Beef or Salmon? Prawns please!!!

A guest post by Ken.

The common prawn (Palaemon serratus) is found on rocky shores around Ireland. They are often trapped in rock pools at low tide but can be difficult to spot due to the transparent body but become visible when moving. A closer look reveals purplish-brown dots and lines on its body. Their antennae are very long and a toothed rostrum extends forward between the eyes. It uses its fan like tail to swim backwards if alarmed. Has a diet mainly of scavenging. (1)

Common Prawn (Palaemon serratus)

Lovell et al. performed a study on P. serratus using a combination of anatomical, electron microscopic and electrophysiological approaches involving the statocyst. In crustaceans, the statocyst is found either at the anterior end of the animal in the basal segment of each antennule, or posteriorly within the uropods, abdomen or telson. It has been known that the statocyst is used as an equilibrium organ to orientate the animal within the water column. This study used an ABR (Auditory Brainstem Response) type investigation to determine the prawns hearing abilities. To acquire an ABR waveform conglomerate responses of peak potentials are averaged, which arise from nuclei in the auditory pathway during acoustic stimulation. This work provided conclusive evidence of low-frequency sound detection of frequencies ranging from 100 to 3000 Hz (a hearing acuity similar to that of a generalist fish) by a member of the sub-phylum crustacea. For hearing ability to be attributed to an organism, the physiological response sound should be initiated by a specialised receptor mechanism and here it was shown to be generated in the statocyst. In addition, recorded neural waveforms were shown to be similar in both amplitude and shape to those from fish and higher vertebrates, when stimulated with low-frequency sound, and complete ablation of the electrophysiological response was achieved by removal of the statocyst. (2)

References:

1. Sterry 1997, Collins Complete Guide to British Wildlife p. 216
2. Lovell et al. 2005, Comparative Biochemistry and Physiology, Part A 140 pp.89-100

Sniping About the Weather

Snipe, Gallinago gallinago, feeding

The Snipe (Gallinago gallinago) is an unmistakable bird, most commonly seen in Ireland in winter when resident numbers are swelled by migrant populations from northern Europe (1). Its is similar in shape to the Woodcock and the Jack Snipe, but its size and the yellow bars on its head and down its buff-brown plumage make it easily recognisable (2). It inhabits wetlands and moors where it uses its almost disproportionally long bill to probe the mud for invertebrates. This it tends to do alone, although small groups are sometimes seen foraging together.
While there has been a decline in numbers of Snipe over the past 30 years (3), the species is so numerous that the International Union for Conservation of Nature sees it as of least concern (4). The situation may become critical however due to continued destruction of wetland habitats by draining and further intensification of grassland management (5). Most grassland systems in Ireland lack botanical diversity, being composed typically of just a handful of ryegrass species (6). This results in a lack of invertebrate numbers and development of impenetrable rhizosphere areas, making feeding for the Snipe almost impossible (7).
Habitats where feeding is easy due to wet or waterlogged soil lead to longer nesting times for Snipe (5), and while wet weather does provide this increase in feeding ability, it also brings the problem of flooding. Flooding has been shown to delay Snipe nesting by up to 70 days, suggesting they are quite weather dependent breeders.

References:

1. Sterry 2004, Collins Complete Guide to Irish Wildlife p. 60
2. Hayman and Hume 2002, The New Birdwatcher's Pocket Guide to Britain and Europe p. 117
3. Henderson et al. 2002, Bird Study 49 pp. 17-25
4. www.iucnredlist.org/apps/redlist/details/150697/0
5. Green 1988, Journal of Applied Ecology25 pp. 79-93
6. Byrne 2009, Euphytica 166 pp. 61 – 70.
7. McCracken and Tallowin 2004, The International Journal of Avian Science 146 pp. 108-114

Putting the Moss in its Box

Moss classification is tough. To the casual observer there is very little to differentiate one patch of green in the undergrowth from another. Closer inspection reveals that, while there are certainly distinct groups, identification to the species level is an arduous task in some cases. Mosses' fruiting bodies provide something of an answer. The eminent Finnish bryologist Viktor Ferdinand Brotherus (1849 - 1929) was most influential in introducing classification based on moss peristomes, the structures in the fruiting bodies that regulate spore release (1). This poses problems however as these structures, by their very nature, are exposed to the vagaries of the elements and may lead to incorrect classification. Molecular characters are becoming more and more popular for moss taxonomy, however single-gene classification systems are just as likely to be faulty as any other type of single character classification, and therefore caution is needed (1). A combination of techniques is often needed.

