ASC Theme Session B preview: Vincent Saba on climate change and how life in the ocean responds

Theme Session B co-convener Vincent Saba discusses the challenges involved with the prediction of climate change and how marine organisms react to it.
Published: 1 September 2013

​​​​​​​​​​​​​​​Over 100 submissions were made for Theme Session B's 50 oral presentation slots. Why such interest?

It (climate change and marine resource responses) seems to be a hot research topic right now – both in terms of future climate change and contemporary climate variability. There is much uncertainty about how we think fish populations will respond. Then the tricky part is that we must consider natural climate variability, so it's very hard to attribute how much of the biological change that we see now is anthropogenically caused and how much is due to natural changeability along with the synergies between fishing, management, multi-species interactions, and so on. It's a very complicated task.

Isn't there something of a difference of opinion on how best to project marine resource responses?

I think some of the differences in the responses that people are projecting are reflected in how their specific research shows how a species or group of species may react.

One example is the published papers suggesting ubiquitous species range shifts; fish are adapted to certain water temperatures, be it cold or warm, and as ocean temperatures warm, these species will move further north. Colder water species will then be pushed essentially to what were the northern limits of their range, which will expand further north – and vice-versa in the southern hemisphere.

There are other studies that show that maybe we won't really see a major range shift, just local extinctions and recolonizations - and the ranges will generally be the same. These studies are based on observed data. I guess you could say the jury's still out. But from a general physiological perspective, one would expect to see some range shift in some of these fishes, because temperature does play an important role in where marine animals are found.

Also a question to ask is - will we actually see new fisheries open up in areas that were once inactive?

How much do projections of climate change and marine organism responses differ between fisheries and whole ecosystems?

This (ecosystem perspective) is something that's relatively new in fisheries management. Most fisheries are managed on a single-species basis, and in the U.S. we're trying to move towards this ecosystem-based management. It's becoming clearer that, in terms of climate change, we have to consider the whole ecosystem and not just the effect of warming temperatures on one particular species.

If one species moves north and one south, you'll have new species interactions that have to be accounted for; on top of that you have to understand what's happening with the lower trophic levels – the phytoplankton at the base of the foodweb – combined with changes in fisheries, management, and human behaviour. All these factors acting synergistically – all essentially part of the ecosystem. We consider the socio-economic component critical. Changes in human behaviour have to be considered.

Could you tell us about your previous research on the leatherback turtle and the importance of this species?

The sea turtles are very interesting. They're kind of in their own class compared to other marine animals, the main reason being their terrestrial life-history phase and laying of eggs on dry land substrate. Because of this, they're under a different sensitivity in the sense that both the ocean and terrestrial conditions can affect their response to climate change whereas with cod or herring for example it's primarily what's happening in the ocean – aside from pollution and coastal run-off.

Are you expecting a lively discussion at the ASC?

Indeed. It seems to work well when you have common themes and the speakers together for a post-presentation panel discussion. We hope to have engaging discussions after each set of talks.

​As well as being involved with Theme Session B, Vincent Saba will also present a paper in Theme Session M​ on mechanisms linking ​physical climate and ecosystem change.​​​​ Theme Session B runs 24-26 September in Harpa's Norðurljós room​

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ASC Theme Session B preview: Vincent Saba on climate change and how life in the ocean responds

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