... sleep deprivation and a wet head.
Night zooplankton sampling one of twenty seven. Actually an extension of day two because of some really bad weather coming in.
After dark we take a 5 litre integrated sample from each tank. We do this at night to make sure of an equal distribution of zooplankton within the mesocosms - during the day they will hide in the macrophytes from their fish predators. The water is then filtered through a 20µm mesh and then the zooplankton caught are washed into a bottle before being preserved with ethanol. Identification and counts (the most fun part) happens at a later date.
How wrong I could be. At the height of summer sampling start times were as late as 11.30 p.m, and end times as late as 2.35 a.m because of course now that it is summer its light for longer and more of the tanks (all of them it seems) have high algal biomass so trying to filter five litres of water per tank through a 20μm gauze can take some time. I have never been so happy for the days to get shorter again.
Sometimes when algal biomass is really high its just not possible to get the sample through a 20μm gauze so we filter through a 50μm instead. This still captures most of the zooplankton but the mesh size is too big for some of the smallest rotifers. During the winter all of the tanks would go through a 20μm gauze without any problems, below shows you the situation at the end of August - mainly 50μm filters. It demonstrates nicely how different the biomass is between the winter and summer months.
This last ever night zooplankton sampling finished at 10:25pm, all went well, a bit windy but no rain, until I was packing up the buckets and out of nowhere one big torrential downpour hit me. From bone dry to soaked in a matter of seconds. Boy am I glad that its all over!
All in the name of science. Plankton will make me do the strangest things.
I have managed to turn my rather unhealthy obsession with plankton in to my day job. Things don't get much better than this! This blog documents my PhD research and the plankton delights I encounter along the way.