Exploratory study on the optimisation of sampling effort in a non-vegetated lagoon within a Mediterranean wetland (Albufera Natural Park, Valencia, Spain)

Abstract

[EN] The analysis of macroinvertebrate communities is essential in aquatic ecology studies. Nonetheless, sample collection, processing and species determination of macroinvertebrates are extremely time-consuming and require huge efforts. Moreover, despite the crucial need for refined sampling protocols, investigations on viable benchmark sampling efforts are still scarce. This study provides a preliminary analysis on the optimisation of the sampling effort required to study macroinvertebrate communities from rice fields. Twenty core sediment samples were collected from a non-vegetated Mediterranean lagoon (rice field) in Valencia (Spain), and their macroinvertebrate community assemblages were obtained. Characterisations of the minimum number of samples needed for both faunistic inventories and environmental quality assessments were carried out using diversity indexes (number of taxa, Shannon, Simpson, and Margalef indexes), ecological indicators (Nutritional Mode Index, IMN) and several species richness estimators (Chao 1, Chao 2, Jacknife 1, Jacknife 2, ACE, ICE, Bootstrap and EstimateS 9.1.0). Our results indicate that in surveys in which the taxa richness of the communities is the objective, 20 samples or even more could be needed. However, when the objective of the study is to assess the environmental quality by means of ecological indexes such as the IMN, three samples could be an acceptable benchmark. Our findings, despite being limited by our experiment conditions, can provide methodological guidelines for ecological assessments in Mediterranean rice fields and shallow non-vegetated lagoons. Further research involving multiple study areas and seasonal patterns will help meliorate the accuracy of this protocol and refine sampling efforts in wetlands.