Blue Planet 2 | Episode 6 | Coasts

Rough seas in Cornwall, UK. Coastlines are dynamic and high energy environments. Photo by Thomas Daguerre of Hydro Motion Media.

We have a tendency to take our coastlines for granted. It is by far the most accessible and relatable marine habitat, with thousands flocking there every day for their primary source of food, watersports, or just to relax. The UN estimates 40% of the world’s population live in coastal areas. They provide the most extensive economic and social benefits of any natural habitat, encompassing 77% of the services provided to us by all ecosystems. It is where most of us began our love for the sea. In the UK, you are never more than 70 miles away from it. Yet it is easy to forget it is a place of extremes, and as important as any other marine habitat.

A GoPro video grab from a maerl bed in the Fal Estuary Special Area of Conservation, for another field course. Who says the UK doesn’t have reefs worth diving in?

Coastal species have to endure excruciating changes in their environment twice a day. Marine animals can be categorised based on their preferences and adaptability to two primary conditions: temperature and salinity (‘saltiness’). A change in salt might be nothing to one of us as we are osmoregulators (we regulate our internal environment) – for an osmoconformer, like a sea cucumber or starfish, this can be devastating. Too little salt, and your internal water diffuses out, and too much, and outside water will pass in until your cells burst. In the ocean, these conditions remain relatively stable – you can assume that they are unlikely to change dramatically in the next few metres, or few hours. However, if you live in the intertidal zone, you are likely to be bombarded with really hot temperatures at low tide, dramatic changes in salinity if you live in an estuary or at a river mouth, and running out of oxygen if you are caught in a rockpool. To make matters worse, the coast itself is constantly shifting, as shown in the programme. You have to be very hardy and resilient to live here.

Me on a beach in Spain
A Mediterranean coastline in Bolonia, Spain on a University field course. Local marine fauna we saw from a reef survey include Holothurians (sea cucumbers), Decapods (crabs), Cephalopods (octopus and squid), and various Bivalves (clams).

Coastal management is a huge challenge anywhere in the world – there is always a trade off between using the coastline for economic and recreational ventures, but not at the sacrifice of the coast’s ecology and longevity. Although only covering 20% of the Earth’s surface, 41% of the world’s population are coastal inhabitants. For example Guyana, a country larger than the UK, 90% of its population lives on a narrow coastal plane, and only a narrow sea wall protects its inhabitants from the ocean. 21 of the world’s 33 megacities are found on the coast, including Tokyo, Lagos, New York and Buenos Aires. With a globally increasing population, how do we ensure coastlines are sustainably developed and not overxploited?

I have noticed that the UK’s coastlines are a severely underrated habitat among many wildlife enthusiasts. Since the establishment of Lundy Island as the first MCZ (Marine Conservation Zone) in January 2010, a total of 50 sites now make up an area the same size as Wales. These are designated to protect rare and threatened species, and also the wide diversity of life found here. We were lucky enough to conduct some camera drop surveys of the maerl beds of the Fal Special Area of Conservation – a red calcareous algae, superficially similar to corals – of which the UK has in several locations. Maerl can be up to 8000 years old, and provide habitat for rare species like Couch’s goby, much like coral reefs do in the tropics. Additionally mudflats, estuaries and sandbanks are not the most glamorous marine habitats but have still been highlighted for conservation as part of global efforts to conserve biodiversity. Just as an example to the importance of this Blue Belt initiative, seagulls are a red list species in the UK due to their overall declines across the country due to habitat loss. This will come as a surprise to many. They are widely considered pests as they have been increasing in urban areas, partly because of abundant food, and partly because they have nowhere else to go.

Appreciating and conserving the marine environment does not just encompass tropical coral reefs, the great whales of the open ocean and the polar ice caps that many of us will only ever admire through a screen. Declines in biodiversity are all-encompassing and are essential for the future of habitats, and ultimately, our own wellbeing. We in the UK are just as responsible for protecting our marine species as any other country, and you don’t have to fly to the tropics to be close to the Blue Planet.

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