Halophyte plants are known for their resistance to harsh environmental conditions associated with excess salts in their habitats. Their resistance to salinization is due, among other things, to their high ability to detoxify free radicals, owing to the relatively high content of antioxidants. On the coast of the Baltic Sea and in the lagoons, there are several rare halophyte species included in the Red Book of the Kaliningrad Region (Russia) and the Baltic region, such as Spergularia marina (L.) Griseb. and Glaux maritima L. The aim of the research was to study the accumulation of certain groups of phenolic compounds in different parts of S. marina and G. maritima plants under conditions of weak and strong soil salinity, as well as to analyze the antioxidant, antibacterial, and fungicidal activity of extracts of the studied plant species. The present study showed an increase in total phenolic content in the roots and shoots of S. marina, and the shoots of G. maritima, in response to increased soil salinity. At the same time, the total content of flavonoids in all the studied parts of the two plant species remained unchanged. However, the content of individual flavonoids (hesperetin, epicatechin, apigenin derivative, luteolin derivative) in S. marina increased, for G. maritima there was a tendency to reduce the content of flavonoids in roots and shoots with an increase in soil salinity. There was an increase in the total content of hydroxycinnamic acids in the roots of Glaux maritima, as well as an increase in the content of protocatechuic acid in the roots and shoots of Spergularia marina. A positive relationship was established between the antioxidant activity of S. marina root extracts and the total content of phenolic compounds, as well as G. maritima shoots extracts and the total content of phenolic compounds. Extracts of S. marina showed no antibacterial activity against Escherichia coli and Bacillus subtilis, and weak fungicidal activity of stem extracts and inflorescences grown on soils, with high levels of salinities, was detected against Candida albicans. The extracts of roots and shoots from G. maritima showed weak antimicrobial and fungicidal activity.

Green alga Hydrodictyon reticulatum was found for the first time in the Curonian Lagoon in 1936, however, it was still absent in the species lists of the algal flora of the Russian part of the Curonian Lagoon up to date. H. reticulatum was found in shallow waters (0.6 m depth) of small bays in the southern (near village Kaširskoe) and south-western (Curonian spit, 1 km to the north of the Tëplyj Bay) coasts of the Curonian Lagoon in June- July 2011. Species was found on the petioles and twigs of submerged aquatic plants Nuphar lutea, Nymphaea candida and Ceratophyllum demersum.

Приведены сведения о первых находках Gaillona rosea (Roth) Athanasiadis 2016:814 (Aglaothamnion roseum (Roth) Maggs & L’Hardy-Halos 1933:522) в российской части Юго-Восточной Балтики. Пробы водорослей в российской части Юго-Восточной Балтики вдоль побережья Калининградской области на глубинах 1–15 м отбирали на северном побережье Самбийского полуострова в районе м. Таран и м. Гвардейский на станциях, приуроченных к твёрдым грунтам. Первые образцы талломов G. rosea осенью 2015 г. собраны в плавающих матах многолетних водорослей Furcellaria lumbricalis и Polysiphonia fucoides, обнаруженных вдоль западного и северного побережья Самбийского полуострова (м. Таран) на глубинах 1,5–7 м. Для побережья Гданьского залива (западный берег Самбийского полуострова) находки вида в 2015 г. ― это первая регистрация. В июле 2016 г. вид обнаружен в пробах на м. Таран на глубине 0,5 м. Размеры талломов не превышают 3 см. Вид встречается с F. lumbricalis и P. fucoides как в прикреплённых сообществах, так и в дрейфующих матах. В Балтийском море G. rosea довольно распространён, за исключением Гданьского залива и самой северной части Балтики, характеризующейся низкой солёностью. В сопредельных литовских водах данные об обилии вида отсутствуют. Учитывая, что находки вида редки и в российской части ЮВБ, можно заключить, что G. rosea редок во всей Юго-Восточной Балтике.