Sherkin Island Marine Station


Survey Work & Reference

Rocky Shore


Terrestrial Flora









Butterflies & Moths




Reference Collections






Survey Work &
Reference Collections


Rocky Seashore Survey

The Rocky Shore Monitoring programme was running from Sherkin Island Marine Station from 1975 until 2015, with 69 sites surveyed annually on Sherkin Island and the islands of Roaringwater Bay and in Dunmanus Bay. In 1995 the programme was extended along the coastline from Bantry Bay to Cork Harbour, increasing the number of sites to 144.

Sites were accurately relocated from year to year using maps, photographs and detailed site directions. A transect line was set out from the top of the shore down to low water, with quadrats (0.25m2) placed at vertical distances of 30cm. The mean tidal range in this area is c.3m, so the 30cm vertical distance measurement ensured that there were at least 10 stations at most sites. In practice, this number was variable and dependent on site conditions. For example, the transect at Cobh Slipway, Cork Harbour was only 6 stations whilst that of Lord Bandon's Tower in Dunmanus Bay was 22. Stations along the transect were set with permanent markings, which ensured that the quadrats were placed in exactly the same position each year. At each station the abundance of every species encountered within the quadrat was recorded and the data entered onto computer. More than 230 species of flora and fauna were recorded over the 144 sites.

There were seven sites on Sherkin Island, which were visited monthly from April through to October. At these sites two quadrats were laid down side by side at each station along the transect line, increasing the survey area.

2003 saw the publication of "The Ecology of the Rocky Shores of Sherkin Island - A Twenty-Year Perspective". It is the first major analysis of rocky shore data from the programme begun in 1975.

The book gives well-illustrated background information on the common species of the rocky shore together with how the rocky shore food web functions. The main focus of the book are the seven monthly shores on Sherkin Island. The book was written specifically to include people and to appeal to a wider audience than the academic community. For this we are indebted to the author, Dr. Gillian Bishop, the Stationís first marine biologist in 1975 and now an environmental consultant in Aberdeen, Scotland.

See also: Distribution Maps

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Phytoplankton Survey

Phytoplankton monitoring was the other major programme being carried out at Sherkin Island Marine Station. Phytoplankton refers to the microscopic plants found in the sea which form the basis of the food chain on which most animals depend. From 1978 a team of marine biologists surveyed phytoplankton populations in the area. Permanent stations were visited every 10 to 12 days from approximately April to November, in Roaringwater Bay and South of Sherkin, into the open Atlantic up to 12 miles. Water samples were taken at different depths at each station, down to a depth of 50m. The temperature and salinity readings were also measured. The water samples were then preserved and analysed to determine the population densities of each species. In 1996 we set up a sample station off the Marine Station landing stage and we did profile sampling every 4 days. Annually we looked at approximately 2,000 water samples from the 12 sites. Preserved samples are stored in the Station's archives since 1978.

The most well known aspects of phytoplankton studies are those relating to the "Red Tides" that have occurred. Red Tide is the name given to the phenomenon in which a population explosion or "bloom" takes place in a phytoplankton population, usually resulting in the discoloration of the water, which may be tinged with red (although other colours can be produced, depending on the pigmentation of the microscopic plants). The environmental and economic implications of certain species of phytoplankton have stimulated extensive research over the years. Some species contain toxins, which can become concentrated in filter-feeding animals such as mussels. The serious consequences arise when humans eat contaminated shellfish. Many species are also responsible for fish kills around the world. Species of special interest are Karenia mikimotoi (Gyrodinium aureolum), Dinophysis acuminata and D. acuta, as they have been responsible for some of the outbreaks around south-west Ireland.

Ireland's Marine Institute has its own monitoring and toxicity programmes. Details of these programmes can be viewed at the

See also:

Special on-the-spot Reports on Red Tides

"The Genus Alexandrium Halim (Dinoflagellata)"

"The Problems of Toxic Dinoflagellate Blooms in Aquaculture"

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Zooplankton Survey

Zooplankton is the name given to the small animals that drift with water currents in the sea. In 1979, a monitoring project began to study zooplankton in a manner similar to that of the phytoplankton monitoring project. A researcher was assigned to the project each year, with the aim of studying annual population changes. Sampling took place from the Station's 19' research inflatable at the same time as the phytoplankton was sampled. The areas covered were therefore the same as those covered by the phytoplankton survey. A zooplankton net was used to collect samples as a vertical haul, representing a column of water at each sampling station. Once back at the laboratory, identification and assessment of the species' composition took place using a binocular microscope, the samples having been preserved in formalin. A single vertical haul may contain forty or more species, amongst them some of the more important groups such as Copepods and Chaetognaths. An extensive reference collection was assembled over the years and this helped considerably with the identification of uncommon species.

