Piotr Kuklinski

Evolving mineralogy of cheilostome bryozoans

Abstract Cheilostomes dominate bryozoan faunas today and are the only order of bryozoans to have evolved aragonitic, calcitic, and bimineralic skeletons. New XRD analyses of 177 recent species and 34 Cretaceous–Eocene species are combined with published data to probe the mineralogical evolution of cheilostomes. This is undertaken with particular reference to the effects of the late Paleogene transition from calcite to aragonite seas believed to have been driven by the increasing Mg/Ca ratio in seawater. Aragonite was absent from all of the Cretaceous and Paleocene cheilostomes analyzed, even though most came from deposits preserving aragonitic mollusk shells, but was detected in four distantly related cheilostomes from the middle Eocene (Lutetian). Examples of cheilostomes preserved as partial molds, however, suggests that bimineralic species with aragonitic outer skeletal layers may have originated as early as the Maastrichtian. A strong latitudinal gradient was evident in cheilostome mineralogy, with the proportion of aragonitic and bimineralic recent species increasing towards the tropics. Unfortunately, relatively few low-latitude bryozoans have been described from the Cretaceous and Cenozoic fossil record, where aragonitic species are likely to be most numerous and may have their oldest occurrences. A combined database of cheilostome mineralogy shows aragonite to be widely distributed across Cheilostomata, occurring in numerous genera and families belonging to the three most diverse subgroups (Flustrina, Umbonulomorpha, and Lepraliomorpha) as well as one genus of Malacostegina. In spite of the lack of a robust phylogeny for cheilostomes, it is clear that aragonite has evolved independently on multiple occasions, the earliest acquisitions antedating the onset of aragonite seas, although apparently accelerating after this transition.

Unexpected Levels of Biological Activity during the Polar Night Offer New Perspectives on a Warming Arctic

The current understanding of Arctic ecosystems is deeply rooted in the classical view of a bottom-up controlled system with strong physical forcing and seasonality in primary-production regimes. Consequently, the Arctic polar night is commonly disregarded as a time of year when biological activities are reduced to a minimum due to a reduced food supply. Here, based upon a multidisciplinary ecosystem-scale study from the polar night at 79°N, we present an entirely different view. Instead of an ecosystem that has entered a resting state, we document a system with high activity levels and biological interactions across most trophic levels. In some habitats, biological diversity and presence of juvenile stages were elevated in winter months compared to the more productive and sunlit periods. Ultimately, our results suggest a different perspective regarding ecosystem function that will be of importance for future environmental management and decision making, especially at a time when Arctic regions are experiencing accelerated environmental change [1].

Factors influencing hydroids (Cnidaria: Hydrozoa) biodiversity and distribution in Arctic kelp forest

The biodiversity and distribution patterns of epiphytic hydroids were studied in kelp forests (composed of Laminaria digitata, Saccharina latissima and Alaria esculenta ) located in an Arctic glaciated fiord (Hornsund, west Spitsbergen). In total, twenty-eight species were found colonizing algae, stones connected to holdfast, and overgrowing the surface of other animals associated with kelps. The characteristics of the algal host (e.g. algae species, age, rhizoid volume or biomass) did not show any effect upon hydroid species richness or species composition. High hydroid biodiversity was strongly dependent on microsubstrate heterogeneity. The highest biodiversity as well as frequency of hydroid occurrence were noted at a site located furthest from the glacier and characterized by the lowest sediment concentration and sedimentation rate. Sexual reproduction also seemed to be inhibited by glacier-derived disturbance. Of ten fertile species found at the ‘clearest’ site only two were fertile at sites under the strong influence of such perturbations. Potential physical drivers of species occurrence were linked to the activity of tidal glaciers, particularly to high loads of mineral sedimentation and iceberg scouring.

Seasonality of occurrence and recruitment of Arctic marine benthic invertebrate larvae in relation to environmental variables

The Arctic system is one of the regions most influenced by ongoing global climate change, but there are still critical gaps in our knowledge regarding a substantial number of biological processes. This is especially true for processes taking place during the Arctic winter but also for seasonal processes, such as the dynamics of intra-annual meroplankton occurrence. Here, we report on a 1-year study of meroplankton seasonal variability from a fjordic system in the Arctic Archipelago of Svalbard. The study combines an examination of phytoplankton, zooplankton, and hard bottom benthic settlement with measurements of environmental parameters (e.g., water temperature, particulate organic matter, and dissolved organic carbon). Samples were taken on a bi-weekly or monthly basis, and a total of 11 taxa representing six phyla of meroplankton were recorded over a 1-year period from January to December 2007. The occurrence of benthic larvae varied between the seasons, reaching a maximum in both abundance and taxon richness in late spring through early summer. Meroplanktonic larvae were absent in winter. However, settlement of benthic organisms was also recorded during the winter months (February and March), which indicates individual trade-offs related to timing of reproduction and competition. In addition, it suggests that these larvae are not relying on higher summer nutrient concentrations, but instead are dependent on alternative food sources. In parallel with meroplankton abundance, all other measured parameters, both biological (e.g., phyto- and zooplankton abundance and diversity) and physical (e.g., particulate organic matter), exhibited seasonal variability with peaks in the warmer months of the year.

