For several years we have taken the students on the Mallorca field-course to the strand-line along the Bay of Pollensa and the dune system near C’an Picafort. Both of these stretches of beach tend to collect odd, fuzzy balls of Neptune’s grass (Posidonia oceanica). Wave action breaks down the dead leaves and rhizomes of Neptune’s grass creating fibres which then become matted into dense spheres. I’ve written a previous blog post about Neptune’s grass on these shores of Mallorca.
Instead, this year we visited a different part of the coast where the material accumulates in sculpted waves along the beach edge. Previously I’ve seen this from the window of the coast, so it was interesting to experience it first hand. It is very soft, prone to collapsing and makes the shore edge difficult to walk on. There must be something different about the coastline here which makes the formation of the fibre balls less likely. Whether in balls or loose, the dried Neptune’s grass adds organic matter to the sand and helps to stabilise the dunes further up the beach.
This bit of beach was at the Finca de Son Real, an example of a traditional land-holding now managed by the Balearic Government as a nature reserve and archaeological site. There is a museum here which gives an insight into the lives of the rural people of Mallorca. Through displays of objects, room reconstructions, audio and projections, the museum explores the site from and from neolithic times into the 20th century including an explanation of how local farmers would have collected dry Neptune’s grass to use as animal bedding.
For many years the students on the Comparative and Adaptive Biology field course in Mallorca have visited the strandline and salt marsh plant communities at the Albufereta Nature Reserve on the Bay of Pollença. This year, however, we went for a tour of the S’Albufera wetland (a Ramsar protected site of international importance) by Gaspar, one of the team who manages the reserve. The reserve has been protected since 1988 and is surrounded by the coastal tourist resorts and inland agricultural lands.
The land around the Bay of Alcudia is naturally marshy, with water from the seasonal rivers (torrents) held back by the sand bars at the coast. However, the marsh isn’t entirely fresh, but is brackish and salty in places as seawater infiltrates the sand to saturate the land behind. This winter was drier than average, leading to the marsh being saltier than usual for so early in the year. In the 19th century, the British civil engineer John Frederick Bateman carried out work to drain the marsh for agriculture, creating the infrastructure which is still visible today – a network of canals, ditches, bridges and old pumping houses. More recently the focus has been on retaining the water and so sluice gates have been added to maintain the wetland habitat for wildfowl. The reserve is a carefully managed mosaic of old reedbeds (dominated by Phragmites australis), open waters, scrapes and salt marsh. Horses are particularly important for managing the more open environments, keeping the reeds in check.
The human population around the reserve around 60,000, but over the summer season this can triple with the arrival of holidaymakers seeking some Mediterranean sun. This places a huge increase in demand for drinking water and wastewater treatment over the driest months in the Mediterranean. It is at these times when the reserve is at its most vulnerable from pollution (e.g. nitrates escaping from water treatment works) without the potential for a diluting influx of freshwater.
The wetland is used by some bird species all year round and by others who use it as a staging post on their migrations. With the background soundtrack provided by Cetti’s warblers, we watched black-winged stilts, avocets, egrets, a kingfisher, shelducks, crested coots and an osprey. Still, the zoological highlight happened later in the day as the flamingos treated us to a fly-by on the beach.
Yesterday saw a group of first-year undergraduates braving the baking Mediterranean sun for the first day trip of the Comparative and Adaptive Biology field course. The Bocquer Valley near the town of Pollenca is a great place to look for Mallorcan endemic ‘hedgehog’ plants Teucrium subspinosum and Astragalus balearicus. While the students investigated the distribution of these small spiny shrubs, the staff took the opportunity to do a little more plant hunting.
One beautiful plant we regularly see in flower is the Balearic cyclamen (Cyclamen balearicum). It has very marbled leaves and delicate white flowers and hides in the shade of the larger shrubs. We also find the leaves of the Mallorcan peony (Paeonia cambessedessii). We visit far too late to see it in flower, but we’ve never found fruit either, suggesting that these plants didn’t flower in February or March. Perhaps these are young plants, or perhaps this is an indication of the difficult environment in the valley. This peony is named for the French botanist Jacques Cambessedes (1799-1863) who studied the plants of the Balearic Islands in 1825 and published the account of his travels and his work on the flora in 1826 and 1827.
One plant we’ve not spotted on our previous visits is the Dead-horse arum (Helicodiceros muscivorus). Given that it was behind a tree, under a shrub and in the bottom of a drainage channel, it’s not too surprising that we’ve not found it before. This plant has striking arrow-shaped leaves (sagittate leaves) and a flower spike (spadix) enclosed in a sheath known as a spathe. This specimen had not yet opened, and the geometrically patterned spathe was still closed shut. I’m not sure that I was too disappointed as the plant attracts pollinating flies with heat and rotting carcass smells.
There’s still time for one final post before it’s time to say goodbye to the Mallorca field course for another year. With two orchid fans on the staff, it’s not surprising that a good few hours each day were spent orchid spotting, but this year we had an up-and-coming orchid specialist amongst the students too. Head over to the FrogBlog to check out Tom’s thoughtful account of his Mallorcan orchid-hunting experiences.
Earlier in the month Rachel went on a trip to Mallorca, with a group of 1st year undergraduates from the University of Manchester (for more information see her blog post: https://herbologymanchester.wordpress.com/2015/04/07/surviving-salt-and-waterlogging-on-the-albuferita-mallorca/). During her time there she saw a number of sea squills (Drimia maritima) so I thought I would write a post about this interesting plant.
Drimia maritima is a poisonous plant that grows in rocky coastal habitats across southern Europe, western Asia and northern Africa. It grows from a large bulb that can be up to 20 cm wide and a kilogram in weight. In the spring, the bulb produces a rosette of dark green, leathery leaves that can reach up to a metre long. The leaves die away by autumn, when a shoot containing the flowers grows from the bulb. This flower-bearing shoot can achieve a height of up to 2 metres. Pollination of the Drimia maritima flowers occurs by both insects (specifically the western honey bee, the Oriental hornet, and the paper wasp) and wind.
Drimia maritima has been mentioned as far back as the 16th century BCE in the Ebers Papyrus (an ancient Egyptian medicinal text). In the 6th century BCE the Greek philosopher Pythagoras wrote about the uses of squill and, along with Dioscorides (1st century ACE and author of De Materia Medica), recommended hanging the bulb to protect against evil spirits.
One of the earliest medical applications of the sea squill came from the Greek physician Hippocrates (4th century BCE), who advocated its use to treat jaundice (yellowing of the skin), convulsions and asthma. Over the centuries, Drimia maritima was used as a common treatment for dropsy (abnormal accumulation of fluid in tissues) before the more effective foxglove (Digitalis sp.) became the standard treatment during the 18th century. The plant has also been used in folk medicine as a laxative and to clear mucus build-up.
In addition to its medicinal use, squill has been employed as a poison. All parts of the plant contain toxic chemicals. Once such compound, called Scilliroside, was shown in 1942 to be an effective rodenticide that is avoided by most other animals. In the 20th century, Drimia maritima began to be experimented on to develop highly toxic varieties for use in rat poison. Though not the most common rodenticide, interest in squill’s rat killing abilities has increased dramatically since many rats became resistant to the coumarin-based poisons previously used.
It’s that time of year again when a lucky group of 1st year undergraduates from the University of Manchester head to the Mediterranean to learn about plant evolution and adaptations. This year in Mallorca we stopped at a slightly wetter part of the Albufereta, a small salt marsh near to the town of Alcudia (north-west of the lager famous wetland and Ramsar site, the Albufera). With more water in evidence, this part looked like a better place for the students to learn about mechanisms plants can use to tolerate salt stress.
