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Since 2000 the first Saturday in May is Snapshot Day in Santa Cruz. This is a big event where the Coastal Watershed Council trains groups of citizen scientists to collect water quality data on the streams and rivers that drain into the Monterey Bay National Marine Sanctuary, then sets them loose with a bucket of gear, maps, and data sheets. The result is a "snapshot" of the health of the watershed. As we did last year, my students and I were among the volunteers who got to go out yesterday and play in coastal streams. This year there were 13 (+1) groups sent out to monitor ~40 sites within Santa Cruz County. For reasons I don't entirely understand four sites in San Mateo County (the county to the north along the coast) were included in this year's sampling scheme; hence the +1 designation. Since I routinely haunt the intertidal in this region I took the opportunity to become more familiar with the upstream parts of the county and volunteered to sample at these northern sites. It just so happened that I was teamed with two of my students, Eve and Belle, for yesterday's activities.

Of our four sites, two were right on the beach and two were up in the mountains. Thus our "snapshots" covered both beach and redwood forest habitats. Here are Belle and Eve at our first site, Gazos Creek where it flows onto the beach:

Beel and Eve at Gazos Creek, our first site. 7 May 2016 © Allison J. Gong
Belle and Eve at Gazos Creek, our first site.
7 May 2016
© Allison J. Gong

After heavy rains the water draining through the watershed breaks through the sand bar and the creek flows into the ocean. Yesterday the sand bar was thick and impenetrable, at least to the measly amount of rain we'd had in the past 24 hours.

Gazos Creek as it flows onto the beach. After rains it breaks through the sand bar and flows into the ocean. 7 May 2016 © Allison J. Gong
Gazos Creek as it flows onto the beach. After rains it breaks through the sand bar and flows into the ocean.
7 May 2016
© Allison J. Gong

At each site we collected two water samples, for nutrient and bacteria analyses, and the following field measurements:

  • air and water temperature
  • electrical conductivity
  • pH
  • dissolved oxygen (DO)
  • water transparency
Snapshot Day data sheet for 7 May 2016 © Allison J. Gong
Snapshot Day data sheet for our Gazos Creek (forest) site.
7 May 2016
© Allison J. Gong

Here Eve is measuring conductivity in Gazos Creek (beach site):

Eve takes a conductivity measurement at Gazos Creek (beach site). 7 May 2016 © Allison J. Gong
Eve takes a conductivity measurement at Gazos Creek (beach site).
7 May 2016
© Allison J. Gong

Most of the equipment we used to take the field measurements was simple and straightforward: pH strips and a thermometer, for example. Even the conductivity meter was easy to use. You just turn it on, let the machine zero out, and stick it in the creek facing upstream so that water flows into the space between the electrodes. Here's Belle taking a conductivity measurement at our Gazos Creek (forest) site:

Belle measures conductivity at our Gazos Creek (forest) site. 7 May 2016 © Allison J. Gong
Belle measures conductivity at our Gazos Creek (forest) site.
7 May 2016
© Allison J. Gong

The only tricky field measurement was the one for dissolved oxygen (DO). This involved collecting a water sample (easy enough), inserting an ampoule containing a reactive chemical into the sample tube, breaking off the tip of the ampoule so that water flows into the tube, and gently mixing the contents of the ampoule for two minutes. Then you compare the color of the ampoule with a set of standards in the kit to estimate the DO level in mg/L (=ppm).

Standards for measuring dissolved oxygen. 7 May 2016 © Allison J. Gong
Standards for measuring dissolved oxygen.
7 May 2016
© Allison J. Gong

Our second and third sites were up in the mountains, at Old Woman's Creek and Gazos Creek (forest). With all the rain we had over the winter the riparian foliage has exploded into green. It was all absolutely lush and glorious. How lucky we were to spend the day in such surroundings!

Gazos Creek in the Santa Cruz Mountains. 7 May 2016 © Allison J. Gong
Gazos Creek in the Santa Cruz Mountains.
7 May 2016
© Allison J. Gong
Gazos Creek in the Santa Cruz Mountains. 7 May 2016 © Allison J. Gong
Gazos Creek in the Santa Cruz Mountains.
7 May 2016
© Allison J. Gong

And there were a great many banana slugs! All of them were solid yellow, with no brown spots. At one point there were so many slugs that we had to be extremely careful not to step on them.

Banana slug (Ariolimax sp.) in the Santa Cruz Mountains. 7 May 2016 © Allison J. Gong
Banana slug (Ariolimax sp.) in the Santa Cruz Mountains.
7 May 2016
© Allison J. Gong
Banana slug (Ariolimax sp.) in the Santa Cruz Mountains. 7 May 2016 © Allison J. Gong
Banana slug (Ariolimax sp.) in the Santa Cruz Mountains.
7 May 2016
© Allison J. Gong

Our fourth and final site was Whitehouse Creek, which flows into the Pacific Ocean to the south of Franklin Point. We had about a 10-minute hike to the creek from the road. By that point it had been raining for quite a while. Although we were protected from the rain by the trees when we were up in the forest, when we walked out to the field to the beach we were lucky it had eased to a light sprinkle.

Whitehouse Creek where it flows into the Pacific Ocean. 7 May 2016 © Allison J. Gong
Whitehouse Creek where it flows into the Pacific Ocean.
7 May 2016
© Allison J. Gong

After we finished our sampling we all agreed that we had to have gotten the most picturesque sites. None of the other teams got to visit both forest and beach for their sampling! We didn't drop off our samples and equipment until 14:00, a couple of hours later than the other groups, but who would complain about having getting to spend the day tromping through the forest AND the beach?

