Revealing species assembly rules in nematode communities

Species assemblages are not randomly assembled from a local species pool; they often show segregated or aggregated distribution patterns. These patterns may be attributed to both biotic and abiotic factors. On a large scale abiotic factors may be important, while on a smaller scale other factors such as species interactions may become essential. Here we will focus on small-scale patterns in nematode communities. Species patterns are generally revealed by null models based on presence/absence data. Since there is an increasing chance of falsely rejecting the null hypothesis of a random assembled community with increasing matrix size, we used an algorithm generating independent null matrices and applied a large number of swap attempts to build a null matrix. Moreover, we applied an additional test to reveal the susceptibility of the analyses of checker and the C-, T- and Vscore to a Type I error for randomised data. To minimise the influence of the abiotic environment, we restricted the swapping algorithm of the null model to the replicate samples of one sampling event. Since stronger species interactions are expected for species of the same functional type, the nematode data was split according to the four feeding types defined by Wieser (1953). Our data indicate that species tend to aggregate and co-occur more often in some replicate samples than would be expected from a random species distribution of the local species pool. This is in accordance with the patchy distribution patterns known for nematode species. These aggregated patterns are also found for the different feeding types. The factors causing these aggregated patterns cannot be established since they are not included in the data, but the data do indicate that competitive exclusion is unlikely at the scale of a sample core

Impacts of trawling on diversity, biomass and structure of meiofaunal assemblages

Abstract Disturbance due to trawling reduces the biomass and production of macro-infaunal invertebrate communities, implying that their total food-consumption rate will fall, and that production (carbon) reaching the sea floor will be processed by other animals that can withstand the effects of trawling. Meiofauna may be resistant to disturbance by trawling because they are likely to be resuspended rather than killed by trawls and because their short generation times would allow them to withstand elevated mortality. We used a BACI experimental approach to investigate the short-term effects of beam trawling on the diversity, biomass and community structure of meiofauna on real fishing grounds in the southern North Sea. Experiments at two locations showed that there were no short-to medium-term (1-392 days after experimental trawling) trawling impacts on meiofaunal diversity or biomass, but that there were mild effects on community structure. Any impacts due to trawling were minor in relation to seasonal changes in the meiofaunal communities. We assessed the power of our experiments to detect the effects of trawling and recorded a 44-85% chance of detecting a 50% change in species richness and a 65% chance of detecting an order-of-magnitude change in biomass. The power to detect changes in total abundance, however, was low (between 11% and 12% power for detecting a change of 50%). We suggest that meiofauna are more resistant to disturbance by beam trawling than are macrofauna and that they have the potential to withstand the effects of chronic trawling on real fishing grounds and to retain a key role in energy cycling

What’s hot and what’s not: making sense of biodiversity ‘hotspots’

Conserving biogeographic regions with especially high biodiversity, known as biodiversity ‘hotspots’, is intuitive because finite resources can be focussed towards manageable units. Yet, biodiversity, environmental conditions and their relationship are more complex with multidimensional properties. Assessments which ignore this risk failing to detect change, identify its direction or gauge the scale of appropriate intervention. Conflicting concepts which assume assemblages as either sharply delineated communities or loosely collected species have also hampered progress in the way we assess and conserve biodiversity. We focus on the marine benthos where delineating manageable areas for conservation is an attractive prospect because it holds most marine species and constitutes the largest single ecosystem on earth by area. Using two large UK marine benthic faunal datasets, we present a spatially gridded data sampling design to account for survey effects which would otherwise be the principal drivers of diversity estimates. We then assess γ‐diversity (regional richness) with diversity partitioned between α (local richness) and β (dissimilarity), and their change in relation to covariates to test whether defining and conserving biodiversity hotspots is an effective conservation strategy in light of the prevailing forces structuring those assemblages. α‐, β‐ and γ‐diversity hotspots were largely inconsistent with each metric relating uniquely to the covariates, and loosely collected species generally prevailed with relatively few distinct assemblages. Hotspots could therefore be an unreliable means to direct conservation efforts if based on only a component part of diversity. When assessed alongside environmental gradients, α‐, β‐ and γ‐diversity provide a multidimensional but still intuitive perspective of biodiversity change that can direct conservation towards key drivers and the appropriate scale for intervention. Our study also highlights possible temporal declines in species richness over 30 years and thus the need for future integrated monitoring to reveal the causal drivers of biodiversity change

An approach for assessing and ranking fisheries management scenarios in spatially delimited marine areas

Spatial restrictions to human activities such as bottom trawling are increasingly used to improve the ecological condition of disturbed habitats. Such management interventions typically have socio-economic consequences, which creates a challenge for those making decisions about which activities should be restricted and where restrictions should apply. We present an approach for predicting the effects of fisheries management scenarios in spatially delimited marine areas and ranking them—using a loss function—according to how well they achieve desired outcomes across a set of ecological and socio-economic indicators. This approach is demonstrated by simulating alternative fishing gear restrictions and zoning options within a hypothetical marine protected area (MPA). Relative benthic status (RBS; an indicator of ecological condition) and relative catch value (RCV; an indicator of potential economic cost) were estimated for the baseline environment and 21 potential management scenarios. The rank order depended on which indicator was prioritized (i.e. whether RBS or RCV was given greater weighting in the loss function), with the top-ranked scenarios in each case involving considerably different management measures. The methods presented can be applied anywhere using locally or strategically relevant indicators to help identify spatial fisheries management measures that minimize ecological and socio-economic trade-offs

Evidence for the effects of decommissioning man-made structures on marine ecosystems globally: a systematic map protocol

Background: Numerous man-made structures (MMS) have been installed in various parts of the ocean (e.g. oil and gas structures, offshore wind installations). Many are now at, or nearing, the end of their intended life. Currently, we only have a limited understanding of decommissioning effects. In many locations, such as the North Sea, regulations restrict decommissioning options to complete removal, with little consideration of alternative management options might offer. To generate a reliable evidence-base to inform the decision-making processes pertaining to marine MMS management, we propose a wide-encompassing systematic map of published research on the ecosystem effects (including ecosystem services) of marine MMS while in place and following cessation of operations (i.e. including effects of alternative decommissioning options). This map is undertaken as part of the UKRI DREAMS project which aims to develop a system to show the relative effects of implementing different decommissioning strategies in the North Sea. Method: For the purpose of this map, we will keep our focus global, in order to subsequently draw comparisons between marine regions. The proposed map will aim to answer the following two primary questions: 1. What published evidence exists for the effects of marine man-made structures while in place on the marine ecosystem? 2. What published evidence exists for the effects of the decommissioning of marine man-made structures on the marine ecosystem? The map will follow the Collaboration for Environmental Evidence Guidelines and Standards for Evidence Synthesis in Environmental Management. Searches will be run primarily in English in at least 13 databases and 4 websites. Returns will be screened at title/abstract level and at full-text against pre-defined criteria. Relevant meta-data will be extracted for each study included. Results will be used to build a database of evidence, which will be made freely available. This map, expected to be large, will improve our knowledge of the available evidence for the ecosystem effects of MMS in the global marine environment. It will subsequently inform the production of multiple systematic-reviews and meta-analyses

Evidence for the effects of decommissioning man-made structures on marine ecosystems globally: a systematic map

Background: Many marine man-made structures (MMS), such as oil and gas platforms or offshore wind turbines, are nearing their ‘end-of-life’ and require decommissioning. Limited understanding of MMS decommissioning effects currently restricts the consideration of alternative management possibilities, often leaving complete removal as the only option in certain parts of the world. This evidence-base describes the ecosystem effects of marine MMS whilst in place and following cessation of operations, with a view to informing decision-making related to their potential decommissioning. Method: The protocol used to create this map was published a priori. Systematic searches of published, literature in English were conducted using three bibliographic databases, ten specialist organisational websites or repositories, and one search engine, up to early 2021. A total of 15,697 unique articles were identified as potentially relevant to our research questions, of which 2,230 were screened at the full-text level. Of that subset, 860 articles met all pre-defined eligibility criteria. A further 119 articles were identified through “snowballing” of references from literature reviews. The final database consists of 979 articles. For each article included, metadata were extracted for key variables of interest and coded into a database. Review findings: The vast majority of eligible articles related to the presence of MMS (96.2%), while just 5.8% considered decommissioning. Overall, articles mainly considered artificial reefs (51.5% of all articles) but increasingly oil and gas (22%), shipwrecks (15.1%) and offshore wind (13.1%). Studies were distributed globally, but the majority focused on the United States, single countries within Europe, Australia, Brazil, China, and Israel; 25 studies spanned multiple countries. Consequently, the bulk of the studies focused on the North Atlantic (incl. Gulf of Mexico, North Sea, and Mediterranean Sea) and North Pacific Oceans. A further 12 studies had a global scope. Studies in majority reported on fish (53%) and invertebrates (41%), and were disproportionately focused on biological (81%) and ecological (48%) impacts. Physico-chemical (13%), habitat (7%), socio-cultural (7%), economic (4%) and functional (8%) outcomes have received less attention. The number of decommissioning studies has been increasing since ca. 2012 but remains noticeably low. Studies mostly focus on oil and gas infrastructures in the USA (Gulf of Mexico) and Northern Europe (North Sea), covering 9 different decommissioning options. Conclusions: This systematic map, the first of its kind, reveals a substantial body of peer-reviewed evidence relating to the presence of MMS in the sea and their impacts, but with considerable bias toward biological and ecological outcomes over abiotic and socio-economic outcomes. The map reveals extremely limited direct evidence of decommissioning effects, likely driven at least in part by international policy preventing consideration of a range of decommissioning options beyond complete removal. Despite evidence of MMS impacts continuing to grow exponentially since the early 1970s, this map reveals key gaps in evidence to support best practice in developing decommissioning options that consider environmental, social and economic effects. Relevant evidence is required to generate greater understanding in those areas and ensure decommissioning options deliver optimal ecosystem outcomes

A global meta-analysis of ecological effects from offshore marine artificial structures

