Article

Flatfish habitat use near North America's first offshore wind farm

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Abstract

Use of offshore wind power as a renewable energy source is underway in North America with the construction of the pilot, five wind turbine, Block Island Wind Farm, off Rhode Island, USA. Demersal trawl monitoring was conducted in two reference areas and near the wind farm that allowed an examination of whether flatfish abundances, size, and condition differed between baseline, construction, and operation time periods. Seven flatfish, (American plaice Hippoglossoides platessoides, fourspot flounder Paralichthys oblongus, Gulf stream flounder Citharichthys arctifrons, summer flounder Paralichthys dentatus, windowpane flounder Scophthalmus aquosus, winter flounder Pseudopleuronectes americanus, and yellowtail flounder Pleuronectes ferruginea) were collected in the study area. Winter flounder, windowpane and fourspot flounder accounted for 83% of all flatfish collected. Flatfish exhibited spatial and temporal variation in abundance, size, and condition, but this variation was not consistent with either positive or negative effects of wind farm construction or operation. Lower winter flounder abundances during the pile-driving time period and higher abundances during the cable-laying time period in the reference and wind farm areas suggest regionwide population fluctuations occurred. Although noise from pile driving may have been detectable in the reference areas, other flatfish abundances were not lower during this time period. Although no artificial reef effect was found for flatfish, negative impacts from construction activity and wind farm operation also were not evident.

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... The consequences for soft-sediment species, such as flatfish, are less studied (Vandendriessche et al., 2015). Since flatfish spend the majority of their life in close contact with the seabed, their spatial distribution response to the introduction of artificial hard substrates might differ from that of (bentho)pelagic fish species (Wilber et al., 2018). A number of studies found no attraction of flatfish towards the scour protection layer (SPL) (Krone et al., 2017;van Hal et al., 2017) and no clear positive nor negative effects at the wind farm level (Lindeboom et al., 2011;Stenberg et al., 2015;Wilber et al., 2018). ...
... Since flatfish spend the majority of their life in close contact with the seabed, their spatial distribution response to the introduction of artificial hard substrates might differ from that of (bentho)pelagic fish species (Wilber et al., 2018). A number of studies found no attraction of flatfish towards the scour protection layer (SPL) (Krone et al., 2017;van Hal et al., 2017) and no clear positive nor negative effects at the wind farm level (Lindeboom et al., 2011;Stenberg et al., 2015;Wilber et al., 2018). However, these studies might have missed an effect, as refuge effects are often only observed after a prolonged period (> 5 years) (Babcock et al., 2010;De Backer et al., 2020). ...
... Other studies that looked at flatfish abundances in between the turbines of OWFs found no significant wind farm effect (Lindeboom et al., 2011;Wilber et al., 2018). The average time for the first detection of a refuge effect on a target species in a fisheries exclusion zone is over 5 years (Babcock et al., 2010). ...
Article
We investigated how the distribution of plaice Pleuronectes platessa, a typical soft-sediment fish species, has been affected by the introduction of hard substrate [turbines and scour protection layer (SPL)] at both turbine and wind farm scale in two Belgian offshore wind farms (OWFs). Diving transects (40 m) at 11 monopiles revealed four times higher plaice abundances on the sandy patches of the SPL (average radius 16.5 m) compared to the surrounding sand. We suggest that the configuration of the SPL, i.e. an open rock field, offering increased food and shelter opportunities, with sandy patches in between, facilitating the natural burrowing behaviour of plaice, forms the basis for the increased plaice abundances at the turbine scale. At the wind farm scale, beam trawl catches in between the turbines and in reference zones revealed significantly increased plaice abundances in one OWF, which suggests that wind farms can act as refuge areas for plaice, at least under specific conditions. Differences in environmental conditions, turbine foundation type, and surrounding fishing pressure may explain the equivocal findings between both OWFs, whereas low statistical power could have hampered the detection of general refuge effects. Next to the integration of different spatial scales (turbine/wind farm) within one study, longer-term monitoring and including extra life history parameters (e.g. length and sex ratio) might enhance the detectability of potential refuge effects.
... Moreover, most mandatory monitoring programmes mainly focus on the effects on the soft sediment habitat at a distance of ca. 200 m from the turbines, while attraction to the hard substrate habitat often takes place at a much smaller scale (Bergström et al. 2013;Wilber et al. 2018). ...
... The higher plaice abundances on the SPL compared to the surrounding sand seem to contradict the findings of other studies. Many wind farm monitoring programmes focus on a larger spatial scale and use trawling devices 200 m away from the turbines (Lindeboom et al. 2011;Stenberg et al. 2015;Wilber et al. 2018), which may mask small-scale attraction at the turbine scale (Bergström et al. 2013;Vandendriessche et al. 2015). However, studies that did look at small-scale attraction of plaice also found no effect or even demonstrated avoidance behavior in relation to the hard substrate (Krone et al. 2017; van Hal et al. 2017). ...
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The European Directive 2009/28/EC on the promotion of electricity produced from renewable energy sources in the internal electricity market, imposes a target figure for the contribution of the production of electricity from renewable energy sources upon each Member State. On 31 December 2019, Belgium submitted a National Energy and Climate Plan to the European Commission which envisions a target figure of 17.5% for the contribution of the production of electricity from renewable energy sources by 2030. Offshore wind farms in the Belgian part of the North Sea are expected to make an important contribution to achieve that goal. Within the Belgian part of the North Sea, a zone of 238 km² is reserved for the production of electricity from water, currents or wind. In that zone, eight wind farms are operational with a combined installed capacity of 2.26 MW. A second area for renewable energy of 285 km² is foreseen by the new Belgian marine spatial plan (2020-2026) with the government aiming for an installed capacity of 3.1 tot 3.5 GW in this zone. Prior to installing a wind farm, a developer must obtain a domain concession and an environmental permit. The environmental permit includes a number of terms and conditions intended to minimise and/or mitigate the impact of the project on the marine ecosystem. Furthermore, as required by law, the permit imposes a monitoring programme to assess the effects of the project onto the marine environment. Within the monitoring programme, the Royal Belgian Institute of Natural Sciences and its partners assess the extent of the anticipated impacts onto the marine ecosystem and aim at revealing the processes behind these impacts. The first objective is tackled through basic monitoring, focusing on the a posteriori, resultant impact quantification, while the second monitoring objective is covered by the targeted or process monitoring, focusing on the cause-effect relationships of a priori selected impacts. This report, targeting marine scientists, marine managers and policy makers, and offshore wind farm developers, presents an overview of the scientific findings of the Belgian offshore wind farm environmental monitoring programme (WinMon.BE), based on data collected up to and including 2020.
... Of the 867 findings identified, biological pressures correspond to the most-studied pressure category (63%) (Fig. 2a). From 16 pressure types (see Supplementary Table 4 for the full list), 10 pressures were assessed, the most frequent ones being those associated to biological disturbance [63][64][65] and noise input 66,67 (62% and 18% of the findings, respectively; Fig. 2b). Most findings associated to ecosystem elements were reported for species (87%, especially birds), ecosystem structure, functions, and processes (11%), and habitats (3%) (Fig. 2c). ...
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Offshore wind energy is widely regarded as one of the most credible sources for increasing renewable energy production towards a resilient and decarbonised energy supply. However, current expectations for the expansion of energy production from offshore wind may lead to significant environmental impacts. Assessing ecological risks to marine ecosystems from electricity production from wind is both timely and vital. It will support the adoption of management measures that minimize impacts and the environmental sustainability of the offshore wind energy sector.
... Fish representing broad trophic guilds forage on macroalgae and invertebrates living on artificial structures or zooplankton drifting near the structure; piscivorous fish also seek prey opportunities by foraging on smaller fish species, and top predators, such as large sharks can also be observed on artificial structures. For example, small gobies (Gobiusculus flavescens, Pomatoschistus minutus) (Wilhelmsson et al., 2006), as well as larger species, such as Atlantic cod (Gadus morhua) (Reubens et al., 2013) and flatfish (Wilber et al., 2018) can concentrate around wind turbines. Large predatory tiger sharks (Galeocerdo cuvier) and porbeagle sharks (Lamna nasus) have been detected near oil and gas platforms (Ajemian et al., 2020;Haugen & Papastamatiou, 2019). ...
