This year, we also research what role DNA (the genetic code containing the information of life, of which a copy is stored in every cell of all organisms) can play during the IBTS. DNA-based techniques can be used for a variety of applications; from species identification to biodiversity assessments and even physiological processes in fish could be determined from the DNA. Two of these applications are being tested on board the Tridens: the identification of species by means of DNA and the biodiversity assessment based on the DNA floating around in the seawater.
Environmental (e)DNA
Imagine; you take a liter of seawater, and based of this one liter you can read which fish species are swimming around on the location of interest. It sounds a like an episode of a futuristic series, but more and more data show that measuring the "environmental" DNA (eDNA) is a good representation of the biodiversity. It would be really cool to measure occurrences and quantities without having to catch a single fish! At the moment, this lays still in the future, but with this study we are already testing what role eDNA could play during IBTS.
We take water samples with the CTD rosette at 5 meters from the bottom, where the GOV net also passes and a water sample in the water column. Water samples are also taken from the water that comes directly from the net. This water is very fishy; full of scales, mucus and blood. That water is then filtered, and the concentrate of cells and loose floating DNA from fish that remains on the filter will be analyzed in the lab.
Identification of fish with DNA on the boat
We also sampled a number of fish to identify them based on their DNA. But also to see whether it is possible to do the DNA analysis on the boat. Is it possible to sequence (the word for DNA "measure") on board? Yes you can! While typing this blog, there is a small device that looks more like a tablet then laboratory equipment to measure the DNA strands. Every 5 minutes it gives a report on the quality and quantity of the DNA. We sampled species such as common dragonet, spotted dragonet, argentine, and poor cod for analysis. In principle you only need a very small piece of tail fin for this. Through various chemical processes, the DNA is separated and cleaned from the tissue and cells of the fish tail. A few short extra chemical processing steps, and then the DNA is completely ready to be measured.
Fortunately, we were anchored this weekend to shelter from a storm in our sample area. This made it easy to conduct the experiment. Next Challenge: Sequencing in a Storm! ;)