Hart's Tongue Thyme Moss, Plagiomnium undulatum

One of these is the use of the karyotype (number and appearance of chromosomes in the cell) of the moss species. Bowers (2) used this cytological approach to re-classify some members of the family Mniacea. Species of one genus in this family, Plagiomnium, are especially difficult to separate morphologically. In once species, P. undulatum (Hart's Tongue Thyme Moss), cytology revealed variability in karyotype formula and chromosome set length, but a high uniformity of chromosome number (3). P. undulatum is common in damp, shaded places and is notable for its long stems, which may grow to 10 cm in length (4). Male and female structures are borne on different plants with the male forming rosette like structures as seen in the example pictured.

References:

1. Buck and Goffinet 2000, Bryphyte Biology (eds. Shaw and Goffinet) pp. 71-123
2. Bowers 1980, Lindbergia 6 pp. 22-31
3. Przywara et al. 2003, Acta Biologia Cracoviensia, Series Botanica 45 pp. 105-110
4. Phillips 1980, Grasses, Ferns, Mosses and Lichens of Great Britain and Ireland p. 133

Don't Eat the Jelly

Commonly called Jelly Fungi, the Heterobasidiomycetes are a comparitvely small group of fungi that differ from other Basidiomycetes in the structure of the basidium (1). The origin of their common name is self evident, their jelly-like appearance coming from the gelatinous structure of the fruiting bodies. These have a considerible capacity to withstand dessication.

White Brain Fungus, Exidia thuretiana

A common Jelly Fungus, often seen in large groups on dead and rotting branches of broadleaf trees (especially beech) is the White Brain Fungus, Exidia thuretiana. When wet, E. thuretiana appears cushion-like. It becomes contorted into brain-like folds, fusing with adjacent fruiting bodies that are smooth, shiny and white (1). Upon drying, it shrinks and becomes quite hard with smaller specimens becoming almost invisible. Odorless and tasteless it is inedible, appearing in autumn and winter.

Dacrymyces stillatus

Similarly inedible, Dacrymyces stillatus is yellowish orange when wet, becoming a deeper orange when dry. It is most common in the late summer to early autumn when the sub-spherical to saucer shaped frutiing bodies appear smooth and glistening (1). It can caused considerable decay of both broadleaf and coniferous wood (2).


References:

1. Jordan 1995, The Encyclopedia of Fungi of Britain and Ireland pp. 367, 369, 371
2. Seifert 1983, Mucologia 75 pp. 1011-1018

Ammonite's Feast

Ammonoid Fossil

Ammonites dominate marine fossils from the Late Silurian to the end of the Cretaceous, a period of 300 million years (1). Their abundance over this period of time has made them immensely important index fossils for dating Late Palaeozoic and Mesozoic rocks and for characterising various kinds of marine communities (2). The subgroup Ammonoidea, to which the ammonites (order Ammonitida) belong (along with Anarcestida, Ceratitida, Clymeniida, Goniatitida and Prolecanitida) appeared in the Early Devonian period and are classed as cephalopods, with extant members such as squid, octopuses and the nautiloids (3).

Despite their abundance in the fossil record, little is known about the paleobiology of ammonites due to the lack of a direct living counterpart and a lack of preserved soft tissue (4). However some light has been shed on their feeding habits in an intriguing study of the mouth of the Mesozoic ammonite Baculites using synchrotron x-ray microtomography (5). This method nondestructively generates three dimensional maps of the fossil using x-rays by building up cross sectional images(6). The images generated showed a tiny snail and three tiny crustaceans in one of the ammonite's mouth and jaws and a radula that were adapted for eating prey floating in the water suggesting that these ammonites fed on plankton. The research also suggests a reason for the decline and subsequent extinction of the ammonites around the Cretaceous-Tertiary extinction event as plankton were severely hit at this time.