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Humans use the coastal ocean and its resources as a source of food and energy, as well as for a variety of other purposes, including transportation and recreation. Over the past several decades, uses of the coastal ocean have been increasingly accompanied by the installation of artificial structures. These artificial structures come in different shapes and sizes, ranging from energy and aquaculture infrastructure that incidentally form habitat for marine organisms to artificial reefs that are often deployed intentionally to become habitat. Marine spatial planning has offered a robust framework for siting artificial structures to minimize conflicts with other uses and maximize societal and economic benefits with other intended uses of the seascape, but ecological criteria are seldom considered in the planning process. In contrast, artificial reefs are intentionally sunk to form structured habitat and provide a variety of ecological functions, yet ecological principles are not often incorporated into the siting and planning process. Instead, artificial reefs are sited largely to advance societal and economic benefits and minimize conflicts with other uses, such as shipping traffic, military use, or impacts to sensitive areas. We outline a framework to further incorporate ecological principles into artificial reef siting, design and construction, and evaluation that features place‐based and adaptive management coupled with tenets from experimental field ecology. This framework accounts for complexities of and interactions among ecological, societal, and economic criteria associated with artificial reefs to ensure they meet defined goals.
... Presence of fish has also been observed around turbine support structures and related devices [10][11][12][13], with aggregation of fish observed more frequently around the structure compared to reference sites. Generally, fish are attracted by anthropogenic structures, such as offshore wind farms [14][15][16][17][18], wave power foundations [19,20], and oil and gas platforms [21][22][23][24]. ...
Article
Understanding the risk of collision between tidal stream turbines and marine species is required for environmental impact assessment. Field observations are often limited by sensor capabilities. This study used a laboratory-scale water tank to monitor fine-scale fish behavior near a model of rotating turbine blades. Differences in behavior between three species were investigated: Oryzias latipes, Gnathopogon elongatus, and Rhodeus ocellatus ocellatus. Behavioral response under dark conditions was further investigated for Gnathopogon elongatus, as it showed active behavior near the turbine under bright conditions. 71% of fish actively avoided or swam away from the turbine during bright conditions. Under dark conditions, 92% avoided or swam away; fish approached less frequently and retreated sooner than in bright conditions. Alertness in dark conditions possibly increases due to the inability of fish to visually detect the blades; thus, dark conditions may not be directly linked to a higher collision risk. No striking events occurred which resulted in injury or mortality.
... Rhode Island Department of Environmental Management (RIDEM) conducts a biannual bottom trawl survey covering all RI state waters including areas around Block Island. The Block Island wind farm (BIWF) has a designated bottom trawl survey to evaluate impacts of the construction and operation of the wind farm (Lipsky et al., 2016;Wilber et al., 2018). The BIWF survey had data from 2013 to 2018. ...
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Within fisheries, stakeholders often have varying viewpoints regarding natural marine resources, and use different sets information to evaluate their condition. Evaluating a resource with different sets of information can lead to different conclusions. Windowpane flounder (Scophthalmus aquosus) are a managed finfish species in the northwest Atlantic whose regulations have the potential to limit harvest opportunities for target species. We analyzed commercial trip and catch information from video data to understand local densities of windowpane flounder in conjunction with fisheries independent surveys. Video monitoring data from three Rhode Island commercial fisher's vessels and fisheries independent trawl survey data were analyzed to understand the geographic distribution of the stock as well as overlap with temporary closed areas. Biomass data from the fisheries-dependent and fisheries-independent surveys were combined with a spatial-temporal model that accounted for differences in catchability among vessels and spatial autocorrelation. A separate analysis of estimated discard rates with observer data was also conducted to determine how the distribution of windowpane discards in Southern New England compared to the distribution of model predicted windowpane abundance. In agreement with the fishermen's observations, the temporary closed areas were not located where the highest densities of windowpane flounder occurred. The temporary closed areas, however, were located where the highest rates of discards occurred and thus where fishing had the greatest impact on the stock. The integration of verified fishery-dependent data with the scientific surveys has the potential to create a single set of information that is trusted by all user groups.
... In this instance, similar to its DIDSON predecessor, the ARIS 3000 imaging sonar may be applied to various habitats subject to low visibility conditions including dynamic estuarine environments, mangrove habitats, fjords, coastal lagoons, saltmarshes and other turbid riverine and coastal environments subject to agricultural run-off where traditional camera techniques are limited (Maxwell and Gove, 2007;Shahrestani et al., 2017). This tool may also be applied to sensitive habitats or seabed infrastructure (Wilber et al., 2018) where extractive techniques are restricted as well as to target species which are known to be difficult to catch using traditional sampling methods (e.g. netting). ...
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Assessment and monitoring of marine biodiversity, including fish populations, is essential for evidence-based conservation management of coastal marine resources. The effectiveness of monitoring techniques for stock assessment varies with sea conditions. In dynamic marine environments with high turbidity, such as those found in estuaries, mangroves, coastal straits, fjords, and bays, traditional assessment methods include the use of destructive techniques such as trawling. Hydroacoustic sampling techniques overcome such restrictions, equipment such as echosounders have commonly been used for biodiversity assessments including fish community structure, biomass, behaviour, and dynamics studies. However, hydroacoustic methods have been shown to be less reliable for species identification. The high frequency Adaptive Resolution Imaging Sonar (ARIS) is widely used for underwater object detection and imaging. Our study investigated the suitability of ARIS 3000 for the species identification of North-East Atlantic marine species using experimental aquarium studies, field surveys and multi investigator assessments. Aquaria results showed that 82 % of species were detected by observers, of which five were identified correctly identified consistently. The remaining four species were identified correctly <67 % of the time. During field surveys, a 150 % higher confidence in identification was given to more morphologically distinct groups such as elasmobranchs. Whilst our results highlight the suitability of the ARIS for accurate and repeatable identification of some of the model species used in this study, we have also shown that factors such as size and morphological traits limit the accuracy of identification for all species. We suggest that monitoring techniques combine the use of ARIS sonars alongside other sampling tools for assessing motile faunal communities.
... This consideration should include anticipated changes to the benthic habitats, potential for invasive species, vertical and horizontal movement of water, sediment suspension, and water column changes. Oceanography | December 2020 25 environment during pile driving (Amaral et al., 2019), sediment suspension and deposition during cable laying (Elliott et al., 2017), and establishment of the post-construction benthic community (LaFrance Bartley et al. 2019), as well as effects on the flatfish community during construction (Wilber et al. 2018). Lastly and perhaps most importantly, with few unambiguous findings from these studies, the BIWF experience demonstrates the ongoing challenges in attaining a clear understanding of ecological effects. ...
Article
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Offshore renewable energy development is being sought by US coastal states to meet their renewable energy goals. Numerous offshore wind development projects are being proposed along the Atlantic coast, and additional areas are being explored in the Pacific. Commercial-scale offshore wind will share the seas with marine fisheries that provide immense economic, recreational, and cultural value as well as local food security. An acceleration in the number of proposed wind projects combined with a lack of clarity on how fishing activities are to be incorporated into the planning process has created numerous challenges for the fishing community and for fisheries managers. This paper explores ecological, human, and fishery management interactions with wind development, focusing on the Northeast US Shelf Large Marine Ecosystem. With an emphasis on a regional perspective, we identify key challenges to and opportunities for the goal of coexistence of offshore wind energy development and fishing activities, and we make several recommendations toward achieving this goal. Although the challenges to achieving coexistence of these two industries are significant, we argue that they are surmountable and can be overcome through a combination of collaboration, regional approaches, and innovation.
... In the U.S. Atlantic Outer Continental Shelf (OCS), over 5,492 km 2 is presently under lease agreement with the Bureau of Ocean Energy Management (BOEM) for development of commercial-scale offshore wind energy facilities and an additional 12,976 km 2 is in the planning stages for potential leases (BOEM 2019). The only offshore wind energy facility currently operating in North America is a 5-turbine, 30-megawatt (MW) demonstration-scale facility near Block Island, Rhode Island, USA, that started operations in 2016 (Wilber et al. 2018). The potential adverse effects of offshore wind energy developments on avian species include collision mortality, behavioral changes near turbines in response to visual stimuli, and impacts from physical alteration of habitat in response to construction of turbines and other infrastructure . ...
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In advance of large-scale development of offshore wind energy facilities throughout the U.S. Atlantic Outer Continental Shelf (OCS), information on the migratory ecology and routes of federally threatened Atlantic Coast Piping Plovers (Charadrius melodus melodus) is needed to conduct risk assessments pursuant to the Endangered Species Act. We tagged adult Piping Plovers (n = 150) with digitally coded VHF transmitters at 2 breeding areas within the southern New England region of the U.S. Atlantic coast from 2015 to 2017. We tracked their migratory departure flights using a regional automated telemetry network (n = 30 stations) extending across a portion of the U.S. Atlantic Bight region, a section of the U.S. Atlantic coast, and adjacent waters of the Atlantic Ocean extending from Cape Cod, Massachusetts, to Cape Hatteras, North Carolina. Most adults departed within a 10-day window from July 19 to July 29, migrated nocturnally, and over 75% of individuals departed within 3 hr of local sunset on evenings with supportive winds. Piping Plovers migrated offshore directly across the mid-Atlantic Bight, from breeding areas in southern New England to stopover sites spanning from New York to North Carolina, USA, over 800 km away. During offshore migratory flights, Piping Plovers flew at estimated mean speeds of 42 km hr−1 and altitudes of 288 m (range of model uncertainty: 36–1,031 m). This study provides new information on the timing, weather conditions, routes, and altitudes of Piping Plovers during fall migration. This information can be used in estimations of collision risk that could potentially result from the construction of offshore wind turbines under consideration across large areas of the U.S. Atlantic OCS.
