Freshwater Wetlands – their importance to wildlife, the Biosphere, and why we need more of them
Article kindly supplied by Rob Gandola of the Herpetological Society of Ireland.
Freshwater wetlands, at their most basic, are any area where there is a permanent water body like a pond or lake, or a place in which the ground becomes so saturated from a source of fresh water that it is held at or near the surface over a prolonged timescale – usually weeks to months. If you think this means the term ‘freshwater wetland’ could be applied to a huge variety of habitats, both man-made and natural, you’d be right! The variety of freshwater wetlands is only surpassed by the variety of names we have for them – pond, swamp, mire, lake, bog, fen, flush, wet grassland, ditch, marsh, pool… the list goes on.
In terms of wildlife, freshwater wetlands hold the highest levels of biodiversity compared to any other habitat type and are the most at risk of disappearing. Why are they so diverse? The simple answer is that where there is water there is life. There is no secret recipe for increasing wildlife diversity in an area other than by providing a source of freshwater.
When it comes to the Dublin Bay Biosphere, we are exceptionally lucky. With freshwater wetlands found in all zones from orchid-filled dune slacks on North Bull Island in the Core, through amphibian and waterfowl friendly council-managed green spaces in the Buffer zone, to damsel and dragonfly rich ponds in the urbanised Transition zone. These wetlands are also made up of a selection of diverse ornamental and constructed wetlands, some of which are the remnants of old estates, 200 years old and contain rare species. These constructed features can also be of profound natural, historical, and cultural value. Variety aside, this does not mean that there are anywhere near enough wetlands nor does it mean that the existing ones are reaching their potential. We have a history of removing and in-filling these areas of importance. When it comes to wetlands, a little bit of love and appropriate management can go a long way to enhancing an environment for people and wildlife.
From a herpetological perspective (one that focuses on amphibians and reptiles) all three of our native species found in the Biosphere are associated with wetland habitats, and two are fully dependent on them for breeding (Common frog and Smooth newt). The Herpetological Society of Ireland has been monitoring, leading research, and conducting outreach on amphibians and lizard populations in conjunction with the three county councils that form the Biosphere partnership since before the Biosphere was expanded in 2015. While the monitored populations appear to be currently stable, these species will disappear if we don’t plan for the effects that climate change and population growth may have on these freshwater resources. Only through the creation of new wetlands and sympathetically managing existing ones can we ensure that these species not only persist but thrive, along with all the other wildlife that make up the food web in these environments.
In an ideal world, all managed public access green spaces would have at least one wetland feature, ideally more. Their installation could be linked to other existing on-site activities e.g. pitch and putt courses whereby the addition of new water hazards may create a more enjoyable experience! Installation of sustainable urban drainage features and water cleaning attenuation ponds to deal with run-off have been shown to be just as valuable for wildlife as they are for slowly releasing excess water back into the water table, this has the added benefit of alleviating the risk of flooding too. Wetlands by their very nature, have an extra inherent value in their profound ability to sequester excess carbon from the atmosphere, even greater than trees. So, let’s have more wetlands!
A note on garden ponds…
The importance of garden ponds is not to be understated. In some cases, garden ponds are the last refuge of species that have all but vanished from the surrounding area. In highly urbanised areas, garden ponds and other man-made water features can provide a stronghold from which recolonisation and reinvigoration of genetic stocks could take place, when the opportunities of new or remediated habitats become available. The installation of garden ponds where people have the means to do so should be encouraged. Small, simple wetlands such as these can have huge benefits for both wildlife and owner alike. They create habitat mosaics and wildlife corridors as well as countless hours of enjoyment.