Intertidal seaweeds



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In situ sampling procedure and quality index calculation

for the EQ "intertidal seaweeds"
CCO

Cover - Characteristic species - Opportunistic species
WFD - coastal waters - GIG NEA

Erwan Ar Gall & Michel Le Duff
IUEM (European Institute for Marine Studies) – UBO (University of Western Brittany - Brest)

Technopôle Brest -Iroise

29280 Plouzane

Brittany, France


2007

(November 2010 version)
1. In situ sampling procedure


    1. General points


Monitoring sites: shores exhibiting essentially bedrock surfaces (reduced surface of boulders, sand, mud or gravels, large boulders being acceptable at lowest levels), if possible within the range 30 – 100 m width and 100 – 300 m length, and comprising most of the intertidal belts occurring in a given area.
Sampling period: from early March to late July, once every three years for each site.
Replicates : both diversity and structure of each macroalgal community (corresponding to a given belt) are noted on the field within three 33 cm X 33 cm squares per spot, determined by drawing lots, within three 1.65 m X 1.65 m permanent spots per belt, so within 9 squares and 0.9 m2 per belt and per year.

Points are materialized on the soil by a removable 1.65 m X 1.65 m frame comprising 5 X 5 squares.


A field sheet is annexed to the document.
1.2. Global plant covering of the belts (covering percentages, ca. a few %)

Pelvetia canaliculata (Pc) :

Fucus spiralis (Fspi) :

Ascophyllum nodosum (An) / Fucus vesiculosus (Fves) :

Fucus serratus (Fser) / Rhodophyceae :

Himanthalia elongata (He) / Bifurcaria bifurcata (Bb) / Rhodophyceae :

Laminaria digitata (Ld) / Laminariales :
NB : in Brittany (and Armorican Massif, including western Channel waters and North of the Bay of Biscay), all sites exhibit at least 5 of these 6 typical belts, the lowest of them being reached only during great tides (tide coefficients > 95). In areas outside Brittany, the minimal number of belts may be drastically reduced (e.g. 2 levels in the Basque Country).

Even in Brittany, belts may overlap and then must be grouped (e.g. no He belt and no Ld belt but a Rhodophyceae / Laminariales level)

An / Fves, Fser / Rhodophyceae, He / Bb / Rhodophyceae, Ld / Laminariales are usually named An, Fser, He and Ld, respectively.
1.3. Surface of each bathymetric level * (m2)
Pelvetia canaliculata (Pc) :

Fucus spiralis (Fspi) :

Ascophyllum nodosum (An) / Fucus vesiculosus (Fves) :

Fucus serratus (Fser) / Rhodophyceae :

Himanthalia elongata (He) / Bifurcaria bifurcata (Bb) / Rhodophyceae :

Laminaria digitata (Ld) :

*: for each level, all bedrock surfaces potentially covered by seaweeds (dominating species or other species) must be taken into account, at the exclusion of large sand / gravel / small boulder areas.
1.4. Observations in the sampling squares
In each square, cover of all characteristic and opportunist species identified on the field, expressed as covering percentages as follows:

0 - 5 %, > 5 -25 %, > 25% - 50%, >50 % - 75 %, > 75 % - 100 %


2. Quality index calculation for EQ intertidal macroalgae

in coastal waters

This index has been adapted to the Breton shore line and more largely to Atlantic and Channel coasts of France from the CFR index developed in Spain. It takes into account the contribution of each macroalgal community, referred to as a belt, to the global plant covering of a given intertidal rocky shore (maximum 40 points), the number of characteristic species (maximum 30 points) and the total cover of opportunist species in every belt (maximum 30 points). The index corresponds therefore to a notation on 100 summarizing the points obtained in the calculation of the above three sub-indexes.

N.B.: only crude data are collected on the field (cf. field sheet) and all calculations can be done afterwards.