AbstractMarine artificial structures (MAS), including oil and gas installations (O&amp;G) and offshore wind farms (OWFs), have a finite operational period. Selecting the most suitable decommissioning options when reaching end-of-life remains a challenge, in part because their effects are still largely undetermined. Whether decommissioned structures could act (sensu ‘function’) as artificial reefs (ARs) and provide desired ecological benefits is of particular interest. Here we use a meta-analysis approach of 531 effect sizes from 109 articles to assess the ecological effects of MAS, comparing O&amp;G and OWFs to shipwrecks and ARs, with a view to inform their decommissioning. This synthesis demonstrates that while MAS can bring ecological benefits, important idiosyncrasies exist, with differences emerging between MAS types, habitat types, taxa and ecological metrics. Notably, we find limited conclusive evidence that O&amp;G and OWFs would provide significant ecological benefits if decommissioned as ARs. We conclude that decommissioning options aimed at repurposing MAS into ARs may not provide the intended benefits.</jats:p

Practical issues affecting the utility of field survey data for biodiversity monitoring

There is growing emphasis on monitoring biodiversity in European waters not least due to the EC’s recent Marine Strategy Framework Directive (MSFD) listing biodiversity as one descriptor of ‘Good Environmental Status’ (GES). Member States already have various monitoring surveys in place, in particular groundfish and other fisheries surveys, which may provide a cost-effective way of assessing some elements of biodiversity. The MSFD recognises the “need to ensure, as far as possible, compatibility with existing programmes”. Although existing field surveys are a potential source of quantitative data for examining spatial and temporal biodiversity patterns, it must be acknowledged that such surveys were often not originally designed to monitor ‘biodiversity’, and long-term surveys may have had changes in survey design at some point, and/or subtle changes in survey protocols over time. Field surveys for infauna and plankton typically collect and preserve samples at sea, and subsequent laboratory work includes the use of reference collections, quality assurance and longer-term sample storage. Surveys with towed gears can collect large amounts of complex biological material which is typically processed at sea, and so different forms of quality assurance are required. The taxonomic knowledge, experience and enthusiasm of sea-going staff can also influence the biodiversity information collected (e.g. time spent sorting complex catches, species identification). Hence, matrices of species-station data can contain ‘artefacts’ that need to be understood and addressed before deriving biodiversity metrics, and may even necessitate some degree of data filtering. This paper uses field data from selected surveys to illustrate how various factors can affect ‘biodiversity information’

Evidence for the effects of decommissioning man-made structures on marine ecosystems globally: a systematic map

Background: Many marine man-made structures (MMS), such as oil and gas platforms or offshore wind turbines, are nearing their ‘end-of-life’ and require decommissioning. Limited understanding of MMS decommissioning effects currently restricts the consideration of alternative management possibilities, often leaving complete removal as the only option in certain parts of the world. This evidence-base describes the ecosystem effects of marine MMS whilst in place and following cessation of operations, with a view to informing decision-making related to their potential decommissioning. Method: The protocol used to create this map was published a priori. Systematic searches of published, literature in English were conducted using three bibliographic databases, ten specialist organisational websites or repositories, and one search engine, up to early 2021. A total of 15,697 unique articles were identified as potentially relevant to our research questions, of which 2,230 were screened at the full-text level. Of that subset, 860 articles met all pre-defined eligibility criteria. A further 119 articles were identified through “snowballing” of references from literature reviews. The final database consists of 979 articles. For each article included, metadata were extracted for key variables of interest and coded into a database. Review findings: The vast majority of eligible articles related to the presence of MMS (96.2%), while just 5.8% considered decommissioning. Overall, articles mainly considered artificial reefs (51.5% of all articles) but increasingly oil and gas (22%), shipwrecks (15.1%) and offshore wind (13.1%). Studies were distributed globally, but the majority focused on the United States, single countries within Europe, Australia, Brazil, China, and Israel; 25 studies spanned multiple countries. Consequently, the bulk of the studies focused on the North Atlantic (incl. Gulf of Mexico, North Sea, and Mediterranean Sea) and North Pacific Oceans. A further 12 studies had a global scope. Studies in majority reported on fish (53%) and invertebrates (41%), and were disproportionately focused on biological (81%) and ecological (48%) impacts. Physico-chemical (13%), habitat (7%), socio-cultural (7%), economic (4%) and functional (8%) outcomes have received less attention. The number of decommissioning studies has been increasing since ca. 2012 but remains noticeably low. Studies mostly focus on oil and gas infrastructures in the USA (Gulf of Mexico) and Northern Europe (North Sea), covering 9 different decommissioning options. Conclusions: This systematic map, the first of its kind, reveals a substantial body of peer-reviewed evidence relating to the presence of MMS in the sea and their impacts, but with considerable bias toward biological and ecological outcomes over abiotic and socio-economic outcomes. The map reveals extremely limited direct evidence of decommissioning effects, likely driven at least in part by international policy preventing consideration of a range of decommissioning options beyond complete removal. Despite evidence of MMS impacts continuing to grow exponentially since the early 1970s, this map reveals key gaps in evidence to support best practice in developing decommissioning options that consider environmental, social and economic effects. Relevant evidence is required to generate greater understanding in those areas and ensure decommissioning options deliver optimal ecosystem outcomes