Encouraging Biodiversity at Dublin Port

The area around Dublin Port is home to a variety of waterbirds and sea mammals, and forms a vital breeding ground for many of its feathered and furry inhabitants.

North Bull Island has been a designated Biosphere since 1981, UNESCO recognising its importance as a habitat for rare species of wildlife. Dublin Port Company understands the importance of the area around Dublin Bay and formed the Dublin Bay Biosphere Partnership in 2014, alongside the National Parks and Wildlife Service, Dublin City Council, Dun Laoghaire Rathdown County Council and Fingal County Council. The Dublin Bay Biosphere covers over 300 square kilometres, and key areas include the Tolka and Baldoyle Estuaries, Booterstown Marsh, Howth Head, North Bull Island, Dalkey Island and Ireland’s Eye.

No fewer than 20 Natura 2000 sites lie within a 15-kilometre radius of Dublin Port. These form part of the largest coordinated network of protected areas in the world, creating a network of core breeding and resting sites for rare and threatened species, and some rare natural habitat types which are protected in their own right. The aim of the Natura 2000 network is to ensure the long-term survival of Europe’s most valuable and threatened species and habitats, listed under both the Birds Directive and the Habitats Directive. Sites are designated as either Special Areas of Conservation (SACs) or as Special Protection Areas (SPAs).

Dublin Bay is designated as an SPA, based on the wintering waterbirds that it supports, particularly Light-bellied Brent Goose, Knot, Black-tailed Godwit and Bar-tailed Godwit. However, Dublin Bay supports nationally important numbers of a further 18 species.

BLACK GUILLEMOTS AND ARCTIC TERNS

One of the challenges around the port area in relation to bird species is the fact that some birds, like Common and Arctic Terns and Black Guillemots, breed in the environs of the Port. Indeed, the Black Guillemot frequently nests in holes and crevices in quay walls and other artificial structures in harbour areas, and can be found in large numbers between Poolbeg Lighthouse and Butt Bridge. Construction work on quay walls or other structures in the Port area has the potential to impact the Black Guillemot by removing potential nest sites.

Common Terns and Arctic Terns tend to nest in colonies on permanent structures and floating pontoons within Dublin Port. In fact, Terns have been known to breed in Dublin Port for over 70 years. No construction work taking place currently within the Port estate will have any direct impact on the Tern colonies, but dredging activity in the river channel and construction noise may potentially impact on the Terns nesting on fixed or floating structures within Dublin Port. Such activity could also impact on non-breeding waterbirds which feed on the mudflats and sandflats within the Port area at low tide, but studies have proved that birds will habituate to ambient construction noise levels below 70dB.

BIRDWATCH IRELAND PROGRAMME

Dublin Port Company has consistently supported BirdWatch Ireland in the monitoring and research of waterbirds within Dublin Bay via the Dublin Bay Birds Project, and DPC has recently committed to extend its support by a further three years.

The Dublin Bay Birds Project includes colour-ringing, radio-tracking and satellite-tracking of individual birds, which helps to assess certain locations within the bay for roosting and feeding, as well as seasonal variations and movement throughout the winter months both within the Dublin Bay area and across other estuaries along the coast.

Such close monitoring of the bird populations means that potential impacts of any Port activities can be predicted, assessed and addressed prior to any construction.

The Black Guillemot population is surveyed twice per year and has been since 2013, while the monitoring of Common Terns and Arctic Terns nesting within Dublin Port was carried out in 2021.

DPC has undertaken a number of measures to ensure these species are protected. Capital dredging projects, for example, only take place between October and March, when Terns are absent from Ireland. During periods of extreme low tide, DPC will suspend construction and operational activities so as not to disturb birds foraging and feeding on the mudflats and sandflats. For example, gates installed on the proposed Greenway will be closed during the period of greatest low spring tides to avoid disturbance at feeding grounds within the Tolka Estuary.

The Black Guillemot population within the Port is stable but lower than a decade ago. DPC has developed a conservation plan, including placing custom-made nest- boxes to help increase population levels. Some of these

MARINE MAMMALS

The waters of Dublin Bay are also home to a number of marine mammals, including cetaceans (whale, dolphin, porpoise) and seals, which are protected under national and international law.

The European Communities (Birds and Natural Habitats) Regulations 2011-2015 prohibit all forms of deliberate capture or killing of cetaceans in the wild, as well as banning the deliberate disturbance of those species, particularly during the period of breeding, rearing, hibernation, and migration, and the deterioration or destruction of their breeding sites or resting places.

Meanwhile, the number of Terns nesting on Pontoons provided by DPC has increased, with the majority of Dublin Port’s Tern population now nesting on these structures.

