Catching sight of a whale for the first time is an unforgettable experience; excitement and awe flood our being and mingle with a less tangible emotion, perhaps one of deep connection, love you might say. I felt it when I saw my first whale, a Minke fishing in the tide off the headland of Rubha Hunish on the north tip of Skye. Tom saw it first, a dark expanse followed by a fin that scythed through the water surface. It moved swiftly and sank before I could turn in the seat of my sea kayak to see it. As I waited for it to rise again scanning this way and that, my heart pounded in my ears. With a burst of exhaled air it surfaced not far away; my skin prickled with excitement and I let out a little squeal. It appeared to be doing laps in the tide, drifting for a time then swimming back against the flow to reposition near the headland where the tide was moving fastest. We followed suit for a few rounds then gave thanks to the whale and allowed ourselves to get pushed east by the tide.
I certainly felt the love that day at Rubha Hunish, it poured from me in great waves so that I could not imagine needing anything more from life. But I also feel it when I see a blackbird bathing in a puddle and when sunlight bursts through a cloud igniting all the colours in the landscape. There’s no end to the wonder that the natural world can conjure in me; the more I learn the more I realise that everything is connected and that love arises from this interconnection.
One of the most exciting scientific findings of the last fifty years is the discovery of trophic cascades. The term derives from how ecologists group animals and plants in an ecosystem according to how they feed; each group is assigned a trophic level (the word trophic means food or feeding) so that a food chain develops with predators at the top and herbivores and plants below. Changing the number of animals at the top trophic level can have an effect that cascades down through all trophic levels, impacting every animal and plant that forms a link in the chain.
Research on whales has revealed them to be key predators in the oceans that trigger a classic example of trophic cascade when they become scarce. Whales eat fish and krill so you might expect that killing whales would boost the numbers of fish and krill and therefore the food available for other fishers to eat. But as commercial whaling efforts peaked in the early 20th century and the number of great whales declined so did the numbers of fish and krill. But how can it be that removing a predator causes the numbers of their prey to decrease and not increase as logic would predict? We now know this to be due to the cascading effect caused by removing a key predator from a finely balanced ocean system; scientists have worked out that not only do whales help to keep their prey alive but they help to sustain the entire living system. And it all comes down to two movements, swimming and defecation.
Whales often dive to great depths to feed and as they return they release vast clouds of poo called faecal plumes that are very rich in iron and nitrogen. In fact, scientists working in the Southern Ocean found iron concentrations in whale poo to be 10 million times that of the surrounding Antarctic seawater. All this extra iron and nitrogen fertilizes the plant plankton that thrive in the light saturated surface waters where nutrients are scarce. Productivity is further enhanced by the vertical movements of the whales up and down through the water column which has a mixing effect, returning nutrients and plant plankton back to the surface. It has been estimated that the vertical mixing of water caused by the movement of animals up and down through the oceans is roughly the same as the amount of mixing caused by all the worlds wind, waves and tides. It is an astonishing realisation that many of the oceans larger inhabitants act as ecosystem engineers whose presence help to maintain the health and stability of the world’s oceans.
So where there is more plant plankton there is more animal plankton on which the larger creatures feed-more whales means more fish and krill. But the story does not end there; the plant plankton also absorbs carbon dioxide from the atmosphere. When it eventually dies and sinks to the deep ocean it takes this carbon out of circulation down to a place where it remains for thousands of years. More whales equals more plankton equals more carbon absorption. In their historical heyday, before commercial whaling decimated their numbers, they may have been responsible for removing tens of millions of tonnes of carbon from the atmosphere every year. In a nutshell, whales change the climate.
Until recently large creatures occupying the top trophic level were plentiful and widespread across the globe and had been for millions of years. The loss of these animals may be humankind’s most pervasive influence on the natural world. Yet science has shown that allowing the great whales to recover could reverse some of the damage we have wrought by increasing the productivity of plant plankton. Their role in the functioning of our planet may be vital and we may need to save the whales in order to save ourselves; after all, every second breath we take is produced by the plant plankton of the world’s oceans. I believe compassion and a collective will to change is essential. So if I can inspire a little bit of love, a rising sense of awe for the natural world I am happy. As observed by the great naturalist John Muir “When we try to pick out anything by itself, we find it hitched to everything else in the Universe.” We are as connected to whales as they are to plankton…