William Sanderson

The Substantial First Impact of Bottom Fishing on Rare Biodiversity Hotspots: A Dilemma for Evidence-Based Conservation

This study describes the impact of the first passage of two types of bottom-towed fishing gear on rare protected shellfish-reefs formed by the horse mussel Modiolus modiolus (L.). One of the study sites was trawled and the other was scallop-dredged. Divers collected HD video imagery of epifauna from quadrats at the two study sites and directed infaunal samples from one site. The total number of epifaunal organisms was significantly reduced following a single pass of a trawl (90%) or scallop dredge (59%), as was the diversity of the associated community and the total number of M. modiolus at the trawled site. At both sites declines in anthozoans, hydrozoans, bivalves, echinoderms and ascidians accounted for most of the change. A year later, no recovery was evident at the trawled site and significantly fewer infaunal taxa (polychaetes, malacostracans, bivalves and ophuroids) were recorded in the trawl track. The severity of the two types of impact reflected the undisturbed status of the habitats compared to previous studies. As a ‘priority habitat’ the nature of the impacts described on M. modiolus communities are important to the development of conservation management policy and indicators of condition in Marine Protected Areas (EU Habitats Directive) as well as indicators of ‘Good Environmental Status’ under the European Union Marine Strategy Framework Directive. Conservation managers are under pressure to support decisions with good quality evidence. Elsewhere, indirect studies have shown declines of M. modiolus biogenic communities in fishing grounds. However, given the protected status of the rare habitat, premeditated demonstration of direct impact is unethical or illegal in Marine Protected Areas. This study therefore provides a unique opportunity to investigate the impact from fishing gear whilst at the same time reflecting on the dilemma of evidence-based conservation management.

Small-scale variation within a Modiolus modiolus (Mollusca: Bivalvia) reef in the Irish Sea. II. Epifauna recorded by divers and cameras

The spatial heterogeneity of epifauna on a Modiolus modiolus reef off north-west Wales was investigated using divers. The community associated with these horse mussels was similar to that described previously from Loch Creran and the north basin of Strangford Lough. Some differences in epifauna may be attributable to the less sheltered nature of the site. Modiolus modiolus numbers and the associated epifaunal community were significantly different between ridge and trough sub-habitats. Troughs can be considered ‘reduced’ ridge communities whereas ridges have high densities of horse mussels and certain sessile taxa were correlated with their abundance. Modiolus modiolus aggregation as a competitive response to the feeding environment, enhanced food availability on ridges and sediment deposition amongst mussel clumps may start to explain the undulating bed-form. Patchiness in community composition and periodic cover by ophuroids has implications when considering the monitoring of the horse mussel community. Stratified, in situ recording of the highly populated ridges could improve the statistical sensitivity of monitoring horse mussel reefs whilst simultaneously focusing on the more sensitive indicators of fishing threats.

Predictive Habitat Modelling as a Tool to Assess the Change in Distribution and Extent of an OSPAR Priority Habitat under an Increased Ocean Temperature Scenario: Consequences for Marine Protected Area Networks and Management

The aims of this study were to determine the extent and distribution of an OSPAR priority habitat under current baseline ocean temperatures; to illustrate the prospect for habitat loss under a changing ocean temperature scenario; and to demonstrate the potential application of predictive habitat mapping in “future-proofing” conservation and biodiversity management. Maxent modelling and GIS environmental envelope analysis of the biogenic bed forming species, Modiolus modiolus was carried out. The Maxent model was tested and validated using 75%/25% training/test occurrence records and validated against two sampling biases (the whole study area and a 20km buffer). The model was compared to the envelope analysis and the area under the receiver operating characteristic curve (Area Under the curve; AUC) was evaluated. The performance of the Maxent model was rated as ‘good’ to ‘excellent’ on all replicated runs and low variation in the runs was recorded from the AUC values. The extent of “most suitable”, “less suitable” and “unsuitable” habitat was calculated for the baseline year (2009) and the projected increased ocean temperature scenarios (2030, 2050, 2080 and 2100). A loss of 100% of “most suitable” habitat was reported by 2080. Maintaining a suitable level of protection of marine habitats/species of conservation importance may require management of the decline and migration rather than maintenance of present extent. Methods applied in this study provide the initial application of a plausible “conservation management tool”.