... In relation to OWF, 19% of the studies included data on the impact on soft-bottom species. At Block Island Wind Farm, off Rhode Island in US, a study of seven flatfish species revealed no negative impacts [78]. On the contrary, Lindeboom et al. [65] reported a significant decrease in the soft-bottom species lesser weever (Echiichthys vipera) 2 years after construction of a Dutch OWF. ...
Article
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As the development of large-scale offshore wind farms (OWFs) amplifies due to technological progress and a growing demand for renewable energy, associated footprints on the seabed are becoming increasingly common within soft-bottom environments. A large part of the footprint is the scour protection, often consisting of rocks that are positioned on the seabed to prevent erosion. As such, scour protection may resemble a marine rocky reef and could have important ecosystem functions. While acknowledging that OWFs disrupt the marine environment, the aim of this systematic review was to examine the effects of scour protection on fish assemblages, relate them to the effects of designated artificial reefs (ARs) and, ultimately, reveal how future scour protection may be tailored to support abundance and diversity of marine species. The results revealed frequent increases in abundances of species associated with hard substrata after the establishment of artificial structures (i.e. both OWFs and ARs) in the marine environment. Literature indicated that scour protection meets the requirements to function as an AR, often providing shelter, nursery, reproduction, and/or feeding opportunities. Using knowledge from AR models, this review suggests methodology for ecological improvements of future scour protections, aiming towards a more successful integration into the marine environment.
... This is evidenced by several studies that have found significant differences between control and prospective impact locations during baseline surveys (e.g. Wilber et al., 2018), significant and unexplainable changes at the control location over time (e.g. Atalah et al., 2012;Degraer et al., 2013), and changes at control locations that differed from the changes recorded at the wind farm location (e.g. ...
Article
Offshore wind farms often co-occur with biodiverse marine ecosystems with high ecological, economic, and cultural value. Yet there are many uncertainties about how wind farms affect marine organisms and their environment. The before–after–control–impact (BACI) design, an approach that compares an impact location with an unaffected control both before and after the intervention, is the most common method used to study how offshore wind farms affect finfish. Unfortunately, this design has several methodological limitations that undermine its ability to detect effects in these studies. An alternative approach, the before–after-gradient (BAG) design, would sample along a gradient with increasing distance from the turbines both before and after the intervention, and could overcome many of the limitations of BACI. The BAG design would eliminate the difficult task of finding a suitable control, allow for the assessment of the spatial scale and extent of wind farm effects, and improve statistical power by incorporating distance as an independent variable in analytical models rather than relegating it to the error term. This article explores the strengths and weaknesses of the BACI and BAG designs in the context of offshore wind development and suggests an approach to incorporating the BAG design into existing fisheries surveys and a regional monitoring framework.
... At Block Island Wind Farm, off Rhode Island (USA), a study of seven flatfish species found neither a reef effect nor negative impacts (i.e. overall neutral effect) of offshore installations (Wilber et al., 2018). Any effects of retained offshore infrastructure on surrounding soft-sediment ecosystems may be minimal on a regional scale, given the small amount of affected soft-sediment habitat relative to natural soft-sediment habitats in the North Sea (Stenberg et al., 2015;Hyder et al., 2017). ...
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As decommissioning of oil and gas (O&G) installations intensifies in the North Sea, and worldwide, debate rages regarding the fate of these novel habitats and their associated biota-a debate that has important implications for future decommissioning of offshore wind farms (OWFs). Calls to relax complete removal requirements in some circumstances and allow part of an O&G installation to be left in the marine environment are increasing. Yet knowledge regarding the biological communities that develop on these structures and their ecological role in the North Sea is currently insufficient to inform such decommissioning decisions. To focus debate regarding decommissioning policy and guide ecological research, we review environmental policy objectives in the region, summarize existing knowledge regarding ecological aspects of decommissioning for both O&G and OWF installations, and identify approaches to address knowledge gaps through science-industry collaboration. We find that in some cases complete removal will conflict with other policies regarding protection and restoration of reefs, as well as the conservation of species within the region. Key ecological considerations that are rarely considered during decommissioning decisions are: (i) provision of reef habitat, (ii) productivity of offshore ecosystems, (iii) enhancement of biodiversity, (iv) protection of the seabed from trawling, and (v) enhancement of connectivity. Knowledge gaps within these areas will best be addressed using industry infrastructure and vessels for scientific investigations, re-analysis of historical data held by industry, scientific training of industry personnel, joint research funding opportunities, and trial decommissioning projects.
... Eggleston et al. (2018) evidenced the impact of bottom trawling on the diet of 3 of the 4 studied flatfish species in the North Sea. Wilber et al. (2018) focused on the impact of wind farms on 7 flatfish species before and during their construction, and then during operation time, without evidencing an attraction effect ...
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... Lindeboom et al. (2011) found that seals stayed away from an offshore wind farm during pile driving. Two studies (Lindeboom et al., 2011;Wilber et al., 2018) determined that although drilling for offshore wind farm turbines was audible in reference areas, it did not seem to have a major impact on fish abundance. ...
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Offshore wind is gaining momentum in the United States as a viable source for meeting domestic energy needs. Although offshore wind farms have been developed in Europe and Asia, the Block Island Wind Farm (BIWF) is the first offshore wind farm built in North America. To improve marine resource management, it is critical to understand the impacts of the wind farm on marine resource users in context. Little is known about the impacts of offshore wind farms on marine resource users in the United States. This study investigates recreational and commercial fishers' perceptions of the impacts of the BIWF on the local marine ecosystem. Semi-structured interviews were conducted with 25 fishers, mostly based out of Block Island or Point Judith, Rhode Island (US), in the summer and fall of 2017. During the interviews, fishers were asked about their perceptions of changes in the marine ecology of the wind farm area during and after the offshore wind turbines were constructed, and how their activities in the area have changed since the wind farm was installed. Results indicate that there were perceived impacts of the BIWF on the local ecosystem and the behavior of the marine resource users. For some recreational fishers, the wind farm functioned as a destination or target and served as an artificial reef for spearfishing. For some commercial fishers, the increase in recreational fishing due to the establishment of the BIWF crowded out commercial fishers in these areas. As the offshore wind farm industry expands within US waters, findings from this study and others like it can provide valuable insights on the potential impacts of these wind farms on marine resource users.
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This is the first study to document quantitatively that Gulf of Maine (GOM) Winter Flounder spawn offshore. Three sites (southern Jeffreys Ledge, Bigear [an area southwest of Tillies Bank], and a portion of Stellwagen Bank National Marine Sanctuary) were sampled during spring 2016 to determine if Winter Flounder are spawning in non-coastal, deep waters in the southern GOM. A total of 1,384 Winter Flounder were caught by trawl, measured, sexed, and assessed for reproductive stage during the peak spawning season (March – May). These fish showed clear signs that spawning was occurring either at or very nearby all three sites surveyed. In all sites, a shift from pre-spawning to post-spawning females occurred. Running ripe females were caught at both Jeffreys Ledge and Stellwagen Bank on multiple occasions, and ripe and recently spawned females were caught at Bigear. Given that these sites are >15 km from the coast, it is not energetically likely that fish in such advanced reproductive condition are migrating to shore to spawn. Essential Fish Habitat (EFH) for GOM Winter Flounder is categorized as waters ≤5 m. This study clearly shows that this depth range is incomplete and thus inaccurate for southern GOM Winter Flounder. While it is irrefutable that GOM estuaries and shallow bays are important nursery grounds for juvenile Winter Flounder and post-spawning feeding grounds for adults, the current GOM EFH designation warrants reclassification. Received 05 May 2017 accepted 02 Aug 2017 revised 01 Aug 2017
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Effects of constructing the DanTysk offshore wind farm (German Bight, 80 turbines, 6 m diameter foundations) were studied by passive acoustic monitoring of pile-driving noise and harbour porpoise Phocoena phocoena echolocation. An acoustic deterrence device (seal scarer) was used to protect porpoises from hearing loss and bubble curtains were used to attenuate the pile-driving noise. Porpoise occurrence, quantified by echolocation signals, decreased when the seal scarer was engaged, during pile driving and up to 5 h after pile driving stopped. This effect extended out to 12 km, less than the 18-25 km reported from other pile drivings performed without bubble curtains. The bubble curtains thus effectively reduced the temporary habitat loss and risk of hearing loss. The 2 bubble curtains each attenuated the noise by between 7 and 10 dB, when used separately, and 12 dB when used together. Attenuation was most pronounced above 1 kHz, where the pile-driving noise at larger distances was comparable to or lower than ambient noise. This suggests that noise regulation should be based on frequency-weighted sound levels in addition to broadband levels, to assure that mitigation measures are effective in reducing impact on animals and not only in fulfilling legal requirements. The strong reaction to the seal scarer raises concern that it may surpass the reactions to the pile-driving noise itself, when operating with bubble curtains, and calls for a re-evaluation of the specifications of seal scarer sounds.