Biodiversity patterns of macro-epifauna on different lamina parts of Laminaria digitata and Saccharina latissima collected during spring and summer 2004 in Kongsfjorden, Svalbard

The epifauna associated with two of the most common species of kelp in the Arctic, Laminaria digitata (Hudson) Lamouroux, 1813 and Saccharina latissima (Linnaeus) Lane, , Mayes, Druehl and Saunders 2006 [synonym: L. saccharina (Linnaeus) Lamouroux, 1813] were examined in Kongsfjorden, Svalbard. The aim of this study was to test whether species richness of epifauna was influenced by seasonality of recruitment supply (spring and summer) or by age of the substrate (lamina). From 20 algae specimens (ten—L. digitata, ten—S. latissima), a total of 27 epifaunal taxa were identified with bryozoans as the most species-rich group. Total species richness ranged from one to nine species per lamina. No significant difference in species richness was observed between the two kelp species. In both macroalgae, more epifauna taxa were registered on lamina in May (mean 6) than in August (mean 3). This indicates that the time chosen for sampling had a significant impact on the species richness pattern. The number of epifaunal species was significantly negatively correlated with increasing age of the lamina. There are indications that diversity of the epifauna on lamina is influenced to a large extent by substrate (lamina) surface area, environmental stress and the presence of meroplankton in the water column.

Microhabitat diversity of Svalbard Bryozoa

Bryozoans are one of the major macrofaunal groups of the high polar regions. Here we present data on the nature of bryozoan assemblages in the Svalbard Archipelago sampled over 6 years between 1997 and 2002. Samples were collected with use of Van Veen grab, dredge and Scuba diving at depths ranging from 0 to 268 m. Among examined material (5026 items) bryozoans were present on one type of abiotic (stones) and 40 types of biotic substrata. The biotic substrata we investigated included algae (12 taxa) and invertebrates (28 taxa: Hydrozoa, Gastropoda, Bivalvia, Polychaeta, Crustacea, Ascidiacea, other Bryozoa). Both a priori ANOSIM (Global R = 0.512, P = 0.001) and cluster analyses reveal differences between the assemblages on different types of substrata. Cluster analyses distinguish two distinct groups of substrata. The first (stable) included stones, molluscs and Balanus balanus whilst the second (flexible) consisted of algae, hydrozoans and bryozoans. Bryozoan assemblages which colonized different substrata, varied in terms of species composition and their dominance. Bryozoan species were categorized as generalists, low‐specificity epibiotic species or locally abundant background species. No species were found to be substratum‐specific to any type. Among substrata with the richest bryozoan fauna were stones (156 taxa), Chlamys islandica (68) and Balanus balanus (62). There were clear patterns in the distribution of substrata colonized by bryozoans within the fjord system: those shallow near the mouth were rich whilst those in deeper water were depauperate. We consider environmental gradients such as siltation and processes related to depth to be responsible for such patterns.

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.

Trends in the Diversity, Distribution and Life History Strategy of Arctic Hydrozoa (Cnidaria)

This is the first attempt to compile a comprehensive and updated species list for Hydrozoa in the Arctic, encompassing both hydroid and medusa stages and including Siphonophorae. We address the hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic by Hydrozoa after the Last Glacial Maximum. Presence-absence data of Hydrozoa in the Arctic were prepared on the basis of historical and present-day literature. The Arctic was divided into ecoregions. Species were grouped into distributional categories according to their worldwide occurrences. Each species was classified according to life history strategy. The similarity of species composition among regions was calculated with the Bray-Curtis index. Average and variation in taxonomic distinctness were used to measure diversity at the taxonomic level. A total of 268 species were recorded. Arctic-boreal species were the most common and dominated each studied region. Nineteen percent of species were restricted to the Arctic. There was a predominance of benthic species over holo- and meroplanktonic species. Arctic, Arctic-Boreal and Boreal species were mostly benthic, while widely distributed species more frequently possessed a pelagic stage. Our results support hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic. The predominance of benthic Hydrozoa suggests that the Arctic could have been colonised after the Last Glacial Maximum by hydroids rafting on floating substrata or recolonising from glacial refugia.

Arctic species of the cheilostome bryozoan Microporella, with a redescription of the type species

This investigation focuses on the diversity and taxonomy of species of Microporella found north of the Arctic Circle. Firstly, however, a neotype is chosen for the Mediterranean type species M. ciliata (Pallas) in order to stabilize the taxonomy of this “pseudocosmopolitan” species, which has been recorded in the past from the Arctic. Study of type and other material using scanning electron microscopy shows that only two Arctic species of Microporella can be recognized, M. arctica Norman and M. klugei sp. nov. The first of these is characterized by a large ascopore divided by thin radial septa and situated close to the proximal rim of the orifice. Microporella klugei sp. nov. differs in having a smaller, undivided ascopore situated in a more proximal position on the frontal shield. Both Arctic species are notable among Microporella species for having a high proportion of autozooids without associated avicularia.

A new genus and three new species of Antarctic cheilostome Bryozoa

Three new cheilostome bryozoans species were discovered in the collections of the BIOPEARL I cruise to the Scotia Arc. The species were found on boulders from the continental slope and shelf-break of Powell Basin, South Georgia and Shag Rocks in Agassiz trawl catches from the RRS James Clarke Ross. Amphiblestrum henryi sp. nov. is characterised by a conspicuous avicularium acute to the frontal surface overarching more than half of the opesia. On the distobasal edge of the avicularium there are 1–4 processes pointed distally and distolaterally. Inferusia taylori gen. et sp. nov. is characterised by a reduced gymnocyst, extensive costate frontal shield, and an avicularium distal of the orifice. Antarctothoa haywardi sp. nov. has three types of zooids: autozooids, male and female, the males possessing a tiny orifice in relation to zooid size. The species is very similar to Antarcothoaalia but the shape of the autozooidal orifice, with its deeper and narrower sinus, as well as a lack of condyles in the proximal corners of the male orifice allow the species to be recognized as new.