Neus Sanmartin
Researcher University of Barcelona
Prairie study in progress
Following the start of the project to monitor marine biodiversity in Special Conservation Areas (SCA), in 2021, the need arises to expand knowledge of the state of the different species and ecosystems that inhabit these areas, in order to be able to manage them appropriately.
In order to contribute to this objective, the meadows of the marine phanerogam Cymodocea nodosa within the ZEC of the Aiguamolls de l’Alt Empordà, in the Bay of Roses, have been studied, evaluating their ecological status.
C. nodosa meadows are of great importance for marine ecosystems as they are not only very productive places but also form a habitat where considerable biodiversity takes refuge.
The objective of this project is to make a first approximation to the ecological state of the C. nodosa grasslands within the ZEC of the Aiguamolls de l’Alt Empordà. This study seeks to deepen the knowledge of the area and provide data that will allow the monitoring of the grassland in the future. This study is led by the University of Barcelona, in collaboration with the CEAB-CSIC and the Alive Foundation and is part of the final degree project (TFG) of Inés Redondo.
(left) and distribution of sampled points (right)
Sampling in the Roses meadow was carried out during August 2024 and 4 points between 10 and 13.7 m depth were selected. The work was carried out with the Laica boat, from the Alive Foundation and 5 divers. At each point, five samples were taken using a 15 cm diameter metal core (Fig. 2) and 3 samples by hand for nutrient and metal analysis. Each collected sample was cleaned of sediment in a mesh bag and kept in a properly labeled plastic bag, in a portable cooler until arriving at the laboratory where it was frozen until processing.
The variables measured in the laboratory were:
Samples processed but not analyzed. Pending analyses are marked with an asterisk.
- Beam density (number of beams per m2)
- Biomass of leaves, rhizomes and roots (g of dry weight per m2). In the laboratory, the roots, rhizomes and leaves were separated, dried in an oven at 70o C for 48 h, and weighed.
- Root Weight Ratio: It indicates the ratio of root biomass to leaf biomass and is calculated as follows:
RWR=BA/(BF+BA), being: BA: Root biomass and BF: Leaf biomass - Bundle phenology (leaf weight, bundle biomass and number of leaves per bundle): It is measured from 10 bundles obtained with each of the samples collected at each point. The number of leaves of each bundle was noted and its dry weight (DS) was obtained in grDS bundle-1.
- Epiphyte load (g of epiphytes per gram of leaf). It was obtained from the 10 bundles used for phenology. Each of the leaves was deepiphyted by gently scratching its two sides with a slide. The two fractions were weighed separately (bundles and epiphytes) and the epiphyte load was obtained expressed in gPSepiphytes bundle-1.
- *Content and isotopic trace of nitrogen (%N and δ15N) in rhizomes.
- *Phosphorus content (%P) in rhizomes.
- *Content of copper (Cu), cadmium (Cd) and lead (Pb) in rhizomes…
For the data analysis (slopes), an analysis of variance will be used to see the differences between the different descriptors between the sampled points of the prairie and a principal component analysis (PCA) that will determine on the one hand, the importance or weight of each descriptor and on the other hand, the arrangement of the stations in a space composed of two axes, where the horizontal axis indicates the quality gradient.