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Terrestrial Flora Survey

The wild plants of West Cork have received less study than they deserve. Nevertheless there are many hints in the botanical literature of great richness, notably in the intensive study by Polunin (1949, 1950) of the islands of Roaringwater bay. Research on plants by young botanists based at Sherkin Island Marine Station confirmed this richness.

As a result of the work carried out at the Marine Station, the islands of Roaringwater Bay have been recognised as a botanical "hotspots" for rare plants. Twelve of the species found in the islands are included in the Irish Red Data Book. And a further two (Fiddle Dock and Deptford Pink) ought to be included in any future edition. The Deptford Pink was only discovered in Ireland as recently as 1992 when Sherkin Island Marine Station botanists found six plants on Horse Island. It is encouraging to see that, in 1996, the number had grown to 35.

We found a total of 627 different flowering plants, conifers and ferns (including hybrids and subspecies), which is an astonishing figure for an area of some 10 km2 in Ireland. Indeed, this would be a high figure for a similar-sized area of Britain, which has a larger flora than Ireland. The flora of Roaringwater Bay is thus of immense importance both nationally and internationally. The area is as rich as anywhere in North-Western Europe.

1996 saw the publication of "The Wild Plants of Sherkin, Cape Clear and adjacent Islands of West Cork", a flora that was the culmination of many years research by the Marine Station botanists. A supplement to the above flora was also published in 2011. Rather than marking the end of botanical studies at Sherkin, the publication of the Flora only served to fire our enthusiasm for further work. The Sherkin method of thorough and repeated surveying revealed some astonishing finds in an area that was hitherto oddly neglected by the majority of main stream botanists. In 1997 the Station began a new survey on the islands of Bere, Dursey and Whiddy in Bantry Bay. The Flora list, when the survey was completed, surpasses that of the islands of Roaringwater Bay. There is an herbarium of over 1,000 plants of the Bantry Bay islands in the Marine Station herbarium.

John Akeroyd, the noted botanist, oversaw the botanists at the Station, making annual visits for over 20 years.

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(Flowering Plants and Ferns)

The Sherkin Island Marine Station Herbarium contains over 2000 specimens of flowering plants and ferns. Of the 627 species recorded for the islands of Roaringwater Bay, 531 are represented in the herbarium - including many of the Roaringwater Bay specialities such as Lotus subbiflorus (Hairy Bird's-foot Trefoil), Rumex pulcher (Fiddle Dock), Tuberaria guttata (Spotted Rockrose), Viola lactea (Pale Dog-violet), Geranium purpureum (Little Robin) and a magnificent specimen of Babington's Leek (Allium ampeloprasm var. babingtonii). Of those species that remain to be collected, five are considered extinct and a further 26 have not been recorded in the islands since the 1950s.

Lucy Wright, who collected 445 specimens, initiated the plant collection in 1981-1982. Over the years the collection increased in size and, in many cases, there are now three specimens of each species.

In addition to the flowering plants and ferns, there are also collections of bryophytes (276 specimens), fungi (109 specimens) and lichens (100 specimens).

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Bird Survey

Since 1975 birds were regularly studied at the Station, and detailed breeding bird surveys of the islands in Roaringwater Bay were carried out. The geographical position and range of habitats provides good breeding sites for many types of bird. In addition the area is important for migratory birds that need food and shelter, especially when there are adverse weather conditions. Sea-bird passage along the south coast of Sherkin Island was monitored and collated with sea birds recorded at sea from the Station's research boat.

See: Bird Reports

"Ireland's Bird Life"

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Otter Survey

At Sherkin island Marine Station a continuing research project was set up to monitor otter, (Lutra lutra L.), activity on Sherkin itself and on the other islands of Roaringwater Bay. These included the following islands which were accessed by the Marine Station's boat:

Ardillaun, Badger Island, Bird Island, The Calf Islands, Carrigreagh, The Carthy's, Castle Island, The Catalogues, Clear Island, Coolim, Goat Island, Little Goat, Goose Island, Heir Island, Horse Island, Illaunnagrogh, Illaunrahee, Jeremiah's Island, Long Island, Mannin Island, Quarantine Island, Sandy Island, Skeam East, Skeam West, Spanish Island, Two Women's Rock.