Our feet! 7 May 2016 © Allison J. Gong
Our feet!
7 May 2016
© Allison J. Gong

BEWARE: This is a mini-rant. Continue at your own risk.

Several times over the past year or so I've heard the term "king tide" being tossed about in the general media. I remember looking up the term when I first heard it, back in December 2014, and came across the following definition, which I cribbed from the EPA's website: The king tide is the highest predicted high tide of the year at a coastal location. Okay, I thought then, every year there is going to be one highest high tide and why not call it a "king tide"? A king, after all, is the biggest of the cheeses, the headiest of the honchos, the top of the heap. I could live with that, although I generally steer clear of hokey terms and wouldn't dream of using "king tide" in my classroom.

In 2015, however, it seemed that we heard about "king tides" about half a dozen times. WTF is up with that? Obviously, the highest tide of the year can't occur more than once in a year, right? So why did I read reports of "king tides" in January, around Thanksgiving, and at Christmas last year? Part of the problem is that the meaning of the term itself has morphed into something else. Instead of reserving "king tide" for only the highest tide of the year, writers are now using it to refer to any old spring tide. I detest this trend the same way I detest grade inflation--it gives an ordinary natural occurrence more importance than it deserves and doesn't make it clear what's going on.

Okay then, let's clarify.

First of all, what are spring tides, anyway? Well, spring tides are the extreme low and high tides that we get every two weeks or so. Spring tides and the intervening neap tides, during which both low and high tides are of intermediate height, are due to the gravitational pull of the sun and moon on Earth's water. Obviously the sun, being orders of magnitude more massive than the moon, has much more gravitational pull than the moon; however, the moon is much closer to the earth and thus our tide cycles are closely attuned to the moon's orbit around the earth.

Tides

The top of the figure above depicts what is going on during spring tides. During a new or full moon the gravitational pulls of the sun and moon are aligned, causing higher-than-average high tides (and correspondingly lower-than-average low tides). When the moon and sun are forming a right angle with respect to the earth their respective gravitational pulls cancel each other out a bit and result in intermediate high and low tides. These neap tides occur during the first- and third-quarter moon phases. Even people who don't live near the ocean have experienced the different phases of the moon, and that the lunar cycle is about 28 days long. Thus every month we can expect two cycles of alternating spring and neap tides.

The take-home message is that EVERY MONTH we have extreme high and low tides. You could even say (though I certainly wouldn't) that we have a "king tide" every month, since one of the high tides is going to be the highest of the month. Kinda takes the oomph out of the phrase, doesn't it? What's the fun of being a king of there are 11 other kings? Nobody gets to be THE king, which is kind of the whole point of being a king in the first place, isn't it?

So what are the reporters trying to convey? Digging a little deeper into pages from NOAA and other reputable sites, I think the intended message is that the effects of ordinary spring tides will be augmented by El Niño and climate change. Such effects include increased coastal erosion and flooding. When a spring high tide coincides with a big storm surge, which has happened here in Santa Cruz the past couple of days, the threat of flooding becomes quite real. The National Weather Service issued a high surf advisory for yesterday and today. The surf was indeed big when I went out to check things at the marine lab this morning.

In the context of a spring high tide combined with a big storm-driven surge, I can live with the term "king tide," although I still don't like it and won't use it myself. A tide is a tide and has specific direct causes; same with a storm surge. Mixing them together and slapping the label "king tide" on the conflation gives people an incorrect impression of what's going on and implies that somehow the tide and the surge are the same thing. They are not; they are two independent phenomena that occasionally happen at the same time, that's all. I am an educator and it's my job to impart scientific information in both academic and informal settings. But I feel that my job is made more difficult when the media get all hyped up about an impending king tide and either state or imply that it will be the highest high tide of the year, and then we read about it again a few months later, and yet again during the following spring tide series. It's both bogus and lazy.

Yesterday I heard (or, more precisely, was reminded) that the quinine molecule fluoresces. Fluorescence is what happens when a molecule absorbs electromagnetic radiation--either in the visible light range or elsewhere in the spectrum--and emits light at a different wavelength. Lots of molecules fluoresce. Chlorophyll, for example, is the green molecule that captures the light photons that power the process of photosynthesis. If you shine light at a wavelength of 425 nm (violet) at a tube of chlorophyll, it will fluoresce, or emit light at 680 nm (red).

Here's a DIY video guide to demonstrate the fluorescence of chlorophyll in the comfort of your own home:

Chlorophyll fluorescence

So back to the fizzy beverages. I sing in a choir that has a long tradition of gathering after rehearsals and drinking gin-and-tonics (G&Ts). Tonic water contains quinine, which imparts fizziness and a certain bitterness to the drink. Having re-learned about the fluorescence of quinine, I thought it would be fun to watch the tonic and gin mix under a UV light. We needed a dark place for this experiment, hence the bathroom, the most convenient room that we could completely darken.

Turns out it worked amazingly well. Tonic water is entirely clear under white light, which contains all wavelengths of the visible spectrum; it looks like any other unflavored fizzy water. But under the UV light it glows with a kind of unearthly blue hue:

The quinine in tonic water fluoresces under UV light
The quinine in tonic water fluoresces under UV light

But the real fun is in watching the tonic and gin mix in the glass. We make G&Ts this way: Put a few ice cubes in the glass, squeeze in a bit of lime, pour in two fingers' of gin, then top off with tonic water. So we did everything but pour in the tonic water, then ventured into the bathroom with the UV light, where I recorded this:

Now isn't that cool? Science is great!

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