An introduction to Ireland’s biodiversity by Dr Don Cotton

In the global effort to protect the planet’s biodiversity it might seem that Ireland is an insignificant piece of land and marine continental shelf. However, we have a moral and legal responsibility to protect our biodiversity. As a developed nation we should also play a leadership role in this endeavour. Ireland does not support a particularly rich biological diversity due to its recent glacial history coupled with the geographical position. But there are some special habitats, and there are unique species and genetic variations within species in need of protection.

Ecosystem and habitat diversity

It is widely accepted by specialists working on diverse taxonomic groups that habitat and ecosystem protection is paramount to the conservation of species and genetic diversity. Describing the range of habitats is one of the most difficult yet important aspects of biodiversity. The publication of “A Guide to Habitats in Ireland” (Fossitt, 2000) was a great milestone, but the time is now right for it to be revised and extended. The involvement of people such as invertebrate ecologists and lichenologists is now needed to add descriptions of the micro-habitats that are crucial to the existence of their organisms. A modified system will make it easier for recorders to standardise habitat data that should accompany every biological record.

A wide range of surveys have been carried out in Ireland over the last few years which concentrated upon special habitats that are uncommon or rare in the rest of Europe. Several surveys are on-going but attention is now being given to sub-marine habitats which occupy ten times the area of the terrestrial environment. Reports from these surveys are mostly unpublished, they are often very long and detailed and are consequently not used as widely as they deserve. A review that summarises the main findings of these reports would be a most valuable publication.

Species diversity

Knowledge of which species are found in Ireland has depended upon there being people with expertise in the taxa. In common with other countries there is an imbalance in the state of our knowledge because organisms that are larger, more attractive and terrestrial, tend to be the best studied and have good identification works. For convenience one can divide our knowledge of species diversity in Ireland into three categories :

(a) Taxa that have regularly up-dated species lists and we know their geographical distributions and population trends

There are very few vascular plants waiting to be added to the Irish list that stands at just over 1000 native species with another 1075 ‘alien’species recorded. Not only that but we know their geographical distributions quite well and work is progressing on studies of sub-species and hybrids. A Red Data Book was published over 20 years ago but with all of the new information available an up-date version is now considered overdue. Vertebrates are also very thoroughly studied and it is generally possible to give an account of the distribution and ecology for about 550 species that includes all but the marine fish. There are organisations dedicated to specific groups within the vertebrates which has resulted in recent distribution maps, atlases and updated Red Lists. There are repeat distribution and abundance surveys in place for many of these groups of species some of which are reviewed on a cyclic basis.

It is notable that larger and more attractive invertebrates have also received special attention. The butterflies have been studied for many years but this interest has now spread to the macro-moths and is beginning to filter down to the micro-moths. This means that 1,454 species in Order Lepidoptera are receiving enough attention that distribution maps and patterns of abundance can now be discerned.

The 34 Irish species of dragonflies and damselflies (Order Odonata) have also had maps produced and habitat information has been gathered. The Mollusca have been a very collectable group for many years and consequently there are good species lists for marine littoral, terrestrial, and freshwater species. There are also atlases and on-going studies as well as published Red Lists for the molluscs. It is important to say that people studying all of the above taxa would point out that their group of organisms is still under-studied and there is so much more to do!

(b) Taxa for which there are species lists and a limited knowledge of their distribution, but little else

Organisms in this category generally have species lists and publications because they are championed by a small number of enthusiastic individuals, often by amateur naturalists and sometimes by just one person. Some of these groups contain thousands of species and this emphasises the difference between our knowledge of these organisms in comparison with the large, more appealing groups. During the last 10 years things have been moving quite quickly for some of these taxa, for example previously there were only species lists and vice county records for most of the lichens, bryophytes and spiders but due to intensive efforts these organisms are probably now well enough known to have Red Lists compiled.

(c) Taxa for which even basic species lists are lacking

In common with most other countries there are some taxa that have hardly been studied. The enormity of the task can be comprehended when the algal list stands at 1,054 documented species but there is an estimated 3,000 to 5,000 species; or the fungal list that stands at 5,500 species but there is an estimated 9,000 species. Invertebrate taxa are a huge mixture of unrelated groups of animals, many of which haven’t been studied in Ireland in recent times, if at all. This would be particularly true of marine animals and some soil organisms. For example, the tiny nematode worms could account for thousands of species.

Genetic diversity

Ireland, being geographically isolated, is a candidate for genetic drift and the evolution of unique subspecies and varieties. A few are already well known but undoubteldly more will be described in the future. Talk about genetic variety is regarded by some observers as premature when there are many groups for which basic lists of species don’t exist.

Invasive species

Ireland with its low species diversity and empty niches is particularly vulnerable to the arrival and the rapid, uncontrolled spread of invasive species. The collection and collation of data on such species is now routinely done and serves as an early warning system to try and prevent further invasions. There is also an issue around whether non-invasive alien species should be regarded as contributing to biodiversity.

Concluding remark

In any final analysis, it is important that the data collected is put to good use. Making lists and producing reports is just a first step but action is needed which results in the protection of habitats and species if Ireland’s biodiversity is to be conserved.

Photo credits: Liam Lysaght, Colette O’Flynn