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Publication - Consultation Paper

Wild seaweed harvesting: strategic environmental assessment - environmental report

Published: 22 Nov 2016
Part of:
Marine and fisheries
ISBN:
9781786526229

Investigates the sustainability and potential environmental impacts of wild seaweed and seagrass harvesting, maerl extraction and removal of beach-cast seaweed.

263 page PDF

10.2MB

263 page PDF

10.2MB

Contents
Wild seaweed harvesting: strategic environmental assessment - environmental report
16. Appendix C: Background Information on Seaweeds and Seagrasses

263 page PDF

10.2MB

16. Appendix C: Background Information on Seaweeds and Seagrasses

Table C1: Main seaweed and seagrass species found in Scotland

Species Name

Recent Other Species Names

Common Name

General Location on Shore

Growth Cycle/ Seasonal Variability

Nature of Resource

Brown Seaweeds

Wracks or rockweeds

Ascophyllum nodosum

Egg wrack / knotted wrack / knobbed wrack

Found in mid eulittoral areas and is generally typical of sheltered shores.

The species is very long lived and has low recruitment. Growth rate is very slow in germlings but increases as the plant ages. During the first year growth takes place at 0.2 cm per year, rising to 1.5 cm per year in the second year. The holdfasts of Ascophyllum nodosum are thought to persist for several decades from which new fronds regenerate.

Living

Pelvetia canaliculata

Channel(led) wrack/ sea sprigs

Grows only in upper eulittoral on sheltered shores or in sheltered areas of more exposed shores.

A perennial species; it is at least two years old before it reaches maturity, and has a life span of up to 4 or 5 years, growing 3 to 4 cm per year.

Living

Fucus vesiculosus

Bladder wrack/ rock kelp

Grows mainly in mid eulittoral.

As it can survive in a wide range of exposures, it can grow more than 0.5 cm per week in optimum sheltered summer conditions, eventually reaching sizes of up to 1.5 and 2 metres, and achieve a life span of up to 5 years.

Living

Fucus serratus

Serrated wrack/ toothed wrack/ saw wrack

Grows mainly on lower eulittoral.

Its growth rate varies considerably depending on environmental conditions, but can range from 4 to 12 cm per year. Fucus serratus plants may become detached and lost to winter storms. It lives for 2 to 5 years.

Living

Fucus spiralis*

Spiral wrack / spiralled wrack

Grows mainly in upper eulittoral in sheltered locations.

It has a life span of 2 to 5 years, and is mature at 2 years. Reproduction usually begins before or during the second year of growth, from the end of winter through spring and into summer.

Living

Himanthalia elongata

Thongweed/ sea spaghetti

Found on open rock platforms mainly on lower eulittoral.

It has a life span of about 18-21 months, and is mature and able to reproduce at 9 months.

Usually annual.

Reproductive fronds, which are the harvested thong-like part of the plant, grow throughout the winter and spring, before summer reproduction. Plant then falls off rock and disintegrates.

Living

Sargassum muticum

Wireweed

Grows mainly on lower eulittoral.

It has a long life span (3 to 4 years) and high growth rate (10 cm per day).

Living

Kelps

Saccharina latissima

Laminaria saccharina

Sweet kombu/ sugar kelp / Atlantic kombu / sea belt

Found in eulittoral/infralittoral fringe.

Although it is present year-round and is considered a perennial with a life span of 2 to 5 years, the blade dies back in the autumn and winter, and re-grows in the late winter and spring. Maximum growth rates have been measured during the late winter and spring with minimum growth during the late summer and autumn in response to the onset of shorter days. The second season tends to exhibit the most growth.

Living

Laminaria hyperborea

Kelp / oarweed / cuvie / tangle

Found in eulittoral/infralittoral fringe.

It is a long-lived perennial species in contrast to other Laminaria species in the upper sublittoral, which have a typical life of about 3 years. In Scotland it has a life span generally of 5 to 7 years, with 12 to 15 year old plants sometimes found. Blade area and stipe length of adults grow rapidly until about 5 years old. In 1-year old Laminaria hyperborea plants however, growth mainly occurred in the lamina in order to maximize the area for photosynthesis in the light limited understorey. Laminaria hyperborea also follows a distinct seasonal growth pattern. Peak growth occurs during winter to spring/summer (November to June) and stops at the end of summer, although metabolic rate remains high. Each November the new blade starts growing below the old one, leaving a distinct collar between the two; the growth continues until around June. Nutrients from the old blade contribute to the growth of the new blade, and the old blade tissue is shed in the spring and early summer. A completely new frond is formed each year, unlike the other Laminaria species.

