Something to marvel at
This is another of those mailings from eco-justice ministries. I was in awe....
An easier-to-read version with paragraphs is at http://www.eco-justice.org/E-060804.asp
The astounding complexity of natural systems gives ample opportunities fordelight, wonder and humility to those who are willing and able to look deeply.When we glimpse some of the ways that the multiple parts of a system fittogether and interact, we're able to grow in our understanding that the"things" around us are almost never isolated, disconnected things, but areinstead members of a dynamic and fragile community.A report that I read this week provided a jaw-dropping example of theunimagined interconnectedness of God's creation. Not only does this new pieceof news stretch our intellect and move us to awe, it provides a vivid warningabout the dangers of tampering with the world around us.
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The August, 2006 issue of Scientific American has an article about "The Fish &the Forest." The title sells the story short, though, by not naming a thirdessential player in the account -- bears. But let's start with the fish.Many of us are at least vaguely aware of the life cycle of Pacific salmon.Salmon eggs hatch in freshwater streams, and the tiny little fishies go withthe flow downhill to reach the ocean. Eventually, the salmon reach the sea andspend anywhere from one to four years swimming in the salt water of the ocean,growing strong and fat. Then, in one of the great wonders of migration, the adult fish leave the ocean and return to same freshwater stream where they were born. There, they spawn, starting the cycle of life once again.Or some of them do. Not all of the young fish make it to the ocean, and thefish swimming in the sea may fall prey to fishing nets or predation. Only asmall percentage of the hatchlings ever begin the journey back upstream tobreed.The amazing new research that I read about this week is concerned with thatremnant which makes the return trip to the streams of their birth. Inparticular, it deals with the large number of fish which get, oh, so close totheir goal, but die before they reach the gravel beds where they would laytheir eggs. That is where it gets both complicated and fascinating.Out of the multitudes of salmon swimming upstream, many are caught and killedby bears. The bears -- needing to fatten themselves for months of hibernation-- have voracious appetites, and are remarkably skillful at scooping migratingsalmon from the rivers. In the Alaskan streams that were studied, anywhere from30 to 60 percent of the migrating fish were killed by bears. That's a lot offish.Because the bears are such good fishers -- some can routinely snag a fish inless than a minute -- they're not very motivated to eat every bit of thesalmon. Indeed, the bears only chow down on the fattiest, most nutritional bitsof the fish, and discard the rest.The bears, though, don't generally drop the chewed up carcass right back intothe river. Bears compete among each other for the fish -- even the mostsuccessful fishers find that it is easier to steal somebody else's big, fatsalmon than to catch their own. To avoid fights over a fish, a bear will leavethe stream with its meal and wander a short distance into the forest beforetaking a few bites of salmon flesh, and then discarding the rest.This creates a surprising situation where the bodies of thousands of fish arescattered far away from the rushing water of a salmon stream. Many otheranimals have a field day with this bounteous carrion. More than 50 species ofvertebrates including gulls, ravens, eagles, foxes and mink, and also amultitude of insects, feed on the dead fish. The larger of these scavengerswill often move the fish even farther from the stream.What a surprise! Bears eating salmon provide a feast for a diverse collectionof animals, some of which never even come close to the water. Those animals, inturn, provide nourishment for an expanding food web. In fact, there are moreinsect-eating songbirds along streams with salmon, because the dead fishincrease the populations of bugs.But there is still more to this remarkable story.The salmon which have grown to adulthood in the ocean and fought their wayupstream to the spawning grounds carry within themselves high concentrations ofimportant nutrients -- calcium, phosphorus and nitrogen -- as well as fats andproteins which fatten the bears and birds. While we would normally expectminerals and energy to flow downhill, migrating salmon bring food calories andfertilizer uphill in substantial quantities.In the soils typical of northern forests, plant growth is often limited bynitrogen or phosphorus -- two of the nutrients that are spread into the forestswhen the bears drop fish away from the stream. The study revealed that up to70% of the nitrogen in the foliage of streamside shrubs and trees is of salmonorigin. The growth of Sitka spruce, a dominant stream-side tree, was three timegreater along salmon streams than near streams without salmon. The trees thrivebecause of fishy fertilizer.Who could have imagined it? There are healthy forests far from the Pacificbecause of the key minerals that salmon carry upstream from the sea, and thatbears carry to dry land.
