Substrates: Monitoring the recruitment rate of zebra mussels

Substrates are a method used to monitor the spread of zebra mussels across Lake Massawippi and its surrounding water bodies. The combined use of pyramidal and collector substrates provides an overview of zebra mussel propagation across the lake, and enables comparisons to be made between different areas. The local recruitment rate of zebra mussels can also be calculated.

A substrate with a zebra mussel recovered in autumn 2023.

Table 1. Summary of results for the pyramidal substrates project

Figure 1. Map showing the occupancy rate of pyramidal substrates on Lake Massawippi.

Table 2. Summary of results for the collector substrate project

  • These are devices made of 3 glass plates linked by a rod, immersed 2m below the surface in deep water, which act as a support for the veligers that cling to them. This is a robust detection method based on veliger development biology.

  • Il s’agit de dispositifs composés de soucoupes de jardinage liées par des tubes de PVC suspendus au bout des quais en eau peu profonde. Leur pouvoir de détection est plus modeste que celui des substrats pyramidaux, mais permet un déploiement à plus grande échelle. Les substrats collecteurs permettent aussi aux riverains de participer à un projet de science citoyenne.

  • Substrates allow us to establish a snapshot of zebra mussel presence across Lake Massawippi. In 2023, the substrates revealed the presence of zebra mussels in the northern two-thirds of the lake, whereas in 2024, zebra mussels were detected throughout the entire lake. It had been suggested that the significant water mixing caused by the July 2023 floods was at least partially responsible for the low colonization rates observed. The absence of such an environmental phenomenon in 2024 could explain the drastic increase in colonized substrates and the number of mussels found on them that year.

A substrate about to be hung on a quay in the early summer of 2023

Figure 2. Map showing the occupancy rate of collecting substrates on Lake Massawippi.