Enterprise Energy Ireland Ltd Corrib Offshore EIS

7. FLORA AND FAUNA

7.1 Introduction

An assessment has been made of the offshore and coastal areas of the proposed Corrib Field and pipeline route (to the high water mark), in terms of the likely impact on the habitats present, together with constituent flora and fauna species. Information provided is based on a review of the existing literature, consultation with a number of conservation organisations, and fieldwork in the Corrib Field and along the pipeline route. The offshore fieldwork was undertaken by Gardline and Aqua-Fact Ltd in 2000, and by EcoServe in 2001.

The Corrib Field is located some 65 km west of County Mayo (see Figure 1.1) in approximately 350 m water depth. The proposed pipeline route runs east from the Field through Broadhaven and Sruwaddacon Bay to the proposed Terminal site at Bellanaboy Bridge. This section has been divided into offshore (defined as the waters outside Broadhaven Bay), nearshore (defined as coastal areas and waters within Broadhaven Bay) and the landfall area, including Sruwaddacon Bay (which is crossed twice by the pipeline). The pipeline and umbilical routes are described as one, except where the pipeline and umbilical are being referred to specifically.

Maps contained in this section cover the offshore section of the pipeline route. The onshore section of the pipeline between the landfall and the Terminal is described in Section 19.

7.2 Study Methods

The aim of the literature review, consultation exercises and surveys was to:

• identify habitats or species on, or close to, the proposed Field and pipeline route, which are likely to be of commercial or scientific interest and/or conservation value; and

• investigate the presence of protected species of flora or fauna.

These findings have been used to identify mitigating measures to reduce the impacts during construction and operation.

The methods and objectives of the Corrib Field and offshore pipeline route surveys were discussed and agreed with the Petroleum Affairs Division (PAD) of the Department of the Marine and Natural Resources (DOMNR).

7.2.1 Literature Review and Consultation

Information was obtained from the following sources:

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• benthic communities: baseline surveys carried out in the general area of the Corrib Field and pipeline route, and existing marine biological survey data;

• fisheries: ICES fisheries data, Irish catch data, the Central Fisheries Board and from Jee Associates (2000);

• plankton: published sources;

• seabirds: surveys conducted by the Cetacean and Seabirds at Sea teams of the Coastal Research Centre at University College Cork (CRC), on behalf of the Rockall Studies Group (RSG) and the Porcupine Studies Group (PSG) (Petroleum Infrastructure Programmes II and III), counts of wintering wildfowl and waders in the Sruwaddacon by Dúchas; and

• cetaceans: stranding data recorded in the Irish Naturalists' Journal, sighting data supplied by the Irish Whale and Dolphin Group, survey carried out by CRC, a survey carried out by Gordon et al. in 1993 (Gordon et al., 2000), data collated by Berrow (2000), and two papers published by Clark and Charif (1998 and 2000).

7.2.2 Baseline Marine Studies and Surveys

7.2.2.1 Offshore and Nearshore Area

Enterprise commissioned physico-chemical and macrofaunal sampling, and a seabed video and photograph survey in the vicinity of the Corrib Field and along the proposed pipeline route. The details of these surveys are provided below:

Macrofaunal grab samples were taken from 27 sites within the Corrib Field during summer 2000. The locations of these sites within the Field are shown on Figure 7.1. A further 12 stations were sampled along the pipeline route between the Field and the landfall, their locations are shown in Figure 7.2. The samples were sieved over a 1 mm mesh.

The surveys were designed to identify any changes in fauna in the Corrib Field which could be attributable to historic drilling activities, and to establish the main changes in benthic communities with depth along the pipeline route. Some of the stations sampled will also be useful as future baseline reference points, as they were outwith any potential impacts from drilling and pipelay operations.

In most cases three replicate grab samples were obtained from each of the Corrib Field sites, however there were some sites where only two were retrieved. Two replicates were analysed from each of the pipeline route stations.

In order to have comparable data on density of individual organisms for the Corrib Field sampling locations, the numbers were multiplied up to give a number of individuals that would be found in 0.5 m2 (for example, where 3 samples were taken the total was multiplied by 1.66, and where only 2 were

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taken the total was multiplied by 2.5). A further sample from each site was taken for physico-chemical analysis (the physico-chemical results are presented in Section 8). The sampling was carried out using a 0.1 m2 Day grab, which is standard equipment for this type of survey.

6029000

6028000 REF1 6024400

C1

6027000 6024200 C2

18/20-3 6026000

6024000 C3

6025000

F7 C4 6023800

18/20-1 Z1 18/20-3 Northing 6024000 F1 F2 367400 367600 367800

Z2 F8 18/20-2z F6 6023000 18/20-4 REF2

Z7 F4 F3 6023500 6022000 Z8 Z3

Z4 18/20-2z

Z12 Z11 Z10 Z9 F9 18/20-4 6021000 18/25-1 Z5 F5 6023000

Z6

366000 366500 6020000 363000 364000 365000 366000 367000 368000 369000 370000 371000 372000 Easting

Key

Existing Physico-chemical 18/20-4 Well & invertebrate sample location

Figure 7.1: Benthic sampling locations in the Corrib Field

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6030000 REF1

41A 38A 36 35 17 12 33A 10 REF2 32A 18 6025000 30A 21 20 28 27 15 15A 26

25C 6020000 25B 8 25A

Northing 6016000 6015000 25 JN336 6015500 STN 1 T1 HS T1 LS T1 MS JN336 JN336 JN336 T6 MS STN 4 STN 3 STN 2 6010000 6015000 444000 445000 446000 447000

365000 370000 375000 380000 385000 390000 395000 400000 405000 410000 415000 420000 425000 430000 435000 440000 445000 450000 Easting

Key

Existing Sealine Coastline Physico-chemical Invertebrate Location Well 18/20-2z Route Location

Figure 7.2: Benthic sampling stations along the proposed pipeline route

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In addition to the intrusive sampling, sediment photography was also undertaken. The sediment surface was photographed at all sites, and at several sites in the Corrib Field, sediment profile imagery (SPI) was also undertaken. SPI photographs show a vertical profile of the sediment, taken by equipment which penetrates a few inches below the sediment surface. Corrib Field photos (including SPI) are provided in Figure 7.3, along with the numbers of species found at each site. Pipeline route photos are provided in Figure 7.4, along with the numbers of species found at these sites (Figures 7.3 and 7.4 are provided in plastic folders at the back of this chapter).

The aim of the surface photography was to provide a record of the fauna and flora which is present on the seabed, but not easily sampled using the Day grab. In addition to the stills photography, video of the seabed along the proposed route was taken at a number of places. The objective of this videography was to determine whether or not cold-water corals (e.g. Lophelia pertusa) were present. Lophelia tends to grow in deep water on hard substrates. The Corrib pipeline route has been designed to avoid rocky areas. However, historic ‘ice-berg’ scour marks do exist on the seabed close to the Corrib Field, and it was considered possible that the consolidated sediment at the edges of the scour marks could present a suitable substrate for Lophelia. From the videos there is no evidence of Lophelia along the pipeline route or in the Corrib Field itself. It should be noted that Lophelia has been recorded in deeper water to the south and west of the Corrib Field, but within the Erris and Slyne troughs (IOOA, 1998).

7.2.2.2 Landfall and Sruwaddacon Bay

A walkover survey was carried out by Aqua-Fact in July 2000, of the intertidal zones at the upper and lower pipeline crossings, and at the landfall location, as shown in Figure 7.5. In addition, cores (0.01 m2) were taken along transects from a number of tidal heights (where the substrate was soft) at these crossing points. The samples were sieved over a 1 mm mesh, and the invertebrates found were identified and counted. The sampling points from the 2000 survey are shown in Figure 7.5.

An additional marine ecological study of the Sruwaddacon Bay crossing points and pipeline landfall was undertaken by EcoServe in June 2001, to build on the information collected in the previous survey. The upper and lower pipeline crossings and the pipeline landfall were all sampled from the shore at low water during spring tides.

Upper Crossing Point

In 2001 littoral habitats and communities (biotopes) and fauna and flora on the upper shore were mapped, in order to provide an assessment of the marine/estuarine fauna, flora and habitats present. Particular attention was paid to the site of the proposed pipeline crossing and to adjacent shores. Here transects down the shore on both sides of the Sruwaddacon were examined and quantitative samples taken from each of the main biotopes. Three stations were examined on the north shore and two on the south

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shore. Species lists were compiled and organisms were identified to species level where possible. The biotopes on the shore were mapped using techniques developed by the SensMap project (Emblow et al. 1998). The results were compared to existing data and interpreted using the biotope classification (Connor et al., 1997). An explanation of the biotope classification is provided in Appendix 7.1.

Figure 7.5: Locations of landfall and upper and lower crossing points and shoreline invertebrate sampling locations from 2000 Four replicate core samples were taken at each station, which were then passed through a 0.5 mm mesh sieve, preserved, and returned to the laboratory for identification of organisms to species level.

Lower Crossing Point

The littoral habitats, communities, fauna and flora were examined at both sides of the Sruwaddacon at the lower crossing point and a species list was compiled. Descriptive information of each site was gathered to supplement previously collected data.

Landfall Site

The littoral habitats, communities, fauna and flora were examined at the pipeline landfall location and a species list was compiled. Descriptive information was gathered to supplement previously collected data.

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Underwater Photographic Survey

In addition to the above, Aqua-Fact undertook a photographic survey of the seafloor at the landfall site and the lower crossing point of the Sruwaddacon. The landfall transect began in about 5 m water depth, following the line of the proposed pipeline landfall. The lower crossing point transect followed the line of the pipeline route, as it crosses the Sruwaddacon near Rossport.

7.3 Receiving Environment

7.3.1 Offshore

7.3.1.1 Benthic Communities

Corrib Field

From the 27 stations within the Field, 261 different benthic taxa were recorded. Many of these species have been previously unrecorded from Irish waters, reflecting the very small amount of invertebrate taxonomic work which has been carried out in slope waters (Aqua-Fact, 2000). The taxonomic results from the Corrib Field samples are shown in Figure 7.3.

Anemones were present in virtually all the samples while Edwardsia and the sea pen Virgularia were scarce. Some sipunculids (Golfingia) and nemerteans were noted. The polychaete worm fauna was well developed, with ampharetids, capitellids, amphinomids, paraonids, flabelligerids, glycerids, goniadids, lumbrinerids, nephtyds and terebellids common. Aplacophorans (Neomenia and Chaetoderma) were also common, whereas only one pogonophore was recovered. Crustacean fauna was well represented, with cumaceans, isopods and amphipods being the most frequently noted groups. Echinoids (sea urchins) and ophiuroids (brittlestars) were the most abundant echinoderms present. The irregular echinoid Spatangus raschii was not common in the samples and only small specimens were recovered, despite Le Danois (1948) noting that this species was a characteristic element of the benthic infauna off the west coast of Ireland.

Small numbers of organic pollution indicator species were identified at a number of sites in the vicinity of the Corrib Field, including the polychaete worms Capitella and Cirratulus. As these species were not identified at the reference sites (Ref 1 and Ref 2), this may be attributed to the discharge of synthetic based mud (SBM) on cuttings from the exploration and appraisal wells drilled between 1996 and 2000 in the Field. However, the fact that these organisms are only recorded in low numbers and that they do not dominate the samples taken at these sites (as shown in Figure 7.3), suggests that any pollution is minimal. Future wells drilled in the Corrib Field will not discharge organic based mud cuttings, as all cuttings and associated drill fluid from well sections drilled with such muds will be transported to shore for disposal.

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In order to assess the similarities between the invertebrate populations at each of the Corrib Field sites, a dendrogramme was generated. Construction of the dendrogramme is based on the species and numbers of individuals of those species found at each site (this data is also presented in Figure 7.3, the data is transformed so that the numbers of individuals are based on a uniform unit of area. The degree of similarity between sites is shown on one axis (in Figure 7.3 it is the X-axis). From Figure 7.3 it can be seen that the Corrib sites were split into three main clusters, the first major differences are found at around 23% similarity, where a cluster containing all the Z sites, the two reference sites and F2-F4 split out. Site F1 then split out from the other “C” cluster at around 35%.

The “Z” cluster contains 15 stations, which are all in relatively close proximity to well 18/20-2z (18/20-4 was not drilled when the samples were taken), and the two reference stations. However, the two reference stations split out from this cluster and each other at around 52%. The “C” cluster contains the remaining 9 sites, which are generally concentrated round wells 18/20-1, 18/25-1 and 18/20-3.

Site F1 at well 18/20-1 showed the greatest level of macrofaunal disturbance within the field. The macrofaunal population here indicated a paucity in abundance and species number, when compared to uncontaminated sites in the same area. The reason for this separation in the community is probably the high rate of organic recovery and the extended duration of the impact at this site (4 years between drilling and biological sampling). This has advanced the progression within the community structure at 18/20-1 through more stages than at any other sites drilled more recently. Consequently, as the level of organics falls back to baseline levels, the distribution of the fauna is expected to follow a similar trend.

The faunal communities immediately surrounding the 18/20-3 and 18/25-1 wells and some of the outer stations indicated a similar, but less marked impact to that recorded at 18/20-1. Should the same rate and level of recovery (in terms of reduction in SBM related organic material, see Section 8) be replicated for these wells as were recorded at 18/20-1, then a similar level of community succession is expected and consequently, alterations to the biological population. Invertebrate populations at sites around well 18/20-2z (the “Z” cluster) showed least disturbance, and clustered more closely to the reference stations. This would suggest that the level of impact caused by the ester based drilling mud1 was insignificant. The chemical sampling surveys show that the levels of organic material in the sediments surrounding 18/20-2z were originally low and reduced significantly between 1998 and 2000.

Also provided in Figure 7.3 are the diversity indices for the Corrib Field sites and the number of individuals per 0.5m2. Diversity is a measure of the number of different species and their relative abundance in a sample, richness relates to the number of species in a sample, and evenness to the spread of the total number of individuals in a sample between the number of

1 Well 18/20-1 drilled with Ecomul (based on poly (PAO) and linear alpha olefin (LAO)) and paraffin, subsequently formulation of Ecomul changed, with elimination of PAO. Newer formulation of Ecomul used to drill 18/25-1 and 18/20-3. Esterkleen (ester based mud) used to drill 18/20-2z.

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species recorded. These are summarised in Table 7.1. To calculate the various indices, the faunal data were transformed using log2 for diversity and richness, and loge for evenness. Diversity was calculated using the Shannon-Weiner diversity index (Pielou, 1975), evenness as described by Pielou (1975) and richness by Margaleff (1958). These indices are compared below with those found in samples taken to the west of Shetland by the Atlantic Frontier Environment Network (AFEN).

Table 7.1: Range of statistics from the 27 Stations within the Corrib Field Station Value

Highest number of species Z8, Z12 73 Lowest number of species C4, F1 26 Highest number of individuals1 per 0.5m2 Z7 1220 Lowest number of individuals C1 115 Highest diversity value F9 5.05 Lowest diversity value Z1 2.63 Highest richness value Z8 7.73 Lowest richness value F5 3.51 Highest evenness value C1, F9 0.91 Lowest evenness value Z1, F4 0.47 1 - the number of individuals is calculated based on the same number of replicates (i.e. the seabed area sampled by 2 replicates (of 0.1 m2) is multiplied by 2.5, and that sampled by 3 replicates is multiplied by 1.67 to obtain a density of individuals per 0.5 m2). The number of replicates taken at each site is provided in Figure 7.3.

A Spearman rank correlation analysis was performed on the Corrib Field invertebrate data and on the sediment physical data (Appendix 8.1) to assess whether species distribution was related to substratum type. There were no ecologically significant correlations, and the results of this analysis are therefore not presented.

Comparison with Other Areas

In order to place the benthic macrofaunal data from the Corrib Field in context with other data from deep-sea locations worldwide (particularly the Atlantic Frontier Environmental Network (AFEN) region to the north of the Corrib Field), a report was prepared by Gardline (Gardline, 2001). Species diversity and abundance were compared at several locations, using univariate methodology (e.g. Shannon-Wiener index).

The results of the study show that, in general, the Corrib Field seemed to have both lower macrofaunal abundance and diversity, in terms of species richness and evenness, than the AFEN locations. Superimposed on this trend was the local effect of drilling activities within the Corrib Field. These observations are discussed in more detail below:

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Macrofaunal Abundance:

Although the abundances of macrofauna from both the Corrib and AFEN locations were relatively comparable on a global scale (abundances were low to intermediate compared to other deep-sea locations worldwide), in isolation the abundances recorded in the Corrib Field were lower (average number of species 50, compared to 65 in the AFEN 1998 survey and 53 in the AFEN 1996 survey).

The data from the Corrib location showed a large variation in abundance within the same depth range. This could possibly indicate the presence of a stress gradient, with particularly high and low values representing the effect of disturbance on macrofaunal density. These observed variations in abundance were probably due to organic enrichment and sediment variation resulting from the drilling activities in the area.

Macrofaunal Diversity:

The diversity values recorded from both the Corrib and AFEN locations were also generally lower than most deep-sea sites worldwide. The overall average species diversity in the Corrib Field was found to be lower than at AFEN locations of similar water depth (diversity 4.5, compared to 5.0 in the AFEN 96 and 98 surveys). The average evenness of species distribution was also found to be lower in the Corrib Field (evenness 0.7, compared to 0.85 in the AFEN 96 and 98 studies). The number of species at certain stations in the Corrib Field was, however, found to be as high as the highest values recorded during the AFEN studies, contrasting the lower overall diversity values observed. This apparent contradiction could partly be explained by the uneven species distribution in the Corrib Field, resulting in the lower overall diversity.

