Solent Seagrass Project
Seagrasses are unique in that they are the only group of flowering plants in the world able to live fully immersed in sea water. They favour shallow coastal areas and are found on sandy and muddy sea beds. Seagrasses may be uncovered at low tide or permanently submerged but they never grow deeper than a few metres underwater because they need a lot of sunlight for growth. Unlike algae which evolved in the sea, seagrasses have evolved from land plants which have colonised the margins of the oceans. They are highly evolved and can complete their lifecycle underwater - they even have waterproof pollen!
Though nationally scarce and vulnerable, seagrass occurs in several locations around Hampshire and the Isle of Wight. We have two main species - dwarf eelgrass (Zostera noltii) and common eelgrass (Zostera marina), but there are also small stands of tasselweed (Ruppia sp.).
Why are they so important?
Seagrass meadows have long been recognised as an important habitat for marine wildlife. Underwater, the dense cover of leaves acts as a nursery for juvenile fish and crustaceans, like shrimps and crabs, and provides shelter from strong currents and predators. Due to their importance as a habitat and nursery ground for many species seagrass meadows are classified as Biodiversity Action Plan habitat. Seahorses favour these areas and anchor to the plants using their tails. These elusive creatures, although rare, are believed to live in meadows around the Isle of Wight.
As well as providing havens for certain species, seagrass is food for birds like brent geese, teal and swans especially when it is exposed at low tide. Its dense network of roots and rhizomes acts to bind the sediment together making the sand or mud more stable and slowing down coastal erosion. Seagrass is also capable of storing carbon, like land plants, and can hold the same amoun of carbon per hectare of meadow as the world's forests. This is a great natural sink for carbon dioxide, one of the major greenhouse gases.
The Solent Seagrass Project
We have been studying seagrass around the coasts of Hampshire and the Isle of Wight to learn more about its distribution and the health of our local populations. Staff and volunteers from the Trust have been visiting local seagrass sites and conducting annual surveys. The project involves many partnership organisations who have contributed historical data or assisted on recent surveys. Project partners include Inshore Fisheries and Conservation Authority (IFCA), Southampton National Oceanographic Centre, Environment Agency, The Isle of Wight Council and Seasearch divers.
We have gathered historical records of seagrass around our counties from numerous sources and added it to our own data to compile an inventory of seagrass for the Hampshire and Isle of Wight area. By learning about where seagrass exists now and where it is no longer present we are better able to understand and protect it.
Our 'Inventory of Eelgrass Beds in Hampshire and the Isle of Wight' includes a report section and a data section and is updated annually to incorporate new data. The report details the biology and ecology of Zostera (seagrass), current threats, conservation and management options, and survey and monitoring techniques is available to download here. The data section comprising of site maps and inventory forms is available by request.
Seagrass Reporting Form
We would like people to let us know when they find seagrass on the shore or underwater. This information could help to identify previously unrecorded seagrass meadows and allow us to champion the conservation of these wonderful but often under-appreciated habitats.
Request a copy of our latest Inventory of Eelgrass Beds in Hampshire and the Isle of Wight by emailing Amy Dale on AmyD@hwt.org.uk (the report section is available for download above).
Download a podcast about seagrass.
The Yarmouth Harbour Commission requested a detailed survey of the seagrass bed located in Yarmouth, Isle of Wight in 2008. A copy of the resulting report can be downloaded here.