Spatiotemporal dataset on moon jellyfish incidental observations in the Gulf of Riga and Eastern Gotland Basin, Baltic Sea.

This data article describes the occurrences of the moon jelly medusae in the Gulf of Riga and Eastern Gotland Basin (Baltic Sea) between 1998 and 2023. All data are incidental observations obtained during Latvian national monitoring cruises. Gelatinous zooplankton is not a standard group in regional marine monitoring, and jellyfish are not intentionally monitored within the framework of national marine monitoring by many countries across the Baltic Sea region.

Feeding inhibition in daphnids - A sensitive and rapid toxicity endpoint for chemical stress?

The planktonic Crustacea are among the most employed organisms in ecotoxicology, mainly in regulatory assays that follow OECD/ISO protocols. The most common endpoint for acute testing (24-48 h) without feeding of organisms is usually monitored as mortality or immobilization. A rapid and physiologically and environmentally more relevant toxicity endpoint could be the impaired feeding of daphnids.

Snow dumping station - A considerable source of tyre wear, microplastics, and heavy metal pollution.

Snow dumping stations can be a hotspots for pollutants to water resources. However, little is known about the amount of microplastics including tyre wear particles transported this way. This study investigated microplastics and metals in snow from four snow dumping stations in Riga, Latvia, a remote site (Gauja National Park), and a roof top in Riga.

Downward migrating microplastics in lake sediments are a tricky indicator for the onset of the Anthropocene.

Plastics are a recent particulate material in Earth's history. Because of plastics persistence and wide-range presence, it has a great potential of being a global age marker and correlation tool between sedimentary profiles. In this research, we query whether microplastics can be considered among the array of proxies to delimit the Anthropocene Epoch (starting from the year 1950 and above).

A guide to the use of bioassays in exploration of natural resources.

Bioassays are the main tool to decipher bioactivities from natural resources thus their selection and quality are critical for optimal bioprospecting. They are used both in the early stages of compounds isolation/purification/identification, and in later stages to evaluate their safety and efficacy. In this review, we provide a comprehensive overview of the most common bioassays used in the discovery and development of new bioactive compounds with a focus on marine bioresources.

Acute toxicity of triclosan, caffeine, nanoplastics, microplastics, and their mixtures on Daphnia magna.

We measured acute toxicity of triclosan, caffeine, nanoplastics, and microplastics, and their mixtures on Daphnia magna. Limitations of this study included use of a single species, acute rather than chronic toxicity testing, examination of single substances and their mixtures, and laboratory conditions that may not reflect real-world scenarios. Single compound toxicity results revealed a clear concentration-response pattern, with triclosan showing higher toxicity than caffeine, and nanoplastics displaying higher toxicity than microplastics.

Assessing the Occurrence and Distribution of Microplastics in Surface Freshwater and Wastewaters of Latvia and Lithuania.

Microplastic concentrations in surface water and wastewater collected from Daugavpils and Liepaja cities in Latvia, as well as Klaipeda and Siauliai cities in Lithuania, were measured in July and December 2021. Using optical microscopy, polymer composition was characterized using micro-Raman spectroscopy. The average abundance of microplastics in surface water and wastewater samples was 16.

Dataset on microplastic concentrations, characteristics, and chemical composition in the marine surface waters of Latvia - the Eastern Gotland basin and the Gulf of Riga.

The dataset provides information on spectroscopically verified microplastics, both particles and fibers, from 44 marine surface water samples of two Baltic Sea sub-basins - the semi-enclosed Gulf of Riga and the Eastern Gotland Basin. Sampling was performed by using Manta trawl with a mesh size of 300 µm. Thereafter, the organic material was digested with sodium hydroxide, hydrogen peroxide and enzymes.

Seasonal dynamic of diazotrophic activity and environmental variables affecting it in the Gulf of Riga, Baltic Sea.

The semi-enclosed Baltic Sea experiences regular summer blooms of diazotrophic cyanobacteria. Previously, it has been conclusively demonstrated that in open nitrogen-limited parts of the Baltic Sea, cyanobacteria successfully fix atmospheric N2. At the same time, diazotrophic activity is still poorly understood in Baltic Sea sub-regions where nitrogen and phosphorus are co-limiting primary production.

Assessing the potential for sea-based macroalgae cultivation and its application for nutrient removal in the Baltic Sea.

Marine eutrophication is a pervasive and growing threat to global sustainability. Macroalgal cultivation is a promising circular economy solution to achieve nutrient reduction and food security. However, the location of production hotspots is not well known.

Hide-and-seek: Threshold values and contribution towards better understanding of recovery rate in microplastic research.

Microplastic pollution has become one of the most pressing environmental issues. A fundamental criterion for risk assessment is the concentration of found microplastic that can be altered during microplastic isolating from the sample. Recovery rate (i.

The role of marinas in the establishment and spread of non-indigenous species in Baltic Sea fouling communities.

The study included the sampling of 12 marinas across six areas of the Baltic Sea with settlement plates and scraping of submerged structures to assess the role of marinas in the spread of non-indigenous species (NIS) biofouling. 15 NIS were detected in the marinas and secondary spread of previously introduced NIS was detected in five out of six sea areas. Salinity and sea area significantly affected the composition of the fouling assemblages.