Seabed Photography

Figure 7.3 provides a number of seabed photographs taken both from above the sediment, and cross-sections through it. In several of the photographs the burrows of the squat lobsters (Munida sp.) can be seen, and a squat lobster can be seen in photograph JN336F9 from site F9. In other photographs (i.e. JN336F5, from site F5), polychaete worm casts can be seen, and several worm tubes can be seen on the surface photographs from sites F3 and F8. At site C2 the seabed photograph shows what appears to be an accumulation of drilling mud, and this may be the reason for the relatively low levels of species and individuals at this site. It should also be noted that at site F1, which, from the grab sampling appears, to be the most mud affected site, there are numerous burrows which could indicate that the site is well on its way to recovery. One of the reference sites (Ref 2) appears to have a different sediment type to that at the other sites, and this is probably the reason that it splits out from the other sites in the dendrogramme at around 50%.

Pipeline Route

The faunal taxonomy results from 12 stations sampled along the pipeline route from the Field to the outer part of the landfall area are presented in

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Figure 7.4. Water depth generally increases with station number; i.e. Stations 1 and 2 are the shallowest and Station 38 is the deepest.

There is very little information on the seabed sediments and associated benthic communities of the shelf to the west of Ireland (Boelens et al., 1999). The groupings broadly follow Thorson (1957) and the community distributions are as presented in Boelens et al. (1999). Station 8 is a Chamelea gallina community with other bivalves such as Fabulina and Mactra being present. The amphiurid Amphiura brachiata was also recorded. This type of faunal assemblage is associated with coastal sands and is widely distributed around the Irish coast. Station 10 is an Amphiura filiformis assemblage and can be regarded as being at the muddier end of a continuum between this type of community and the Chamelea gallina community. This type of community is also well represented in Irish coastal waters. The community at station 20 is a less species diverse group, and for that reason is more difficult to attribute to a group. It may, along with stations 25 A, B and C, be a Chamelea-type assemblage. Station 32 is an A. filiformis–type assemblage while the fauna recovered from station 38 has very strong similarities to that recorded at the Corrib Field sites, with Paramphinome jeffreysii, Thyasira ferruginea, Yoldiella, Cuspidaria and Munida, being present.

The shallowest stations (1-4) had fewer species and individuals than the other pipeline route sites, this is due to the regular wave disturbance of the sediments in that area.

Seabed photographs are provided in Figure 7.4 for many more pipeline route stations than grab samples were taken from. It can be seen from the photos that the sediments along the route vary from sand to gravel and cobbles. Many of the photographs show a relatively bare sediment, but fauna can be identified at stations 41A (sea urchin), 30A (anemone), 20 (fish) and 12 (on previously considered alternative pipeline route) (encrusting fauna). A photograph from one of the shallowest subtidal stations is provided in Section 7.3.3.1 (Plate 7.3), where a shore crab can be seen on the sand rippled seabed. Sand and sand ripples are a major feature of all of the nearshore photographs presented in Figure 7.4, this is because the pipeline is to be routed through soft sediments as far as possible.

The whole of the pipeline route was surveyed using an underwater video. The surveys concentrated on areas of solid or consolidated sediment, e.g., iceberg scour marks, where there was potential for the coral Lophelia pertusa to be present. This species was not seen in any of the videos.

7.3.1.2 Planktonic Communities

The offshore planktonic (phytoplankton and zooplankton) communities at the production site and along most of the pipeline route are oceanic in character (Hardy, 1956), reflecting the high salinity, shelf edge water described in Section 9. Holoplanktonic taxa (species that spend their entire life cycle as plankton) such as siphonophores (Totten, 1965; Fraser, 1967), vellellids, the ctenophores Beroe and Bolinopsis (Fraser, 1962), the polychaetes Lopadorhynchus and Greefia (Southern, l908), the chaetognath

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Krohnitta, the copepod Anomalocera, euphausids, salps and the gastropod Ianthina (Fraser, 1962), are all typical examples of oceanic forms which would occur in the general area. The zooplankton would also comprise larval stages of crustaceans and fish species that occur in the area. This oceanic water is typically kept offshore during the autumn, winter and spring months by a lower salinity, inshore band of water, which has its own planktonic flora and fauna.

7.3.1.3 Fisheries

Fisheries information is discussed in two parts of Section 7.3, both below, where the emphasis is upon the offshore fishing activity, and in Section 7.3.2.3, where nearshore catches (mostly shellfish) are considered. The division of the discussions is not a strict one, but reflects the current method of catch data compilation by the DOMNR. Data for submission by DOMNR to the International Council for the Exploration of the Seas (ICES) are compiled from the statutory catch log sheets submitted by vessels of larger size than approximately 10 m. Further data is collected on a port by port basis for landings by smaller vessels.

In order to record the catches from various sea areas, ICES divides the seas into zones, the Corrib Field and pipeline route lie within ICES zone VIIb (Figure 7.6). These zones are further divided into blocks of approximately 30 by 30 nautical miles, Figure 7.7 shows that there are three ICES blocks (37D8, 37D9 and 37E0) through which the Corrib pipeline will be laid.

Figure 7.6: ICES rectangles around the west coast of Ireland

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Figure 7.7 also provides the tonnages of shellfish, and demersal and pelagic finfish catches in each of the ICES blocks surrounding the Corrib development. These figures have been provided for 1998 and 2000 by the DOMNR (2001) from the statutory catch return forms (data from 1999 is incomplete). Wherever a vessel lands its catch, it’s log book records will allocate the relevant tonnage of various species to the ICES block where the catches were made. It is the intention of ICES that these figures, which are submitted on a country by country basis are compiled centrally to provide a total tonnage caught per area. This data can then be used to estimate stock sizes and allocate total allowable catches (TACs) for future years. However, while vessels from several European countries also fish in the waters to the west of Ireland. The data provided in Figure 7.7 relates solely to the catch returns from Irish vessels.

Figure 7.7: Catch data (tonnes) from ICES blocks in the vicinity of the Corrib Field and pipeline route

The majority of the catch submissions by Irish vessels for the area shown in Figure 7.7 come from the major west coast ports such as Killybegs, where the larger vessels are based. All catches are registered at the smaller ports as well. In the case of smaller, coastal vessels, their catches are also recorded by port of landing by the DOMNR.

In many cases these smaller vessels catch higher quantities of shellfish than the larger vessels, and this is the case for block 37E0, where Broadhaven Bay is located. The log sheet returns by area (larger vessels) show catches of only 1 and 5 tonnes of shellfish in the years 1998 and 2000 respectively for

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block 37E0, while the catch data by port indicate that more than 290 tonnes of shellfish were landed by small boats into ports in that area 1998. The catches by these smaller vessels are discussed further in Section 7.3.2.3, while the offshore catches are discussed further in this section.

Demersal Fisheries

Demersal species are those that are found on or near the seabed. The most important demersal species in the vicinity of the Corrib Field and pipeline route include haddock (Melanogrammus aeglefinus), hake (Merluccius merluccius), cod (Gadus morhua), anglerfish or monkfish (Lophius piscatorius), megrim (Lepidorhombus whiffiagonis), whiting, (Merlangius merlangus) brill (Scophthalmus rhombus), plaice (Pleuronectes platessa), saithe (Pollachius virens) and sole (Solea solea) (DOMNR, 2001).

There are spawning grounds off the Mayo coast for all of the above species and the spawning period for most species is between late winter and spring. Eggs and young fish are pelagic and the larvae can stay in the plankton for up to six months.

The area around the Corrib Field is actively fished by Irish, French, Spanish and other European trawlers in waters from 200 - 450 m depth (as shown in Figure 7.8). Irish vessels do trawl the shallower ground, but in some areas along the pipeline route the ground is rough and difficult to fish.

Figure 7.8: Areas of main demersal fishing activity (Jee Associates, 2000) Demersal catch data per ICES block, shown in Figure 7.7, indicate that by tonnage the demersal catch is much smaller than the pelagic catch for all blocks where data are presented. However, while the tonnages may be

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smaller, it tends to be the case that the demersal landings command a higher price per kilo.

Block 37D8, in which the Corrib Field lies, provided relatively high catches of demersal species in both 1998 and 2000. The only other block (from which data are presented) where higher tonnages of demersal catches were recorded was 38E0, an area which is closer to the shore (Figure 7.7). The general pattern of demersal catches is that they decrease generally with distance offshore and depth, possibly reflecting a reduction in the level of fishing effort. However, block 37D9, in which the majority of the Corrib pipeline route lies, yielded lower tonnages of demersal catch in 1998 and 2000 than 37D8. An important factor here may be the suitability of the sediment for demersal trawling – which is more difficult over rocky ground.

The demersal catch data compiled by the DOMNR is provided on a per block basis (30 x 30 nautical miles). The Marine Institute regularly carries out scientific demersal trawls in the vicinity of Broadhaven, round to the west of the Mullet peninsula and in Donegal Bay. Information from these trawls can be used to complement the data from the DOMNR, and to estimate the importance of various demersal species in different areas.

Trawls have been carried out on an annual basis at ten locations between 1993 and 2000. The trawls were carried out for approximately 1 hour at each site using a standard trawl net, usually in the month of October. The catches were weighed and the species identified. The percentage make-up, by weight, of the trawl of the most important commercial (demersal) species has also been calculated (these “commercial demersal” species were allocated by the Marine Institute, and include scad/horse mackerel, which could be considered by some to be a pelagic species). Figure 7.9 provides pie-charts showing the average make-up of the commercially trawled species at each site over the 8 year period to date. The pie charts are centred on the “average location of the trawl” and are sized to proportionally represent the average weight of the catch per hour. The largest average catch is found at site 24 (434 kg/hr) for a combination of the species whiting, sole, cod, haddock, hake, plaice and horse mackerel. By comparison, the average catch from Broadhaven Bay (site 25) was 140 kg/hr. Table 7.2 provides the average catch per hour data which was used to compile Figure 7.9.

Using the Marine Institute survey and DOMNR compiled data, it can therefore be concluded that haddock and whiting generally provide the greatest catches, being followed by scad (horse mackerel) and plaice.

Pelagic Fisheries

Pelagic species are those which, as adults, live in mid-water. In the offshore area mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus) are commercially important pelagic species. However, fishing for these species is seasonal, and occurs mainly in the spring and summer months. Herring (Clupea harengus) is an important species trawled nearer to the shore, and particularly in Donegal Bay.

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According to DOMNR catch information, other important pelagic species include sprat (Sprattus sprattus) and blue whiting (Micromesistius poutassou). In block 38E0 horse mackerel and sprat provided large catches, while in 38D9, blue whiting was important and in 37E0 mackerel formed a large proportion of the pelagic catch.

Figure 7.9: Relative size catches for all seven commercial demersal species at ten sites fished by the Marine Institute

Table 7.2: Average weight of commercial demersal species in Marine Institute trawls at ten stations catch (Kg/hour) commercial demersal species All Site ICES Sole Cod Haddock Hake Plaice Scad Whiting Total species Block Total 18 38E0 0.28 2.65 177.16 12.53 1.69 11.81 146.20 352.32 392.19 19 37E0 3.25 10.10 196.50 5.46 1.54 28.94 181.88 427.66 449.66 20 37E0 3.18 2.35 22.87 0.00 26.14 5.04 115.69 175.28 286.10 21 37D9 0.15 4.72 186.91 4.31 0.06 23.68 4.73 224.55 282.61 22 37D9 0.61 0.41 224.19 14.15 4.84 19.42 161.93 425.54 870.41 23 38D9 0.00 1.50 210.87 2.34 1.52 55.29 72.50 344.03 395.88 24 38E0 0.78 0.00 61.32 5.01 36.86 38.10 292.65 434.72 697.85 25 37E0 5.91 0.44 16.79 0.00 39.45 6.63 70.55 139.77 383.28 26 38E0 2.91 4.58 107.46 2.04 2.76 61.19 62.95 243.89 482.08 27 38E0 0.00 3.85 114.76 3.65 0.05 106.66 28.26 257.23 290.51

Relatively low pelagic catches were recorded in block 37E0, however, it should be noted that the actual sea area of that block is significantly less than several of the other blocks for which data are provided. Block 37E9

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yielded a slightly higher than average pelagic catch than some of the other coastal blocks. Block 37D8, in which the Corrib Field lies, yielded significantly less pelagic catch than 36D8 and 37D9, to its south and east respectively, but more than the blocks to its west and north.

While Marine Institute survey trawls (see Section 7.3.1.3) were designed to catch demersal species, they also caught pelagic species. The weight of all species caught was recorded and the data showed that herring formed a large percentage of the pelagic fish in the catch in blocks 37D9, 37E0 and 38E0, mackerel were important in blocks 37E0 and 38E0, with small amounts of argentine trawled in blocks 37D9 and 38E0. Figure 7.10 provides an indication of the total catch (kg/hr) for all species in the Marine Institute trawls, including the pelagic species, it can be seen that the highest average catch per hour approximately doubles from 434 to 870 kg/hr when the pelagic species are included and there are changes in the relative catch sizes from the different sites.

Figure 7.10: Average total catch data (kg/hr) from ten sites trawled annually by the Marine Institute Besides the smaller pelagic species, albacore tuna (Thunnus alalunga), bluefin tuna (T. thynnus) and swordfish (Xiphias gladius), occur off the west coast, but are not currently fished intensively. These species are highly prized both in terms of their meat and also as big game species and plans are underway to exploit these stocks.

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Shellfish

The most important shellfish species caught offshore in the vicinity of the Corrib Field and pipeline route are Dublin Bay prawn/Norway lobster (Nephrops norvegicus) and squid. The shellfish catches provided in Figure 7.7 represent these species with the addition of crab in areas closer to shore. It can be seen that shellfish catches vary significantly over the area shown in Figure 7.7. This may be a reflection of the suitability of the substrate for the crustaceans, particularly in the more offshore areas. The large difference in shellfish catches between 1998 and 2000 in Block 36D7 may be a result of a change in effort or fishing success for squid, which move around in large shoals.

7.3.1.4 Seabirds

Seabirds are present throughout the year off the Irish west coast and there are strong temporal trends, not only in densities, but also in species present.

Offshore, oceanic species include gannet (Morus bassanus), fulmar (Fulmarus glacialis), Manx shearwater (Puffinus puffinus), storm petrel (Hydrobates pelagicus) and passage migrants, e.g., great, Cory's and sooty shearwaters (Puffinus gravis, Calonectris diomedea and P. griseus), great, Arctic and pomerine skuas (Catharacta skua, Stercorarius parasiticus and S. pomarinus).

The Cetacean and Seabirds at Sea team of the Coastal Resources Centre at the University College Cork (CRC) recently carried out a series of marine surveys off the Irish coast on behalf of the RSG and the PSG (CRC, 1999). The survey area concentrated to a large extent on the Irish West Coast and focussed on the Porcupine Sea Bight, the Porcupine Bank, the Erris/Slyne Trough and the eastern side of the Rockall Trough. The survey period covered the months July - December 1999. Additional data were collected between December 1999 and October 2000 (Mackey et al., 2000). New data presented by CRC (Mackey et al., 2000) have helped to give a fuller picture of the pattern of seabird distribution in and around the field.

The CRC report lists a variety of species, notable amongst which are Wilson's and Leach's petrels (Oceanites oceanicus and Oceanodroma leucorhoa) and Sabine's gull (Larus sabini). It is likely that other migrant species, e.g., glaucous gull (Larus glaucos), may also occur in the area.

Mackey et al. (2000) have mapped the number of species recorded for all areas surveyed in the period July 1999-October 2000. This reveals that the area around Corrib has low (1-4) to moderate (5-9) numbers of species present

All seabirds are susceptible to oil contamination. Although Corrib is a gas field, liquid hydrocarbon inventories, such as diesel oil, will be used to power machinery on the drilling rig and supply and support vessels. There is, therefore a low risk of a small oil spill. The species present at, or in, the vicinity of Corrib and their susceptibility to pollution, is presented in Table 7.2.

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Table 7.3: Seabird species and their vulnerability to oil pollution in the vicinity of the Corrib Field Species Vulnerability Reason(s) for Seasonality Abundance (Moderate, vulnerability (when present) (low, high, very high, moderate, unknown) medium, high) Fulmar Moderate None given summer/autumn Low Great Not given Unknown Autumn Low/Moderate shearwater Gannet High P Probable Probable summer/autumn Low/moderate Ranking Criteria: W = species spends a substantial period of its life on the water surface P = waters west of Britain are important for a large proportion of the species U = unknown vulnerability. Indicator not provided in Tasker et al. (1990) Not all species are considered to be at the same level of risk. Tasker et al. (1990) produced a vulnerability index, using a composite figure of all species vulnerability, to produce maps of seabird vulnerability. Mackey et al. (2000) have adapted this method to give each species a vulnerability level – moderate, high, very high or unknown. In addition, the reasons for the ranking of each species are provided, based on one or more criteria.

In summary, the seabird sensitivities around Corrib area relatively low, with a restricted number of species present at relatively low abundance.

7.3.1.5 Marine Mammals

Cetaceans

The waters off the north-west coast of Ireland have historically been important habitats for cetaceans and supported two whaling stations in County Mayo in the period 1908-1923. The main species taken by these stations were fin whales (Balaenoptera physalus), however, blue (B. musculus), sei (B. borealis) and sperm whales (Physeter macrocephalus) were also taken. The stations closed for commercial reasons, as the volume of products from these stations could not compete with imports from other countries (Fairley, 1981).

The Atlantic Frontier Environmental Network (AFEN), supported by the Irish Offshore Operators Association (IOOA) members, commissioned a study of the large baleen whales in the waters around Britain and Ireland. The study used bottom-mounted hydrophone arrays to monitor the vocalisations of fin, blue and humpback whales (Megaptera novaeangliae). The study covered 12 overlapping regions from the Faroe-Shetland area down to the Bay of Biscay.

Fin whales were the most frequently detected calls, occurring in all regions in every month of the year, with highest whale counts occurring between October and January and minimal levels in May through to July. Blue whales were detected in all latitudes, with peak detection rates off Western Ireland in November and December, declining to minimal levels in March through to June. From the data there appeared to be no systematic seasonal

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migrations for these two species (Clark & Charif, 1998) and the general pattern of seasonal variability was similar in both years (1996-1998) (Clark and Charif, 2000).

Humpback whales were the least frequently detected species, occurring in only the four most northerly regions, and only from November through to April. Data from the four regions show a poorly defined trend, suggesting a north to south progression in peak humpback numbers from early January to mid March.

Information on the smaller non-commercial species is limited. However, surveys indicate that this area has high species diversity and relatively high abundance.

A dedicated visual and acoustic survey of cetaceans off the Mayo coastline in 1993 (Gordon et al., 2000) recorded six species during 20 days at sea, mainly consisting of long finned pilot whales (Globicephala melas) (27%), common dolphins (Delphinus delphis) (19%), white-sided dolphins (Lagenorhynchus acutus) (15%) and minke whales (Balaenoptera acutorostrata) (15%). Harbour porpoise (Phocoena phocoena) and bottlenose dolphin (Tursiops truncatus) were also recorded, the former inshore (<12 nmls) and the latter in association with pilot whales on the shelf edge. Overall cetacean vocalisations were recorded on 29% of monitoring sessions throughout 480 hours of surveying (Gordon et al., 2000).

Of the 23 cetacean species recorded in Irish waters, at least 17 of these have been recorded off the north-west coast of Mayo (see Table 7.4) and are considered to inhabit the study area, at least on a seasonal basis. Some of the cetacean species recorded (blue and humpback), are severely depleted following exploitation but have been recorded in recent years, suggests that these populations may be recovering (Evans, 1991). Very rare species, such as blue whales, were also recorded and may actually occur more frequently than formerly expected (Clark & Charif, 1998). Two species, harbour porpoise and bottlenose dolphin, are on Annex II of the EU Habitats Directive and they and their habitat are entitled to full protection (Berrow, 2000).

The information outlined in Table 7.4 is supported by other studies conducted in the area, such as the dedicated cetacean survey completed by the Cetacean and Seabird Team of the CRC in August 2000 on behalf of the RSG and PSG. The survey area focused on the Porcupine Sea Bight, Porcupine Bank, the Erris/Slyne Trough, and the Rockall Trough and recorded bottlenose dolphins, common dolphins and Atlantic white-sided dolphins and striped dolphins.

During the 1997 seismic survey of the Corrib Field, sightings of cetaceans were made and forwarded to JNCC (Joint Nature Conservation Committee) in the UK. These records show that large numbers (generally 50-100, including a record of 200-300) of cetaceans were observed periodically during the period 23rd June – 24th July. Details of the species were not recorded.

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The location of seasonal feeding and calving areas have yet to be established, however the CRC expect to produce information on regionally important areas by the end of summer 2001.

In summary, the area offshore from Mayo is important for cetaceans. A number of threatened species, including blue and sei whales, have been recorded, as well as more common species such as Risso’s and common dolphins.

Enterprise, through the RSG, will continue to fund further research into the cetacean populations west of Ireland, including the Corrib Field and pipeline route, over the next year.

Table 7.4: Cetacean species recorded off north-west Mayo (adapted from Berrow, 2000) Species Relative Frequency of Conservation References abundance Sightings Status

Harbour Common Peak in Aug - Annex II 3,5,6 porpoise inshore, see Nov species White-beaked Frequent Most frequent 3,5,8 dolphin late summer White-sided Abundant Most frequent in 3,4,6,8 dolphin offshore summer Common Abundant Most frequent in 2,3,6,8 dolphin summer Bottlenose Frequent Most frequent in Annex II 5,6,8 dolphin summer species Striped dolphin Occasional Most frequent in 3,8 summer Killer whale Regular Peak in May - 3 Dec Risso’s dolphin Common Peak in April - 2,3 Sept Long-finned Abundant Peak in Oct - 3,6, 7 pilot whale offshore March Northern Unknown Peak in April - Depleted 3,5 bottlenose Oct whale Cuvier’s beaked Unknown All year 3,9 whale Sperm whale Frequent All year, peak in 1,3,9 offshore July-Nov Humpback Rare Peak Nov – April Extremely 1, 7 whale depleted Blue whale Rare Peak Nov – Dec Extremely 1, 7 depleted Fin whale Common Peak Oct – Jan 1,3, 7 Sei whale Rare Peak June- 1,9 December Minke whale Frequent Peak April - Oct 3,6, 7 1. Fairley (1981). 2. Berrow (1993). 3. Berrow & Rogan (1997). 4. Couperus (1997). 5. Evans (1991). 6. Gordon et al. (2000). 7. Clark & Charif (1998). 8. Seawatch Foundation (2000). 9. Biodiversity Library (2000).

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7.3.2 Nearshore

7.3.2.1 Benthic Communities

The results of the faunal analyses from the four shallowest subtidal sites along the pipeline route show a reduced fauna, particularly at stations 1 and 2 (approx. depth 2 m). Polychaetes (Nephtys cirrosa and Spio filicornis) and amphipods (Bathyporeia elegans and Pontocrates altamarinus) were the most characteristic species of these samples. Stations 3 and 4, which were in somewhat deeper water, ca. 5 - 7 m, had a more diverse fauna, with additional polychaete and crustacean taxa, and one species of echinoderm, Echinocardium cordatum. This community is typical of shallow water, high energy, inshore sandy communities and is found in several areas around the Irish coastline (Boelens et al., 1999). The numbers of species found in these four sites, and the locations of the sites are shown in Figure 7.4.

The BioMar survey (Picton and Costello, 1998) examined ten subtidal sites within Broadhaven Bay. Most of the sites were along the west side of the bay, however one site, S of Rinroe Point, was close to the proposed pipeline route (Figure 7.11). There the seabed was a mixture of broken bedrock, boulders and cobbles, with sparse kelp Laminaria hyperborea. Kelp was restricted to the larger boulders, with an understorey of red foliose algae, particularly Delesseria sanguinea and Heterosiphonia plumosa. Boulders also supported the ascidian Aplidium nordmanni with the bryozoan Scrupocellaria reptans. A lot of drift algae was present between the boulders. This site is likely to be typical of large areas of the seabed through which the pipeline will be laid within Broadhaven Bay. None of the species recorded from this site were of specific nature conservation interest or of commercial importance. All species have previously been recorded around the coast of Ireland (Picton and Costello, 1998). A list of the species found at this point and their relative abundances is provided in Appendix 7.2.

In comparison sites on the west of the bay were primarily bedrock leading down to mobile sand in the outer reaches of the bay. The sand was characterised by the bivalve Lutraria lutraria and the burrowing urchins Echinocardium spp. Full descriptions of the sites on the west of the bay are provided in Appendix 7.2.

Bedrock communities along the western shore were subject to a range of wave exposures, from very exposed toward the entrance of the bay to very sheltered towards the inner bay. The bedrock is generally steep sloping, forming ridges and gullies. The shallower rock at sites towards the entrance to the bay are characterised by dense kelp Laminaria hyperborea forests, with an understorey of red algae. Below this the kelp is more sparse and the dominant understorey algae are the brown seaweeds Dictyota dichotoma and Dictyopteris membranacea, with some red algae Delesseria sanguinea. Gullies and small cliffs subject to high water movement were dominated by the jewel anemone Corynactis viridis and Dead Man’s Fingers Alcyonium digitatum. Deeper rock along the western shore supported a community dominated by sponges, in particular species from the Axinellida order.

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Shallow wave-surged caves occur along the western shore and support a range of species, including the anemones Phellia gausapata and Parazoanthus anguicomus and the soft coral Alcyonium glomeratum. Sponges typical of cave communities such as Dercitus bucklandi have also been recorded.

Figure 7.11: BioMar survey locations within Broadhaven Bay

7.3.2.2 Planktonic Communities

The inshore planktonic community varies in composition and concentration, depending on the time of year. During the winter months, biomass levels are low and only a small number of species are present. With the increasing number of daylight hours associated with the onset of spring, there is a rapid increase in biomass, initially of the phytoplankton and, following this, the zooplankton. The latter comprises to a very large extent meroplanktonic species (species spending their larval stages in the plankton), such as medusoid stages of hydrozoans, larval polychaetes, gastropods, bivalves, crustaceans, echinoderms and other species including fish. Into summer, these larval forms settle out of the water column to begin life as juveniles on the sea floor. Biomass levels in the plankton progressively decrease as the summer progresses. During late summer/ early autumn, the high salinity offshore water moves closer inshore with its characteristic plankton community. As autumn proceeds, this oceanic water is forced back offshore by the low salinity and inshore current, and the planktonic communities decrease in biomass once again (Aqua-Fact, 2000).

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7.3.2.3 Nearshore Fisheries

The DOMNR records catches of shellfish and marine finfish from the individual ports in the vicinity of Broadhaven Bay, catches of salmon are recorded by the NWRFB. The DOMNR have provided catch records from 1998 (the latest complete set of data) for several ports (see Table 7.5)

Table 7.5: Catch data for landings at various ports in the vicinity of Broadhaven Bay for 1998, compiled by DOMNR Total Crawfish Lobster Crab ‘Other Finfish shellfish’ Ballyglass 118.2 1.7 4.6 7.3 33 Belmullet/Blacksod 0 0.6 3.3 13.1 22.4 Ballycastle 0 0 1.6 0 3.5 Porturlin 18.4 0.8 4.6 122.4 10 Enniscrone 0 0 0.2 0 3.3 Kilcummin 0 0 2.4 0 2.9 Killala 17.6 0.2 1.9 23.9 26.9 Lacken 0 0 0.4 0 0 Other shellfish = gigas oyster (cultured), blue mussel, cockle, velvet crab and periwinkles It can be seen that for finfish the greatest landings were at Ballyglass (main species being haddock, pollock, whiting and rays), while Porturlin was the most important for shellfish. Approximately 140 tonnes of shellfish were landed at Porturlin, of which 120 tonnes were either whole edible crab or crab claws. Killala was the second most important shellfish port, with 53 tonnes, 11 of which were farmed oyster.

The species which provided the greatest value was lobster (IR£210000), but by weight, the crawfish landed realised approximately twice the value per tonne of lobster. Of the catch across all of the above ports, 57% by weight was either crabs or crab claws, 27% was periwinkles and 6.5% was lobster.

Catches from Broadhaven Bay would have featured in the landings from several of the above ports, and the importance of the Bay in the local economy is recognised.

The Marine Institute site (see Figure 7.9) within Broadhaven Bay was trawled in seven of the eight survey years, and Table 7.6 provides a list of the species caught in Broadhaven Bay, together with the frequency with which they were encountered – ie. in how many trawls that species was recorded. Also provided in Table 7.6 is the percentage make up of the trawl weight by the individual species.

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Table 7.6: Fish species recorded by the Marine Institute in Broadhaven Bay 1993-2000 (no trawl in 1996). Figures in brackets represent the weight fraction of the average catch by individual species Common name No of times Common name No of times trawled trawled (% of trawl (% of trawl by wt) by wt) Whiting 7 (18.41) Blue whiting 2 (0.03) Merlangius merlangus Micromesistius poutassou Plaice 7 (10.29) Lesser spotted 2 (2.24) Pleuronectes platessa dogfish Scyliorhinus canicula Horse mackerel 6 (1.73) Herring 2 (26.16) Trachurus trachurus Clupea harengus Brill 6 (2.19) Lemon Sole 2 (0.06) Scophthalmus rhombus Microstomus kitt Megrim 6 (1.00) Norway pout 2 (0.08) Lepidorhombus Trisopterus esmarkii whiffiagonis Monk 6 (3.12) Cod 2 (0.12) Lophius piscatorius Gadus morhua Sole 6 (1.54) Dab 1 (2.70) Solea solea Limanda limanda Mackerel 5 (18.58) Common dragonet 1 (0.10) Scomber scombrus Callionymus lyra Haddock 5 (4.38) Grey gurnard 1 (0.22) Melanogrammus aeglefinus Eutrigla gurnardus Argentine 3 (0.12) Red gurnard 1 (0.01) Argentina sphyraena Aspitrigla cuculus Ray 3 (3.26) Poor cod 1 (3.23) Raja spp. Trisopterus minutus Turbot 3 (0.41) Sandeel 1 (0.02) Scophthalmus maximus Ammodytidae

It can be seen from the data that of the demersal species whiting, plaice and haddock are the most important commercial species in Broadhaven Bay. However, the pelagic species can provide much greater catches, if they are present – herring were only trawled in two of the seven trawls in Broadhaven Bay, but accounted for 26.2% of the average catch over the seven trawls. Mackerel were present on five occasions, and provided an average of 18.6% of the catch by weight.

Broadhaven Bay, whilst providing the lowest average catch per hour for the commercial demersal species (see Table 7.2), is nevertheless important in a local context, and is fished for other species not recorded by the Marine Institute, such as crab, lobsters and crawfish (spiny lobster). Several vessels also tangle-net for whitefish in Broadhaven Bay. During the salmon fishing season (June and July) approximately 16 vessels fish the Broadhaven Bay area. During 2001, these vessels landed approximately 5000 fish, a slight increase on 2000, with a market value in the order of IR£50,000 (NWRFB, pers comm).

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Nursery Areas

The Central Fisheries Board (CFB) has identified Ross Bay (to the north- east of Sruwaddacon Bay) as a nursery area for several fish species, including thornback ray (Raja clavata), dab (Limanda limanda), topknot (Zeugopterus punctatus) and turbot (Scophthalmus maximus). It is also understood that the thornbacks from the Ross Bay nursery area populate Broadhaven Bay.

Information from the Marine Institute (D. Stokes, pers comm.) indicates that within the vicinity of Broadhaven Bay, the most sensitive area in terms of fisheries is thought be that around the Stags of Broadhaven, off Benwee Head. The area is important as a spawning and nursery area, high productivity there may be due to a number of factors, such as the local oceanographic conditions and seabed type. The area has been clearly identified by local fishermen and from scientific (acoustic, larval and egg) surveys as being significant for juvenile fish, particularly herring.

Aquaculture / Shellfishery Activities

Except for an area in the inner part of Broadhaven Bay and to the south of Belmullet in the northern part of Blacksod Bay, the north-west coast of Mayo has been little developed in terms of aquaculture activities. In Blacksod Bay there is a developing oyster-culture industry, however, at present, the scale is limited. A licence for oyster culture exists for a location in the Sruwaddacon, close to Pollatomish Pier, however, it is understood that very little culture is carried out from the site. An abalone farm has also been proposed for the inner Broadhaven Bay area, between Brandy Point and Belmullet. The locations of the licensed aquaculture areas in Broadhaven Bay are presented in Figure 7.12. Due to the very exposed nature of the open ocean coastline from the west side of the Blacksod Peninsula east almost as far as Sligo town, it is considered that there is limited potential for the aquaculture industry to develop in this area.

Capture fisheries for lobster (Homarus gammarus) and crab (Cancer pagurus) are relatively well-developed along the Broadhaven coastline (and further offshore for crab), due to the preponderance of rocky substrates close to the shore. There is a local shellfish co-operative based at Porturlin which manages this resource. This fishery is seasonal, being concentrated in the summer months when weather conditions are suitable for the relatively small vessels (< 10 m) to safely deploy and recover pots.

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Figure 7.12: Locations of licensed areas for shellfish cultivation in Broadhaven Bay

7.3.2.4 Seabirds

Pollock et al. (1997) recorded the following bird species in the general Broadhaven area: fulmar, Cory's shearwater, great shearwater, sooty shearwater, Manx shearwater, storm petrels, gannet, pomerine skua, Arctic skua, great skua, lesser black backed (Larus fuscus) and great black backed gull (Larus marinus), kittiwake (Rissa tridactyla), guillemot (Uria aalge), and puffin (Fratercula arctica).

Other species known to be found in the area are gannet (Sula bassana), fulmar (Fulmarus glacialis), cormorant (Phalacrocorax carbo), terns (Sterna spp.) and auk species. There are also both breeding migrants, e.g., terns, Manx shearwater, storm petrel and passage migrants, e.g., great, Cory’s and sooty shearwaters, great, Arctic and pomerine skuas, that pass by the west coast of Ireland in the late summer/early autumn months.

The period of most activity for coastal bird species is between March and June, when pairing, nest site selection, nest building, brooding and chick rearing occurs. All species of breeding residents and migrants tend to stay closer to shore during the breeding period (spring/summer), while in the late summer/autumn they tend to be dispersed over very extensive areas of coastal water.

During the post-breeding / pre-dispersion phase, many species go through a moulting period, when they have reduced flying capabilities. This is especially true of auks that are flightless during this time and are therefore

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highly susceptible to water-born surface pollution. Shearwaters, petrels and gannets are not as sensitive as they spend much of their time in flight.

The area around Broadhaven, Blacksod, Tullaghan Bay and parts of the Mullet peninsula has been designated as an Important Bird Area for Europe (IBA 041), and Blacksod Bay and Broadhaven are designated as a Ramsar site (see Section 7.3.4). Birds recorded within this general area include great northern divers (Gavia inmer), whooper swans (Cygnus cygnus), white fronted geese (Anser albifrons), barnacle geese (Branta leucopsis), brent geese (Branta bernicla), corncrake (Crex crex), bar-tailed godwit (Limosa lapponica), red-necked phalarope (Phalaropus lobatus) and sandwich terns (Sterna sandvicensis).

7.3.2.5 Marine Mammals

Cetaceans

The harbour porpoise and the common dolphin are thought to be the most common and widely recorded cetaceans in Irish coastal waters, the former being most common around the southern and western coasts. Some porpoises may be seen inshore at any time of the year, however, numbers are highest in most coastal areas between August and November.

In addition to the above, there may be a coastal population of bottlenose dolphins partially isolated from the offshore population along the Western coast of Ireland (Pollock et al, Loc cit.), as recent sightings in the deep waters (>1500m) fringing the Porcupine region show (O. O’Cadhla, pers comm.). A recent publication by Hayden & Harrington (2000) lists the main populations of Irish bottlenose dolphins as being present in Clew Bay, Galway Bay, Sligo Bay and the Shannon Estuary. It is also common knowledge that a group / or groups of bottlenose dolphins regularly frequent the waters of Killary Harbour in summer (O. O’Cadhla, pers comm.) The 2000 CRC survey also recorded a large group of bottlenose dolphins (20-30 individuals) to the west of Achill Head, whilst completing the “Corrib” transect. Bottlenose dolphins were also recorded off Achill Head during the BioMar survey (C. Emblow, pers comm.).

Data supplied by the IWDG from their sightings database cover an area within 20 nautical miles north/south and east/west of Broadhaven Bay, with Achill Island being the furthest point south and Downpatrick Head the furthest point east. The sightings, presented in Appendix 7.6 are all from the last decade with the exception of record 26.

Berrow (1993) gives details of a dedicated landbased survey carried out in 1992. The data gathered suggests that the north-west coast supports a relatively high abundance of cetaceans with Risso’s dolphin and Common dolphin recorded inshore. These data are supported by Gordon et al. (2000), who recorded common dolphins inshore off Achill Head and in Donegal Bay. Group size was generally small, with 40 being the maximum recorded. Minke whales were also recorded close inshore on four occasions within 5 km of the coast. Two sightings were made off Erris Head and two off St Johns Point. Overall sightings inshore were lower than may be expected although

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this could be partly explained by poor sighting conditions, seasonal fluctuations in abundance and the lack of hydrophones to detect Mysticete whales.

The CRC 2000 report (Mackey et al., 2000) recorded no large whales in the inshore areas through which the pipeline is routed, most notable is the absence of minke whale records between July 1999 and October 2000. Odontocete records include one Risso’s dolphin seen close to shore in November 1999. There is a surprising absence of harbour porpoise, bottlenose and common dolphin records.

Based on available information, the overall picture of inshore cetacean distribution is one of a relatively diverse range of species comprised principally Odontocetes and most frequently, Common, and Risso’s dolphin. There are also reasonable numbers of records of bottlenose dolphin and harbour porpoise. Minke whale have been confirmed as occurring inshore on several occasions. Other species must be regarded as being irregular or vagrant visitors to the area. The current data are limited and it is not possible to assess, with any accuracy, seasonal fluctuations in the abundance of specific species, or the overall species diversity. Based on current data, there is no evidence that Broadhaven Bay is of particular importance to cetaceans.

The Habitats Directive affords protection to coastal cetaceans in two ways. Annex II species, including bottlenose dolphin and harbour porpoise are nominated as species for which Special Areas of Conservation (SACs) may be designated where important areas for these animals occur. In, or adjacent to, such areas, proposed activities are subject to specific assessment by the appropriate authority in the light of the conservation objectives of the site. At present, there are no SACs in the area of the proposed development designated specifically for either of these two species, and therefore the need for an appropriate assessment, as required by the Directive, is not thought to be necessary. Annex IV (a) also makes provision for the protection of all cetacean species, specifically from the effects of ‘deliberate disturbance’, or destruction or deterioration of their breeding or resting sites.

Seals

Both common (Phoca vitulina) and grey (Halichoerus grypus) seals are known to occur all around the Irish coastline and breed in the numerous uninhabited islands that occur off the coast. The females pup in February and leave the rookeries during March/April. There are haul-outs all along the coastline at suitable locations. Grey seals are common in the area around Broadhaven Bay and are understood to pup in the inner part of Broadhaven Bay, towards Belmullet. There is also a significant population that uses the Inishkea group of islands to the west of the Mullet peninsula. Warner (1984) also identified Blacksod/Broadhaven Bay as one of the major breeding sites for grey seals in Ireland.

Otters

Otters (Lutra lutra) are common all around the Mayo coastline and feed in the inshore areas as well as the freshwater systems (lakes and rivers). There

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are records of otter holts in the vicinity of the Sruwaddacon, and Enterprise are liasing with Dúchas to ensure that the holts are protected as necessary during the construction works.

7.3.3 Landfall and Sruwaddacon

7.3.3.1 Benthic Communities

The shallow subtidal and intertidal habitats along the coast of north-west Mayo are characterised by either sediment shores, as in Broadhaven Bay and on both sides of the Mullet Peninsula, or by rocky subtidal and intertidal habitats. They are subject to a range of wave exposures, from extremely exposed on the outside of the Mullet Peninsula and north Mayo coast, to very sheltered in the bays and inlets.

Descriptions of the intertidal areas through which the proposed pipeline is routed are provided below. Figure 7.13 shows the locations from which the shoreline photographs were taken. Explanations of biotope classifications are provided in Appendix 7.1. Taxonomic results from the analysis of core samples taken by Aqua-Fact in 2000 are provided in Appendix 7.3, the locations of the coring sites are shown in Figure 7.5.

Figure 7.13: Locations and directions of shoreline photograph points Landfall Site

Shore of Landfall Site

At the landfall site, the shore is an extensive sandy beach backed by sand dunes (Plate 7.1). To the south, the shore is bound by a low rocky shore and to the east is the mouth of the Sruwaddacon.

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Plate 7.1: Landfall Site - Mobile sand in the upper mid-shore looking east towards the dune systems The initial coring survey carried out in July 2000 found that the upper shore of the landfall site consisted of medium to coarse sand, the mid-tide level consisted of medium sand and on the lower shore the sediment was coarser. Little evidence of macrofauna was found at all three levels.

Examination of the littoral habitats and communities during the survey carried out in June 2001 found that the upper shore supported a biotope of Talitrid amphipods in decomposing seaweed on the strand-line (LGS.Tal). Below this there was an extensive area of fine, mobile clean sand (IGS.Mob). No obvious infaunal species were recorded.

The midshore was characterised by a large raised area of cobbles, sand and occasional boulders. Most of the rocks were covered with ephemeral algae particularly Enteromorpha sp., Ectocarpus sp. and Porphyra sp. (Plate 7.2). Higher areas were more stable and possibly less influenced by sediment movement. They supported dense patches of Fucus vesiculosus. Many of the more sand influenced rocks supported an unidentified sand binding algae and there were many pools of standing water between the boulders. Here the alga Chorda filum was occasional, with chitons Lepidochitona cinereus and the sea anemone Actinia equina attached to the boulders.

At the lower shore side of the cobble area was a large pool formed at the junction of rock and sand. Boulders in the pools supported a range of species, including the barnacle Semibalanus balanoides, the tunicate Corella parallelogramma, the encrusting polychaete Pomatoceros triqueter and on their undersides, dense encrustations of bryozoans. The shore crab Carcinus maenas was common in the pool.

The lower shore consisted of extensive mobile fine sand, with no notable macrofaunal species. One sand eel Ammodytes sp. and one brown shrimp Crangon crangon were recorded.

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Plate 7.2: Landfall Site - Boulders and cobbles in the mid-shore with a dense coverage of ephemeral green algae Subsea Landfall Site

A subsea survey of the landfall site was conducted by Aqua-Fact in July 2000 and involved underwater photography of the seabed along a transect following the line of the landfall down to a depth of approximately 5 m. The seafloor in this area consisted of coarse rippled sand, with occasional shallow rocky outcrops (Plate 7.3). The most offshore section of the transect was dominated by sandy bottoms, with rocky outcrops becoming more frequent in the nearshore section.

Plate 7.3: Landfall Site – Seabed consisting of coarse rippled sand with occasional shallow rocky outcrops

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Landfall Summary

None of the species or biotopes recorded from the open coast landfall site were of specific nature conservation importance, or of commercial interest. The habitats recorded were extensive along the shore. The shore is very exposed to wave action, particularly from the north-west and the habitats recorded are typical of wave-exposed open coast areas. Many of the seaweeds growing on the boulder and cobble bank were ephemeral, quick growing species suggests that the rock is subject to high scour, or is periodically covered by sediment, preventing the establishment of longer growing species.

Downstream Crossing Point

West shore of Downstream Crossing Point:

The shore at this point was a fine muddy sand bay, between a rocky shore to the south and a raised cobble and boulder area to the north. A small stream ran down the middle of the site.

Two surveys have been carried out at the site, in July 2000 and June 2001. Examinations of the littoral habitats and communities showed that the extreme upper shore was dominated by grass and sea pink Armeria maritima. Talitrid amphipods occurred under drift seaweed. Below this the shore was characterised by the presence of the polychaete Hediste diversicolor. The sand had a narrow anoxic band just below the surface. This zone appeared to be restricted to the top of the shore.

The largest zone below this extended down most of the shore and was characterised by the cockle Cerastoderma edule that was common in the sand. Boulders buried in the sand supported sparse clumps of Fucus spiralis. Lugworm casts were also sparse throughout this zone.

The lower shore was anoxic sand with very dense lugworm casts (greater than 50 /m2) (Plate 7.4). Occasional clumps of Fucus vesiculosus occurred on boulders, with the shore crab Carcinus maenas, periwinkle Littorina mariae and areas of the brown seaweed Ectocarpus sp.

Just above the waterline, the sand mason worm Lanice conchilega occurred in areas with abundant polychaete tubes and the occasional Nephtys sp. and lugworm cast.

East shore of Downstream Crossing Point (Rossport):

The shore at this point consisted of angular cobbles, boulders and some bedrock and was backed by a steep bank leading up to farmland. Bedrock outcrops occur on the shore further into the bay with cobbles and pebbles dominant in the other direction.

The rocky substratum in this area precluded taking core samples during the July 2000 survey, therefore, a visual assessment of the shoreline was made as described below.

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The upper shore was dominated by Fucus spiralis and Pelvetia canaliculata.

Plate 7.4: Lower Crossing Point, West Shore - Dense Arenicola marina casts on the lower and midshore Common species found in the mid-shore area were flat winkle (Littorina littoralis), Ascophyllum nodosum, Polysiphonia lanosa (attached to the Ascophyllum), Gammarus spp., Fucus vesiculosus and the barnacle (Semibalanus balanoides). Less frequent species included Enteromorpha sp., Cladophora sp. and the common shore crab (Carcinus maenas). On the lower shore limpets (Patella vulgata) were common on the rocks, lugworm were recorded occasionally in small patches of fine sand on the lower shore and bootlace weed (Chorda filum) was common at low water.

Examination of the littoral habitats and communities during the survey carried out in June 2001 found that the upper shore was characterised by angular cobbles and boulders supporting grey lichens and Ramalina sp. The boulders also had grass between them, with sparse Armeria maritima. This band was very narrow (less than 0.5 m) and was assigned the biotope (LR.YG).

Below this was a narrow band of angular cobbles supporting the black lichen Verrucaria maura. Again grass and Armeria maritima occurred between the cobbles (biotope LR.Ver).

The cobbles below this were characterised by a band of Pelvetia canaliculata, approximately 2 m wide (biotope SLR.Pel). Between and under the boulders were sparse Littorina saxatilis, with small patches of Fucus spiralis. The boulders also supported the lichen Verrucaria maura and the red encrusting algae Hildenbrandia sp. Barnacles Chthamalus sp. and the shore crab Carcinus maenas were occasional under the larger boulders. Towards the bottom of the zone the seaweed Fucus spiralis was more common.

The dominant alga on the shore was Ascophyllum nodosum, which occurred in a dense band, approximately 5 m wide below the Pelvetia zone (biotope

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SLR.Asc) (Plate 7.5). The substratum was mixed bedrock outcrops, with angular boulders and patches of muddy, shelly sand. A range of species were recorded on and under the boulders, including the seaweeds Cladophora sp., Ectocarpus sp. Enteromorpha sp. and Hildenbrandia sp.; the molluscs Littorina mariae/obtusata, Patella vulgata, Nucella lapillus, a few mussels Mytilus edulis, and Gibbula sp.; and some amphipod crustaceans. The undersides of the boulders supported spirorbid worms, with the occasional sea anemone Actinia equina between them. The red algae Polysiphonia lanosa was common, growing on the Ascophyllum nodosum.

Plate 7.5: Lower Crossing Point, East Shore - Rocky shore characterised by the seaweed Ascophyllum nodosum At the bottom of the shore was a zone of sparse Fucus vesiculosus on angular rocks (biotope SLR.FvesX). Large patches of sand occurred between the boulders, particularly on the lower side of this zone. At the extreme bottom of this zone Fucus serratus was present. Many of the rocks supported the limpet Patella vulgata and the barnacle Semibalanus balanoides. The molluscs Nucella lapillus, Littorina littorea, Littorina saxatilis and Gibbula cineraria, were frequent with sparse mussels Mytilus edulis. The shore crab Carcinus maenas and amphipod crustaceans were occasional between and under the boulders, with the hydroid Obelia geniculata covering the undersides of some of the larger boulders. Patches of Verrucaria mucosa were present, with patches of the green seaweed Enteromorpha sp.

Channel at Downstream Crossing Point

From the west side of the channel the seabed was as bedrock and boulders leading down to a stony bottom (Plate 7.6), with patches of coarse sand, before extending down to coarse sand (Plate 7.7). Small rock outcrops occurred in the middle of the channel. Towards the east side, the sandy bottom gave way to a steep boulder outcrop leading to the eastern shore

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(Plate 7.8). At the base of this rock the seabed appeared to be scoured and characterised by coarse sediment.

Plate 7.6: Lower Crossing – Rocky boulder bottom on western side of crossing

Plate 7.7: Lower Crossing – Coarse sandy bottom in centre of channel The boulders on the west side of the channel supported dense red and brown seaweeds, particularly the bootlace weed Chorda filum. Mussels also occurred attached to the rock. Boulders and stones in the middle of the channel also supported red and brown seaweeds, although they are not as dense. Coralline algal crusts with the barnacle Balanus crenatus covered some cobbles. The sand in the centre of the channel appeared to be very coarse and mobile, with few obvious infaunal species.

Downstream Crossing Point Summary

None of the species or biotopes recorded from the downstream crossing point location were of nature conservation or commercial importance. The east shore was rocky and dominated by the alga Ascophyllum nodosum, which is characteristic of wave sheltered shores throughout Ireland and occurred along most of the eastern shoreline adjacent to the crossing point. The site was subject to strong tide streams, particularly the eastern shore. The west shore was predominantly sedimentary, supporting Arenicola marina and cockles in the midshore. The site also had a small stream running from the top of the shore.

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Plate 7.8: Lower Crossing - Steep rising boulder outcrop eastern side of crossing Upstream Crossing Point

The proposed crossing point at the upstream end of the Sruwaddacon has been changed since the end of 2000, in order to avoid an area of recently planted forestry. The shoreline survey which took place during 2000 took samples from the previously proposed crossing point, whilst in 2001 sediment cores were taken for biological analysis from the new alignment. The locations where cores were taken in 2001 are shown in Figure 7.14 (Figure 7.5 shows the locations of the sampling points from the summer 2000 survey).

North Shore of Upstream Crossing Point:

The shore at this point was backed by gently sloping agricultural land with grazing sheep.

Examination of the littoral habitats and communities during the survey carried out in June 2001 found that the top of the shore was composed of consolidated barren angular cobbles with a 'verge' of grass and an 8-10 m zone of Armeria maritima, which would probably be immersed during high water spring tides.

Below this zone was a 10-15 m wide band of angular cobbles with gravel and consolidated sand between them. The larger and more stable stones supported the brown algae Fucus vesiculosus (biotope SLR.Fves) (Plate 7.9). Towards the bottom of this zone, the dominant algae was sparse patches of Fucus ceranoides on cobbles and pebbles. The patches of muddy sandy gravel at this point were more extensive and anoxic, and supported sparse polychaete worms and Corophium sp.

