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Crowded seas are becoming a pressing management problem with the increased development of offshore renewable energy (ORE) to combat climate change. Marine ecosystems are complex and varied; therefore, we need new tools to help rapidly increase our understanding of how they are likely to change with both climate and anthropogenic changes. This study uses a pragmatic data‐driven Bayesian network approach to capture the patterns of ecosystem complexity and reveal trends of ecosystem drivers (i.e. indicators) important to ecosystem functioning across space and over time. The ecosystem approach assessed physical and biological indicators and their influence on population (abundance/productivity) trends in four regions with contrasting habitats of the North Sea within the last 30 years (1990–2019). What‐if scenarios were conducted to examine species/functional group responses to physical (temperature and stratification) representing climate and large‐scale ORE development effects, as well as anthropogenic (fishing) changes. Clear patterns were revealed, including temporal trends of the dynamic nature of bottom‐up effects driven by physical change versus top‐down effects driven by fishing across trophic levels and habitat types. All four regions are influenced by both effects; however, the dominance of effects was dependent on region: Shetland and Orkney (bottom‐up driven), southern North Sea (top‐down driven). In general, regions with stronger bottom‐up effects showed increasing population trends whereas those with stronger top‐down effects, decreasing trends. Our findings also suggest that some species are much better indicators of either bottom‐up (e.g. zooplankton), top‐down effects (e.g. fish) or both (e.g. grey seal), but the strength of indicator is dependent on habitat type. The habitat‐specific results provide better understanding of what type of ecosystem change they are indicating (physical or biophysical) and therefore indicators that assess both ecosystem status and resilience, ensuring a more strategic and integrated evaluation of trade‐offs for future sustainable management of our shallow seas. [ABSTRACT FROM AUTHOR]

Tidal energy is a rapidly developing area of the marine renewable energy sector that requires converters to be placed within areas of fast current speeds to be commercially viable. Tidal environments are also utilised by marine fauna (marine mammals, seabirds and fish) for foraging purposes, with usage patterns observed at fine spatiotemporal scales (seconds and metres). An overlap between tidal developments and fauna creates uncertainty regarding the environmental impact of converters. Due to the limited number of tidal energy converters in operation, there is inadequate knowledge of marine megafaunal usage of tidal stream environments, especially the collection of fine-scale empirical evidence required to inform on and predict potential environmental effects. This review details the suitability of using multirotor unmanned aerial vehicles within tidal stream environments as a tool for capturing fine-scale biophysical interactions. This includes presenting the advantages and disadvantages of use, highlighting complementary image processing and automation techniques, and showcasing the limited current examples of usage within tidal stream environments. These considerations help to demonstrate the appropriateness of unmanned aerial vehicles, alongside applicable image processing, for use as a survey tool to further quantify the potential environmental impacts of marine renewable energy developments. [ABSTRACT FROM AUTHOR]

Primary production dynamics are strongly associated with vertical density profiles, which dictate the depth of stratification and mixed layers. Climate change and artificial structures (e.g. windfarms) are likely to modify the strength of stratification and vertical distribution of nutrient fluxes, especially in shelf seas where fine scale processes are important drivers, affecting the vertical distribution of phytoplankton. To understand the effect of physical changes on primary production, identifying the linkage between density and phytoplankton profiles is essential. Here, the ecological relevance of eight density layers (DLs) obtained by multiple methods that define three different portions of the pycnocline (above, centre, below) was evaluated to identify a valuable proxy for subsurface Chlorophyll-a (Chl-a mg m-3) concentrations. The associations of subsurface Chl-a with surface and deep mixing were investigated by hypothesizing the occurrence at the same depth of any DL and the maximum Chl-a layer (DMC) using Spearman correlation, linear regression, and a Major Axis analysis. Out of 1237 observations of the water column exhibiting a pycnocline, 78% reported DMCs above the bottom mixed layer depth (BMLD). This suggests that the BMLD is a boundary trapping Chl-a in shallow waters (≤ 120 m). BMLD constantly described Chl-a vertical distribution despite surface mixing indicators, suggesting a significant contribution of deep mixing processes in supporting subsurface production under specific conditions (e.g. prolonged stratification, tidal cycle, and bathymetry). Using BMLD for defining subsurface Chl-a could be a valuable tool for understanding the spatiotemporal variability of Chl-a in shelf seas, representing a potential variable for ecological assessments. [ABSTRACT FROM AUTHOR]

The transition of plants and animals from sea to land required adaptation to a very different physical and chemical environment. In this paper, we focus on the consequences of the differences between the magnitude of the variability of ocean and atmospheric dynamics, with the ocean environment (in particular temperature and currents) being two to three orders of magnitude less variable than that on land. We suggest that greater insights on possible responses of marine vs. terrestrial systems to rapid climate change can be gained by considering that terrestrial vertebrates, invertebrates and plants have evolved from marine organisms that, pre-Cambrian, had early life history developmental stages as planktonic larvae. Marine larvae were/are adapted to the predictable and minimal range of temperature changes and regularities in ocean currents, as most organisms utilize the energy in these currents as an "auxiliary" source for predictable gamete and larvae dispersal. Post-Cambrian, on land, no such simple strategy was available; instead, most terrestrial organisms have evolved reproductive strategies and behaviours to eliminate, or at least minimize, the consequences of much larger atmospheric variability. Adapting our future use of these systems sensibly will require greater understanding of how the two regimes respond to rapid climate change. [ABSTRACT FROM AUTHOR]