In July 2021 a new cycle of monitoring the subtidal seagrass Zostera marina beds in Studland Bay Marine Conservation Zone (MCZ), in Dorset, commenced. The site was previously surveyed in 2018 by the Environment Agency to record the seagrass extent and percent cover. Natural England led the 2021 survey programme following the methods developed for surveying seagrass beds in Torbay. The data collected will allow the condition of the subtidal seagrass beds to be assessed against some of the targets for this feature of the MCZ.
The survey programme (including the EA 2018 survey) was designed primarily to monitor the following attributes of the subtidal seagrass bed: extent and distribution, structure and function. It also aimed to provide data to support the assessment of the spiny (long-snouted) seahorse attributes: quality and quantity of the habitat available, population size and age / sex ratios.
The data collected in 2018 and 2021 provide the first step toward recording statistically robust and repeatable monitoring data against which future data can be compared.
The key findings were:
- Monitoring sites were selected based on the EA 2018 survey data of bed extent and percentage coverage, where seagrass occurred in the bay percentage cover values ranged from 24-81%.
- Seagrass wasting disease, Labyrinthula sp. was observed across the sites monitored.
- Non-native species were recorded throughout the bay and were mostly observed to be in low abundance. The exception was the tetrasporophyte pase of harpoon weed, Asparagopsis armata, which occurred in high numbers in some areas.