The intertidal area of the north shore was much more extensive than the south and much sandier. Below the algal dominated zone of cobbles, the rest of the shore was compact sand and pebbles with patches of standing water. The sand supported polychaetes. At the bottom of the shore the sand was clean and relatively well sorted by strong tidal action and formed into large and small ripples. Little infauna was recorded.

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Plate 7.9: Upper Crossing Point – View of north shore showing consolidated sand and gravel with fucoid covered boulders on upper shore

Figure 7.14: Main biotopes and habitats recorded from the Upstream Crossing site and core sampling locations (1-5). (Explanation of biotope classifications provided in Appendix 7.1) In addition to the visual survey, core samples were taken from the upper mid shore and lower mid shore and the low shore (as shown in Figure 7.5 for 2001 core sampling locations). The midshore samples were characterised by the amphipod crustacean Corophium sp. and polychaetes. The low shore sample was taken from coarse mobile sand and contained no infaunal species (see Table 7.7).

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Table 7.7: The species recorded and their abundance (m-2), from the core samples taken at the Upstream Crossing Point Site 1 2 3 4 5 Corophium sp. 1356 377 - 603 301 Mysidae indet. 226 75 - - Hediste diversicolor 75 1281 - 527 75 Oligochaeta indet. 226 75 - - Polychaeta indet. 75 - - Nereidae indet. Sp. A 377 - - 150 - Nereidae indet. Sp. B 452 - - - South Shore of Upstream Crossing Point:

The shore at this point was backed by dense forestry on top of a 2-3 m 'cliff' of peat. At the base of the cliff was a `terrace’ of grass with thrift Armeria maritima, which was probably inundated by high spring tides. The base of the peat cliff had been eroded and drift seaweeds were present. Towards the east of the crossing point there was a small freshwater input from the forestry. Enteromorpha sp. occurred on the lower part of the peat. At this point the grass terrace was reduced considerably.

Examination of the littoral habitats and communities during the survey carried out in June 2001 found that the upper midshore comprised consolidated cobbles and pebbles on muddy sand, with the algae Fucus vesiculosus and Fucus ceranoides (sparse) on mixed substrata (biotope SLR.FvesX) (Plate 7.10). Fucoids were more dense at the top of the shore and became more sparse at the lower end of the zone, where the cobbles gave way to mud. The zone of cobbles was approximately 15 m wide. Between the stones and under the weeds the amphipod crustacean Gammarus sp. and the shore crab Carcinus maenas were present. Polychaetes, particularly Hediste diversicolor, occurred in the mud with one eel Anguilla anguilla recorded under a boulder. The red algae Hildenbrandia sp. occurred on some of the larger cobbles with Ascophyllum nodosum also occasional.

At the extreme bottom of the zone of cobbles was a narrow band of the seaweed Fucus ceranoides (biotope SLR.FcerX).

The lower shore consisted of fine sandy anoxic mud, with numerous polychaetes (possibly Hediste diversicolor), and some crustacean amphipods Corophium sp. The anoxic mud overlaid a coarse gravel layer.

In addition to the visual survey, core samples were taken from the mid and low shores (as shown in Figure 7.14 for core sampling locations). It was not possible to take cores from the upper shore, as it was too rocky. The core samples were also characterised by the crustacean Corophium sp. and polychaetes, (see Table 7.7).

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Plate 7.10: Upper Crossing Point: fucoid covered boulders on upper shore River Channel at Upstream Crossing Point

The channel at this crossing point appeared to be mobile sand and mud, with some patches of peat eroded by the strong tidal movement. The banks of the channel were steep and sandy and supported abundant Crangon crangon and mysid crustaceans.

Upstream Crossing Point Summary

None of the species or biotopes recorded from this upper crossing point location are of particular nature conservation or commercial importance. The low salinity tolerant species Fucus ceranoides occurred lower down the shore, suggesting that the bay at this location is very much estuarine. These species were found only where rocks and consolidated substratum were available for their attachment. The lower shore on both sides of the river was predominantly sedimentary. The south shore was muddier, which is probably due to the bend in the river causing fine sediments to be deposited on the shore. The north bank occurred on the inside bend of the river, where higher flows resulted in coarser mobile sediments. The habitats recorded at the crossing location occurred along much of the shoreline in the upper bay and none were restricted to the crossing location.

During the 2000 and 2001 surveys, no species were found which are specifically listed under the Habitats Directive (92/43/EEC). None of the species recorded during the surveys were rare or unusual and all had been recorded from other locations in Ireland.

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7.3.3.2 Fisheries

Pelagic Fisheries

Anadromous species, such as the Atlantic salmon (Salmo salar) and sea trout (Salmo trutta), migrate through the Glenamoy and Muingnabo Rivers; the period of highest spawning migrations is during the late spring and summer months. It is at this time that salmon, returning to their native river to spawn, would pass through the Sruwaddacon. It is also the period when smolts would move down the river to enter the sea. Due to the water depths of the river at the landfall site, it is unlikely that any fish would remain in that precise location for any length of time. Small numbers of eels (Anguilla anguilla) are also known to migrate through the Glenamoy and Muingnabo rivers. Several migratory fish species are protected under Irish and European legislation, these species and their protection status are shown in Table 7.8. Of these species, only the Atlantic salmon have been recorded from the Glenamoy and Muingnabo rivers.

Table 7.8: The protection status of a number of migratory fish species Common Species name Irish Red Habitats Berne name data book Directive Convention Allis shad Alosa alosa E II III Twaite shad Alosa fallax V II, V III River lamprey Lampetra fluviatilis I II, V III Smelt Osmerus eperlanus V - - Sea lamprey Petromyzon marinus I II III Atlantic Salmo salar II II, V III salmon Irish Red Data Book: E – endangered, V - vulnerable, I – indeterminate, II – internationally important Habitats Directive: II – Annex II animal and plant species of community interest whose conservation requires the designation of special areas of conservation IV – Annex IV animal and plant species of community interest in need of strict protection V - animal and plant species of community interest whose taking in the wild and exploitation may be subject to management measures Berne Convention: III protected fauna species

Aquaculture

One licensed oyster culture facility operates in the Sruwaddacon and this is located in the mid-reaches close to the village of Pollatomish, the location of the site is indicated in Figure 7.12. It is understood that production of oysters from this site is low.

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7.3.3.3 Seabirds

Little terns (Sterna albifrons) have been reported to breed over the last number of years in the area north of where the pipeline comes ashore. Although accurate counts are not available for last year, it is possible to say that the numbers of breeding pairs are less than ten. This is an endangered Annex I species (under the EU Birds Directive) and is protected. The proposed landfall is 500 m south of the little tern breeding area. However, these two factors indicate that the construction activity will need to be carefully planned to ensure that the little tern population is not disturbed.

In addition to the tern colony on Inishderry in the south-western part of Broadhaven Bay, this species has been nesting on the shingle/sand bars at Pollatomish (opposite Rossport) intermittently for fifteen years. The nest locations have been approximately 0.5 km distant - at the nearest point - from the proposed pipeline route. Numbers observed were as follows (data from BirdWatch Ireland):

• 1984 – 6 pairs nesting on the shingle/sand bank; • 1995 – not recorded during the All-Tern Survey; • 1999 – estimated 2 breeding pairs; and • 2000 – no definite information but “probably” there.

With regard to Sruwaddacon Bay SPA, until recently limited data have been collected regarding the bird species that occur on the site. As recently as last year there was only one count (IWeBS –March 1999 – Table 7.9) of wintering species in the area. The count centred on the area near the pier at Pollatomish. The most significant species recorded on this count was the pale bellied Brent Goose (Branta bernicula hrota), which is a listed Annex II species. The other species recorded include Dunlin (Calidris alpina) and Ringed Plover (Charadrius hiaticula). More detailed monthly counts were initiated in the winter of 2000/2001 by Dúchas. The data available from these counts is provided in Table 7.10.

Table 7.9: Sruwaddacon Bay – winter count 1999 Species Count Cormorant 1 Grey Heron 1 Light-bellied Brent Goose 116 Oystercatcher 15 Ringed Plover 3 Dunlin 16 Bar-tailed Godwit 35 Curlew 20 Redshank 5 Greenshank 3 Black-headed Gull 53 Common Gull 13 Lesser Black-backed Gull 1 Herring Gull 2

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Table 7.10: Sruwaddacon Bay IWeBS counts Sept.2000 – Feb 2001 (courtesy of Dúchas) Species Sept. Oct. Nov. Dec. Jan. Feb. Spp. Total Great Northern Diver 2 2 Cormorant 19 13 15 16 3 15 81 Curlew 135 112 30 140 52 50 519 Oystercatcher 55 56 22 64 29 47 273 Great black backed gull 2 2 4 6 5 9 28 Herring gull 19 8 4 3 9 5 48 Common gull 23 15 12 3 41 24 118 Black headed gull 93 30 2 4 1 130 Brent Goose 43 160 203 Sanderling 4 14 18 Bar-tailed godwit 12 16 42 24 25 4 123 Grey Plover 21 21 Ringed Plover 135 114 56 40 77 25 447 Wigeon 8 8 Mallard 4 9 7 15 35 Teal 2 2 Red breasted merganser 3 1 6 13 9 32 Heron 11 1 5 7 1 25 Redshank 19 33 12 4 21 45 134 Greenshank 19 4 6 12 7 14 62 Dunlin 37 16 333 72 49 108 615 Knot 2 3 5 Unidentified 15 15 Raptors (merlin) 1 1

Monthly Total 583 426 571 455 348 546

7.3.4 Designated Conservation Areas along the Subsea Pipeline Route

Dúchas, the government agency in charge of conservation of flora and fauna and habitats, has drawn up a list of candidate Special Areas of Conservation (SACs) and Special Protection Areas (SPAs) on the coast of north-west Mayo. Broadhaven Bay cSAC and the Glenamoy Bog Complex SAC (including the Sruwaddacon SPA) are within the vicinity of the proposed project, and their locations are shown in Figure 7.15. Blacksod Bay and Broadhaven is also a Ramsar site (No. 844) designated in 1995, this Ramsar site has the same boundaries as the Blacksod and Broadhaven SPA

7.3.4.1 Special Areas of Conservation

SACs are sites of European Community importance, which means they contribute significantly to the maintenance of a natural habitat type listed in Annex I of the Habitat Directive, or a species listed in Annex II. Once a site has been designated, the Member State shall establish the necessary measures to conserve the habitat within six years. SPAs are special protection areas for birds, which are designated in accordance with the Birds Directive. Once designated, measures will be taken to preserve, maintain and restore biodiversity and an area necessary for birds listed in Annex I of the Directive.

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Table 7.11 provides a list of the names of the SACs numbered above Figure 7.15: Nature Conservation Sites around Broadhaven Bay and the Mullet peninsula

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Table 7.11: Site names of Special Areas of Conservation (SAC) and candidate SACs shown in Figure 7.15 SITE CODE SITE NAME 000470 Mullet/Blacksod bay Complex 000472 Broadhaven Bay 000476 Carrowmore Lake Complex 000485 Corraun Plateau 000495 Dullivan Islands 000500 Glenamoy Bog Complex 000507 Inishkea Islands 000522 Lough Gall Bog 000534 Owenduff/Nephin Complex 000542 Slieve Fyagh Bog 001482 Clew bay Complex 001497 Doogort Machair/Lough Doo 001501 Erris Head 001513 Keel Machair/Menaun Cliffs 001922 Bellacorrick Bog complex 001955 Croaghaun/Slievemore 002243 Clare Island Cliffs 002268 Achill Head Broadhaven Bay SAC

Broadhaven Bay candidate SAC contains excellent examples of four habitats listed on Annex I of the EU Habitats Directive, namely Atlantic saltmarsh, tidal mudflats, reefs and large shallow bay. The shoreline comprises mostly shingle beaches and sandy beaches, as well as marginal habitats, such as cutaway bog, heathland, dune grassland, machair, wet grassland, tidal rivers and dry pasture, which is used for grazing. There are several extensive areas of intact saltmarsh, with Thrift (Armeria maritima), Saltmarsh Rush (Juncus gerardii), Buck's-horn Plantain (Plantago coronopus), Sea Arrowgrass (Triglochin maritima), Common Scurvygrass (Cochlearia officinalis) and Common Saltmarsh-grass (Puccinellia maritima). Parts of the saltmarsh are heavily grazed.

In addition to the above, Broadhaven Bay supports an internationally important number of brent geese (average peak 292, 1983/84-86/87), as well as regionally important populations of ringed plover (234), golden plover (103), dunlin (271), bar-tailed godwit (85), curlew (186) and redshank (80) (all figures are average peaks for the period 1984/85-1986/87).

Other sites of environmental importance in, or in the vicinity of Broadhaven Bay include Erris Head, the Stags of Broadhaven and Eagle Island (as shown in Figure 7.15.

Erris Head is an extensive stretch of rocky sea cliffs on the Mullet peninsula, which has been identified as being of ornithological importance. In addition, the steep to vertical rugged cliffs along this section of coastline contain other habitats of interest, including blanket bog and wet grassland on peaty and mineral soils.

The Stags of Broadhaven, to the north-east of Broadhaven Bay are a group of four precipitous rocky islets totalling 4 ha in area, which rise to a height

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of almost 100 m. They are located about 2 km north of Benwee Head. The islets are of ornithological interest, although their relative inaccessibility has made population counts difficult. The Islands are the only known breeding site for Leach’s Storm-petrel (an EU Bird Directive Annex 1 species) in Ireland.

Eagle Island is a small marine island situated about 1 km north-west of Doonamo Point on the Mullet Peninsula. The site holds breeding colonies of common gull (12 pairs in 1969), and herring gull.

A full description of the above sites are provided in Appendix 7.4.

Glenamoy Bog Complex SAC

The Glenamoy Bog Complex SAC (candidate SAC 500) is the only designated area through which the onshore pipeline passes. This is a very large site encompassing a variety of habitat types and is described in Appendix 7.4.

Coastal areas include the sea cliffs of the north Mayo Coast (important for breeding seabirds), dune and machair (associated with the mouth of Sruwaddacon Bay – predominantly the locality at Garter Hill). Much of the machair is now very degraded mainly as a result of overgrazing by sheep and cattle. The sandy coastal areas are highly mobile in the strong prevailing westerly winds.

The main feature of this SAC is the oceanic lowland blanket bog, of international importance and an Annex I habitat (EU Habitats Directive). Much of this bog is still prime habitat and is well documented, having been the subject of blanket bog research both nationally and internationally for over thirty years.

Large areas of this complex site are intact and of great ecological value. However, parts of this SAC have been subject to damaging land-use practices over a long period of time. These include:

• grazing by sheep and cattle which has resulted in erosion on parts of the bog and in the coastal grassland areas – including the Garter Hill machair site; and • peat cutting – until recently this was done mainly by hand. In recent years, mechanical means have also been used more frequently (e.g. sausage-machines). Peat cutting is widespread and is usually confined to areas beside roads, tracks and habitation.

The Glenamoy Bog complex SAC also contains the Sruwaddacon Bay SPA.

7.3.4.2 Special Protection Areas (SPA)

Sruwaddacon Bay SPA

Sruwaddacon Bay SPA is a shallow tidal inlet off Broadhaven Bay (candidate SAC 472) and its estuarine habitats are important feeding grounds for over-wintering wildfowl. There is currently little information available on baseline conditions in Sruwaddacon Bay. However regular

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winter wildfowl counts by Dúchas commenced in 2000 (see Table 7.9). Mapping of the intertidal mud and sand flats was also carried out by the statutory authority over the winter 2000 – 2001. In addition to its special importance for its wintering wildfowl populations, the Bay forms an integral part of the Glenamoy River salmonid fishery.

7.3.4.3 Ramsar Sites

Blacksod Bay and Broadhaven has been designated as a Ramsar site under the Ramsar Convention criteria 2c, 3b and 3c. …

”the site is important for a range of maritime and coastal habitats. The area holds internationally important numbers of Brent geese Branta bernicula and ringed plover Charadrius hiaticula. Blacksod Bay….”.

The full citation for the site is provided in Appendix 7.4. The site boundaries are the same as those for the Blacksod and Broadhaven Bay SPA shown in Figure 7.15 as the shaded areas of SACs 470 and 472.

The Ramsar Protocol and amendments state that, in the event that a Ramsar site is deleted or restricted, the signatory country should create additional reserves for water fowl. In the case of the Corrib Project, there will be no deletion or restriction of land within the Ramsar site. Therefore there is no obligation on Enterprise to replace lost land.

7.4 Characteristics of the Proposed Development

Past exploration activity undertaken in the vicinity of the Corrib Field includes two seismic surveys undertaken in 1994 and 1997 and an exploratory and appraisal drilling programme from 1996 to 2001. In 1996 the exploration well 18/20-1 was drilled and subsequently abandoned. Between 1998 and 2001 five appraisal wells (18/20-2z, 18/25-1, 18/20-3, 18/20-4 and 18/25-3) were drilled and suspended.

Future work will include the drilling and completion of three wells. The five existing appraisal wells will be re-entered and completed (see Section 3). A 20” gas pipeline will be constructed from the Corrib Field to the onshore Terminal. Well operations will be controlled from the terminal by an integrated electro-hydraulic control umbilical, which will lie alongside the export pipeline.

