Data from CoFish: co-designing citizen science between fishers and scientists to monitor the phosphorus distribution across two Lake Geneva basins

Background
Eutrophication, followed by re-oligotrophication during lake restoration, in many peri-alpine lakes has caused important changes to the functioning and biodiversity of freshwater ecosystems. In Lake Geneva, total phosphorus (TP) concentration has been reduced since the eutrophic years, and is now close to the upper value of the target range of 10-15 µg/L. For over 60 years the lake has been monitored at SHL2, the central and deepest point in the Eastern basin, complemented by data from GE3 in the Western basin. Selection of these reference points was based on a lake-wide analysis of TP in the 1950s. Fishers have for some time expressed concerns that further reductions in TP could damage the sustainability of their livelihoods. They have called for a re-evaluation of the historical sampling points to determine whether SHL2 and GE3 can still be considered representative in terms of nutrient concentration of the lake.
Results
Here, we present the scientific and societal impacts ..., Sample collection
The data were collected by citizen scientists. To collect samples, we constructed an 18m long integrated water sampler out of a garden house, fitted with a cork stopper at one end and a 5kg weight at the other following a design used in the European Multi Lake  Survey protocol (Mantzouki et al., 2018). While not the central objective of the study, we also measured lake transparency and trained fishers to use Secchi disks. Average Secchi depths were calculated as the mean of the depth at which the Secchi disk was no longer visible and the depth that it starts to be visible again, once bringing it up to the surface.
Lab analyses
Samples were analyzed for TP and P-PO4 using a Seal Analytical AQ2, following protocols EPA 119-A-Rev. 7 and EPA 155-A, which is based on a reaction of acidic molybdate in the presence of antimony. The limits of quantification were 3μg/L for both with a range of 3-100 μg/L for TP and 3-300μg/L for P-PO4. Methods were chosen to correspond to..., , # Data from CoFish: co-designing citizen science between fishers and scientists to monitor phosphorus distribution across Lake Geneva

[https://doi.org/10.5061/dryad.73n5tb379](https://doi.org/10.5061/dryad.73n5tb379)

## Description of the data and file structure

**Dataset** contains data for sampling coordinates, fisher ID, sampling campaign, date, time of collection, Secchi 1= depth at which the disk disappears, Secchi 2= depth at which it re-appears when lifting it out of the water, Secchi_avg= the averages of Secchi1 and Secchi2. Units are in m.

**meanP-PO4_GVA=** the average based on three replicates (units in g/L),

**sdophos_GVA_** the standard deviation for that measurements

**TotalP_AuA_ugL=** Total P (units in g/L)

### Files and variables

#### File: all\_data\_CoP\_dryad.csv

##### Variables

* Campaign: sampling campaign
* Date: date of sampling
* Sample name: unique code based on CIPEL naming
* Site: unique site name
* Lake basin: Grand/Petit
* Location: Transect
* L...,