"Inter-callibration" Method

mercredi 3 juin 2015
par  Dorian GUILLEMAIN, Romain DAVID
popularité : 4%

Index of "Inter-calibration?"
1. Principle
2. Method
3. Sampling
4. Deliverables
5. To summarize
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How to cite this content :

David R., Arvanitidis C., Çinar M.E., Dubar J., Dubois S., Erga Z., Guillemain D., Sartoretto S., Thierry de Ville d’Avray L., Zuberer F., Chenuil A., Féral J.-P., (2014), with contributors : Açik Çinar S., Andral B., Aurelle D., Aysel V., Bakir K., Bellan G., Bellan-Santini D., Bouchoucha M., Celik C., Chatzigeorgiou G., Chatzinikolaou E., Chenesseau S., Dağli E., Dailianis T., Dimitriadis C., D’Iribarne C., Doğan A., Dounas C., Egea E., Elguerrabi W., Emery E., Evcen A., Faulwetter S., Gatti G., Gerovasileiou V., Güçver S.M., Issaris Y., Katağan T., Keklikoglou K., Kirkim F., Koçak F., Koutsoubas D., Marschal C., Önen M., Önen S., Öztürk B., Panayiotidis P., Pavloudi C., Pergent G., Pergent-Martini C., Poursanidis D., Ravel C., Reizopoulou S., Rocher C., Ruiton S., Sakher S., Salomidi M., Sarropoulou E., Selva M., Sini M., Sourbes L., Simboura N., Taşkin E., Vacelet J., Valavanis V., Vasileiadou A., Verlaque M. Protocols for monitoring of coralligenous habitats of mediterannean (Coralligenous based Indicators to Evaluate and Monitor the "good ecological status" of the MEDiterranean coastal waters) Protocoles de suivi du coralligène en méditerranée (Coralligenous
based Indicators to Evaluate and Monitor the "good ecological status" of the MEDiterranean coastal waters).

a. Inter-calibration on permanent transect?

[§ 1] Factors such as latitude, geomorphology and different environmental conditions produce a natural variability among coralligenous assemblages. Nevertheless, different observers and operators examining such natural variability by applying different methods and using different equipment, may introduce an additional variability that can mask the natural one. And this imply the achievement of discordant and, above all, non-comparable results. For this reason, a first phase of inter-calibration is envisaged.

[§ 2] Different photoquadrats will be shooted along a permanent transect in order to best reduce the natural variability of the assemblages, allowing the analysis of the variability due to methods, equipments, observers and operators. By this way, it will therefore be possible to “clean out” results in order to clearly separate and analyse the natural variability of the assemblages. This will allow better identifying which natural factors condition coralligenous assemblages all over the Mediterranea Sea, making, finally, possible a wide scale comparison.

b. Comparison of metrics variability between a permanent transect and random transects

[§ 3] The installation of permanent transect is not always possible, because it could bedifficult to set landmarks in the rock,and they can be quickly deteriorated (by divers, nets) or covered by sessile species, or simply beacause itmay not be allowed (e.g. in marine protected areas). Moreover, when studying the temporal variability, it is difficult to sample exactly the same locations as part of a large-scale protocol. Thus, it is best to identify some variables that are independent from the exact re-location of the study site?. Random sampling is more accessible to a wide variety of observers.

[§ 4] One of the preliminary objectives of this protocol will be to identify some robust variables, to be measured during the random sampling of coralligenous reefs. To do this, we will compare data obtained by the the permanenttransect to the ones obtained by sampling along transectsrandomly pleced underwater. The robustness of the variableswill be initially measured in Marseilles’ sites,testsin other areas will possibly follow.

c. Contextualisation? of the metrics measured along the random transects

[§ 5] Some variable can be very robust when all contexts are mixed up, but gain relevance and efficiency in a specific context. For example, the cartography allows us to study separately data from the image processing depending on the profile?. This approach allows to better understand the natural variability depending on the context (i.e. variability among sites).

[§ 6] Identify typical profiles of a context and analyse their simultaneity is the contextualization phase.Metrics from the analysis of photo-quadrats may also be elements of context for the molecular approach.

b. Operations

Depending on the ressources available for each partners, one main site will chosen for the inter-calibration of methods or observers on one hand, and as site of exercise at real depth on the other hand.

(Note : in Marseille, the main site is Frioul-Tiboulen du Frioul.)

Placing the marks for the permanent transect
Marks should be fixed in the rock : a threaded rod is sinked, then fixed with resin.. Three methods can be appliedcable. Here they are presented from easiest to the hardest :

- If an existing hole is present, clean it out from eventual encrusting species, then apply a resin in the hole and around the threaded rod and insert the rod inside (a hammer may be possibly necessary).

- Useof a chisel and a hammer to make the hole, then follow the same process as for method a).

- Use of a pneumatic immergeable drill (Rodcraft 4200 type), supplied with compressed air via a scuba tank and a diamond bit. Total air consumption is approximately 0.8 to 1 m3(a tank of 12 L at 200 bars contains 2,4 m3). It is possible to use a standard pressure regulator to sypply the drill, but this requires the adjustement of the pressure to 6 bars.

[§ 7] For this purpose, it would be interesting to acquire contextualization data on a large number of sites to better highlight the inter-site variability.
The study of natural variability observed on the two profiles chosen will be even more accurate if the surveys of context explain this variability.

PNG - 236.7 ko

Figure 1 : drilling of the wall with the Rodcraft drill gun (1) and use of a hammer (2)

[§ 8] On average, regardless of the method used, the placement of a rod takes about 10 min. Thus, in one dive it is possible to place 3 to 5 rods nearby.

PNG - 385.2 ko

Figure 2 : mark used as starting point for the permanent transects

[§ 9] A mark may be attached to the rod. It may be apparent, but avoid to use anything attracting for divers,which may take it home for their collection. A label can be used as a mark, but it should be cleaned regularly to prevent its covering up.
Note : the resin needs several hours to solidify (the warmer is the temperature, the quicker it solidifies).

[§ 10] Marking the permanent transect requires the following equipment :

  • For drilling :
    - Scraper
    - And/or chisel += hammer
    - Or drill « Rodcraft 4200 » type + its tank of compressed air + diamond drill bit
  • Threaded rods
  • Two-component polymerizing resin
PNG - 215.3 ko

Figure 3 : Rodcraft drill (1), drill connected to a tank of compressed air (2), diamonded drill bit (3)

Sampling will require :

  • 50 cm x 50 cm quadrat (Marseilles region) or other
  • Camera
  • Diving torch of sufficient quality to light up the area photographed and make colours visible and species identification possible
  • GPS? on the boat to locate the starting point

Image processing requires :

  • photoQuad software (open source)


- Deadline : 14th December 2015
- Please add comments for each paragraph (§) by means of a corrected new version (one form per §)
- It is recommended to add scientific references if necessary

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