The environmental sensitivity of animals was revealed to me many years ago. I was once asked to find out the amount of sediment that could stop penguins from feeding underwater. We went to areas with and without penguins and recorded visibility using a device called a Secchi disk. Lowered into the water, it’s a black and white circle and when you can no longer see it, you record that as the distance. Simple.
It turns out, Secchi disks exceed the sensitivity of most modern technical equipment. After determining the threshold feeding concentration an engineer exclaimed “nonsense, we can’t even measure this”.
Penguins are ambush predators and appear out of the murk to pounce on unsuspecting fish. Their behaviour is acutely related to their surroundings. We can’t measure such minute sediment concentrations using the most technically-advanced equipment but that doesn’t matter. It only takes a tiny amount of sediment to fog up penguin vision.
The very subtle way animals are connected to their environment translates into far greater effects than we imagine. This idea resurfaced a few days ago when I was reading about frigatebirds on Nauru and their connection to the island’s traditional owners and culture. I’ll come back to that shortly.
The subtlety of animal impact
I have recently spent some time on Phillip Island in Victoria, Australia. The island is a fox-free haven for wildlife, so Cape Barren Geese numbers have notably increased, along with grazing intensity and droppings. Approaching the world famous Penguin Parade by road, you can see areas covered in guano. Penguins that march from the sea each night cut white-lined highways through the geese’s succulent coastal vegetation.
One of the largest seal colonies in Australia is just offshore. Tidal currents from King Island sweep eastward and skip across several promontories, each divided by a series of bays. Lines of white-water appear where the becalmed bay water meets the fast-flowing ocean currents.
Here is where Humpback Whales gorge mouthfuls of fish. Australasian Gannets form flocks to dive in head-first and pods of dolphins cavort around the mouths of these giants. An eternal line of Shy AlbatrossShy Albatross are a signal of ocean health and breed on sub-Antarctic islands. Their population has halved in the last 35 years More shear into view one end, disappearing into the horizon at the other. This species does laps of western Bass Strait from its breeding colony near King Island.
These highways, like on land, are defined by nutrientsEnergy and nutrients are the same thing. Plants capture energy from the Sun and store it in chemicals, via the process of photosynthesis. The excess greenery and waste that plants create, contain chemicals that animals can eat, in order to build their own bodies and reproduce. When a chemical is used this way, we call it a nutrient. As we More but the quantity is almost undetectable to us.
How poor nutrients create the richest diversity
Too much nutrientA substance that contains the raw materials for life. At a chemical level, these are contained inside compounds that are absorbed into the body and essential energy-containing molecules are extracted, so that energy can be transformed into other chemical processes that use the energy for living. More (energy) upsets any system. The most diverse and stable ecosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other animals) can persist and live alongside each other for the longest time possible. Ecosystems are fuelled by the energy created by plants (primary producers) that convert the Sun's heat energy More are nutrient poor.
The only reason we can usually see what’s happening, is because of the environmental sensitivity of animals, their abundance and diversity. Rain immediately washes surplus nutrients deposited by geese, penguins and other animals, into the sea. Fish quickly consume this. In fact, every bit of ocean nutrient is quickly absorbed by sea life.
I’m convinced the line of animals that extends east from Phillip Island, follows a nutrient corridor. Some of this emanates from the seal colony, plus the island’s recovering ecology. There is also the upwelling west of King Island. This nutrient effect drifts many kilometres east, dragged along that invisible current line outside the bays.
For 20 years, Humpback Whales have increased in number from a few thousand to 35,000 on the east coast. We never used to see them feeding here. Now, they are consuming and recycling nutrients, reintroducing trace elements into the water at millions-of-times greater concentration. The richest ecosystems can only exist when there are animals plentiful-enough to amplifyAmplification (of nutrients and energy). Animals consume plants and other animals and in doing so, reintroduce important energy-containing nutrients back into the environment, at even higher concentrations and in patches. Amplification of energy is driven by migration and happens at every scale, from insects moving daily in and out of your vegetable patch, to African wildebeest herds and the seasonal More and concentrate nutrients and build a food chainA single thread in a food web illustrating the chain of animals that eat each other. At the base of the food chain are small high-energy (fast metabolism) animals and at the other end large low metabolism animals. An example would be whales eating krill that eat plankton that eat algae. Or lions that eat gazelles that eat grass. More.
