Episodes of critical salinity values in the estuary of the river Ulla (Galicia, Spain) in the hydrological years 1961 to 2022

The dataset includes the number of critical salinity episodes, as a function of salinity thresholds and their duration, that could have caused mortality events of different intensity of bivalves of commercial interest in the Ulla river estuary (Galicia, Spain) for hydrological years 1962 to 2022. 

A hydrological year is defined as the one starting in October and ending in September of the following year. The series includes four of the possible critical episodes defined by Parada et al., 2012 (DOI: 10.1007/s12237-011-9426-2): Salinity (S) below 10 for 1 day (S10-1d); S<30 for 18 consecutive days (S30-18d); S<5 for 1 day or more (S5-1d) and S<30 for 19 consecutive days or more (S30-19d). The first two types of events can cause moderate mortalities of commercial bivalve molluscs and the second severe mortalities (Parada et al., 2012; DOI: 10.1007/s12237-011-9426-2). Moderate mortalities are defined as events where mortalities of less than 50% of the cockle (Cerastodema edule, L. 1758) and up to 15% of the clams Ruditapes decussatus (L., 1758) and R. philippinarum (A. Adams & Reeve, 1850) are recorded in the estuary. Severe mortalities are defined as events in which mortalities of 50% or more of the population of C. edule and the clam Venerupis corrugata (Gmelin, 1791), and 15% or more of R. decussatus and R. phillipinarum are recorded (Parada et al., 2012; DOI: 10.1007/s12237-011-9426-2). The file is composed of 5 columns: the first column contains the hydrological year and the following columns contain the number of episodes recorded for each of the four categories (S10-1d, S30-18d, S5-1d and S30-19d).