Use of Stress Signals of Their Attached Bacteria to Monitor Sympagic Algae Preservation in Canadian Arctic Sediments

Based on the strong aggregation of sympagic (ice-associated) algae and the high mortality or inactivity of bacteria attached to them, it was previously hypothesized that sympagic algae should be significant contributors to the export of carbon to Arctic sediments. In the present work, the lipid content of 30 sediment samples collected in the Canadian Arctic was investigated to test this hypothesis. The detection of high proportions of trans vaccenic fatty acid (resulting from cis-trans isomerase (CTI) activity of bacteria under hypersaline conditions) and 10S-hydroxyhexadec-8(trans)-enoic acid (resulting from 10S-DOX bacterial detoxification activity in the presence of deleterious free palmitoleic acid) confirmed: (i) the strong contribution of sympagic material to some Arctic sediments, and (ii) the impaired physiological status of its associated bacterial communities. Unlike terrestrial material, sympagic algae that had escaped zooplanktonic grazing appeared relatively preserved from biotic degradation in Arctic sediments. The expected reduction in sea ice cover resulting from global warming should cause a shift in the relative contributions of ice-associated vs. pelagic algae to the seafloor, and thus to a strong modification of the carbon cycle.

Dynamics of Plankton Community in Banahao-Palhi River in Leyte, Philippines

Plankton consists of microscopic plants “phytoplankton” and animals “zooplankton“. They play a principal role in aquatic food web and zooplankton indicators of ecosystem change. Phytoplankton are the food source for zooplankton, and together, form the base of ocean and river food chains. In Leyte, few researches have been conducted in plankton specifically in river systems. The study was conducted to understand phytoplankton dynamics by first studying their occurrence, composition, and abundance. Three sampling sites were established along Banahao-Palhi river during dry and wet seasons. A total of 162 plankter samples were analyzed in the laboratory. Dry season sampling showed 99 pelagic algae belonging to 58 genera across sites. In all sites, the commonly occurring diatoms were Biddulphia, Meridion, and Synedra . For the green algae (Chlorophyceae) group, Groenbladia was the most common genus, while in the blue-greens (Cyanophyceae), Nostoc. In wet season, 165 pelagics in 68 genera were observed. Bacillariophyceae got the most number of pelagic algae in all sites for both seasons. For true zooplankton, eight families were recorded during the dry season with four, belonging to Rotifera, two under Copepoda and one, from Cladocera. Similar groups were found during wet season. Larvae of insects and benthics were found part of the zooplankton community. Insect groups include Orders Coleoptera, Diptera, Ephemeroptera, Megaloptera, Plecoptera and Trichoptera. Non-insect groups include Arachnida, Amphipoda, Gastropoda and fish larvae. The Rotifera is the commonly occurring holoplankton with six genera identified. However, the copepods were the most abundant in Brgy. Palhi while protozoans, in Brgy. Banahao.