Development of a biological early warning system based on the reactions of the bivalve mollusc Pecten jacobeaeus (Linnaeus, 1758) to unfavourable conditions

Bivalve molluscs (Bivalvia) are a group of invertebrates that can be found in freshwater and saltwater habitats. Due to their filter-feeding and sessile lifestyle, bivalve molluscs have been the subject of numerous studies to monitor their response to environmental changes, thereby developing potential early warning systems for aquatic pollution based on living organisms. Such systems often record the closing of bivalve mollusc shells as an indicator of the molluscs' reaction to changing environmental conditions. This study analysed the possibility of using the bivalve mollusc Pecten jacobaeus (Linnaeus, 1758) in a pilot early warning system. Four experiments were conducted on six specimens to study the reactions of P. jacobeus specimens to the presence of selected substances in the environment. Three specimens were assigned to both the experimental and control groups. In the first experiment, the reactions of the shellfish to gradually reduced salinity for twenty minutes were monitored. In the second experiment, the responses of the shellfish to an increase in the amount of alcohol in seawater for fifteen minutes were observed. In the third experiment, the reaction of the scallops to the addition of microplastics was monitored for twenty minutes. In the fourth, the responses to the addition of sunflower oil to seawater were monitored. A custom system utilising Hall sensors and an Arduino microcontroller was developed to monitor the opening and closing of the shells. The system registered each closing of the shells on a personal computer. The experiments recorded the reaction of the shellfish to a decrease in salinity and the presence of alcohol, which was manifested by the closure of the shells. No response to microplastics and oil was recorded in the experiments. This pilot study has demonstrated the potential of using the closure of scallop shells as an indicator of environmental changes.