Humans benefit from, indeed rely on, what nature provides. As outlined in the Introduction the overarching concept in respect of benefits to humans from the world’s stocks of natural assets, including geology, soil, air, water and all living things, is that of ‘natural capital’. This encompasses the habitats and ecosystems that provide social, environmental and economic benefits to humans and includes the ocean which is fundamental to life on Earth. The specific functions and resources of nature that provide benefits for people are called ‘ecosystem services’ (Figure 1). Some are direct and tangible, such as fish for human consumption or wildlife that give enjoyment when spotted from a beach, clifftop or boat. Others are less tangible, such as the role of some habitats in limiting coastal erosion (sometimes termed a nature-based solution), or how different species and habitats cycle nutrients, breakdown waste, or help mitigate climate change by sequestering and storing carbon and therefore reducing greenhouse gases in the atmosphere. This latter aspect of ecosystem services is placed in the ‘Regulating’ category (elsewhere this is sometimes termed ‘Maintaining' but throughout SMA2020 ‘Regulating’ is used (Figure 1)).

It is clear that human activities and natural disturbances are having a direct impact upon species and habitats, and can have an indirect impact upon species and habitats via changes to the physical or chemical aspects of the marine environment. These changes can influence the biological, and in some cases, economic productivity of an area. For example, the introduction of organic contaminants or excess nutrients can have a significant impact on the biology as well as the appearance and other sensory stimuli experienced by people when visiting the coast, their senses having an effect on how they perceive the sea. This can diminish their feelings of enjoyment and well-being. These features are described in brief below. More information can be accessed by clicking on the relevant tiles at the bottom of the page.

The physical (e.g. temperature range) and chemical (e.g. salinity, dissolved oxygen concentration, dissolved organic carbon, aragonite saturation*) characteristics of the sea underpin the viability, distribution and functioning of species and habitats, and therefore the ecosystem services to which they contribute. The ocean also plays a fundamental role in the cycling of carbon. Climate change and ocean acidification, together with the exploitation of many of the natural resources, currently exert a detrimental influence on these characteristics. This will increase in future and have an impact on the benefits provided by the seas around Scotland unless measures are taken to reverse the changes that are currently being observed. As an example, shell dissolution has been observed in planktonic gastropod larvae collected from the Marine Scotland sampling site off Stonehaven, north-east Scotland (Figure 2). This was due to a decrease in the aragonite saturation. The future impact of this on food webs remains unknown. However, disruption to the carbon cycle in coastal ecosystems is of concern because of the disproportionately high rates of primary production in coastal ecosystems compared with offshore regions.

Anthropogenic sources of contamination (synthetic organic chemicals, heavy metals, plastics), nutrient imbalance, or noise, can have an impact on the physical health, behaviour and functioning of marine species and habitats. Monitoring of both the concentrations of contaminants and their biological effects continues in the seas. See Clean and safe theme. Significant improvements have been observed over time following developments in on-land processes. However, many species, habitats and physical processes also have important roles in processing, detoxifying and protecting the ecosystem which in turn protects people from the negative impacts. Reductions in emissions, discharges and accidental losses of all types of contaminants, together with an improved understanding in the consequences of impulsive and continuous noise, should deliver cleaner and safer seas in which marine life can thrive, increasing the potential for ecotourism. Generally, the concentrations of contaminants in the seas around Scotland are below those where biological effects will be observed. However, there remain some problem areas.

Marine biodiversity benefits from seas that are clean, healthy, safe and able to function naturally. In turn, species and habitats (and the processes that support them) play an essential role in maintaining ecosystem health, helping to mitigate potentially damaging impacts, and providing people with many financial, cultural and health benefits. Nature-based solutions, that provide sustainable mechanisms to ensure healthy and biologically diverse seas, are integral to future planning and climate-change adaptation. Furthermore, flood protection by coastal ecosystem creation and restoration can provide a more sustainable, cost-effective and ecologically sound alternative to conventional coastal engineering. In Scotland, coastal protection against rising sea levels includes managing and conserving coastal wetlands. Healthy seas also play a vital role in trapping and absorbing carbon dioxide. The seagrass meadows, kelp forests, maerl beds, reefs and intertidal saltmarshes all contribute to trapping carbon while the surficial sediments (top 10 cm) of the mapped area covered by SMA2020 contains an estimated 1,515 ± 252 Megatonnes carbon (Smeaton, Austin & Turrell, 2020).