Testing the resilience of dead maerl infaunal assemblages to the experimental removal and re-lay of habitat

An experimental trial to mitigate dredging impact was undertaken within Falmouth Harbour, UK, removing a surface layer of dead maerl for storage on a barge and allowing the channel to be deepened before re-laying the maerl. The resilience (resistance and recovery) of the habitat and faunal assemblage to this disturbance was assessed. Six sites each had 2 conditions - a manipulated treatment area where maerl (25 m2 plots, top 0.3 m) was removed, stored on a barge and re-laid by backhoe dredger and a control area - which were cored at 0 (before), 5 and 4 wk after re-lay. PERMANOVA was used to test for differences between condition and time using a 2-factor design. Results should not be extrapolated to live maerl habitats or to large, longlived fauna that may live within them. Following the mechanical disturbance, the maerl matrix structure was altered through loss of fine sediment from the lower half of cores (>10 cm). There was also a significant reduction in the number of taxa and abundance of infauna and a change in the assemblage composition. By Week 44, however, no such significant differences were evident, indicating that the infauna was in a state of recovery. The only response variable showing recovery was annelid biomass. The trial demonstrated that removing and re-laying the top 0.3 m of maerl habitat is technically feasible, and whilst some differences in the habitat structure following re-laying were evident, this did not affect the habitat quality enough to prevent recolonisation of infauna

Epibenthic assessment of a renewable tidal energy site.

Concern over global climate change as a result of fossil fuel use has resulted in energy production from renewable sources. Marine renewable energy devices provide clean electricity but can also cause physical disturbance to the local environment. There is a considerable paucity of ecological data at potential marine renewable energy sites that is needed to assess potential future impacts and allow optimal siting of devices. Here, we provide a baseline benthic survey for the Big Russel in Guernsey, UK, a potential site for tidal energy development. To assess the suitability of proposed sites for marine renewable energy in the Big Russel and to identify potential control sites, we compared species assemblages and habitat types. This baseline survey can be used to select control habitats to compare and monitor the benthic communities after installation of the device and contribute towards the optimal siting of any future installation

Optimal fishing effort benefits fisheries and conservation

AbstractThe ecosystem effects of all commercial fishing methods need to be fully understood in order to manage our marine environments more effectively. The impacts associated with the most damaging mobile fishing methods are well documented leading to such methods being removed from some partially protected areas. In contrast, the impacts on the ecosystem from static fishing methods, such as pot fishing, are less well understood. Despite commercial pot fishing increasing within the UK, there are very few long term studies (&gt; 1 year) that consider the effects of commercial pot fishing on temperate marine ecosystems. Here we present the results from a controlled field experiment where areas of temperate reef were exposed to a pot fishing density gradient over 4 years within a Marine Protected Area (MPA), simulating scenarios both above and below current levels of pot fishing effort. After 4 years we demonstrate for the first time negative effects associated with high levels of pot fishing effort both on reef building epibiota and commercially targeted species, contrary to existing evidence. Based on this new evidence we quantify a threshold for sustainable pot fishing demonstrating a significant step towards developing well-managed pot fisheries within partially protected temperate MPAs.</jats:p

Ecosystem benefits of adopting a whole-site approach to MPA management

Globally, nations are designating marine protected areas to recover and protect habitats and species. With targets to protect 30% of marine areas by 2030, the effectiveness of MPAs to protect designated space is important. In Lyme Bay (south-west UK), two co-located MPAs have each adopted different management styles to exclude mobile demersal fishing: a Special Area of Conservation (SAC) protecting the known extent of sensitive reef habitat and an area including a mosaic of reef and sedimentary habitats where the whole site is protected from mobile demersal fishing under a statutory instrument (SI). Underwater videography, both towed (individuals m−2) and baited (MaxN), was used to enumerate change over time of reef species (number of taxa, total abundance, functional richness and functional redundancy) in the MPAs and nearby control areas (2008–2019). Total abundance and functional redundancy of sessile taxa and functional richness of mobile taxa increased, while the number of sessile or mobile taxa, functional richness of sessile taxa, total abundance of mobile taxa or functional redundancy of mobile taxa did not differ from nearby control sites. Over time, both management styles did result in increases in sessile and sedentary taxa diversity relative to open controls, with increases in total abundance of 15% and 95% in the “feature-based” and whole-site MPAs, respectively, alongside increases in the number of sessile taxa of 44% over time in the “feature-based” MPA. However, the mobile taxa in the whole-site MPA showed levels of functional redundancy 7% higher than the “feature-based” MPA, indicative of a higher community resilience inside the whole-site MPA to perturbations, such as storms or biological invasions. Increases seen in the diversity of sessile taxa were expected only in areas where mobile demersal fishing was excluded (~46.8% of its areas). Therefore, if the whole “feature-based” MPA was consistently protected, we expected to see similar levels of increase in the functional extent of reef. While the “feature-based” MPA showed similar results over time to that of the “whole site,” the “whole site” showed higher levels of diversity, both taxonomical and functional

