Kelp Forest

Scotlands Living Landscapes

• Foreword
• Introduction
• What is kelp and where is it found?
• Why kelp forests are important in Scottish coastal waters
• Scottish kelp plants
• Light – the critical factor
• Oarweed forests
• Cuvie forests
• Kelp parks
• Beyond the kelp zone
• Kelp productivity
• Uses of Kelp
• Kelp harvesting
• Afterword

Kelp productivity

After kelp forests have been hit by winter storms, the adjacent shore is covered by a brown carpet of glistening plants that have been ripped off the sea bed by the force of the waves. All this material eventually rots and enters the marine food web.

Kelps contribute organic material to the food web in other ways. Waves continually erode the tips of kelp blades, releasing flakes of plant matter. Every spring each cuvie plant sheds its blade from the previous year; an enormous input of detritus into the marine ecosystem, when the size of kelp forests is taken into account. In addition to the huge volume of rotting foliage produced by kelp forests, individual plants secrete as much as 40% of their net organic production directly into the sea. The productivity of kelp forests has been compared to the level of productivity found in a wheat field on land.

This huge amount of organic material is utilised by the animals of the kelp forest and, due to the action of waves and currents, by animals in other parts of the sea. Some animals, such as urchins, graze directly on kelp fragments. Bacteria absorb dissolved organic matter and in turn are eaten by filter-feeding invertebrates. Single-celled animals, small crustaceans, worms and molluscs trap minute particles of detritus. These, in turn, fall prey to larger animals such as fish and starfish.

The production of organic matter by kelp plants provides much of the fuel that drives the machinery of the inshore food web. Without the food source provided by kelp detritus and dissolved organic matter, inshore coastal waters would contain far fewer animals.