South Atlantic
Environmental Research
Institute

An Excess of Extractions

Rhian Taylor

After a busy few months at the end of my second field season in the Falklands, I am back at Aberdeen and the pace continues to be busy! I have been to collect my samples from the BAS office in Cambridge, that were transported to the UK via the RSS Sir David Attenborough , and got them all the way to Aberdeen on the train.  

I am now currently spending a lot of time in the laboratory extracting DNA from the samples I brought back and amplifying the amount of DNA in a PCR (Polymerase Chain Reaction). This has had some trial and error, as I have a wide range of different species. So far, I have had more success with my fish larvae extractions and have worked out a protocol that is now mostly successful. This means I have been able to scale up my DNA extractions and I have been extracting between 120-150 samples every 3 weeks. For the most part, I have not found taxonomic keys to describe the larval morphology of the fish larvae species present in Falklands water (this is partly because we don’t know for sure which species are using this environment during their larval development), so DNA barcoding is the primary means of identification for these in my PhD. Most of these have been for fish larvae from different seasons so I can identify and compare which species are using the coastal environment as a nursery at different times of the year.

As well as the fish larvae, I have also been working through the different crustacean larvae in my samples. Unlike the fish larvae, there are some morphological descriptions for the decapod crustaceans (which include crabs, lobster krill and prawns), so I have already identified some of the species that I have in my samples. For some of these species, only a single larval stage has been identified, so for the crustaceans, I am using barcoding either to identify (or confirm) the different larval stages of the same species, or to be able to add the DNA barcode to the online genetic database to improve the representation of Falkland Islands species there. Some of the crustaceans have almost identical larval morphology, so the barcoding will be very useful to confirm exactly which species look the same, and then I have been looking into new techniques I could use to calculate the proportion of each species present in the different samples.

Life stages of a hermit crab

Some of the DNA results I get back are still new surprises! Recently, I sent off a few DNA samples that I had thought belonged to the larval stages of intertidal and subtidal gastropods (due to the presence of a shell), but it turns out they are pteropods! These are also known as ‘sea butterflies’ – like gastropods, they are part of the mollusc family, but pteropods spend the entirety of their life cycle in the zooplankton. This does mean I need to go back through my samples more closely to try and find more of the shelled-species and barcode these. Currently, I don’t know for sure if all of the ones I’ve counted are pteropods, or if I’ve got a combination of both snails and pteropods.

In the next few months, I’m going to be continuing with the same routine. I have a list of the different morphospecies that I identified in the Falklands, and I’m gradually managing to tick them off as species I have successfully barcoded. Hopefully the rate at which I can tick these off speeds up soon - but I definitely have a lot to keep me busy at the moment!

Electropherogrm showing base pairs of DNA Barcode

This project is hosted by the University of Aberdeen and SAERI. Collaborators and sponsors include Fortuna LTD, Darwin Plus, Shallow Marine Surveys Group, Falkland Island Fisheries and the Environmental Studies Budget (Falkland Islands Government). Rhian’s PhD supervisors include Dr Jesse van der Grient and Dr Paul Brickle at SAERI and Professor Stuart Piertney and Dr Alex Douglas at the University of Aberdeen.

FALKLAND ISLANDS OFFICE:
PO Box 609, Stanley Cottage North
Ross Road, Falkland Islands
Stanley, FIQQ 1ZZ
Falkland Islands: +500 27374
UK Office: +44 (0)203 745 1731
© Copyright 2022 - SAERI
envelopephone-handsetmap-marker linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram