In the current economic conditions, an active search is conducted for cost-effective and well-balanced feeds and feed mixtures for fish farming. The development of functional feeds using biomass of wild algae is becoming a central focus in the fish feed production. Although these supplements offer a promising path to sustainable and environmentally friendly fish feeding, their impact on the ecosystem requires detailed research. The aim of the study was to determine the acute response of Daphnia magna to the influence of new feed products derived from the wild algae of the Baltic Sea, phycocyanin on its own, and their binary mixture. The study was conducted using the standard aquatic toxicology method. To establish the 48-hour LC50, the probit analysis method was used. The results showed that D. magna is more sensitive to the effects of phycocyanin, with the following order of toxicity: phycocyanin > the mixture (1:1) > the biomass of Cladophora sp. The median lethal concentrations at 48 h were 100 mg/l, 920 mg/l, and 1720 mg/l, respectively. The obtained data allows to refer the tested compounds to low-hazard substances according to the Globally Harmonized System (GHS). The observed effects were compared with the effects of the mixture noticed in the toxic units (TU) model. In 48 hours, the mixture of the dry biomass of
Cladophora sp. and phycocyanin at a ratio of 1:1 exhibited synergism. The obtained results will allow choosing the optimal ratio of the raw materials used in fish feeds without inflicting harm to the aquatic ecosystem and loss of their nutritional value.
The SARS-CoV-2 pandemic affected the entire world and contributed to severe health and economic consequences. A safe and effective vaccine is a tool allowing the pandemic to be controlled. Hence, we aimed to conduct a survey on vaccinations against seasonal influenza and COVID-19 in Poland, Lithuania, and Ukraine. We also evaluated societal attitudes towards influenza and COVID-19 vaccinations. Materials and methods: We conducted the study between December 2020 and May 2021. At the time, the countries subject to the research were between the second and third waves of the COVID-19 pandemic. We used an anonymous and self-designed questionnaire comprised of eleven closed-ended questions and a short socio-demographic section. The questionnaire was administered by direct contact or mainly (due to the COVID-19 pandemic) by e-mail or Facebook. Finally, we included 2753 answers from Poland, 1852 from Ukraine, and 213 from Lithuania. Results: Between 61% (Poland) and 72.9% (Ukraine) of the study participants have never been vaccinated against influenza (p < 0.05). Totals of 67.6% of the respondents in Poland, 73.71% in Lithuania, and 29.5% in Ukraine responded that they want to be vaccinated against COVID-19 (p < 0.05). Vaccine hesitancy was mainly related to worries about its side effects. There were also vaccine non-adopters in the study. In Ukraine, 67% of the respondents were clearly opposed to mandatory COVID-19 vaccines, compared to 41.7% in Poland and 30.99% in Lithuania (p < 0.05). Conclusions: There are still many people who present vaccine hesitancy or are opposed to vaccines. Thus, societal education about vaccination and the pandemic is crucial. Vaccine hesitancy or refusal might be related to vaccine origin. Shortages of influenza vaccines made it impossible to vaccinate those who were determined to be vaccinated. There is room for discussion of mandatory COVID-19 vaccinations.