The Interplay of Mycosporine-like Amino Acids between Phytoplankton Groups and Northern Krill ( sp.) in a High-Latitude Fjord (Kongsfjorden, Svalbard).

We investigated pigment and mycosporine-like amino acid (MAA) concentrations of phytoplankton and Northern krill ( sp.) in sub-Arctic Kongsfjorden. Chlorophyll a (Chl-a) concentrations in the surface and middle-layer water were 0.

Type II photosensitized oxidation in senescent microalgal cells at different latitudes: Does low under-ice irradiance in polar regions enhance efficiency?

Comparison of Type II photosensitized oxidation of lipids (the photodynamic effect) and photodegradation of chlorophyll (sensitizer photobleaching) in samples of particulate matter collected previously from locations representing a diverse range of latitudes reveals an enhancement of the photooxidation of lipids at the expense of chlorophyll photodegradation in the polar regions. The efficiency of the photodynamic effect appears to be particularly high in sinking particles collected under sea ice and is attributed to the rapid settling of highly aggregated sympagic algae to depths of low light transmission favouring the photodynamic effect at the expense of photobleaching of the sensitizer. Paradoxically, the low efficiency of Type II photosensitized oxidation of lipids observed in temperate and equatorial regions is associated with high solar irradiances in these regions.

Evaluating bloom potential of the green-tide forming alga Ulva ohnoi under ocean acidification and warming.

The occurrence of green-tides, whose bloom potential may be increased by various human activities and biogeochemical process, results in enormous economic losses and ecosystem collapse. In this study, we investigated the ecophysiology of the subtropical green-tide forming alga, Ulva ohnoi complex (hereafter: U. ohnoi), under simulated future ocean conditions in order to predict its bloom potential using photosynthesis and growth measurements, and stable isotope analyses.

Synthesis of mycosporine-like amino acids by a size-fractionated marine phytoplankton community of the arctic beaufort sea.

During the RV-ARAON cruise, a comparative study on the biosynthesis of mycosporine-like amino acids (MAAs) was conducted for the size-fractionated phytoplankton of the Beaufort Sea (Arctic). The MAAs contents in the micro-phytoplankton community (>20 μm size) is considerably higher than that observed in the nano- (20-2 μm size) and pico-phytoplankton (<2 μm size) communities. The micro-phytoplankton of the Mackenzie Shelf had a relatively higher Chlorophyll a (Chl a) concentration.

Biodegradability of algal-derived organic matter in a large artificial lake by using stable isotope tracers.

In order to understand the biodegradability of algal-derived organic matter, biodegradation experiments were conducted with (13)C and (15)N-labeled natural phytoplankton and periphytic algal populations in experimental conditions for 60 days. Qualitative changes in the dissolved organic matter were also determined using parallel factor analysis and the stable carbon isotopic composition of the hydrophobic dissolved organic matter through the experimental period. Although algal-derived organic matter is considered to be easily biodegradable, the initial amounts of total organic carbon newly produced by phytoplankton and periphytic algae remained approximately 16 and 44 % after 60 days, respectively, and about 22 and 43 % of newly produced particulate nitrogen remained.

Production rate estimation of mycosporine-like amino acids in two Arctic melt ponds by stable isotope probing with NAH(13) CO3.

The net carbon uptake rate and net production rate of mycosporine-like amino acids (MAAs) were measured in phytoplankton from 2 different melt ponds (MPs; closed and open type pond) in the western Arctic Ocean using a (13) C stable isotope tracer technique. The Research Vessel Araon visited ice-covered western-central basins situated at 82°N and 173°E in the summer of 2012, when Arctic sea ice declined to a record minimum. The average net carbon uptake rate of the phytoplankton in polycarbonate (PC) bottles in the closed MP was 3.