References:

1. Parker 2007, The Complete Guide to Fossils and Fossil Collecting p. 168
2. Summesberger 1985, Annalen des Naturhistorischen Museums in Wien 87 pp. 145-166
3. Kennedy 1977, Patterns of Evolution as Illustrated by the Fossil Record (ed. Hallam) pp. 251-304
4. Tanabe 2011, Science 331 pp. 37-38
5. Kruta et al. 2011, Science 331 pp. 70-72
6. Flannery 1987, Science 237 pp. 1439-1444

A Wee Gem

Gem Anemone, Bunodactis verrucosa

The attractive Gem Anemone (Bunodactis verrucosa; also Aulactinia verrucosa) is a common inhabitant of well let rockpools and crevies. Its column bears lonitudinal rows of warts, from which its derives its alternative common name the Wartlet Anemone (1). Tentacles are in multiples of six, rarely being more than 48 giving a maximum span of 60 mm. Its wonderful hues of pink, green, red and brown are very appealing but, when combined with the transparency of parts of the tentacles, provide excellent camouflage against the background rockpool flora of encrusting corraline algae. While it reproduces by viviparity, asexual reproduction by budding has also been observed (2). B. verrucosa also has been shown to have excellent regenerative capabilities and has been used as a model to study coelenterate regeneration (3).

References:

1. Chinery 1999, A Beginner's Guide to Irelands Seashore p. 83
2. Perrin 1999, Oceanography and Marine Biology: an Annual Review 37 pp. 129–152
3. Shostak 1983, Development Genes and Evolution 190 pp. 274-282

Shooting the Teal

The Teal (Anas crecca) is Ireland's smallest duck (34 - 38 cm in length) most likely to be seen as a winter visitor from September to April, although there is a small breeding population in the country (1). An attractive little bird, the male has a dark brown head with a yellow bordered green patch through the eye, a grey body and a black edged, triangular patch in front of the black stern (2).

Male Teal, Anas crecca

The Teal is also attractive to hunting enthusiasts too, leading to a certain amount of lead shot in birds. A 21 year study of Teals in southern France showed that lead shot was more likely to be found embedded in male birds over females and there was an accumulation over time with no adverse effects (3). The same could not be said for lead found ingested in the gizzard of Teals. More likely to be found in females over males, as little as one piece of lead shot is toxic once ingested by foraging birds. Moreover, lead poisoning accumulates in ecosystems, with posioning being reported in in 17 higher predators in Europe such as the near threatened White Tailed Eagle of the endangered Spanish Imperial Eagle (5), strengthening calls for tighter regulation of lead shot usage.

References:

1. Sterry 2004, Collins Complete Guide to Irish Wildilfe p. 40
2. Hayman and Hume 2002, The New Birdwatcher's Pocket Guide to Britain and Europe p. 38
3. Guillemain 2007, Biological Conservation 137 pp. 567-576
4. Mateo 2009, Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans, Watson et al. eds. pp. 71-98

Sea Spleenwort Likes the Rain

Sea Spleenwort, Asplenium marinum

Sea Spleenwort, Asplenium marinum, is a common fern found in rock crevices through out the coasts of Ireland (1). As such, it is exposed to highly saline conditions which can delay spore germination and even prevent it completely at high concentrations (2). However, once a decrease in salt concentrations occurs, due in vivo to rainfall, spores regained their germination ability.

Sea Spleenwort, Asplenium marinum

References:

1. Philips 1980, Grasses, Ferns, Mosses and Lichens of Great Britain and Ireland p. 97
2. Pangua 2008, Flora - Morphology, Distribution, Functional Ecology of Plants 204 pp. 673-684

Trichoptera, the Caddisflies

Black Dancer Caddisfly, Mystacides azurea

The Caddisflies, or Trichoptera, are present in large number on every continent bar Antartica but are relatively unknown to the general public. Outside experts, anglers are the only people who know the insects. Caddisflies are a very important food for predators such as fish and anglers imitate them with artificial lures (1). Ignorance of these small (the largest being c. 30mm (2)) insects is understandable as they are tied to water for most of their lives. The eggs, larvae and pupae are found in or very near fresh water and the adults, while aerial, are rarely found far from streams and rivers (1). It is surprising therefore to discover that surveys of streams often see more species of caddisfly than mayflies, dragon- and damsel flies and stoneflies (3). Indeed in Ireland there are more species of caddisfly, 147, than of the other three orders combined, 100 (4).

