Crustose coralline algal species host distinct bacterial assemblages on their surfaces

Crustose coralline algae (CCA) are important components of many marine ecosystems. They aid in reef accretion and stabilization, create habitat for other organisms, contribute to carbon sequestration and are important settlement substrata for a number of marine invertebrates. Despite their ecological importance, little is known about the bacterial communities associated with CCA or whether differences in bacterial assemblages may have ecological implications. This study examined the bacterial communities on four different species of CCA collected in Belize using bacterial tag-encoded FLX amplicon pyrosequencing of the V1–V3 region of the 16S rDNA. CCA were dominated by Alphaproteobacteria, Gammaproteobacteria and Actinomycetes. At the operational taxonomic unit (OTU) level, each CCA species had a unique bacterial community that was significantly different from all other CCA species. Hydrolithon boergesenii and Titanoderma prototypum, CCA species that facilitate larval settlement in multiple corals, had higher abundances of OTUs related to bacteria that inhibit the growth and/or biofilm formation of coral pathogens. Fewer coral larvae settle on the surfaces of Paragoniolithon solubile and Porolithon pachydermum. These CCA species had higher abundances of OTUs related to known coral pathogens and cyanobacteria. Coral larvae may be able to use the observed differences in bacterial community composition on CCA species to assess the suitability of these substrata for settlement and selectively settle on CCA species that contain beneficial bacteria.     

Late Miocene ostracod assemblages from eastern Mediterranean coral reef complexes (central Crete,Greece)

Ostracods from ten Late Miocene coral reef complexes built by Siderastrea, Tarbellastrea and Porites, cropping out in the Messara Plain (southern Iraklion basin, central Crete), have been investigated and five assemblages have been recognised, which point to different marine environments: (1) assemblage from the basal sandy silts, dominated by very shallow inner-infralittoral species, such as Cyamocytheridea meniscus, Cyamocytheridea obstipa, Cyamocytheridea dertonensis, Cytheretta semiornata and Nonurocythereis seminulum; (2) assemblage from the coral reef complexes within which Grinioneis haidingeri, Aurila cicatricosa, Cimbaurila diecii, Tenedocythere cruciata, Pokornyella italica and Callistocythere quadrangula are dominant and point to a stable inner-infralittoral environment characterised by warm, quiet and well-oxygenated waters; (3) assemblage from the silts intercalated among the coral reef complexes, mainly characterised by Neomonoceratina laskarevi, Cytheridea acuminata, Phlyctenophora farkasi and Aurila albicans together with Callistocythere spp., Xestoleberis communis and Xestoleberis dispar, which points to a very shallow marine environment rich in aquatic vegetation; (4) assemblage from the upper silts, which records the absolute dominance of Xestoleberis species, reflecting a very shallow and highly-vegetated environment and (5) assemblage from the uppermost silty clays, dominated by Hemicytherura defiorei, Xestoleberis spp. and Palmoconcha dertobrevis, accompanied by Acanthocythereis hystrix, Cytherella scutulum, Bairdoppilata conformis, Semicytherura spp., Krithe sp., Cytheropteron alatum, Bythocypris sp. and Pseudocythere caudata, which suggest deeper marine environments probably located in the outer infralittoral/inner-circalittoral zones. The studied section has been dated by means of calcareous nannoplankton to be not younger than Zone MNN9 (Early Tortonian), which is the biostratigraphical datum recorded in the fine-grained deposits that overlie the coral reef complexes. An age not older than Tortonian can be inferred by the stratigraphical distribution of the recognized ostracods. Thus, the coral reef complexes have been tentatively referred to the Early Tortonian.     