A simple mooring modification reduces impacts on seagrass meadows

AbstractMoorings can have a detrimental impact on seagrass, fragmenting the meadows, resulting in the habitat degradation. To reduce contact of the moorings with the seabed we attached small floats along the chain of a traditional swing mooring and monitored the ecological impacts of this modified mooring, with reference to a standard swing mooring, in a seagrass meadow under high tidal influence. After three years, seagrass density surrounding the modified mooring was over twice as high as that of the standard mooring, with blade length surrounding the modified mooring also found to exceed that of the standard mooring. Seagrass-associated epifaunal species richness was twice as high surrounding the modified mooring compared to the standard mooring. Sediment composition was considerably finer at the modified mooring, indicative of increased disturbance surrounding the standard mooring. A simple modification to existing swing moorings can mitigate some of the impacts of moorings on seagrass meadows, whilst accommodating for tidal fluctuations. The scale of the differences observed between the mooring types demonstrates the susceptibility of seagrass meadows to damage from swing moorings. Given the ecological importance of these habitats, it is crucial that action is taken to reduce further degradation, such as that demonstrated here.</jats:p

Shipwrecks act as de facto Marine Protected Areas in areas of heavy fishing pressure

Ubiquitous, industrial use of bottom‐towed fishing gear since the 1800s has altered marine communities and ecosystem services. Outside of legal protection, only areas inaccessible to trawlers are offered any protection. Shipwrecks present hazards to fishing gear and are rarely subject to trawling pressure. As many have been in situ for &gt;100 years, they offer a baseline of ecological potential when trawling pressure is reduced or removed. Five shipwrecks were surveyed off the Berwickshire coast, some within the Static Gear Reserve and others outside. Video transects were collected of shipwrecks, the surrounding 50 m radius and control locations &gt;150 m from the wreck site. Species identified were assigned a category based on their vulnerability to trawling. The effect of distance from a shipwreck on ecological communities within sites Open and Closed to trawling was investigated. The ecological importance of shipwrecks increased relative to trawling pressure. In Open sites, abundance was 340% greater on Wreck locations than Control. Conversely, within Closed sites, abundance was 149% greater in Control locations than Wreck. In Open sites, shipwreck communities are more similar to those in Closed sites, than to the habitat surrounding the shipwreck. Vulnerable species, mostly large, sessile filter feeders, are almost entirely absent from Open sites, but account for ~28% of the total abundance on shipwrecks in Closed sites. This study offers a quantifiable method to evaluate the ecological contribution of shipwrecks in disturbed areas and suggests their role may warrant further research, and consideration in conservation policy, such as inclusion in 30 × 30 objectives. Our findings also demonstrate the possible ecological gains of expanding or including static gear reserves across Marine Protected Areas

Assessing the impact of introduced infrastructure at sea with cameras: A case study for spatial scale, time and statistical power

