The Solway Firth is an estuary in the South West of Scotland and the North West of England, opening into the Irish Sea with the Isle of Man located beyond the Solway Firth but lying in the trajectory of the South West direction of the Firth. A wide variety of marine and coastal habitats and species can be found in the Firth, contributing to the overall biodiversity of Scotland and England while sharing one Solway Firth ecosystem.
The seabed is variable with sandy, highly mobile sediment located in the inner Solway, with sandflats and mudflats offering ideal habitat for invertebrates, crustaceans and molluscs, and important habitat for birds, especially waders and waterfowl. Crabs, worms, shellfish, natterjack toads, nursery grounds for skates and rays, and nursery grounds for fish such as smelt and bass are just some of the important features and biodiversity found in the inner Solway.
The Firth is one of the largest estuaries in the UK, and has the second largest tidal range in the UK, after the Severn Estuary. This creates a large intertidal zone, which is covered with water at high tide but exposed at low tide. The Solway has extensive areas of saltmarsh habitat, which is increasingly shown to be valuable as a blue carbon store as research on the subject grows. See more about intertidal rocks, sediments and biodiversity in the Solway here. Wetlands are found throughout the Solway, with two Ramsar designations for wetlands of international importance found here.
Saltmarsh and sand dunes of the inner Solway are home to the Natterjack toad, Epidalea calamita. This is a rare and threatened species, and the UK’s loudest amphibian, which can be found on both sides of the Solway in the most northerly part of its range. The Solway is the only area where natterjack toads can be found in Scotland. Only a handful of sites where natterjack toads can be found remain in the UK, with 75% of breeding sites for this amphibian having been lost over the last 100 years (Amphibian and Reptile Conservation, n.d.). Known sites for natterjack toads include the Solway Coast Area of Outstanding Natural Beauty, Caerlaverock National Nature Reserve, WWT Caerlaverock Wetland Centre, and more. Natterjack toads were once found all along the English Solway Coast, and along the Scottish coast out passed Southerness, however their range has since reduced. They breed in shallow ponds, and so new ponds have been created in conservation efforts at the Royal Society for the Protection of Birds (RSPB) Mersehead site, and the Solway Coast Area of Outstanding Beauty Mawbray Banks in recent years. The conservation efforts at RSPB Mersehead in recent years saw numbers of breeding natterjack toads increase by 400% over the three year project, from 30 to 150 breeding males (Royal Society for the Protection of Birds, 2017). The Scottish population, however, has been in decline in recent years. Conservation work regarding natterjack toads is ongoing with the Amphibian and Reptile Conservation Trust leading on ‘Coastal Treasures’ focussed on the Scottish Solway natterjack toads. Coastal Treasures is part of the ‘Species on the Edge’ which is creating a programme of conservation work in partnership with 7 other organisations, and hopes to implement the work thereafter. To read more about the Coastal Treasures project click here.
The North Atlantic Drift (northern extension of the Gulf Stream) in addition to the shallow nature of the Firth provides warmer waters, and air. This warmer influence is the reason Logan Botanic Gardens is located within Galloway, on the west coast of the Rhins. The warmth of the Gulf Stream provides a mild climate for the gardens allowing the botanic gardens to grow exotic species of plants.
Marine fish and shellfish thrive in the Solway, with fisheries and processing sectors relying on shellfish caught in the Firth. Tropical species of fish have even been recorded in the Solway, such as swordfish, Xiphias gladius, the sunfish, Mola mola, a number of tunnys, sharks and some seahorses have even been recorded in the Solway.
Designations ranging from internationally important world-spanning networked designations, to local conservation measures are in place within the Firth to protect and conserve the species and habitats known to be endangered, at risk, or important on a regional, national, and international level.
The majority of the English side of the Solway Firth, down to Whitehaven, is now covered by the recently extended and renamed Solway Firth Special Protection Area. This area supports species of European importance including; Red-throated diver (Gavia stellata); Whooper swan (Cygnus cygnus); Barnacle goose (Branta leucopsis); Golden plover (Pluvialis apricaria), and Bar-tailed godwit (Limosa lapponica). It also supports migratory populations of 23 species of European importance. The RSPB has several reserves around the Solway Firth, covering areas of the inner Solway including Campfield Marsh (England), Mersehead, and Kirkconnell Merse (Scotland). There are also RSBP sites on each of the cliffs at either side of the mouth of the Solway Firth at St Bees Head (England) and Mull of Galloway (Scotland). See more about Solway protected areas here.
Although seals are less common than in other parts of the UK, both the Atlantic grey seal, Halichoerus grypus and the harbour (common) seal, Phoca vitulina are both present in the Solway Firth. Elasmobrachs (sharks, skates and rays) and cetaceans (whales, dolphins and porpoises) are also present in the Firth. All of these species are under growing pressure from human activities and impacts such as; underwater noise, collision with vessels, and marine litter.
Like all other marine ecosystems, all of the Solway’s environmental features are under pressure from a range of human induced (anthropogenic) issues. Marine litter and underwater noise, as already mentioned, pose new and growing risks, along with climate change. Climate change can cause many primary and secondary negative impacts on the marine environment. This can add pressure to; marine fish and shellfish and other species, birds, coastal, intertidal, shallow and shelf habitats, and socio-economic sectors through ocean acidification, sea temperature rise, sea level rise, flooding, waves/storms, salinity and more changes. Climate change may also increase the spread and establishment of marine invasive non-native species. Some marine invasive non-native species are already present in the Firth and they have the potential to cause environmental and socio-economic harm to the area. Some anthropogenic pressures on the marine environment are more limited in the Solway than in other parts of the UK. This is because the Solway coast is not densely populated, with people living in small villages and towns rather than bigger towns and cities. The Solway has no activity related to the UK’s oil and gas industry, has limited vessel traffic, and is not heavily industrialised.
Image; Natterjack toad. © Solway Coast Area of Outstanding Natural Beauty.