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Christine Pergent-Martini & Ecosystem Team

(presented by Thibaut de Bettignies)

NATURA 2000 meeting – 13th -15th November 2018

Surface evaluation : a classical tool to detect spatio-

temporal evolution (e.g. Natura 2000 sites)

But needs :

- Availability of historical data

- Accuracy, reliability, reproducibility of these mapping data

Telesca et al. 2015

Corsica

� Several cartographic data (Total Nb 293)

Molinier, 1962

Coralligenous assemb.Detritic sand

Meadows

� Concerning long/mid-term periodThe first: 1962, 71 % since 2000 & 50% since

2010

� Existence of regional data concerning

Posidonia meadow all around the islandMeinesz et al. (1990)

Pasqualini (1997) 7 1st real map of Posidonia

Programme CARTHAMED 7 continuous map of benthic habitats with a

reliability percentage based on 12 criteria

(derived from MESH (2008)

Main benthic habitats & bottom types

> 90 %

> 80%

> 75%

> 70%

> 60%

< 50 %

% of reliability

Posidonia meadows

Meinesz et al, 1990

1

2

3

45

6

7

8

9

10

1112 13

14

Pasqualini, 1997

�Regression

17 % in 5 years

But in Meinesz potential habitat

effective habitat for Pasqualini

Pasqualini, 1997 CARTHAMED 2015

� Regression

11 % in 20 years

MEDAM

BUT*

No change in coastal management since 1995

Case study : Natura 2000 site

20112006

Upper limit of Paragan

34,8 ha 37,0 ha

With same methods 7Progression of 6 %

Natura 2000 site - Grand herbier de la Plaine orientale

Pasqualini, 1997 POSIDCORSE 2016

�Regression

10 % in 20 years

Diminution of % of interpolation

No data

Continuous

data

Presence of

anthropic damages &

natural

discontinuities

Test zone: Natura 2000 site - Grand herbier de la Plaine orientale

Biggest meadow of Posidonia in Corsica

Availability of :

� A continuous map of Posidonia meadows

� A complete coverage by acoustic data

� Aerial photographs & lidar images on shallow

bottoms

Anthropogenic activities & disturbances :

� Yachting and boaters

� Fishing (3 trawlers) � Commercial shipping

Goals :� Detect mechanical impacts

� Quantify them

� Assessment of their severity

Results :

Damages due to mooring of tankers (unloading terminal) and

commercial ships (mooring in case of meteorological disturbances;

visible on Lidar Data - SHOM)

More than 700 m long !

Marks of illegal trawling (double lines) inside

the meadow (visible on sonograms and in situ)

Results :

• 98 % of scars are between -20 and

-40 m depth

• Highest density is near the lower

limit of Posidonia (very sensitive

part)

• On the way of Bastia harbour

• More than 40 scars per grid unit in

the most impacted area

• Some scars are more than 2 km

long

12

Results :

Results :

Estimation of 280 ha of

Posidonia destroyed.

4% of the whole test

zone.

Around 150 years for a total

recovering of the meadow

50 years after 150 years afterState 0

Modelisation on a spatial analysis based on the

assumption of a linear recovery of 4 cm/year.

Regulatory measures with priority 1:

Limit anchoring in the posidonia meadow of recreational vessels

Anchorage outside Posidonia meadows ☐☐☐☐

Example of measures proposed in the DOCOB – Phase 2

Identify waiting areas for ships

concerned by meteorolgical contraints

���� Areas outside Posidonia meadows

Posidonia meadow

Previous waiting area

Present waiting area

On going

���� Done

Other measures envisaged

No renewal of the licence for trawling

Setting up mooring box for boats waiting for unloading Planned in 2019

���� No deadline

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