This is ‘rewilding’ on an ocean scale and it’s happening in plain sight.
Phillip Island’s geese, now unperturbed by voracious predators, are doing the same on land. They graze in patterns, creating structural diversity. They don’t so much deliver surplus nutrients, as increase its patchiness and promote greater turnover in important places. These marine geese are fulfilling the role of seabirds in the Arctic and might even be promoting rainfall like they do. The environment has certainly become visibly healthier, more robust and richer for it.
Seabirds create resilience on temperate reefs
These processes set the scene for an explosion in the environmental sensitivity of animals. By reducing how much surplus nutrient there is to measure, animals make ecosystems richer. So, we shouldn’t be surprised when we can’t detect this, other than to see animals thriving.
There is a popular marine park and snorkelling spot at Ricketts Point near Melbourne. This has almost certainly survived destruction by sea urchins, because it’s a seabird roost. Nearby, I’ve snorkelled among small groves of sponges and seaweed, full of seahorses, mycid shrimp and nudibranchs. The only thing that separates these sites from surrounding ‘urchin-barrens’, is the presence of roosting seabirds.
The white glow of guano, dripping down rocks, is just enough but not too much. It entices other animals, swinging the diversity in favour of a more balanced system.
As far as I know, no-one has considered the vital role this plays in the bay’s healthy ecosystems. Notably, almost all the penguins that breed in their thousands on Phillip Island, enter Port Phillip Bay in the winter. The impact on the bay’s ecosystems must be huge. A lively coastal economy would have to depend on it.
The ancestral role of seabirds in community survival
Which brings me back to Nauru.
The Australian Broadcasting Corporation ran a news item about the island’s fishermen claiming they have a ‘hobby’ of catching frigatebirds.
Catching these birds is an ancestral tradition that might date back tens of thousands of years. Locals lure them in with fish, put them in cages and tame them. Then they send them back out to sea where they meet other birds and bring the interlopers back to the island. Killing frigatebirds is taboo and villages with the greatest number perched in front, once had highest standing in the community.
Villages with more birds would have enjoyed greater fish bounty and survived more. So, the tradition of bird-catching became firmly embedded in their culture as a result. We now know, that islands with healthy seabird colonies have more fish.
So, there is a direct link between human health and seabird abundance. The effect, albeit subtle, multiplied over thousands of generations, becomes a significant driver for our survival. The tiny island nation of Nauru in the western Pacific became the second-wealthiest country in the world from mining its guano deposits.
Measurement and management
There is a saying I often hear in science. It goes “if you can’t measure it, you can’t manage it”.
There are two problems with that statement that I now realise. The first is that you can’t manage nature, you can only manage your behaviour within nature. The second is that you can’t always measure nature either. In actual fact, now I come to think of it, there is nothing in that statement that makes any sense. And it might go a long way to explaining why engineers can’t wrap their heads around animal impactWhat is Animal Impact? Without wildlife, Earth would not be habitable for humans, because it's animals that stabilise ecosystems. It’s a fundamental law of nature that animals (and humans) exist because we are the most likely lifeforms to minimise environmental chaos. Animal impact, therefore, is a measure of how much all wildlife is collectively responsible for creating a habitable Earth. The More.
The first nations people of Nauru didn’t employ scientists to decide that frigatebirds were important. Even if they’d wanted to, no scientist can prove this, because the connection between human survival, frigatebirds, nutrients and fish abundance is subtle and timeless. Any short-term study would be unlikely to to find a conclusive connection.
Nowadays it would be almost impossible. Mining caused the loss of traditional culture and bird life decades ago. For an understanding of how nature functions, we can’t just rely on science alone.
I sometimes wish more people could see the world like this. Being able to read nature by watching animals is one of the most extraordinary things you can ever learn. This is why conservationWhy is animal conservation important? Animal conservation is important, because animals are the only mechanism to create biodiversity, which is the mechanism that creates a habitable planet for humans. Without animals, the energy from today’s plants (algae, trees, flowers etc) will eventually reach the atmosphere and ocean, much of it as carbon. The quantity of this plant-based waste is so More is so important. The environmental sensitivity of animals is extraordinary. It’s both the reason we have ecosystems and how we can understand them.
