Search results

Subscribe to an always-updated RSS feed.

Offshore wind farms and the attraction–production hypothesis: insights from a combination of stomach content and stable isotope analyses: Offshore wind farms (OWFs) act as arti- ﬁcial reefs, attracting high abundances of ﬁsh, which could potentially increase their local production. This study investigates the feeding ecology of ﬁsh species that abundantly occur at artiﬁcial habitats, such as OWFs, by examining the short- and the long-term dietary composition of ﬁve species: the benthopelagic Gadus morhua and Trisopterus luscus, the pelagic Scomber scombrus and Trachurus trachurus, and the benthic Myoxocephalus scorpioides. We conducted combined stomach content and stable isotope analyses to examine the short- and the time-integrated dietary composition, respectively. Our results indicated that benthopelagic and benthic species utilize artiﬁcial reefs, such as OWFs, as feeding grounds for a prolonged period, since both analyses indicated that they exploit fouling organisms occurring exclusively on artiﬁcial hard substrates. Trachurus trachurus only occasionally uses artiﬁcial reefs as oases of highly abundant resources. Scomber scombrus does not feed on fouling fauna and therefore its augmented presence in OWFs is probably related to reasons other than the enhanced food availability. The long-termed feeding preferences of benthic and benthopelagic species contribute to the hypothesis that the artiﬁcial reefs of OWFs could potentially increase the ﬁsh production in the area. However, this was not supported for the pelagic species.
Located in Library / RBINS Staff Publications 2022
Offshore Wind Farm Footprint on Organic and Mineral Particle Flux to the Bottom.: Offshore wind farms (OWFs) are an important source of renewable energy accounting for 2.3% of the European Union’s electricity demand. Yet their impact on the environment needs to be assessed. Here, we couple a hydrodynamic (including tides and waves) and sediment transport model with a description of the organic carbon and mineral particle dynamics in the water column and sediments. The model is applied to the Belgian Coastal Zone (BCZ) where OWFs currently occupy 7% of its surface area which is estimated to double in the next 5 years. The impact of OWFs on the environment is represented through the ﬁltration of the water column and fecal pellets production by the blue mussel, the dominant fouling organism. Our model simulations show that the impact of biodeposition on the mud particle sedimentation and on sediment composition is small compared to the ﬂuxes associated with tidal deposition and resuspension and the lateral inputs. In contrast, the total organic carbon (TOC) ﬂux to the sediment is signiﬁcantly altered inside the OWF perimeters and TOC deposition is increased up to 50% in an area 5 km around the monopiles. Further away, the TOC ﬂux to the bottom decreases with a notable effect up to 30 km away. The major changes are found along the direction of the main residual current and tidal ellipse’s major axis. In addition, sub-mesoscale gyres act as retention areas with increased carbon deposition. A future OWF in the BCZ will be located close to gravel beds in a Natura 2000 area, considered as vulnerable habitats and biodiversity hotspots. The different scenarios for this OWF, varying in turbine number and positioning, are compared in terms of impact on the carbon and mineral particle deposition ﬂux in the BCZ and, particularly, to these gravel beds. The scenarios show that the number of turbines has only a slight impact on the TOC deposition ﬂux, unlike their positioning that signiﬁcantly alters the TOC ﬂux to the gravel beds. The TOC deposition ﬂux exceeds 50%, when the turbines are placed next to the gravel beds; while a limited increase is simulated, when the turbines are located the farthest possible from them.
Located in Library / RBINS Staff Publications 2021
Subtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning: Subtidal natural hard substrates (SNHS) promote occupancy by rich benthic communities that provide irreplaceable and fundamental ecosystem functions, representing a global priority target for nature conservation and recognised in most European environmental legislation. However, scientiﬁcally validated methodologies for their quantitative spatial demarcation, including information on species occupancy and ﬁne-scale environmental drivers (e.g., the effect of stone size on colonisation) are rare. This is, however, crucial information for sound ecological management. In this investigation, high-resolution (1 m) multibeam echosounder (MBES) depth and backscatter data and derivates, underwater imagery (UI) by video drop-frame, and grab sediment samples, all acquired within 32 km²of seaﬂoor in offshore Belgian waters, were integrated to produce a random forest (RF) spatial model, predicting the continuous distribution of the seaﬂoor areal cover/m² of the stones’ grain sizes promoting colonisation by sessile epilithic organisms. A semi-automated UI acquisition, processing, and analytical workﬂow was set up to quantitatively study the colonisation proportion of different grain sizes, identifying the colonisation potential to begin at stones with grain sizes Ø ≥ 2 cm. This parameter (i.e., % areal cover of stones Ø ≥ 2 cm/m²) was selected as the response variable for spatial predictive modelling. The model output is presented along with a protocol of error and uncertainty estimation. RF is conﬁrmed as an accurate, versatile, and transferable mapping methodology, applicable to area-wide mapping of SNHS. UI is conﬁrmed as an essential aid to acoustic seaﬂoor classiﬁcation, providing spatially representative numerical observations needed to carry out quantitative seaﬂoor modelling of ecologically relevant parameters. This contribution sheds innovative insights into the ecologically relevant delineation of subtidal natural reef habitat, exploiting state-of-the-art underwater remote sensing and acoustic seaﬂoor classiﬁcation approaches.