+ + + + +
It doesn't take much to break this astonishing cycle. Obviously, ifover-fishing or insurmountable dams cut the number of migrating salmon, theescalator of energy and nutrients can't run uphill. If the bear population isreduced, the spawning fish will die in the water, and all of the nutrients willwash back downstream. If deforestation comes right to the edge of the stream(as many clear-cuts do), there won't be a mix of predators to spread theminerals as widely.Until just a few years ago, no one had any idea about the ways in whichmigrating salmon carried nutrients from the ocean to the mountains. Dams werebuilt, fishing quotas set, and forest management plans developed without anyawareness of the role of fish in maintaining forest health. Now, forestersscatter salmon carcasses near streams that the salmon can't reach, becausethey've learned how important the fish are to the forest.This new research opens our eyes to one of the great wonders of thisintricately interconnected world. And it should provide a warning to us aboutinflicting change on natural systems, for we may not know -- and we may neverbe able to predict -- how the changes we bring will alter complex ecologicalsystems.Salmon feed the forests! Thanks be to God for this remarkable way of keepingthe world in balance. May our sense of wonder help us learn to be very gentlein the ways we disrupt such remarkable systems.NOTE: The Scientific American article is available on-line athttp://scientificamerican.com/article.cfm?chanID=sa006&articleID=000C6B0F-B1A0-14C0-B04F83414B7F0000&pageNumber=1&catID=2
Shalom!
Peter Sawtell
Executive Director, Eco-Justice Ministries
400 S Williams St, Denver, CO 80209
An easier-to-read version with paragraphs is at http://www.eco-justice.org/E-060804.asp
The astounding complexity of natural systems gives ample opportunities fordelight, wonder and humility to those who are willing and able to look deeply.When we glimpse some of the ways that the multiple parts of a system fittogether and interact, we're able to grow in our understanding that the"things" around us are almost never isolated, disconnected things, but areinstead members of a dynamic and fragile community.A report that I read this week provided a jaw-dropping example of theunimagined interconnectedness of God's creation. Not only does this new pieceof news stretch our intellect and move us to awe, it provides a vivid warningabout the dangers of tampering with the world around us.
+ + + + +
The August, 2006 issue of Scientific American has an article about "The Fish &the Forest." The title sells the story short, though, by not naming a thirdessential player in the account -- bears. But let's start with the fish.Many of us are at least vaguely aware of the life cycle of Pacific salmon.Salmon eggs hatch in freshwater streams, and the tiny little fishies go withthe flow downhill to reach the ocean. Eventually, the salmon reach the sea andspend anywhere from one to four years swimming in the salt water of the ocean,growing strong and fat. Then, in one of the great wonders of migration, the adult fish leave the ocean and return to same freshwater stream where they were born. There, they spawn, starting the cycle of life once again.Or some of them do. Not all of the young fish make it to the ocean, and thefish swimming in the sea may fall prey to fishing nets or predation. Only asmall percentage of the hatchlings ever begin the journey back upstream tobreed.The amazing new research that I read about this week is concerned with thatremnant which makes the return trip to the streams of their birth. Inparticular, it deals with the large number of fish which get, oh, so close totheir goal, but die before they reach the gravel beds where they would laytheir eggs. That is where it gets both complicated and fascinating.Out of the multitudes of salmon swimming upstream, many are caught and killedby bears. The bears -- needing to fatten themselves for months of hibernation-- have voracious appetites, and are remarkably skillful at scooping migratingsalmon from the rivers. In the Alaskan streams that were studied, anywhere from30 to 60 percent of the migrating fish were killed by bears. That's a lot offish.Because the bears are such good fishers -- some can routinely snag a fish inless