In addition to the above, a water discharge pipe will be laid in Broadhaven Bay from the Terminal site. This will be installed at the same time and in the same trench as the gas pipeline. It is likely that the discharge pipeline will be “piggy-backed” onto the larger gas pipe, in order to assist in the construction.

7.5 Potential Impacts of the Proposed Development

The potential impacts of the proposed development are sub-divided into those associated with the offshore, nearshore and landfall operations, as outlined below.

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7.5.1 Potential Offshore Impacts of the Proposed Development

Offshore impacts are those associated with the drilling and field facilities within the Corrib Field and the offshore gas export pipeline (and umbilical) from the Corrib Field to waters outside of Broadhaven Bay.

7.5.1.1 Potential Drilling Impacts

During Installation

During site set-up works there is the potential for physical disturbance to benthic faunal communities from rig positioning, running and setting of anchors and pulling of anchors. In addition, there will be localised increased water column turbidity near the seafloor, which potentially affect benthic filter feeders and demersal fish species. Filter feeders are vulnerable to smothering from increased sediment levels, and fish gills are susceptible to abrasion by excessive exposure to elevated suspended solid levels. However, fish are generally highly mobile and will avoid unfavourable conditions. In addition, there is the potential for the release of sediment-bound pollutants in a bioavailable form into the water column.

Impacts on flora are not anticipated during rig positioning, as water depths in the area will generally preclude the growth of benthic flora.

Following positioning, the semi-submersible drilling rig will take on ballast water. A potential impact from this activity is fish being transported into the ballast tanks.

During Operation

During operation of the drilling rig, impacts to fauna and flora, which could result, are discussed below.

The discharge of mud and cuttings has the potential to result in localised smothering of benthic communities around the well site. Filter or suspension feeders are likely to be most sensitive to the effects. The impact of mud and cuttings discharge is dependent on the type of mud used and the volume discharged. Cuttings coated with oil based muds pose a higher impact potential, whilst cuttings from the water-based mud (WBM) sections have a lower impact potential. During the drilling of future wells in the Corrib Field there will be no discharge of oil based muds.

In addition to the impacts that result directly from the physical nature of the cuttings, it is possible that the constituent chemicals of the drilling fluids have some degree of toxic impact on marine organisms. Of these, it is the discharge of heavy metals, as contaminants on the weighting agent barite, along with drilling muds, that have the potential to affect to marine life.

The discharge of cement during cementing of the casings can have a localised short term toxic effect on benthos, plankton and fish due to its high pH value. It can also have a localised smothering effect on the seabed.

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Rig wash water is discharged via the cuttings chute. It includes a detergent used to wash down certain parts of the drilling rig. The detergent (BW Envirowash, a HOCNF category D product has been used to date in the Corrib Field) is diluted before use. Plankton and fish inhabiting the upper water column are potentially most vulnerable to toxicity effects. The high dilution available in the sea reduces any impacts to a negligible level.

Drainage water, waste water (including black (sewage) and grey (washroom) water) and macerated food waste, are discharged to sea. Plankton and fish inhabiting the upper water column are potentially the most vulnerable to increased biological oxygen demand (BOD) and toxicity effects. Potential impacts from this discharge are negligible because of the rapid dilution once the effluent enters the sea.

The discharge of blow-out preventer (BOP) fluid, as a result of routine testing, has the potential to exhibit toxic effects on benthos and demersal fish. However, impacts would be negligible from this discharge, because the BOP fluid is glycol based (HOCNF category E), low volumes are discharged and the material that is discharged will quickly dilute.

Noise

The impact of the noise generated by the Corrib drilling operations will be dependent upon a number of factors including:

• the characteristics of the noise signal, especially the sound intensity level and frequency spectrum of the sound; and • the type of marine fauna, especially fish and marine mammals, present within hearing range and its sensitivity to underwater noise. Characteristics of Drilling Noise From available data, the noise generated by a MODU is typically at an intensity level of 154 dB re 1µPa at 1m, and within the frequency range of 10-4000 Hz. Section 11 lists other sources of underwater noise and discusses in detail the tolerance of marine organisms to them. The data indicates that source intensity levels generated by drilling are comparable with those from shipping and cetaceans, and are lower than seismic noise, but greater than the noise from wind and rain. Drilling noise is predominantly in the low frequency range of 10-4000 Hz, although the strongest tones are at frequencies of around 30-70 Hz.

Underwater noise generation will be greatest during periods of drilling activity, with principal sources of noise being power generation exhausts, rotational drill equipment, support vessel movement and flaring.

In the case of cetaceans, the data available on their hearing capabilities indicates that most baleen whales can detect low-frequency sounds (primarily below 1 kHz and in some cases down to 20 Hz). These overlap with the dominant frequencies associated with drilling noise. Small toothed whales tend to have poor hearing below 1 kHz and are better at detecting higher frequencies in the range 20-100 kHz.

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Table 7.12 presents a comparison of sounds produced by the typical Baleen and Toothed whale species in the eastern Atlantic area.

Table 7.12 Comparison of sounds produced by main baleen and toothed whale species in the Eastern Atlantic area with drilling noise (Richardson et al., 1995) Species Dominant Frequency Source Level Range (Hz) (dB re 1 µPa at 1m) Drilling (Semi-sub MODU) Drilling (Semi-Sub) 7-4000 Up to 154 Baleen Whales Humpback whale 25-360 144-192 Fin whale 20-250 155-186 Minke whale 60-140 151-175 Toothed Whales Sperm whale 200-16000 160-180 Killer whale 1000-25000 160-180 Long-finned pilot whale 1600-6700 180 Atlantic white-sided dolphin 6000-15000 - Underwater sound at high intensity (amplitude) can, therefore, at the right frequency, have the potential to affect the behaviour, or even damage the hearing of animals (e.g. plankton, fish or marine mammals) coming in close proximity to the sound source. It may also have the potential to disturb or confuse marine mammals, for example, through changes in swimming and breathing patterns, masking of communication between animals and indirectly through possible deterrence to breeding and feeding.

Noise impacts from helicopters are discussed in Section 11. It has been noted that cetaceans may dive or turn away during overflights. As the noise levels from helicopters are transient, no long-term impacts are expected (Richardson et al., 1995).

Noise impacts are discussed in more detail in Section 11.

During Decommissioning

Following drilling, the wells will be temporarily suspended and the semi- submersible rig will be floated off site. Prior to floating off, ballast water will be discharged into the marine environment. This ballast water will not contain any contaminants therefore impacts from this operation are not anticipated.

7.5.1.2 Potential Field Facilities Impacts

During Installation

The following operations have the potential to result in seabed disturbance during installation of the field facilities:

• well tie-in and installation of flowlines; • seabed preparation for manifold and other facilities (levelling and piling,

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installation of mud mat etc); and • recovery of debris and temporary construction work items.

The subsequent increased sediment levels in the water column have the potential to cause smothering of benthic fauna and damage to demersal fish gills. However, fish are generally highly mobile and will avoid unfavourable conditions. In addition, there is the potential for the release of sediment bound pollutants in a bioavailable form into the water column.

Typical noise levels generated by marine vessels working in the Field will be in the order of 170-180 dB re 1 µPa (Richardson et al., 1995). This noise will be generated at the sea surface, and is expected to have negligible effect upon the cetaceans and fish in the area. There are likely to be stronger tones from the use of bowthrusters by vessels maintaining position without anchors. The frequencies are probably at the lower end of toothed whale hearing thresholds and therefore sensitivity to this source will be lower.

Discharges from the construction vessels, such as black and grey water and galley waste, will have similar potential impacts to those discussed for the drilling rig.

Vessels will only be present within the field and pipelay areas for short periods of time during which the leaching of any tri-butyltin (TBT) in their antifouling will have negligible impact.

During Operation

During normal operation of the subsea facilities, there will be small discharges of hydraulic fluid (glycol/water mix) from valves and connectors. This mix is a HOCNF category E chemical and therefore, the potential to have a localised low toxicity effect on benthos, plankton and fish, will be negligible because of the low volumes intermittently discharged and the high dilution of the glycol immediately upon release.

During Decommissioning

Decommissioning of the field facilities will involve removal of all structures to depths of more than 3 m below the seabed, in compliance with the OSPAR Decision 98/3. Removal could re-suspend sediments, consequently increasing water turbidity and causing smothering of benthic communities and damage to fish gills. However, fish are generally highly mobile and will avoid unfavourable conditions.

In addition, there is the potential for the disturbance of cuttings accumulations releasing chemicals into the water column. Impacts from this disturbance are anticipated to be negligible, as decommissioning will take place after approximately 15-20 years of operation. By this stage, any remaining cuttings will be in very shallow accumulations and any toxic chemicals will have degraded and leached from them.

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7.5.1.3 Potential Pipeline and Umbilical Impacts

During Installation

In the offshore section of the route the pipeline will be laid on the seabed, while the umbilical will be buried using a remote trencher. These operations have the potential to result in seabed disturbance from the following: laying of pipe on the seabed; trenching in of the umbilicals; dredging; and rock placement in limited areas to prevent spans.

The subsequent increased sediment levels in the water column have the potential to cause smothering of benthic fauna and damage to demersal fish gills. However, fish are generally highly mobile and will avoid unfavourable conditions.

Rock placement, as well as causing increased turbidity in the water column, has the potential to introduce rock to sandy sediments, with loss of habitat type over a localised area and introduction of new rocky substrate for colonisation by benthic communities.

During Testing and Commissioning

During hydrotesting and commissioning of the pipeline, water will be abstracted from offshore and discharged back into the marine environment in the Corrib Field. This has the potential to introduce corrosion inhibitors and biocides, injected into the hydrotest water, into the marine environment, with the potential for toxic effects on plankton, benthos and fish. This discharge could provide a minor impact in the Corrib Field, due to the relatively high volume of the discharge. Dilution and dispersion will rapidly reduce the toxicity of the discharge. Plankton are extremely unlikely to be affected, as the discharge will be made close to the seabed.

During Operation

During operation of the pipeline there is the potential for leaching of trace metals from the sacrificial anodes placed throughout the length of the pipeline. The potential impact on benthos, plankton and fish will be negligible because of the small volumes involved, see also Section 9.

During Decommissioning

During decommissioning of the pipeline and umbilical, the pipeline will probably be capped, made inert by cleaning then filling with water, and left in place on the seabed, in accordance with current industry practice. The umbilicals will also be drained and left in place. Potential impacts associated with this operation are not anticipated.

7.5.2 Potential Nearshore Impacts of the Proposed Development

The potential impacts of the nearshore development are those associated with the gas pipeline and the discharge of water within Broadhaven Bay.

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7.5.2.1 Potential Export Pipeline and Umbilical Impacts

During Installation

The burial method for both the pipeline and umbilical will be either by jetting the sediment away from beneath it. These operations have the potential to result in seabed disturbance and subsequent smothering of the benthos, which will result in short-term alteration of the immediate habitat. The impacts to the seabed from pipeline installation are considered to be minor because of the relatively small area of seabed which will be affected, and because over time the sediment profiles will return to those present before the pipeline was laid.

The depth of sand in the bay is shallow and rock has been encountered within the design trench depth. Blasting over a short section within the nearshore area will therefore be required. Blasting has the potential to disturb larger areas of seabed, causing increased turbidity, sediment disturbance and suspension, with the potential for lethal/sub-lethal effects on benthos. Localised areas of benthic communities and filter-feeding species, such as shellfish, could be affected through smothering. In addition, underwater blasting, without mitigation, has the potential to cause severe impacts to many forms of marine life, including cetaceans. Noise disturbance from subsea construction work within Broadhaven Bay also has the potential to impact upon the cetacean community in this area.

Data on underwater blasting suggest that lower underwater pressures can result in more serious impacts than those required to cause damage in air (Myrick et al., 1989).

There are spawning grounds for herring along the Mayo coastline, these are unlikely to be affected by installation of the pipeline or umbilical because of the timing of the operations. The spawning season for herring is in autumn, while the pipeline and umbilical will be laid earlier in the year. The Ross Bay nursery area is too far away from the installation operations to be affected.

During Operation and Decommissioning

These are the same as those for the gas pipeline in the offshore zone see (Section 7.5.1.3).

7.5.2.2 Potential Impacts of the Water Discharge Pipe

During Installation

Potential impacts during installation will be exactly the same as those associated with installation of the pipeline (see Section 7.5.2.1), as the water discharge pipe will be strapped to the gas pipeline.

During Operation

During operation, treated effluent from the Terminal will be discharged into Broadhaven Bay through the outfall pipe. This treated effluent will comprise

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treated water from the reservoir mixed with treated rainwater run-off from the Terminal (see Section 9). If untreated, this effluent at elevated concentrations has the potential to affect plankton, fish and benthos, with filter feeders particularly susceptible.

Trace metals entering the marine environment can be accumulated by marine organisms, and depending upon the concentrations involved, can have adverse, and in some cases lethal impacts. To determine the possibility of such impacts occurring, it is necessary to understand the possible fate of metals entering the sea, and the potential for accumulation of contaminants over time, in specific reservoirs.

It is widely documented that mercury is of significance in relation to accumulation in both fish and invertebrates. Selenium is both essential in nature for some cell functions, and highly toxic at elevated concentrations. Arsenic is generally not problematic in marine waters (except at exceptionally high concentrations), due to its tendency to accumulate in relatively non-toxic organic forms in marine organisms.

Some of the other non-essential elements may be of concern, particularly cadmium. It is known that the concentrations of cadmium assimilated by the human populations of many western and other countries are close to the threshold at which observable effects occur to humans. Sometimes this level is exceeded. This has driven concerns over the accumulation of cadmium in the environment as a whole, and its inclusion on the so-called Black List (List I) of the European Union and on many other similar lists of contaminants of concern in aquatic environments.

Silver can also be of concern in such environments, although much less is known about silver in coastal waters (e.g. compared to elements such as mercury or cadmium). Nevertheless, silver is documented to be of significant toxicity to phytoplankton, and it has been shown to be associated with municipal/industrial waste water outfalls.

The other essential trace elements (copper and zinc) are metabolically regulated in the muscle of fish, and are generally not problematic in situations such as the discharge into Broadhaven Bay (Phillips, 2001).

Discharge of Methanol and Total Organic Carbon

Methanol will be used in the exploitation of the gas from the Corrib Field. It is likely that a low concentration of this chemical will also be discharged with the water. It is anticipated that an annual maximum of 0.58 tonnes of methanol will be discharged.

Methanol is classified by the Oslo and Paris Commission (OSPAR) as a substance that poses little or no risk to the environment (PLONOR). This is effectively the most benign classification for any chemical used and discharged in the oil and gas industry.

Organic discharges may result from the contaminated rainwater runoff from the Terminal site. It is estimated that the maximum annual discharge of total organic carbon (TOC) from the Terminal will be approximately 3

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tonnes. This equates to approximately 8.2 kg per day. If untreated, this runoff could impact the marine life of the bay, as it is known that such compounds have the potential to enrich.

The treatment of this discharge is discussed in Section 9.

Trace organic contaminants can be present in waste waters at concentrations of environmental concern. Levels of benzene, toluene, ethylbenzene and xylene (BTEX) in the discharge, will be at a concentration of 0.01mg/l or below. For comparative purposes, concentrations of BTEX in produced water from 17 installations in the Norwegian sector of the North sea ranged from 1 – 67 mg/l (OLF, 1998).

Negligible impacts are expected from trace organic compounds discharged into Broadhaven Bay.

Physical Impacts

The discharge is likely to be intermittent to provide best dispersion, mainly over the ebb tide, except during periods of extremely heavy rain. The speed of the discharge has the potential to push away small organisms which happened to be in the water column in the vicinity of the pipeline when the discharge is occurring. The physical influence of the discharge stream will decrease quickly and organisms that are a few metres away are unlikely to experience any abnormal effects.

During Decommissioning

These are the same as those for decommissioning of the gas pipeline; see Section 7.5.1.3. The diffuser will be removed from the seabed at the end of the discharge pipeline.

7.5.3 Potential Impacts of the Proposed Development at the Landfall and Sruwaddacon Crossings

Potential impacts in this section are those associated with the gas pipeline landfall and Sruwaddacon crossing points.

7.5.3.1 Potential Pipeline and Umbilical Impacts

During Installation

Construction of the landfall and the Sruwaddacon Bay crossings has the potential to cause habitat disturbance due to noise, excavation activities, increased traffic loading and from both aqueous and non-aqueous emissions. Particular areas of sensitivity include the little tern colony to the north of the landfall and the corncrakes in the fields bordering the Sruwaddacon.

During the landfall works, some noise will be generated from the laybarge during the pulling and pipeline lowering operations, which has the potential to disturb cetaceans in the immediate vicinity. There is potential for accidental release of contaminants and litter from the site.

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The two crossing points of the Sruwaddacon will be open-cut, there is therefore the potential for sediment release into the watercourse, with subsequent smothering of algae and spawning areas and damage to fish gills. However, fish are generally highly mobile and will avoid unfavourable conditions. Habitats and species could be smothered by spoil from the trenches, however, this is likely to be a short-term impact. Similarly, trampling will occur on the shore by construction personnel and plant.

During Operation and Decommissioning

There are no anticipated impacts from the operation of the pipelines and umbilical at the landfall and the Sruwaddacon crossings. In the event that the decommissioning option of removing the pipeline from these areas is selected, there will be some disruption caused by plant working in the intertidal and subtidal areas. The final choice of decommissioning option will be made after a study has considered the environmental implications of all options.