Changes in habitat complexity negatively affect diverse gastropod assemblages in coralline algal turf

The physical structure of a habitat generally has a strong influence on the diversity and abundance of associated organisms. I investigated the role of coralline algal turf structure in determining spatial variation of gastropod assemblages at different tidal heights of a rocky shore near Sydney, Australia. The structural characteristics of algal turf tested were frond density (or structural complexity) and frond length (the vertical scale over which structural complexity was measured). This definition of structural complexity assumes that complexity of the habitat increases with increasing frond density. While frond length was unrelated to gastropod community structure, I found significant correlations between density of fronds and multivariate and univariate measures of gastropod assemblages, indicating the importance of structural complexity. In contrast to previous studies, here there were negative relationships between the density of fronds and the richness and abundance of gastropods. Artificial habitat mimics were used to manipulate the density of fronds to test the hypothesis that increasing algal structural complexity decreases the richness and abundance of gastropods. As predicted, there were significantly more species of gastropods in loosely packed than in tightly packed turf at both low- and mid-shore levels. Despite large differences between gastropod assemblages at different tidal heights, the direction and magnitude of these negative effects were similar at low- and mid-shore levels and, therefore, relatively independent of local environmental conditions. These novel results extend our previous understanding of the ecological effects of habitat structure because they demonstrate possible limitations of commonly used definitions of structural complexity, as well as distinct upper thresholds in the relationship between structural complexity and faunal species richness.     

Regional differences in kelp-associated algal assemblages on temperate limestone reefs in south-western Australia

Abstract. Ecklonia radiata (C. Agardh) J. Agardh kelp beds — a characteristic feature of the nearshore environment along the south‐west Australian coastline — contribute significantly to the coastal biodiversity in temperate Australia, yet, little is known about the organization of these macroalgal assemblages. By compiling existing and new data sets from habitat surveys, we have characterized and compared the structure of kelp‐associated macroalgal assemblages in three regions (Marmion Lagoon, Hamelin Bay and the marine environment neighbouring the Fitzgerald River National Park) across more than 1000 kilometres of the south‐west Australian coastline. 152 macroalgal taxa had been recognized within the three regions and this is in the range of species richness reported from other Australian and African kelp beds. The kelp‐associated algal assemblages were regionally distinct, 66% of all taxa were only found in one region and only 17 taxa were found in all three regions. Adjacent regions shared an additional 13–15 taxa. The regional shifts in assemblage structure were evident in species composition of both canopy and understorey. The organization of assemblages followed a spatial hierarchy where differences in assemblage structure were larger among regions (hundreds of kilometres apart) than among sites within regions (kilometres apart) and differences among sites within region were larger than differences among quadrats within sites (metres apart). Despite this hierarchy each level of nesting contributed approximately the same to total variation in assemblage structure and these spatial patterns were stronger than temporal differences from seasons to 2–3 years. Our results suggest that local and small‐scale processes contribute considerably to heterogeneity in macroalgal assemblages throughout south‐western Australia, and, in particular, our results are consistent with E. radiata exerting a strong influence on macroalgal assemblage structure. Further, our study contradicts the existence of a general south‐west Australian kelp assemblage, although a few species may form the core of E. radiata associations across regions.     

Influence of UV radiation on growth of sporelings of three non-geniculate coralline red algae from Southern Iberian Peninsula

The effects of UV radiation (UVR) on growth of sporelings of Melobesia membranacea (Esper) Lamouroux, Lithophyllum incrustans Philippi and Mesophyllum lichenoides (Ellis) Lemoine, were investigated by culturing the algae under different doses of photosynthetically active radiation (PAR) only and PAR + UVR. Under natural conditions, the light fields occurring in the habitats of the three species differ substantially. Whereas M. lichenoides and L. incrustans inhabit sun‐exposed places in the eulittoral and upper part of the sublittoral, M. membranacea grows as an epiphyte in shady crevices in the eulittoral, where irradiance is < 10% of that in sun‐exposed places. The relative growth rate (RGR) of sporelings of these non‐geniculate coralline algae was affected by the UVR. The extent of harmful UVR effects on growth rate showed a similar increase as a function of the logarithm of the dose in the three species, inferred by a similar slope in all the linear regressions for a given action spectrum. The inhibition of growth under the PAR + UVR showed similar features in the two species of non‐geniculate coralline species from sun‐exposed places, that is, similar intercepts and slopes in the linear regressions of RGR as a function of the logarithm of the biologically effective dose.     

