Freshwater Fish: The Miner’s Canary in the Aquatic Realm.
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An interview with evolutionary biologist, Melanie Stiassny, Associate Curator, Department of Ichthyology, American Museum of Natural History, 1995. Dr. Stiassy’s research focuses on the systemics of fresh water and fauna in Madagascar and Africa. Her interests include conservation biology of freshwater fish and she is a member of the museum’s current bio-diversity initiative in Tanzania.
I found Dr. Melanie Stiassny in her office in the cavernous corridors inside New York’s Museum of Natural History. It is a large spacious room and yellow sunlight streams in through the large ornate windows across her large untidy desk. Huge stuffed fish hang from the walls with charts and anatomical drawings. There’s a Walkman on her desk and a pair of yellow roller blades tossed in one corner – she blades around Central Park at lunchtime.
“My specialty is fish so I’m an ictholologist and have really grown to love fish tremendously. They are a fabulous model to examine evolutionary principles. They are an incredibly important indicator organism that tells you the health of aquatic systems. In my case I work primarily with freshwater fish which are like the miner’s canary in the aquatic realm. You can learn about the health of fresh water by understanding what’s happening to fish that live in fresh water.”
“Take this aquarium here – its housing two very interesting residents that have become pets to me – they are very rare species called Parotalatier Polanai – cyclic fish, from Madagascar.”
She goes on field trips to Madagascar, an enormous island in the Indian Ocean off the coast of Mozambique on the east-central African coast. It’s the fourth largest island in the world.
“Historically Madagascar has been isolated in the Indian Ocean for about 60 million years. It broke off Africa at about the same time India did - about 180 million years ago. It drifted into its present position about 120 million years ago.
India broke off between 80 and 60 million years and opened up the Indian ocean and pushed up the Himalayas so the end result of this story is that Madagascar is this enormous island that has been in isolation for all these millions of years, all the organisms that you find on that island – both the plants and the animals.
"Madagascar has been likened to a naturalist wonderland – it’s a place where evolution has just gone on its own and it’s a place that provides very special insights into the evolutionary process. Its also a place that in recent times – when I say recent I mean the last 2,000 years - which is when we think people first came to Madagascar - since then we’ve seen the most incredible perturbations and degradations of its land and forests – rain forests and dry forests. It's undergone the most extreme environmental pressure as people have cleared the land basically to graze cattle, clear land for growing rice so cattle and rice are really what people of the island are most interested in eating."
How blue is our planet?
"We are familiar with those satellite images of earth and we see “the blue planet” but it should be called “the water planet". Three-quarters of the planet is covered with water but 97.5 percent is marine salt water. Just 2.5 percent is actually fresh water.
"If you took a bottle of coke to represent the earth’s water, probably three of four cap fulls may represents the amount of fresh water on the planet. But its much more dire than that because most of that fresh water isn’t available for humans, animals, agriculture and industry.
"Sixty-nine percent of fresh water has been locked in the solar poles until recently. Of course now the poles are melting into the sea so we are losing fresh water this way.
The hydrological cycle.
“But I want to make a quick point about that because what we really have to bear in mind when we start talking about how we are going to sustain that tiny amount of water – really what we need to be talking about is the rate at which fresh water is replenished on the planet through the hydrological cycle coming down as rain and snow and being recycled – that’s the water we dip into to use.”
"The water cycle, technically known as the hydrologic cycle, is the continuous circulation of water in our hydrosphere and is driven by solar radiation. It includes our atmosphere, man’s and surface water, groundwater. As water moves through the cycle it changes state between liquid, solid and gas. It moves form “compartment” to “compartment” as rivers down to the oceans and by physical processes of evaporation, precipitation, infiltration, runoff, sub- surface flow. The movement of water within this cycle is the subject of hydrology.
“Some people have said that if the world’s water could fit in a bath tub, the portion that could be used sustainably in any given year is less than one-teaspoon. That teaspoon of water is all we’ve got to support human populations, agriculture and industry plus all the water needed to sustain the natural water.
"That teaspoon of available fresh water is the same size today as it was 2,000 years ago when the planet’s population was about three-percent of the current size. So we are still dipping into the same teaspoon and we will continue dipping into the future.
"Since 1940 the world population has doubled and water consumption has quadrupled. We need to irrigate more and more land to produce enough food to support the rising population and frankly, we are very quickly reaching the upper limits of sustainability – water is fast becoming a limiting factor.”
The main drain on water is in agricultural systems, irrigation and industry. Domestic usage is really a very small component.
