Cued by a temperature change?

  

Eric was doing an end-of-day check on some tanks in the lab last night and noticed some sea urchins spawning!  Above, a male Purple Sea Urchin (Strongylocentrotus purpuratus) with clouds of sperm being released from the gonopores on the upper surface.  

Looking around, we eventually noticed a few female Purple Sea Urchins releasing eggs (more yellow-orange in color):

 

Our guess is that warmer ocean temperatures during the past couple of days triggered spawning.  There's been a lot of upwelling this year, with water temperatures as low as ~8.8°C (~47°F).  But winds calmed down at the end of the week and temperatures rose to ~12°C (~54°F).

There were also a couple of other echinoderms spawning.  Here's a male Red Sea Urchin (Mesocentrotus franciscanus) releasing sperm:

 

 

 

And a female Ochre Sea Star (Pisaster ochraceus) releasing eggs:

 

 

 

What's that saying, "Spring is in the water"?  ;)