7.6 Do-Nothing Scenario

If the development did not proceed, the offshore, nearshore and landfall habitats and species would not be affected by the proposed drilling, gas pipeline and produced water discharge pipe.

7.7 Mitigation Measures

7.7.1 Offshore Mitigation Measures

Offshore mitigation measures have been developed to prevent, control and minimise potential impacts from drilling activities within the Corrib Field and offshore pipeline construction from the Corrib Field to waters outside of Broadhaven Bay.

7.7.1.1 Drilling Mitigation Measures

During Installation

During rig positioning and running and setting of anchors, disturbance to the marine environment will be minimised by limiting the footprint of the activities.

During taking on of ballast water, strainers will be fitted onto the ballast tanks to prevent entry of fish.

During Operation

The following mitigation measures will be employed during drilling:

• impacts associated with the discharge of water-based mud (WBM) and cuttings during drilling will be minimised by using a WBM formulated

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with environmentally benign chemicals (PLONOR or HOCNF category E – see Appendix 4.1), with low environmental toxicity, high biodegradability and low bioaccumulation potential. The barite used will only have trace levels of heavy metals (in particular Cd < 0.5 mg/kg and Hg < 0.01 mg/kg). The majority of the cadmium and mercury will be in an inorganic form, associated with the barite, and will be bound into the sediment following release where they will not be bioavailable;

• slimhole well design will be used which reduces the amount of drilling fluids required;

• impacts associated with the use of low toxicity oil-based mud (LTOBM), during drilling of the lower hole sections, will be mitigated by returning the cuttings to shore for recycling and safe disposal;

• impacts associated with cementing of the drill casing will be minimised by using a predetermined casing programme, with cement volume requirements estimated on a section by section basis, to reduce the volume of excess cement discharged;

• impacts associated with the routine discharge of rig wash waters will be mitigated through the use of a rig wash chemical that is of low toxicity and biodegradable; and

• discharges of drainage, waste water (including black water, grey water and galley wastes) will be minimised through a number of mitigation measures, as follows:

• oily water effluent will be treated to achieve a maximum of 15 ppm oil in water content. Continuous automatic sampling of oily water effluent will be undertaken and linked to system to automatically divert off-specification effluent back to the oily bilge tank system. High level alarms will be fitted to oily bilge tank units to prevent accidental discharge; • all spaces on board will be categorised according to the likely contamination status of the drainage and separate closed and open drainage systems will be operated; • all storage tanks and machinery spaces will be bunded and routed to the closed drainage system; and • operation of vessels will be carried out in accordance with Annex V of MARPOL 73/78. The BOD of the sewage and galley waste discharges will be reduced by a treatment process to 50 mg/l. The treatment process will involve preliminary maceration of the incoming sewage, followed by biological treatment, and subsequent chlorination of the outlet effluent stream. All putrescible galley waste will be macerated to less than 25 mm before release.

Impacts resulting from testing of the BOP will be minimised by using a glycol based control fluid which is of low toxicity, and has a relatively high biodegradability and low bioaccumulation potential compared to mineral oil- based control fluids.

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In order to reduce noise disturbance, the duration of drilling operations will be minimised and will utilise a semi-submersible drill-rig rather than a drill ship, as the latter are generally regarded as noisier (Richardson et al., 1995). Noise output will be minimised by keeping the test-flaring period to an absolute minimum, and by optimising support vessel and helicopter operations. In addition, continued observation of marine mammal activity will be carried out to monitor any behavioural reactions.

During Decommissioning

No mitigation measures are proposed, as potential impacts are not anticipated with floating the semi-submersible rig off site.

7.7.1.2 Field Facilities Mitigation Measures

During Installation

The main mitigation methods associated with field facilities installation are those associated with physical disturbance of the seabed. During well tie-in and installation of the flowlines, mats will be used, trenching will be kept to a minimum and where practicable, small, less stable trenches will be used to encourage natural backfilling.

During Operation

To minimise the impact resulting from discharge of hydraulic fluid at the subsea facilities, a glycol:water mix (50:50) will be used, this mixture is an environmentally benign, low toxicity, high biodegradability, low bioaccumulation hydraulic fluid.

During Decommissioning

A study will be undertaken prior to decommissioning to determine the most appropriate methods of decommissioning the different parts of the subsea development. The study will include environmental issues, and review the impacts from each decommissioning option. The final recommendation for decommissioning will be agreed with all relevant authorities, and will include measures to mitigate any impacts that may be caused during the works.

7.7.1.3 Pipeline and Umbilical Mitigation Measures

During Installation

The main mitigation methods associated with pipelaying operations are those associated with physical disturbance of the seabed:

• a dynamically positioned laybarge will be used during pipe laying. This will reduce disturbance through anchoring operations;

• during dredging operations, the use of a suction dredger will minimise effects, as this discharges cleaner water than other dredge methods. The

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dredged material will be temporarily placed within the pipeline corridor and then used to backfill the excavated trench.

• during rock placement, a fall-pipe will be used to increase the accuracy of the operation and measures will be taken to ensure that the correct grading of rock is used; and

• during hydrotesting, the line used to collect the seawater to be used in the test will be fitted with filters and flotation devices in order to minimise sediment disruption. Minimal concentrations of biocides, oxygen scavengers, corrosion inhibitors and fluorescent dye will be added to the water, and discharge of hydrotest water will be via the subsea facilities in the Corrib Field to achieve high levels of dilution. The umbilical will not require hydrotesting.

During Operation

The sacrificial anodes used for cathodic protection will be designed to dissolve slowly, such that only low concentrations of metals are released over a long time period (throughout the life of the pipeline). Dissolution of the anodes will only take place in the event that the other forms of external corrosion protection fail.

During Decommissioning

No mitigation measures are proposed, as potential impacts are not anticipated from leaving the pipeline and umbilicals in place. Removing the pipeline and umbilical from the seabed would generate similar levels of sediment disturbance to those of installation.

7.7.2 Nearshore Mitigation Measures

Nearshore mitigation measures have been developed to prevent, control and minimise potential impacts from the gas pipeline and water discharge pipe within Broadhaven Bay.

7.7.2.1 Gas Pipeline and Umbilical Mitigation

During Installation

During trenching and backfilling operations, the trench depth will be minimised and a mechanical trenching method will be used to reduce re- suspension of sediment. A post installation survey will be undertaken to ascertain seabed restoration. The footprint of the trench will be kept to a minimum.

The main mitigation methods associated with pipelaying operations in the nearshore area are those associated with use of blasting. The 1999 and 2000 route surveys were undertaken in order to select a route through soft

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sediment in order to avoid as far as possible, the requirement for blasting. However in the nearshore area the route cannot avoid crossing some areas of shallow rock.

Discussions will be held with appropriate authorities to ensure that the most suitable mitigation measures are utilised to minimise impact to the marine environment.

The possible zone of impact on marine mammals will be determined from the explosive charge size required. A number of steps will be taken to mitigate the effects of the blasting operation, including the drafting of a specific Environmental Management Plan to be agreed with Dúchas, cetacean experts and other relevant bodies. Monitoring prior to, during, and after the operation by recognised cetaceans experts would form an essential part of this plan.

Dúchas would be notified prior to commencement of works and an Environmental Management Plan will be produced and approved by cetacean experts prior to carrying out the operation.

Once started, blasting operations would be completed in as short a period as possible to minimise the period of temporarily unavailable habitat, and to discourage cetaceans from returning to the area between blasts.

More detail on the underwater blasting methodology is presented in Sections 3 and11.

During Operation and Decommissioning

These are the same as described in Section 7.7.1.3.

7.7.2.2 Water Discharge Pipe Mitigation

During Installation

The mitigation measures for installation of the water discharge pipe are the same as those for installation of the gas pipeline (Section 7.7.2.1), as the water discharge pipe will be strapped to the gas pipeline and pulled out from the shore in the same operation.

During Operation

The main mitigation methods associated with this section of the development are concerned with the discharge of treated produced water and rainwater runoff from the Terminal into Broadhaven Bay.

Section 4 of this document provides a brief description of the options considered by Enterprise for disposal of the produced water, along with any Terminal site run-off waters. Section 9 provides a description of the treatment to which the waste water will be subjected prior to discharge.

The treated water which is discharged to Broadhaven Bay from the Terminal will have concentrations of metals which are all at, or below, their

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respective Environmental Quality Standards (EQS) values. The EQS values reflect the maximum level in the water body that may be present, without affecting biological communities in their functional processes, or otherwise giving rise to unacceptable adverse effects on the ecosystem or accumulation of substances that are harmful to the biota (EPA, 1997a). The concentrations of the various metals in the discharge are provided in Section 9, along with their measured summer background concentrations in Broadhaven Bay, the background levels should be considered only as indicative (within an order of magnitude), as they are likely to vary throughout the year. Further monitoring will take place in Broadhaven Bay to characterise the background levels more fully (see Appendix 7.5).

Methanol will, on the whole, be recycled in the Terminal. More information on methanol discharge and recycling is provided in Section 9. There may also be extremely small traces of well fluids and inhibitor chemicals remaining in the methanol when it is discharged. The methanol loading of the discharge will be 0.3 mg/l, which complies with the EQS.

The oil and grease discharges relate to material that is washed off industrial plant by rain, or accidentally spilled onto impermeable surfaces within the Terminal and washed into the contaminated drain system. The amount of discharge estimated relates to the specified treatment capability of the Terminal plant, which will reduce the level of oil and grease in water to EQS level. It is anticipated that annually 20 kg of oil and grease will be discharged from the Terminal in this way. This level of discharge of oil and grease is insignificant.

The treated TOC discharge is expected to rapidly dilute within Broadhaven Bay, before mixing with open Atlantic water.

Enterprise will use the best available techniques (BAT) to treat the water before discharge. Enterprise are committed to producing a discharge in which the levels of contaminants are at, or below, their environmental quality standards (EQS). The EQS levels (EPA, 1997a) apply generally to open waters. Measurements of waters for comparison against EQSs are usually taken some distance from a discharge source, the discharge then having been able to dilute into the surrounding waters. The fact that all constituents of the water discharge into Broadhaven Bay will be at, or below, the EQSs at the end of the pipeline, is a significant mitigating measure. The standard requirement for a discharge would be to achieve the environmental limit value (ELV) at the end of the pipeline, and this level is usually higher than the EQS. There is no requirement under current legislation that discharges be reduced to EQS levels.

In addition to the commitment to provide such high levels of water treatment in the Terminal, Enterprise have also carried out detailed hydrodynamic modelling for Broadhaven. The model has been used to optimise the location for the end of the discharge pipeline with regard to its dispersion characteristics, and the selected discharge location is presented in Section 9.

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During Decommissioning

Decommissioning methodology for the water discharge pipe will be the same as that for the export pipeline, therefore, the same mitigation measures will apply, see Section 7.7.2.1.

7.7.3 Landfall and Sruwaddacon Mitigation Measures

Mitigation measures in this section have been developed to prevent, control and minimise potential impacts from the pipeline landfall and Sruwaddacon crossing points.

7.7.3.1 Pipeline and Umbilical Landfall Mitigation Measures

During Installation

Construction impacts at the landfall and Sruwaddacon crossings points will be reduced through the following mitigation measures:

• hard standing will only be constructed in areas likely to be used regularly by construction plants or vehicles. Any hardstanding will be removed as soon as possible after construction has finished; and • no local sand or mud will be removed from the site and any excess material will be spread out on site following consultation with Dúchas.

Landfall mitigation measures:

• the area of habitat disturbance will be kept to a minimum during construction; • prior to landfall construction, a survey will be undertaken to identify and avoid the location of sensitive habitats or protected species which could be affected by the proposed landfall construction activities. This survey will be discussed and agreed in advance with Dúchas and any appropriate mitigation measures taken; • landfall construction works will avoid the main nesting period of the little tern (May to July); and • the landfall site will be restored to the pre-entry survey condition using local species. There will be immediate reinstatement of soft shore and sand dunes at Dooncarton, and specifically the mouth of Sruwaddacon Bay, where the landfall activities will take place.

Crossing point mitigation measures:

• the area of habitat disturbance will be kept to a minimum during construction; • construction through the Sruwaddacon will be undertaken over as short a time period as possible; • silt traps will be used during construction of the Sruwaddacon crossings to minimise siltation of the watercourse;

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• as the Sruwaddacon is important for breeding, migrating and overwintering birds, the construction of the two crossings will be scheduled for late summer/autumn (August–September) to avoid these periods; • the two crossings of Sruwaddacon Bay will be reinstated to their original condition using local species; and • no construction material or spoil shall be deposited anywhere within the cSAC and SPA.

During Operation and Decommissioning

These are the same as those in Section 7.7.1.3.

7.8 Predicted Impact of the Proposed Development

7.8.1 Predicted Offshore Impacts of the Proposed Development

7.8.1.1 Predicted Drilling Impacts

During Rig Positioning

The impact on benthic faunal communities from rig positioning, running and setting of anchors and pulling of anchors, is likely to be negligible, due to the small area affected and the fact that disturbed areas will be re-colonised rapidly by natural recruitment. The impact on demersal fish is also considered to be negligible, as the majority of commercial demersal species tend to concentrate in the coastal areas and the current regime in the area will effectively disperse any re-suspended sediment. Fish species are highly mobile and will generally avoid unfavourable conditions. The likelihood of release into the water column near to the seafloor of sediment-bound pollutants in a bioavailable form is very low, as measured background levels in sediments are relatively low, (Gardline, 2000).

During Operation

Discharge of WBM and cuttings during drilling is likely to result in a minor, localised impact on the benthic community through smothering effects. The benthic community in general is capable of withstanding minor periodic increases in sediment loading that occur naturally, and re-colonisation of the disturbed areas is likely to be achieved rapidly by natural recruitment. The localised toxic effects of mud chemicals on benthos are not anticipated to be significant, as all chemicals used will be of low toxicity and will quickly dilute and disperse. Only trace levels of heavy metals will be present in the barite and these will not be in a bioavailable form. The cuttings are free of oil. They initially form accumulations around the well locations, but subsequently are re-suspended and distributed more widely. There have been significant reductions in organic mud chemical concentrations in the sediments around the Corrib Field wells since they were drilled. This could be a result of chemical degradation or re-suspension or both.

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The current status of the benthic invertebrate populations in the Corrib Field is described in Section 7.3.3.1. It can be seen that the discharge of drilling muds has had an effect on the populations at some sites, the elimination of SBM discharges from future wells is expected to reduce the level of impacts from drilling.

Discharge of WBM and cuttings also has the potential to increase water column turbidity near the seafloor. However, as mentioned above these effects are expected to be short term and transient.

Although LTOBM will be used during drilling for the lower hole sections, this will not have an impact on the marine environment, as the cuttings will be transported ashore for disposal.

Discharged cement slurry will initially disperse into the water column. The high pH may have a localised effect on benthos and demersal fish. However, this impact will only be negligible, as the buffering properties of seawater will neutralise the discharge. Any solids will ultimately settle out onto the seabed.

It is anticipated that discharges of rig wash water, drainage water and waste water (including black water, grey water and galley wastes), will have a negligible, localised impact on plankton and pelagic fish in the immediate vicinity of the discharge pipe. Impacts will be limited as dilution and dispersion of these discharges will be rapid.

Discharge of BOP fluid will have a negligible effect, as a glycol based low toxicity product will be used, and only small quantities will be released periodically.

It is anticipated that underwater noise generated through the operation of the drilling rig will have a negligible impact on fish and cetaceans, the noise will be of a relatively constant level, and it is likely that any fish or cetaceans in the area will move a short distance away from the rig, if they are being disturbed.

During Decommissioning

Impacts are not anticipated during floating of the semi-submersible rig off- site.

7.8.1.2 Predicted Field Facilities Impacts

During Installation

Seabed disturbance from the installation of the field facilities is anticipated to have a negligible impact. The area of habitat lost would be minimal (combined footprint for the gathering manifold and pipeline end manifold 392 m2). Physical disturbance of benthic faunal communities and crustaceans is only likely over a localised area of seabed. The impact on demersal fish is also considered to be negligible, as the current regime in the area (current velocity can reach 50 cm/s, see Section 9) will effectively disperse any re-suspended sediment. The likelihood of release into the

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water column, near to the seafloor, of high levels of sediment bound pollutants in a bioavailable form, is very low, as measured background levels in sediments are relatively low (Gardline, 2000).

During Operation

Intermittent discharges of low volumes of hydraulic fluid (glycol:water) at the subsea completion will have a negligible impact on benthos and demersal fish as the glycol has a low toxicity, high biodegradability and low bioaccumulation potential. In addition, dilution and dispersion will be rapid.

During Decommissioning

These will be as described in Section 7.5.1.2.

7.8.1.3 Predicted Pipeline and Umbilical Impacts

During Installation

Installation of the pipeline on the seabed, and the burying of the umbilical using a remote jetting trencher, will have a negligible, short-term impact (offshore pipelaying will take place over a 25 day period) on water column turbidity and subsequent smothering of organisms due to both the rapid re- colonisation, and the low levels of sediment bound pollutants (Gardline, 2000).

Rock placement will have a negligible impact, with loss of habitat type over a localised area. It is also anticipated that colonisation of this new hard substrate will be rapid and could ultimately, increase species diversity in the area.

