Sunday, November 2, 2014

Salt marsh research on a quiet day in deniersville

Sou | 1:17 PM Go to the first of 2 comments. Add a comment

It's another quiet day at WUWT. Anthony Watts posted a press release about a paper in the journal, Applications in Plant Sciences.

The paper was describing a "microcosm unit with tidal simulation", which was built with plastic buckets, aquarium tubing, dosing pumps and timers. It cost quite a bit less than other simulators, took up around half the space, could be constructed practically anywhere and is a clever low tech solution that does the job.

Fig 1. Tidal simulator microcosm units consisted of one 18.9-L bucket containing a Spartina alterniflora sward connected to a second reservoir bucket (with a lid to prevent evaporation) by aquarium tubing attached to two water-lifting pumps. Pump 1 transferred water from the reservoir into the microcosm, and pump 2 transferred the water from the microcosm back into the reservoir (A). Units were connected to an outdoor timer (3) programmed to create tidal exchange every 6 h (B), and aquarium tubing extended from pumps to the bottom of both the microcosm and reservoir buckets to ensure complete transfer of water between them (C). Source: MacTavish and Cohen 2014

The paper was written by researchers at Georgia Southern University, Rachel MacTavish and Risa Cohen. The paper lists the many benefits (my paras):
Simple construction, low cost, and versatility are major advantages of this tidal simulator over existing systems. Using materials found at hardware and aquarium retailers, each tidal simulation unit was constructed for less than US$27 in approximately 20 min, thus a large number of tidal simulator units can be set up within several days, unlike other large tidal simulation systems that use expensive custom tanks or facilities and can take months to set up. (Gleason et al., 1981; Spaulding and Hester, 2007; Cohen et al., 2009). Each unit also only takes up 0.18 m2 (0.3 × 0.6 m), allowing for high levels of experimental replication in a small space.
Furthermore, S. alterniflora growth in the microcosm tidal simulation system was similar to that of plants exposed to natural tidal regimes; no differences in plant height, stem density, or above- and belowground biomass occurred between tidal treatments, providing ecological relevance to experiments conducted using the simulators. 

The apparatus looks to have been constructed for a Masters thesis project by Rachel MacTavish. The project was investigating the influence of salinity and ammonium concentration on the uptake of nitrogen in  Spartina alterniflora, a salt marsh macrophyte, and on its growth. Turns out that both nitrogen uptake and biomass decrease with increasing salinity, mitigated by increased NH4+.

The Masters project was to gather information to help develop strategies to manage salt marshes. Runoff from agriculture and urban environments into salt marshes increases the inorganic nitrogen. At the same time if fresh water flow into the marshes is reduced (eg diverted for other uses), salinity is increased. If both happen at the same time, the marshes are getting more saline, and have more nitrogen.

The press release about the apparatus states that it will be suited for various practical studies:
"Salt marshes have incredible value, protecting coastal populations from high wave energy during storms, sequestering large amounts of carbon, and serving as nursery habitat for many commercially important fishes," explains MacTavish. "They are extremely productive ecosystems, providing nutrients and organic carbon to nearby coastal waters and beaches."
Oil spills, heavy metals, and other sorts of water pollution continuously threaten tidal ecosystems. This new and simple mechanism to simulate the tide will enable researchers everywhere to uncover solutions to these and other hazards.
"I'm already using [the tidal simulator] in one of my experiments to study the concurrent effects of altered water column ammonium and salinity on S. alterniflora nitrogen uptake," says MacTavish. "Another colleague at Georgia Southern University is also using it to examine the effects of sediment amendments on S. alterniflora growth under different soil organic matter concentrations to improve salt marsh restoration strategies."

From the WUWT comments

I don't know why the press release was featured at WUWT. Anthony made no comment to guide his readers in what they should say about it. Perhaps he just wanted to give WUWT readers some insight into how science is done.

The comments can be sorted into five categories, and came from:
  1. the interested (people who said it was interesting!), 
  2. the illiterati (who are against new knowledge of any kind), 
  3. the uninformed (of the Dunning-Kruger type), 
  4. the silly (of the typical WUWT type), and 
  5. the concerned (that the comments from the previous three categories would make WUWT look bad).

Bill Marsh  - the interested (cat. 1)
November 1, 2014 at 12:50 pm
Very interesting.

nielszoo  - the money-conscious illiterati (cat. 2)
November 1, 2014 at 1:42 pm
Wonderful, I wish her the best of luck but I have a question. Are my taxes paying for this? If so, why? I’m glad she found a less expensive way to do her research but I’m getting tired of working my @ss off at an economically viable job in order to pay for her to play with her science project instead of paying for her own hobby. 

