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Sea lice are a persistent threat in many areas where salmon farming is practised. In common with the management of disease, infection levels are typically controlled by operating sites within distinct geographical areas, allowing for coordinated treatment and fallow cycles. However, the hydrodynamic connectivity and consequent transmission of lice larvae between sites is often not well understood, which limits our ability to optimise the spatial distribution of farms to minimise infection. We used a multistage modelling approach to investigate the transmission of sea lice larvae between salmon aquaculture sites in Loch Fyne, Scotland. A finite element hydrodynamic model was forced using meteorological data collected over the study period. Output from this model was used to drive a particle-tracking model. The latter model implemented the development and mortality of larvae to estimate the probability of successful larval dispersal between sites. In turn, these dispersal probabilities were used to define a network describing the sea lice metapopulation (its habitat defined by the aquaculture sites). Methods from graph theory allow the identification of those sites in the network that are likely to be key for the control of sea lice in the loch population as a whole. Model outputs were compared with data from a campaign of plankton tows and with lice abundance data from aquaculture sites. The general pattern of abundance was reasonably well replicated, albeit with some notable discrepancies. These differences are worth investigating further, as they may be suggestive of sources of infection by wild fish or of inadequacies in the model.

Summary1. Offshore renewable energy provides an increasing component of our electricity supply. We have limited understanding of the potential environmental impacts of these developments, particularly in the move to larger scales. Surfaces provided by devices offer novel habitat to marine organisms, which may allow species to spread to new areas. 2. We used coupled biological and hydrodynamic models to investigate the spread of intertidal marine organisms with pelagic larvae (such as barnacles or gastropods) in the region around south-western Scotland. We assessed the impact of novel habitat on dispersal and its role in allowing transgression of physical barriers. 3. Model renewable energy device sites provided habitat for pelagic larval particles that would otherwise have been lost offshore. They also provided a source of larvae for existing coastal sites. 4. Many offshore devices fulfilled source and destination (or intermediate connection) roles, creating new dispersal pathways, and allowing previously impossible northward dispersal from the Northern Irish coast to Scotland. 5. Synthesis and applications. New habitat close to biogeographical barriers has implications for existing species' distributions and genetic population structure. It also affects the spread of non-native species and 'climate migrants'. Monitoring these sites for the presence of such species will be important in determining the future ecology of coastal habitat and in maintaining economic aquaculture and marina operations. Future model studies should focus on particular species of importance, taking account of their biology and current distribution.

Tree species differ from one another in, and display trade-offs among, a wide range of attributes, including canopy and understorey growth and mortality rates, fecundity, height and crown allometry, and crown transmissivity. But how does this variation affect the outcome of interspecific competition and hence community structure? We derive criteria for the outcome of competition among tree species competing for light, given their allometric and life-history parameters. These criteria are defined in terms of a new simple whole life-cycle measure of performance, which provides a simple way to organize and understand the many ways in which species differ. The general case, in which all parameters can differ between species, can produce coexistence, founder control or competitive exclusion: thus, competition for light need not be hierarchical as implied by R Ã theory. The special case in which species differ only in crown transmissivity produces neutral dynamics. The special case in which species differ in all parameters except crown transmissivity gives hierarchical competition, where the equivalent of R Ã isẐ Ã , the height at which trees enter the canopy in an equilibrium monoculture.

In studies of the population dynamics of parasitic sea lice and the implications of outbreaks for salmon farms, several types of mathematical models have been implemented. Delay differential equation models describe the temporal dynamics of average adult lice densities over many farm sites. In contrast, larval transport models consider the relative densities of lice at farm sites by modelling larval movements between them but do not account for temporal dynamics or feedbacks created by reproduction. Finally, several recent studies have investigated spatiotemporal variation in site lice abundances using statistical models and distance-based proxies for connectivity. We developed a model which integrates connectivity estimates from larval transport models into the delay differential equation framework. This allows representation of sea lice developmental stages, dispersal between sites, and the impact of management actions. Even with identical external infection rates, lice abundances differ dramatically between farms over a production cycle (dependent on oceanographic conditions and resulting between-farm connectivity). Once infected, lice dynamics are dominated by site reproduction and subsequent dispersal. Lice control decreases actual lice abundances and also reduces variation in abundance between sites (within each simulation) and between simulation runs. Control at sites with the highest magnitude of incoming connections, computed directly from connectivity modelling, had the greatest impact on lice abundances across all sites. Connectivity metrics may therefore be a reasonable approximation of the effectiveness of management practices at particular sites. However, the model also provides new opportunities for investigation and prediction of lice abundances in interconnected systems with spatially varying infection and management.