“One of the indices used to look at the so called development of a nation or a region is to look at how much of water usage is industrial and how much agricultural – generally about two-thirds of all water is for agriculture, mainly irrigation. About twenty-three percent is for industry, leaving eight percent for domestic use and of course these numbers vary tremendously in different regions.
"So the state of water is precarious. I large proportion of our fresh water is underground in aquifers and some are very deep and actually contain fossil water that’s been there for a very long time – perhaps thousands of years of storage. Pulling this water out of the ground is unsustainable. We are killing the goose that laid the golden egg – it’s a very short-term perspective – we’ve begun to plunder subterranean water reserves.
Concentration of species in fresh water.
"I am a specialist in fish so I t end to look at things from a fish’s perspective. Of the 22,000 species of fishes alive on the planet today, about half are found in fresh water. That means nearly half of all living species of fish actually live in less than one-hundredth of a percent (.001%) of the earth’s water. That’s a tremendous concentration of biodiversity.
"Put another way – fish comprise nearly half of all vertebrates alive on the planet today – animals with backbones. When you add them all together you have about half on land and half in water. Half of all living vertebrates are fish. Therefore I can rephrase that statistic about concentrations of species in water.
"We have about 44,000 known species of vertebrates on the planet including fish. So about one-quarter of all vertebrate bio-diversity is concentrated into less than one-hundredth of one percent (.001%) of earth’s water. And it’s not just fish, it’s all the other organism essential to life in water too.
"We think of the sea as being so tremendously rich and in many respects it is. But in terms of actual living numbers of plants and animals its been estimated that on a percentage basis, fresh water is probably about sixty times richer. So we are talking about a fantastically rich biological medium and ecosystem in fresh water systems.
"The other aspect of fresh water that I think make it so vulnerable is simply you can look at these fresh waters of the world – these lakes and rivers, just like islands – I mean they make a perfect analogy – instead of being islands of land surrounded by water, these are islands of water surrounded by land and just like all of the animals that live on islands – their vulnerable because if something happens there is no escape – its exactly the same in fresh water. We are talking about extremely vulnerable habitats and that’s exactly what we see in our environment as we cut down forests, alter water flow patterns in rivers and lakes, we build dams, we divert for irrigation – all of those changes have a tremendous cascading effect on the animals living in those water systems. Bottom line is that there is no way out – there is sea at one end and land at the other.”
Wetlands
“What we have done to wetlands throughout the globe is quiet tragic. Over a period of about 200 years, the lower 48 states have lost more than half of their original wetlands mainly through drainage to provide land for agriculture. That’s like losing 60 acres of wetlands for every hour that passed since the
US was established.
"There is a tendency to look at swamps and marshes as prime candidates to be drained and turned into pasture but wetlands are far more valuable than pasture. It is estimated that 60 percent of the world’s total stream flow is regulated. And here is one last sorry statistic: there was a nationwide river inventory in the U.S. which estimated that of more than five million kilometers of streams and rivers in the nation, most have been so radically altered that just two-percent are of sufficiently high quality to be worthy of federal protection.
"Its one of those things – you don’t realize what you’ve got until its gone. I think now we are beginning to reach a point where what we’ve lost is really becoming understood and we have a cascading effect through our ecology.
Much of the water overuse is in industry and agriculture. Water is actually subsidized for industry and agriculture. Irrigation systems are inefficient (37% efficient) and are often built and managed by public agencies at minimal charge.
The return on these irrigation programs probably average no more than about ten to twenty percent of the true cost of delivering water.
We need to rethink this false economy.”
How important was the Green Revolution?
“The Green Revolution was tremendously important. To feed our expanding population we’ve had to employ tremendous increase in irrigation – land was reclaimed from desert to be irrigated and farmed. Water provided the crops to feed the growing population. And genetic modification of existing crops produced very high yields but very thirsty crops creating even more demand for water.
Agriculture is the biggest drain on water consumption – it uses more than two-thirds of our supply and it is very inefficient so if we can improve efficiency we can save enormous amounts.
If governments stopped subsidizing and under pricing water it would help a lot. Water costs less in Arizona than it does in Wisconsin. This is a false economy. We need to recycle more water. It’s insane to be tapping into aquifers of pure high quality fossil water and squiring it on the land that will be salinated. We need to redesign agriculture.
They grew cotton around the Aral Sea, a semi-arid region and cotton is one of the thirstiest crops – sugar is the thirstiest. We should not be growing these crops in arid regions. I think we are going to be forced to really start looking at how we are using water and why we are using it in the way we are – why we are subsidizing certain practices in the way we are.
How much is water worth.
Water is worth everything. You can’t have anything without water. Water is central to life
Edges, margins and niches encourage opportunities - and there are many.
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