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Extensive development and construction in marine and coastal systems is driving a phenomenon known as “ocean sprawl”. Ocean sprawl removes or transforms marine habitats through the addition of artificial structures and some of the most significant impacts are occurring in sedimentary environments. Marine sediments have substantial social, ecological, and economic value, as they are rich in biodiversity, crucial to fisheries productivity, and major sites of nutrient transformation. Yet the impact of ocean sprawl on sedimentary environments has largely been ignored. Here we review current knowledge of the impacts to sedimentary ecosystems arising from artificial structures.
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The growing number of artificial structures in estuarine, coastal and marine environments is causing “ocean sprawl”. Artificial structures do not only modify marine and coastal ecosystems at the sites of their placement, but may also produce larger-scale impacts through their alteration of ecological connectivity - the movement of organisms, materials and energy between habitat units within seascapes. Despite the growing awareness of the capacity of ocean sprawl to influence ecological connectivity, we lack a comprehensive understanding of how artificial structures modify ecological connectivity in near- and off-shore environments, and when and where their effects on connectivity are greatest. We review the mechanisms by which ocean sprawl may modify ecological connectivity, including trophic connectivity associated with the flow of nutrients and resources. We also review demonstrated, inferred and likely ecological impacts of such changes to connectivity, at scales from genes to ecosystems, and potential strategies of management for mitigating these effects. Ocean sprawl may alter connectivity by: (1) creating barriers to the movement of some organisms and resources - by adding physical barriers or by modifying and fragmenting habitats; (2) introducing new structural material that acts as a conduit for the movement of other organisms or resources across the landscape; and (3) altering trophic connectivity. Changes to connectivity may, in turn, influence the genetic structure and size of populations, the distribution of species, and community structure and ecological functioning. Two main approaches to the assessment of ecological connectivity have been taken: (1) measurement of structural connectivity - the configuration of the landscape and habitat patches and their dynamics; and (2) measurement of functional connectivity - the response of organisms or particles to the landscape. Our review reveals the paucity of studies directly addressing the effects of artificial structures on ecological connectivity in the marine environment, particularly at large spatial and temporal scales. With the ongoing development of estuarine and marine environments, there is a pressing need for additional studies that quantify the effects of ocean sprawl on ecological connectivity. Understanding the mechanisms by which structures modify connectivity is essential if marine spatial planning and eco-engineering are to be effectively utilised to minimise impacts.
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Long-term effects of the Horns Rev 1 offshore wind farm (OWF) on fish abundance, diversity and spatial distribution were studied. This OWF is situated on the Horns Reef sand bank in the North Sea. Surveys were conducted in September 2001, before the OWF was established in 2002, and again in September 2009, 7 yr post-establishment. The sampling surveys used a multimesh- size gillnet. The 3 most abundant species in the surveys were whiting Merlangius merlangus, dab Limanda limanda and sandeels Ammodytidae spp. Overall fish abundance increased slightly in the area where the OWF was established but declined in the control area 6 km away. None of the key fish species or functional fish groups showed signs of negative long-term effects due to the OWF. Whiting and the fish group associated with rocky habitats showed different distributions relative to the distance to the artificial reef structures introduced by the turbines. Rocky habitat fishes were most abundant close to the turbines while whiting was most abundant away from them. Species diversity was significantly higher close to the turbines. Overall, these results indicate that the artificial reef structures were large enough to attract fish species with a preference for rocky habitats, but not large enough to have adverse negative effects on species inhabiting the original sand bottom between the turbines.
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The rapid increase in offshore wind energy worldwide has raised concern about its potential risks to marine biodiversity due to habitat alteration, disturbance from noise and electromagnetic fields. This study presents results of surveillance studies performed at the Lillgrund wind farm in Sweden to investigate the integrated effects of these factors on the abundance and distribution patterns of benthic fish communities. The studies revealed no large-scale effects on fish diversity and abundance after establishment of the wind farm when compared to the development in 2 reference areas. Changes in some species and in community composition were observed over time but occurred in parallel in at least one reference area, indicating that fish communities in the wind farm area were mainly driven by the same environmental factors as those in surrounding areas. However, changes at smaller spatial scales were evident. Increased densities of all studied piscivores (cod, eel, shorthorn sculpin), as well as the reef-associated goldsinny wrasse, were observed close to the foundations in the first years of operation. The increase was probably attributed mainly to local changes in distribution rather than to immigration or increased local productivity. Simultaneously, weak or no aggregation of black goby, eelpout and shore crab, all potentially reef-associated but also prey species of the studied piscivores, was observed, which may indicate enhanced top-down control near the foundations.
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With the construction of wind farms, new hard substrates are introduced in the marine environment. Between the turbine rows and around the wind farms, however, the soft sediments remain. The inhabiting fauna of these sandy sediments may be influenced by the presence of the turbines and the absence of fisheries in the wind farms. These effects were investigated for epibenthos, demersal fish, and benthopelagic fish in the Thorntonbank and Bligh Bank wind farms in the Belgian part of the North Sea. Inside the wind farms, several local and temporal effects were detected, including both temporary construction effects (e.g., decreased densities of dab, ophiuroids and dragonets) as refugium effects (e.g., the presence of relatively large plaice). At the wind farm edges, only few temporary effects were noted, but real edge effects due to changes in fisheries intensity or ‘spillover’ from the wind farms could not be shown. The observed effects were not consistent between bothwind farms, which is not surprising, given the differences in epibenthos and fish communities, sandbank topography, fishing pressure, development stage of the wind farms, and the used foundation types. This inconsistency stresses the importance to replicate monitoring activities across wind farms and along the identified gradients.
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Offshore wind power provides a valuable source of renewable energy that can help reduce carbon emissions. Technological advances are allowing higher capacity turbines to be installed and in deeper water, but there is still much that is unknown about the effects on the environment. Here we describe the lessons learned based on the recent literature and our experience with assessing impacts of offshore wind developments on marine mammals and seabirds, and make recommendations for future monitoring and assessment as interest in offshore wind energy grows around the world. The four key lessons learned that we discuss are: 1) Identifying the area over which biological effects may occur to inform baseline data collection and determining the connectivity between key populations and proposed wind energy sites, 2) The need to put impacts into a population level context to determine whether they are biologically significant, 3) Measuring responses to wind farm construction and operation to determine disturbance effects and avoidance responses, and 4) Learn from other industries to inform risk assessments and the effectiveness of mitigation measures. As the number and size of offshore wind developments increases, there will be a growing need to consider the population level consequences and cumulative impacts of these activities on marine species. Strategically targeted data collection and modeling aimed at answering questions for the consenting process will also allow regulators to make decisions based on the best available information, and achieve a balance between climate change targets and environmental legislation.
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Three theories of habitat use proposed for marine fishes-the constant density model, the proportional density model, and the basin model-make contrasting predictions of how the geographical range, local density, and fitness change as population size changes. We tested model predictions with survey data on yellowtail flounder Limanda ferruginea from the Georges Bank region, where abundance changed by a factor of 4 over a decade. Surveys took place in spring and fall, and data on individual length, mass, sex, and reproductive status were available. Analysis of spatial pattern revealed that the overall area occupied by flounder increased by a factor of 2 when abundance was high, and local density increased predominantly in high quality habitat that had been closed to commercial fishing. Condition, which served as a proxy for fitness, was lower in females when abundance was high. Geospatial analysis revealed mesoscale variability in condition, over 10s to > 100 km, except in the spring season during low abundance periods. Spatial autocorrelation explained as much as 25% of the variability in condition, indicating that site dependence was a factor in explaining the spatial distribution that we observed. These results are most supportive of both the constant density model and the basin model. This approach detected an important population center for yellowtail flounder and determined its extent using only measures of abundance, location, and condition of individual fish, data commonly collected during routine fishery assessment surveys. Here we demonstrate that analyses linking population responses to variation in such measures at local spatial scales can have significant implications for identifying areas of important fish habitat and suggest greater use of geospatial approaches in conservation and management of exploited species.