During hydrotesting and commissioning of the pipeline, water will be abstracted from offshore and then discharged, after use, back into the marine environment. This discharge is anticipated to have a negligible impact, as the use of corrosion inhibitors, dyes and biocides will be minimised and discharge via the subsea facilities will maximise dilution.

During Operation

The leaching of trace metals from the sacrificial anodes are anticipated to have a negligible impact on the marine environment. They will dissolve very slowly over the life of the pipeline (15 –20 years), releasing small amounts of metal ions into the water column which will be diluted immediately by the natural water movements along the pipeline route.

During Decommissioning

No predicted impact is anticipated during decommissioning of the pipeline and umbilical.

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7.8.2 Predicted Nearshore Impacts of the Proposed Development

7.8.2.1 Predicted Pipeline and Umbilical Impacts

During Installation

Within Broadhaven Bay, both the pipeline and the umbilical will be buried. However, the impacts of increased turbidity and smothering of organisms from this activity will be negligible, for the same reasons as described in the offshore section of the pipeline route.

Noise impacts during installation of the pipeline within Broadhaven Bay are anticipated to be negligible. The burial method for the pipeline will be by trenching vehicle, and that for the umbilical will be by jetting the sediment away from beneath it. As the operations move continuously, they will not be resident at any one location for any length of time. The proposed period for nearshore pipeline construction, April-June, is also outside the period when peak numbers of cetaceans are likely in nearshore area (August-October).

The main issue regarding the predicted impacts of pipeline installation within Broadhaven Bay, however, is concerned with blasting. Although the impact of blasting on marine mammals can be severe, as described above, mitigation measures will be put in place, to ensure that cetaceans and seals are outside the zone of influence of the blasting operations, and will significantly attenuate blasting noise in order to reduce the impacts on fish. It is therefore expected that the impacts on cetaceans on seals will be negligible, whilst impacts to be fish are expected to be minor. Further information on the effects of underwater noise are provided in Section 11.

During Operation and Decommissioning

These are the same as for the export pipeline in the offshore zone; see Section 7.8.1.3.

7.8.2.2 Predicted Impacts of the Water Discharge Pipe

During Installation

The predicted impacts during installation will be the same as those associated with installation of the export pipeline, as the produced water discharge pipe will be strapped to the gas pipeline and pulled out from the shore in the same operation.

During Operation

Discharges

The dispersion of the proposed discharge from the Terminal has been modelled under a range of different weather conditions (the discharge will contain rainwater in addition to treated waste water), and information on these model runs is provided in Section 9, and Appendix 9.1. It can be seen that given discharge at EQS levels, and the dilution available in close

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proximity to the proposed end of the pipeline (at approximately 40 m water depth), none of the metals discharged will be at greater than 0.5% above their natural background concentration at 500 m from the discharge point (see Section 9 for background concentrations). In the immediate vicinity of the end of the outfall the range of metal concentrations (above natural background) will be 0.1 – 2.2 % (in the worst case).

There have been locally voiced concerns that exploited shellfish may become contaminated with trace metals (particularly mercury). The acceptable levels of trace metals in seafoods are laid down by a number of national and international authorities, and in almost all instances these are only exceeded where significant local sources of contamination are present. Given the level of treatment of the waste waters from the Corrib development and the high dilution/dispersion available in Broadhaven Bay, it is extremely unlikely that measurable bioaccumulation of metals will occur for the following reasons:

• mercury and selenium are unlikely to be problematic, due to the fact that they have only slightly higher concentrations in the waste waters than in Broadhaven Bay (“low enrichment factors”); • arsenic is not anticipated to be of significance in the present scenario, in part due to its relatively low enrichment in the waste waters, and also because of its propensity to accumulate in relatively non-toxic organic forms in marine organisms (Francesconi & Edmonds, 1994; Phillips, 1994; Valette-Silver et al., 1999); • chromium, lead and manganese having low levels of enrichment, are be expected to move from the water to the sediments relatively rapidly (Förstner & Wittmann, 1983; Phillips & Rainbow, 1993), and their rates of mobilisation from the sediment reservoir thereafter will be low; • barium and nickel are not generally of consequence in marine waters or marine organisms (Förstner & Wittmann, 1983), and are not, therefore, expected to exert effects of significance due to the development addressed here; • copper and zinc are metabolically regulated by many marine organisms (or in specific tissues of these, e.g. the muscle of finfish – see Phillips & Rainbow, 1993). The levels of their enrichment in waste waters commonly exceed those predicted in the present scenario, without overt observable impacts in coastal waters; and • cadmium and silver are of significant toxicity in marine waters. Neither of these elements associates particularly heavily with suspended inorganic particulates (Nriagu, 1980; Cain & Luoma, 1990). Given the fact that both cadmium and silver are intended to be discharged from the outfall at concentrations equal to or less than the EQS values, it is extremely unlikely that adverse impacts will occur within the receiving waters, to either flora or fauna. This is particularly the case, given the relatively high dilution/dispersion in the proposed outfall area.

Although the data that are presently available suggest that the effects of the treated water discharge are likely to be negligible (and may not even be observable at any significant distance from the outfall), monitoring will be completed to confirm this. In order to do this, a sampling programme has

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been proposed. A brief description of this survey is provided in Section 7.9, while it is described in more detail in Appendix 7.5.

Discharge of Methanol, Oil, Grease and Total Organic Carbon

The high dilution available in Broadhaven Bay and the low volumes of organic material discharged, will result in a negligible impact to Broadhaven Bay.

Physical Impacts

The speed of the water being discharged from the pipeline will be up to 1.26 m/s (approximately 2.5 times faster than the natural currents in the Bay during spring tides). Small organisms which happen to be in the water column in the vicinity when water is being discharged are likely to be moved by the current from the discharge. However, the type of animal which is moved (e.g. plankton) is likely to be swept around by the tidal currents and waves in the Bay during normal conditions. Larger faunal species are expected to avoid the area directly above the end of the pipe during the period of discharge. The physical influence of the discharge stream will decrease quickly and organisms that are a few metres away are unlikely to experience any abnormal effects.

The discharge will be at ambient temperature, there will, therefore, be no thermal impacts to the environment.

During Decommissioning

It is currently envisaged that the discharge pipeline will be capped and left in place on the seabed, however the decommissioning study close to the end of Field life will be used to evaluate the options at that stage. Given the current proposed strategy, it is envisaged that the resulting impacts will be negligible, and will result only from limited boat work and sediment disturbance at the diffuser location.

7.8.3 Predicted Impacts at the Landfall and Sruwaddacon Crossings

7.8.3.1 Predicted Impacts of the Pipeline and Umbilical

During Installation

Construction of the landfall and crossing points of the Sruwaddacon has the potential to cause habitat disturbance due to noise, excavation activities, increased traffic loading and aqueous and non- aqueous emissions. The impacts listed above, however, will be short-lived and transient, with construction activities limited to a period of 8 months.

The little tern colony on a shingle/sandpit area to the north of the proposed landfall should not be affected by the activities due to their distance from the landfall site (500 m) and the fact that construction operations will be scheduled outside the nesting period. Similarly, corncrakes on the north

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shore of the Sruwaddacon should not be impacted, as construction will be scheduled to avoid their nesting period if they are present.

The two crossing points of the Sruwaddacon will be open-cut, with the potential for release of sediment and siltation of the watercourse. However, the use of silt traps and the rapid movement of water through the Sruwaddacon (scouring and strong tidal movement recorded during the crossing point surveys, see Section 7.3.3), will reduce any impacts on flora and fauna to a minor level. The subtidal sections of the crossings will be completed in as short a time as possible, which will reduce the period of the impacts.

The marine works associated with the landfall will require the presence of a small stationary jack-up platform which could generate underwater noise during the pulling and pipeline lowering operations. However, due to the limited period of this activity, and the shallow water involved, it is not anticipated that this will have a significant impact on cetaceans.

In general, subsea noise from construction within the Sruwaddacon will not travel great distances due to attenuation at the sea surface and seabed, as a result of the shallow water.

The landfall site runs parallel to the boundary of the Glenamoy Bog Complex SAC, where it passes through the fields to the south of the small sand dune system. The adjacent sand dunes and associated sandy foreshore are highly mobile. This landfall area is not of high ecological value in terms of habitat and therefore, predicted impacts to the SAC are anticipated to be negligible.

In addition to the above, the two pipeline crossings are within the Sruwaddacon Bay SPA, the habitats of which are of importance in terms of supporting fauna – in particular wintering wildfowl. On the western side of the Bay the route passes close to an area of algal beds that are a feeding ground for over–wintering brent geese. The second crossing of Sruwaddacon Bay crosses inter-tidal sand flats and foreshore, which are of high potential significance in terms of wildfowl usage. The mitigation measures in place, particularly those regarding scheduling construction outside the main period when breeding, migrating and overwintering birds are within the Sruwaddacon, will reduce disturbance and long term impacts will be minimal.

7.9 Monitoring

7.9.1 Corrib Field

Invertebrate sampling will take place in the Corrib Field at a frequency to be determined in discussion with the Marine Institute. As there will be no further discharges of organic phase muds in the Field, the sampling is expected to record the recovery of the invertebrate populations.

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7.9.2 Pipeline Route

During the construction and pipe-laying phases, cetaceans will be closely monitored in the immediate vicinity of the vessels.

In the years following construction, the pipeline route will be surveyed periodically using a combination of ship deployed ROV and sidescan sonar surveys. Duration of the surveys will be a few weeks in each case and the survey spread will be continually moving along the pipeline route.

7.9.3 Broadhaven Bay

7.9.3.1 Cetacean Survey

A monitoring programme will be undertaken prior to, during and after the construction work, in Broadhaven Bay order to provide information on the level of usage and importance of the Bay and adjacent areas to cetaceans. The results from the first phase of the survey (pre-construction) will be used to formulate an environmental management plan (EMP) to cover the construction programme (including blasting work). Any such EMP would need to be agreed with Dúchas prior to any blasting.

Briefly the main elements of the survey work will be as follows:

Pre-construction survey - Oct 2001 to March 2002

During suitable weather conditions in autumn-winter, researchers will conduct intensive land-based monitoring for cetaceans from a number of prominent, well-elevated positions around the Broadhaven Bay and Erris regions. This will be performed using high-powered telescopes and digital theodolite, allowing the positions of sighted animals to be accurately determined.

RIB-based visual surveys may also be conducted opportunistically (estimated 1 per month) along a defined GPS-based route within the Broadhaven Bay area and possibly extending east and west of the outer bay. All such line-transect surveys will incorporate opportunistic photo- identification work using stills camera equipment to investigate whether particular species (e.g. bottlenose dolphins) are resident in the region.

A dedicated acoustic element of the project will involve the use of hand- deployed porpoise detectors (PODs) and sonobuoys for the detection of toothed whale/dolphin species. In addition an array of bottom-mounted remote listening devices (known as a "pop-up") may be deployed off the Mayo coast, to monitor and record baleen whale vocalisations in the region.

In-parallel monitoring - April to September 2002

Researchers will continue with intensive land-based monitoring for cetaceans using high-powered telescopes and digital theodolite. One part- time researcher will be employed for this spring-summer period to maximise the data potential of the study.

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Visual surveys will continue to the specified line-transect design with a potential summer extension to coastal waters between Erris and Benwee Heads and up to 10 km from shore. It is envisaged that a minimum of two boat-based surveys will be conducted per month during this period when weather conditions will be more favourable.

This intensive period of boat-based work will incorporate standard photo- identification and acoustic monitoring in the study area and, in the days immediately surrounding any proposed blasting within Broadhaven Bay, the researchers will implement a more rigid survey-effort in the region by drawing on experienced personnel from University College Cork for several days.

Such operations will also involve the drafting of procedures and operational controls, in collaboration with Dúchas personnel, to mitigate and minimise the impact of such activity on cetaceans and fish in the region. It is proposed that these measures be adopted by the operators charged with pipe-laying and blasting operations in the area.

Post-construction monitoring & analysis - October to December 2002

Field elements will be scaled down as necessary through the autumn in accordance with weather conditions and a 3-month period of data analysis and report preparation will follow the cessation of field operations in late October.

7.9.3.2 Seabed sediments and biota

Pre- and post-project monitoring will be carried out within Broadhaven Bay, to substantiate conclusions concerning the environmental impact of produced water discharge. This is desirable, even though the data that are presently available suggest that the effects of the treated waste water discharge are likely to be negligible.

Monitoring will be undertaken to ascertain the quality of the treated waste water. This monitoring will be in accordance with the terms of an integrated pollution control licence from the Environmental Protection Agency and is discussed in Section 9 of this EIS.

The monitoring to be undertaken will encompass a number of aspects selected to provide a robust picture of the level of trace elements in specific reservoirs. A detailed description of the Monitoring Survey is provided in Appendix 7.5. The following describes the general monitoring scheme that is proposed:

• sediments will be sampled over a grid located around the outfall, emphasising the directions of the prevailing currents. The precise sampling pattern will depend on whether effluent discharge will occur on the ebb tide only;

• in addition, the finer sediments (often also exhibiting higher levels of organic matter) that are found in particular near-shore embayments, will

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be sampled. These sediments are more likely to accumulate trace elements than the coarser sands found close to the outfall site. While it appears likely that the offshore dilution and dispersion will be sufficient to eliminate any observable impacts close to the shoreline, the sampling of finer sediments in near-shore locations is proposed in order to confirm this; and

• selected biota will also be sampled. It is proposed that samples of plaice (Pleuronectes platessa) and oysters, or mussels (Mytilus edulis) should be employed for this biomonitoring programme. The use of two species is preferred, as each will respond to a distinct mixture of metals in the various phases in water (Phillips, 1979). Plaice are proposed for inclusion, as they can be taken throughout the study area; are bottom- dwellers (which tends to increase their level of exposure to contaminants); commonly remain in the same general area over significant periods; and are known to be useful biomonitors of particular metals (Pentreath, 1976a, 1976b, 1977a, 1977b). It is notable, however, that both muscle and liver tissues will be required for analysis, as certain of the trace elements are metabolically regulated in the muscle tissues of finfish (Pentreath, 1976a; Phillips & Rainbow, 1993). Both oysters and mussels are very widely employed for the biomonitoring of trace elements (e.g. see Phillips & Rainbow, 1993; O’Connor, 1996; Joiris et al., 2000; Muñoz-Barbosa et al., 2000), and the decision on a preferred species will depend on their availability in the region. The use of cultured oyster stock from the nearby areas may be considered, at least if this stock is reasonably uncontaminated. The bivalves can be relocated using standard transplantation techniques (Young et al., 1976; Curran et al., 1986; Grout & Levings, 2001), and this will permit the study of a range of specific locations both in near-shore and offshore areas, as desired.

It is proposed to complete biomonitoring studies in both the area of the outfall and along the shoreline. Consideration will be made to include a species of macroalgae at the shoreline, in addition to the bivalve molluscs (Phillips, 1979; Brown et al., 1999). The preferred macroalgae would be knotted wrack (Ascophyllum nodosum), or bladder wrack (Fucus vesiculosus), both of which are locally abundant and have been widely employed in previous biomonitoring studies elsewhere. Knotted wrack carries the advantage that it displays a nodal growth pattern, and samples can therefore be aged (Phillips & Rainbow, 1993). However, particular care should be taken with respect to the method used to remove particulate materials from the surface of the algal samples (Gledhill et al., 1998).

All sampling will take into account the impacts of external variables on the trace element concentrations found in sediments and biota (Phillips, 1980; Phillips & Rainbow, 1993; Ruiz & Saiz-Salinas, 2000). The international literature on this topic is extensive, and the design of a comprehensive monitoring programme of this type will account for seasonal effects. The timing of sampling of the biota will specifically consider this (as it relates to the spawning cycle of the organisms concerned). The samples taken will be representative of the populations/locations involved, and will permit the statistical comparison of both spatial and temporal differences in trace element abundance. This has implications for the number of individuals

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taken for biota, and the number of sub-samples of sediments collected at each site (Phillips & Rainbow, 1993).

A broad suite of metals will be analysed in the selected samples.

All monitoring will commence prior to the initiation of the project, with the sampling intervals after Terminal start-up modified according to the results obtained.

It is recommended that baseline and initial operational monitoring should be reviewed one or two years after Terminal start-up. Sampling intervals may be extended if the initial survey reveals an absence of impacts of significance.

Sruwaddacon

Reinstatement of the soft shore and sand dunes at Dooncarton, and specifically the mouth of Sruwaddacon Bay will be monitored by an experienced vegetation ecologist.

7.10 Reinstatement and Residual Effects

7.10.1 Offshore Area

No residual effects are anticipated in the offshore zone from the drilling activities, subsea facilities or the gas pipeline. No reinstatement has been proposed for this area.

7.10.2 Nearshore Area

No residual effects are anticipated from the construction and operation of the gas pipeline within Broadhaven Bay.

Contaminants discharged into Broadhaven Bay during the operational period of the Terminal will be sufficiently low due to the high levels of treatment, and highly dispersed due to the natural hydrodynamic regime in Broadhaven Bay not to cause any residual changes to the water quality of the Bay.

7.10.3 Landfall and Sruwaddacon

Provided construction can be undertaken during the periods agreed, and if the landfall and Sruwaddacon crossing points can be reinstated to their original condition, then there should be no residual effect from the development in this area.

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