Survey of Irish Coastal Lagoons, 1996
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Disclaimer No part of the content of this report should betaken as a statement of Dachas policy in respect of any of the matters addressed. The viewsexpressed by the authors are not necessarily those of Dachas. The user of this report assumesfull responsibility for any policy decisions and for any action taken as a resultof the conclusions contained in this report. Neither Dachas nor the authors may be heldliable for the outcome of any policy decision taken by users of this report. SURVEY OF IRISH LAGOONS, 1998 Volume I Part 2 Edited by Brenda Healy Contents Introduction Methods Site descriptions 1.Ballyteige drainage channels, Co. Wexford 2.Kilmore Lake, Co. Cork 3. An Loch Mor, Inis Oirr 4. Loch an Chara, Arainn 5. Loch Phort Chorruch, Arainn 6. Loch Fhada complex, Co. Galway 7. Loch an Aibhnin, Co. Galway 8.Loch Cara Fionnla, Co. Galway 9.Loch an tSaile, Co. Galway 10. Lough Athola, Co. Galway 11. Lough Bofin, Co. Galway 12. Maghery Lough, Co. Donegal 13. Sally's Lough, Co. Donegal 14. Kincas Lough, Co. Donegal 15. Moorlagh, Co. Donegal 16. Inch Lough, Co. Donegal Contributions by: Cilian Roden (Vegetation) Geoff Oliver (Aquatic Fauna) Jervis Good (Ecotonal Coleoptera) INTRODUCTION This volume contains the reports of the 16 lagoons surveyedin 1998. Their positions are shown on the map (Fig. 1) and Table 1. These reports supplement those written for the 20 lagoons surveyedin 1996. The total of 36 lagoons constitutes over a third of all Irish lagoonsidentified. Volume I part 1 contains a summary of the survey results, a classification of Irish lagoons,and discussion of their scientific value in national and international terms. For each site report, there is a general description ofthe lagoon, and separate accounts by different members of the survey team on Vegetation, Aquatic Fauna,and Ecotonal Coleoptera. Impressions of the sites sometimes differ between authors. The editorhas made no attempt to reach an agreed interpretation of the history, hydrology or likelyfuture for each site, believing that each author makes valid points. Each account ends witha short assessment of the scientific value of the site. A final evaluation of each site,taking into account all the different aspects investigated, is given in Volume I Part 1. Full descriptions of vegetation units can be found in Volume111, together with complete species lists. For aquatic fauna, a list of lagoonal specialistspecies and a complete species list for all 36 sites is given in Volume IV. Volume Vprovides more details on ecotonal Coleoptera. Descriptions of the habitats occurring in Irish lagoons and theircharacteristic flora and fauna are given in Volume I Part 1. Interpretation of maps The maps in this volume are reproduced from Volumes IIIand IV. They are based on OS 6" maps with the km grid added. As some ofthe maps are old, modifications were sometimes necessary. They were made using aerial photographs and on-site GPSreadings. In some cases the latter did not correspond precisely to map outlines. Thenames of lagoons are as shown on OS 1:50 000 maps (Discovery Series) and grid references arefor the centre of the lagoon. Irish names are used for lagoons in the Gaelteacht. The vegetation maps show positions of releves and snorkelling pathsin green and salinities, measured during faunal surveys, in red. The colour codesfor the benthic and marginal vegetation types are given at the end of this volume.Positions of aquatic faunal sampling stations are also shown on the vegetation location map. Theprecise position of faunal stations is shown on the location map for the aquatic faunal surveys.Positions of marginal beetle sampling stations are explained in the text. 1 16. Inch L. 15. Moorlagh 14. Kincas L. 13, Sally's L. 12. Maghery L. J (l cv ILI- 11. L. Bofin I J 10..L. Athola J, 9.L. an tSaile - (-AW '., 8. L. Cara Fionnla - - ,.;;1 7. L. an Aibhnin 6. L. Fhada complex 5. L. an Chara 4. L. Phort Chprruch -- /;,-A-_To 3. An L. Mor r L3 s 1. Ballyteige r Fig. 1. Location map of the 16 sites surveyed in1998. 2 Table 1.Sites selected for survey in 1998. Loch an Ghadai andthe upper pools were studied as part of the L. Fhada complex. Cara nagCaorach was sampled briefly as part of Cara Fionnla. Lagoon County Map No. Grid ref. Nearest town or village Ballyteige drainage channels Wexford 77 T 9506 Kilmore Quay Kilmore Lake, Whiddy Is. Cork 85 V 8548 Bantry Loch Mbr Galway 51 L 9802 Inis Oirr Loch Phort an Chorruch, Galway 51 L 8511 Arainn Loch an Chara Galway 51 L 8810 Arainn Loch Fhada Galway 45 L 9330 Cheathru Rua Thuaidh L. Fhada upper pools Galway 45 L 9531 Cheathru Rua Thuaidh Loch an Ghadai Galway 45 L 9330 Cheathru Rua Thuaidh Loch an Aibhnin Galway 45 L 9431 Muiceanach idir Dha Shaile Loch Cara Fionnla Galway 45 L 9628 Casla (Cara na gCaorach) Galway 45 M 9631 Cinn Mhara Loch an tSaile Galway 45 L 9539 Scriob Lough Athola