Cultivation of kelp has been well established throughout Asia, and there is now growing interest in the cultivation of macroalgae in Europe to meet future resource needs. If this industry is to become established throughout Europe, then balancing the associated environmental risks with potential benefits will be necessary to ensure the carrying capacity of the receiving environments are not exceeded and conservation objects are not undermined. This is a systematic review of the ecosystem changes likely to be associated with a developing seaweed aquaculture industry. Monitoring recommendations are made by risk ranking environmental changes, highlighting the current knowledge gaps and providing research priorities to address them. Environmental changes of greatest concern were identified to include: facilitation of disease, alteration of population genetics and wider alterations to the local physiochemical environment. Current high levels of uncertainty surrounding the true extent of some environmental changes mean conservative risk rankings are given. Recommended monitoring options are discussed that aim to address uncertainty and facilitate informed decision-making. Whilst current small-scale cultivation projects are considered 'low risk,' an expansion of the industry that includes 'large-scale' cultivation will necessitate a more complete understanding of the scale dependent changes in order to balance environmental risks with the benefits that seaweed cultivation projects can offer.

Increasing concerns over global climate change and sustainable fuel procurement are driving the search for new ways to derive energy from the seas. Globally, the offshore wind energy sector has progressed rapidly, and wave and tidal‐current energy converters are now approaching deployment at commercial scales. To date, most studies of the ecological effects of marine renewable energy development have concentrated on birds and marine mammals. Here, we focus on the consequences for benthic flora and fauna, and for benthic habitats across a variety of scales. We use a “Benthic Footprint” concept to discuss the potential for species‐specific environmental responses, and to consider the poorly understood cumulative effects of wind, wave, and tidal‐current energy operations on marine ecosystems. Collaborations between ecologists, industry specialists, and government bodies, as well as better designs for devices, arrays, and developments consisting of multiple arrays, can contribute to the goal of reducing the Benthic Footprint of marine renewable energy, thereby facilitating large‐scale implementation of these technologies.

All marine species studied thus far show rhythmic temporal patterns in their behavioural, physiological, and molecular functions, which are collectively known as biological rhythms. Biological rhythms are generated by biological clocks that time biological functions and are synchronised by geophysical cycles such as the solar lightdark cycle and tidal cycle. On continental margins, behavioural rhythms can be detected by diel (i.e., 24-h based) or seasonal periodical trawling as a consequence of massive inward and outward displacements of populations to and from the sample areas. As a result, significant errors in population/stock and biodiversity assessments performed by trawling may occur if timing of sampling is not taken into account. The increasing number of cabled and permanent multiparametric seafloor observatories now allows direct, continuous, and long-lasting monitoring of benthic ecosystems and analysis in relation to several habitat cycles. This review describes the adaptation of this technology to investigations of rhythmic behaviour by focusing on automated videoimaging. Diel fluctuations in the number of video-observed individuals can be used as a measure of average population rhythmic behaviour. The potential implementation of automated video image analysis in relation to animal tracking and classification procedures based on the combined use of morphometric tools and multivariate statistics is detailed in relation to populational and community studies. Based on video cameras mounted at multiparametric cabled observatories, an integrated time-series analysis protocol using chrono-biomedical procedures is proposed to place video-recorded bioinformation in an oceanographic context.

Knowledge of biofouling typical of marine structures is essential for engineers to define appropriate loading criteria in addition to informing other stakeholders about the ecological implications of creating novel artificial environments. There is a lack of information regarding biofouling community composition (including weight and density characteristics) on floating structures associated with future marine renewable energy generation technologies. A network of navigation buoys were identified across a range of geographical areas, environmental conditions (tidal flow speed, temperature and salinity), and deployment durations suitable for future developments. Despite the perceived importance of environmental and temporal factors, geographical location explained the greatest proportion of the observed variation in community composition, emphasising the importance of considering geography when assessing the impact of biofouling on device functioning and associated ecology. The principal taxa associated with variation in biofouling community composition were mussels (Mytilus edulis), which were also important when determining loading criteria.

The phaeophyte macroalga Saccharina latissima is gaining economic importance as an aquaculture crop. To decrease costs associated with the hatchery, the time required for meiospores to develop into sporophytes ready for outplanting must be minimised and survivorship maximised. The settlement and juvenile development of S. latissima was examined in a series of experimental manipulations. It was determined that (1) Meiospore settlement should be conducted in the dark in nutrient-enriched medium.(2) Continued nutrient enrichment in the hatchery increased growth and survival of the developing sporophytes. (3) It is best to use the diatom inhibitor germanium dioxide only during settlement and the first week of light exposure, rather than continuously or not at all. This treatment leads to the highest survival rate and sporophyte length. (4) Pre-treating the settlement surface with a commercial yeast extract can increase settlement and early development size; however, over-application can be highly detrimental leading to reduced survival, size and patchy growth.