The area is dominated by three plant species Arthocnemum macrostachyum (Glaucus glasswort), Halimione portulacoides (Sea purslane) and Juncus maritmus (Sea rush). Each of these has has specialised mechanisms for living in high salt, waterlogged soils such as succulent stems, the ability to exudes salt onto the leaves or air-filled spaces within the leaves and stems.
Patches of slightly higher ground, however, allowed other plants to grow, including this Grey birdsfoot trefoil (Lotus cytisoides). The weather had been a little cold over the preceding weeks and as this was one of the few plants in flower it was getting a lot of attention from the bees.
We see a lot of this plant on the strand-line and sand dune systems around Alucudia. It is clearly also salt-tolerant, but likes freer-draining soils and cannot cope with waterlogging. In flooded soils, air spaces fill up with water and bacteria rapidly use up available oxygen. Without special adaptations, plants in waterlogged soils can die as their roots are effectively suffocated as the flow of oxygen and carbon dioxide in and out of the roots is limited. Roots can then be invaded by fungi and other pathogens and the above ground parts of the plant suffer as water and nutrient transport from the roots is affected.
The University of Manchester has broken up for the Easter holidays and so it must be the right time of year again for the 1st year field course in Comparative and Adaptive Biology. This year the staff and students were even more enthusiastic than usual to escape the unseasonably cold snow flurries of Manchester and head for sunny Mallorca. We’ve been braving the mosquitoes in the shrubberies to study how plants cope with the challenges of Mediterranean living and to see some interesting examples of plant endemism.
Last year I blogged about one of our days on the seashore, so I think this time I shall go more terrestrial and share some images from a site which is one of the staff favourites. Although there are other places to go and see Holm Oak (Quercus ilex) woodland, the Bronze Age talayotic site of Ses Paisses is pretty special. Excavated in the mid 20th century, the settlement is arranged around a central tower (or talaiot) and is now covered by a very nice woodland.
Under the shade of the oak trees we find black bryony (Tamus communis), butcher’s broom (Ruscus aculeatus) and a hemi-parasitic plant Osyris alba which can produce it’s own sugars by photosynthesis but steals water and minerals from a host plant .
However, with all these rocks around there is always the chance that botanical lectures on the effects of light and shade can end up being disrupted by sudden acts of zoology….
Now there couldn’t be a finer way to listen to a lecture! These first-year undergraduate students from the University of Manchester are in Mallorca to learn about Mediterranean ecosystems and plant adaptations to the climate. On days like today it’s much easier to explain the challenges of the Mediterranean climate than on days when the rain is falling steadily. They also get to appreciate the view too; this view is out across the Bay of Pollensa where underneath the water there are large beds of seagrass called Posidonia oceanica or Neptune’s grass.
Although underneath the waves, it not a seaweed and is actually a flowering plant. It can produce fruits which float on the ocean, but it also spreads very slowly by creeping rhizomes. A recent study published in the journal Plos One has shown that these clonal meadows of seagrass could be thousands of years old.
Growing at depths of about 1-45m (depending on water clarity) these seagrass beds are very important ecosystems. These meadows trap carbon dioxide and release oxygen in coastal waters through photosynthesis, provide energy at the bottom of the food chain and act as nursery grounds for many fish and invertebrates. The environmental importance of this ecosystem is reflected by its protection as a priority habitat by the legislation of the EU Habitat Directive and by the programs aimed at conserving it.
These meadows also have important effects on the seashore. Debris is washed-up from below the sea and collects on the beaches, sometimes forming great sculpted ‘cliffs’ of plant material. These heaps of dead seagrass leaves and rhizomes are striking, but far more curious are the fibre balls which can also be found on some beaches. Wave action on the beach smashes up and wears away the tissue of the seagrass leaves, leaving only the leaf veins which get tangled up and moulded into these pebble shapes.
Which ever form the material ends up on the beach in, once there it helps to stabilize the shifting sands to build dunes, to retain water and to provide nutrients which allows plants to colonize the strandline. Plants such as this lovely yellow-horned poppy (Glaucium flavum) which sadly isn’t in flower yet.
Best go back to staring a that sunny view………..