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The current knowledge on detection of, and reaction to, sound by fish is reviewed, with special emphasis on underwater noise from offshore wind farms. The detection distance to wind farms for 3 species of fish representing various hearing capabilities varies between 0.4 and 25 km at wind speeds of 8 to 13 m s -1. The detection distance depends on the size and number of windmills, the hearing abilities of the fish, background noise level, wind speed, water depth and type of sea bottom. The noise from windmills may decrease the effective range for sound communication of fish; however, it is not known to what extent this decrease affects the behaviour and fitness of fish. Windmill noise does not have any destructive effects upon the hearing abilities of fish, even within distances of a few metres. It is estimated that fish are consistently scared away from windmills only at ranges shorter than about 4 m, and only at high wind speeds (higher than 13 m s -1). Thus, the acoustic impact of windmills on fish is restricted to masking communication and orientation signals rather than causing physiological damage or consistent avoidance reactions. These conclusions must be viewed with great caution, however, as the existing data are prone to large uncertainties. Further studies on more detailed measurements of the sound-field and of fish behaviour around windmills are needed.
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Rapid colonization, high fish densities, and high catch rates at artificial reefs have been used as evidence for habitat-limitation and increased production of reef fishes. An alternative hypothesis is that artificial reefs attract fishes due to behavioral preferences but do not increase reef fish production or abundance. Reviewed literature reveals that except in one case evidence for increased production is mostly anecdotal and inadequate. Attraction and/or production by a particular artificial reef is predicted to depend on the species and individual ages (size) of reef fish, and on reef location. Factors predicted to be important are natural reef availability, mechanisms of natural population limitation, fishery exploitation pressure, life history dependency on reefs, and species-specific and age-specific behavioral characteristics. Increased production is most likely at locations isolated from natural reefs, and for habitat-limited, demersal, philopatric, territorial, and obligatory reef species. Attraction should be more important in locations with abundant natural reef habitat; where exploitation rates are high; and for recruitment-limited, pelagic, highly mobile, partially reef-dependent, and opportunistic reef species. Artificial reefs are unlikely to benefit heavily exploited or overfished populations without other management actions.
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We implanted individually coded acoustic transmitters into 40 adult winter flounder Pseudopleuronectes americanus (mean total length = 320 mm; range = 240–423 mm) and monitored them by use of passive acoustic telemetry from September 2007 to April 2009 to classify spatial and temporal movement patterns and quantify residency in Shinnecock Bay, eastern Long Island, New York. Overall, 94,250 valid detections were received. Winter flounder remained inshore, and 89% of the total detections occurred between May and October when bottom water temperature exceeded 15°C. Residency in Shinnecock Bay was dependent on time of release and varied greatly from a few weeks to more than 6 months; total presence (number of days on which individual fish were detected within the bay) averaged 22.0 d (range = 1–132 d). Tracked winter flounder were classified as exhibiting three movement patterns: (1) inner bay movements (short term versus long term), (2) dispersal to offshore waters, and (3) connectivity to other inshore areas. The first two patterns were consistent with historical notions of spatially overlapping resident and migratory individuals, whereas fish that displayed the third pattern may have exhibited a larger home range. These results provide insight into winter flounder movements, residency, and stock structure in a coastal bay of Long Island and provide important information for management. The interaction of exploitation and divergent migration behaviors may be a factor contributing to the winter flounder's decline in Long Island bays; however, more work will be required to obtain a full understanding of the spatial behavior and stock structure of this species.
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The number of offshore wind farms is increasing rapidly, leading to questions about the environmental impact of such farms. In the Netherlands, an extensive monitoring programme is being executed at the first offshore wind farm (Offshore Windfarm Egmond aan Zee, OWEZ). This letter compiles the short-term (two years) results on a large number of faunal groups obtained so far. Impacts were expected from the new hard substratum, the moving rotor blades, possible underwater noise and the exclusion of fisheries. The results indicate no short-term effects on the benthos in the sandy area between the generators, while the new hard substratum of the monopiles and the scouring protection led to the establishment of new species and new fauna communities. Bivalve recruitment was not impacted by the OWEZ wind farm. Species composition of recruits in OWEZ and the surrounding reference areas is correlated with mud content of the sediment and water depth irrespective the presence of OWEZ. Recruit abundances in OWEZ were correlated with mud content, most likely to be attributed not to the presence of the farm but to the absence of fisheries. The fish community was highly dynamic both in time and space. So far, only minor effects upon fish assemblages especially near the monopiles have been observed. Some fish species, such as cod, seem to find shelter inside the farm. More porpoise clicks were recorded inside the farm than in the reference areas outside the farm. Several bird species seem to avoid the park while others are indifferent or are even attracted. The effects of the wind farm on a highly variable ecosystem are described. Overall, the OWEZ wind farm acts as a new type of habitat with a higher biodiversity of benthic organisms, a possibly increased use of the area by the benthos, fish, marine mammals and some bird species and a decreased use by several other bird species.
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Sediment profile imaging (SPI) technology has been used in some form since 1969 to investigate the structure and appearance of near-surface aquatic sediments. The recognition of patterns in images and their relationship to seafloor processes mediated by biological, physical and chemical interactions was pioneered by academic scientists interested in sedimentary structures and evidence of biological communities in the geological record. The application of SPI technology to environmental assessment coincided with the development and testing of a robust theory of marine benthic community responses to disturbance in fine sedimentary habitats. The patterns visible in the images of seafloor sediments were related to processes associated with the recolonization of disturbed fine sediments through manipulation experiments and field observations. Association of these patterns with stages in the recovery of disturbed habitats provided the basis for SPI as a tool for environmental assessment and monitoring surveys. After almost 40 years of application of SPI technology to environmental assessment and monitoring, we are in a position to summarize the strengths and weaknesses of this technology. This review describes the history of instrument development and image interpretation, discusses the technical limitations and advantages of the method, summarizes the range of applications of SPI technology, and considers possible future directions for the technology, supporting theory, and application.
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Winter flounder ( Pseudopleuronectes americanus ) come inshore during the late winter and early spring to lay their eggs in shallow bays and estuaries along the coast. Unlike most fish eggs, which are buoyant, these eggs are demersal and sink to the seafloor. This makes them vulnerable to burial from various types of natural and human caused disturbances (e.g., storms, mobile fishing gear, maintenance dredging). Our objective was to map spawning areas in two harbors and search for generalities among these sites that would allow us to predict where winter flounder might spawn in other areas. This would allow managers to avoid permitting activities for those times and locations where winter flounder spawn.We used a modified demersal plankton net (a benthic sled) to collect winter flounder eggs in New Haven and Milford harbors and map their distributions. Most of the eggs were collected at the end of March, when water temperatures were 4-6<sup>°</sup> C. This could vary from year to year depending on temperature. The distributions of eggs were not correlated with sediment type or depth but were related to the prevailing tidal currents in the area sampled. Since the eggs are present in low-current depositional areas, they are vulnerable to burial. Our observations suggest that winter flounder either do not deposit eggs in high current areas, or if eggs are deposited there, they are swept away. Since early stage embryos (morula, blastula, gastrula) were found in low current areas, it seems unlikely that they were transported there from some other location. These findings have important management implications because any activities (dredging, building breakwaters, installing docks) near spawning areas could have adverse effects if they change the prevailing currents in the area.
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With the large scale developments of offshore windpower the number of underwater electric cables is increasing with various technologies applied. A wind farm is associated with different types of cables used for intraturbine, array-to-transformer, and transformer-to-shore transmissions. As the electric currents in submarine cables induce electromagnetic fields there is a concern of how they may influence fishes. Studies have shown that there are fish species that are magneto-sensitive using geomagnetic field information for the purpose of orientation. This implies that if the geomagnetic field is locally altered it could influence spatial patterns in fish. There are also physiological aspects to consider, especially for species that are less inclined to move as the exposure could be persistent in a particular area. Even though studies have shown that magnetic fields could affect fish, there is at present limited evidence that fish are influenced by the electromagnetic fields that underwater cables from windmills generate. Studies on European eel in the Baltic Sea have indicated some minor effects. In this article we give an overview on the type of submarine cables that are used for electric transmissions in the sea. We also describe the character of the magnetic fields they induce. The effects of magnetic fields on fish are reviewed and how this may relate to the cables used for offshore wind power is discussed.
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The number of offshore wind farms (OWF) is increasing to meet the demands for renewable energy. The piles and hard substrate surrounding these piles creates new habitat for species with preference to hard substrates. We studied the impact of this hard substrate on the fish community in a Dutch OWF in the sandy southern North Sea, which had been in operation for five years. Multi-mesh gillnets were placed near the OWF structures on the hard substrate protection revetments and on the sandy bottom in the middle of the farm. The catches indicated attraction of cod, pouting, bullrout and edible and velvet crab, while attraction to the sandy habitat was shown for flatfish and whiting. Further, two species previously not caught in this area, goldsinny wrasse and grey trigger fish, were caught on the hard substrate. In addition a Dual-Frequency Identification Sonar (DIDSON) was used to record transects through the farm to observe individual fish in the water column throughout the farm and very near the OWF structures. High abundances of fish near the structure were observed during some days, while during other days equal distribution of fish in the area was observed. The area around the structures is thus only used temporarily for shelter or feeding. The DIDSON also allowed looking at the aggregation level of the fish. Seasonally the aggregation level differed most likely due to different species occurring in the area. In April, most fish were aggregated in schools, while in summer most observations were individual fish or loose aggregations. The wind farm structures had limited effect on the aggregation level compared to season or weather conditions.
