Blitzin’ the intertidal, part 1

This is the second year that the California Academy of Sciences has sponsored Snapshot Cal Coast, a major effort to document and characterize the biodiversity of the California coast. To this end the Academy has organized several Bioblitzes at various sites in northern California, and solicited volunteers to lead their own Blitzes, either as individuals or with groups. A Bioblitz is a citizen science activity in which people take photographs of organisms or traces of organisms (shells, scat, tracks, etc.), then upload their observations into iNaturalist. Experts then identify the organisms in the observations, and the data are publicly available to anyone who wants to use them.

For Snapshot Cal Coast 2017 I have four Bioblitzes planned for the intertidal. Here are some of my observations made in the first two.

Day 1: Natural Bridges, Sunday 25 June 2017, low tide -1.7 ft at 06:27

My friend Brenna joined me on an early low tide at Natural Bridges. The intertidal topography at Natural Bridges consists of a series of gently sloping benches that are riddled with potholes of various sizes and depths. For the purposes of this Bioblitz I decided to confine my observations to the geological structure that I call the peninsula, which sticks out farther into the ocean than the edges of the benches.

Aerial view of intertidal benches at Natural Bridges, with the "peninsula" circled in red.
26 June 2017
© Google Maps

The peninsula is most easily accessible when the tide is at least as low as -1 ft, although large swell can make it entirely unsafe to do so at even very low tides. Fortunately the swell wasn't big enough to keep me from the peninsula yesterday, and I confined most of my observations to this location. I've found that making observations for Bioblitzes requires a different kind of attention and focus than either collecting or observing for more general purposes. In the spectrum of forest-to-trees levels of observation, Bioblitzes are all about individual trees. When left to my own devices I tend to move quite fluidly between forest-level observations (e.g., broadscale ecological patterns) and tree-level observations (e.g., what organism is that?), and confining myself to only tree-level observations was, well, confining. It's undoubtedly a good discipline, but one that I find a little stifling.

Here are some of the "trees" I saw at Natural Bridges.

Anthopleura sola
25 June 2017
© Allison J. Gong
Haliotis cracherodii, the black abalone
25 June 2017
© Allison J. Gong

I've been keeping an eye on this abalone for a couple of years now. It has gotten bigger and in the last year has become heavily encrusted with other animals and algae. Right now it is sporting lots of acorn barnacles (both large and small), at least one tube of Phragmatopoma californica, limpets, encrusting and upright coralline algae, and other red algae.

The red alga Smithora naiadum 
25 June 2017
© Allison J. Gong

Smithora naiadum is a red alga whose thallus consists of small flat blades. It grows only as an epiphyte on seagrasses, in this case the surfgrass Phyllospadix scouleri. Later in the summer many surfgrass leaves will be almost entirely covered with Smithora.

My favorite observation of the morning was this little hermit crab.

Pagurus hirsutiusculus, the so-called hairy hermit crab
25 June 2017
© Allison J. Gong

I love how this hermit is clinging to a piece of giant kelp. It lives in a shell of the olive snail Olivella biplicata, as many of its conspecifics do. These shells get to a bit over 2 cm in length, and their narrow diameter means there isn't much empty space inside. Fortunately, P. hirsutiusculus is one of the smaller hermit crabs and doesn't need much space.

An extreme low tide like yesterday's has two benefits. The most obvious is that more real estate is exposed, thus more area to explore. The second benefit of a really low tide is time. Much of the biodiversity of the intertidal is in the low-mid and low zones; the lower the tide, the longer it takes for the ocean to return and reclaim its property. I was able to spend the better part of two hours out on the peninsula, which doesn't happen every year. Lucky me!


Day 2: Franklin Point, Monday 26 June 2017, low tide -1.5 ft at 07:15

To get to the beach at Franklin Point you have to hike ~10 minutes over the dunes along a maintained trail. The views along the way are often quite spectacular, even when it's foggy. This morning it was unusually clear, and I wished I had brought along my big camera. For example, looking north towards Pigeon Point I saw this:

View towards Pigeon Point from the Franklin Point trail
26 June 2017
© Allison J. Gong

I mean, come on. How much more beautiful can a vista be?

