Keystone species are so called because they have a disproportionately large effect on the environment relative to their abundance.
One famous example is the wolves of Yellowstone National Park who, on their reintroduction in 1995, created a domino effect that eventually resulted in rivers within the park changing their course. The wolves achieved this through predating grazing animals, which in turn took pressure off young trees and helped kickstart the recovery of a lost forest. The forest then grew up along rivers that in some cases changed course.
But keystone species don’t always have to be apex predators, they can also be ones which physically create habitats in which hundreds of other animals and plants can play out their lives. The humble seaweeds known commonly as kelp are such species. Their keystone role is so important that, last week, Sir David Attenborough spoke out on the need to protect kelp from the industrial-scale harvesting proposed in Scotland’s inshore waters. Sir David was unequivocal in his statement that the dredging proposals are a “wholly short-sighted measure that risks the wholesale devastation of our kelp beds”.
Kelp forms underwater ‘forests’ that provide food and shelter for myriad marine life including sea squirts, anemones, molluscs, worms, brittlestars, prawns, soft corals, sponges, amphipods and fish such as lumpsuckers, saithe, pollock and wrasse. They also provide us with an array of benefits by sequestering and storing carbon, providing breeding grounds for commercially important fish and protecting coasts from storm damage. Remove kelp and we remove an entire living ecosystem – hence Sir David’s unusually forthright appeal.
The kelp harvesting proposal has been made by the Ayr-based company Marine Biopolymers, who wish to dredge 30,000 tonnes of kelp a year along Scotland’s west coast. Harvested kelp is valuable for processing into a carbohydrate called aginate, used in variety of different products from salad dressings and ice cream to shampoo, toothpaste, and pharmaceuticals.
Consultations on the proposal are ongoing but Green MSP Mark Ruskell successfully amended the Scottish Crown Estate Bill during the second stage of its current passage through parliament with a clause that effectively bans harvesting techniques that prevent plants from re-growing. If this amendment survives stage three of the Bill, it may well render the Marine Biopolymers proposal redundant. Many would celebrate such an outcome, not least those who have businesses that depend on healthy coastal ecosystems, including those who gather kelp using sustainable, hand-harvesting techniques.
The kelp drama illustrates perfectly the new contract we need to negotiate with our natural environment if we are to have a sustainable, prosperous future. On the one hand, we have a proposal which could plunder a valuable resource, leaving it so damaged that its future value will be lost. This is exactly what happened with Scotland’s herring fishery, which from a peak of 250 million barrels in 1907 collapsed to nothing by the 1970s. Alternatively we can look after the vital stocks of natural capital within our kelp forests and seek instead to realise the dividends these stocks will provide if managed responsibly. Some of that value might be direct financial flows, for example from products manufactured from hand harvesting. Some of that value will be less obvious but even more vital, such as natural coastal defences, carbon storage and protection of breeding grounds from which we derive world-beating, nutritious seafood.
The kelp debate is a chance to show we can shift from a model of plunder to a model of stewardship in our marine environment. Let’s make that move.
Jonny Hughes is Chief Executive of the Scottish Wildlife Trust. Follow him on Twitter @JonnyEcology.