Warming up for Climate Resilience

Dr Jesse Van der Grient

The DarwinPlus project focusing on climate resilience in the Falkland Islands marine ecosystem and fisheries has hit the ground running with lots of different things happening. We trialed our methods for

The Darwin Plus project focusing on climate resilience in the Falkland Islands marine ecosystem and fisheries has hit the ground running with lots of different things happening. We trialed our methods for observing zooplankton in Berkeley Sound under the supervision of Peale’s dolphins, sea lions and penguins, and who could ask for better supervisors? We have received our new bongo net, which will allow us to sample zooplankton at two different size classes. It was great using it for our first spring zooplankton samples , and we will continue to use them to capture the rate of change of the zooplankton community and investigate the diversity, abundance, and biomass of various species in the nearshore marine environment. This data will inform our future ecosystem model regarding the seasonal change in zooplankton as well as provide data for a new PhD student who will investigate inshore-offshore connections, life history and genetics in these species.

Right: Dr Simon Morley at work at Fortuna, looking after amphipods.

Further, we have made a lot of progress on the physiology part of the project. Part of understanding how climate change may affect the ecosystem is understanding how animals respond to warming. This can be studied in individual species via the use of controlled experiments where we can determine how well animals do at ambient temperatures and under different warming scenarios. This work would not have been possible without the help of two project partners: British Antarctic Survey (BAS) in the UK and Fortuna via FIFCA here on the Falkland Islands. Dr Simon Morley from BAS has been over to our beautiful Islands to help set up and provide training for the physiological experiments.Without the aquacultural facilities of Fortuna, we would not have been able to set up and conduct these experiments so we are immensely grateful to Fortuna for providing the space and materials for our investigations.

There are several key species in the marine environment of the Falkland Islands, including squid (e.g., Doryteuthis gahi), rock cod (especially Patagonotothen ramsayi), lobster krill (Munida) and an amphipod (Themisto gaudichaudii) that are all important in the food web and the first two are also important commercially. Further, inshore kelp forests play an important role as nurseries for many species, such as for squid and rock cod. We will investigate the animals (as well as kelp later in the year) to determine whether they are “winners” or “losers” under climatic warming conditions. We can determine this by estimating their respiration rate. Many of our marine fauna are ectotherms, so they cannot generate their own body heat (humans and other mammals can; we are endotherms). Ectotherm body temperatures are thus equal to the environmental temperature. Respiration rate is a measure how organisms are doing, and specifically how quickly there are using energy. Quicker respiration rates are an indication that more energy is used up, and thus also that more energy (food) intake is required. However, all animals have an upper thermal limit above which they cannot survive. The respiration rate can indicate things are not going well as there will be a quick drop in the respiration rate. By understanding this relationship between temperature and respiration rate, we can understand how organisms may respond to climate change. This temperature-respiration relationship varies between species, geographical locations, and life stages. Our physiological experiments will estimate respiration rates of various organisms in response to warming, and these relationships we will obtain will be used in our future ecosystem model to help understand how organismal responses to climate change may affect directly and indirectly (via changes in prey-predator food-web connections) the marine ecosystem. While we are still far away from that model, it is exciting to start obtaining the relationships that will inform the model via the experiments we are currently working on.

There are three species we are working on right now, two amphipod species and the Patagonian squid (D. gahi) eggs. Clearly, these animals differ in size, and we use different methods to measure the respiration rates of the animals. We have a special system for the small animals where we can continuously measure their respiration rate, and program the system such that we can measure the rate of oxygen usage for a set period of time, and then provide the animals with oxygenated water.

The animals that are being tested right now are (image above) amphipods (the nereid worm was released back into the wild), and (image above left) squid eggs

We do  not have such a system for the squid and instead we have jars which we monitor closely and release the squid eggs from the jar once the oxygen concentration has dropped to 20% in the water. The squid eggs are an interesting species to study: for one, they have two spawning seasons, and these eggs are from the autumn spawning stock. We will repeat the experiment with the spring spawning stock.

Further, the eggs are developing, and we are starting to see the first hatchlings in the tank. Developing animals change in their respiration rate (lots of energy is required to grow), so we have several egg clusters in a control tank which we measure too, so we can understand the difference the increase in temperature makes regarding the change in respiration rate.

None of the work described above would have been possible without the tremendous help of all our partners , and I am grateful for the opportunities they provide.

Posted on First published

Filed as CategoriesUncategorised

Next news story:

Previous news story: