Friday, June 27, 2014

Organic Debris Creates Bigger, Fatter Fish

I was alerted to this recent study via Rick Meril who runs the very prolific blog Coyotes, Wolves, and Cougars...... forever! and although I first noticed it a couple of days ago I am just getting around to talking about it today as I find it very pertinent to all things beaver.

Basically what the Cambridge researchers were looking at is the respective importance of organic debris versus algae in terms of fish health. Essentially zooplankton - which is more or less a catch all for various small to microscopic crustaceans, insects, worms, protists, and other invertebrate critters which collectively form the base of aquatic food chains i.e. fish food - can feed upon primary productive pathways or detrital pathways. In plain speak they can feed on water plants, usually algae, or also graze on the bacteria and fungi breaking down plant material - leaves, woody debris. In an elegant example of  the scientific method the researchers were able to control both inputs by looking at watersheds with pristine, old growth forests (lots of organic debris) and watersheds bordering strip-mined and deforested landscapes. Furthermore by analyzing the carbon isotope signatures in fish taken from these waters the scientists were able to trace where the carbon came from because algal carbon is going to bear a different isotope than carbon derived from land plants (forest debris washed into the system). 

While it has long been recognized that terrestrial organic input is an important factor in watershed and fish health, the study is alarming in addressing how important it is.

"We found fish that had almost 70% of their biomass made from carbon that came from trees and leaves instead of aquatic food chain sources," said Dr Andrew Tanentzap from Cambridge's Department of Plant Sciences, and lead author of the new study, published today in the journal Nature Communications.

Ok think about that for a second, 70% of their mass is derived from eating critters that fed off of stuff that was feeding off of dead land plants washed into the river. 

"More than 60% of the world's fresh water is in the boreal areas such as Canada, Scandinavia and large parts of Siberia. These areas are suffering from human disturbance such as logging, mining, and forest fires resulting from climate change -- all occurrences predicted to intensify in coming years," said Tanentzap.
The scientists studied eight different 'watersheds' surrounding the lake: a given area across which all the moisture drains into a single stream. When these fast-moving streams -- full of detritus from forest foliage -- hit the slow-moving lake, the debris falls out of suspension and sinks, forming layers of sediment which create mini deltas.
Debris is broken down by bacteria, which is in turn consumed by zooplankton: tiny translucent creatures that also feed on algae. The fish then feed on the zooplankton. Until recently, algae were believed to be the only source of food for zooplankton, but the new research builds on previous work that showed they also feed on bacteria from forest matter drained into lakes.
The researchers worked along the food chains in the mini deltas. "Where you have more dissolved forest matter you have more bacteria, more bacteria equals more zooplankton; areas with the most zooplankton had the largest 'fattest' fish," said Tanentzap.

Going a little further the authors also suggest such importance of organic debris is important in all freshwater ecosystems from the poles to the tropics.

"While we've only studied boreal regions, these results are likely to bear out globally. Forest loss is damaging aquatic food chains of which many humans are a part."

Ok if you are like me you probably realized that it is easy to substitute beaver ponds for lakes and also substitute the active transport of organic matter by beaver into freshwater systems for the passive natural input. If you accept these intuitive substitutions it becomes logical to suggest beaver activity is bolstering aquatic food chains. 

And here is your bonus google satellite view of beaver dams from Lundy Valley in the eastern Sierra.
I can't believe I never thought to look at beaver dams this way - the satellite views really let you see the large scale landscape transformation that beaver dams achieve!!

Lundy Valley beaver dams, the large dam to right is over 200 feet across!! Google Satellite (c)

Andrew J. Tanentzap, Erik J. Szkokan-Emilson, Brian W. Kielstra, Michael T. Arts, Norman D. Yan, John M. Gunn. Forests fuel fish growth in freshwater deltas.Nature Communications, 2014; 5 DOI: 10.1038/ncomms5077

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Friday, June 20, 2014

"Beavers Used to Be Almost Everywhere in California" Bay Nature

The issue of beaver in California got a booster shot today as it is featured prominently in Bay Nature, the article titles simply Beaver Used to Be Almost Everywhere in California. The backbone of the article is a certain paper recently published in CDFW revamping the historical range of beaver in California. I might have talked about the paper once or twice before. The article very succinctly ties together a lot of the main points of contention that the paper grapples with. From the "fur desert" perpetrated by the Hudson Bay Company to the lack of knowledge that Grinnel and Tapp had to contend with, if you are new to the issue of beaver in California this article does a great job of introducing the topic to you. I must also commend the author of the article Alison Hawkes for gathering some great quotes from some of the authors of the paper.

