Cryptic Species of Sea Potato

The Sea Potato, Echinocardium cordatum

A member of the Heart Urchin family (Loveniidae), the Sea Potato (Echinocardium cordatum) is probably most familiar to most people from the testsof the dead animal washed up on seashores. Live specimens can be quite elusive as the animal burrows into fine sand using the dense mat of spines that cover its body (1). It burrows to between 10 and 20 cm from the intertidal to the subtidal and the offshore (2), where it acts as a deposit feeder, using its tube feet to collect particles (3).

Empty Test of Echinocardium cordatum

E. cordatum is found in temperate oceans all over the world, and was considered a cosmopolitian species (2). However sequencing of ribosomal DNA from individuals from Atlantic and Mediterranean populations showed that two distinct monophyletic groups exist, and suggests that the species may be actually represent several taxa, a complex of cryptic species (4). Using fossil data, it was estimated that divergence between the two groups occurred c. 6 million years ago.

Echinocardium cordatum Burrowing into Sandy Substrate

References:

1. Sterry, 2004 Collins Complete Guide to Irish Wildilfe p. 176
2. Egea et al., 2011 Comptes Rendus Biologies (In Press, Uncorrected Proof)
3. Challinor et al., 1999 A Beginner's Guide to Ireland's Seashore p. 167
4. Chenuil and Feral, 2003 Echinoderm Research 2001 pp. 1-7

Water Fern: A Useful Alien

Water Fern, Azolla filiculoides

The Water Fern Azolla filiculoides belogs to the only genus of floating ferns. A native of the West Coast of South, Central and some of North America (1) it has become naturalised in Asia and at least 16 countries in Europe (2). It has been recorded in 14 of the 40 vice counties in Ireland (3) where its presence has been attributed to discarding of material from ornamental ponds and aquaria. Ongoing colonisation may be mediated by wildfowl carrying frond on their feet from site to site (2).

Frond and Roots of the Water Fern, Azolla filiculoides

Individual plants are floating fronds 1-2 cm in diameter with hair-like roots dangling into the water (4). Sori are produced at the base of side branches, producing spores that ripen from June to September. As the plants get older, they produce anthocyanins which lend a purple-pink tinge to the fern. The numbers of fern from year to year at a site may fluctate (3).
Ecologically, the Water Fern poses a threat to many native plants and invertebrates due to the tendancy of the fronds to clump together, often in their millions. This habit has been shown have a significant negative effect on submerged macrophytes such as Potamogeton crispus (5). Successful biological control has been achieved using a frond-feeding weevil, Stenopelmus rufinasus (6).

Water Fern, Azolla filiculoides, Covering a Pond

A filiculoides obtains its nitrogen from by a symbiotic relationship with the blue-green alga Anabaena azollae (7). This poses a problem in its aquatic habitat as its presence may lead to eutrophication (2), but this feature of A. filiculoides has been exploited in the cultivation of rice where it has been suggested that a fallow season crop of the fern in paddyfields could supply up to 50% of the nitrogen requirements for rice (8). While it is also used as a feed for pigs in areas such as Colombia, it has proved to have limited digestibility (9).

Water Fern, Azolla filiculoides

A. filiculoides has interestingly also been shown to be an excellent biosorbent due to its ability to bind and concentrate metal ions from aqueous solutions (10). Indeed, in mining operations in South Africa its ability to recover gold from effluents has shown to be quite efficient (11).

References:

1. Houghton Cambell, 1893 Annals of Botany 7 pp. 155-184
2. O'Mahony, 2009 Wild Flowers of Cork City and County p. 330
3. Reynolds, 2002 A Catalogue of Alien Plants in Ireland pp. 48-49
4. Phillips, 1980 Grasses, Ferns, Mosses and Lichens of Great Britain and Ireland p. 109
5. Janes et al., 1996 Hydrobiologia 340 pp. 23-26
6. McConnachie et al., 2003 Biological Control 28 pp. 25-32
7. Page, 1988 Ferns: Their Habitats in the British and Irish Landscape
8. Talley and Rains, 1979 Agronomy Journal 72 pp. 11-18
9. Leterme, 2010 Animal Feed Science and Technology 155 pp. 55-64
10. Fourest and Roux, 1992 Applied Microbiological Biotechnology 3 pp. 399–403
11. Antunes et al., 2001 Biotechnology Letters 23 pp. 249-251

