Wednesday, August 8, 2012

The final push

It's my last week on Lake Tanganyika for the year, and Ben and I have One Last Big Project component to finish up before I head home: Fish excretion, or more aptly: making tiny fish toilets out of Ziploc bags.

For the few of us that remain, it’s all hands on deck, as each of us has a part to play in the endeavor. I won’t even attempt an explanation of the various components, but here’s an Extremely Brief Overview of what the others are doing:

Renalda is doing something involving length and weight relationships of Tropheus brichardi (again, the details are fuzzy…)

Lesley is studying fish metabolism, so her fish go into special PVC chambers and she monitors the oxygen demand of the fish.

Look closely! There's a little fish in there, swimming away.
Benja and I collect fish pee from 6 species of cichlids representing different trophic levels (more on that in a minute…)

We're trying to get sponsorship from Ziploc.
And Ryan collects poop.  

The life of a field ecologist is nothing if not glamorous. 
We’re currently on Day 3, and at any given moment it has potential to cross that fine line between Well-Oiled-Machine and Total Shitshow. 
We did a version of the excretion project last year, and I seem to have forgotten (until recently!) how intricate and all-absorbing and absolutely exhausting it all is (and I’m not the one staying up until the wee hours playing with “cancer juice” and the fluorometer. That’s Benja’s job. But more on that in a minute). 

The downsides (baking in the sun, sitting on hard rocks all day, and sweating bullets on shore) are mostly outweighed by the good stuff (Ryan’s homemade guacamole, not-super-stale popcorn from our friendly duka-owner, and good tunes blaring over the lab speakers). I still maintain that even a bad day on the water is better than the best day on land. But that’s just me.
Here’s the rundown of a typical excretion day:

The night before:
Benja spends a couple hours or so filtering lake water with an electric vacuum pump. That may seem like an unnecessary detail, but it is NOT, Dear Reader. Last year we did it all in the field with hand pumps, filter towers, and flasks, and by the end of the summer I had Popeye forearms. I did not wish to repeat that muscle exercise, so the mechanized version is a dream!

I label up water vials and Ziplocs for all 41 fish we'll be sampling.

Early AM:
Gather all the gear for the day and walk it down the beach. Lately we’re using George’s boat, the Maji Makubwa, since we’re down to one Zodiac and Too Many People/Too Much Gear. 

Georgie at the helm of the Maji Makubwa
10 a.m. and on:
Head to today’s site and try to find some nice (and accessible!) shoreline. It was Damn Windy this morning, and this maneuver involved a brisk (!) swim, floating gear over our heads while waves bashed us into the rocks, and manhandling aforementioned heavy gear over slippery boulders. Something about it didn’t feel very safe…

Set up shop. Measure 2L of filtered water into individually numbered Ziploc bags (this takes about an hour…)

This is my super-awesome/fabulous field hat purchased in Zanzibar. NICE, huh!
Georgie suits up and starts catching fish.

Georgie hands fish off to Benja, who aerates the water (read: shakes Ziploc violently for a few seconds) and gives the fish some alone time (enough time to pee anyway…)

Passing off a fish to Benja. Georgie brought along a friend who hung out in the boat all day during this operation. She was Bored Out Of Her Mind.
Into the filtered water he goes! On this particular day, we braved a lightening storm (!!!) to get to Site 9 and thanked our lucky stars no one was electrocuted. Seriously. It was terrifying.
After 30 minutes, it’s GO TIME, rapid fire. Benja filters pee-water for nutrients and I pipette straight-up-pee water into amber bottles for eventual ammonium analysis. 

I hand off the fish to Renalda, who gets lengths and weights for us. Ryan takes the Ziploc, holds it until all the poop settles to the bottom, and collects turds into pre-weighed vials. Mr. Fish goes into a holding tank until we can release him to the lake. 

I like to think they're happy, but there's really no way to tell. I think he's smiling?
Do this 40 more times.

START TO OVERHEAT and really need to jump in the lake and excrete with the fish :).

Avoid eye contact, avoid eye contact...
Late afternoon:
Load up gear, drop by tomorrow’s site to collect water for filtering, and start motoring home.

Heading home! Georgie always has a smile!
Unload, unpack samples, and pipette “cancer juice” (OPA, a scary, scary chemical necessary for ammonium analysis) into the samples. Wait 4 hours for the reaction to complete.

Meanwhile, Benja filters water and I label bags and vials for tomorrow.

The wee hours of the morning:
Break out the fluorometer and read the ammonium levels of all samples.

The next day:
Do it all again!

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