Two real-time PCR assays targeting the small-subunit (SSU) ribosomal DNA (rDNA) were designed to assess the proportional biomass of diatoms and dinoflagellates in marine coastal water. The reverse primer for the diatom assay was designed to be class specific, and the dinoflagellate-specific reverse primer was obtained from the literature. For both targets, we used universal eukaryotic SSU rDNA forward primers. Specificity was confirmed by using a BLAST search and by amplification of cultures of various phytoplankton taxa. Reaction conditions were optimized for each primer set with linearized plasmids from cloned SSU rDNA fragments. The number of SSU rDNA copies per cell was estimated for six species of diatoms and nine species of dinoflagellates; these were significantly correlated to the biovolumes of the cells. Nineteen field samples were collected along the Swedish west coast and subjected to the two real-time PCR assays. The linear regression of the proportion of SSU rDNA copies of dinoflagellate and diatom origin versus the proportion of dinoflagellate and diatom biovolumes or biomass per liter was significant. For diatoms, linear regression of the number of SSU rDNA copies versus biovolume or biomass per liter was significant, but no such significant correlation was detected in the field samples for dinoflagellates. The method described will be useful for estimating the proportion of dinoflagellate versus diatom biovolume or biomass and the absolute diatom biovolume or biomass in various aquatic disciplines.Several diverse taxa are represented in the phytoplankton communities of coastal marine environments. These contribute to primary production and form the base of the marine food chain. Annual variation in primary production is caused by external factors such as nutrient access, light, and temperature (18). Seasonal patterns-including changes in phytoplankton diversity, community composition, and biovolumesalso affect the magnitude of primary production. Additionally, short-term fluctuations within the phytoplankton community are common and are due to the dynamics of local hydrographic conditions (1), zooplankton grazing (48), and exchange between sediment and the water column (6, 27). Thus, the structure of the phytoplankton community is influenced by several biotic and abiotic factors, and the taxonomic composition will, in turn, affect other functions of the marine ecosystem.Two of the most prominent and important phytoplankton classes in coastal marine waters and freshwater bodies are diatoms, Bacillariophyceae, and dinoflagellates, Dinophyceae. The taxonomic class Bacillariophyceae comprises approximately 100,000 extant species; planktonic species are predominantly autotrophic, and cell sizes range from 2 m to 5 mm (37). The number of dinoflagellate species in the marine phytoplankton is approximately 2,000, of which 50% are heterotrophic and the rest are auto-or mixotrophic. Their cell sizes range from 2 m to 2 mm (45). The variability within these classes is vast in many respects, but genetic, phy...

Vibrio abundance generally displays seasonal patterns. In temperate coastal areas, temperature and salinity influence Vibrio growth, whereas in tropical areas this pattern is not obvious. The present study assessed the dynamics of Vibrio in the Arabian Sea, 1-2 km off Mangalore on the south-west coast of India, during temporally separated periods. The two sampling periods were signified by oligotrophic conditions, and stable temperatures and salinity. Vibrio abundance was estimated by culture-independent techniques in relation to phytoplankton community composition and environmental variables. The results showed that the Vibrio density during December 2007 was 10- to 100-fold higher compared with the February-March 2008 period. High Vibrio abundance in December coincided with a diatom-dominated phytoplankton assemblage. A partial least squares (PLS) regression model indicated that diatom biomass was the primary predictor variable. Low nutrient levels suggested high water column turnover rate, which bacteria compensated for by using organic molecules leaking from phytoplankton. The abundance of potential Vibrio predators was low during both sampling periods; therefore it is suggested that resource supply from primary producers is more important than top-down control by predators.

Water samples and plankton net hauls were collected 24 times from Gullmar Fjord on the Swedish west coast from February 2004 to March 2005. The abundance of Skeletonema marinoi was estimated and individual clones isolated. Abundance was highest during the spring blooms in February to March. Subsequently, S. marinoi was detected in all samples but at lower abundances. At the end of September a second peak was recorded. All clones were pre-adapted to the same culturing conditions for more than 1.5 years. Large subunit (LSU) rDNA (D1-D3) was sequenced from 23 clones isolated from three different seasons, February, June and September. Six microsatellite loci were genotyped for 19 clones to estimate within-season genetic diversity. Three clones from each season were selected for physiological experiments at different salinity and temperature combinations and monitored for average number of divisions per day, maximum cell densities, biovolume, and total RNA concentration per cell. Differentiation of physiological response among the clones was partly attributed to the month of isolation. The February isolates had a significantly higher division rate and larger biovolumes, while the September clones attained higher cell densities. The June clones were isolated during the time of the year when the natural abundance is lowest, and exhibited the smallest genetic and physiological variation, which suggests that they were under strong selection pressure. The differential physiological responses and degree of genetic heterogeneity among seasonally separated clones could indicate that different populations succeed each other in the fjord.

This article documents the addition of 512 microsatellite marker loci and nine pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Alcippe morrisonia morrisonia, Bashania fangiana, Bashania fargesii, Chaetodon vagabundus, Colletes floralis, Coluber constrictor flaviventris, Coptotermes gestroi, Crotophaga major, Cyprinella lutrensis, Danaus plexippus, Fagus grandifolia, Falco tinnunculus, Fletcherimyia fletcheri, Hydrilla verticillata, Laterallus jamaicensis coturniculus, Leavenworthia alabamica, Marmosops incanus, Miichthys miiuy, Nasua nasua, Noturus exilis, Odontesthes bonariensis, Quadrula fragosa, Pinctada maxima, Pseudaletia separata, Pseudoperonospora cubensis, Podocarpus elatus, Portunus trituberculatus, Rhagoletis cerasi, Rhinella schneideri, Sarracenia alata, Skeletonema marinoi, Sminthurus viridis, Syngnathus abaster, Uroteuthis (Photololigo) chinensis, Verticillium dahliae, Wasmannia auropunctata, and Zygochlamys patagonica. These loci were cross-tested on the following species: Chaetodon baronessa, Falco columbarius, Falco eleonorae, Falco naumanni, Falco peregrinus, Falco subbuteo, Didelphis aurita, Gracilinanus microtarsus, Marmosops paulensis, Monodelphis Americana, Odontesthes hatcheri, Podocarpus grayi, Podocarpus lawrencei, Podocarpus smithii, Portunus pelagicus, Syngnathus acus, Syngnathus typhle,Uroteuthis (Photololigo) edulis, Uroteuthis (Photololigo) duvauceli and Verticillium albo-atrum. This article also documents the addition of nine sequencing primer pairs and sixteen allele specific primers or probes for Oncorhynchus mykiss and Oncorhynchus tshawytscha; these primers and assays were cross-tested in both species.

No abstract