on the bathymetric pattern. Both main factors are interpreted as proxies of the average food availability, which is, hence, suggested to have the strongest influence in structuring megabenthic communities off Svalbard.

Data integration for European marine biodiversity research: creating a database on benthos and plankton to study large-scale patterns and long-term changes.

The general aim of setting up a central database on benthos and plankton was to integrate long-, medium- and short-term datasets on marine biodiversity. Such a database makes it possible to analyse species assemblages and their changes on spatial and temporal scales across Europe. Data collation lasted from early 2007 until August 2008, during which 67 datasets were collected covering three divergent habitats (rocky shores, soft bottoms and the pelagic environment). The database contains a total of 4,525 distinct taxa, 17,117 unique sampling locations and over 45,500 collected samples, representing almost 542,000 distribution records. The database geographically covers the North Sea (221,452 distribution records), the North-East Atlantic (98,796 distribution records) and furthermore the Baltic Sea, the Arctic and the Mediterranean. Data from 1858 to 2008 are presented in the database, with the longest time-series from the Baltic Sea soft bottom benthos. Each delivered dataset was subjected to certain quality control procedures, especially on the level of taxonomy. The standardisation procedure enables pan-European analyses without the hazard of taxonomic artefacts resulting from different determination skills. A case study on rocky shore and pelagic data in different geographical regions shows a general overestimation of biodiversity when making use of data before quality control compared to the same estimations after quality control. These results prove that the contribution of a misspelled name or the use of an obsolete synonym is comparable to the introduction of a rare species, having adverse effects on further diversity calculations. The quality checked data source is now ready to test geographical and temporal hypotheses on a large scale.

A seafloor crater in the German Bight and its effects on the benthos

Abstract In 1963 a deep crater was formed about 65 m below sea level in the western part of the German Bight, due to a gas eruption caused by drilling carried out from the platform ’Mr. Louie’. The study area is situated in a sandy to muddy bottom area inhabited by an Amphiura filiformis association (sensu Salzwedel et al. 1985). The crater, sometimes called ’Figge-Maar’, functions as a sediment trap, concentrating particles and organisms from the water column, thus leading to extreme sedimentation rates of about 50 cm, on average, per year. Crater stations, compared with stations situated in the vicinity, show enrichments of juveniles. Echinoderms, especially the subsurface-dwelling heart urchin Echinocardium cordatum and ophiuroids are responsive to enrichment. Other species that are typical of the Amphiura filiformis association are shown to be unable to cope with the special conditions in the crater.

Meroplankton distribution in the central Barents Sea in relation to local oceanographic patterns

Abstract. Abundance and spatio-temporal distribution of meroplankton (larvae of invertebrate benthos) in the central Barents Sea and their dependence on abiotic factors were investigated. Samples were taken in different depth intervals on a south-north transect in the marginal ice zone in May 1997. At several locations sampling was repeated in June 1997. In May, total meroplankton abundances varied between 0.1 ind. m–3 and 32.0 ind. m–3, but mainly fluctuated around 10–15 ind. m–3. They were strongly affected by the mass occurrence of single species. At the northern, heavily ice-covered stations numbers decreased significantly. Larvae of 27 types were found. Polychaetes represented the most diverse group (13 species), followed by echinoderms (8 species). Larvae of only one bivalve species were found (Mya truncata), but with very high abundances (86 ind. m–3). Other taxa were represented only by single specimens. In June, total abundances were similar. The same species were present but the distribution patterns were less distinct, diversity values were higher and most larvae were further developed than in May. Distribution patterns of the larvae were to a large extent determined by physical processes in the area of the Polar Front, which acted as a distinct barrier in surface waters. In May, four meroplankton assemblages were distinguished, each associated with a different water mass. Most of the larvae have also been found in other investigated Arctic areas and belong to species with an Atlantic-Boreal-Arctic or Boreal-Arctic distribution. The relatively high numbers of larval types found in this study indicate that indirect development with pelagic larval stages plays a role in benthic recruitment in this sub-Arctic region. The relevance of these observations for the so-called Thorson rule is discussed.

Macrobenthos Distribution in the Laptev Sea in Relation to Hydrology

As a results of six joint expeditions to the Laptev Sea in 1993, 1994 and 1995, 150 invertebrate species were added to the list of species known from this high-Arctic region, comprising now 1235 species in total. Most of these species (987) are macrozoobenthic. The geographic distribution of macrobenthic species numbers and biomass exhibited a pronounced increase to the north up to 77°N. In terms of biogeographic composition, Boreal-Arctic species accounted for most of the species, primarily widespread Boreal-Arctic species in the southern and central Laptev Sea at depths from 10 to 75 m and primarily Atlantic Boreal-Arctic species in the northern Laptev Sea at depths of 90 to 1100 m. Only in depths of more than 2000 m, as well as in estuarine and brackish coastal waters, Arctic forms had significant species shares. On sandy and silty bottoms, nine major communities and two trophic zones were distinguished. The distribution of species numbers, biomass and faunal composition is discussed in relation to water depth, seabed sedimentology and near-bottom water salinities. The latter are supposed to be the major environmental factor regulating the distribution and structure of macrobenthic communities. An ecological-biogeographical zonation scheme is proposed, combining the current information about the distribution of macrobenthic communities and brackish water masses.

