Han J. Lindeboom

Offshore wind park monitoring programmes, lessons learned and recommendations for the future.

Over a decade of monitoring offshore wind park environmental impact triggered a reflection on the overall objectives and how to best continue with the monitoring programmes. Essentially, basic monitoring has to be rationalised at the level of the likelihood of impact detection, the meaningfulness of impact size and representativeness of the findings. Targeted monitoring is crucial and should continue to be applied to disentangle processes behind observed impacts, for instance the overarching artificial reef effect caused by wind parks. The major challenge, however, remains to achieve a reliable assessment of the cumulative impacts. A continuous international consultation and collaboration with marine scientists, managers, government officials and industry will be needed to ensure an optimisation of the future monitoring programmes.

Marine Fouling Assemblages on Offshore Gas Platforms in the Southern North Sea: Effects of Depth and Distance from Shore on Biodiversity

Offshore platforms are known to act as artificial reefs, though there is on-going debate on whether this effect is beneficial or harmful for the life in the surrounding marine environment. Knowing what species exist on and around the offshore platforms and what environmental variables influence this species assemblage is crucial for a better understanding of the impact of offshore platforms on marine life. Information on this is limited for offshore platforms in the southern North Sea. This study aims to fill this gap in our knowledge and to determine how the composition and the abundance of species assemblages changes with depth and along a distance-from-shore gradient. The species assemblages on five offshore gas platforms in the southern North Sea have been inventoried using Remotely Operated Vehicles inspection footage. A total of 30 taxa were identified. A Generalised Additive Model of the species richness showed a significant non-linear relation with water depth (p = 0.001): from a low richness in shallow waters it increases with depth until 15–20 m, after which richness decreases again. Using PERMANOVA, water depth (p≤0.001), community age (p≤0.001) and the interaction between distance from shore and community age (p≤0.001) showed a significant effect on the species assemblages. Future research should focus on the effect additional environmental variables have on the species assemblages.

Utilization of seagrass habitats by juvenile groupers and snappers in Banten Bay, Banten Province, Indonesia

Coastal development in Banten Bay, Indonesia, decreased seagrass coverage to only 1.5% of its surface area. We investigated the importance of seagrass as habitat for juvenile groupers (Serranidae) and snappers (Lutjanidae), by performing beam trawl hauls on a weekly basis in two seagrass locations and one mudflat area, and monthly trawl hauls in three different microhabitats (dense, mixed and patchy seagrass) in one of the seagrass locations. We studied the effects of location and microhabitat, as well as temporal patterns (diel, weekly and monthly) on the probability of occurrence and abundance of the most abundant grouper (Orange-spotted grouper, Epinephelus coioides) and snapper (Russell’s snapper, Lutjanus russellii). We found that both species were almost exclusively found in seagrass locations, with a preference for microhabitats of high complexity (dense and mixed microhabitats). L. russellii had a higher probability of catch and abundance during the night, most probably because of its ability to avoid the beam trawl during daytime sampling. In addition there was an effect of week and month on the presence and abundance of both species, but patterns were unclear, probably because of high fishing pressure on juvenile groupers and snappers by push net fishermen. Groupers and snappers mainly fed on abundant shrimps, and to a lesser extent on fish. Moreover, juveniles find protection against predators in seagrass, which confirmed the critical role of quantity and quality of seagrass areas for juvenile groupers and snappers in Banten Bay.

Ecosystem model of the western Wadden Sea: A bridge between science and management?

This paper describes the construction, validation and application of a mathematical ecosystem model of the western Wadden Sea. This model is based upon the Ems-Dollard ecosystem model, but also includes a two-dimensional transport submodel, a benthic and epibenthic sublitoral submodel and nutrient regeneration. In 1986, an extensive field programme was executed to collect data for model validation. Apart from the subtidal processes the validation indicates that the model simulates the different state variables reasonably well. The applicability of the model for management purposes was tested in four case studies concerning: dredging activities, eutrophication, commercial mussel cultrue and oil spills and other calamities. It is concluded that the western Wadden Sea model in general is a useful tool in evaluating the impact of certain anthropogenic activities in the area.

Short-term impact of deep sand extraction and ecosystem-based landscaping on macrozoobenthos and sediment characteristics.

We studied short-term changes in macrozoobenthos in a 20m deep borrow pit. A boxcorer was used to sample macrobenthic infauna and a bottom sledge was used to sample macrobenthic epifauna. Sediment characteristics were determined from the boxcore samples, bed shear stress and near-bed salinity were estimated with a hydrodynamic model. Two years after the cessation of sand extraction, macrozoobenthic biomass increased fivefold in the deepest areas. Species composition changed significantly and white furrow shell (Abra alba) became abundant. Several sediment characteristics also changed significantly in the deepest parts. Macrozoobenthic species composition and biomass significantly correlated with time after cessation of sand extraction, sediment and hydrographical characteristics. Ecosystem-based landscaped sand bars were found to be effective in influencing sediment characteristics and macrozoobenthic assemblage. Significant changes in epifauna occurred in deepest parts in 2012 which coincided with the highest sedimentation rate. We recommend continuing monitoring to investigate medium and long-term impacts.

Preface: the WinMon.BE 2013 conference: steps towards an efficient and effective offshore wind farm environmental impact assessment

The race for a timely combat of climate change through the reduction of greenhouse gasses such as carbon dioxide has pushed renewable energy developments to a higher echelon. At present, wind is one of the most profitable sources of exploitable renewable energy. Wind farms are popping up at many places worldwide. Their expansion on land, however is constrained, because sites where wind farms do not conflict with the high-quality environmental standards of the local community are limited. Being uninhabited, the marine environment offers a vast area for wind farm development. Being uninhabited, however, does not equal not being subject to impact. The sea and oceans host rich ecosystems, many of which have and continue to deliver priceless and indispensable goods and services to mankind. Offshore wind farm development is hence subject to environmental impact assessment and residual impacts should be carefully monitored. Most, if not all, current offshore wind farms are accompanied by an environmental monitoring programme. These programmes should be considered the ‘finger on the pulse’ to avoid surpassing critical impact levels. They further ensure the achievement of the knowledge base needed to adjust new developments in a scientifically and environmentally sensitive and sound manner. On 26–28 November 2013, the Royal Belgian Institute of Natural Sciences organised the international scientific WinMon.BE 2013 conference on ‘‘Environmental impacts of offshorewind farms: learning from the past to optimise future monitoring programmes’’ (http:// odnature.naturalsciences.be/winmonbe2013).During the Guest editors: Steven Degraer, Jennifer Dannheim, Andrew B. Gill, Han Lindeboom & Dan Wilhelmsson / Environmental impacts of offshore wind farms