The fin of a Bat Ray (Myliobatis californica) at sunset.
Bat Rays are powerful swimmers and since this was a calm night, sometimes their strokes created wide-ranging ripples across the surface of the harbor:
Although I'm used to seeing phalaropes picking insects (or other invertebrates) out of the water or off the surface, this morning many of the phalaropes were snatching flies out of the air! In the photo above, can you see the fly above the phalarope's bill?
Here's another phalarope leaping into the air to catch a fly, ballet-style:
This morning I was watching some Barn Swallows (Hirundo rustica) feeding on insects along a rocky intertidal surge channel when I noticed that a few of them were landing on the rocks along the sides of the channel. There was a mix of adults and juveniles. Here are two different juveniles.
Arriving at the coast in the early afternoon, Eric spotted a number of dragonflies cruising back and forth along a dune ridge. I went back to check on which species it was. They were primarily Common Green Darners (Anax junius), but there were a few Spot-winged Gliders (Pantala hymenaea) and Black Saddlebags (Tramea lacerata), too.
Although this is the time of year when we can see dragonflies moving along the coast, I'm not sure what triggered this particular movement. It didn't seem that warm and I can see in the air temperature records that the maximum temperature this afternoon was ~66°F (19°C). Winds were relatively light today, out of the southwest this morning, becoming northwest later in the day. Maybe the dragonflies were triggered by conditions elsewhere that aren't as apparent in Bodega Bay.
Earlier this month, I was looking at a sandpiper and initially wondering if it might be a Baird's Sandpiper (Calidris bairdii). It turned out to be a Sanderling, but today I found a definitive Baird's, so here you go!
Baird's Sandpiper — in the wrack line (above), walking along the sand, and probing for amphipods. Photographed on 21 August 2021.
A wonderful close-up of Aplysiopsis enteromorphae, a sap-sucking sea slug found locally in Bodega Bay last week. I wrote about this species several years ago, so to learn more about them you can check out the post called "One cell at a time" from 23 September 2017.
P.S. The rhinophores are sense organs — in this species they are rolled into a tube (they're the prominent tentacle-like structures extending out in front of the eyes), and in this individual they are a striking reddish color.
P.P.S. Thanks to Jacquie for spotting this well-camouflaged sea slug!
One morning last week when we were headed out to do field work, we noticed an odd smell in the area and later we found the source — some small patches of California Mussels (Mytilus californianus) that had died recently.
Although it's been warm inland, I didn't recall noticeably high air temperatures at the coast, so at first I was a bit puzzled. But then I thought about how calm the ocean has been (hardly any large swell) and that this site is quite high on the rocks. It's likely that the mussels growing here are used to getting splashed by waves, and if they didn't experience any wave action during a warm day, it could be a problem for them.
So we did a little sleuthing regarding the conditions that might have caused this mussel die-off. Questions we wondered about included:
- Were there any higher air temperatures in Bodega Bay recently? We looked back at some temperature records and noted a couple of days in early August when the air temperatures reached ~67°F (~19°C). That was the warmest we found, so the air didn't get that hot.
- But we know that mussels and the rocks they grow on reach warmer temperatures than the air. So how hot was the rock at the time? Luckily, Eric had some data loggers on the rocks near mussels and so he looked back and found that rock temperatures reached ~98-100°F (~37-38°C) on those warmer afternoons. That's warm enough to impact mussels, and if exposed long enough, it might kill them, but it would depend on other conditions at the time. So...
- What was the timing and height of the tides on those days? Interestingly, this was during a neap tide series. Compared to tide heights during a spring tide series (around full moons and new moons) the high tide heights during neap tides are relatively low. For example, the morning high tide on August 1st was only 3.7 feet (higher high tides in our area are often over 6 feet). And the low tide on August 1st was 2.7 feet at ~12 p.m. This combination of a very low high tide in the morning followed by a low tide in the middle of the day is potentially dangerous for a marine organism living in the high intertidal zone, especially if the wave conditions are extremely calm and the air is relatively warm. It basically means that mussels growing at that site (at about 5 feet elevation) were exposed to warm air/rock temperatures and no wave splash for the entire day — especially from late morning through late afternoon (the hottest part of the day). On 1-3 August 2021, these mussels might have reached temperatures >86°F (>30°C) for 4.5-6 hours each day and they might not have experienced any wave splash for that entire time. [I think it's even possible they didn't get splashed during the night-time high tide (which on August 1st was 5.6 feet at 7 p.m.)]
So questions remain about this die-off, but rather than being caused by extreme warm air temperatures alone, in this case I'm guessing it was a convergence of factors, including (1) these mussels lived very high in the intertidal zone at a very splashy site; (2) there was a low high tide in the morning (the mussels weren't submerged during high tide); (3) there was a low tide in the middle of the day (the mussels were exposed to warm air for many daylight hours); (4) there were warm air temperatures (this might not have happened if air temperatures had been cooler); and (5) this occurred during very calm sea conditions (the mussels weren't cooled down by wave splash).
This mussel die-off was restricted to a very high intertidal splash zone site. Most of the mussels in the rest of the intertidal zone were fine. But seeing this event was insightful for considering combinations of factors that could be lethal for mussels.
One more photo for the record:
Eric took this beautiful photo of a Veiled Chiton (Placiphorella velata) found with his class today (11 August 2021):
I love the pink and white striping...the color matches the crustose coralline algae growing on the rock. And note that the chiton's plates are festooned with small tubeworms (white or gray calcareous tubes with bright orange tentacles).
For more information about this carnivorous (!) chiton, check out this earlier post from 21 August 2012.
P.S. Thanks for sharing, Eric and summer students!
I'm running out of time tonight, but here's a nice photo that Eric took tonight — a microscope view.
For a hint about what these are, check out this post from 25 February 2020.
Looks like this could be Pink Honeysuckle (Lonicera hispidula). What do you think? Photographed along the Point Reyes shoreline on 8 August 2021.
California Ground Squirrel (Otospermophilus beecheyi) on the beach in Pacific Grove in late July.
I haven't been able to take many photos recently, but here's a recent flyby shot — Osprey (Pandion haliaetus) with a nice fish!
Last month when we were doing field work near Carmel, out of the corner of my eye I noticed this scene where a Striped Dogwhelk (Nucella ostrina) appeared to be eating a Black Turban Snail (Tegula funebralis).
Dogwhelks are predators that drill holes in the shells of their prey to access the soft inner tissues. It's common to see Striped Dogwhelks eating barnacles and mussels, but we don't often see them eating other snails.
To be sure, we pried the dogwhelk away from the turban snail and found the evidence (below). The blue arrow is pointing to a drill hole along the edge of the snail:
At the end of the day today (2 August 2021), I was helping Eric prepare for class tomorrow when I spotted a small group of shorebirds including a sandpiper that I thought could be a Baird's Sandpiper (Calidris bairdii). I didn't have binoculars or a camera at the time, but afterwards I went back for a quick photo. Here are the first two images:
