Long-term monitoring in the biometrics of the red-swamp crayfish (Procambarus clarkii, Girard 1852) in Doñana Wetlands 2004-2022

Study Extent

The study area is located in southwest Spain in the Guadalquivir Basin and cover the Natural Area of Doñana (Natural Park with 538,35 km2 and National Park with 542,51 km2). The climate is Mediterranean sub-humid with Atlantic coast influence: wet mild winters and dry warm summers. The rainy period occurs between October and April, with a peak in December–January (yearly average precipitation is about 550 mm). Four main ecosystems are described in the area: the marsh, mobile dunes, Mediterranean shrubland with pine forests and a long beach of 30 kms.

Sampling

The monitoring of biometric parameters (total body length, cephalothorax length, cephalothorax width and weight) of red-swamp crayfish (Procambarus clarkii) in Doñana wetlands was initiated in 2004 as part of the Monitoring Program of Natural Resources and Processes. The aim was to obtain a temporal and continuous series of data in the biometry of the species to analyze the evolution in these variables. Data were recorded annually between 2004-2022 by more than 2 members of the monitoring team which performed samplings in different locations twice per year in winter-spring and summer seasons when the study sites are flooded.

Quality Control

The protocol used has been supervised by researchers and the data have been validated by the members who performed the sampling.

Method steps

1. The individuals were sampled at the 64 stations classified according to their location (on either aeolian sands or marshland). Modified commercial traps, similar to funnel traps, with 4 mm mesh size were used as sampling method, following the method by Bravo et. al., 1994. Between 5-9 traps were randomly distributed (until 50 cm of depth) in each location, depending of the flooded area and depth. The traps were left for 24 hours and emptied the content into white sorting pans. Individuals were counted and identified until the maximun taxonomic level in the field and realease.
2. Each individual captured was weigthed using an electronic balance within 0.2 g accuracy. Cephalothorax length (from the tip of the rostrum to the tip of the cephalatorax) and cephalothorax width (maximum width of the cephalothorax) were measured using a slide caliper within 0.1 mm accuracy. Total body length (from the tip of the rostrum to the tip of the telson) were recorded using a ruler within 0.5 mm accuracy. Data recorded during the surveys also included sex and maturation stage (inmature, mature) of the organisms when possible, as well as the time and georreferenced data of the capture. Between 2004-2007 data was registered in Excel file and since 2008 data was recorded in CyberTracker sequence.

1. Procambarus clarkii
   common name: Red-swamp crayfish rank: species

The study area covers the Doñana Wetlands on either aeolian sands or marshland.