Middle Miocene warm-temperate carbonates of Central Paratethys (Mt. Zrinska Gora, Croatia): paleoenvironmental reconstruction based on bryozoans, coralline red algae, foraminifera, and calcareous nannoplankton

Carbonate deposits from Zrin in the Mt. Zrinska Gora were deposited in the SW part of the Central Paratethys Sea during the Middle Badenian (Middle Miocene). The studied section contains a rich fossil community of non-geniculate coralline red algae (Subfamily Melobesioideae), bryozoans, benthic and planktonic foraminifera, echinoderms, ostracods, molluscs, and calcareous nannoplankton. Based on lithological variations and changes in the biogenic components, four facies associations (FA) are distinguished. Their distribution points to skeletal production and sedimentation on a middle to proximal outer carbonate ramp. The main lithological feature of the section is an alternation of two lithofacies: fully lithified grainstone–rudstone and packstone, and semi-lithified rudstone–floatstone with a carbonate sandy matrix. Depositional environments on the ramp were periodically influenced by minor high-frequency sea-level changes and/or changes of hydrodynamic conditions, which are suggested as the driving mechanisms causing the alternation of the two lithofacies. Vertically in the succession, the two lithofacies alternate to give three thinning- and fining-upward units. The lower part of each unit is formed of a rhodolith and coralline algal FA, which passes upwards into a bryozoan-coralline algal FA and/or FA of bioclastic packstone-grainstone. Based on the vertical upward change in FAs, each unit can be interpreted as a deepening-upward sequence. Patterns in the relative abundance of bryozoan colony growth form (vinculariiform, cellariiform, adeoniform, membraniporiform, celleporiform, and reteporiform), size and abundance of rhodoliths and coralline branches, and benthic foraminifera are interpreted by comparison with data from modern and fossil environments. Based on these data, a water depth range for each FA is interpreted, providing evidence of low-frequency relative sea-level changes. It is hypothesized that relative sea-level fluctuated in the water depth range from 30 to 80 m, and in the uppermost part of the section, rich in planktonic foraminifera and calcareous nannoplankton, possibly deeper. Causes of the low-frequency relative sea-level fluctuations and the general deepening trend observed within the succession cannot be interpreted based on one section; however, they may be related to the subsidence of the depositional basin. The benthic biotic communities are a vertical alternation of rhodalgal and bryorhodalgal associations, and this is attributed to relative sea-level fluctuations. These biotic associations gave rise to warm-temperate carbonates of the Middle Badenian N9 planktonic Zone (Orbulina suturalis, O. universa) and NN4–NN5 nannoplankton Zones (Sphenolithus heteromorphus).     

Spatial variation in molluscan assemblages from coralline turfs of Argentinean Patagonia

Patterns of spatial variation of molluscan communities associatedwith coralline algal turfs were evaluated over 1,000 kmof the coast of Argentinean Patagonia. A hierarchically-nestedexperimental design was used to determine the relative importanceof molluscan assemblage variation at three different spatialscales (shores, sites and cores). Hypotheses were also testedabout the potential role of habitat variables (frond density,frond length, sediment and epiphytes) for determining molluscancommunity structure. In total, 38 molluscan species were foundcomprising 16, 18 and 4 species of bivalves, gastropods andpolyplacophorans, respectively. Densities of molluscs in corallineturfs reached ca 77,000 individuals per m² and were dominatedby mussels, especially Perumytilus purpuratus. Multivariateand univariate analyses of assemblage structure consistentlyshowed that variation at scales of metres and hundreds of kilometresdominated, with sites 20–50 m apart always contributingless than 24% of the total. Significant associations betweenmolluscan community structure and both frond density and frondlength demonstrated the potential importance of habitat structurein determining community structure at local scales. Variationin molluscan assemblages at the scale of shores, however, didnot appear to correlate with latitudinal, temperature or waveexposure gradients, indicating that other processes must beoperating. The compositions of molluscan assemblages in corallineturfs on the coast of Argentina were similar to those reportedfor central Chile. Comparisons of the richness of these SouthAmerican assemblages to other parts of the world revealed somestriking biogeographical patterns that warrant further investigation.Overall, this work highlights the general importance of small-scalevariation in molluscan assemblages on rocky shores and the consistentinfluence of habitat complexity in determining the structureof diverse molluscan communities associated with mat-like habitats. (Received 10 August 2006; accepted 20 January 2007)     