Located in Library / RBINS Staff Publications 2022
Climate change effects on the ecophysiology and ecological functioning of an offshore wind farm artiﬁcial hard substrate community: In the effort towards a decarbonised future, the local effects of a proliferating offshore wind farm (OWF) industry add to and interact with the global effects of marine climate change. This study aimed to quantify potential ecophysiolog- ical effects of ocean warming and acidiﬁcation and to estimate and compare the cumulative clearance potential of suspended food items by OWF epifauna under current and future climate conditions. To this end, this study combined ecophysiological responses to ocean warming and acidiﬁcation of three dominant colonising species on OWF artiﬁcial hard substrates (the blue mussel Mytilus edulis, the tube-building amphipod Jassa herdmani and the plumose anemone Metridium senile). In general, mortality, respiration rate and clearance rate increased during 3- to 6-week experimental exposures across all three species, except for M. senile, who exhibited a lower clearance rate in the warmed treatments (+3 °C) and an insensitivity to lowered pH (−0.3 pH units) in terms of survival and respiration rate. Ocean warming and acidiﬁcation affected growth antagonistically, with elevated temperature being beneﬁcial for M. edulis and lowered pH being beneﬁcial for M. senile. The seawater volume potentially cleared from suspended food particles by this AHS colonising community increased signiﬁcantly, extending the affected distance around an OWF foundation by 9.2% in a future climate scenario. By using an experimental multi-stressor approach, this study thus demonstrates how ecophysiology underpins functional responses to climate change in these environments, highlighting for the ﬁrst time the integrated, cascading potential effects of OWFs and climate change on the marine ecosystem.
Located in Library / RBINS Staff Publications 2022
Small suspension-feeding amphipods play a pivotal role in carbon dynamics around offshore man-made structures: The establishment of artificial hard substrates (i.e. offshore wind farms and oil and gas platforms) on marine soft sediments increases the available habitat for invertebrate communities that would otherwise be restricted to natural hard bottoms. Suspension feeding invertebrates clear a significant amount of particles from the water column and release organic matter in the form of feces, influencing the basis of marine food webs and affecting surrounding environments. Artificial structures in the southern North Sea are dominated by a suspension-feeding crustacean in terms of abundance and sometimes even biomass: the amphipod Jassa herdmani. Animal densities of this tiny biofouler are known to exceed 1 million individuals per m2. Despite their small body sizes and their simple filter apparatus, we hypothesized that J. herdmani is a highly effective suspension feeder with a significant impact on neighboring communities due to its high abundances. In a feeding experiment, individuals of J. herdmani were provided with either an algal or an animal diet under two different temperature regimes. Clearance rates and fecal-pellet carbon (FPC) were measured. The results revealed high clearance rates and subsequent FPC, which were more pronounced at the higher temperature. Furthermore, clearance rates and FPC varied insignificantly with different food items. We further used the current findings for upscaling calculations to the total number of offshore windfarms and oil and gas platforms in the southern North Sea. Our calculations indicated that J. herdmani alone clears 0.33 – 4.71 km3 water per year in the southern North Sea. At the same time, these amphipods release 255 – 547 tons of carbon per year by means of defecation, thus enriching the surrounding soft sediments with organic matter. Our study highlights that tiny amphipods can mediate indirect effects of man- made structures in the North Sea, which could have a profound impact on pelagic and benthic habitats.
