Dinoflagellate cysts of ODP Leg 101 holes

The Albian-Cenomanian sediments in Holes 627B and 635B contain diverse dinoflagellate-cyst assemblages, which show affinities with coeval assemblages from offshore Morocco and northwest Europe. A total of 34 samples were analyzed from the shallow-water platform sediments and neritic marly chalk of Hole 627B and from the argillaceous chalk and limestone of Hole 635B. Dinoflagellate cysts indicate that the top of the shallow-water platform drilled at Hole 627B must be attributed to the late Albian. Dinocysts also date the drowning of the carbonate platform of the Blake Plateau. This drowning started in the latest Albian (Vraconian) and continued into the Cenomanian. The site area changed from an inner to intermediate or outer(?) neritic environment. The area around Hole 635B from the late Albian appears to have been situated in a deeper environment than the area around Hole 627B during the same period. The new dinoflagellate-cyst species Compositosphaeridiuml bahamaensis n. sp., Maghrebinia breviornata n. sp., and Subtilisphaeral habibi n. sp. are described, and Pervosphaeridium truncatum is emended. Additional taxonomic remarks about other species are included.

Abundances of dinoflagellate cysts in sediment trap MST-9 (Appendix 1)

To study the ecology of calcareous dinoflagellates we examined the impact of the SW and NE monsoons on cyst formation using sediment trap material, collected at 1032 m water depth, off Somalia from June 1992 to February 1993. The results do not confirm the relationship between cyst production and lower nutrient concentrations, as highest cyst fluxes were recorded during late SW monsoon under the relatively nutrient-rich and less agitated conditions of mature upwelled water. Lowest cyst fluxes were found under strongly stratified, nutrient-depleted surface waters during the inter-monsoon. Although all of the studied species seem to prefer a stratified water column, an elevated concentration of nutrients appears to be necessary to maintain high cyst production. Comparison of the mean cyst flux to the sediment trap with that into the underlying surface sediments reveals a loss of 81-96%, which can be attributed to calcite dissolution. The relatively small spheres of Thoracosphaera heimii are affected more than the cysts of the other species.

Late Holocene pollen and organic walled dinoflagellate cysts analyses of sedimet cores from the Java Sea

The pollen, spore and organic walled dinoflagelletas cyst associations of two marine sediment cores from the Java Sea off the mouths of Jelai River (South Kalimantan) and Solo River (East Java) reflect environment and vegetation changes during the last ca 3500 years in the region. A decline in primary forest taxa (e.g. Agathis, Allophylus, Dacrycarpus, Dacrydium, Dipterocarpaceae, Phyllocladus, and Podocarpus) suggest that the major change in vegetation is caused by the forest canopy opening that can be related to human activity. The successively increase of pollen of pioneer canopy and herb taxa (e.g. Acalypha, Ficus, Macaranga/Mallotus, Trema, Pandanus) indicate the development of a secondary vegetation. In Java these changes started much earlier (ca at 2950 cal yr BP) then in Kalimantan (ca at 910 cal yr BP) and seem to be more severe. Changes in the marine realm, reflected by the dinoflagellate cyst association correspond to changes in vegetation on land. They reflect a gradual change from relatively well ventilated to more hypoxic bottom/pore water conditions in a more eutrophic environment. Near the coast of Java, the shift of the water trophic status took place between ca 820 and 500 cal yrs BP, while near the coast of Kalimantan it occurred as late as at the beginning of the 20th century. We observe an increasing amount of the cyst of Polykrikos schwarzii, cyst of P. kofoidii, Lingulodinium machaerophorum, Nematosphaeropsis labyrinthus and Selenopemphix nephroides at times of secondary vegetation development on land, suggesting that these species react strongly on human induced changes in the marine environment, probably related to increased pollution and eutrophication.