Living and beach-cast

Laminaria digitata

Kombu/ Atlantic oarweed / kelp / tangle / sea girdle

Found in eulittoral/infralittoral fringe.

This perennial species lives for 3 to 6 years, and in some cases reached 10 years. Laminaria digitata grows more slowly from late summer to January, and then experiences rapid growth from February through July. Growth is from the meristem at the junction between the stipe and the frond, rather than the tips.

Living

Alaria esculenta

Dabberlocks / bladder Locks / edible kelp / honeyware

Found on lower eulittoral in subtidal fringe on wave exposed areas.

Its highest seasonal growth rate can reach 20 - 25 cm per month. It is a perennial which can lives up to 7 years in some locations.

Living

Green Seaweeds

Ulva intestinalis

Enteromorpha intestinalis

Aonori/ sea greens/ gutweed/ grass kelp

Found throughout the eulittoral but very common on upper shore

This is a summer annual, decaying and forming masses of bleached white fronds towards the end of the season. Its growth rate is about 0.15-0.25 cm/day.

Ulva lactuca

Sea lettuce

Found throughout the eulittoral but very common on upper shore

It is present year round, but most abundant in summer and autumn.

Living

Red Seaweeds

Chondrus crispus

Carragheen moss / Irish moss

Grows throughout the eulittoral on a variety of surfaces.

This is a perennial seaweed that is present year round. Its fronds typically have a life of two to three years but may live up to six years in sheltered waters. The holdfast is much longer lived and is capable of regenerating new fronds after disturbance.

Living

Mastocarpus stellatus

Gigartina stellata

Often confused with Chondrus crispus and also called Carragheen moss / False Irish moss

Grows throughout the eulittoral on a variety of surfaces.

Complex life cycle and a species that takes on many varied morphologies. Recent molecular studies suggest speciation may be taking place (J. Brodie, NaturalHistory Museum, pers. comm.). Not only do the male and female gametophyte individuals exhibit different morphologies, the tetrasporophyte individual is so completely different that it was originally described as a different species.

Living

Palmaria palmata

Dulse

Grows in the lower eulittoral/infralittoral fringe and can be very abundant.

This is a perennial species with new growth every year, whose holdfast could remain for several years.

Living

Osmundea pinnatifida

Laurencia pinnatifida

Pepper dulse

Found in a variety of habitats on mid and lower shore may be mingled with mats/turfs.

Living

Porphyra umbilicalis

Purple nori / laver/ tough laver

Generally found in the upper eulittoral.

It has a short lifespan, but because is reproduces quickly it can be found throughout the year.

Living

Porphyra purpurea

Purple laver

Occurs generally in the lower eulittoral in very sheltered areas.

This species occurs throughout the year and is an aseasonal annual.

Living

Maerl

Lithothamnion glaciale

maerl

Upper infralittoral.

Little is known about growth rates of this species. It is a slow growing species with recorded growth rates of up to 13 microns per day.

Calcified seaweed

Phymatolithon calcareum

maerl

Upper infralittoral.

This seaweed is extremely slow growing, amassing only about 1 to 2 mm of growth per year, but may live to be over 100 years old.

Calcified seaweed

Sea Grasses

Zostera marina

Common eelgrass/ seawrack

Grows on lower eulittoral and upper infralittoral.

Zostera spp. are perennials but may act as annuals under stressful conditions. Perennial populations show a seasonal changes in leaf growth, the long leaves found in summer are replaced by shorter, slow growing leaves in winter. The growth rates of perennial populations is around 5 m/year. Annual populations may expand at 30 m/year in good conditions.

Living and beach-cast

Zostera noltii

Dwarf eelgrass

Grows mainly in mid eulittoral.

New leaves appear in spring and eelgrass meadows develop over intertidal flats in summer, due to vegetative growth. Leaf growth stops in September/October and leaves are shed although Zostera noltii keeps its leaves longer than Zostera marina in winter. In the following season, regrowth occurs from the remaining rhizomes.

Its growth is rapid with reported growth rates of around 0.2 cm/day (winter minimum) to ca 0.8-0.9 cm/day (summer maximum) in the Mediterranean (with winter temperature of 12 °C and summer maximum temperature of 23.2 °C).

Living and beach-cast

Ruppia spp.

