Thursday, 23 June 2022

Starfish Report 2022

Maimed P. ochraceus with a
replacement ray coming.
So here we are again, back at the usual beach, counting starfish. (On a -5 tide! The Woodstock of marine biology nerds.)

News on the viral front remains guardedly optimistic. In a nutshell, several species present that are susceptible to starfish wasting disease continue to indicate resilience to one extent or another, though the depredation of the virus is still evident.

The bad news is that there is still no Pycnopodia and no Pisaster brevispinus. Researchers suggest the first may now be extinct here, though I hold out hope for deep-water populations of both that may eventually repopulate the shallows.

Meanwhile, that other Pisaster – the iconic North Pacific ochraceus – continues to display real backbone. In addition to a few full-grown specimens that are looking very intact if a bit pale, I also found some badly maimed ones that nevertheless showed no signs of current infection, and were even regrowing eaten limbs. This acquired immunity – if that's what I'm seeing – bodes well for a return to former numbers.

Evasterias troschelli also maintains a pronounced presence, which is more good news, given that this was another species
Young Evasterias troschelli.

virtually wiped out on North Coast beaches the instant the virus appeared. Many juveniles dot the beach now – more, I believe, than last year – though so far no fully grown ones. That last point remains a bit troubling; these animals may still be falling to infection before reaching adulthood. But a few mid-sized ones, scattered among the bright, colourful youngsters, give hope that this species too will eventually surmount the plague entirely.

In any case, there was little evidence of active infections anywhere on the beach, which all by itself is huge.

For the rest, leather stars (Dermasterias imbricata) still mostly own the low intertidal zone. Formerly sparse in southern Puget Sound owing to heavy predation by Pycnopodia, the disappearance of that rapacious marauder, combined with Dermasterias' near-immunity to the wasting disease, has handed it a golden ticket. (Bad news for the anemones though, since this star goes positively Pyncopodia on their figurative backsides.)

Also of note were the continued presence of a few neon Henricia leviuscula, another genus that's largely, though not entirely, impervious to the virus.

So there you go. No miracles, but a heartening show of evolutionary vigour from those species that survived the first wave.

Two juvenile Dermasterias.

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