Tuesday, June 17, 2014

Silent Springs

Pause for a second and picture water… what do you see?

Visually, water is tremendously diverse: it can be pure white in the form of snow capping a mountain, deep blue as seen in the open ocean, or brown like the great Mississippi. It may boast the magical azure hue of the Caribbean or take on the brilliant oranges, reds, and pinks of the sky at dawn. But what is perhaps the most beautiful and mesmerizing is when it simply has no color at all - this is when it truly feels like you can fly.

In the clear water of Ichetucknee Blue Hole, you can make out the distant green treetops in the sky - it truly feels like you can fly.
Water also moves in incredible ways. Salty water ebbs and flows predictably under the influence of the moon, while rivers wander and pulse like beating hearts as they are fed by and then starved of rain and meltwater. In the chilly poles, water is bound as ice - seemingly motionless in its solid state but very vulnerable to a return to its fluid form with warming. Artesian springs flow from below while drops of rain careen from the clouds above.

Listening to the symphony of rain while underwater is one of my favorite sounds.
And it is these mesmerizing movements that create an addicting melody. A love for the ocean makes us long for the relaxing sound of waves on the shore, and flowing water calms the anxious soul, just like the pitter-patter of rain on a lazy Sunday afternoon. We can hear streams babble and waterfalls roar: while water is not silent, it has no voice. When it emerges from its mysterious passageways hidden beneath our feet, water has a story to tell. But in order to fully understand its language, we must do much more than listen with our ears.

Visually, we can tell a lot by looking at water. Here, clear/green spring water from Devil's Ear and Eye at Ginnie Springs mixes with tannic water from the Santa Fe River. As the sun shines through the mixing waters, it creates a beautiful reddish glow overhead.
Water’s story is often visual – over time, it may change color or begin to flow more slowly. What once fell as crystal clear raindrops can become dark brown as it picks up tannic acids from the leaves and organic matter surrounding a river, staining the water like tea; this is what colors the tea-brown tannic waters of the Santa Fe and Suwannee Rivers. Clear blue lakes can turn green when cyanobacteria bloom (1), and crystal clear springs can become choked with algae, as seen in Florida. While these visual clues are both telling and compelling, water also holds fascinating messages that we cannot see.
More compelling visual clues that there is something wrong with our water. Domination by the cyanophyte Lyngbya wollei near the natural well at Silver Glen Spring in January 2014.
Part of unlocking water’s story involves figuring out what nutrients are present. The results of lab tests run on a sample of water collected in the field can tell us how much nitrogen, phosphorus, calcium (and a whole slough of micronutrients, metals, etc.), are present in the water (see chart below). Because water quality has been measured at many sites throughout Florida for many years, we can compare current values to those measured in the past and piece together a picture of how the water has been changing over time (2).

An example of  water quality parameters that are measured in the field and in the lab (from Springs of Florida, Bulletin 66 - see the DEP website for a full copy of this document).
Another fascinating story bound up in water molecules requires different tools to decipher. Similar to the way trees hide their age deep within the rings of their trunks and fish hide their age in the rings of their ear bones (called “otoliths”)(3), water carries information that helps us unlock its approximate age. By measuring isotopes and chemical tracers, scientists can determine water's average age, which helps them answer the question of whether water emanating from a spring vent is rain that percolated through the ground from a storm the week before or water that is just now emerging after 50-100+ years underground. Similar techniques allow scientists to identify sources of pollution in the water and, for example, understand whether nitrate pollution in a given spring came from fertilizer or sewage (4).

Finally, what I personally find most fascinating is that we can measure how a river “breathes” (5). Scientists are like river doctors – but instead of using a stethoscope, we use sondes, devices capable of measuring dissolved oxygen (DO), pH, temperature, etc. over time. Measuring DO over time, allows us to calculate gross primary productivity and (along with other values) ecosystem metabolism (6). In addition, relatively new sensors (called SUNAs) allow us to measure nitrate levels over time as well, which helps us better understand how nitrogen uptake may vary depending on which plants and animals are present in a given spring ecosystem.

(Top) The main spring at Gum Slough. The dark colors underwater are massive beds of algae. (Bottom) Courtney and I have been working on a project at Gum Slough since fall 2013 that combines both of our interests: ecosystem metabolism/nitrate dynamics and grazers. Our two main questions are (a.) do increased densities of grazers influence levels of gross primary production and (b.) how do metabolism and nitrate uptake vary according to the type of vegetation present in the spring?
The ability to measure dissolved oxygen, nitrates, and flow over time has allowed scientists to demonstrate that our spring ecosystems have not been stable over time and that many are being degraded to an algae-dominated state (7).

(For a more comprehensive review of the science, you can watch this video that I made last semester:)

Algal Proliferation in Florida's Springs from Jenny Adler on Vimeo.

Final project for Algae Biology and Ecology, Spring 2014. A scientific literature review of the diverse array of factors leading to algal proliferation in Florida's iconic freshwater springs. Narrated Keynote presentation (all photos and videos in this presentation are by jenniferadlerphotography.com).

In short, our springs are threatened - those who understand the springs’ struggles and those who rely on and love water must be the voice of our springs. WE together must be the voice of our springs, because we all depend upon the same aquifer that feeds the springs. Our silent springs are crying for help, but their voice is not being heard, and ignoring their quiet message is only making them more silent over time – their once-powerful flows are being diminished and water that used to flow swiftly through spring runs is becoming quiet as well (8). Where crystal clear water once told a joyful story, tinted water and algae abounds. Water flowing from the springs today tells us a story about the present, and it also suggests what may be in store in the future; without change, there is no fairytale ending. But if we work together, the voice of the springs will be loud and clear, just like the water of our springs once was.

Fairytale in Blue Spring, Gilchrist County. A Suwannee cooter (Pseudemys concinna suwanniensis) takes a breath in the endless underwater world. Where the spring meets the sky, it extends to infinity, unlike our water supply.


(1) More information about (and pictures of) harmful cyanobacteria blooms can be found on the EPA website. Also, if you google "cyanobacteria bloom", you will see what I mean about the intense green color of the water.

(2) While nutrient levels have been increasing over time, Heffernan et al. (2010) demonstrate in the graph below that nitrate levels are not necessarily correlated with percent algal cover. For more information, see the video above - I explain more of the science background and research in the video. 
(3) For some neat information about dendrochronologists, see: http://ltrr.arizona.edu/about/treerings and for more info about otoliths and aging fish, see: http://myfwc.com/research/saltwater/fish/age-growth-lab/aging-fish-otoliths/

(4) The science behind aging groundwater and determining the source of pollution can be complex and often times leads to inconclusive results. For an in-depth explanation, see this USGS webpage or Katz 2004.

(5) For more information and an interview with Dr. Matt Cohen, see this cool article in the Environmental Monitor from 2012.

(6) Basic info on stream metabolism is on Wikipedia. There are also many scientific papers on whole ecosystem and stream metabolism - if you're interested, I'm happy to pass some along. Most that I've learned about GPP and metabolism comes from Courtney :)

(7) Heffernan et al. (2010). Algal blooms and the nitrogen-enrichment hypothesis in Florida springs: evidence, alternatives, and adaptive management. Ecological Applications 20 (3): 816-829.

(8) Figure from a 2013 Wetland Solutions Inc. report demonstrating that the annual average discharge at Rainbow and Silver Springs has been declining since the 1950s.

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