Special mission: side-experiment!

Mirian Arellano von Mirian Arellano am 6.10.2019

It’s crazy how fast time flies! I can’t believe that today is t30 ... Less than one week and the experiment in Gran Canaria will be finished. But ... not that fast! While our mesocosms are still receiving nutrient-rich deepwater and phytoplankton is growing nicely and happily, the plankton lab is planning something: an exciting side-experiment! Let me tell you about it. Throughout these five weeks, we observed that the boost of nutrients in our mesocosms has kept phytoplankton biomass and primary production at a high level, just as we expected. Surprisingly, the zooplankton (first consumers in a typical ocean food web) didn’t seem to be that happy and they weren’t present in high abundances, even though they had a huge amount of food ... but why?

This question was puzzling all of us and this is why the idea came up of doing a side-experiment to better understand why the zooplankton is not making use of the phytoplankton feast.

image5 “Copepod hunt” team; wet but happy. Thanks Captain for driving us!

For that we collected adult copepods of the genus Temora, one of the most abundant in this area. We are incubating them for several days in 5 litre containers, in with water taken directly from our big mesocosms. This way, we mimicked the conditions prevailing in our large experimental enclosures, but in way to focus specifically on the relationship between primary producers and first consumers.

Preparing side-ex Anna and Carsten preparing the incubations

At the end of the incubation, we will analyse copepod grazing (how much and which kind of phytoplankton they feed on) and their reproductive success; and we will hopefully find out which silicate treatment was providing the best food for copepods to grow on. Fingers crossed for the side-experiment!

Setting up incubations Ready, steady, start of incubations!