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Generalized additive models were used to investigate fine-scale spatial variation in female maturity across the three United States' winter flounder (Pseudopleuronectes americanus) stocks. The effect of temperature on maturity was also investigated. Maturity models explicitly incorporating spatial structure performed better than "traditional" methods incorporating spatial effects by aggregating data according to predefined stock boundaries. Models including temperature explained more of the variability in maturity than those based only on fish size or age but did not improve fit over models incorporating spatial structure. Based on the size-and age-at-maturity estimates from the spatially explicit models, distinct subareas were objectively identified using a spatially constrained clustering algorithm. The results suggested greater variation in size-and age-at-maturity within than between existing stock areas. The approach outlined here provides a method for identifying areas with different vital rates without the need to presume subjective boundaries.
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The abundance, biomass, diversity, and species composition of the demersal fish and invertebrate community in Rhode Island Sound and Block Island Sound, an area identified for offshore renewable energy development, were evaluated for spatial and seasonal structure. We conducted 58 otter trawls and 51 beam trawls in the spring, summer and fall of 2009–2012, and incorporated additional data from 88 otter trawls conducted by the Northeast Area Monitoring and Assessment Program. We used regionally-grouped abundance, biomass, diversity, and size spectra to assess spatial patterns in the aggregate fish community, and hierarchical cluster analysis to evaluate trends in species assemblages. Our analyses revealed coherent gradients in fish community biomass, diversity and species composition extending from inshore to offshore waters, as well as patterns related to the differing bathymetry of Rhode Island and Block Island Sounds. The fish communities around Block Island and Cox's Ledge are particularly diverse, suggesting that the proximity of hard bottom habitat may be important in structuring fish communities in this area. Species assemblages in Rhode Island and Block Island Sounds are characterized by a combination of piscivores (silver hake, summer flounder, spiny dogfish), benthivores (American lobster, black sea bass, Leucoraja sp. skates, scup) and planktivores (sea scallop), and exhibit geographic patterns that are persistent from year to year, yet variable by season. Such distributions reflect the cross-shelf migration of fish and invertebrate species in the spring and fall, highlighting the importance of considering seasonal fish behavior when planning construction schedules for offshore development projects. The fine spatial scale (10 s of kms) of this research makes it especially valuable for local marine spatial planning efforts by identifying local-scale patterns in fish community structure that will enable future assessment of the ecological impacts of offshore development. As such, this knowledge of the spatial and temporal structure of the demersal fish community in Rhode Island and Block Island Sounds will help to guide the placement of offshore structures so as to preserve the ecological and economic value of the area.
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Windowpanes Scophthalmus aquosus were collected during demersal trawl surveys in Northumberland Strait in the southern Gulf of St. Lawrence, Canada, during July and August 2001–2012. Abundance indices showed relatively little variation between years. Windowpanes were widely distributed in the strait, with 95% of the population occurring in water 9.5°C. The Windowpanes collected were small, all Crangon septemspinosa, followed by mysids and (for fish >20 cm) sand lances Ammodytes spp. and juvenile Atlantic Herring Harengus harengus. Small (Mysis spp.; those consumed on mud bottom were mainly Neomysis americana. Cannibalism was low, consisting of two individuals Received May 23, 2013; accepted November 22, 2013
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Atlantic cod (Gadus morhua) is a commercially important fish species suffering from overexploitation in the North-East Atlantic. In recent years, their natural environment is being intensively altered by the construction of offshore wind farms in many coastal areas. These constructions form artificial reefs influencing local biodiversity and ecosystem functioning. It has been demonstrated that Atlantic cod is present in the vicinity of these constructions. However, empirical data concerning the diel activity and feeding behaviour of Atlantic cod in the vicinity of these artificial reefs is lacking. Atlantic cod has a flexible diel activity cycle linked to spatio-temporal variations in food availability and predation risk. In this study we integrated acoustic telemetry with stomach content analysis to quantify diel activity and evaluate diel feeding patterns at a windmill artificial reef (WAR) in the Belgian part of the North Sea. Atlantic cod exhibited crepuscular movements related to feeding activity; a 12 h cycle was found and the highest catch rates and stomach fullness were recorded close to sunset and sunrise. It is suggested that the observed diel movement pattern is related to the prey species community and to predation pressure. Foraging at low ambient light levels (i.e. at dusk and dawn) probably causes a trade-off between foraging success and reducing predation pressure. Fish did not leave the area in-between feeding periods. Hence other benefits (i.e. shelter against currents and predators) besides food availability stimulate the aggregation behaviour at the WARs.
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Winter flounder habitat use in New York/New Jersey Harbor was examined through a long-term (2002–2010) bottom trawl sampling program (Aquatic Biological Survey) in which 5234 winter flounder were captured in 2069 samples collected at approximately 26 stations throughout the harbor. Interannual variability in catch-per-unit-effort (CPUE) primarily was attributable to fluctuations in Year-1 juvenile CPUE, which was positively correlated with total annual egg abundances from the previous year. Adult male CPUE during the spawning season was positively correlated with total egg abundances of the same year, whereas adult female CPUE was unrelated to annual egg abundances in the harbor. Annual variation in adult male densities in the harbor during the spawning season reflects the intensity of estuarine spawning activity, whereas adult female densities may include non-reproductive, foraging individuals. Seasonal fluctuations in condition indices reflected energy use during the spawning season, with relatively high condition in January, reduced levels in March and April, and elevated condition again in May. Adult CPUE peaked in April, coincident with the critical feeding period that follows spawning. Mean April water temperatures were positively correlated with egg abundances the following year and Year-1 juvenile CPUE two years later. A similar correlation between April temperatures and Year-1 juvenile abundances two years later was demonstrated using published data for winter flounder collected in Niantic Bay, CT. Higher April water temperatures may enhance benthic secondary production during the critical feeding period, and thus increase prey availability for foraging adults that need to restore energy reserves in order to reproduce the following year. A direct examination of benthic secondary production and variation in winter flounder estuarine foraging and subsequent spawning activity is needed to more fully understand this relationship.
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Surf zone fishes were captured by beach seine over the late summer and early fall of 5 yr (1995 to 1999), spanning pre-, during, and post-nourishment time periods along a 15 km expanse of the New Jersey shoreline. During the baseline years of sampling, silversides (primarily Menidia menidia) numerically dominated the surf-zone fish community. In 1997, coincident with beach nourishment operations, bluefish Pomatomus saltatrix became numerically dominant, increasing in abundance 10-fold. Bluefish were not captured near active beach nourishment sites and were significantly more abundant at reference stations than in the beach nourishment (treatment) area for 2 of 6 sampling dates in 1997. In contrast, northern kingfish Menticirrhus saxatilis were more abundant at treatment stations in 1997, and on one occasion congregated at the stations undergoing active sand replenishment. The feeding habits of Atlantic silversides and northern kingfish were consistent throughout the study period. In 1997, prey biomass was greater in fish caught at treatment stations when significant differences occurred. Prey consisted primarily of benthic invertebrates such as polychaetes and mole crabs. Amphipods and insects, which probably originated from groins and terrestrial sources respectively, were also common prey items and were present in plankton samples. Retrospective power analysis indicates that an approximate 3-fold difference in mean fish abundance was the minimum detectable effect size between reference and treatment areas. Beach nourishment impacts on the surf zone fish monitored in this study were restricted to localized attraction (northern kingfish) and avoidance (bluefish) responses to the beach nourishment operation.
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Within the next few decades, large underwater structures of thousands of wind turbines in the northern European shelf seas will substantially increase the amount of habitat available for mobile demersal megafauna. As a first indication of the possible effects of this large scale habitat creation on faunal stocks settling on hard substrata, we compared selected taxa of the mobile demersal megafauna (decapods and fish) associated with the foundation of an offshore research platform (a wind-power foundation equiva-lent) with those of five shipwrecks and different areas of soft bottoms in the southern German Bight, North Sea. When comparing the amount of approximately 5000 planned wind-power foundations (covering 5.1 Â 10 6 m 2 of bottom area) with the existing number of at least 1000 shipwrecks (covering 1.2 Â 10 6 m 2 of bottom area), it becomes clear that the southern North Sea will provide about 4.3 times more available artificial hard substratum habitats than currently available. With regard to the fauna found on shipwrecks, on soft substrata and on the investigated wind-power foundation, we predict that the amount of added hard substrata will allow the stocks of substrata-limited mobile demersal hard bottom species to increase by 25e165% in that area. The fauna found at the offshore platform foundations is very similar to that at shipwrecks. Megafauna abundances at the foundations, however, are lower compared to those at the highly fractured wrecks and are irregularly scattered over the foundations. The upper regions of the platform construction (5 and 15 m depth) were only sparsely colonized by mobile fauna, the anchorages, however, more densely. The faunal assemblages from the shipwrecks and the foundations, respectively, as well as from the soft bottoms clearly differed from each other. We predict that new wind-power foun-dations will support the spread of hard bottom fauna into soft bottom areas with low wreck densities.
