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Substratum
The kelp species in the UK are most frequently found attached to
submerged bedrock. However, given adequate water movement in the form of tidal currents
rather than wave action, large kelp plants may frequently be found attached to cobbles and
pebbles. When attached to small solid objects, the life-span of the plant becomes size-
limited, since larger plants are more easily washed from their original location if only
attached to a small stone. Kelps are found in almost all locations where some form of hard
substratum is available within the euphotic zone in UK waters; see table below.
| Substrata colonised by kelp species in the UK |
Kelp species |
substrata |
| Alaria esculenta |
bedrock, stable boulders, cobbles, pebbles on large gravel,
pontoons & moorings, man-made structures. Not in areas where there is sand scouring or
siltation. |
| Laminaria digitata |
bedrock, stable boulders, pebbles on large gravel, stones on
stable mud or sand, pontoons & moorings, other man-made structures. Not in areas
subject to intense sand scouring but can be found in areas of siltation. |
| Laminaria hyperborea |
bedrock, stable boulders, pebbles on large gravel, deeper
parts of pontoons and moorings, other man-made structures. Not in areas subject to sand
scouring but can sometimes be found in areas of siltation. |
| Laminaria saccharina |
bedrock, stable boulders, pebbles on large gravel, stones on
stable mud or sand, pontoons & moorings, other man-made structures. Not in areas
subject to severe sand scouring but can be found in areas of siltation. |
| Saccorhiza polyschides |
bedrock, stable boulders, pebbles on large gravel, pontoons
& moorings, other man-made structures. Not in areas subject to sand scouring but can
be found in areas of siltation. |
| Undaria pinnatifida |
at present, mainly on man made structures, but may spread to
bedrock, stable boulders |
Where kelp species colonise unstable substrata, the populations are
ephemeral. When the lamina reaches a certain area in relation to the mass of the item to
which the plant is attached, the plant will be moved by the tide, wave action and current
at the site. This frequently results in the plant being removed from the photic zone,
either being cast ashore or deposited in deeper water, with the substratum exhibiting a
dynamic fluctuation of colonisation and loss of kelp plants. On the shores of the NE
Pacific, individuals of the annual kelp species Nereocystis luetkeana utilise the
local water movement to migrate to deeper water as the plant increases in size (C. Hurd,
pers.comm.).
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References
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