November 26, three weeks ago: In the aftermath of the storm system that blew over most of BC, we went down to White Rock beach to see what had blown in. Just logs and broken plastic, it seemed. I wrote about it here.
I collected some fresh seawater for my critters in the tank at home; only about one litre, since I'd forgotten my regular 2 litre bottle. The water was dirty, with bits of eelgrass, wood chips, sand and muck, all whipped up by the crashing waves. It didn't matter; at home, as I have done before, I filtered it well, then let it sit for a few days for the fine silt to settle out.
The next week, as usual, I replaced 2 l. of the old water in the tank with new, including the latest beach collection.
All seemed well for a day or two. Then one morning, I noticed that my female crab was having difficulties. She stood on her head, with the hind legs swaying in the water, spread out. It took her a long time to right herself, but then she seemed ok. Until the next time I checked on her, when I found her caught upside-down in some seaweed. Something was wrong. (And she was in berry after their recent mating!)
The other two crabs seemed fine. But the big anemone was writhing and contracting oddly, making himself into a series of balls, then flat, then one ball with a pin-head tip, then a wide tip balanced on a pointed base, never opening tentacles to feed. A smaller anemone had disappeared entirely; so had the eelgrass isopods. I couldn't see any limpets, nor any pairs of amphipods waiting to mate. And the snails, those indestructible nasas and mud snails, were lying about, half out of their shells.
I hurried to change as much of the water as I could for freshly-prepared artificial seawater, adjusted for just-right salinity and temperature.
The next day, the anemone was worse; only a few snails were moving. Three clams were holding their siphons well out of the sand, about an inch high. I've never seen them do that before. And the big male crab was lying paralyzed, with legs stretched out and up, towards the back. The female was upside-down more often than not. The little male had disappeared.
I did what I could; removed everything to a "hospital" container with fresh water and clean stones, twice; watched and hoped. For a while, it looked as though the male would recover, but no, he relapsed. The snails died.
When the little male (that I had raised from crab babyhood) floated belly-up, too, I gave up. I drained off the water and replaced it with alcohol. They died quickly.
|The baby, with anemone, in happier days.|
What had happened? I have gone over and over each step of those days; the only source of whatever killed my tank would have been the water from the White Rock beach, where I have always collected water. And the only difference there would have been the after-effects of the storm. Was it contaminated rainwater from the city on the hill above the beach? Or something brought in by the wind and waves? I don't know.
(My previous die-off, not as complete, was caused by local pollution, blown in from next door. There was no sign of that this time, and the symptoms and species attacked were different.)
We have seen, on occasion, areas of the beaches we visit where large numbers of dead animals lie half-buried in the sand. (May, 2008, baby sand dollars, for example.) There are spots where dying clams lie thick on stinking mud; patches where we find no live animals at all, no matter how many rocks I flip, or how much sand I filter through. Sure, the areas recover, often, at least in part. Or become hosts to new forms of life, like the invasive mud snails that now cover much of the Boundary Bay beach on the Tsawwassen side. Sometimes they don't; years ago, Mom used to tell me of a beach on Vancouver Island where she could not find anything alive. It seemed impossible, back then; now not so much.
I have emptied and cleaned the tank and all the equipment, and hidden them away. I moved the furniture around so that the gap where they were doesn't show. I dumped everything previously alive in the garbage; I would normally bury it in the garden, as fertilizer, but I can't take the risk of poisoning the many animals that live in my soil. The sand will be spread, well washed first, in the most gravelly, polluted area of the vacant lot.
In the spring, I'll probably have the courage to start again. For now, I'm grieving.
I originally started bringing home beach invertebrates to learn something from them. More than just how to identify them, I wanted to know how they lived, how they interacted with other animals. I was even privileged to learn something about how they think, to see them show a reciprocal curiosity, watching me through the glass, responding to what I was doing. What kills them, how they suffer and die (that anemone's tortured contortions still break my heart!) is also something I have unhappily begun to learn.
It has made me very aware of what I buy, what I use and discard; it all enters the environment; it has the potential to do much damage. We can't turn back the clock; we've fouled our nest already, but at least I can keep from adding more poison to it.