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‘Noordzeewind’ (a Nuon and Shell Wind Energy consortium) exploits a wind farm with 36 wind turbines off the coast of Egmond aan Zee: the Offshore Wind farm Egmond aan Zee (OWEZ). This project serves to evaluate the economical, technical, ecological and social effects of offshore wind farms in general. To gather knowledge which will result from this project, a Monitoring and Evaluation Program (NSW6MEP) has been developed. Knowledge on environmental impact gained by this project will be made available to all parties involved in the realization of large6scale offshore wind farms. The construction and operation of offshore wind farms may result in possible negative impacts on fish populations, e.g. disturbance by noise or electromagnetic fields around cables, and consequent loss and degradation of habitats. On the other hand, due to the creation of new structures, i.e. additional habitats, that might act as artificial reefs or fish aggregation devices in combination with banning fisheries and shipping within wind farms, also positive impacts on fish populations are possible (Inger et al. 2009). In the latter case, wind farms might act as marine6protected areas or refuges for some fish species. The overall effect of the potential negative and positive impacts of the construction and operation of wind farms for fish is highly dependent on individual behavioural responses of fish to wind farms. This study focuses on exploring the potential benefits of the wind farm OWEZ, i.e. whether the wind farm can act as a refuge against fisheries for some fish species, by studying individual behaviour of fish during the operation phase of the wind farm. A key factor in this is individual residence time of fish within the wind farm. The longer individual fish spend in the wind farm, the stronger potential benefit of wind farms can be expected.
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A significant expansion of offshore windpower is expected ill northwestern Europe in the near future. Little is known about the impacts it may have on the marine environment. Here, we investigate the potential for wind turbines to function as artificial reefs and fish aggregation devices (FADs), i.e., whether they would locally increase fish densities or alter fish assemblages. Fish communities and habitat composition were investigated using visual transects at two windpower farms off the southeastern coast of Sweden. central Baltic Sea. Fish abundance was greater in the vicinity of the turbines than in surrounding areas, while species richness and Shannon-Wiener diversity (H') were similar. On the monopiles of the turbines, fish community structure was different, and total fish abundance was greater. while species richness and diversity (H') were lower than oil the surrounding seabed. Blue mussels and barnacles covered most of the submerged parts of the turbines. Oil the seabed. more blue mussels and a lesser cover of red algae were recorded around the power plants than elsewhere. Results from this study suggest that offshore windfarms may function as combined artificial reefs and fish aggregation devices for small demersal fish. (c) 2006 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
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Intensive exploitation of the marine environment by mankind can alter the natural habitat of marine organisms drastically. The addition of artificial hard substrates (e.g. shipwrecks and wind turbine foundations) to soft-sediment sandy bottoms is a pervasive example of an anthropogenic habitat change. To investigate the importance of hard substrate habitats for demersal fish species, we studied the spatio-temporal variability for two commercially important species, Atlantic cod (Gadus morhua) and pouting (Trisopterus luscus), from 2009 to 2011 at three different habitats in the Belgian part of the North Sea (BPNS), i.e. windmill artificial reefs (WARs), shipwrecks and sandy bottoms. Our results showed that population densities of both species were highly enhanced at the hard substrate habitats in comparison to the sandy sediments. The highest catch-per-unit effort values for both species were recorded around the WARs, which indicated distinct aggregation around the wind turbine foundations. In addition, the observed aggregation at the hard substrates differed between seasons. Highest population densities were observed in summer and autumn, i.e. the most intensive feeding period for both fishes.We conclude that the distribution and behaviour of Atlantic cod and pouting is affected by the presence and complexity of artificial hard substrates on the seabed.
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The spatial scales at which the dynamics of subpopulations are synchronized affect regional population persistence and reflect the operational spatial scales of factors regulating populations. I examined phase synchrony in the fluctuations of age-0 winter flounder (Pseudopleuronectes americanus) production among 19 southern New England (SNE), USA, coastal nurseries. From 1990 to 2004, nursery production was synchronized at scales up to similar to 200 km based on spatial trends in cross-correlations of first-differenced age-0 abundance time series. However, sliding window analysis of 1975-2005 time series collected in six nurseries <= 55 km apart in northern SNE indicated that synchrony increased from low to high values in the early 1990s. Synchrony in production also increased among three nurseries <= 65 km apart in southern SNE from 1984 to 2004. Thus, interannual fluctuations in nursery production appeared to become synchronized at coarser spatial scales throughout SNE during the 1990s. This coarsening of the spatial scale of control of winter flounder nursery production was coincident with an increase in the frequency of springs with warm temperatures believed to negatively affect early life history processes. Spatial synchronization of winter flounder nursery ground production could destabilize the age-class structure and population dynamics in the region.
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Two widely-recognized hypotheses propose that increases in fish abundance at artificial reefs are caused by (a) the attraction and redistribution of existing individuals, with no net increase in overall abundance and (b) the addition of new individuals by production, leading to a net increase in overall abundance. Inappropriate experimental designs have prevented many studies from discriminating between the two processes. Eight of 11 experiments comparing fish abundances on artificial reefs with those on adjacent soft bottom habitats were compromised by a lack of replication or spatial interspersion in the design itself. Only three studies featured proper controls and replicated designs with the interspersion of reef and control sites. Goodness of fit tests of abundance data for 67 species from these studies indicated that more fishes occur on reefs than on controls, particularly for species that typically occur over hard substrata. Conversely, seagrass specialists favour controls over reefs. Changes in the appearance of fish abundance trajectories driven by manipulation of sampling intervals highlight the need for adequate temporal sampling to encompass key life history events, particularly juvenile settlement. To ultimately determine whether attraction and production is responsible for increased abundances on reefs, requires two experimental features: 1) control sites, both interspersed among artificial reefs and at reef and non-reef locations outside the test area and 2) incorporation of fish age and length data over time. Techniques such as otolith microchemistry, telemetry and stable isotope analysis can be used to help resolve feeding and movement mechanisms driving attraction and production.
Article
1Global-scale environmental degradation and its links with non-renewable fossil fuels have led to an increasing interest in generating electricity from renewable energy resources. Much of this interest centres on offshore renewable energy developments (ORED). The large scale of proposed ORED will add to the existing human pressures on coastal ecosystems, therefore any ecological costs and benefits must be determined.2The current pressures on coastal ecology set the context within which the potential impacts (both positive and negative) of offshore renewable energy generation are discussed.3The number of published peer-review articles relating to renewable energy has increased dramatically since 1991. Significantly, only a small proportion of these articles relate to environmental impacts and none considers coastal ecology.4Actual or potential environmental impact can occur during construction, operation and/or decommissioning of ORED.5Construction and decommissioning are likely to cause significant physical disturbance to the local environment. There are both short- and long-term implications for the local biological communities. The significance of any effects is likely to depend on the natural disturbance regime and the stability and resilience of the communities.6During day-to-day operation, underwater noise, emission of electromagnetic fields and collision or avoidance with the energy structures represent further potential impacts on coastal species, particularly large predators. The wider ecological implications of any direct and indirect effects are discussed.7Synthesis and applications. This review demonstrates that offshore renewable energy developments will have direct and, potentially, indirect consequences for coastal ecology, with these effects occurring at different scales. Ecologists should be involved throughout all the phases of an ORED to ensure that appropriate assessments of the interaction of single and multiple developments with the coastal environment are undertaken.
Article
The genetic population structure of winter flounder larvae was examined in Narragansett Bay, RI. Winter flounder larvae collected from 20 stations within Narragansett Bay and one station outside of the Bay were analyzed for six microsatellite loci. When analyzed by geographic collection sites, there were 16 distinct genetic populations of winter flounder larvae (R ST values from 0.1 to 0.6). The presence of distinct genetic populations was supported by assignment of individual larvae to populations by Bayesian analysis. Bayesian analysis resulted in 14 distinct genetic populations that overlapped with the geographically distributed populations (R ST values from 0.1 to 0.6). Young-of-the-year juveniles collected in the same year as the larvae were also analyzed at the same six microsatellite loci. Juveniles were assigned to larvae populations by both a Bayesian approach and a neural network approach. Juveniles collected from within Narragansett Bay were found to arise from geographically adjacent Narragansett Bay winter flounder larval populations (>99%), suggesting no widespread movement of juveniles away from spawning grounds. These results are discussed in the context of winter flounder population biology in Narragansett Bay, RI.
