Determinants of macrophyte palatability to the pond snail Lymnaea stagnalis

Summary 1. This study aimed to identify the chemical and structural determinants of macrophyte palatability to the pond snail Lymnaea stagnalis. Eleven macrophyte species were investigated, and one of them (Potamogeton lucens) was collected at four sites, on two different dates in the year, to study palatability determinants at an intra-specific level.

2. Plant palatability to L. stagnalis was determined through non-choice feeding assays. Dry matter content (DMC), total phenolic content and protein content were measured for each macrophyte species. These parameters, and soluble carbohydrate content, were also measured for each sample of P. lucens.

3. The palatability of macrophytes was positively related to their protein content (between species only) and negatively related to their DMC (both between species and within P. lucens). No simple relationship was found between the palatability of macrophytes and their phenolic content, but highly palatable macrophytes consistently exhibited a low phenolic content.

4. These results emphasise that macrophyte palatability is a multifactorial attribute, potentially depending on both structural and chemical traits. Because some of these traits were correlated, further investigations are required to assess their respective influence on macrophyte palatability.