The first otter survey of Roaringwater Bay was conducted in 1981.

A new addition to the project in the mid 1990s was an evaluation of activity along the banks of the River Ilen Estuary, which runs from the Mainland into the Bay, NE of Sherkin Island.

The survey involved traversing the coastlines and mapping tracks and signs to establish the distribution of areas utilised by otters.

Signs representing otter activity are:

Spraint sites - Spots where otters deposit their droppings.

Holt sites - Otter dens. (These were described and given the status of 'active' or 'non-active' depending on the evidence in and around the site).

Footprints, paths or runs, and lie ups (temporary rest sites) were also noted.

Sightings, although infrequent, formed an important part of the survey record.

See: Bulletin No 12: Otter Survey of Roaringwater Bay, South West Cork, Ireland, 1990.

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Diving Survey

The waters around Sherkin Island are ideal for those people interested in underwater surveying. The first survey was undertaken in 1975 by Dr. Keith Hiscock et al and various surveys were undertaken over the year. However due to costs and time, we discontinued diving surveys in 2001.

See: "Ireland's Marine Life"

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Sponge Survey

Two projects concerning sponges of Roaringwater Bay and adjacent areas were carried out from 1981 to 1983. A monitoring project was established to study the life cycle and changes of certain sponge species. This project was run with the wonderful help of Miss Shirley Stone - the noted world authority on sponges - then at the Porifera Section (sponges) of the British Museum (Natural History). A population survey of all species of sponges in the area, together with a study of their biology, was also run during 1982 and 1983. Methods used to survey the sponges included shore exploration and scuba diving. There is a major slide collection of sponge skeletons in the Marine Station archives from the Roaringwater Bay area.

See: "European Contributions to the Taxonomy of Sponges"

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Rockpool Survey

Rockpools are conspicuous components of the rocky shore and have been reported to contain both a diverse flora and fauna population. In 1995 Sherkin Island Marine Station began a rockpool survey.

In that year 48 pools were surveyed on both Sherkin (42 pools) and East Skeams (6 pools). In all cases the maximum length, width and depth of the pools were measured. Elevation was recorded (as the height below the barnacle line) to give a measure of the position of the pool along the shoreline. Pools were extensively searched for both flora and fauna species. In many cases the pools were partially bailed to reach deepest sections, however this measure was use sparingly to prevent destructive sampling. A species list of both flora and fauna was compiled where the former was noted via absence on presence and the latter, when applicable, via numbers counted.

Since the basis of the project was to set up a framework for a permanent study, detailed site descriptions for all pools were prepared. These included (per pool) a minimum of two photographs, a map of the pool in its surrounding area and written instructions. This will ensure that the correct pools can be relocated for future studies.

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Macrofauna Survey

Sandy beaches are the most widely distributed type of intertidal environments world-wide, but as they appear to be barren and inhospitable they are the least studied of all intertidal habitats. The aim of the research at the Sherkin Island Marine Station was to study a number of diverse sandy beaches for their macrofauna communities. In total twenty-eight sandy beaches, from Cork Harbour to Roaringwater Bay, were quantitatively sampled for their macrofauna populations between June and mid September 1996 and 1997.

Macrofauna are living organisms which inhabit beaches and which are retained by a 0.5mm sieve. This study is an extension of a number of surveys carried out by undergraduates from 1976-1978 on Sherkin Island.

Within Roaringwater Bay, County Cork, Ireland, sixteen beaches were sampled. Including seven on Sherkin island, three on Heir Island, two on Horse Island and one on East Calf Island. Beaches were examined on the uninhabited Islands of East Skeams, Middle Calf, Catalogues and Carrigreagh.

Along the Cork Coastline eleven beaches were surveyed, extending from Baltimore to Cork and including Tragumna, Rosscarbery Strand, Ownahincha Strand, Summercove, Robert's Cove, Inch Strand, Myrtleville Bay, Inchydoney, Long Strand and Howes Strand.

The methodology employed to sample the beaches involved setting up three line transects, from high to low water. At 10cm vertical heights along the transect, 4 replicate 0.01m2 cores to a depth of 15cm were taken. The core samples were sieved on the beach and any organisms collected were taken back for identification, with the aid of a microscope and appropriate keys. All new macrofauna species were fixed and preserved, a full specimen collection is held at Sherkin Island Marine Station.