The intertidal at Franklin Point has changed dramatically over the past year. Heavy storms over the 2016-2017 winter removed about two vertical meters of sand from the beach, exposing rocks that had been buried for years. Even today, months after the peak of the storm season, you can see bare rock that has yet to be heavily colonized by living things.

Mostly bare rock at Franklin Point
26 June 2017
© Allison J. Gong

Primary succession is the sequence of species' arrival and eventual replacement in an area that has never hosted life before. These rocks may very well have served as habitat for organisms years ago, but in my memory they had been buried in sand until the recent storms. Their exposure provides an opportunity to observe primary succession in this very dynamic habitat.

The first organisms to arrive and take hold in any newly available habitat are primary producers. Makes sense, as there is no food for heterotrophs yet. In the case of the intertidal the first visible organisms are algae. The algae at Franklin Point have been going like gangbusters all spring and into the summer. Faunal diversity, on the other hand, has been rather low. I spent quite a while looking at and photographing algae, many of which I couldn't identify in the field.

My favorite red alga, Erythrophyllum delesserioides, at Franklin Point
26 June 2017
© Allison J. Gong
A young specimen of Egregia menziesii at Franklin Point
26 June 2017
© Allison J. Gong

Some things were entirely unfamiliar to me. For example, I'd never seen coralline algae encrusting on the tips of another red alga. And yet, here it is:

Coralline algae
26 June 2017
© Allison J. Gong

As I mentioned above, animal life at Franklin Point has been rather depauperate this year. HOWEVER, I did get to let out a few whoops of triumph when I found this:

The staurozoan Haliclystus sp. at Franklin Point
26 June 2017
© Allison J. Gong

These animals, staurozoans, are incredibly difficult to photograph. Not only are they the same color as many of the algae they live with and attach to, but they like areas where the water is constantly moving back and forth. Plus, the pools and channels where I found them were cloudy with Ulva spooge. I took a lot of pictures of backscatter and blurry staurozoans.

Here's another shot:

Haliclystus sp. at Franklin Point
26 June 2017
© Allison J. Gong

Staurozoans are the strangest and by far the coolest cnidarians. Their common name 'stalked jellyfish' harkens back to when they were considered scyphozoans, close kin to moon jellies (Aurelia) and the like. They are now known to be in their own group, the Staurozoa, related to but not part of the Scyphozoa.

I don't really know why I'm so enamored of the staurozoans. Maybe it's because they are rare and poorly understood. I know them only from Franklin Point and one sighting at Carmel Point. The systematics of the staurozoans is in flux; I'm not brave enough to assign a species epithet to this critter, but a colleague who is one of the people working on this group suggests that it is H. sanjuanensis, a species that has not yet been formally described. All of the staurozoans I saw today were this brownish-red color, but in previous years I've also seen them in a brilliant bottle green. Those would probably be easier to see among all the red algae, but with my luck the green ones would all be hanging out with Ulva.

The very last part of the hike to the intertidal is a steep decline down the dune to the beach. Getting down is easy, you just sort of ski down. Getting up is much more of a challenge. Ever try to climb a sand dune? Each step gets you about a quarter of a step above the last one, so it's hard work, especially when the dune is steep. There have been times that I've hiked all the way out to the beach, only to turn around and go back because I didn't think I'd be able to climb back up the dune in my hip boots. And since I have bronchitis right now by the time I got back to the top today it felt as though I had climbed Mt. Everest.

See?

It's steeper than it looks, especially on the way up
26 June 2017
© Allison J. Gong

All told, I added about 150 observations to iNaturalist these first two Bioblitzes. I'm not really into making observations just to make observations, so for me that 150 is a good two days' production. Now I need to rest up for tomorrow's low tide.

 

One thought on “Blitzin’ the intertidal, part 1

  1. Pingback: Blitzin’ the intertidal, part 2 – Notes from a California naturalist

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