Caddisfly Larval Cases

The diversity of caddisflies has been attributed to the ecological opportunities made possible by the secretion of silk (3). Silk is used by caddisflies for a variety of uses, such as spinning catching nets and hiding tubes, construction of small domes from sand grains,using silk to stick together pieces of plants and other materials into protective cases and the spinning of cocoons (5). Such activities are carried out prior to the emergence of the adults that resemble small moths, to which they are closely related (1). They differ in that their wings are covered with hairs rather than scales (6). The diversity of caddisflies is such that they are used in palaeoecology to investigate phenomenon such as the effect of long term climate change (7).

References:

1. Morse 2009, Trichoptera (Caddisflies) in Encyclopedia of Insects pp. 1015-1020
2. Chinery 1997, Collins Gem Insects p. 212
3. Mackay 1979, Annual Review of Entomology 24 pp. 185-208
4. Ferriss et al. 2009, Irish Biodiversity: A Taxonomic Inventory of Fauna pp. 96-111
5. Sehnal and Sutherland 2008, Prion 2 pp. 145-153
6. Holzenthal 2009, Encyclopedia of Inland Waters pp. 456-467
7. Williams 1988, Palaeogeography, Palaeoclimatology, Palaeoecology 62 pp. 493-500

River Builders

Flowers of the Branched Bur Reed, Sparganium erectum

Riverside plants have long been recognised for their ability to provide food and shelter for a range of animals – overhanging willows create ideal nesting sites for Moorhens, Water Mint and the many flowered Purple Loosestrife, among others, provide a food source for insects. It is now recognised that riverside vegetation does more than just influence species composition. They directly engineer landform development along river margins. For example by trapping sediment plants can change the unit stream power (1). In some cases, when trees are involved, this can lead to the creation of river islands (2).

Branched Bur Reed, Sparganium erectum

However it is not just trees that are capable of engineering rivers. The Branched Bur Reed (Sparganium erectum) is an emergent, sedge like perennial of still and slow moving fresh water and is common in northern temperate areas (3). It is currently being assessed for its ability to accelerate channel adjustment in low energy river systems (4). The plant acts by retaining finer sediment, organic matter and plant propagules which is held in place as the plant grows. This then allows the plant propagules to germinate, leading to the appearance of new species, which in turn promotes further retaining of sediment, resulting in landform construction.

Fruit of Branched Bur Reed, Sparganium erectum

References:

1. Gurnell et al. 2010, Geomorphology 116 pp. 135-144
2. Gurnell and Petts 2006, Earth Surface Processes and Landforms 31 pp. 1558–1574
3. Sterry 2004, Collins Complete Guide to Irish Wildilfe p. 270
4. Gurnell et al. 2010 Geophysical Research Abstracts 12 EGU2010-5883

Bacterial Associations of Cladonia pyxidata

Cladonia pyxidata

Lichens are a wonderful example of symbiosis in nature, often quoted to biology students as a relationship where both partners benefit from a very close association. However there may be more than just the two partners in these marriages of fungi and algae. Analysis of bacterial communities on lichen thalli found species that may provide nitrogenous compounds to the lichen and may even help protect the lichen (1). The lichen Cladonia pyxidata, found in degraded, peaty habitats (2), was found to have Burkholderia spp. on its thalus, bacteria that have been shown to have antifungal properties. This may provide some degree of protection to C. pyxidata.

References:

1. Cardinale et al. 2006, FEMS Microbiology Ecology 57 pp. 484–495
2. Aptroot et al. 2001, The Lichenologist 33 pp. 271-283

A Warm Spring Suits the Greenshank

Greenshank, Tringa nebularia

The Greenshank (Tringa nebularia) is a winter migrant to Ireland, arriving in September to estuaries all along the coast and returning to Scandinavia and Scotland in April (1). The individual pictured is showing its winter colours; in the summer they have a grey breast and darker above (2). The breeding performance of this species of sandpiper is very much influenced by weather conditions. In a 19 year study on a population of Scottish Greenshank, it was seen that, among other observations, warmer weather in the early spring resulted in larger eggs and heavier chicks, as well as more successful hatchings (3). Bad conditions over two successive years resulted in fewer birds returning to bread and the establishment of fewer new territories.

Greenshank, Tringa nebularia

References:

1. Nethersole-Thompson and Nethersole-Thompson 1979, Greenshanks
2. Hayman and Hume 2002, The New Birdwatcher's Pocket Guide to Britain and Europe p. 106
3. Thompson et al. 1986, Journal of Animal Ecology 55 pp. 181-199

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