Global warming

Ozone layer depletion (leading to increased UV penetration)

Even in the relatively short term, global warming by the anticipated 1-3°C within the next century, could have an effect on distribution of the kelp species that occur in the UK. For example, Laminaria ochroleuca could extend its distribution northwards up the western coasts of the British Isles (see section I.C). Some research work has been undertaken on the effects of the periodic short-term temperature anomalies known as El Niño which impact on the kelps of the western Pacific (see section IV.B.2). Unfortunately, global warming effects span multiple generations of scientists and governments and the need for very long term monitoring and research has only recently been appreciated.

None known

None known

Studies on the effects of UV-radiation on macroalgae have been rather scattered, both geographically and taxonomically (Dring et al., 1996). Germination of zoospores and the growth of gametophytes in several Laminaria spp. were reduced after exposures of more than 1 h and gametophyte photosynthesis did not recover after exposures longer than 4 h. Although photosynthesis in sporophytes was reduced after exposure, recovery took place during the following 24 h period. Sensitivity to UV decreased from gametophyte to sporophyte and with increasing age of the sporophyte (Dring et al., 1996). Some effects of increased UV-A and UV-B on the survival and physiology of other species of seaweeds have also been investigated (see Lüning, 1990). Changes in survival and growth patterns in natural kelp populations as a response to increased UV-radiation have not been monitored. UV light has been implicated in the kelp disease of infection with the brown algal endophyte Streblonema aecidioides (Schaffelke et al., 1996). This causes deformation of host thalli, but damage was worse at 2 m than at 5 m, and this was interpreted as being due to lower levels of UV at 5 m depth.

None known

None known

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