2.1. Global plant covering
All levels of the intertidal zone are concerned, and the relative importance of each belt is converted into points using a sub-index table taking into account the rank of each belt determined from its surface (bedrock) within the limits of the site and then the covering percentage of the vegetation in the corresponding area.

Points obtained in all belts are cumulated in order to give a global value for the site out of 40. If one belt lacks (or more), a rule of three must be applied to get the notation out of 40. When more than 50 % of the substratum surface is unconsolidated (sand, mud, gravels, small boulders) or friable (stratified limestone), the level can be disqualified and so not taken into account. However, either a high turbidity or a 1 – 2cm sand layer over the rocky substrate cannot be considered as disqualifying, since Rhodophyceae often replace dominating Phaeophyceae in those cases.


Each belt is therefore ranked according to the importance of its surface. In that way, it is possible to take into account the relative extension of the plant covering in each belt, while enabling a simple calculation of the sub-index, using entire numbers and a total not exceeding 40. A maximum of 5 index tables can be used for the calculation, one for each level, following a decreasing expansion ranking. When present, the sixth level (i.e. with the less extended plant - covered surface) shares the same table as the fifth one. When one belt (or more) lacks on the site, a rule of three will be applied to get the notation out of 40.

Index table for the global plant covering of each belt.

(Ranks are based on the potentially plant-covered area)




Rank 1

value

percentage

9

75 – 100 %

7

50 – 75 %

6

25 – 50 %

5

10 – 25 %

4

5 - 10 %

2

2.5 – 5 %

0

0 – 2.5 %



Rank 2

value

percentage

8

75 – 100 %

7

50 – 75 %

6

25 – 50 %

5

10 – 25 %

3

5 - 10 %

2

2.5 – 5 %

0

0 – 2.5 %




Rank 3

value

percentage

7

75 – 100 %

6

50 – 75 %

5

25 – 50 %

3

10 – 25 %

2

5 - 10 %

1

2.5 – 5 %

0

0 – 2.5 %




Rank 4

value

percentage

6

75 – 100 %

5

50 – 75 %

4

25 – 50 %

3

10 – 25 %

2

5 - 10 %

1

2.5 – 5 %

0

0 – 2.5 %



Ranks 5 & 6

value

percentage

5

75 – 100 %

4

50 – 75 %

3

25 – 50 %

3

10 – 25 %

2

5 - 10 %

1

2.5 – 5 %

0

0 – 2.5 %

2.2. Number of characteristic species occurring on the site


Rather than a global list of characteristic species for a typical shore, the repartition of these species at each level, i.e. in each habitat constituted by belts (linear populations) of structurating Phaeophyceae, has been taken into account. Hereafter are listed from the bottom to the top of the rocky shore the belts occurring on the coasts of both the Channel and the Atlantic Ocean: Laminaria digitata (Ld), Himanthalia elongata - Bifurcaria bifurcata (He + Bb), Fucus serratus (Fser), Ascophyllum nodosum - Fucus vesiculosus (An + Fves), Fucus spiralis (Fspi), Pelvetia canaliculata (Pc). The last two belts are joined here because of their low algal diversity. Beyond that grouping, the relative importance of each belt in the calculation of this sub-index is balanced by an index table adapted to each level, with a given number of characteristic species.
The species taken into account on the field to calculate the index are listed in the table below when they exhibit a minimal cover of 2.5% per belt. Concerning the combined belts Pc and Fspi, species taken into account must cover at least 2.5% in one of these two belts. When species have a heteromorphic life-cycle, surfaces covered by each generation must be added (e.g. Mastocarpus stellatus / Petrocelis cruenta).

