Darius Daunys

Recommendations on methods for the detection and control of biological pollution in marine coastal waters

Adverse effects of invasive alien species (IAS), or biological pollution, is an increasing problem in marine coastal waters, which remains high on the environmental management agenda. All maritime countries need to assess the size of this problem and consider effective mechanisms to prevent introductions, and if necessary and where possible to monitor, contain, control or eradicate the introduced impacting organisms. Despite this, and in contrast to more enclosed water bodies, the openness of marine systems indicates that once species are in an area then eradication is usually impossible. Most institutions in countries are aware of the problem and have sufficient governance in place for management. However, there is still a general lack of commitment and concerted action plans are needed to address this problem. This paper provides recommendations resulting from an international workshop based upon a large amount of experience relating to the assessment and control of biopollution.

Vulnerability of benthic habitats to the aquatic invasive species

A comparative vulnerability analysis of 16 selected benthic habitat types in the SE Baltic Sea waters and the Curonian lagoon, including Klaipeda strait, was performed using long-term monitoring datasets (1980–2003) and results of several other surveys in the lagoon and the sea. Results indicated that invasive species richness (number of alien species per habitat) in lagoon habitats was significantly higher than in the sea. Habitats formed by artificial rock and stone, sand, mud, and habitats modified by zebra mussel shell deposits appeared to be the most invaded. Highest invasive species richness occurred in habitats with high native species richness indicating that the main factors driving native species distribution (such as favourable physical conditions, habitat alterations generated by human or/and biotic activities) are also driving aquatic invaders. Physical factors distinguished to be the most important for native and invasive species distribution were salinity, depth range (expressed by the maximal and minimal depths difference within a habitat), shallowness of a habitat (expressed by a minimal depth), and availability of a hard substrate.

INVASION OF THE NORTH AMERICAN AMPHIPOD (GAMMARUS TIGRINUS SEXTON, 1939) INTO THE CURONIAN LAGOON, SOUTH-EASTERN BALTIC SEA

The North American amphipod (Gammarus tigrinus Sexton, 1939) was found in the Lithuanian part of the Curonian Lagoon in September 2004. In the littoral part, the distribution of the species was restricted to the area of seawater inflows, within a distance of up to 23 km upstream from the sea. The species was present in all types of the habitats sampled (reeds, mixed and soft bottoms) and its distribution showed a continuous rather than fragmented pattern. In most cases, the species was absent in enclosed depositional environments with mixed substrates and the presence of mud. Obessogammarus crassus (G. O. Sars) was the only crustacean species always found in the presence of the new invader G. tigrinus, whereas other species showed a higher degree of habitat discrimination within the stations. Along with the other two introduced crustaceans O. crassus and Pontogammarus robustoides (G. O. Sars), G. tigrinus showed the highest occurrence (79%) in the salinity range of its recent distribution in the lagoon. A...

History and Success of an Invasion into the Baltic Sea: The Polychaete Marenzelleria cf. Viridis, Development and Strategies

In the mid 1980s, a new polychaete appeared in coastal waters of the Baltic Sea and rapidly became an important faunistic element. The identification of this spionid as Marenzelleria cf. viridis indicated North America as the most likely area of origin. The history of invasion into the Baltic Sea is outlined. Sound taxonomic experience and competence was and is necessary to elucidate the background when dealing with bioinvasions. A review of taxonomic problems of the genus Marenzelleria is given. Based on long time series we could draw a picture on the species strategy in stressed habitats. Three coastal areas were selected to demonstrate the role of environmental factors facilitating Marenzelleria invasion in the Baltic Sea in the last decade. This review deals with the expansion and niching of an allochthonous species and its influence on the indigenous macrozoobenthos. Both the life history and physiology of Marenzelleria make it well adapted to life in brackish water conditions, occupying a niche in an environment with low species diversity.

Climate-related Marine Ecosystem Change

This chapter deals with climate-related changes in the marine ecosystem of the Baltic Sea. The Baltic Sea is often described as one of the world’s largest brackish water bodies. It has a unique combination of oceanographic, climatic, and geographic features. Most important in this context is: the sea is a nearly enclosed area having a water residence time of 30 years, due to restricted water exchange through the Danish Straits. It is situated in northern Europe and has, therefore, some arctic characteristics and a pronounced seasonality. It is affected alternately by continental and marine climatic effects. It has a catchment area approximately four times larger than the sea itself, while it is as the same time very shallow, with an average depth of only 56 m, having thus a relatively small water body. Seasonal vertical mixing of the water reaches a depth of 30–50 m and contributes to resuspension of nutrients and pollutants. In deeper parts, a permanent halocline appears, below which anoxia is common and interrupted only by major inflows of North Sea water.