Citation for published item:rossinD wd rwr nd ogueD rh tF nd renhrdD viz nd n yudenhovenD elexnder F iF nd shourneD grlEvenne nd wuiruriD ivlyne F nd omzykD eleksndr wF nd qr¡ %EvlorenteD wrin nd rleD hel nd reviD iolet nd edmsD om nd vllliD veil nd he fellD i¢ n nd yeD wrin nd esendeD pernndo @PHIVA 9sdentifying future reserh diretions for iodiversityD eosystem servies nd sustinility X perspetives from erlyEreer reserhersF9D snterntionl journl of sustinle development world eologyFD PS @QAF ppF PRWEPTIF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTWe aimed to identify priority research questions in the field of biodiversity, ecosystem services and sustainability (BESS), based on a workshop held during the NRG BESS Conference for Early Career Researchers on BESS, and to compare these to existing horizon scanning exercises. This work highlights the need for improved data availability through collaboration and knowledge exchange, which, in turn, can support the integrated valuation and sustainable management of ecosystems in response to global change. In addition, clear connectivity among different research themes in this field further emphasizes the need to consider a wider range of topics simultaneously to ensure the sustainable management of ecosystems for human wellbeing. In contrast to other horizon scanning exercises, our focus was more interdisciplinary and more concerned with the limits of sustainability and dynamic relationships between social and ecological systems. The identified questions could provide a framework for researchers, policy makers, funding agencies and the private sector to advance knowledge in biodiversity and ES research and to develop and implement policies to enable sustainable future development. ARTICLE HISTORY

In modern large-scale salmon aquaculture, sites are managed within spatial units. In Scottish waters, several different definitions are used: operator-defined 'Farm Management Areas' (FMAs), regulator-defined 'Disease Management Areas' (DMAs) and 'Fish Health Management Reporting areas' (FHMRAs). FMAs balance many operational requirements, while the sole purpose of DMAs is to limit the spread of disease. FHMRAs are based on historical wild fish monitoring areas. One objective of these units is to monitor and limit the spread of water-borne agents such as infectious salmon anaemia and parasites such as sea lice, which present a perennial economic and ecological challenge. However, unit boundaries are either based on simplified hydrodynamic assumptions, or do not incorporate such information. Their effectiveness for infection control is therefore unclear. We used the latest developments in hydrodynamic modelling to predict population connectivity of sea lice between all current operational salmon aquaculture sites in the complex west coast of Scotland region over 1 yr (June 2013 to June 2014). Aggregating site connectivity matrices by management units, we identified the extent to which units supplied lice to (or received lice from) other units, and their effectiveness for infection control. Total estimated connectivity varied over time by a factor of 2. A general northward movement of simulated larvae was observed. Even the smallest management units reduced external infection by around 75% versus individually managed sites. Larger management units reduced estimated connectivity further. Optimised units derived by applying thresholds to site matrices suggested that management within water bodies at the scale of 50 to 100 km would be most effective.

Offshore aquaculture has gained momentum in recent years, and the production of an increasing number of marine fish species is being relocated offshore. Initially, predictions of the advantages that offshore aquaculture would present over nearshore farming were made without enough science‐based evidence. Now, with more scientific knowledge, this review revisits past predictions and expectations of offshore aquaculture. We analysed and explained the oceanographic features that define offshore and nearshore sites. Using Atlantic salmon (Salmo salar) as a case study, we focussed on sea lice, amoebic gill disease, and the risk of harmful algal blooms, as well as the direct effects of the oceanography on the health and physiology of fish. The operational and licencing challenges and advantages of offshore aquaculture are also considered. The lack of space in increasingly saturated sheltered areas will push new farms out to offshore locations and, if appropriate steps are followed, offshore aquaculture can be successful. Firstly, the physical capabilities of the farmed fish species and infrastructure must be fully understood. Secondly, the oceanography of potential sites must be carefully studied to confirm that they are compatible with the species‐specific capabilities. And, thirdly, an economic plan considering the operational costs and licencing limitations of the site must be developed. This review will serve as a guide and a compilation of information for researchers and stakeholders.