Sub-index value = sum of values per belt (or grouped belts) / 5,

when 5 levels occur (at least either Pc or Fspi for Pc + Fspi)

or sub-index value = sum of values per belt / n X 5



when n levels occur (with n < 5)



Pc + Fspi

An + Fves

Fser

He + Bb

Ld

Ascophyllum nodosum

Ascophyllum nodosum

Chondrus crispus

Asparagopsis armata/Falkenbergia

Calliblepharis jubata

Catenella repens

Cladophora rupestris

Cladophora rupestris

Bifurcaria bifurcata

Chondracanthus acicularis

Fucus spiralis

Corallina spp.

Corallina spp.

Calliblepharis jubata

Chondrus crispus

Hildenbrandia rubra

Fucus serratus

Cryptopleura ramosa

Chondracanthus acicularis

Corallina spp.

Lichina pygmaea

Fucus vesiculosus

Fucus serratus

Chondrus crispus

Cryptopleura ramosa

Pelvetia canaliculata

Gelidium spinosum (pulchellum/latifolium)

Gelidium spinosum (pulchellum/latifolium)

Cladophora rupestris

Cystoclonium purpureum

Verrucaria maura

Gelidium pusillum

Gelidium pusillum

Corallina spp.

Himanthalia elongata




Lithophyllum incrustans

Lithophyllum incrustans

Cryptopleura ramosa

Laminaria digitata




Lithothamnion lenormandii

Lithothamnion lenormandii

Cystoclonium purpureum

Laminaria saccharina




Lomentaria articulata

Lomentaria articulata

Gelidium spinosum (pulchellum/latifolium)

Laurencia obtusa/L. hybrida




Mastocarpus stellatus

Mastocarpus stellatus

Himanthalia elongata

Lithophyllum incrustans




Plumaria plumosa

Osmundea pinnatifida

Laurencia obtusa / L. hybrida

Lomentaria articulata




Rhodothamniella floridula

Palmaria palmata

Lithophyllum incrustans

Mastocarpus stellatus







Plumaria plumosa

Lomentaria articulata

Osmundea pinnatifida







Rhodothamniella floridula

Mastocarpus stellatus

Palmaria palmata










Osmundea pinnatifida

Plocamium cartilagineum










Palmaria palmata

Saccorhiza polyschides










Plocamium cartilagineum













Rhodothamniella floridula




7 species

13 species

15 species

19 species

17 species


Characteristic species of macroalgal belts on Breton shores (including grouped Pc and Fspi) and their numbers per level

The complete list of characteristic species occurring in the intertidal zone on rocky shores in Brittany (and beyond, on the coasts of the Armorican Massif) comprises 33 genera / species of sea macrophytes, including 2 species of Lichens, 10 species of Phaeophyceae, 20 genera or species of Rhodophyceae and 1 species of Chlorophyceae. When additional names are indicated for a given taxon, they can refer to various shapes of the same species, to species which cannot be distinguished on the field (e.g. Laurencia obtusa / L. hybrida) or to common synonymes.





Ascophyllum nodosum

Asparagopsis armata / Falkenbergia rufolanosa

Bifurcaria bifurcata

Calliblepharis jubata

Catenella repens

Chondracanthus acicularis

Chondrus crispus

Cladophora rupestris

Corallina spp. pour C. elongata + C. officinalis + Haliptilon squamatum

Cryptopleura ramosa

Cystoclonium purpureum

Fucus serratus

Fucus spiralis

Fucus vesiculosus

Gelidium spinosum = G. pulchellum = G. latifolium

Gelidium pusillum

Hildenbrandia rubra = H. prototypus

Himanthalia elongata

Laminaria digitata

Laminaria saccharina

Laurencia obtusa ou L. hybrida

Lichina pygmaea

Lithophyllum incrustans

Lithothamnion lenormandii

Lomentaria articulata

Mastocarpus stellatus / Petrocelis cruenta

Osmundea pinnatifida = Laurencia pinnatifida

Palmaria palmata

Pelvetia canaliculata

Plumaria plumosa

Rhodothamniella floridula

Saccorhiza polyschides

Verrucaria maura


Complete list of characteristic macrophytic species on Breton rocky shores (extended to North of Biscay and West Channel) in the intertidal zone