Invaders in Suspension-Feeder Systems: Variations along the Regional Environmental Gradient and Similarities between Large Basins

Biological invasions increasingly alter taxonomical and functional structure of benthic communities. Among the invasive benthic invertebrates, the suspension-feeders are the most widespread type. Species belonging to that trophic group constitute from half to two thirds of total invasive species in various European seas. The importance of the alien suspension-feeders is particularly obvious in evolutionary young, species poor brackish water bodies, such as the Baltic Sea. We analyzed changes in suspension-feeder systems formed by both alien and native species along the salinity and depth gradients from a river mouth (the Curonian Lagoon) down to the halocline area of the Baltic Proper. There was a clear shift in the biomass dominance from the alien species in the lagoon to the native suspension-feeders in the sea. Both the native and alien obligatory suspension-feeders occupied shallow coastal marine and lagoon habitats and did not form stable communities below the 30 m depth.

Species strategy near its boundary : The Marenzelleria cf. Viridis (Polychaeta, Spionidae) case in the South-Eastern Baltic Sea

The invasive polychaete worm Marenzelleria cf. viridis spread into various coastal habitats in the Baltic Sea. The estimated limits regarding its salinity tolerance obtained from different laboratory experiments alone only rarely explain the actual species boundaries in nature, e.g. in the Curonian lagoon. Therefore, a field study was carried out aimed at to define, how a population maintains itself in a dynamic estuarine habitat with rapid and irregular changing salinity (annual mean 3 PSU, range of variation from 0 to 7.5 PSU). Under these conditions the species females reached maturity. However, during the final reproduction phase their spawning was delayed and oosorption started. It was estimated that roughly 0.05% of the nearby sea population offspring was transported to the estuary but most of the pelagic larvae were not able to develop beyond the 10 segments stage. It seems that the estuarine benthic population is maintained by migration of the species benthic stages. This mode probably is more efficient in comparison to dispersal by pelagic larvae when a species colonises stressed and dynamic environments.

Density effects on the clearance rate of the zebra mussel Dreissena polymorpha: flume study results

Zebra mussel filtration rates and regulating factors have been addressed earlier in a number of studies. Still, only a few of them have taken into consideration the refiltration phenomenon, and therefore the direct extrapolation of experimental results may only give the potential filtering capacity, and hence, over- or underestimate the actual amount of seston being removed by zebra mussels in an ecosystem. The current experimental study aimed to gain insight into the refiltration effect on the clearance rate of the zebra mussels at relatively high seston concentrations, and its potential role in controlling the filtration efficiency of the zebra mussel population. The experiment was conducted in a laboratory flume following the Latin squares design with one fixed (mussel density) and three random factors (initial total particulate matter (TPM) concentration, flume “wall effect” and distance from the flume inflow area) considered. The results showed the significant effects of mussel density and the TPM concentration on the effective clearance rate (ECR) of zebra mussels. The higher ECR values were obtained at denser mussel clumps and lower TPM concentrations. The flume “wall effect” had no significant effect on the ECR, whereas the distance from the flume inflow area appeared to have a significant impact. A positive relationship between ECR and the zebra mussel density was most evident in the proximity of the TPM source. Based on the results, we assume that at high TPM concentration, refiltration may assert itself by the elevated net clearance rate of mussels within dense clumps compared to that of mussels at relatively low individual densities. This should be taken into consideration while modelling and assessing the role of the zebra mussel in energy flow and redistribution of organic matter in an ecosystem.

Internet Database on Alien Species in the Baltic Sea

An Internet Database on aquatic alien species in the Baltic Sea area was developed as an initiative of the Baltic Marine Biologists’ Working Group on Nonindigenous Estuarine and Marine Organisms in 1997; in 2000 a new concept of the online Database appeared with support received from the Baltic Marine Environment Protection Commission (HELCOM). This regional project encourages the exchange of data within the Baltic Sea area, providing a competent system regarding biological invasions, vectors of introduction, spread of alien species and their impacts on environment and economy. The Baltic Database represents an important regional node for a future global information system on invasive species.

Revision pre-ingestive selection efficiency definition for suspension feeding bivalves: facilitating the material fluxes modelling

The importance of the particle selective feeding of bivalves becomes more evident and it is necessary to incorporate this phenomenon into ecological models in order to reflect correctly the material fluxes inside the organism and ecosystem as well. The problems related to the modelling of organic matter selection are considered in this paper and a new definition of pre-ingestive selection efficiency is proposed. It differs from the classical one in using the organic material fraction in ingested food instead of pseudofaeces. The newly defined selection efficiency exhibits an advantage in simplified shape of experimental relationship to the organic matter fraction in seston and easier derivation of formulas related to mathematical food processing formulation.