Chlorophyll a concentration in plankton, biomass of different taxonomic phytoplankton groups, dominating algae species, and some parameters of coastal surface waters of the Black Sea

Based on data obtained at three stations in coastal waters of the Black Sea off Sevastopol in 2000 and 2001, we present seasonal dynamics of the carbon to chlorophyll a ratio in nano- and microphy-toplankton. This parameter varied approximately tenfold throughout the year. Its maximum values (442-500) were obtained in summer (July), when Pyrrophyta dominated in phytoplankton. Minimum values (36-56) were observed in winter (December),when diatomaceous species predominated. We derive a regression relating the carbon to chlorophyll a ratio to proportion of Pyrrophyta in total phytoplankton biomass, doing so separately for warm and cold seasons. Regression equations demonstrate coupled action of irradiance, temperature, and nutrient availability on the carbon to chlorophyll a ratio. For Pyrrophyta phytoplankton assemblage R**2 = 0.95, and for diatomaceous one R**2 = 0.87.

The effect of a reduction of nitrogen and phosphorus to eutrophic and mesotrophic conditions towards silver nanoparticle (AgNP) on freshwater green algae species

We investigated the sensitivity of algae towards silver nanoparticles with OECD test medium and lower nutrient concentrations under standard test conditions to improve comparability and to exclude any other confounding factor aside nutrient levels. Two unicellular freshwater microalgae Desmodesmus subspicatus and Raphidocelis subcapitata were chosen due to their status as standard test organisms for the algae growth inhibition test and the response to changes in nutrient supply was compared. The original medium was used as the reference (standard). For the other four media, the amount of either nitrogen or phosphorus in the medium was lowered from half (50%) to one-fourth (25 %) of that of the OECD guideline, resulting in the following media: 50% N, 25% N, 50% P and 25% P medium. As test substance, the OECD reference material NM-300K was used. For this reason, the characterization of AgNP was done using DLS and Absorption spectra (UV/vis). Actual silver concentrations and ionic silver concentrations were measured at the highest test concentration used (100 µg Ag L-1) in R. subcapitata treatments only to reduce the number of samples. All tests were run according to the OECD guideline 201 with sterilized 50 mL cell culture flask. Each medium was tested using the test conditions for culturing with 3 replicates. Test concentrations for both algae species were 0, 25, 50 and 100 µg Ag L-1 for OECD, 50% P and 25% P while for both N reductions, the silver concentrations were 0, 10, 25 and 100 µg Ag L-1. Samples for determining the algal density were taken at every 24 h.

Crustaceans and fish abundances and species at and around artificially introduced tetrapod fields in the southern North Sea, 2009

The micro-scale spatial distribution patterns of a demersal fish and decapod crustacean assemblage were assessed in a hard-bottom kelp environment in the southern North Sea. Using quadrats along line transects, we assessed the in situ fish and crustacean abundance in relation to substratum types (rock, cobbles and large pebbles) and the density of algae. Six fish and four crustacean species were abundant, with Ctenolabrus rupestris clearly dominating the fish community and Galathea squamifera dominating the crustacean community. Differences in the substratum types had an even stronger effect on the micro-scale distribution than the density of the dominating algae species. Kelp had a negative effect on the fish abundances, with significantly lower average densities in kelp beds compared with adjacent open areas. Averaged over all of the substrata, the most attractive substratum for the fish was large pebbles. In contrast, crustaceans did not show a specific substratum affinity. The results clearly indicate that, similar to other complex systems, significant micro-scale species-habitat associations occur in northern hard-bottom environments. However, because of the frequently harsh environmental conditions, these habitats are mainly sampled from ships with sampling gear, and the resulting data cannot be used to resolve small-scale species-habitat associations. A detailed substratum classification and community assessment, often only possible using SCUBA diving, is therefore important to reach a better understanding of the functional relationships between species and their environment in northern temperate waters, knowledge that is very important with respect to the increasing environmental pressure caused by global climate change.

Phytoplankton in the surface desalted lens of the Kara Sea

Phytoplankton of a surface strongly desalinated water lens was investigated on the basis of materials collected during Cruise 57 of R/V Akademik Mstislav Keldysh in September 2007. The lens with salinity <18 psu had area of ca. 19000 sq. km and was located in the northwestern part of the Kara Sea near the eastern coast of Novaya Zemlya. It was a specific biotope that had been isolated from surrounding waters for more than three months. In the investigated area 66 algae species were identified. The maximal species diversity was found in the upper layers of the desalinated lens, where species number was 1.5 to 3 times higher than in other parts of the water column. Phytoplankton abundance in the upper layers of the lens was 1.5 to 4.5 times higher than in its lower part and generally higher than below the picnocline. Diatoms were the most abundant group in the upper layers of the lens, while flagellates dominated in the subpicnocline part of the water column. Maximal values of phytoplankton biomass were observed everywhere in the upper layers of the lens, where they were 1.2 to 3.7 times higher than in the lower part of the lens and 1.3 to 7.2 times higher than in the layer below the picnocline. Dinoflagellates generally gave the most contribution to total phytoplankton biomass. Phytoplankton of the desalinated surface lens in the northwestern part of the Kara Sea by its composition and quantitative parameters had the nearest resemblance to a phytocenosis that we observed two weeks later at a shallow desalinated shelf closely adjacent to the Ob estuary.

Pigments, phytoplankton and its production parameters in the Obskaya Guba and adjacent Kara Sea in the latest September 2007

Material was collected in the Ob River estuary and the adjacent shallow Kara Sea shelf between 71°14.0'N and 75°33.0'N at the end of September 2007. Latitudinal zonation in phytoplankton distribution was demonstrated; this zonation was determined by changes in salinity and concentration of nutrients. Characteristic of the phytocenosis in the southern desalinated zone composed of freshwater diatom and green algae species were high population density (1500000 cells/l), biomass (210 ?g C/l), chlorophyll concentration (4.5 ?g/l), and uniform distribution in the water column. High primary production (~40 ?g C/l/day) was recorded in the upper 1.5 m layer. The estuarine frontal zone located to the north had a halocline at depth 3-5 m. Freshwater species with low abundance (250000 cells/l), biomass (24 ?g C/l), and chlorophyll concentration (1.5 ?g/l) dominated above the halocline. Marine diatom algae, dinoflagellates, and autotrophic flagellates formed a considerable part of the phytocenosis below the halocline; community characteristics were two-fold lower as compared with the upper layer. Maximal values of primary production (~10 ?g C/l/day) were recorded in the upper 1.5 m layer. The phytocenosis in the seaward zone was formed by marine alga species and was considerably poorer as compared with the frontal zone. Assimilation rates of carbon per chlorophyll a at the end of the vegetation season within the studied area were low, average 0.4-1.0 ?g C/?g Chl/hour in the upper layer and 0.03-0.1 ?g C/?g Chl/hour below the pycnocline.

Phytoplankton biomass, chlorophyll concentration, and variability of lipid content in Calanus euxinus in the Black Sea in June 1991

During field studies relationships between chlorophyll concentrations, phytoplankton biomass (total, individual sizes and species) and level of accumulation of total lipids, wax esters, triacylglycerols, and phospholipids in C. euxinus (copepodites V and females) were studied. These relationships allowed to display not only simple trophic relations between isolated parts of the C. euxinus population and phytoplankton, but also selective role of individual algae species in forming lipid reserves too. Besides it was found that geographical variability of chlorophyll concentration and phytoplankton biomass correlates closely only with those lipid fractions (wax esters and phospholipids) of C. euxinus, which accumulated and kept in a body for a fairly long time. No correlation was found between phytoplankton and for rapidly metabolized triacylglycerols, which have to be utilized within few hours.

Fast coral reef calcifiers are more sensitive to ocean acidification in short-term laboratory incubations

To identify the properties of taxa sensitive and resistant to ocean acidification (OA), we tested the hypothesis that coral reef calcifiers differ in their sensitivity to OA as predictable outcomes of functional group alliances determined by conspicuous traits. We contrasted functional groups of eight corals and eight calcifying algae defined by morphology in corals and algae, skeletal structure in corals, spatial location of calcification in algae, and growth rate in corals and algae. The responses of calcification to OA were unrelated to morphology and skeletal structure in corals; they were, however, affected by growth rate in corals and algae (fast calcifiers were more sensitive than slow calcifiers), and by the site of calcification and morphology in algae. Species assemblages characterized by fast growth, and for algae, also cell-wall calcification, are likely to be ecological losers in the future ocean. This shift in relative success will affect the relative and absolute species abundances as well as the goods and services provided by coral reefs.