Marine macrophytes retain microplastics

<p>Plastic contamination of marine beaches, sediments, water is widely reported. It is known that lot of plastic debris appears on marine shores after storms together with natural marine litter, like ragged vegetation, pieces of wood, etc. The goal of our field campaign in the southeastern part of the Baltic Sea was to check whether growing macrophytes also concentrate and retain plastics, particularly that of microplastic (MP, 0.2-5 mm here) size range. Three summer expeditions were conducted (July 30, August 5 and 7, 2019) in sea coastal zone (depth down to 10 m), where communities of attached macroalgae (<em>Furcellaria lumbricalis, Coccotylus truncatus, Polysiphonia fucoides, Cladophora rupestris</em>) are developed on underwater boulders off the Cape Taran. Samples were collected at 8 stations, covering areas with filamentous algae (at depths of 3.2 and 4 m) and with perennial algae furcellaria (depths of 5.6 and 8.2 m). Along with sampling of growing algae (from area 25x25 cm2 in triplicate), a hand pump was used to sample 20-100 liters of sea water from both algae thicket and algae-free water in surrounding area.</p><p>The samples were processed and examined in laboratory. Microplastic particles were found in all the collected samples. Preliminary analysis shows 1.3-5.3 times higher microplastic contamination in water samples taken from algae thicket than in samples taken in free water nearby. The majority of microparticles are fibers, mainly colorless and blue, but also red, black, golden, and yellow.</p><p>Investigations are supported by the Russian Science Foundation, grant No. 19-17-00041.</p>

Species composition and structure of macrophytobenthos in the lower part of the photic zone of the Kolvitsa inlet (Kandalaksha Bay, White Sea)

The Kolvitsa inlet of the Kandalaksha Bay is a poorly studied part of the White Sea. Sampling was carried out in intertidal and subtidal (using diving equipment) zones from 15 to 21 July 2016. Fifty species of macroalgae were found: 9 species of Chlorophyta, 18 species of Phaeophyceae, and 23 species of Rhodophyta. First records of Choreocolax polysiphoniae and Coccotylus hartzii in the Kandalaksha Bay are reported. The red algal zone at the Kolvitsa inlet extends at the depths from 7 to 17–18 m. Zonation and phytocoenoses with high species richness at the red algal belt were discovered. Community of Odonthalia dentata inhabits the depth of 7–8 m and includes 31 species of seaweeds with their average biomass 282.1 ± 37.6 g/m2; the height of vegetation is 20 cm; Coccotylus truncatus and Polysiphonia stricta are subdominants. Community of C. truncatus inhabits the depths from 8–9 to 11–12 m and includes 35 species of seaweeds with their average biomass 157.4 ± 92.2 g/m2; the height of vegetation is 10 cm; P. stricta, O. dentata and Phycodrys rubens are subdominants. Community of C. truncatus and P. rubens inhabits the depths from 11–12 to 14–15 m and includes 26 species of seaweeds with their average biomass 41.9 ± 1.1 g/m2; the height of vegetation is 5–6 cm; Euthora cristata is a subdominant. Few species of red cortical calcareous algae inhabit the depths from 15 to 18 m. Thirty two epiphytic algae were found. Secondary holdfasts on the erect filaments of Polysiphonia stricta were detected as a specific adaptation for attachment to basiphytes. Most of the epiphytes grow on three species mainly. C. truncatus may be considered as consorcium forming inside the phytocoenoses of the lower part of the photic zone because the biomass of its epiphytes is comparable with that of seaweeds on the ground in the same community.