Water ecological requirements of Characeae taxa in eastern Spain

Presence of Characeae taxa is limited by the existence of clear and oligotrophic waters. Some other chemical water parameters can also influence the distribution of taxa, which can thus be used as ecological bioindicators. The area of eastern Spain contains a high diversity of water basins in both coastal and inland habitats that allow the study of ecological gradients. This work aimed to identify the most relevant and significant water chemical parameters that determine the distribution of Characeae taxa, and establish their optima and tolerance ranges for each parameter in eastern Spain. Ninety-six records corresponding to unpublished old and recent samplings of the presence of 17 taxa belonging to the genera Chara, Nitella, Tolypella and Lamprothamnium were related to water parameters that included salinity, pH, electric conductivity, total water hardness, alkalinity, concentrations of Na+, Mg2+, Ca2+, Cl-, and SO42-, and Mg2+/Ca2+ ratio. Principal Component Analysis showed that salinity was the major factor that determined the distribution of Characeae taxa, followed by concentration of Mg2+, Mg2+/Ca2+ ratio and alkalinity. When previously published records from the same area were added, non-parametric tests showed significant differences among taxa only for salinity, water hardness, and Mg2+/Ca2+ ratio. These statistical analyses, along with optima and tolerance ranges for each parameter showed that Characeae taxa, especially Lamprothamnium papulosum and Tolypella spp., could be used as bioindicators in eastern Spain, although their ecological differentiation is not clear in many cases.