Does colonization contribute to spatial patterns of common invertebrates in coralline algal turf?

Abstract The potential of colonization to contribute to the spatial patterns of six common invertebrates in coralline algal turf was investigated on a rocky shore near Sydney, Australia. The species, which included two amphipods (Elasmopus warra, Hyale spp.), a small bivalve (Lasaea australis), a fly larva (Limonia marina), and two microgastropods (Amphithalamus incidata and Eatoniella atropurpurea), had a range of dispersal modes (larval dispersal, crawling, swimming, rafting, and passive transport). Field sampling between May 1997 and November 1999 demonstrated that the amphipods were more abundant in low‐shore areas, the fly larvae and bivalves were more abundant in mid‐shore areas, and the abundances of gastropods did not vary with tidal height. Furthermore, abundances of all species varied among patches separated by tens of metres at one time or another. To test whether rates of colonization could contribute to established patterns of abundance, habitat mimics were deployed for 2‐week periods. The supply of new individuals matched long‐term patterns of abundance at different tidal heights for E. warra and L. marina. Colonization rates also differed among patches separated by tens of metres for three of the six species. Overall, there was little evidence to suggest that common species in coralline turf are limited by colonization on local scales, regardless of their major mode of dispersal. However, the potential for colonization to determine patterns of abundance varied from species to species.     

Disentangling the roles of spatial and environmental variables in shaping benthic algal assemblages in rivers of central and northern China

Benthic algae were collected from central and northern Chinese rivers to test the hypothesis that geographic location has significant contributions in shaping algal assemblages. We used Moran’s eigenvector maps (MEM) to model spatial components and variation partitioning to quantify the influences of spatial and environmental variables on regional patterns of algal richness and community composition, respectively. We found that variation in algal richness was attributed to MEM component 2, 8, and 9 and the quadratic term of N–NO₃. Regarding abundance data, latitude, longitude, and MEM component 1, 2, and 7 were important spatial variables. Although P–PO₄, pH, and annual mean temperature were significant environmental variables influencing algal community composition, they were all spatially structured. Among the total explained variance in both algal metrics, spatial proportions were higher than that of environmental variables. We also found that abundant species of Achnanthidium minutissimum, Cocconeis placentula, Cymbella delicatula, Cymbella affinis, Cymbella turgidula, and Synedra ulna displayed clear spatially related patterns. In conclusion, the contributions of spatial and environmental variables to regional variation of algal assemblages are scale-dependent. As for our study scale (~1,000 km), spatial control may be more important. Since spatial effects could obscure local environmental impacts on algal communities, appropriate study scale and statistical methods should be taken into account in algal bioassessment. We recommend inclusion of both algal richness and community composition in study of algal biogeography, due to their different relationships with spatial and environmental variables.     