Development and optimization of a standard method for extraction of microplastics in mussels by enzyme digestion of soft tissues

The authors compared procedures for digestion of mussel soft tissues and extraction of microplastics. Complete tissue digestion was achieved with 1M NaOH, 35% HNO3 , and protease at 9.6 UHb/mL (unit hemoglobin per mL); but use of HNO3 caused unacceptable destruction of some microplastics. Recovery of microplastics spiked into mussels was similar (93 ± 10%) for NaOH and enzyme digestions. The authors recommend use of industrial enzymes based on digestion efficiency, microplastic recovery, and avoidance of caustic chemicals. Environ Toxicol Chem 2017;36:947-951.

The Sea Empress oil spill (Wales, UK): Effects on Common Scoter Melanitta nigra in Carmarthen Bay and status ten years later

Carmarthen Bay, UK, regularly supports internationally important numbers (>16,000) of non-breeding Common Scoters Melanitta nigra. The spill of 72,000 tonnes of crude oil from the Sea Empress in 1996 affected birds both through direct mortality and likely pollution of key food resources. Numbers were greatly reduced following the spill, whilst changes in the distribution of birds within Carmarthen Bay suggested that potentially sub-optimal foraging zones were used. However, ten years after the incident, numbers of Common Scoter were no different to those recorded immediately before the spill. Compared to some other spills, rapid revival is evident. Numbers increased to pre-spill levels within three winters and distributional changes suggested a concurrent return to previously contaminated feeding areas, implying that the ecosystem had regenerated sufficiently to support its top predator. The importance of prolonged, standardised monitoring of bird numbers and distribution as indicators of ecological recovery from environmental damage is emphasised.

Re‐evaluation of marine benthic species of nature conservation importance: a new perspective on certain ‘lagoonal specialists’ with particular emphasis on Alkmaria romijni Horst (Polychaeta: Ampharetidae)

1. The ampharetid polychaete Alkmaria romijni (protected under the Wildlife and Countryside Act 1981) is recorded from a survey of intertidal mudflats on the south bank of the Humber Estuary (UK) in an apparently unusual habitat for the species. 2. The records from the Humber are considered together with other records which have been collated recently as part of a review of rare and scarce marine benthic species in the UK. Some of these records are ‘new’. 3. An assessment of records from the Humber and elsewhere suggests that this tidal estuarine habitat is not atypical for A. romijni. Furthermore, it is not clear why the species shows such a restricted distribution within the Humber. 4. A. romijni can now be shown to not be confined to brackish lagoons in the UK, but rather is found in muddy sediments in sheltered to very sheltered conditions in both lagoons and certain estuaries. The majority of current records are now estuarine in the UK, suggesting that A. romijni can no longer be classed as a ‘lagoonal specialist’ species as previously considered. 5. Based on all UK records, the species should be considered ‘scarce’ rather than ‘rare’ using current assessment criteria. On balance, however, it is concluded that it is probably still appropriate to maintain the protected status of A. romijni. 6. Two other ‘lagoonal specialist’ species—the starlet sea anemone Nematostella vectensis and the lagoon sand shrimp Gammarus insensibilis—indicate, in the light of new records, that the reappraisal of lagoonal specialist status is restricted, for the present, to A. romijni rather than being common to other species. 7. The work highlights that there is a need for a re-evaluation mechanism in the assessment of marine species considered to be of conservation importance. Copyright

Horse mussel reef ecosystem services: evidence for a whelk nursery habitat supporting a shellfishery

ABSTRACT Demonstrating the benefits that marine ecosystems provide to society can support marine spatial planning and enhance the protection of fragile, biodiverse habitats. However, the importance of ecosystem services provided by such habitats is rarely accounted for in spatial management due to a lack of detailed information. The present study investigated the ‘habitat provision’ ecosystem service delivered by horse mussel (Modiolus modiolus (L.)) reefs, a ‘Priority Marine Habitat’ in the NE Atlantic. By working with local fishers, the abundance and demographics of commercially important whelks (Buccinum undatum) were examined. B. undatum catches were three times higher on reef sites and a greater number of smaller individuals were caught on the reefs compared to off-reef habitats. We therefore show that these productive and physically complex mussel reefs are important feeding and nursery areas for whelks, demonstrating the ‘essential fish habitat’ value of the now rare M. modiolus reefs. The results are discussed in the context of marine spatial planning and the potential for historically more widespread shellfish habitats to have been capable of providing substantial ecosystem services.

