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Today is Monday.

Last Friday morning I was at the marine lab doing my usual feeding and cleaning stuff, and everything was fine. I was back at the lab Friday afternoon to return some animals that we had borrowed for one of the classes I'm teaching, and as soon as I got out of the car I knew something was wrong. I could smell it. Plankton bloom.

When I opened the door to one of the wet labs, it felt like walking into a wall of stench. It is a peculiar smell of excessive fecundity, which we occasionally see at the lab this time of year, due to a rapid population increase, or "bloom," of one or a few phytoplankton species. I'm not sure if the smell is actually bad or if it just seems bad because of all the negative things I associate with it. Negative things such as:  Sludge accumulating and decomposing on any horizontal surface in a table, including the surfaces of animals; said animals being fouled and dying because their respiratory surfaces are gunked up; seeing water straight from the tap coming in brown.

But whenever we get a nasty bloom like this, I am always curious about which critter it actually is. Back in the summer of 2010 there was a phytoplankton bloom in Santa Cruz that was at least partially caused by a dinoflagellate in the genus Alexandrium, some of which are known to produce toxins that work their way up the food chain and cause paralytic shellfish poisoning in people.

I took a sample from some build-up from this current bloom and looked at cells under the microscope (fun!). I was able to identify a couple of dinoflagellates right off the bat.

This is Ceratium.  I saw a lot of cells that look like these:

Ceratium cells.
Ceratium cells.
© Kudela lab, UCSC

Various species of Ceratium are present in plankton tows most of the year and as far as I know are pretty innocuous.

I also saw lots of these cells, too. This is Prorocentrum, a dinoflagellate that is pretty easy to recognize because of the little spine at one end of the cell. I don't think these guys are toxic, either.

Prorocentrum cells. ©2013 Allison J. Gong
Prorocentrum cells.
© 2013 Allison J. Gong

Lastly, there were a lot of these cells. I wasn't able to get a very good look at them and don't know for sure who they are, but they may be a species of Cochlodinium polykrikoides. I saw single cells and chains of two cells. C. polykrikoides is not nearly as harmless as the other two algae I saw. It has been responsible for fish kills in Asia.

These cells in a short chain might be Cochlodinium polykrikoides. ©2013 Allison J. Gong
These cells in a short chain might be Cochlodinium polykrikoides.
© 2013 Allison J. Gong

On my way out of the marine lab yesterday I stopped by the overlook to see what the surf looked like. I could see that the water was discolored with a brownish tinge. Look at the water as it recedes from the rocky bench. It would normally be white, but here it is kind of a dirty gray-brown color.

The good news is that today, Monday, the bloom seems to have abated quite a bit. I cleaned all of my tables and tanks on Saturday (extremely gross) and Sunday (not nearly as gross) and this morning there wasn't very much sludge at all. And the smell was nothing like it had been on Friday afternoon. So maybe we're getting a reprieve and won't have to deal with weeks and weeks of this stuff. That would be nice. My poor animals need a break from environmental conditions that are trying to kill them.

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What better way to start a new blog than to talk about sex?

This morning at the Seymour Center I noticed a blob of what looked like nudibranch eggs on the wall of one of the tanks. Looking around for the likely culprit I saw three big nudibranchs on the tank. Ooh, cool!

One of two slugs of this species in this tank.

This is Dendronotus iris, a large nudibranch, or sea slug. This bad boy/girl had a foot (the flat white bit that you see reflected in the aquarium glass) that was about 15 cm long. The brownish branched structures on the slug's back are its cerata, which function as gills. These animals do not have the ctenidium, or gill, that is typical of marine snails. Other nudibranchs carry their gills in a single plume that surrounds the anus.

This species is distinguished from D. iris by its coloration and some details of its anatomy.

There is one other big slug in this tank. It has a paler body color and cerata that are banded with orange and tipped with white.

Nudibranchs are among the rock stars of marine invertebrates--they are flamboyantly colored, have short adult lives with lots of sex, and leave beautiful corpses when they die. After a planktonic larval life of a few weeks, adult nudibranchs spend their time eating, copulating, and laying eggs. Each slug is a simultaneous hermaphrodite, capable of functioning as both male and female, and mating involves an exchange of sperm. In some other species of nudibranch the act of love can be followed by an act of cannibalism.

Nudibranchs lay egg masses in ribbons or strings that are characteristic of the species. It turns out that Dendronotus egg masses look like Top Ramen noodles:

Egg mass of Dendronotus.

Each of those individual little white blobs is an egg capsule that contains 10-30 developing embryos. These eggs were deposited yesterday (3 June) and the embryos have been developing but are not yet at any distinct stage. With water temperature at about 13C, I think they'll develop pretty quickly.

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