Simultaneous harvesting by boaters at several points provides a unique opportunity to understand the distribution of plankton.
The study of coastal ecosystems requires observing the environment in the long term in order to detect possible changes in biodiversity, or even their functioning. However, the opportunity to sample at the several stations same time requires means at sea that scientists do not have.
Objectif Plancton, initiated by Océanopolis and with the participation of the Concarneau Marine Biology Station, the Institut Universitaire Européen de la Mer, the Lorient Plankton Observatory, Ifremer and the Explore Foundation is an original participatory science action carried out with the support of the actors of the maritime world (the associations Les Glénans, Cap vers la nature, ANSEL and Astrolabe Expédition). It offers the unique opportunity to sample plankton at different points simultaneously. This operation four times a year requires between 10 and 20 boats along the coasts of Brest, Concarneau and Lorient.
The protocol developed for this operation is simple with adapted equipment that allows boaters to implement it easily. During the day of sampling, participants are provided with kits containing:
- A Secchi disk (for measuring water turbidity),
- A tube for taking a water sample,
- A plankton net (phyto and / or zoo).
The crews, distributed at various points in Baie de la Forêt, carry out the sampling simultaneously. Back at the port, the samples are pre-analysed by scientists. The results of the previous operations are presented to the crews. The day ends by presenting the upcoming actions over a drink.
The Concarneau Marine Biology station is particularly interested in exploring the biodiversity of microalgae and ichthyoplankton (fish larvae), a speciality of researchers at the station, in order to make an inventory of the species present and to compare them with those previously described. As early as 1890, the station's researchers carried out the first surveys of the pelagic fauna and flora, thus transmitting us a reference system. Next, researchers focused on the impact of microalgae toxins on ichthyoplankton and the recruitment of juvenile fish.
Among the first results of this operation was the notable presence on the outing in June 2016 and by the most downstream stations of a micro-alga, Pronoctiluca pelagica, described for the first time in 1889 by Legendre during a sampling session carried out in Baie de la Forêt. The first outings highlighted the variation of plankton diversity according to the place and the season. Several micro-algae species known from hot to warm temperate waters were only recorded at the time of the outing in September 2016 and at the most downstream stations.
Finally, a knowledge base on ichthyoplankton is being developed. This base will allow computer-assisted identification of plankton and will be used by boaters.
The protocol developed in Concarneau is now active in other areas thanks to Astrolabe Expedition (Atlantic) and Exocéans (Côtes d'Armor).