Seabed Habitats of the Southern Irish Sea

Publisher Summary The Irish Sea is one of the busiest maritime regions of the United Kingdom and Ireland, and has great economic value to both countries in terms of its fisheries, aggregate resources, oil and gas reserves, and offshore power generation The sea contains a channel running along its center roughly oriented north–south and gradually shelves on both sides. Three primary sources of water movement exist through the southern Irish Sea—tidal flows, weather-related and density-driven movements. Of these, tidal flows are the most significant, with residual currents flowing in a northward direction through the area. A gradient of increasing salinity exists from north to south, and seasonal fronts are known to form to the north and south of the study area. However, tidal mixing is sufficient across much of the region to ensure that the water column remains well mixed throughout the year. The morphology and sediments of the southern Irish Sea are products of historic glacigenic processes and subsequent exposure to waves, storms, and tidal flows. The Irish Sea Ice Stream poured into the Irish Sea several times during the Quaternary period, and multiple generations of glacial incisions have been documented. Main pressures from anthropogenic activities come from fishing, dredging, shipping, and power generation, and the sea has been classified as a high impact area. Climate change impacts are also becoming evident from rising sea levels and temperature, the latter bringing about a gradual change in the biology of seabed communities in the eastern Irish Sea, and contributing to the spread of non-native species.

Commercially important species associated with horse mussel ( Modiolus modiolus ) biogenic reefs: A priority habitat for nature conservation and fisheries benefits

Horse mussel reefs (Modiolus modiolus) are biodiversity hotspots afforded protection by Marine Protected Areas (MPAs) in the NE Atlantic. In this study, horse mussel reefs, cobble habitats and sandy habitats were assessed using underwater visual census and drop-down video techniques in three UK regions. Megafauna were enumerated, differences in community composition and individual species abundances were analysed. Samples of conspicuous megafauna were also collected from horse mussel reefs in Orkney for stable isotope analysis. Communities of conspicuous megafauna were different between horse mussel habitats and other habitats throughout their range. Three commercially important species: whelks (Buccinum undatum), queen scallops (Aequipecten opercularis) and spider crabs (Maja brachydactyla) were significantly more abundant (by as much as 20 times) on horse mussel reefs than elsewhere. Isotopic analysis provided insights into their trophic relationship with the horse mussel reef. Protection of M. modiolus habitat can achieve biodiversity conservation objectives whilst benefiting fisheries also.

A tool for protected area management: multivariate control charts 'cope' with rare variable communities.

Performance assessment, impact detection, and the assessment of regulatory compliance are common scientific problems for the management of protected areas. Some habitats in protected areas, however, are rare and/or variable and are not often selected for study by ecologists because they preclude comparison with controls and high community variability makes meaningful change detection difficult. Shallow coastal saline lagoons are habitats that experience comparatively high levels of stress due to high physical variability. Lagoons are rare, declining habitats found in coastal regions throughout Europe (and elsewhere) where they are identified as one of the habitats most in need of protected area management. The infauna in the sediments of 25 lagoons were sampled. Temporal and spatial variation in three of these [protected] lagoons was investigated further over 5 years. In a multivariate analysis of community structure similarities were found between some lagoons, but in other cases communities were unique or specific to only two sites. The protected lagoons with these unique/specific communities showed significant temporal and spatial variation, yet none of the changes observed were attributed to human impacts and were interpreted as inherent variability. Multivariate control charts can operate without experimental controls and were used to assess community changes within the context of ‘normal’ lagoon variability. The aim of control chart analysis is to characterize background variability in a parameter and identify when a new observation deviates more than expected. In only 1 year was variability more than expected and corresponded with the coldest December in over 100 years. Multivariate control charts are likely to have wide application in the management of protected areas and other natural systems where variability and/or rarity preclude conventional analytical and experimental approaches but where assessments of condition, impact or regulatory compliance are nonetheless required.