Genetic Integrity of the Red Deer in Ireland

Red Deer, Cervus elaphus, : Two Hinds (Left) and a Stag (Right)

The origin of the Red Deer (Cervus elaphus) in Ireland is obscure. Skeletal remains of animals have been found and dated from 27,730 years before present up until 11,790 years before present when evidence for the deer disappears until 4,190 years before present (1). Whatever the reason for this 7,500 year gap, it indicates that the current population of Red Deer in Ireland is descendant from human mediated introductions: indeed the earliest record of such an event is in 1246 when Red Deer were moved from the Royal Forest in Chester, England to the then Royal Forest, Glencree, Co. Wicklow (2). The Red Deer population in the Killarney National Park was in the past believed to be the only surviving animals derived from the post glacial population (3). While no evidence exists for this, the origin of the Killarney population is still unknown.

Red Deer Stag, Cervus elaphus

The Red Deer can mate with its close relative the Sika Deer (Cervus nippon), an animal introduced to Co. Wicklow in 1860 (Powerscourt Estate) and then to Co. Kerry (4). While such hybridisation can impart new levels of fitness to a population (5), in this case preservation of the 'pure' stock of Red Deer is of paramount importance (6). Recent investigations into the levels of hybridisations in the Irish Red Deer population using microsatellite and mitochondrial DNA markers found that of 85 Red Deer tested, 10 were found to be Red/Sika hybrids with the other 75 being 'pure bred' individuals (6). While these levels of hybridisation were lower than expected, steps should be taken to prevent contact between the two species, with recommendations including culling of Sika stags entering Red Deer strongholds (7).

Reference:

1. Woodman et al., 1997 Quaternary Science Review 16 pp. 129–159
2. Moffat, 1938 Proceedings of the Royal Irish Academy 44B pp. 61–128
3. Staines et al., 2008 Mammals of the British Isles (Harris and Yalden, Eds.) pp. 573–587
4. Powerscourt, 1884 Proceedings of the Zoological Society of London pp. 207–209
5. McDevitt et al., 2009 Molecular Ecology 18 pp. 665–679
6. McDevitt et al., 2009 Mammalian Biology 74 pp. 263–273
7. Perez-Espona et al., 2009 Mammalian Bilogy 74 pp. 247-262

Clay Tablets, Eclipses and iPhones

A guest post by Ken.

I rose early last Tuesday morning, eager to get a glimpse of the partial solar eclipse. It is indeed an unusual world that we live in, with the natural world mixing with the artistic and the technological world combining both. I had to make my way to the strand in Carrigaline, groggy in mind as well as in spirits. The clouds were all about, the sun not yet risen and not about to show its face even when it did.

I waited from about 8.45am to approximately 9am. The horizon, although lined with forest-covered hills, would have afforded me a beautiful view of the eclipse if it were not for the clouds. My iPhone steadily pumping out the latest Kanye West hip hop tunes, and me waiting for the sun. I had just about given up and was making my way back home when for no reason at all I turned and a break in the cloud showed me a magnificent sight. My first sunrise of the new year 2011 and an opportunity for a partial eclipse event. Of course I had not brought my eclipse viewing glasses. A closed fist would have to do, peeping through it ever so slightly and finally sighting the sun, the orange disc on which all life depends, with a bottom-left portion of it missing, eclipsed by the moon. I was delighted. I even turned off the tunes and tried to snap a picture and although not much is visible this was at least a record of the event.



Partial Solar Eclipse over Carrigaline Strand

 The coincidence in size of the apparent diameters of the Moon and Sun produces a startling event at the Earth's surface which has held mankind in awe. Many civilizations [Babylon, China, Arab dominions, Europe] have recorded these events on clay, parchment or paper and some have survived to today. In fact these records are the only way known of measuring the actual changes in the Earth's rotation over the course of the ancient recorded history. (1)

Solar Eclipse

The clouds gathered again after 10-15 minutes and they decided that that was all I would see. I was glad I had seen that much. We shall not have another one until 2015 in these parts.