(microhabitats such as ponds are excluded)

Index tables concerning the number of characteristic species per belt (or level).


characteristic species

value

Pc - Fspi

30

≥ 4

20

3

10

2

5

1

0

0



characteristic species

value

An - Fves

30

≥ 7

20

5 - 6

10

3 - 4

5

1 - 2

0

0



characteristic species

value

Fser

30

≥ 8

20

6 - 7

10

4 - 5

5

1 - 3

0

0



characteristic species

value

He - Bb

30

≥ 10

20

7 - 9

10

4 - 6

5

1 - 3

0

0



characteristic species

value

Ld

30

≥ 9

20

7 - 8

10

4 - 6

5

1 - 3

0

0


2.3. Cover by opportunist species
The sub-index takes into account the following taxa, whatever the level.
Phaeophyceae: Ectocarpales (Ectocarpaceae : Ectocarpus spp., Pylaiella spp., Hincksia spp.)

Chlorophyceae: Enteromorpha compressa



Enteromorpha ramulosa

Ulva spp.

Rhodophyceae: Ceramium spp.



Polysiphonia spp. (excluding both P. lanosa and P. elongata)

Boergeseniella spp.

Colonial microalgae Diatoms (either epiphytic or epilithic)

Values obtained per level are given in the table below. They are then summarized to reach a maximum score of 30, when covers of opportunists are < 5 % in each belt. When a belt is lacking, the total rating is obtained by adding the values of occurring belts and applying to the result a rule of three. In the calculation, the same weight is given to each belt (or group of belts for Pc + Fspi).


opportunist species per belt

value

cover

6

< 5 %

4

5 – 25 %

2

25 – 50 %

1

50 – 75 %

0

75 – 100 %

Index table for the cover of opportunist taxa per belt.
In the case of grouped Pc and Fspi, covers of a given taxon will be pooled and averaged (Pc + Fspi / 2).

2.4. Determining the qualitative status (boundaries)
The qualitative status of a given site for the EQ "intertidal seaweeds" is obtained by comparing the final mark with CFR boundaries previously established in Spain and at the EC level. The global index corresponds to the three sub-indexes calculated as above and added together: global plant covering (0 - 40), number of characteristic species (0 - 30) and cover by opportunist species (0 - 30).


boundaries

status

83 - 100

High

62 – 82

Good

41 – 61

Moderate

20 – 40

Poor

0 - 19

Bad


Annex
Field sheet WFD CW NEA Intertidal seaweeds

Site:


Date:

Samplers:


1. Global plant covering of the belts (covering percentages, ca. a few %)



Pelvetia canaliculata (Pc) :

Fucus spiralis (Fspi) :

Ascophyllum nodosum (An) / Fucus vesiculosus (Fves) :

Fucus serratus (Fser) / Rhodophyceae :

Himanthalia elongata (He) / Bifurcaria bifurcata (Bb) / Rhodophyceae :

Laminaria digitata / Laminariales (Ld) :
2. Surface of each bathymetric level (m2)

Pelvetia canaliculata (Pc) :

Fucus spiralis (Fspi) :

Ascophyllum nodosum (An) / Fucus vesiculosus (Fves) :

Fucus serratus (Fser) / Rhodophyceae :

Himanthalia elongata (He) / Bifurcaria bifurcata (Bb) / Rhodophyceae :

Laminaria digitata (Ld) :


3. Observations in the sampling squares

In each square, cover of all characteristic and opportunist species.

Covering percentages to be noted down by belt in each sampling square:

0 - 5 %, > 5 -25 %, > 25% - 50%, >50 % - 75 %, > 75 % - 100 %



Remember: three 33 cm X 33 cm squares per spot, taken hazardously at each sampling on the field, within three 1.65 m X 1.65 m permanent spots per belt, so within 9 squares and 0.9 m2 per belt and per year.






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