Warming effect 'not as drastic'

Scotland's marine life is changing

The effects of climate change on Scotland's marine habitats may not be as drastic as some forecasts have predicted.

The results of a study carried out for Scottish Natural Heritage (SNH) by the Marine Biological Association indicates that a large number of species will be relatively unaffected by temperature changes.

However, the northern sea fan worm could disappear from Scottish waters and a species of barnacle which is currently rare on the east coast of Scotland may spread down the east coast by the year 2100.

Computer models were used to examine the effects of inshore sea temperature changes on 23 key marine species.

Losing spiecies

Researchers have predicted that some species will extend north or eastwards around the coast as temperatures increase by up to two degrees C, while others will decrease and could die out altogether.

The study showed where marine species would expand given their current biology and distribution.

It also took into account factors such as whether the species in question can swim, walk or drift, the optimum temperature for larvae to develop and the presence of geographical barriers.

This has helped us to determine which key species should be monitored with regard to climate change

John Baxter
SNH

John Baxter, SNH maritime group manager, said: "This pilot project has highlighted that there are potentially a number of scenarios that could arise as a result of the sea temperature rise.

"We will lose several species and will gain some species but there are not the major changes that some people have predicted.

"It has also helped us to determine which key species should be monitored with regard to climate change in the new Britain and Ireland study."

The pilot project results suggest beds of maerl and horse mussels, which are only found in Scotland or are particularly well-developed here, are especially vulnerable to climate change.

Also, some extremely sheltered deep lochs may be more prone to de-oxygenation as higher temperatures contribute to isolation of bottom waters.

Other factors

But other species will fare better, such as Montagu's punctate barnacle, which currently thrives along the west coast of Britain, but is rare on the east.

It would be likely to creep relatively unchecked down the east coast if the sea warmed by one or two degrees celcius, according to the study.

Likewise, the limpet Patella depressa and the topshell snail Osilinus lineatus, which are largely found south of Scotland, could move steadily northwards.

And other species such as the topshell Gibbula umbilicalis could continue the advance around the north and down the east coast of Scotland.

£1m project

Meanwhile, some species are unlikely to be affected by climate change, since their distribution is influenced by other factors than temperature.

The southern sea fan would probably not reach Scotland from Wales and Northern Ireland because it has a short-lived larva which would not cross the significant geographical barrier of the North Channel.

Similarly, communities of sea anemones, lamp shells, fan worms and sea squirts, which are characteristic of sea lochs, primarily seek sheltered environments and may not be influenced by climate change.

The research has sparked a £1m collaborative project in Britain and Ireland, including SNH, which will use site monitoring of key sensitive species to examine the effects of climate change on the marine world.