Palaeoenvironmental and palaeoclimatic reconstruction of the Middle to Late Pleistocene sequence of Scladina Cave (Namur,Belgium) using the small-mammal assemblages

The habitat weighting, the bioclimatic model methods and the Simpson diversity index are applied to the small-mammals assemblage of Scladina Cave (border between High and Middle Belgium) in order to reconstruct the environmental and climatic fluctuations that are reflected on the Middle to Late Pleistocene sequence of the cave. The small-mammal data analyzed come from two surveys carried out at the entrance of the cave and allow us to identify within the section one cold episode: a dry, cool phase in the upper part of the sequence (probably associated with the MIS 3). The environmental and climatic data show an alternation of open meadows and woodland formations through both sequences, punctuated by peaks in local watery environments together with lower temperatures and higher precipitations rates than at present. Finally, a comparison of the small-mammal fossil assemblage from the studied surveys with the small-mammals assemblage from the Holocene deposits of Scladina Cave shows that layers related with MIS 5 temperate sub-stages (MIS 5c and MIS 5a) present environmental characteristics similar to those prevailing nowadays (a landscape dominated by woodland formations and water streams) in the area surrounding the cave. This is coherent with the available chronostratigraphic datasets on this part of the sequence, suggesting the record of the humid and temperate phases at the beginning of the Late Pleistocene.     

Bioerosion of gastropod shells: with emphasis on effects of coralline algal cover and shell microstructure

Organisms boring into fifty nine species of gastropod shells on reefs around Guam were the bryozoan Penetrantia clionoides; the acrothoracian barnacles Cryptophialus coronorphorus, Cryptophialus zulloi and Lithoglyptis mitis; the foraminifer Cymbaloporella tabellaeformis, the polydorid Polydora sp. and seven species of clionid sponge. Evidence that crustose coralline algae interfere with settlement of larvae of acrothoracian barnacles, clionid sponges, and boring polychaetes came from two sources: (1) low intensity of boring in limpet shells, a potentially penetrable substrate that remains largely free of borings by virtue of becoming fully covered with coralline algae at a young age and (2) the extremely low levels of boring in the algal ridge, a massive area of carbonate almost entirely covered by a layer of living crustose corallines. There was a strong negative correlation between microstructural hardness and infestation by acrothoracian barnacles and no correlation in the case of the other borers. It is suggested that this points to a mechanical rather than a chemical method of boring by the barnacles. The periostracum, a layer of organic material reputedly a natural inhibitor of boring organisms, was bored by acrothoracican barnacles and by the bryozoan. The intensity of acrothoracican borings is shown to have no correlation with the length of the gastropod shell.     

Responses of epibenthic algal assemblages to water abstraction in Hong Kong streams

We studied the effects of flow reduction on epibenthic algal assemblages by comparing up- and down-stream reaches of ten Hong Kong streams subject to different degrees of water abstraction during 2007–2008. Downstream discharge declined by 71 and 54% during the wet and dry seasons, respectively. Algal responses varied seasonally and according to morphological guild and reflecting reductions in discharge and current velocity, or changes in total nitrogen and phosphate, or their combined effects. Significant inter-reach assemblage differences were observed during the both seasons, but wet-season assemblage structure was not directly influenced by any flow-related variable. During the dry season, scouring-tolerant prostrate/adnate diatoms (especially Achnanthes, Cocconeis) were relatively abundant upstream, whereas intolerant stalked (Eunotia, Gomphonema) and mobile diatoms were more numerous downstream. Both low- and high-profile (erect diatoms, Chamaesiphon, Calothrix) guilds were sensitive to changes in nutrients. Low-flow conditions downstream, surprisingly, enhanced algal diversity, and richness. Based on the linear response of Cocconeis (mainly C. placentula) to discharge reduction, we recommend that >65% of dry-season discharge should be maintained in downstream reaches in order to sustain near-natural algal assemblages; 32% of discharge is required to avoid substantial alterations in assemblage structure.     

