In the previous blog (What are Non-native (or alien) Species?) I talked about non-native species and how they are transported around the planet. In this blog I’ll tell you a bit more more about rafting bivalves that can cross the Atlantic on plastics and about some of the UK hotspots for these non-native (alien) hitchikers.
What is rafting?
Rafting has occurred throughout geological time, and it is how many terrestrial (land-dwelling) species colonised islands and other regions across the seas. A good example of this is the lemurs of Madagascar. 60 million years ago there were no lemurs on the island of Madagascar, but their ancestors were on the mainland of the African continent. So how did they actually get to Madagascar? Palaeontologists tell us that rafting is the answer. Back then, Madagascar was closer to the mainland and currents in the Mozambique Channel were much stronger towards the island than they are now. The lemurs’ ancestors must have found their way onto mats of vegetation or branches and by chance rafted to Madagascar. A completely fluke event!
Today, our litter ends up in the oceans and provides unnatural vehicles for marine non-native species. Over the last decade more than 20 species of Caribbean bivalve shells have ended up on British and Irish beaches attached to plastic buoys, bait buckets, ropes and others items – even a piece of a car running board! The latter had three different types of Caribbean bivalves attached, one of which, the Bicolor Purse Purse Oyster, is an invasive species in Brazil. Violent storms help to throw the plastic objects high onto our shores and they are then found by beach cleaners, beachcombers and others on the strandline at the top of the beach. Many of the shells or photographs are sent to Amgueddfa Genedlaethol Caerdydd - National Museum Cardiff to be identified and hence to work out where they came from.
Conveyor belts and hotspots
The rafting species that we are studying start off attaching to plastics in the Caribbean. These plastics eventually float into the warm ocean currents of the Gulf Stream, which originates in the Gulf of Mexico, and provides a conveyor belt to transport non-native species across the Atlantic Ocean to the British Isles. Once here, violent storms then deposit the plastics, with their hitchhikers still attached, onto our shores.
The hotspots for non-native species records are in the southwest of England and western Ireland, but there are also records for western Scotland. Strangely enough there are no records for Wales, even though some of the beaches are prime, exposed shores similar to those in Ireland and England.
I want to discover if there are any welsh hotspots for rafting bivalves, find out which beaches to search and to encourage people to go out to those locations to try and get some records for Wales.
Why should we monitor these species?
It is important to establish points of entry for any non-native species, which is why we need to map where the rafting species are arriving so that we can monitor numbers of any species arriving alive that could possibly pose a threat. When a species moves to a new location, the species that already live there have to adapt to cope with the newcomer. This can put a strain on populations that use the same food source or habitat as the invading species, which is why we want to know where these rafting species are washing ashore. All the rafting species that we’ve encountered so far cannot reproduce in our waters as they need warmer sea temperatures of 20°C or more to breed. However, if sea temperatures continue to rise, climate change could aid more rafting species to create self-sustaining populations here which could become a real problem
The Bicolor Purse Oyster – an invasive species in Brazil
Of the non-native rafting species found so far in the UK, the Bicolor Purse Oyster (Isognomon bicolor) is the one that has shown up in the greatest numbers. It was first described as a species in 1846 by C.B. Adams who collected it in Jamaica. It has been spotted around the coasts of Florida, Texas and Bermuda and several of the Caribbean islands all of which are considered its natural range. However, in 1970 it was recorded outside its natural range in the eastern state of Rio Grande do Norte in Brazil. It has since moved further southwards and is considered an invasive species in Brazil as it is competing with native oysters and mussels for space and is spreading quickly.
The Bicolor Purse Oyster in Britain and Ireland
The Bicolor Purse Oyster has been found in Cornwall, Dorset and western Ireland by eagle-eyed beachcombers. They noted locations, objects that the oysters were attached to, and they collected the shells. The beachcombers are great photographers so we have a record of the variety of sizes, shapes and colours of the shells found here. The Bicolor Purse Oyster is small (up to 28mm), flattened and elongated. The outside is beige and white, sometimes with purple blotches and is smooth apart from being a bit flaky-looking. The front of the shell has byssus threads of pale to dark brown that protrude ready to attach to hard surfaces. In its natural range this species attaches to rocks and is commonly found in the Florida Keys.
What next?
Although there are lots of records of rafting species in Ireland and England, there are none for Wales. Does that mean that they do not wash ashore in Wales? Doubtful! This is why I’ve set up a project to get people out onto beaches looking for any plastics that could be likely rafts. The project involves citizen scientists – volunteers from the general public – who can help to spot these rafting species in Wales.
To find out more about this part of the project see next week's blog entitled Rafting Bivalves - the Citizen Science project.
As humans transport goods all over the planet we also unintentionally transport animals and plants to places that they do not belong. We call these animals and plants non-native or alien species. If conditions are right for the non-native species they can become established and outcompete our own native species for food and habitat. This is when they are called invasive species and could have a negative impact on our native species sharing the same habitat. This is bad news considering all the other pressures on our wildlife.