Located in Library / RBINS Staff Publications 2022
WinMon.BE, Using a decade of WinMon.BE results to plan for the future: Located in Library / RBINS Staff Publications 2021
Protecting the marine environment whilst installing offshore windfarms: the effect of scour protection layers on benthic biodiversity: The North Sea will soon see the installation of a higher number of wind turbine foundations, greatly expanding the habitat options for reef species. These offshore structures constitute a new, artificial, hard substratum habitat on the Belgian continental shelf, where the seafloor is primarily made up of muddy and sandy sediment. The possibility of co-designing offshore wind farms with more microhabitats through increasing habitat complexity is one method for the multiple uses of wind farms. This method is known as nature-inclusive building. The structure and dynamics of ecological communities are significantly influenced by habitat complexity. Hence, an increased complexity frequently results in greater species variety and abundance. The objective of this study was to investigate whether adding complexity to the scour protection layer (SPL) increased the diversity and functionality of the ecosystem already present at the bottom of wind turbines (macrobenthos community). To study this, three different variables of 76 species were analysed: richness, biomass, and abundance. Despite being the first time to manipulate the SPL of wind farms, it has been possible to observe and demonstrate that the complexity of these structures affects the ecosystem’s richness. Of the four different treatments, a greater number of species were observed in the most complex ones (3 and 4) compared to the others. In addition, although there were no significant differences, trends of higher biomass of certain species (belonging to decapods and sea anemones) were observed in the presence of higher complexity. Conversely, the constant presence of amphipods was observed across all the treatments. With this study, we wanted to emphasise the importance of the artificial reef effect of the SPL and, together with the microhabitats that it can provide, if at the time of its construction, an attempt is made from an “eco-friendlier” perspective, combining the knowledge of ingested together with the biological. In addition, it provides more knowledge and understanding of this methodology by improving it and obtaining results more similar to those expected in the future.
Located in Library / RBINS Staff Publications 2022
Physiological response to seawater pH of the bivalve Abra alba, a benthic ecosystem engineer, is modulated by low pH: The presence and behaviour of bivalves can affect the functioning of seafloor sediments through the irrigation of deeper strata by feeding and respiring through siphonal channels. Here, we investigated the physiological response and consecutive impact on functioning and body condition of the white furrow shell Abra alba in three pH treatments (pH = 8.2, pH = 7.9 and pH = 7.7). Although no pH effect on survival was found, lowered respiration and calcification rates, decreased energy intake (lower absorption rate) and increased metabolic losses (increased excretion rates) occurred at pH ~ 7.7. These physiological responses resulted in a negative Scope for Growth and a decreased condition index at this pH. This suggests that the physiological changes may not be sufficient to sustain survival in the long term, which would undoubtedly translate into consequences for ecosystem functioning.
Located in Library / RBINS Staff Publications 2022
Generalized changes of benthic communities after construction of wind farms in the southern North Sea: Over the last years, the development of offshore renewable energy installations such as offshore wind farms led to an increasing number of man-made structures in marine environments. Since 2009, benthic impact monitoring programs were carried out in wind farms installed in the southern North Sea. We collated and analyzed data sets from three major monitoring programs. Our analysis considered a total of 2849 sampling points converted to a set of biodiversity response metrics. We analyzed biodiversity changes related to the implementation of offshore wind farms and generalized the correlation of these changes with spatial and temporal patterns. Our results demonstrate that depth, season and distance to structure (soft-bottom community) consistently determined di- versity indicators and abundance parameters, whereas the age and the country affiliation were significantly related to some but not all indices. The water depth was the most important structuring factor for fouling communities while seasonal effects were driving most of the observed changes in soft-sediment communities. We demonstrate that a meta-analysis can provide an improved level of understanding of ecological patterns on large- scale effects of anthropogenic structures on marine biodiversity, which were not visible in single monitoring studies. We believe that meta-analyses should become an indispensable tool for management of offshore wind farm effects in the future, particularly in the view of the foreseen development of offshore renewable energies. This might lead to a better picture and more comprehensive view on potential alterations. However, this requires a modern open-source data policy and data management, across institutions and across national borders.
Located in Library / RBINS Staff Publications 2022
Generalized changes of benthic communities after construction of wind farms in the southern North Sea: Over the last years, the development of offshore renewable energy installations such as offshore wind farms led to an increasing number of man-made structures in marine environments. Since 2009, benthic impact monitoring programs were carried out in wind farms installed in the southern North Sea. We collated and analyzed data sets from three major monitoring programs. Our analysis considered a total of 2849 sampling points converted to a set of biodiversity response metrics. We analyzed biodiversity changes related to the implementation of offshore wind farms and generalized the correlation of these changes with spatial and temporal patterns. Our results demonstrate that depth, season and distance to structure (soft-bottom community) consistently determined di- versity indicators and abundance parameters, whereas the age and the country affiliation were significantly related to some but not all indices. The water depth was the most important structuring factor for fouling communities while seasonal effects were driving most of the observed changes in soft-sediment communities. We demonstrate that a meta-analysis can provide an improved level of understanding of ecological patterns on large- scale effects of anthropogenic structures on marine biodiversity, which were not visible in single monitoring studies. We believe that meta-analyses should become an indispensable tool for management of offshore wind farm effects in the future, particularly in the view of the foreseen development of offshore renewable energies. This might lead to a better picture and more comprehensive view on potential alterations. However, this requires a modern open-source data policy and data management, across institutions and across national borders.
Located in Library / RBINS Staff Publications 2022

« Previous 10 items Next 10 items » 1 2 3 4 5