New insights on bioindicator value of Chironomids by using occupancy modelling

CORTELEZZI AGUSTINA; SIMOY MARÍA VERÓNICA; SIRI AUGUSTO; DONATO MARIANO; CEPEDA ROSANA; MARINELLI CLAUDIA; BERKUNSKI IGOR

ECOLOGICAL INDICATORS

ELSEVIER SCIENCE BV

Año: 2020 vol. 117

1470-160X

The aim of this work was assessing the association of chironomids to several water quality variables in lowlands streams. While chironomids are used worldwide as bioindicators, how its occupancy varies along the gradient of these physic and chemical variables remains unknown. We used multivariate analysis and occupancy modelling to understand the relationship between abundance and occupancy of the chironomid taxa and the water quality variables. We described the sensitivity of each taxa by using occupancy modelling. We determined the association between 21 taxa of the chironomid assemblage and five variables of water quality (i.e., conductivity, dissolved oxygen, 5-days biochemical oxygen demand, concentrations of phosphate and dissolved inorganic nitrogen). Conductivity, dissolved oxygen, and concentrations of phosphate and dissolved inorganic nitrogen were associated to the abundance of chironomids. We identified taxa associated to low water quality (e.g., Chironomus calligraphus) and high-water quality (e.g., Rheotanytarsus). In some chironomid taxa their potential as bioindicator increased as the taxonomic level decreased (e.g. Chironominae). However, in other taxa this potential as bioindicator of water quality remains at subfamily level (e.g. Orthocladiinae). The occupancy of Parachironomus sp. and Chironomus calligraphus increased in the sites with the lowest concentration of dissolved oxygen, while Rheotanytarsus sp. and Onconeura analiae behaved in an inverse way. Chironomus calligraphus and Onconeura analiae occupied sites with high values of both, conductivity and 5-days BOD. Chironomus calligraphus was the single species showing a positive relationship between its occupancy and concentration of phosphate. The occupancy of Allocladius neobilobulatus and Cricotopus sp. were negatively related to the increase of the concentration of nutrients. The description of species sensitivity in terms of occupancy, offers a new methodology to understand how the species behave along a stressor gradient. Further studies about sensitive of local chironomid species to different types of stressors will allow researchers to generate more accurate biotic indices based on this taxa. The water quality of lowland streams would be inferred from the occupancy of chironomid taxa.