End of pre-border hull surveys and a trip to South Georgia on the hunt for marine non-native species

Dr Siobhan Vye

We are now two thirds of the way through the South Georgia and South Sandwich Islands marine non-native species project. The focus of the project to date has been on collecting data; from hull surveys of vessels operating in the seas around SGSSI, to collecting completed questionnaires across the fleet. The highlight of the past few months has been a visit to King Edward Point base in South Georgia to gain a better understanding of the operations and potential marine biosecurity risks and complete a search for high priority marine non-native species. As Winter draws in here in Stanley, the focus of the project has shifted to analysis and interpretation, using the data collected to better understand risk and potential management options that could be considered for the future.
Trip to South Georgia

In April, I was able to secure funding through the Shackleton Scholarship Fund and support from the Government of South Georgia and the South Sandwich Islands to travel to South Georgia for a ~2.5 week stay at King Edward Point research base. The purpose of the trip was threefold:
1) to conduct a survey for high priority marine non-native species; 
2) to trial and develop simple monitoring techniques for these species at King Edward Point (KEP) and 
3) to get a better understanding of how vessels operate nearshore to inform analysis of risks.

I set sail on the Pharos SG, South Georgia’s fisheries protection vessel, towards the end of April, joined by colleagues from the British Antarctic Survey who were visiting the base to work with BAS staff deployed there for a couple of weeks. After 5 days at sea, we entered Cumberland Bay in the early hours of the morning in overcast, wet and foggy conditions. After a friendly welcome by the BAS base team, we settled into KEP life. The weather was fine on the Sunday, so we took advantage to get out in the mountains surrounding the base and get our first birds eye view of KEP, Grytviken, and Cumberland Bay.
On Monday, it was time to focus on field work and start the survey. As one of the purposes of the trip was to test out different methods to look at easy ways to monitor for marine non-native species in the unique context of KEP, I had a range of different kit to use to collect data. Over the next two weeks, I trialled and developed survey techniques and tried to cover as many of the artificial substrates as I could in the time.
Siobhan deploying the ROV from the dolphin at KEP
Transporting the ROV via wheelbarrow at Grytviken
From a previous project, there is a list of high priority marine non-natives I was focused on. These are ones that are more likely to be introduced through pathways such as hull fouling and ballast water, are known to successfully establish upon introduction elsewhere in the world, and have a range of impacts on the native marine ecosystem. Many of the species are benthic and/or sessile including mussels and sea squirts, which mean they like to grow attached to a hard surface. This made the artificial substrates at KEP the target for the surveys, especially as structures like wharfs and jetties are commonly hotspots of marine non-native species and are often the first areas in a new location that marine non-native species establish.

Over the two weeks I used three main techniques to look for marine non-natives, an ROV, an extendable camera and environmental DNA sampling. The remote context of South Georgia means that entering the water through diving or snorkelling has substantial health, safety and logistical constraints. For regular monitoring, the resources that would be needed to support dive and/or snorkel techniques are considerable. Therefore, the techniques I was utilising for the trip were all shore or boat based. Many ports and harbours use rapid assessment techniques, accessing all available substrates from the surface, by leaning over the edge of pontoons to look at what is growing near the surface and lifting ropes and lines out of the water to inspect. This technique can be extended by using a camera on a pole to reach more areas under the surface, and is one method I tested on the trip.

I also used a small ROV or remote operated vehicle to survey the structures. ROV’s are drones that operate underwater. Attached to the surface by a tether that supplies power and information, the ROV can reach much greater depths and is high manoeuvrable. The ROV enabled me to capture video footage from the full depth of the structures to review for marine non-native species. Assisted by Tom 
from the KEP base team, we deployed the ROV off the wharf, dolphin and jetty at KEP and Grytviken and even managed to capture footage of the hulls of some of the wrecks at Grytviken as well.
The final method I tested on the trip was water sampling for environmental DNA. Like humans constantly shed skin and hair, marine organisms also shed cells into the water. These cells contain DNA and once collected and analysed, allow us to identify which species they have come from. This new and exciting method for investigating biodiversity also holds a lot of potential for detecting non-native species as eDNA can be quicker to sample than resource intensive visual survey techniques. However, there are still plenty of unknowns with environmental DNA, such as how long it lasts in seawater before degrading, how far eDNA can travel, and how much eDNA different species shed. Research is still piecing together what these unknowns mean for the interpretation of eDNA sampling, such as the confidence that can be placed of an eDNA detection 
meaning that the species is present at the sampling site, or the absence of eDNA meaning a species is likely not to be present. Nonetheless, for the remote context of South Georgia, eDNA could potentially be a new and exciting tool for the early detection of marine non-native species.

The fieldwork was enjoyable and challenging. Over the course of the 2.5 week trip, winter set in and our final few days were marked by substantial snow, ice forming on the water in the cove, and daytime temperatures rarely above -5°C. At points, it required a bit of ice smashing to deploy the ROV and careful navigation to return to the surface for retrieval through a hole in the ice! Alongside fieldwork, the trip was highly enjoyable for th emmersion in day to day 
Giving an evening talk to the base team in the research station bar
Waving goodbye to to KEP and the base team
research station life. From sitting down with the base team for evening meals and a Eurovision watching party, to weekend mountain walks and a bowling night in Grytviken with the crew of the Pharos SG, the base team welcomed us to their home away from home. We waved goodbye to the station team in mid-May and set out in stormy weather for Stanley, having to pause the voyage to shelter from winds that reached 78 knots! Final results and recommendations from the trip are expected over the coming couple of months.
What is next for the project?
The project is now focused on analysis and reporting – taking all the data collected over the past 7 months and pulling it together to draw useful conclusions and recommendations for marine biosecurity for South Georgia and the South Sandwich Islands. Our thanks go to all stakeholders who have facilitated data collection, the KEP research station team, the Government of South Georgia and the South Sandwich Islands, and the Shackleton Scholarship Fund for their support with the work over the past few months.
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