Characterization of the particulate protein in Pacific surface waters

The molecular characteristics of particulate protein in the surface waters along transects from 45N to 25S in the central Pacific are reported. The majority of particulate-combined amino acids (PCAA) was in the form of protein molecules in the samples from the northern North Pacific and Equatorial regions, namely, productive areas, while PCAA was mainly present as nonproteinaceous amino acid in the subtropical regions, namely, oligotrophic areas. Thus, it appears that the chemical form of PCAA, one of the major constituents of particulate organic matter (POM), varies meridionally. Two characteristic groups of particulate protein were identified from meridional differences in their molecular distribution. The first group, derived directly from cellular proteins of living organisms, was made up of a large number of proteins, each present at a relatively low level, which gave smeared electrophoretograms and were considered to be “background” proteins. The background proteins contributed greatly to the total protein, as well as to PCAA, and they appeared to be readily remineralized. The second group included a small number of specific proteins with a limited range of molecular masses. This group was prevalent in oligotrophic areas, an indication that proteins from specific sources survive and accumulate as a consequence of their resistance to degradation. A protein with an apparent molecular mass of 45 kilodaltons (kDa), a member of the second group, was commonly found at low latitudes and the partial N-terminal amino acid sequence indicated that the 45-kDa protein was a single protein species that has not previously been reported. Thus, a single and identifiable protein molecule appears to be very widespread at low latitudes

Reviews and Syntheses: Ocean acidification and its potential impacts on marine ecosystems

Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO₂ that adds up with dissolved inorganic carbon (dissolved CO₂, H₂CO₃, HCO₃⁻, and CO₃²⁻) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO₂ itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different timescales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena

Choanoflagellates in the Antarctic Ocean, with special reference to Parvicorbicula socialis (Meunier) Deflandre

Distribution and morphology of choanoflagellates, collared heterotrophic flagellates bearing an extracellular siliceous lorica, were reviewed. Eleven species were reported from the Antarctic Ocean. Three of the eleven species were originally described from the Antarctic and are known to be endemic to the Antarctic. The other eight were found in various oceanic areas. Choanoflagellates had been found in both ice and water, which suggested their wide and abundant distribution in the Antarctic. Ecological significance of the choanoflagellate, Parvicorbicula socialis (MEUNIER) DEFLANDRE, most common species in the Antarctic, was stressed as the food of the Antarctic krill, Euphausia superba DANA. Morphological variation of the lorica structure of P. socialis, caused by water temperature, was discussed on specimens collected in various oceanic areas from polar to equatorial

Organic compounds of the suspended particles in the Pacific Sector of the Southern Ocean

Particulate matter was collected from the ocean areas of the West Pacific and the Pacific Sector of the Antarctic Ocean (32°N-65°S, 125°-160°E) during the cruise of T. S. UMITAKA MARU of Tokyo University of Fisheries in 1980-1981. The samples were analyzed for organic carbon and nitrogen, carbohydrate, amino acids including free and combined forms, lipid and chlorophylls. Detailed analyses of fatty acids of the particulate samples were conducted to clarify their ecological significance in the Antarctic Ocean. Characteristic features of particulate organic matter in the Antarctic Ocean are as follows. 1) Particulate organic carbon (POC) and nitrogen (PON) collected from the surface waters of the western Pacific and Antarctic Oceans were determined as the ranges of 25.4-150μgC/l and 3.50-25.2μgC/l respectively. POC and PON are distributed with relatively low values in the western Pacific Ocean, while much higher level of the values was observed in the Antarctic Ocean. Regional variabilities of the values occurred to a great extent. 2) Particulate matter collected from the Antarctic Ocean was analyzed for carbohydrate, amino acid and lipid, which accounted for 18.6-40.3%, 11.1-16.5% and 22.7-37.8% of POC respectively. Lipid materials were much abundant in the particulate matter collected from the oceanic area south of the Antarctic Divergence. 3) Fatty acids with carbon atoms ranging from 14 to 24 were detected in the particulate matter from the Antarctic Ocean and were quantified by gas chromatography. The ratio of unsaturated fatty acids with carbon atoms of 16,18 and 20 to total fatty acids tended to increase toward Antarctica. These unsaturated fatty acids accounted for more than 40% of total fatty acids of the particulate matter from the oceanic area south of the Antarctic Divergence. 4) Fecal pellet of Euphausia superba and its feed, Dunaliella tertiolecta were analyzed for fatty acids to elucidate their ecological significance in the Antarctic Ocean. The results obtained indicated that algal fatty acids and amino acids were digested exclusively by the zooplankton. Unsaturated fatty acids with carbon atoms of 16 and 18 accounted for more than 80% of total loss of the fatty acids during the digestion processes of algal organic matter by the zooplankton. These findings strongly suggested that unsaturated fatty acids must be one of the most ecologically significant organic materials in the Antarctic Ocean