Conor D McGuinness Probes Scientists on Celtic Sea and AMOC Risks

I have a number of questions as well that I would really like to pose and I would like to get your input on. And I have to say that one of the things that struck me, Dr. Stemmler, from your presentation was the how the impact of the phenomena that you're researching and watching and studying may have different impacts in different parts of our coastline, the waters there often. I think you mentioned that the impacts on the east and the southeast will be more particularly pronounced and certainly may be different. In what way? Why? And then what would be the implication for that both on sea fisheries, coastal erosion and other coastal phenomena and offshore wind, which I'm sure you're aware is under development or under consideration off the southeast coast in particular at the moment? Thank you. So basically the east and southeast that I was referring to, that is especially for summer maximum temperatures, so that the east and southeast that is already warmest and driest on present day has the tendency to get even warmer and drier in the future. There is very little evidence about the wind speed again, just maybe a slight decline in the mean wind speed now if it comes to offshore energy is projected. And yeah, so to the reasons is that we would basically get a little bit more continental conditions like we have also in mainland Europe, but by far not. I mean, that would be much more. It's only a slight tendency towards the east and southeast that that would behave differently compared to the rest of Ireland. Thank you for that. So I understand the point that it refers to temperature rather than to wind. With regards to the temperature aspect, would it be accurate or fair to assume that the further south you go in terms of the waters off the south coast and the east coast, the more pronounced that impact would be? And does that have any implications for, particularly for species in that area? Maybe that's a question. The first part of that question is certainly for Mid-Ireland, but the second part is probably for ATO, the Marine Institute. But just in terms of the progression as you go south from the south coast, is it more pronounced? Yes, certainly in terms of the land impact, we know that the further south we go, the stronger, and actually the further east we go, the stronger is actually the warming tendency within Europe. So that would, of course, also have implications on the water temperatures basically between UK and Ireland and also south of Ireland. Yeah, and indeed for the impact-related aspects, I would then hand over. Thank you. Thanks, Deputy. So what we observe essentially is that, and we would understand the Celtic Sea to be essentially a constrained system. So unlike the west coast where it's open to the dynamics of the greater North Atlantic, as you move further east in the Celtic Sea, you have current conditions that set up things like fronts. There's a thing called a Celtic Sea front there that's established between the Celtic Sea and the Irish Sea. And once those fronts are established and become permanent, then the input of heat into the Celtic Sea area can have different effects. So it depends on how the heat is dissipated. So we've observed, for example, heat wave events in the Celtic Sea. And these heat wave events are typical of what we were talking about earlier, that would be stressors for fish under certain conditions. So under extreme conditions, the warmer the water, the less oxygen is held. So there's a low oxygen condition under extreme conditions of heat waves. But that's particularly pronounced and so as you move into shallower waters. So it all depends on the combination of the atmospheric conditions in terms of wind and wind events, the input of solar radiation in terms of heat, and the movement of that heat mass around in the sea. And it can impact on fish species that are locally resident in those areas. So fish species, for example, that are associated with the seabed, that don't move around a lot, will be more vulnerable in those situations to those kind of events than those that are able to move and, for example, find more optimal conditions elsewhere. Just a paper that I just recently published. While it didn't, it was mainly looking at community-related trends, so it didn't attribute those trends to temperature. But what we did find was the only ones, the only area that showed statistically significant increasing trend in Lusitanian species was in the Celtic Seas, in Isis Area 7G, which is in that southern region. Thank you. And with regard to recruitment of species and the impact, you've mentioned in response to other deputies' questions, to what extent is changing temperatures having an impact on that? And is there also something, you can imagine when we speak about fisheries issues, where we're concerned with fish that are species for catching, for fishing, and of importance to sea fisheries, but they predate on smaller organisms. Is there an impact on those smaller organisms that is having a knock-on impact on fish stocks? And either for Dr. Vaughan or Dr. Kelly or both. Well, just the recruitment question first. There hasn't been a lot of research in Irish waters with regards to, say, juvenile fish larval stages. It is a gap in the research. There has been a lot of work done on temperature influences on larval species in, say, coral reef systems, and we have seen negative impacts in those areas, which would have a knock-on effect then on the fish, the number of fish that are being recruited into a fishing stock, which will have a knock-on effect on that. And I'm sorry, what the second question was? The second question was relating to the prey that fish species are predating on, and has there been an impact on those that has a knock-on impact on the, we say, the target species for commercial sea fisheries? I'm not aware of direct relationships in the research, but there is a lot of research being done at the moment on developing these food web models where you will see that. So there has been a food web model developed for the Irish Sea, which was done under that WKIrish project that I mentioned earlier, and there are two projects at the moment working on looking at developing food web models for the Celtic Seas region, where you could potentially get into answering those types of questions. Perfect, thank you. And Dr. Kelly? Well, the only thing I can really add to that is that the issue between temperature and fish is not a direct relationship, only under extreme circumstances that I referred to earlier, that in extremely high temperatures, physiologically, the fish will become stressed, or you become low oxygen conditions. But long before that, there are second and third order interactions between increases in temperature in the water and actual stresses on the fish itself. So one of those, for example, is that if the timing of the warming, so generally in an annual cycle, the seas will warm up in spring and early summer, and that early warming, that spring warming of the seas produces biological activity at the bottom of the food chain in terms of phytoplankton and zooplankton. And if the timing of that changes, so if the seas warm up earlier, that's a very environmental, physical reaction, so those food chains will kick off with the temperature queue. But fish have been evolved over time to spawn at specific times of the year, and that's called a mismatch. So if that queue happens too early in terms of warming, you might get a peak in food productivity at one part of the food chain that's not available to the larvae of the fish that are spawned at another specific time of the year. So that's a second order impact that you can have from temperature. Temperature then can also affect current patterns around the coast, and depending on the distribution of the water masses, that actually affects the distribution of larvae. So larvae are generally designed to be entrained within an area where there's good food availability for them, and not too many predators, but if you get changes in even coastal currents, and sometimes the offshore currents as well, that can have a larger impact on some of the fish stocks too. Thank you. And finally, just a question for Matt Aaron. With regards to AMOC, the worst case scenario, what are the implications for Irish sea fisheries in a worst case scenario, if that were to manifest? Yeah, so the worst case scenario, that would be, of course, that we have really a strong decline of the AMOC till the end of the century, and that could even result in some local cooling around Ireland, because I have to explain, of course, that the AMOC acts like a conveyor belt, transporting heat from the Gulf of Mexico towards Ireland, and of course, if that's slowing down very strongly, like in this worst case scenario, then we could, especially in winter, have cooling of the atmosphere that will then, of course, affect the ocean conditions as well. So especially in winter, but in a very strong scenario, could even happen in summer, that it rather slightly cools than warms. So that would be the worst case scenario. Thank you very much. Deputy McLaughlin.