A new view on Nematothallus: coralline red algae from the Silurian of Gotland

Abstract:  The thalloid carbonaceous fossil Nematothallus Lang, 1937, has been widely interpreted as an early Palaeozoic land‐plant, despite the absence of a convincing modern analogue. Exceptionally well‐preserved nematophyte cuticle from the Late Silurian Burgsvik Sandstone Formation, Gotland provides additional insight into the organism’s anatomy, phylogenetic affiliations and ecology. Because this material exhibits additional characters not present in the type material we assign it to Nematothallopsis gotlandii gen. et sp. nov. The organism was constituted of a close‐packed layer of palisade‐like filaments covered by a cuticle that bears a characteristic pseudocellular pattern on its inner surface. Apertures in this cuticle are often encircled by a ring of multicellular filaments, which are sometimes associated with spheroidal, spore‐like entities. In the light of the conspicuous similarity of the palisade layers to the pseudoparenchymatous tissue of coralline red algae, and of the filament‐fringed apertures to their reproductive conceptacles, we reconstruct the Nematothallopsis organism as an extinct rhodophyte and re‐evaluate the putative terrestrial habit of cuticular nematophytes in general.     

Centipede assemblages along an urbanization gradient in the city of Heraklion,Crete (Greece)

Global urbanization is a major force that causes alteration and loss of natural habitats. Urban ecosystems are strongly affected by humans and there is a gradient of decreasing human influence from city centers to natural habitats. To study ecological changes along this continuum, researchers introduced the urban-rural gradient approach. The responses of centipedes to an urbanization gradient (urban-suburban-rural areas) were studied using pitfall traps in and near the city of Heraklion, in the island of Crete, Greece, from November 2010 to November 2011. Our results do not support the intermediate disturbance hypothesis, in which suburban areas located in the transitional zone between urban and rural habitats failed to indicate significant increase in terms of species richness and diversity.     

Influence of drought on algal biofilms and meiofaunal assemblages of temperate reservoirs and rivers

The role of hydrological droughts in shaping meiofauna abundance through alterations in biofilm biomass and composition was investigated. In January 2005, continental Portugal was under a moderate to severe drought resulting from a 40% to 60% decrease in rainfall during the previous 12 months relative to the long-term average (1961–1990). Reservoir capacity was reduced by 30–50% relative to average values and the width of streams was reduced by 20–80% in the Zêzere River Basin (central Portugal). Algal biomass and algal class composition of biofilms was assessed through quantification of algal pigments in three reservoir and six river locations. During drought, habitat alterations are expected to be sharp in rivers while, in the absence of water quality deterioration, the habitat characteristics of reservoirs are expected to remain fairly unaffected. Chlorophylls and carotenoid pigments were extracted from biofilm samples and analysed using high performance liquid chromatography (HPLC). In the winter of 2003, during the period of average rainfall, biofilm biomass did not exceed 5 μg chlorophyll a cm⁻² at any location. River biofilm biomass was roughly half of that measured in the reservoirs. In the winter of 2005 (drought), biofilm biomass increased by more than 5-fold in river locations and remained low or decreased in the reservoirs. Algal biofilms were either dominated by Bacillariophyceae or by Chlorophyceae regardless of the existence of drought. The relative contribution of Bacillariophyceae to total biofilm biomass was higher during the drought than under average hydrological conditions. The abundance of harpacticoids, cladocerans and ostracods was favoured by the drought only in the reservoirs where an increase in diatom proportion in biofilms was observed. The increase in the abundance of cyclopoid copepods, turbellarians, nematodes and chironomids in rivers during the drought could be explained by algal class composition and biomass of biofilms and environmental variables (organic matter sediment content, phosphorus availability content and sediment granulometry). The hydrological drought appears to regulate meiofauna abundance only in river locations, possibly through the promotion of the growth of biofilms and the availability of organic matter deposited in rivers during the drought. Handling editor: D. Ryder     

Miocene snakes from northeastern Kazakhstan: new data on the evolution of snake assemblages in Siberia

