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Hasta la vista, El Niño!

The strongest El Niño event on record has now been declared officially ended. For the past year and a half or so El Niño and a separate oceanographic phenomenon known as 'The Blob' have been battling it out for supremacy over weather and productivity in the northeastern Pacific, particularly in the California Current Ecosystem. It seems that The Blob, an area of unusually warm water stretching across the north Pacific from Japan to North America, had been in effect since 2014, and the arrival of El Niño combined with it to further depress productivity along the west coast of North America.

I've been recording temperatures in my seawater table at the marine lab for many years now. It has been only in the last year or so that I've made a concerted effort to record the temperature every day, but in general I have temperature data for at least several days a month going back to 1994. This morning I thought it would be interesting to compare 2016 temperatures with last year's elevated El Niño temperatures. These are the data from 1 January through 26 July of both years:

Temperature in my seawater table at Long Marine Lab. 26 July 2016 © Allison J. Gong
Temperature in my seawater table at Long Marine Lab.
26 July 2016
© Allison J. Gong

The data are discontinuous in both years, but there are a few things to note. In the winter and spring there isn't much difference in temperature between 2015 and 2016. Things change in April, when the 2016 temperatures are higher than in 2015. The El Niño was still in effect this past spring, which is reflected in the water temperatures. In May things get interesting. Starting in about mid-May 2015, the water temperature rose up to 15°C and remained at least that high for the next few months, with a handful of recordings as high as 18-19°C (data not shown). So far in 2016, the temperature has not exceeded 16°C in my table, and since mid-May has been averaging in the 14-15°C range.

A difference of 2°C may not seem like a big deal at all. One of my goals this summer was to collect plankton samples periodically and see if I could detect any biological signs that El Niño was abating. Of course, those plans got waylaid by the accident; I haven't looked at a plankton sample since 27 April 2016. On the other hand I did manage to get out into the intertidal a few times after the accident, and noticed some differences from last year:

  1. Okenia rosacea, the pink slugs that were everywhere in the intertidal last year, were much less abundant and a lot smaller this year. Last year it seemed that everywhere I looked I saw what looked like blobs of pink bubble gum spattered all over the rocks, along with their egg masses. This year I've seen Okenia but they aren't nearly as conspicuous as they were last year.
  2. Same goes for the large sea hares, Aplysia californica. Last year they were big weighty animals, common enough to make it hard not to step on them, and their spaghetti-like egg masses were everywhere. Seriously, many of the sea hares last year were two or three times the volume of my cupped hands. I did see several of them at Franklin Point last week, but they were much smaller.
  3. I don't have any quantitative measures or species-specific observations, but the algae seem more lush this year. And judging by what has been washing up on the beaches, the diversity is up, too.

We're in that time of the year when the good low tides disappear for a couple of months, so there won't be any more tidepooling excursions for me until October. Given the non-functioning condition of my brain, it's probably just as well. I hope that some time this fall I can do some real science again, as it would be very interesting to see first-hand how the biota responds to the end of El Niño. Brain health must come first, though. For the time being I will have to content myself with eavesdropping on science and doing the little bits that I can.

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