Widgeonweeds / tasselweed

Grows in the upper infralittoral.

Wigeongrass in southwest Canada can germinate and produce mature drupelets in about 2 months whereas, in southern France, other annual plants take as long as 5 months to mature. In climates where spring and autumn growth peaks occur, plants probably grow faster in the spring.

Living and beach-cast

*This probably encompasses three species of wrack, of which Fucus spiralis and another species (currently called Fucus guiryi) occur in Scotland. These are likely to be ecologically distinct with the real F. spiralis occurring in the upper eulittoral and in sheltered places.

Table C2: Key EUNIS habitats and spatial data layers comprising the broad seaweed and seagrass groups

Broad Group

EUNIS Habitat Codes

EUNIS Habitat Name

Spatial Data Layer Source(s)

Wracks

A1.15

Fucoids in tide-swept conditions

MESH, GeMS

A1.151

[ Ascophyllum nodosum], sponges and ascidians on tide-swept mid eulittoral rock

MESH, GeMS

A1.152

Fucus serratus, sponges and ascidians on tide-swept lower eulittoral rock

GeMS

A1.153

[ Fucus serratus] with sponges, ascidians and red seaweeds on tide-swept lower eulittoral mixed substrata

MESH, GeMS

A1.2

Moderate energy littoral rock

MESH

A1.21

Barnacles and fucoids on moderately exposed shores

MESH

A1.2142

[ Fucus serratus] and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders

MESH

A1.3

Low energy littoral rock

MESH

A1.31

Fucoids on sheltered marine shores

MESH

A1.312

[ Fucus spiralis] on sheltered upper eulittoral rock

MESH

A1.313

[ Fucus vesiculosus] on moderately exposed to sheltered mid eulittoral rock

MESH

A1.3132

[ Fucus vesiculosus] on mid eulittoral mixed substrata

MESH

A1.314

[ Ascophyllum nodosum] on very sheltered mid eulittoral rock

MESH

A1.3141

[ Ascophyllum nodosum] on full salinity mid eulittoral rock

MESH

A1.3142

[ Ascophyllum nodosum] on full salinity mid eulittoral mixed substrata

MESH

A1.32

Fucoids in variable salinity

MESH

A1.321

[ Pelvetia canaliculata] on sheltered variable salinity littoral fringe rock

MESH

A1.324

[ Ascophyllum nodosum] and [ Fucus vesiculosus] on variable salinity mid eulittoral rock

MESH

A1.325

[ Ascophyllum nodosum] ecad. [ mackaii] beds on extremely sheltered mid eulittoral mixed substrata

MESH, GeMS

A1.327

[ Fucus ceranoides] on reduced salinity eulittoral rock

MESH

A2.4

Littoral mixed sediments

MESH

A3.22

Kelp and seaweed communities in tide-swept sheltered conditions

MESH

A3.3

Atlantic and Mediterranean low energy infralittoral rock

MESH

A3.34

Submerged fucoids, green or red seaweeds (low salinity infralittoral rock)

MESH, GeMS

A3.341

Mixed fucoids, [ Chorda filum] and green seaweeds on reduced salinity infralittoral rock

MESH, GeMS

A3.342

[ Ascophyllum nodosum] and epiphytic sponges and ascidians on variable salinity infralittoral rock

GeMS

A3.344

[ Fucus ceranoides] and [ Enteromorpha] spp. on low salinity infralittoral rock

MESH, GeMS

Kelps

A1.3

Low energy littoral rock

MESH

A3.1

Atlantic and Mediterranean high energy infralittoral rock

MESH, EUSeaMap

A3.11

Kelp with cushion fauna and/or foliose red seaweeds

MESH

A3.113

[ Laminaria hyperborea] forest with a faunal cushion (sponges and polyclinids) and foliose red seaweeds on very exposed infralittoral rock

MESH, GeMS

A3.115

[ Laminaria hyperborea] with dense foliose red seaweeds on exposed infralittoral rock

MESH, GeMS

A3.1151

[ Laminaria hyperborea] forest with dense foliose red seaweeds on exposed upper infralittoral rock

GeMS

A3.1152

[ Laminaria hyperborea] park with dense foliose red seaweeds on exposed lower infralittoral rock

MESH, GeMS

A3.12

Sediment-affected or disturbed kelp and seaweed communities

MESH

A3.122

[Laminaria saccharina] and/or [Saccorhiza polyschides] on exposed infralittoral rock