The results of the monthly bird counts during the most recent Winter Wetland Bird Monitoring Programme (2020/21) indicate that most numerous species were Pale- bellied Brent Goose, Oystercatcher, Dunlin, Redshank, Knot, Bar-tailed Godwit, Golden Plover, Black-headed Gull, Common Gull and Herring Gull.

The numbers of wintering waterbirds in the two SPAs surrounding Dublin Port have been maintained during the Alexandra Basin Redevelopment Project (ABR) and indeed many species have seen numbers increase.

Monitoring will continue as the MP2 and 3FM Projects continue over the coming years.

Dublin Bay, including the Port, is also home to Ireland’s two native seal species, the larger grey seal and smaller harbour or common seal. Indeed both species can be regularly seen ‘hauling out’ (resting after deep dives etc) on the rocks of Dalkey Island and the northern tip of Bull Island, and the waters around these ‘haul-out’ sites are a critical habitat for seals.

There are 26 cetacean species in Ireland, with the most common around Dublin Bay being the harbour porpoise, bottlenose dolphin and minke whale.

Three sites in Ireland have been designated to protect the harbour porpoise, including Rockabill to Dalkey Island SAC, which consistently records the highest densities of this species in North County Dublin. Dublin Port Company collected extensive visual and acoustic monitoring data during the ABR Project, the first major capital project in Masterplan 2040, which has provided valuable information in relation to the influence of seasonal, daily and tidal patterns on the behaviour and feeding rates of the harbour porpoise.

Bottlenose dolphins can be seen year-round, with increased sightings in the summer months, while minke whales have been spotted in north County Dublin from Howth Head to Lambay Island and on the Kish Bank.

MINIMISING UNDERWATER NOISE DURING CONSTRUCTION

The challenge for Dublin Port Company when it comes to marine mammals is to ensure that any major works, such as dredging, piling and drilling, do not create underwater noise that would impact the animals acoustically.

As part of the ABR Project, a Marine Mammal Mitigation Plan (MMMP) was prepared in consultation with Irish Whale and Dolphin Group (IWDG) Consulting, and a full-time Marine Mammal Ecologist (MME) is assigned to the ABR and MP2 Projects to ensure full MMMP implementation.

The full-time MME has carried out monthly seal surveys at North Bull Island since May 2016 and will continue until at least two years after construction activities related to Port development, providing data on any changes in numbers of both grey and harbour seals. Meanwhile, there is the potential to introduce a photo-ID technique for grey seals, who have a unique fur pattern on their necks which allows for individual identification; such a project would allow for more in-depth data on population numbers and seal movements.

DPC has also introduced a number of measures to ensure that marine mammals are protected from underwater noise, including a 1,000-metre exclusion zone for piling and a 500-metre exclusion zone for dredging.

At least one Irish Whale and Dolphin Group (IWDG) Marine Mammal Observer (MMO) carries out a pre-watch before any underwater noise activities commence in daylight hours in good visibility extending 1km or more beyond the limits of the assigned monitored zone and subsequently records data on noise activity and sightings, ensuring adherence to the NPWS Guidelines (2014).

UNDERWATER ACOUSTIC MONITORING SYSTEMS

DPC has deployed two real-time passive acoustic monitoring system (PAMs) in Dublin Bay at the approaches to Dublin Port, as well as two static acoustic monitoring systems (SAMs) at the dumping at sea site to the west of the Burford Bank and within Dublin Bay to provide information on the presence of marine mammals.

The PAM system provides information on the presence of marine mammals during periods when visual identification is constrained and it can provide large scale, real-time data on mammal movement. SAMs detect and log cetacean vocalisations, and are thus used to study feeding behaviours and will provide data on habitat use before, during and after project work by DPC. Data is analysed every three months, enabling any changes in activity to be identified and acted on.

Detection of marine mammal calls in real-time during dredging operations allowed immediate mitigation measures to be implemented to avoid any potential impact.

The implementation of the MMMP has ensured that no significant impacts on marine mammals have occurred due to any activities associated with the ABR Project in Dublin Port, Dublin Bay or the Rockabill to Dalkey Island SAC. IWDG Consulting, on behalf of DPC, will continue to monitor the marine mammals in the surrounding area of the Port to ensure DPC achieves its environmental objective of no impact on these species.

Indeed, the data collected on both bird and mammals during the coming years, as the Masterplan 2040 projects come to fruition, will increase knowledge and understanding of the ecology and behaviour of these creatures in Dublin Bay.

For more information on these or any of Dublin Port Company’s biodiversity projects, please contact Eamon McElroy, Port Engineer: emcelroy@dublinport.ie.