Cheryl Reynolds. Worth A Dam
"All of San Jose was a gigantic wetland with tens of thousands of elk and huge flocks of waterfowl that would have darkened the sky."

"We have the least understanding of any state on what used to live here."

Rick Lanman, Institute of Historical Ecology

"I knew this assumption that beaver were never in the Bay Area was bogus just from life experience. There was a beaver right under I-680 when I would drive home. I knew they were there."

Heidi Perryman, Martinez Beavers/Worth a Dam

I want to concentrate on this next quote by Brock Dolman of the Water Institute at Occidental College as it pertains directly to the question of beavers at the limit of their range in coastal California, namely southern California.

"We felt the missing piece was that beaver were never as numerous (as otters) and a group of native folks set on capturing them wouldn't take long in eradicating them, especially in riparian systems where there is not a lot of room to move."

Now I think this quote really contains a lot of good stuff but I think it might go over a lot of people's heads. First off we should clarify that otter refers to sea otter, and they roamed all the way down into Baja. And they were ruthlessly hunted for their pelts by fur trappers. Once the sea otters started getting low in number trappers looked at what else was around. By supplying native Americans with steel traps, the wary and elusive beaver - normally a difficult quarry - was now an easy and reliable source of fur to trade with the Europeans. Now with this in mind we must remind ourselves that coastal California, especially getting into southern California, never had the water and therefore the population of beavers that areas like the delta or wetter parts of the continent had. Each watershed may have had very low or even ephemeral populations of beavers even before trapping commenced. It is entirely possible that beaver would become locally extinct in a watershed and then reestablished several times over even without human interference. There was in all probability a waxing and waning of beaver populations at the limits of their range, becoming more pronounced into southern California. Keep in mind that even without human intervention California has seen some serious droughts in the not so distant past - which by themselves limited beaver populations in California.

Jaguar in southern California painting by Laura Cunningham

I also think, when discussing beaver at the limits of their range. it useful to talk about jaguar in California. Yes jaguar ranged perhaps as far north as the Bay area historically. If you do some Internet sleuthing you will come across records of jaguar in Palm Springs and Monterey, California. But jaguar were rare  here in California even before European colonization. They were at the northern limit of their range. In all probability jaguar sporadically made it further up into the Pacific Northwest or Rocky mountains. But we will probably never find good records of them there as they were exceedingly rare even in the best of times. Likewise even in areas where they maintained populations we may never see records of them there. I think a similar situation is going on with the spotty record of beaver on the coast especially in southern California. They were never that common to begin with.

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Wednesday, June 11, 2014

River Restoration... If You Want It

For this post I want to concentrate on several positive stories on river restoration. One does not have to look far these days to be pummeled into a state of angry depression. So only good new today.  Beaver are just one piece of the puzzle with regards to watershed health. I would offer the most important factor in watershed health/river restoration in compromised ecosystems is the still daunting task of increasing public awareness and interest in healthy rivers.

For any seemingly insurmountable challenge an invisible tipping point exists. Where the shackles that bind us to social inertia, inaction, and pragmatic pessimism,  are quickly stripped away and revealed for what they are: human constructs. What mankind has created, mankind can destroy.

"A couple of decades ago it was radical in terms of thinking you can take a dam out... unthinkable... the conversation has changed."

Last week I was very fortunate and blessed to see a screening of a very important, compelling, and timely film: Damnation. It was all you can hope for in terms of making a profound argument for letting the rivers of America run free and wild. I will not attempt to summarize or recap the points the film made you should just go see it for yourself.

What was especially important to me with regards to this film was that a key dam featured in the film, a noted dead beat dam, is Matilija dam of Ventura county. Matilija creek is a steelhead creek and the dam serves zero purpose what so ever being completely silted in. Patagonia, a company based in Ventura, produced and screened the film at their yard and have long championed removal of the dam. 

From tearing down dams to building small ones (the beaver variety of course!!). Make sure you check out and support the Beaver Believers with a taxable donation for their kickstarter. I just donated 25$, i would have loved to have donated more but I am a wage slave... But my 25$ gets me on the wall, gets me stickers, a digital download of the film and a beaver believers shot glass!! Awesome!! 23 days to go to reach the extended goal of 12,000$!! Good job believers!!!

"Water is one of the most sacred, magical, and powerful gifts that we have ever been given, and we need to remember that because we have forgotten it."

"If we can put beaver back in the majority of the streams where they used to be is exactly what we should be doing."

Films such as these, and the powerful messages behind them, offer hope that a new dawn is rising with regards to our attitude towards the lands we live on and the wild beings we share the earth with. It is important to remind ourselves that every journey begins with the first step and that 
the darkest hour is just before dawn.

Steve Nash. Oxnard CA

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