MESH

A3.123

[ Laminaria saccharina], [ Chorda filum] and dense red seaweeds on shallow unstable infralittoral boulders and cobbles

MESH

A3.125

Mixed kelps with scour-tolerant and opportunistic foliose red seaweeds on scoured or sand-covered infralittoral rock

MESH

A3.126

[ Halidrys siliquosa] and mixed kelps on tide-swept infralittoral rock with coarse sediment

MESH, GeMS

A3.2

Atlantic and Mediterranean moderate energy infralittoral rock

EUSeaMap

A3.21

Kelp and red seaweeds (moderate energy infralittoral rock)

MESH

A3.2111

[ Laminaria digitata] on moderately exposed sublittoral fringe bedrock

MESH

A3.212

[ Laminaria hyperborea] on tide-swept, infralittoral rock

MESH, GeMS

A3.2121

[ Laminaria hyperborea] forest, foliose red seaweeds and a diverse fauna on tide-swept upper infralittoral rock

MESH, GeMS

A3.2122

[ Laminaria hyperborea] park with hydroids, bryozoans and sponges on tide-swept lower infralittoral rock

GeMS

A3.213

[ Laminaria hyperborea] on tide-swept infralittoral mixed substrata

GeMS

A3.2131

[ Laminaria hyperborea] forest and foliose red seaweeds on tide-swept upper infralittoral mixed substrata

MESH, GeMS

A3.2132

[ Laminaria hyperborea] park and foliose red seaweeds on tide-swept lower infralittoral mixed substrata

MESH, GeMS

A3.214

[ Laminaria hyperborea] and foliose red seaweeds on moderately exposed infralittoral rock

MESH

A3.2141

[ Laminaria hyperborea] forest and foliose red seaweeds on moderately exposed upper infralittoral rock

MESH, GeMS

A3.2142

[ Laminaria hyperborea] park and foliose red seaweeds on moderately exposed lower infralittoral rock

MESH, GeMS

A3.2143

Grazed [ Laminaria hyperborea] forest with coralline crusts on upper infralittoral rock

MESH, GeMS

A3.2144

Grazed [ Laminaria hyperborea] park with coralline crusts on lower infralittoral rock

MESH, GeMS

A3.22

Kelp and seaweed communities in tide-swept sheltered conditions

MESH

A3.221

[ Laminaria digitata], ascidians and bryozoans on tide-swept sublittoral fringe rock

MESH, GeMS

A3.222

Mixed kelp with foliose red seaweeds, sponges and ascidians on sheltered tide-swept infralittoral rock

MESH, GeMS

A3.223

Mixed kelp and red seaweeds on infralittoral boulders, cobbles and gravel in tidal rapids

MESH, GeMS

A3.224

[ Laminaria saccharina] with foliose red seaweeds and ascidians on sheltered tide-swept infralittoral rock

MESH

A3.3

Atlantic and Mediterranean low energy infralittoral rock

MESH

A3.31

Silted kelp on low energy infralittoral rock with full salinity

MESH, EUSeaMap

A3.312

Mixed [ Laminaria hyperborea] and [ Laminaria saccharina] on sheltered infralittoral rock

MESH

A3.3121

Mixed [ Laminaria hyperborea] and [ Laminaria saccharina] forest on sheltered upper infralittoral rock

MESH

A3.313

[ Laminaria saccharina] on very sheltered infralittoral rock

MESH

A3.3132

[ Laminaria saccharina] forest on very sheltered upper infralittoral rock

MESH

A3.314

Silted cape-form Laminaria hyperborea on very sheltered infralittoral rock

MESH

A3.32

Kelp in variable or reduced salinity

GeMS

A3.322

[ Laminaria saccharina] and [ Psammechinus miliaris] on variable salinity grazed infralittoral rock

MESH, GeMS

A3.323

Laminaria saccharina with Phyllophora spp. and filamentous green seaweeds on variable or reduced salinity infralittoral rock

GeMS

A5.52

Kelp and seaweed communities on sublittoral sediment

MESH

A5.521

[ Laminaria saccharina] and red seaweeds on infralittoral sediments

GeMS

A5.5211

Red seaweeds and kelps on tide-swept mobile infralittoral cobbles and pebbles

GeMS

A5.5212

[ Laminaria saccharina] and robust red algae on infralittoral gravel and pebble

GeMS

A5.5213

[ Laminaria saccharina] and filamentous red algae on infralittoral sand

GeMS

A5.5214

[ Laminaria saccharina] with red and brown seaweeds on lower infralittoral muddy mixed sediment