Concentrations of dinoflagellate cysts in the surface layer of bottom sediment from the White Sea

Dinoflagellate cysts were studied in 42 samples from surface sediments of the White Sea. Total concentration of dinocysts varies from single cysts to 25000 cyst/g of dry sediments, which reflects biological productivity in White Sea waters and regional particular features of sedimentation processes. The highest concentrations are observed in silts; they are related to the regions of propagation of highly productive Barents Sea waters in the White Sea. Generally, spatial distribution of dinocyst species in the surface sediments corresponds to distribution of the major types of water masses in the White Sea. Cysts of relatively warm-water species (Operculodinium centrocarpum, Spiniferites sp.) of North Atlantic origin that dominate in the sediments indicate an intensive intrusion of Barents Sea water masses to the White Sea along with hydrological dwelling conditions in the White Sea favorable for development of these species during their vegetation period. The cold-water dinocyst assemblage (Islandinium minutum, Polykrikos sp.) is rather strictly confined to inner parts of shallow-water bays, firstly, those adjacent to the Onega and Severnaya Dvina river mouths.

Plant communities and soil chemistry of shrub-steppe and pine savannah grasslands in southern British Columbia, Canada

Habitat fragmentation alters the edges of remnant habitat patches. We examined changes in the plant community and soil in relation to distance from edge and edge type for shrub-steppe and pine savannah grasslands in southern British Columbia, Canada. Community composition showed significant nonlinear relationships with distance-to-edge more frequently at paved roads and fruit crops than at dirt roads or control sites (i.e., in the interior of grassland patches), with changes typically extending 25-30 m. More exotic species and fewer native species were found near edges, and edges showed decreased cryptogam cover and increased bare ground, especially near paved roads. The soil factors that best predicted compositional changes were soil pH and Cu/Mn at paved roads, soil pH and nitrogen at fruit crops, and soil resistance at dirt roads. Variation partitioning suggested that both direct (e.g., propagule pressure) and indirect (environmental change) factors mediated edge-related community changes, and provided evidence that nonlinear responses at developed edges were not due to natural gradients. Given the range of grassland patch sizes in this region (many patches 1-100 ha), the edge effects we observed represent a considerable loss of "core" habitat, which must be accounted for in conservation planning and site restoration.

Individual dinoflagellate cysts species of surface sediment samples from the Mediterranean Sea

To determine the relationship between the spatial dinoflagellate cyst distribution and oceanic environmental conditions, 34 surface sediments from the Eastern and Western Mediterranean Sea have been investigated for their dinoflagellate cyst content. Multivariate ordination analyses identified sea-surface temperature, chlorophyll-a , nitrate concentration, salinity, and bottom oxygen concentration as the main factors affecting dinoflagellate cyst distribution in the region. Based on the relative abundance data, two associations can be distinguished that can be linked with major oceanographic settings. (1) An offshore eastern Mediterranean regime where surface sediments are characterized by oligotrophic, warm, saline surface water, and high oxygen bottom water concentrations (Impagidinium species, Nematosphaeropsis labyrinthus, Pyxidinopsis reticulata and Operculodinium israelianum). Based on the absolute abundance, temperature is positively related to the cyst accumulation of Operculodinium israelianum. Temperature does not form a causal factor influencing the accumulation rate of the other species in this association. Impagidinium species and Nematosphaeropsis labyrinthus show a positive relationship between cyst accumulation and nitrate availability in the upper waters. (2) Species of association 2 have highest relative abundances in the Western Mediterranean Sea, Strait of Sicily/NW Ionian Sea, and/or the distal ends of the Po/Nile/Rhône River plumes. At these stations, surface waters are characterized by (relative to the other regime) higher productivity associated with lower sea-surface temperature, salinity, and lower bottom water oxygen concentrations (Selenopemphix nephroides, Echinidinium spp., Selenopemphix quanta, Quinquecuspis concreta, Brigantedinium spp. and Lingulodinium machaerophorum). Based on both the absolute and relative abundances, Selenopemphix nephroides is suggested to be a suitable indicator to trace changes in the trophic state of the upper waters. The distribution of Lingulodinium machaerophorum is related to the presence of river-influenced surface waters, notably the Nile River. We suggest that this species might form a suitable marker to trace past variations in river discharge, notably from the Nile.