Article
A significant expansion of offshore wind power is expected in the near future, with thousands of turbines in coastal waters, and various aspects of how this may influence the coastal ecology including disturbance effects from noise, shadows, electromagnetic fields, and changed hydrological conditions are accordingly of concern. Further, wind power plants constitute habitats for a number of organisms, and may locally alter assemblage composition and biomass of invertebrates, algae and fish. In this study, fouling assemblages on offshore wind turbines were compared to adjacent hard substrate. Influences of the structures on the seabed were also investigated. The turbines differed significantly from adjacent boulders in terms of assemblage composition of epibiota and motile invertebrates. Species number and Shannon–Wiener diversity were, also, significantly lower on the wind power plants. It was also indicated that the turbines might have affected assemblages of invertebrates and algae on adjacent boulders. Off shore wind power plant offer atypical substrates for fouling assemblages in terms of orientation, depth range, structure, and surface texture. Some potential ecological implications of the addition of these non-natural habitats for coastal ecology are discussed.
Article
A substantial expansion of offshore wind farms in the North Sea has been planned, inducing a growing interest in the effects of these artificial habitats on the marine environment. Numerous researches have been done to consider the possible effects of wind farms. However, to date little research investigated actual effects on the ichthyofauna.This study provides the first insights into the use of the artificial hard substrates by Trisopterus luscus (pouting) at the Thorntonbank wind farm in the Belgian part of the North Sea.Scuba diving operated visual surveys around one wind turbine revealed a distinctly higher pouting population size and biomass (i.e. 22 000 individuals yielding a total biomass of 2700 kg) as compared to the population size present at the soft sediments surrounding the wind turbines. Stomach content analyses further demonstrated the dietary preference for prey species that lived on the turbines (i.e. Jassa herdmani and Pisidia longicornis). Yet, the present study clearly demonstrates that wind turbines built at sea may attract fish populations considerably, possibly related to the enhanced provision of resident food items on the turbines.
Article
BACI (Before/After and Control/Impact) sampling is widely used in investigations of environmental impacts on mean abundance of a population. The principle is that an anthroppogenic disturbance in the “impact” location will cause a different pattern of change from before to after it starts compared with natural change in the control location. This can be detectable efficiently as a statistical interaction in an analysis of variance of the data. Usually, samples are taken at replicated, random intervals of time before and after the putative impact starts; this ensures that chance temporal fluctuations in either location do not confound the detection of an impact. These designs are, however, insufficient because any location-specific temporal difference that occurs between the two locations will be interpreted as an impact even if it has nothing to do with the human disturbance. Alternatively, abundance in the single control location may change in the same direction, cancelling the effects of an impact. Here, asymmetrical designs are developed that compare the temporal change in a potentially impacted location with those in a randomly-selected set of control locations. An impact must cause a different temporal change in the disturbed location from what would be expected in similar locations. This can be detected for short-term (pulse) or long-term (press) impacts by different patterns of sigficance in the temporal interactions between of sampling and locations. Frolm these novel designs, tests are that demonstrate whether an usual pattern of temporal change in abundance of organisms is specific to the supposedly impacted location and correlated with the onset of the disturbance. Examples are presented of how to use these designs to detect impacts at different spatial scales. Other aspects of their use are discussed.
Article
The development of off-shore wind farms along the coastline of north-west Europe is rapidly increasing; it is therefore important to study how this will affect the marine environment. The present study modelled the growth and feed-backs of blue mussels in natural beds and on turbine foundations in an off-shore wind farm (OWF) located in a shallow coastal ecosystem by coupling a dynamic energy budget (DEB) model to a small-scale 3D hydrodynamic–biogeochemical model. The model results showed that blue mussels located higher up in the water column on turbine pillars achieved a 7–18 times higher biomass than those located on the scour protection because the former experience an enhanced advective food supply. Secondly, the high biomasses of blue mussels on foundations created local ‘hot spots’ of biological activity and changed ecosystem dynamics due to their feed-backs e.g. ingestion of microplankton and copepods, excretion of ammonium and egestion of faecal pellets. The model results were supported by field measurements around foundations of Chl a concentrations and biomasses of the fauna community. Our study emphasised that OWFs seem to be particularly favourable for blue mussels in the western Baltic Sea and that the functioning of the OWFs as artificial reef ecosystems depends upon how the blue mussels interact with their local pelagic and benthic environment.
Article
In this study we investigate small scale distribution of pelagic fish within a windfarm by means of a high resolution sonar (DIDSON, Dual frequency IDentification SONar; Soundmetrics). In addition we assess the bias of small scale variations induced by the effects of wind turbines (monopiles) on distribution of the pelagic fish community in the hydro acoustic surveys carried out on the OWEZ Near Shore Wind farm (NSW).
Article
To resolve varied and sometimes conflicting accounts of spawning and habitat characteristics for winter flounder Pseudopleuronectes americanus, seasonal patterns in abundance and reproductive condition were investigated in the New York Bight, near the southern edge of their current reproductive range. Fish were collected from trawl surveys on the inner continental shelf from October 2006 to October 2007. Pseudopleuronectes americanus were most abundant during January and April surveys, were rarely collected in August, with intermediate abundances in June and October. Measurements of fish condition [hepato-somatic index (I(H)), condition factor (K) and the per cent dry mass of muscle tissue (%M(D))] and reproductive condition [gonado-somatic index (I(G))] were determined to evaluate seasonal changes in energy accumulation and depletion and reproduction. Males and females had similar patterns in body and reproductive condition, although the magnitude of change was greater for females. I(H) values were highest during spring and early summer, suggesting increased feeding following spawning. K and %M(D) increased through spring and summer then declined in the autumn and winter concurrent with gonadal development. Gonads began developing in the autumn, and in January, I(G) values approached spawning levels, with many spent individuals collected in spring. Within these general patterns, however, there was a large degree of variability among individuals, and a few mature non-reproductive ('skipped spawning') females were observed. In the period after spawning, increased energy intake, indicated by increased I(H), may influence reproductive output since this energy is gradually transferred to the muscle and used for gonadal development in the forthcoming year. The occurrence of ripening individuals on the inner continental shelf in January suggests that these fish either rapidly move into estuaries to spawn by February-March or they remain on the inner shelf to spawn, or some combination of these. Future studies should evaluate these possibilities, as both estuarine and inner shelf habitats are potentially affected by activities such as dredging, sand dredging and wind energy development.
Article
Marine renewable developments have raised concerns over impacts of underwater noise on marine species, particularly from pile-driving for wind turbines. Environmental assessments typically use generic sound propagation models, but empirical tests of these models are lacking. In 2006, two 5MW wind turbines were installed off NE Scotland. The turbines were in deep (>40m) water, 25km from the Moray Firth Special Area of Conservation (SAC), potentially affecting a protected population of bottlenose dolphins. We measured pile-driving noise at distances of 0.1 (maximum broadband peak to peak sound level 205dB re 1microPa) to 80km (no longer distinguishable above background noise). These sound levels were related to noise exposure criteria for marine mammals to assess possible effects. For bottlenose dolphins, auditory injury would only have occurred within 100m of the pile-driving and behavioural disturbance, defined as modifications in behaviour, could have occurred up to 50km away.
A framework for regulating underwater noise during pile driving
  • M H Andersson
  • S Andersson
  • J Ahlsén
  • B L Andersson
  • J Hammar
  • L K G Persson
  • J Pihl
  • P Sigray
  • A Wikström
Andersson, M.H., Andersson, S., Ahlsén, J., Andersson, B.L., Hammar, J., Persson, L.K.G., Pihl, J., Sigray, P., Wikström, A., 2017. A framework for regulating underwater noise during pile driving. In: A Technical Vindval Report. Stockholm, Sweden, Swedish Environmental Protection Agency (ISBN 978-91-620-6775-5).
Offshore Wind Farms in the Belgian Part of the North Sea: Heading for an Understanding of Environmental Impacts
  • F Kerckhof
  • B Rumes
  • A Norro
  • J S Houziaux
  • S Degraer
Kerckhof, F., Rumes, B., Norro, A., Houziaux, J.S., Degraer, S., 2012. A comparison of the first stages of biofouling in two offshore wind farms in the Belgian part of the North Sea. In: Degraer, S., Brabant, R., Rumes, B. (Eds.), Offshore Wind Farms in the Belgian Part of the North Sea: Heading for an Understanding of Environmental Impacts. Royal Belgian Institute of Natural Sciences, Management Unit of the North Sea Mathematical Models, Marine Ecosystem Management Unit (155 pp. + annexes).