Methods

Seed collection

The study ran over two years and encompassed two separate flowering seasons. For the first year of study, reproductive shoots were collected from 5 locations within Lake Macquarie, a barrier estuary on the central coast of NSW, Australia (Fig. 1). The perimeter of the lake is dominated by seagrass, most notably Z. m uelleri. There are two (2) power stations that use the lake for cooling water and discharge the thermal effluent back into the lake at Myuna Bay (Eraring Power Station) and Mannering Park (Vales Point Power Station), resulting in temperatures approximately 2-3°C higher than ambient temperatures (Macreadie & Hardy, 2018; Suzzi et al., 2023). All sites for this study are within the southern half of the lake to avoid a heavy metal gradient (Roach, 2005) and extensive urbanisation in the north of the lake. In the second year of the study, two control estuaries situated near Lake Macquarie were included in the study, Brisbane Water and Tuggerah Lakes. At each of these estuaries reproductive shoots were collected at 3 locations.