Later,

Ken.


References:

1.  L. V. Morrison, F. R. Stephenson, Historical eclipses and the variability of the Earth's rotation, Journal of Geodynamics, Volume 32, Issues 1-2, August-September 2001, Pages 247-265

Feeding Challenges for the Oystercatcher

Oystercatcher, Haematopus ostralegus

The Oystercatcher (Haematopus ostralegus, the Eurasian or Pied Oystercatcher) is one of the largest, and most striking wading birds in Ireland. A resident here all year round, it tends to stick to undisturbed shores when breeding, but is readily visible outside of this time on beaches and estuaries where large flocks often roost (1). It is plover in shape, but has a distinctive black and white colouring with long pink legs and piercing red eyes. Its stout yellow bill is used to feed on molluscs (predominantly mussels, despite its name) and shows three distinct shapes: pointed, chisel shaped and blunt (2).
Feeding can be quite an ordeal for the Oystercatcher. To begin with, there is stout competition for food to deal with. While the different bill types helps to reduce interspecific competition (2), dominance hierarchies exist at feeding sites where intake by subdominant individuals decreases with increasing bird densities (3). Dominant individuals at these sites suffered no such decrease. Feeding can be further restricted by shortened foraging times due flooded feeding areas. The Oystercatcher has been shown to be more than capable of meeting this challenge. In simulated shorter foraging times, birds spent proportionally more time foraging, shortened their searching time per prey item taken and decreased the time spent handling prey (4). This resulted in no decrease in consumption.

References:

1. Sterry, 2004 Collins Complete Guide to Irish Wildilfe p. 50
2. Swennen et al. 1983 Netherlands Journal of Sea Research 17 pp. 57-83
3. Ens and Goss-Custard, 1984 Journal of Animal Ecology 53, pp. 217-231
4. Swennen et al., 1989 Animal Behaviour 38 pp. 8-22

The Shoveler's Bill

Male Shoveler Duck, Anas clypeata

The Shoveler Duck, Anas clypeata, is a distinctive winter visitor to Ireland, migrating here from France, northern Europe, the Baltic, Russia and even a small population from Iceland (1), with some all-year residents. Both males and females are similar in colouring to its relative the Mallard (A. platyrhynchos), the females being a similar brown colour and the males having a green head and chestnut breast (but with blue forewings) (2), yet are quite different in one dramatic feature: their bill. The bill of the Shoveler is a large, spatulate tool it uses to filter feed aquatic plants and invertebrates (3). A. clypeata moves its bill from side to side as it passes through the water, filtering it as it goes.

Female Shoveler Duck, Anas clypeata, feeding

References:

1. Arzel et al., 2006 Journal of Ornithology Volume 147 pp. 167-184
2. Hayman and Hume, 2002 The Birdwatcher's Pocket Guide to Britain and Europe
3. Kooloos et al. 1989 Zoomorphology Volume 108 pp. 269-290

Forestry and the Fir Clubmoss

Fir Clubmoss, Huperzia selago

There are five native Clubmoss and Lesser Clubmoss (Spikemoss) species in Ireland, four of which have ever been recorded in County Cork: Fir Clubmoss, Lesser Clubmoss, Stag's Horn Clubmoss and Marsh Clubmoss. Of these, Fir Clubmoss (Huperzia selago) is by far the most frequent in County Cork and in Ireland as a whole (1). It is found on mountainous grassland, heath, moorland and rocky out crops (2). H. selago gets its common name from its resemblance to a small conifer. The plant consists of green, needle like leaves arranged around the stem. It produces spores, not in 'clubs' or cones as in other Clubmosses, but in small structures known as gemmae on the leaf axils. 

Fir Clubmoss, Huperzia selago

However, O'Mahoney has noted (1) that increases in forestry in upland areas poses a threat to H. selago. Its relatively slow growing pace means that recovery may often be impossible if displaced from an area.

References:

1. O'Mahoney, 2009 Wildflowers of Cork City and County p. 327
2. Phillips, 1978 Grasses, Ferns, Mosses and Lichens of Great Britain