than a minute -- they're not very motivated to eat every bit of thesalmon. Indeed, the bears only chow down on the fattiest, most nutritional bitsof the fish, and discard the rest.The bears, though, don't generally drop the chewed up carcass right back intothe river. Bears compete among each other for the fish -- even the mostsuccessful fishers find that it is easier to steal somebody else's big, fatsalmon than to catch their own. To avoid fights over a fish, a bear will leavethe stream with its meal and wander a short distance into the forest beforetaking a few bites of salmon flesh, and then discarding the rest.This creates a surprising situation where the bodies of thousands of fish arescattered far away from the rushing water of a salmon stream. Many otheranimals have a field day with this bounteous carrion. More than 50 species ofvertebrates including gulls, ravens, eagles, foxes and mink, and also amultitude of insects, feed on the dead fish. The larger of these scavengerswill often move the fish even farther from the stream.What a surprise! Bears eating salmon provide a feast for a diverse collectionof animals, some of which never even come close to the water. Those animals, inturn, provide nourishment for an expanding food web. In fact, there are moreinsect-eating songbirds along streams with salmon, because the dead fishincrease the populations of bugs.But there is still more to this remarkable story.The salmon which have grown to adulthood in the ocean and fought their wayupstream to the spawning grounds carry within themselves high concentrations ofimportant nutrients -- calcium, phosphorus and nitrogen -- as well as fats andproteins which fatten the bears and birds. While we would normally expectminerals and energy to flow downhill, migrating salmon bring food calories andfertilizer uphill in substantial quantities.In the soils typical of northern forests, plant growth is often limited bynitrogen or phosphorus -- two of the nutrients that are spread into the forestswhen the bears drop fish away from the stream. The study revealed that up to70% of the nitrogen in the foliage of streamside shrubs and trees is of salmonorigin. The growth of Sitka spruce, a dominant stream-side tree, was three timegreater along salmon streams than near streams without salmon. The trees thrivebecause of fishy fertilizer.Who could have imagined it? There are healthy forests far from the Pacificbecause of the key minerals that salmon carry upstream from the sea, and thatbears carry to dry land.
+ + + + +
It doesn't take much to break this astonishing cycle. Obviously, ifover-fishing or insurmountable dams cut the number of migrating salmon, theescalator of energy and nutrients can't run uphill. If the bear population isreduced, the spawning fish will die in the water, and all of the nutrients willwash back downstream. If deforestation comes right to the edge of the stream(as many clear-cuts do), there won't be a mix of predators to spread theminerals as widely.Until just a few years ago, no one had any idea about the ways in whichmigrating salmon carried nutrients from the ocean to the mountains. Dams werebuilt, fishing quotas set, and forest management plans developed without anyawareness of the role of fish in maintaining forest health. Now, forestersscatter salmon carcasses near streams that the salmon can't reach, becausethey've learned how important the fish are to the forest.This new research opens our eyes to one of the great wonders of thisintricately interconnected world. And it should provide a warning to us aboutinflicting change on natural systems, for we may not know -- and we may neverbe able to predict -- how the changes we bring will alter complex ecologicalsystems.Salmon feed the forests! Thanks be to God for this remarkable way of keepingthe world in balance. May our sense of wonder help us learn to be very gentlein the ways we disrupt such remarkable systems.NOTE: The Scientific American article is available on-line athttp://scientificamerican.com/article.cfm?chanID=sa006&articleID=000C6B0F-B1A0-14C0-B04F83414B7F0000&pageNumber=1&catID=2
Shalom!
Peter Sawtell
Executive Director, Eco-Justice Ministries
400 S Williams St, Denver, CO 80209
posted by MSMAR @ 5:48 AM
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