GeMS

A5.522

[ Laminaria saccharina] and [ Chorda filum] on sheltered upper infralittoral muddy sediment

MESH, GeMS

A5.523

[ Laminaria saccharina] with [ Psammechinus miliaris] and/or [ Modiolus modiolus] on variable salinity infralittoral sediment

GeMS

A5.524

[ Laminaria saccharina], [ Gracilaria gracilis] and brown seaweeds on full salinity infralittoral sediment

GeMS

Green seaweeds

A1.3

Low energy littoral rock

MESH

A2.1

Littoral coarse sediment

MESH

A2.4

Littoral mixed sediments

MESH

A2.8

Features of littoral sediment

MESH

A2.821

Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata

MESH

A3.3

Atlantic and Mediterranean low energy infralittoral rock

MESH

A3.323

[ Laminaria saccharina] with [ Phyllophora] spp. and filamentous green seaweeds on variable or reduced salinity infralittoral rock

MESH, GeMS

A3.34

Submerged fucoids, green or red seaweeds (low salinity infralittoral rock)

GeMS

A3.341

Mixed fucoids, [ Chorda filum] and green seaweeds on reduced salinity infralittoral rock

MESH, GeMS

A3.344

[ Fucus ceranoides] and [ Enteromorpha] spp. on low salinity infralittoral rock

MESH, GeMS

A5.528

Filamentous green seaweeds on low salinity infralittoral mixed sediment or rock

MESH

A5.5343

[ Ruppia maritima] in reduced salinity infralittoral muddy sand

MESH

Red seaweeds

A1.3

Low energy littoral rock

MESH

A3.1

Atlantic and Mediterranean high energy infralittoral rock

EUSeaMap

A3.11

Kelp with cushion fauna and/or foliose red seaweeds

MESH

A3.2

Atlantic and Mediterranean moderate energy infralittoral rock

EUSeaMap

A3.21

Kelp and red seaweeds (moderate energy infralittoral rock)

MESH

A3.2132

[ Laminaria hyperborea] park and foliose red seaweeds on tide-swept lower infralittoral mixed substrata

GeMS

A3.222

Mixed kelp with foliose red seaweeds, sponges and ascidians on sheltered tide-swept infralittoral rock

GeMS

A3.223

Mixed kelp and red seaweeds on infralittoral boulders, cobbles and gravel in tidal rapids

GeMS

A3.3

Atlantic and Mediterranean low energy infralittoral rock

MESH

A3.321

Codium spp. with red seaweeds and sparse Laminaria saccharina on shallow, heavily-silted, very sheltered infralittoral rock

GeMS

A3.33

Mediterranean submerged fucoids, green or red seaweeds on full salinity infralittoral rock

MESH

A3.34

Submerged fucoids, green or red seaweeds (low salinity infralittoral rock)

MESH, GeMS

A3.344

[ Fucus ceranoides] and [ Enteromorpha] spp. on low salinity infralittoral rock

GeMS

Calcified seaweeds (namely maerl)

A5.51

Maerl beds

MESH, GeMS

A5.511

[ Phymatolithon calcareum] maerl beds in infralittoral clean gravel or coarse sand

MESH, GeMS

A5.5111

[ Phymatolithon calcareum] maerl beds with red seaweeds in shallow infralittoral clean gravel or coarse sand

MESH

A5.5112

[ Phymatolithon calcareum] maerl beds with [ Neopentadactyla mixta] and other echinoderms in deeper infralittoral clean gravel or coarse sand

MESH

A5.512

[ Lithothamnion glaciale] maerl beds in tide-swept variable salinity infralittoral gravel

MESH, GeMS

Seagrasses

A2.61

Seagrass beds on littoral sediments

MESH, GeMS

A2.6111

[ Zostera noltii] beds in littoral muddy sand

MESH

A5.5

Sublittoral macrophyte-dominated sediment

MESH

A5.53

Sublittoral seagrass beds

MESH, GeMS

A5.5331

[ Zostera marina]/[ angustifolia] beds on lower shore or infralittoral clean or muddy sand

MESH, GeMS

A5.5343

[ Ruppia maritima] in reduced salinity infralittoral muddy sand

MESH, GeMS

Beach-cast seaweeds/ seagrasses

A2.21

Strandline

MESH

A2.211

Talitrids on the upper shore and strandline

MESH


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