The association between the caprellid Pariambus typicus Krøyer (Crustacea, Amphipoda) and ophiuroids

Caprellid amphipods are small marine crustaceans which usually live as epibionts on a variety of substrates. Apart from mostly sessile organisms such as algae, hydroids and bryozoans, they also frequently use vagile fauna as substrates. Pariambus typicus (Kroyer, 1844) is a common associate of subtidal asteroids and echinoids in European seas, but has also been found free-living on the sea floor. In the German Bight, P. typicus has also been discovered regularly on ophiuroids (Ophiura albida Forbes and Ophiura ophiura (L.)), which had not been described before. Several aspects of the biology of both partners were investigated with major focus on their distribution and relation to different substrates, behavioural and morphological adaptations to their habitat and their modes of nutrition. Various behavioural and morphological adaptations enable Pariambus typicus to live on a variety of substrates, on which the amphipod settles after contact. The highly mobile ophiuroid hosts open up new habitats for the caprellid (phoresis). Extensive grooming behaviour and specialized mouthpart morphology enable P. typicus to use detritus as an important food source, which contributes also a great part to the ophiuroids’ nutrition. The complex association between P. typicus and Ophiura is interpreted as a commensalism.

Concepts for offshore nature reserves in the southeastern North Sea

The authors summarize general criteria for selection of marine areas for protection, discuss intentions of the European Council initiative to create a coherent European network of nature reserves, point to increasing pressure on marine life by new offshore activities and installations, and arrive at preliminary proposals for offshore marine protected areas (MPAs) in the southeastern North Sea. To protect benthic communities, the minimum MPA size should not be less than 100 km2; distances of such MPAs, serving as ‘stepping-stones’ and refuges, should not exceed 100 km to guarantee coherence. Some shortcomings of the European Habitats Directive are identified and a few proposals made to consider additional marine habitat types and functional aspects within future protection initiatives.

S. V. Vassilenko and V. V. Petryashev (eds): Illustrated keys to free-living invertebrates of Eurasian Arctic Seas and adjacent deep waters. Vol. 1. Rotifera, Pycnogonida, Cirripedia, Leptostraca, Mysidacea, Hyperiidea, Caprellidea, Euphausiacea, Dendrobrachiata, Pleocyemata, Anomura, and Brachyura

The first volume of new and richly illustrated identification keys of Arctic marine invertebrates is available in English since 2009. A Russian version was published also in 2009 by KMK Scientifig Press Ltd. Moscow. The series editor is Dr. Boris I. Sirenko, chiton taxonomist, Arctic benthic ecologist and department head of the marine section of the Zoological Museum, Russian Academy of Sciences, in St. Petersburg. Volume editors are Stella Vassilenko and Victor Petryashov, known for their expertise in caprellids and mysids, respectively. The taxa contained in this volume are primarily crustacean groups with relatively few species in the Arctic plus pycnogonids and, somewhat curious, rotifers. Chapter authors (in alphabetical order) are G. A. Kolvasov (Cirripedia), L. A. Kutikova (Rotifera), V. V. Petryashov (Anomura, Euphausiacea, Leptostraca, Mysidacea), V. I. Sokolov (Dendrobranchiata and Pleocyemata—‘‘Natantia’’), E. P. Turpaeva (Pycnogonida), S. V. Vassilenko (Brachyura, Caprellidea), and M. E. Vinogradov and T. N. Semenova (Hyperiidea). About 200 species are included in this volume. Since rather few species are only recorded from the Arctic Seas not covered in this volume (and series), including the Beaufort Sea, Canadian Archipelago and parts of the central basin, the work should be rather complete, at least for the currently known species. This key and the overall series are intended to provide the international science community with tools to identify benthic and pelagic invertebrates of Eurasian Arctic seas, and to substitute the famous, but somewhat outdated work of N. S. Gaevskaya (1948). The taxonomic expertise and active Arctic taxonomic research of Russian and Ukranian scientists is the solid background of the new series, which hopefully will be completed in the foreseeable future for the roughly 5,000 invertebrate species listed in and updated from Sirenko’s (2001) ‘‘List of the species of free living invertebrates of the Eurasian Arctic Seas and adjacent deep waters’’. The English version of volume two containing various worm groups such as oligochaetes and sipunculids is well underway and will appear in 2011, and volume three (Cnidaria) is almost complete in its Russian version. If a second edition of the whole series will be planned, rearranging taxa by their taxonomic hierarchy would be desirable. Each English version goes through a peer-review process that helps bridge the sometimes apparent former communication gap between Russian and western scientists. Translation of the very specific language of taxonomic identification keys is rather challenging, but the translator’s training as an Arctic biologist and amphipod taxonomist aided in accurate wording. Each chapter contains a description of the respective taxon’s morphology and anatomy, mode of reproduction, as well as some ecological information and even remarks regarding adequate preservation and identification. The terms used in the following key portion are also explained, and in several chapters (unfortunately not in all) also marked on a schematic graph of the morphology of any given taxon. The dichotomous keys allow identifications of higher taxonomic levels as well as of families, genera and species. For each species, body size, geographic distribution, known depth range and substrate preference is given, along with the most common synonomies. Each species is illustrated with detailed black and white line drawings, E. Rachor (&) Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany e-mail: Eike.Rachor@awi.de