Monday, April 18, 2011

Silt, or the Aquarium meets Jaws

When the barge arrived, the touch tank got very scary for a few hours over the weekend.

The aquarium is in the middle of a major project to clean out our saltwater intake lines – these are two big pipes that take salt water out of the bay and into the tanks in our building.   So yesterday, the big barge, which is going to be the staging area for an upcoming phase of the pipe project, arrived in Resurrection Bay, and anchored itself directly over the intake pipes.   Unfortunately, the anchoring process apparently churned up quite a bit of muck off of the bottom of the bay - which was immediately sucked up by the pipes and fed into our tanks.   So, for a good portion of Sunday morning, the exhibit tanks looked… well, a little scary.   The water was very grey, and cloudy, and every so often, a silhouette of a fish would flicker by, or a few strands of kelp would wave in the current.    It was actually very cool seeing Woody swimming around in the sea lion exhibit – he looked like a monster-sized shadow drifting across the window.   All we needed to do was glue a shark fin onto his back, and we would have had an entirely different exhibit…   

Since there weren’t visible animals in all of our tanks, we discounted admission for the day, and people seemed happy enough with that – at least no one complained.   And the mammal husbandry staff made a point of radioing every time they were doing a feeding session, so the guests could congregate and watch.   (Woody does handstands.   No guest who sees one will depart unimpressed.)   

Some of our tanks actually looked pretty atmospheric - especially around mid-afternoon, when the water began to clear enough that the fish were visible, but the back walls of the tanks themselves were still very shadowy.   In some ways, the silty look is probably a little closer to what the water in Res Bay actually looks like – so full of glacial silt and plankton that you can’t see a whole lot else.   On good days in Aialik Bay, you could see down about eight feet.   At the aquarium, you can (usually) see all the way to the bottom of our deepest tanks, around 20 feet down.   

The Kelp Forest tank looking mysterious

The seabirds in the aviary certainly noticed that there was something going on with their water; they kept sticking their heads underwater and looking around.   And when Eden and Tasu came out into the habitat later that afternoon, they seemed even less happy than usual about getting in the water with Woody, their 2000-pound would-be boyfriend.   I don’t think they liked the idea of being in the water with him, but not being able to see where he was.   Eden jumped in eventually, and she and Woody spent a few minutes nuzzling and nipping, which seems to have become their standard way of saying hello.   (If Woody gets too rough with her, she’ll turn around and bite him on the lip; Eden may be our smallest sea lion, but she knows how to take care of herself.)

The touch tank, however, was just downright scary.   For the first few hours we were open, the water in the tank had the consistency of chocolate milk – this solid grey expanse of water, broken occasionally by gelatinous anemone tentacles, or prickly urchin spines waving above the surface.   Not a very inviting sight for the touch tank.   It was impossible to see any of the animals at the bottom of the tank – and even I did not want to stick my hand all the way to the bottom of the tank, for fear I would get too close to a pissed-off hermit crab.   (I’ve never seen any of our crabs pinch anyone, ever – but I have seen them try a couple of times.) 

By the end of the day, the debris kicked up by the barge seemed to have settled back down, and the water in most of the tanks looked noticeably clearer.   However, many of the touch tank animals looked two or three shades greyer than they normally did, from all of the silt that had settled out on their backs.   The sea cucumbers looked particularly dingy; it almost looked like I needed to go through the tank with a feather duster.

I do want to mention that having silt in our water – even in quantities large enough to cloud up a six-inch tank – is in no way harmful to the animals that actually live in the water.   Silt is naturally found in the water in Resurrection Bay, (after major rainstorms, the Bay can become very silty just from increased surface runoff), and the critters that live in the Bay deal with the silt just fine.   (Also, any bits of plankton or food particles that were sucked into the pipes will be eaten with relish by the anemones, barnacles, and other assorted filter feeders living in the building.)   The silt is really only an annoyance to the guests - and to the aquarium staff whose job it is to clean this stuff out of our tanks.  

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