How do they travel such great distances?
One of the major transporters of marine non-native species are the large goods ships that travel from one side of the planet to the other, taking on ballast water in various ports and ejecting the water at their destination. Ballast water aids the huge ships to balance. At ports, as containers are removed from the ship, ballast water is taken on to keep the whole vessel evenly balanced. The problem is that the water in ports often contains tiny floating animals that are the offspring (or larvae) of mussels, crabs, clams and other invertebrates. These larvae get sucked into the ballast tanks and survive onboard until ejected at the destination port, which is sometimes on the other side of the planet. These animals would not normally have reached these far off destinations naturally.
Aquariums and aquaculture, or the farming of aquatic plants and animals, are another two major contributors towards the invasive non-native species spread. Shellfish farms import juveniles to grow and breed from but these can often escape captivity or have other species attached to them. The Manila clam (Tapes philippinarum) from the Indo-Pacific region was introduced for farming in the south of England in 1989, but has since escaped! Of all mollusc farming in the world, the Manila clam makes up an astounding 25% and this is because the species can grow quickly and reproduce in great numbers. It is also very hardy and has started to spread in the south of England and is breeding with one of our own native species. To learn more about Invasive Non-Native Species (INNS) in Wales check out the Wales Biodiversity Partnership INNS pages.
A third, less well-known method of transportation of non-native species is by rafting – or attaching to floating items. Numerous bivalves (eg. mussels, cockles, oysters) have crossed the Atlantic Ocean attached to bait buckets, buoys, crates and other sturdy plastic items. They wash ashore usually after particularly violent storms and are then stranded with the rest of the marine litter. We call these bivalves ‘rafting bivalves’. They attach to their ‘raft’ using byssus threads or cement, depending on the kind of bivalve. Byssus threads are produced by a special gland in the foot of the animal to allow the shell to anchor onto hard surfaces such as rocks. You may have seen this with mussels on our rocky shores. Oysters and other similar bivalves use a special cement to glue themselves onto hard surfaces and so they are also able to attach to the plastic rafts. I am especially interested in learning more about marine bivalve shells that attach to ocean plastics and then wash ashore on our beaches and have started to add them to our Marine Bivalve Shells of the British Isles website.
To find out more about Rafting Bivalves check out next week's blog.
Ming is an Ocean Quahog clam with the scientific name of Arctica islandica. It was nicknamed Ming when scientists discovered that it would have been born in 1499 during the Ming Dynasty of China. Ocean Quahogs grow up to 13 cm long and the oldest one fished off the coast of Iceland was 507 years old, making it the oldest non-colonial animal known to science.
Where do Ocean Quahogs live?
Ocean Quahogs belong to a big group of shells called ‘bivalves’. Most bivalves are filter feeders and suck in water through their tube-like siphons (you can see in the photo, the two holes surrounded by darker pink). While lying on the seabed or buried in the sand or mud bivalves can safely take food particles and oxygen from the water.
Ming was collected from the deep waters around Iceland but we get this species in British and Irish waters too, although it does not live to such a great age here. The waters surrounding our islands are warmer than those surrounding Iceland, which is just south of the Arctic Circle. Warm waters hold less dissolved oxygen than cold water and so around the UK the Ocean Quahog needs to work harder to get oxygen and so has a faster metabolism. A faster metabolism means that it grows quicker but when animals have a fast metabolism they do not live as long. In the colder waters surrounding Iceland the Ocean Quahog has a slower metabolism and so grows slowly and may even live for longer than 507 – scientists just haven’t found an older one yet!
How long do animals live?
Some other bivalve molluscs can live for a long time as well. Giant clams can grow to 4 feet long (1.2 m) and live for around 100 years. They have tiny plant cells in their tissue that photosynthesize producing energy from the sun to give to the clam. This is why they reach such a large size – talk about plant power!
The Geoduck, which lives in the coastal waters of western Canada and USA, can live for 164 years. It is known as Gooey duck and has large meaty siphons that are a popular food for humans!
Come to our Insight gallery at Amgueddfa Genedlaethol Caerdydd - National Museum Cardiff to to find out more about how long animals can live for and much more...
An introduction to Ming the clam can be found here:
At 507 years of age Ming the clam broke the Guinness World Record as the oldest animal in the world. Collected off the coast of Iceland in 2006, initial counts of the annual rings of the shell put the age at around 405 years old, which was still a record breaker. However, in 2013 scientists re-examined the shell using more precise techniques and the count rose to 507 years old.
This is what remains of the actual shell that was used in the aging study. At 507 years the Ocean Quahog is the oldest non-colonial animal in the world. We say ‘non-colonial’ because some animals such as corals can live to over 4,000 years but they are made of lots of animals (called polyps) stuck together as a collective form. Of the animals that exist alone the Ocean Quahog is the oldest and the Greenland Shark comes in second at around 400 years old.
If you’d like to see Ming face-to-face (well, shell-to-face!) and find out how scientists discovered Ming’s age then come to Amgueddfa Genedlaethol Caerdydd – National Museum Cardiff and visit our Insight gallery. As well as learning about Ming you can find out about Freshwater snails, prehistoric mammals and lots more....
Dippy yw ein henw ni ar y sgerbwd deinosor hoff, ac rydyn ni’n gwybod fod ganddo hanes diddorol. Ond ai Diplodocus fu’r enw ar y ffosilau yma erioed? Wel, na, mae hynny'n annhebygol...
Rydyn ni wedi clywed sut y daeth 'Dippy' i Lundain ym 1905 yn gast plastr o'r esgyrn ffosil gwreiddiol yn Amgueddfa Carnegie, Pittsburgh. A, diolch i balaentolegwyr, gallwn ei ddychmygu'n anifail byw yn pori coedwigoedd Jwrasig, 145-150 miliwn o flynyddoedd yn ôl, yn diogelu ei hun rhag ysglyfaethwyr gyda'i gynffon chwip.
Ond beth am weddill y stori? O ble ddaeth y ffosilau hyn?
Ym 1898, diolch i'r diwydiant dur, Andrew Carnegie oedd un o'r dynion mwyaf cyfoethog yn y byd. Roedd yn brysur yn rhoi ei arian i lyfrgelloedd ac amgueddfeydd. Pan glywodd am y deinosoriaid anferth oedd yn cael eu darganfod yng ngorllewin America, dywedodd rywbeth fel “Dwi eisiau un o rheina!” ac anfonodd dîm o Amgueddfa Carnegie i chwilio am yr “anifail mwyaf anferth yma”.
Felly, ym 1899, yn nyddiau olaf Hen Orllewin America, cafodd sgerbwd Diplodocus ei ddarganfod yn Sheep Creek, Albany County, ar wastadeddau Wyoming. Y dyddiad, fel mae'n digwydd, oedd 4 Gorffennaf, Diwrnod Annibyniaeth America. Ac felly y cafodd y ffosil ei lysenw cyntaf gan dîm Carnegie, 'The Star Spangled Dinosaur'. Ond, ymhen hir a hwyr, cafodd y rhywogaeth newydd hon ei chyhoeddi yn swyddogol fel Diplodocus Carnegii.
Byddai safle'r cloddio wedi edrych yn debyg iawn i'r safle tebyg yma gerllaw yn Bone Cabin Quarry, yn yr un flwyddyn.
Mae'r lluniau yma o ddiwedd y 1800au o rannau eraill o Albany County, Wyoming, yn ein helpu i greu darlun (o Wikimedia Commons).
Enw cyntaf Dippy, 'Unkche ghila'
Ond beth am frodorion y gwastadeddau? Oni fyddai'r brodorion wedi darganfod ffosilau deinosor cyn y gwladychwyr Ewropeaidd? Yn ei llyfr, Fossil Legends of the First Americans, mae Adrienne Mayor yn dangos y gwnaethon nhw. Dychmygodd y brodorion ffurfiau gwreiddiol y ffosilau fel Madfallod Anferth, Adar y Taranau a Bwystfilod Dŵr, ac roedd sawl un o'r casglwyr deinosoriaid enwog yn dewis brodorion yn dywyswyr. Mae'r llyfr yma'n dangos fod y brodorion wedi sylwi ar y prosesau daearegol fel difodiant, llosgfynyddoedd a newid yn lefel y môr a’u bod yn sail i’w credoau am ffosilau.
Y Lakota Sioux oedd brodorion y gwastadeddau lle cafwyd hyd i ffosilau Diplodocus. Ganwyd James LaPointe, pobl Lakota, ym 1893. Dyma hanes a glywodd pan yn fachgen:
“Roedd y Sioux yn galw'r creaduriaid hyn, sy'n cymharu'n fras â deinosoriaid, yn 'Unkche ghila'. Roedd y creaduriaid siâp rhyfedd yn crwydro'r tir mewn grwpiau mawr, ac yna'n diflannu. Mae esgyrn anferth y creaduriaid hyn, sydd bellach wedi diflannu, yn nhiroedd garw de a dwyrain y Bryniau Du. Dyw e ddim yn glir os wnaeth yr unkche ghila ddiflannu, ond mae daeareg y Sioux yn nodi eu bod yn dal i fod o gwmpas pan gododd y Bryniau Du o'r ddaear."
Felly, trwy law Adrienne Mayor, dyma roi'r gair olaf i Wasanaeth Parciau Cenedlaethol yr UDA:
"Mae straeon a chwedlau'r brodorion yn cynnig persbectif unigryw i arwyddocâd ysbrydol traddodiadol ffosilau ac yn gyfle heb ei ail i ddangos y cysylltiad anhepgor rhwng pobl a natur." Jason Kenworthy a Vincent Santucci, A Preliminary Inventory of National Park Service Paleontological Resources in Cultural Resource Contexts.