Latitude  - the illiterati (cat. 2)
November 1, 2014 at 12:52 pm
Their results indicated no significant difference…..plants grew the same in a pot
Does the nimwit know there’s thousands of nurserys growing plants for restoration projects already?

jorgekafkazar  - the concerned (aimed at Latitude) (cat. 5)
November 1, 2014 at 1:27 pm
A stupid comment and an unwarranted ad hominem. The simulation of tidal ebb and flow, along with variations in salinity, turbidity, etc., doesn’t happen in “nurserys” (sic). Hence the pumps and tubing. Did you even read the post?
Their method has been validated to some degree: “The new tidal simulator protocol and the comparison of S. alterniflora growth in real tidal conditions versus the simulator are published in the November issue of Applications in Plant Sciences…”

Doc  - the silly (cat. 4)
November 1, 2014 at 1:12 pm
This proves nothing because Al Gore said so. And Barack “Sgt. Schultze” Obama says, “I see nooothiing!”

High Treason   - the silly (cat. 4)
November 1, 2014 at 2:24 pm
Can we put cAGW in the bucket too? Still, cAGW “research” costs even less- 1 penny to be precise. It starts as a thought (a penny for your thoughts) and an hypothesis(that humans…….) and the money gets thrown at you.) 

Alexander Feht  - the uninformed (Dunning-Kruger type) (cat. 3)
November 1, 2014 at 3:55 pm
Why simulate something that you can see and study?
Just to keep your boots dry?
Also, she uses the stupidest possible expression, “organic carbon.”

Warrick  - the concerned (cat. 5)
November 1, 2014 at 2:16 pm
I find it rather sad this almost knee jerk negative reaction. Tidal flat systems are notoriously difficult to set up in a realistic experimental manner. If her system is reasonably close to realistic, as appears to be the case, she then has a wonderful system to apply variations and pose some “what if..?” questions. Tidal flats can be exceptionally productive ecological zones – only to most of us they look better when the tide is in. In many of our coastal systems, these zones have been drained or reclaimed for building. If many of our important commercial fish species start life in these zones, then reducing the fish nursery size must also reduce the number of fish available to be caught later.

Neil Jordan  - the interested (cat. 1)
November 1, 2014 at 2:18 pm
Page 5 of 6 of the paper includes the obligatory genuflection to sea level rise. Otherwise, this paper is a very good example of applied research, something I might want to try at home. The key items left out of the bill of materials in Appendix 1A were the programmable timers. I would anticipate that the $27 cost would increase. However, the authors were able to program their system to replicate semidiurnal tides, so they get a passing grade from me.

Rud Istvan  - the concerned (cat. 5)
November 1, 2014 at 5:40 pm
Not WUWT finest moment. And not commenters most brilliant distinction. Folks, your eagerness to deconstruct everything does you no credit. As here. And harms your general credibility. Badly.

Jon Reinertsen  - added value (uncategorised)
November 1, 2014 at 5:03 pm
The one real world thing the experiment is not replicating is the effect of the tide rushing in and out. All the soil/mud is contained in the buckets, tidal marshes move constantly. Huge quantities of mud/soil are eroded and deposited on an almost daily basis. I lived in Derby, Western Australia for a number of years. The tidal range was up to 11 metres every day. When the tide was out the mudflats stretched for kilometres. By the way, those logs out there, aren’t logs. I also lived in Carnarvon, Western Australia. Fishing in the delta of the Gascoyne river was always a favourite, but you never quite knew where the channels would be following a flood.

MacTavish, Rachel, "Water Column Ammonium Concentration and Salinity Influence Nitrogen Uptake and Growth of Spartina Alterniflora" (2014). Electronic Theses & Dissertations. Paper 1162 (link)

Rachel M. MacTavish and Risa A. Cohen. "A simple, inexpensive, and field-relevant microcosm tidal simulator for use in marsh macrophyte studies". Applications in Plant Sciences 2(11): 1400058. doi:10.3732/apps.1400058 (link)


  1. The Pavlovian response of Categories 2--4 to anything that appears on Watts' blog is interesting. (The absence of the 'Claim:' prefix = absence of meat powder.)

  2. Most WUWT commenters seem just to want to see their blather in black & white on their monitors, and have nothing constructive, corrective, useful or just plain interesting to say whatever. It's about time an "off-topic" axe was wielded there.


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