Abstract

The Neogene snake fauna from the central and eastern regions of Eurasia is still largely unknown. This paper reports on a unique snake fauna from the late middle Miocene of the Baikadam and Malyi Kalkaman 1 and 2 localities, northeastern Kazakhstan, which represents the best-documented Miocene snake assemblage in Central Asia. Previous studies admitted that snake fauna could be homogeneous over a large part of Eurasia during the Miocene, with the late middle to early late Miocene assemblages similar to snake assemblages that inhabited Europe in the late early and early middle Miocene. This assumption is partially supported by the presence of Texasophis bohemiacus and Coluber cf. hungaricus, as well as vipers of the ‘V. aspis’ complex. However, the presence of taxa which are (1) probably not related to European representatives (‘Colubrinae’ A and B), (2) probably never occurred in Central and Western Europe and (3) are closely related to species recently inhabiting southern Siberia (Elaphe aff. dione, Gloydius sp.) indicates that faunal dissimilarity was relatively high within Eurasia during the late middle Miocene. This assumption is in accordance with studies of small mammal assemblages which show a decreasing homogenity in the Eurasia in the course of the middle Miocene.     

Lizard assemblages in a fragmented landscape of central Chile

We studied lizard assemblages assessing abundance, richness, and nestedness in a fragmented landscape of central Chile including native temperate forest, forest fragments, and commercial pine plantations. Fragmentation and plantations increase the availability of edge habitats triggering both the support of additional lizard species, absent at the continuous forest, and the nestedness of lizard assemblages, where interior habitats of forest and plantations are nested subsets of habitat edges. A vulnerable lizard (Liolaemus tenuis) thrives at fragments in abundance similar to the continuous forest. Therefore, remnants ought to be considered in the conservation of lizard assemblages.     

Differential effects of native and invasive algal wrack on macrofaunal assemblages inhabiting exposed sandy beaches

Many sandy beaches worldwide receive large amounts of drift seaweed, known as wrack, from offshore algal beds and closer rocky intertidal shores. Despite the important influence of algal wrack on macrofaunal assemblages from different coastal systems, relatively little attention has been paid to the macrofaunal responses in sandy beaches to macrophyte wrack supplies. Algal wrack is a key resource, i.e. for food and/or refuge, for beach invertebrates while its availability can affect diversity and abundance of intertidal animals including shorebirds, but the role of certain types of wrack and its location on the shore has not been examined experimentally to date. In this paper, we use experimental manipulation of two species of brown seaweeds, i.e. artificial wrack patches made up of the native macroalgae Saccorhiza polyschides and the invasive species Sargassum muticum, to test hypotheses about influences on macrofaunal assemblages inhabiting the drift line and supratidal levels of exposed beaches. Results pointed out that different types of wrack deposits were not used uniformly by invertebrates. Nutritional value differed between the two species of wrack. In most cases, the carbohydrates, lipids and organic carbon content were greater in patches of S. muticum than in patches of S. polyschides. Data also provided evidences that nutritional content and microclimatic conditions of wrack deposits, i.e. temperature and humidity, might affect macrofaunal assemblages.     

Late Miocene vegetation and climate reconstruction based on pollen data from the Sofia Basin (West Bulgaria)

The analysis of fossil palynomorh assemblages in the Late Miocene freshwater sediments of the Sofia Basin (West Bulgaria) was done to collect data on the vegetation and climate dynamics during the Late Miocene. On the basis of pollen data, we described the main palaeocomunities developed in the region. The mixed mesophytic forests dominated the vegetation in which species of Quercus, Ulmus, Zelkova, Fagus, Carpinus, Betula, Castanea, Corylus, Pterocarya, Carya, Juglans, and Eucommia played important roles. Swamp forests were also recorded, including Taxodiaceae, Alnus, Glyptostrobus, Nyssa, and Myrica. Herbaceous vegetation was distributed in the middle part of the section, with a maximum of 35.5%. The vegetation dynamic passes through several phases, which were associated with changes in paleoclimate and palaeoecological conditions. Coexistence Approach (CA) was applied to palynological data to calculate four climatic parameters. The values of coexistence intervals for mean annual temperatures are 13.6–16.6 °C, with winter temperatures being 3.7–6.6 °C and summer temperatures being 23.6–27.8 °C. Mean annual precipitation ranged most frequently between 828 and 1308 mm. The palaeoclimatic reconstruction illustrates existence of a warm-temperate and relatively humid climate with higher mean annual temperature than the present day climate.