Home About us Contact
|
Home About us Contact | ||
|
|
||
Coastal Marine Environment (coastal + marine_environment)
Selected AbstractsTHE TYCHOPELAGIC DIATOM, PARALIA SULCATA, AS PALEOINDICATOR SPECIES IN COASTAL MARINE ENVIRONMENTSJOURNAL OF PHYCOLOGY, Issue 2000M.R. McQuoid Paralia sulcata is a diatom commonly found in both the plankton and benthos of coastal environments. This species is heavily silicified and, thus preserves well in sedimentary records making it a potentially useful paleoindicator species. However, its tychopelagic nature and its association with a wide range of environmental conditions have made detailed paleoecological interpretations complicated. High-resolution sediment records from coastal fjords in both Canada and Sweden show variations in the abundance and morphology of P. sulcata that provide evidence of changes in benthic habitat distribution and surface water properties in the fjords on timescales of decades to centuries. These studies suggest that P. sulcata can be an important paleoindicator species when interpretations are made in the context of its complex ecology. [source] Spatial correlation patterns in coastal environmental variables and survival rates of salmon in the north-east Pacific OceanFISHERIES OCEANOGRAPHY, Issue 4 2002Franz J. Mueter We examined spatial correlations for three coastal variables [upwelling index, sea surface temperature (SST), and sea surface salinity (SSS)] that might affect juvenile salmon (Oncorhynchus spp.) during their early marine life. Observed correlation patterns in environmental variables were compared with those in survival rates of pink (O. gorbuscha), chum (O. keta), and sockeye (O. nerka) salmon stocks to help identify appropriate variables to include in models of salmon productivity. Both the upwelling index and coastal SST were characterized by strong positive correlations at short distances, which declined slowly with distance in the winter months, but much more rapidly in the summer. The SSS had much weaker and more variable correlations at all distances throughout the year. The distance at which stations were no longer correlated (spatial decorrelation scale) was largest for the upwelling index (> 1000 km), intermediate for SST (400,800 km in summer), and shortest for SSS (< 400 km). Survival rate indices of salmon showed moderate positive correlations among adjacent stocks that decreased to zero at larger distances. Spatial decorrelation scales ranged from approximately 500 km for sockeye salmon to approximately 1000 km for chum salmon. We conclude that variability in the coastal marine environment during summer, as well as variability in salmon survival rates, are dominated by regional scale variability of several hundred to 1000 km. The correlation scale for SST in the summer most closely matched the observed correlation scales for survival rates of salmon, suggesting that regional-scale variations in coastal SST can help explain the observed regional-scale covariation in survival rates among salmon stocks. [source] INTRACELLULAR CYANOBACTERIAL SYMBIONTS IN THE MARINE DIATOM CLIMACODIUM FRAUENFELDIANUM (BACILLARIOPHYCEAE)JOURNAL OF PHYCOLOGY, Issue 3 2000Edward J. Carpenter The diatom Climacodium frauenfeldianum Grunow was collected in the tropical Atlantic and Pacific Oceans. Observations with epifluorescence microscopy revealed that this diatom contained coccoid symbionts (2.5,3.5 ,m) with a typical cyanobacterial fluorescence in addition to that of their own chloroplasts. Mean concentration of C. frauenfeldianum for 28 stations in the SW tropical Pacific Ocean was 530 x 103 (SE = 1372) cells·m,2, with highest concentration (mean 17.5 cells·L,1) at 40-m depth. The symbiosis was only observed at water temperatures between 26.3 and 28.9° C, with highest concentrations at 27.7° C. Three almost complete 16S rDNA sequences from one sample were determined, and they were identical. The phylogenetic analysis of this 16S rDNA sequence and those from other cyanobacteria and plastids revealed that it was closely related to the 16S rDNA sequence from Cyanothece sp. ATCC 51142. Cyanothece sp. ATCC 51142 is a unicellular nitrogen-fixing cyanobacterium isolated from a coastal marine environment and has ultrastructural features similar to the symbionts of C. frauenfeldianum. The close relationship between Cyanothece sp. and the cyanobacterial symbiont in C. frauenfeldianum suggests the potential for nitrogen fixation in the symbiosis. [source] Space,time patterns of co-variation of biodiversity and primary production in phytoplankton guilds of coastal marine environmentsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2003Maria Rosaria Vadrucci Abstract 1.The relevance of biodiversity to ecosystem processes is a major topic in ecology. Here, we analyse the relationship between biodiversity and productivity of the nano- and micro-phytoplankton guilds in coastal marine ecosystems. 2.The patterns of variation of species richness, diversity and primary productivity (as 14C assimilation) were studied in two marine areas: a eutrophic,mesotrophic area beside the River Po delta (northern Adriatic) and an oligotrophic area around the Salento peninsula (southern Adriatic,Ionian). The study was carried out at 23 sites in the northern area and at 45 sites in the southern area. Sites were arranged on expected spatial and temporal gradients of primary productivity variation, according to distance from the coast, optical depths and seasonal period. 3.167 taxa were identified in the northern area and 153 taxa in the southern area. In both areas, the taxonomic composition of the nano- and micro-phytoplankton guilds exhibited greater temporal than spatial variation. The latter was much higher in the southern area than in the northern area (average dissimilarity between stations being 70.7±0.8% and 44.7±4.2% respectively). 4.Primary productivity varied in space and time on the gradients considered. Phytoplankton species richness and diversity exhibited significant patterns of variation in space and time; overall, these were inversely related to the primary productivity patterns in the northern area, whereas they were directly related in the southern area. 5.The small individual size and the high turnover rate of phytoplankton are likely to underlie the observed relationships, which emphasized a threshold response to nutrient enrichment in agreement with the ,paradox of enrichment'. Under resource enrichment conditions, the high turnover of producers leads to hierarchical partitioning of the available resources with an increasing dominance of a few species. Therefore, the relationship observed here seems likely to be explained by the complementarity hypothesis. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||