Galway 44 L 6348 Clifden Lough Bofin Galway 37 L 5265 Inishbofin Maghery Lough Donegal 1 G 7209 Dunglow Sally's Lough Donegal 1 B 7216 Burtonport Kinkas Lough Donegal 1 B 7920 Kincaslough Moorlagh Donegal 1 B 7919 Annagary Inch Lough Donegal 6 C 3427 Buncrana SURVEY METHODS Vegetation Sampling Each lake was visited briefly during a preliminary survey inJune/July 1998. A more detailed survey was carried out in August-September, 1998. Sublittoral vegetation was examined by snorkelling through each lake. Aslittle vegetation was found below 5m, this method was sufficient to obtainan impression of the sub littoral diversity of each site. For every subjectively recognised vegetation type,a species list was made from a 2 x 2m area. A rough sketch mapwas then made of the distribution of vegetation. Data was recorded on a plastic slate. Voucher specimens were collectedand examined later. The limitations of this method include the difficulty of making detailedspecies lists or observations at depths greater than 2m. It was also difficult todetermine the exact position of each sample, as maps could not be carried or extensive notes made. Equally,salinity readings could not be taken when snorkelling, therefore in this account, the accurate dataobtained by Mr. G. Oliver are used. These readings are presented on the maps which showthe locations of sampling points. This procedure is justified because on most occasions the botanicaland zoological surveys were carried out at same time. The advantage of the methodis that it permitted large areas to be examined and even remote sites could be easily reached withoutthe need to transport diving equipment such as regulators or bottles. At each site a plankton sample was collected using a30 µm mesh net. The plankton was then preserved in Lugol's iodine for later examination. Marginal vegetation was surveyed by first examining aerial photographs, andthen exploring the lake perimeter on foot (except in the caseof Loch a tSaile, where only part of the lake was examined due to its very large size). 1x lm releves were made of each of the different 3 types of vegetation that were seen. A sketch map ofthe major vegetation types was then made. Site photographs and underwater photographs were taken where possible butin general it was found that underwater photography was very difficult due tothe quantity of suspended material in lagoon water. Identification Most species identifications were easily made using standard floras (Clapham,Tutin, Moore 1987; Seaweeds of the British Isles 1985-1993, Moore 1986,Tomas 1996, Dodge 1982). However certain groups presented difficulties: Ruppia. The two species of Ruppia, R. maritima and R.cirrhosacan supposedly be distinguished on the basis of vegetative characters (Verhoeven 1979), howeverPreston (1995) states that in British or Irish material this is notpossible and fruiting material is necessary. An analysis of material collected during this survey conformed to Preston'sopinion and no correlation could be found between leaf shape and fruit orpeduncle morphology in many cases. An exception was the material collected in Loch an Aibhninwhere plants with obvious R. cirrhosa fruits also had broad blunt leaves. For this reasonno attempt was made to identify non- flowering Ruppia to species. The variety termed R. maritima var.brevirostris (Verhoeven, 1979) with very short fruit stalks was found at Inch andBallyteige. Voucher specimens were collected from all fruiting populations and these are currently being studiedby C.D. Preston. Potamogeton. Only one species, the easily recognised P. pectinatus wasfrequently encountered. An unusual form of what is thought to beP. pectinatus is currently being examined by Mr. Preston. It was found at two sites andprobably corresponds to var. flabellatus. Cladophora. Samples of this difficult genus were collected and preservedin 70% alcohol whenever encountered. This material was examined by microscope and provisionallysorted into different groups. An attempt was made to name the formsthat had been recognised. The European expert Prof.. C Van den Hoek kindly agreed toexamine some of the material, especially samples thought to be the rare C. battersii. These,along with examples of the other groupings were sent to Prof. Van den Hoek who confirmedthe identity of C. battersii and named specimens of the other groupings. All the drift Cladophora collectedwere thought to belong to a single species and Prof. Van den Hoek determined two samplesfrom this grouping to be Cladophora vagabunda. On this basis all the drift material inthe lagoons is assumed to be C. vagabunda but it must be stressed that this material isat times impossible to name without culture studies (Van den Hoek 1963) so only the materialconfirmed as C. vagabunda by Prof. Van den Hoek should be formally accepted as such. Chara. In general material in this genus was easily recognisedand the identification was confirmed by Mr.