Occurrence and spatial distribution of microplastics in the surface waters of the Baltic Sea and the Gulf of Riga.

The study is comparing microplastic debris distribution and composition in the Gulf of Riga and the Eastern Gotland Basin, Baltic Sea. Samples from 44 stations were collected from coastal and open water sites using Manta trawl (mesh size 300 μm). The natural organic material was digested sequentially with sodium hydroxide, hydrogen peroxide and enzymes.

Assessing change in habitat composition, ecosystem functioning and service supply in Latvian protected stony reefs.

Healthy and diverse marine ecosystems are a source of a whole range of ecosystem services (ES) and social, and economic benefits. To preserve and restore biodiversity, and sustain service supply, an international goal was set to protect at least 10 % of the global coastal and marine area by 2020. The goal has been achieved mainly through the designation of marine protected areas (MPAs).

Disentangling temporal food web dynamics facilitates understanding of ecosystem functioning.

Studying how food web structure and function vary through time represents an opportunity to better comprehend and anticipate ecosystem changes. Yet, temporal studies of highly resolved food web structure are scarce. With few exceptions, most temporal food web studies are either too simplified, preventing a detailed assessment of structural properties or binary, missing the temporal dynamics of energy fluxes among species.

Environmental Impact of Geosynthetics in Coastal Protection.

Geosynthetic materials are applied in measures for coastal protection. Weathering or any damage of constructions, as shown by a field study in Kaliningrad Oblast (Russia), could lead to the littering of the beach or the sea (marine littering) and the discharge of possibly harmful additives into the marine environment. The ageing behavior of a widely used geotextile made of polypropylene was studied by artificial accelerated ageing in water-filled autoclaves at temperatures of 30 to 80 °C and pressures of 10 to 50 bar.

Correction to: Zooplankton indicator-based assessment in relation to site location and abiotic factors: a case study from the Gulf of Riga.

This paper, published in Environ Monit Assess 192, 147 (2020), contains errors in Table 5.

Development of fish age normalization technique for pollution assessment of marine ecosystem, based on concentrations of mercury, copper, and zinc in dorsal muscles of fish.

Correlation between metal concentrations in fish tissues and fish body size poses certain challenge when comparing concentration levels encountered at different locations or time periods by degrading performance of statistical tests due to variable age composition of fish sample pool. In order to overcome this, the concentrations of Hg, Cu, and Zn, measured in tissues of five fish species, were normalized to selected age group. Computed species-specific equations, based on empirically obtained exponential relationship, provided accurate estimates of the normalized concentrations under the conditions of substantial metal and fish age covariation.

Zooplankton indicator-based assessment in relation to site location and abiotic factors: a case study from the Gulf of Riga.

There are a number of zooplankton parameters proposed as indicators to evaluate environmental status of marine ecosystems. Mean size and total stock (MSTS) is the only zooplankton-based and HELCOM (Baltic Marine Environment Protection Commission - Helsinki Commission)-approved core indicator. MSTS was developed to evaluate the environmental status of the Baltic Sea based on total biomass (or abundance) and mean body weight of mesozooplankton.

Food web and fisheries in the future Baltic Sea.

We developed numerical simulations of potential future ecological states of the Baltic Sea ecosystem at the end of century under five scenarios. We used a spatial food web (Ecospace) model, forced by a physical-biogeochemical model. The scenarios are built on consistent storylines that describe plausible developments of climatic and socioeconomic factors in the Baltic Sea region.

Understanding the distribution of economic benefits from improving coastal and marine ecosystems.

The ecological status of coastal and marine waterbodies world-wide is threatened by multiple stressors, including nutrient inputs from various sources and increasing occurrences of invasive alien species. These stressors impact the environmental quality of the Baltic Sea. Each Baltic Sea country contributes to the stressors and, at the same time, is affected by their negative impacts on water quality.

An integrated assessment of pollution and biological effects in flounder, mussels and sediment in the southern Baltic Sea coastal area.

Organic and metal contaminants and biological effects were investigated in flounder, mussels, and sediments in the southern Baltic Sea coastal area in order to assess environmental quality status in that area. Four sites were selected, including two within the Gulf of Gdańsk (GoG). In biota and sediment at each site, DDTs dominated over PCBs and PBDEs were the least abundant among organic contaminants.

Indicator Properties of Baltic Zooplankton for Classification of Environmental Status within Marine Strategy Framework Directive.

The European Marine Strategy Framework Directive requires the EU Member States to estimate the level of anthropogenic impacts on their marine systems using 11 Descriptors. Assessing food web response to altered habitats is addressed by Descriptor 4 and its indicators, which are being developed for regional seas. However, the development of simple foodweb indicators able to assess the health of ecologically diverse, spatially variable and complex interactions is challenging.

Bioaccumulation of hepatotoxins - a considerable risk in the Latvian environment.

The Gulf of Riga, river Daugava and several interconnected lakes around the City of Riga, Latvia, form adynamic brackish-freshwater system favouring occurrence of toxic cyanobacteria. We examined bioaccumulation of microcystins and nodularin-R in aquatic organisms in Latvian lakes, the Gulf of Riga and west coast of open Baltic Sea in 2002-2007. The freshwater unionids accumulated toxins efficiently,followed by snails.