OVER THE PAST 150 YEARS, seawater temperatures in the north-east Atlantic have risen by 0.5-1C. Coastal water temperatures in Scotland rose by about 1ÂC between 1970-1998 alone. By 2100 seawater temperatures are, on average, expected to be 2ÂC higher than todays .
These are the facts. Im not saying that youll be using shortie wetsuits next summer in Britain, but temperature increases, together with alterations in water types around our coasts, are likely to change our wildlife.
Last summer, triggerfish seemed to be invading our shores from the south. This distinctive fish was seen in high numbers and at many locations where it had not been observed before. The first barracuda caught in British waters was recorded in September off Cornwall. In December a Mediterranean slipper lobster was caught in the Isles of Scilly, and a lot more sunfish than usual were noted.
On the downside, the abundance of northern tortoiseshell limpets has declined to the point at which they can rarely be found now in Ireland.
Predicting which species might change in their distribution and abundance as a result of seawater warming is not easy.
Crustaceans with a southern distribution are likely to spread northwards quite rapidly. Their larvae usually live in plankton for many weeks, but reach maturity and settle only if water temperatures are sufficiently high. So look out for spiny spider crabs in Shetland.
On the other hand, the larvae of sea fans probably spend a very short time in open water and settle near their parent colony. Pink sea fans (rare white individuals are also seen in Britain) are therefore unlikely to make the jump from their current northern limits in Northern Ireland to Scotland, and perhaps not from Pembrokeshire to North Wales.
The abundance of certain south-western marine species will increase as reproduction becomes more successful.
Perhaps we will see higher numbers of sunset corals where they already occur (another species with short-lived larvae) and perhaps crawfish will make a comeback (though tangle nets might continue to catch them before you do).
As for northern species, such as the small white sea fan that occurs off Scotlands west coast, and the stone crab commonly seen in north-west Scotland and Shetland, while established individuals will live on in warmer temperatures, recruitment of new individuals is likely to decline. Some species will be lost from British waters.
We are likely to gain more species than we lose, even though the Channel will be a significant barrier to the spread of larvae from France.
Changes in our marine life are not all temperature-linked. The idea that the abundance of a species can differ enormously from year to year or between blocks of years, and at intervals of several decades, is well-established for the open seas.
More than 30 years ago, Sir Frederick Russell observed that the late planktonic stages of fish (and larvae of other species, especially crabs, lobsters and similar crustaceans) were very abundant in the plankton off Plymouth in the 1920s, declined in the Ô30s, and stayed low until somewhere around 1965, when a marked increase occurred.
Although a decline occurred a few years later, the more productive waters that supported the increased abundance of fish and crustacean larvae have returned in recent years, perhaps heralding better prospects for reproductive success in many seabed species.

How can you help
To assist marine biologists in tracking change, we need to establish a biological baseline of species observations. Our successors will then be able to compare this with the situation, say, 100 years from now.
Many of the species likely to change are conspicuous and easily identified. So the Marine Life Information Network (MarLIN), run by the Marine Biological Association to provide information for marine-environment management, protection and education, has put together the Sealife Survey programme with funding from WWF UK and the PADI Project AWARE (UK).
With the help of Diver and its readers, we have selected underwater species from the Sealife Survey programme that we believe divers will be able to recognise, and that are likely to change in their distribution and abundance as a result of climate change.
The following pages show species we would like you to look out for and record. This ID guide can also be downloaded from the MarLIN website, which shows further plants and animals, including intertidal and non-native species. But you can report sightings of any seabed species you consider interesting.
You can submit your records through the MarLIN website, by post or even by phone from your dive boat (we will be on the look-out for dodgy records, and must be able to contact you for verification).
There are no prizes but, who knows, you might be the first person to find pink sea fans in North Wales or small triggerfish (a sign of local breeding) in Britain! Validated records are contributed to the UK National Biodiversity Network to ensure that they are retained into the distant future.

INFORMATION SOURCES
BRITISH MARINE LIFE STUDY SOCIETY, website: ourworld.compuserve.com/ homepages/BMLSS
JOINT NATURE CONSERVATION COMMITTEE (information on distribution of marine wildlife around Britain), www.jncc.gov.uk/mermaid
MarClim PROGRAMME (studies to clarify how our marine wildlife has changed and to establish a basis for tracking further change, especially in intertidal species), www.mba.ac.uk/marclim
MARINE LIFE INFORMATION NETWORK (MarLIN, part of the Marine Biological Association), www.marlin.ac.uk
NATIONAL BIODIVERSITY NETWORK (sharing information on wildlife across the UK), www.nbn.org.uk / www.searchnbn.net
MARINE CONSERVATION SOCIETY (for ID books), www.mcsuk.org/books. To take part in marine-life surveys, contact the Seasearch programme at the MCS, 9 Gloucester Road, Ross-on-Wye, HR9 5BU (tel: 01989 566017, e-mail: info@mcsuk.org, website: www.seasearch.org.uk)
SCOTTISH NATURAL HERITAGE (for brochure describing likely effects of climate change on seabed species in Scotland), Dr John Baxter, SNH, Anderson Place, Edinburgh EH2 5NP, e-mail: john.baxter@snh.gov.uk
This is where you come in
Divers are asked to record their observations of the animals and plants shown on these pages. The information will contribute to understanding the current distribution of seabed species likely to change in distribution and abundance around Britain and Ireland as a result of climate change.

Please note the following information as a minimum:
  • Name of species
  • Where you saw it (latitude and longitude or OS grid reference preferred, but give place names anyway)
  • Date and time of sighting
  • Your name and contact details
If possible include the habitat in which the species occurred, number seen and any interesting behaviour. For anything unusual, expect to produce a photo, video footage or be able to say precisely why you think it is what you say it is.
MarLIN offers a first point of contact regarding any interesting sealife record. To enter your record, or to obtain extra copies of the species ID card, recording forms and a list of marine-recording schemes, you can contact MarLIN: online - www.marlin.ac.uk/sealifesurvey; by e-mail - marlin@mba.ac.uk; by post - Sealife Survey, Marine Biological Association, Plymouth PL1 2PB; or by phone - 01752 255026. The Sealife answer-machine service, supported by PADI Project AWARE (UK), operates round the clock.