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Insect Survey

As part of a number of surveys of the insects of Sherkin Island and the other islands of Roaringwater Bay, insects from the following insect groups were collected and identified:

Hymenoptera (bees, ants and wasps)

Neuroptera (lacewings, alderflies, snakeflies & antlions)

Dermaptera (earwigs)

Orthoptera (grasshoppers and crickets)

Coleoptera (beetles) See: Beetles Survey

Heteroptera (bugs)

All specimens are in the Station's archives.

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Beetle Survey

Coleoptera (Beetles) surveys was undertaken for 1980, 1981, 1991, 1992 1993 and 1995 on some islands in Roaringwater Bay. Sherkin Island was the main island surveyed. The list for all the islands now stands at 537 species. The collection of the beetles took place between May and September and involved sweep-netting, hand collection and pit-falling. All specimens are stored in the Marine Station archives.

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Butterflies & Moths

Lepidoptera work was carried out at Sherkin Island Marine Station in the following years: 1977, 1978, 1981-1983, 1985, 1986, 1991, 1992, 1996-2001, 2004 and 2005. This work makes Sherkin Island one of the most intensively studied places in Ireland for Lepidoptera. In 1997 a small number of sites were chosen for moth trapping (four besides the Marine Station). These sites were sampled intensively in order to try and catch a large proportion of the moths that fly in these areas. Butterfly transects were established in 1997 and were continued in 1998, 1999, 2001, 2004 and 2005.

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Seaweed Collection

There is an extensive collection of over 2,500 seaweed specimens in the Seaweed Herbarium.

Seal Survey

A survey of the Grey Seal population was carried out during 1985 to monitor possible changes since a 1981 survey. There are several sites around the bay in which seals may be observed hauled out on the rocks.

Flatfish Survey

Sherkin Island contains a number of areas important to flatfish as "nurseries". These are regions where the growth and survival of juvenile fish are enhanced due to less risk of predation, more amenable temperatures and a more readily available food source. A number of surveys were conducted by the station since 1980 and were concentrated on one such nursery, Kinish Harbour.

This site was fished regularly by beach seine between the months of June and September.

The flatfish populations were shown to change over time, with less fish being caught within Kinish Harbour towards the end of the summer.

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Reference Collection

The Sherkin Island Marine Station Reference Collection consists of:

Plant & Fern Herbarium:

Roaringwater Bay and the islands

Bantry Bay - Bere Island, Dursey Island and Whiddy Island

Seaweed Herbarium - including slide collection

Sponge Skeleton Slide Collection

Specimens of Marine Animals:

Over 3,500 preserved specimens of marine animals from mainly the Roaringwater Bay area - Sherkin Island and the Islands.

Otter Spraints.

Insect Collection:

Includes: Beetles, flies, dragonflies, moths and butterflies, aquatic bugs.

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Photographic Collection

Over 4,000 colour slides on the natural history of Roaringwater Bay.

Littoral and sub-littoral in the main, taken by Paul Kay and Pete Atkinson, former Sherkin Island Marine Station biologists. Both are now international natural history photographers. See: "Ireland's Marine Life"

Over 2,500 black and white photographs of ruins/buildings/sea shores of Roaringwater Bay.

This major collection was taken on the various islands of Roaringwater Bay by Paul Kay and Ian Watts during 1981 and 1982.

Collection of phytoplankton photographs of many of the species identified in the area.

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Meteorological Records

Sherkin Island Marine Station has, since July 1972, kept daily rainfall records and from August 1974 sunshine and temperature records. The station is the lowest (latitude-wise) in Ireland. The records are sent monthly to the Irish Meteorological Office (Met Eireann) in Dublin. We are one of a select number of stations whose records are used in the IMO monthly bulletin.

See: No 5: Rainfall of Sherkin Island 1973-1984

No 10: Sunshine Records of Sherkin Island 1974-1984

No 11: Air Temperatures of Sherkin Island 1975-1984

No 14: Air Temperatures of Sherkin Island 1985-1989

In 2000 Met Éireann embarked upon the TUCSON programme of Automatic Weather Stations (AWS’s). TUCSON stands for The Unified Climatological and Synoptic Observational Network. Given its location and the amount of the south coast not covered, Sherkin Island was chosen as an ideal location for an AWS. The station was commissioned on the 28th of April 2004.

The station measures:

Temperature: Air, Grass, Soil – 5cm,10cm,20cm, Earth – 30cm, 50cm, 100cm

Rainfall: 0.1mm & 0.2mm gauges

Solar radiation

Wind speed & direction

Atmospheric Pressure

Relative Humidity

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© Sherkin Island Marine Station 2021