This is the Final version. Available on open access from Elsevier via the DOI in this recordDetecting the effects of introduced artificial structures on the marine environment relies upon research and monitoring programs that can provide baseline data and the necessary statistical power to detect biological and/or ecological change over relevant spatial and temporal scales. Here we report on, and assess the use of, Baited Remote Underwater Video (BRUV) systems as a technique to monitor diversity, abundance and assemblage composition data to evaluate the effects of marine renewable energy infrastructure on mobile epi-benthic species. The results from our five-year study at a wave energy development facility demonstrate how annual natural variation (time) and survey design (spatial scale and power) are important factors in the ability to robustly detect change in common ecological metrics of benthic and bentho-pelagic ecosystems of the northeast Atlantic. BRUV systems demonstrate their capacity for use in temperate, high energy marine environments, but also how weather, logistical and technical issues require increased sampling effort to ensure statistical power to detect relevant change is achieved. These factors require consideration within environmental impact assessments if such survey methods are to identify and contribute towards the management of potential positive or negative effects on benthic systems.Natural Environment Research CouncilEngineering and Physical Sciences Research CouncilIntelligent Energy Europe (IEE)European Regional Development Fund (ERDF

The socio-economic impact of Marine Protected Areas in Jersey: A fishers’ perspective

Marine Protected Areas (MPAs) are advocated as tools to support sustainable fisheries and biodiversity by excluding the most destructive fishing practices. Some MPAs protect the whole-site of habitat mosaics from bottom-towed fishing but most only restrict damaging activities from specific evidenced conservation features. Social and economic factors influence the success of an MPA but the impact of spatial management changes to local fisheries is rarely captured in post MPA designation monitoring. In Jersey, Channel Islands, two offshore MPAs were designated in 2017 that are managed following the whole-site approach. This study provides an insight into the overall economic importance of key fishery species (whelk (Buccinum undatum), brown crab (Cancer pagurus), scallop (Pecten maximus), lobster (Homarus gammarus), and spider crab (Maja brachydactyla) to local fishing fleets and the impact of the MPAs on local, small-scale fishers in Jersey. Total landings (kg and £) in Jersey pre and post MPA designation were calculated from logbook and primary sales data and a structured interview was developed and tested as a research tool to document the impact (positive and negative) of the MPA designation on local fishers. Specific questions were designed to elicit both quantitative and qualitative data relating to the participants (n = 21) fishing activity; support for the MPAs; income and job satisfaction; subjective well-being and current sales strategies. The results demonstrate that one mobile gear vessel respondent was displaced from traditional fishing grounds as a result of the MPA designation. Fishers also reported an increase in static fishing inside the MPAs, post designation. Generally, there are high levels of support for the MPA from static fleet respondents. In the first year since designation there have been no reported changes to catch (kg, £). Mobile gear fishers reported a lower subjective wellbeing and satisfaction with their job and income than static gear fishers, despite greater profits. The major concern reported by the mobile fleet that contributed to their stress levels, was not attributed to the MPA designations but related to conflict with French static net fisheries operating outside of the MPAs. Ongoing support for Jersey's fishers and securing a sustainable and fulfilling livelihood will require further spatial management of fisheries outside of the MPAs with a possibility of setting gear or effort limits on static fishereis within the MPAs

Rewilding the Sea? A Rapid, Low Cost Model for Valuing the Ecosystem Service Benefits of Kelp Forest Recovery Based on Existing Valuations and Benefit Transfers

Kelp forests and seagrasses are important carbon sinks that are declining globally. Rewilding the sea, through restoring these crucial habitats, their related biodiversity and ecosystem contributions, is a movement and concept, gathering pace in the United Kingdom and globally. Yet understanding of the economic costs and benefits for setting areas of the sea aside—and removing some human impacts from them—is not well understood. The potential benefits and distributional impacts on marine users and wider society is critical to make evidence based decisions. Ensuring that areas of the sea recover, and that the impacts (both positive and negative) are understood, requires targeted research to help guide decisions to optimize the opportunity of recovery, while minimizing any negative impacts on sea users and coastal communities. We approach the problem from an ecosystem services perspective, looking at the opportunity of restoring a kelp bed in Sussex by removing fishing activity from areas historically covered in kelp. Development of an ecosystem services valuation model showed restoring kelp to its highest mapped past extent (96% greater, recorded in 1987) would deliver a range of benefits valued at over £ 3.5 million GBP. The application of an ecosystem services approach enabled the full range of benefits from habitat restoration to be assessed. The results and the gaps identified in site specific data and values for this area, have broader implications in fisheries management and natural resource management tools for restoring marine habitats and ecosystems in the United Kingdom.</jats:p