Mathias H. Andersson

Epibenthic colonization of concrete and steel pilings in a cold-temperate embayment: a field experiment

With large-scale development of offshore wind farms, vertical structures are becoming more common in open water areas. To examine how vertical structures of different materials may be colonized by epibenthic organisms, an experiment was carried out using steel and concrete pilings constructed to resemble those commonly used in wind farm constructions as well as in bridges, jetties and oil platforms. The early recruitment and succession of the epibenthic communities were sampled once a month for the first 5 months and then again after 1 year. Further, the fish assemblages associated with the pillars were sampled and compared to natural areas. The main epibenthic species groups, in terms of coverage, differed between the two materials at five out of six sampling occasions. Dominant organisms on steel pillars were the barnacle Balanus improvisus, the calcareous tubeworm Pomatoceros triqueter and the tunicate Ciona intestinalis. On the concrete pillars, the hydroid Laomedea sp. and the tunicates Corella parallelogramma and Ascidiella spp. dominated. However, there was no different in coverage at different heights on the pillars or in biomass and species abundance at different directions (north-east or south-west) 5 months after submergence. Fish showed overall higher abundances and species numbers on the pillars (but no difference between steel and concrete) compared to the surrounding soft bottom habitats but not compared to natural vertical rock walls. Two species were attracted to the pillars, indicating a reef effect; Gobiusculus flavescens and Ctenolabrus rupestris. The bottom-dwelling gobies, Pomatoschistus spp., did not show such preferences.

Fish and sessile assemblages associated with wind-turbine constructions in the Baltic Sea

Offshore wind farms are being built at a high rate around the world to meet the demand for renewable energy. We studied fish and sessile communities on and around offshore wind-turbine foundations ...

The marine splash midge Telmatogon japonicus (Diptera; Chironomidae) - extreme and alien?

We found all developmental stages of the midge Telmatogeton japonicus (Chironomidae) on offshore windmills near the major Swedish seaport Kalmar in the southern Baltic Sea. This might be the first record of an insect species really inhabiting the offshore areas of the Baltic Sea. A thorough analysis of previous findings of the species, its history in Europe and its ecology indicates that T. japonicus quite likely is an alien species in Europe introduced from the Pacific Ocean. Shipping is probably the vector, as all records in the Baltic Sea and several from the Eastern Atlantic Sea are near major seaports. Our analysis further suggests that T. japonicus might be both advantageous and disadvantageous to native species in the Baltic Sea. T. japonicus should be kept under observation within monitoring programmes as it might expand its distribution as a result of the construction of new windmills in the Baltic Sea and elsewhere in European marine and brackish water habitats.

Particle motion measured at an operational wind turbine in relation to hearing sensitivity in fish

The effect of sound pressure on the hearing of fish has been extensively investigated in laboratory studies as well as in field trials in contrast to particle motion where few studies have been carried out. To improve this dearth of knowledge, an instrument for measuring particle motion was developed and used in a field trial. The particle motion is measured using a neutrally buoyant sphere, which co-oscillates with the fluid motion. The unit was deployed in close vicinity to a wind turbine foundation at Utgrunden wind farm in the Baltic Sea. Measurements of particle motion were undertaken at different distances from the turbine as well as at varying wind speeds. Levels of particle motion were compared to audiograms for cod (Gadus morhua L.) and plaice (Pleuronectes platessa L.).

Effects of Pile Driving on the Behavior of Cod and Sole

Studies on the effects of offshore wind farm construction on marine life have focused on behavioral reactions in porpoises and seals (Thomsen et al. 2006). The effects on fish have only very recently come into the focus of scientists, regulators, and stakeholders (Popper and Hastings 2009). Pile-driving noise during construction is of particular concern because the very high sound pressure levels (see Thomsen et al. 2006) could potentially prevent fish from reaching breeding or spawning sites, finding food, and acoustically locating mates that could result in long-term effects on reproduction and population parameters. There is also the possibility that avoidance reactions might displace fish away from potential fishing grounds that could lead to reduced catches (see, e.g., Engas et al. 1996). However, the nature and extent of behavioral reactions of marine fish due to pile driving have not been studied in controlled experiments. Therefore, the impacts of pile driving on marine fish remain unknown.

Underwater Particle Acceleration Induced by a Wind Turbine in the Baltic Sea

During the last decade, there has been a major interest in wind energy production. The number of offshore wind farms is increasing rapidly. Several nations are planning to switch to “green” power, increasing the numbers even more. The public awareness and the general focus on the environment require that wind-based energy should be ecologically harmless. Lately, it has been realized that the aquatic environment is also a soundscape, not at least due to the fact that many species make use of sound for communication, mating, finding prey, and avoiding predators. Furthermore, most studies have been concerned with the effect of the sound pressure component of sound, even though many species are sensitive to particle motion. For this reason, a particle motion sensor was built and deployed in close vicinity to a wind turbine where the generated particle motion in the ocean was characterized. The results are presented here.

Do Ocean-Based Wind Farms Alter the Migration Pattern in the Endangered European Silver Eel (Anguilla anguilla) Due to Noise Disturbance?

Numerous offshore wind farms have been built and will increase in the near future in the coastal areas of northern Europe. These locations are often in the direct path of migrating Anguilla anguilla (European silver eel) on their 5,000- to 6,000-km journey from Europe to the Sargasso Sea. At a certain time in their life that occurs between the ages of 6 and 20, A. anguilla start their long spawning migration. When this occurs, an irreversible physiological transformation starts in which the eyes and pectoral fins are enlarged, the skin color changes, and the digestive organs are regressed. Additionally, they stop feeding during the migration phase, which gives A. anguilla a limited amount of stored energy. If the fish are disturbed or hindered, the energy reserves might not be enough for them to reach their destination or it could, at least, result in limited spawning success. This effect could be devastating to the already highly threatened A. anguilla population that is listed as “critically endangered” in the International Union for Conservation of Nature (IUCN) red list.

Operational wind farm noise and shipping noise compared with estimated zones of audibility for four species of fish.

A comparison between different underwater sound sources such as ships and operational wind farms are not straightforward to perform due to their qualitative difference in signal properties. However, in order to study possible effects of noise on fish, this comparison has to be made, and possible cumulative effects investigated. This study shows that a wind farm located in a shallow area in the Baltic Sea will add significant noise levels to the region even though intense shipping activities occur. This is due to the fact that the wind farm produces a strong tonal component at 127 Hz, a frequency otherwise relatively unaffected by shipping noise. The results were obtained by developing a numerical acoustic model of the wind farm taking account of their integrated effect. The model was evaluated against measurements performed at several distances from the wind farm during various weather conditions. Additionally, zones of audibility for cod, herring, salmon, and European eel were estimated.

Behavioral reactions of cod and sole to playback of pile driving sound.

The effect of anthropogenic underwater sound on fish has become an important environmental issue. Pile‐driving noise during construction is of particular concern as the very high sound pressure levels could potentially prevent fish from reaching breeding or spawning sites, finding food, and acoustically locating mates. This could result in long‐term effects on reproduction and populationparameters. Additionally, avoidance reactions might result in displacement away from potential fishing grounds and lead to reduced catches. However, reaction thresholds and therefore the impacts of pile driving on the behavior of fish are completely unknown. Pile‐driving noise was played back to cod and sole held in two large (40 m) net pens located in a quiet bay. Movements of the fish were analyzed using a novel acoustic tracking system. Received sound pressure level and particle motion were measured during the experiments. The results show significant movement responses to the pile‐driving stimulus in both species at re...