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Falklands Conservation |
Falkland Lichens Richness on the Rocks
by Dr Kery Dalby
Dr Kery Dalby visited the Islands in January 2000 to study lichens. He collected 300 specimens representing some 100 species. He reports here on his findings from this intriguing group of plants.
The primary aims of my visit in January/February 2000 were to extend the lichen collections from the Falklands and to provide an introduction to their study. The names used in this account are necessarily provisional as later critical studies may well lead to corrections or revised opinions.
A Conspicuous Local Feature
Lichens are familiar plants in the Falkland Islands covering the rugged quartzite rocks west of Stanley, for example at Wall Mountain, coating the boulders on stone runs, and making grey, orange and black bands on rocky sea shores. Yet, in spite of being so conspicuous, they have been almost ignored by botanists and naturalists as their component parts (algae and fungi) are microscopic.
Existing Collections
Staff from the British Antarctic Survey have often collected specimens during visits to Stanley between journeys to or from South Georgia or the Antarctic, many of which are housed in the BAS herbarium in Cambridge. Dr Henry A Imshaug led a team who collected over 3,000 specimens in the 1960's, but these have remained relatively neglected in Michigan State University. Dr Alan Fryday has recently been appointed to reappraise these.
International Context and Identification
Many species are virtually universal in their distribution, but others are much more geographically restricted. The Falkland lichen flora is most similar to that of Tierra del Fuego but some species superficially resemble European species, but differ slightly in their chemical constitution. This situation, familiar enough to biogeographers, is particularly taxing in the Falklands because of the lack of published work to help in identification.
Notable and Typical Species
I found some interesting plants such as Verrucaria dermoplaca on shoreline rocks at its typical locality in Fox Bay, West Falkland. Finds of this kind allow us to participate a bit in the activities of botanists and explorers from the past - brought home to me when I came upon the Tide Guage set up by the crews of Erebus and Terror at Port Louis in 1842. On the rock face by this site, there are extensive fruiting thalli of Haematomma erythromma, a species that becomes mainly sterile further south (in fact the majority of the thalli that I saw in the Falklands were vegetative). On these rocky shores (and especially those where more resistant rocks are present the characteristic colour zones so familiar to European botanists are well-developed.
The rocky shore at Saunders Island showing coastal lichen zonation with dark Verrucaria to left,
orange Caloplaca (mostly C. sublobulata) zone in middle, and grey Ochrolechia on higher rocks to right.
(Photo by K Dalby)
Lichen Habitats
It appears that the richest sites include steep sea and river cliffs (inaccessible to grazing animals) and unimproved moorland areas, and the higher ground on the hills, especially where the terrain is rugged or the sites are far removed from roads or settlements. Sea cliffs dominated by tussac grass have little lichen cover, but lichens become conspicuous at some sites.
Land management history must be crucially important in some places (many tussac grass stands have been destroyed by fire). However, at Port Louis eroded over-grazed paddocks still support diminutive thalli of several foliose lichen species. These remain as potential sources for regeneration should grazing pressure be reduced.
Lichens on Shrubs
The lichens of Diddle-dee heathland are superficially very similar to many from comparable habitats in Europe. Thus the yellowish tufts of Coelocaulon will probably be C. Aculeatum, and red-fruited Caldonia are likely to be C. Floerkeana. Old stems of Native Box on the sea cliffs of Saunders Island are pink-orange with a crustose lichen probably allied to Belonia, with spirally arranged fungal hyphae clinging to algal filaments. Though this is very noticeable in the field, the red colour quickly fades with storage (in contrast to the more stable orange of Xanthoria candelaria which is so charactistics of tree and bushes in the settlements).
One very interesting lichen is Thamnolia vermicularis which grows in thick white cushions or tufts of white wormlike stems. This is a very widely distributed species which has never been known to produce apothecia, soredia or isidia, so all dispersal must be vegetative. None of my four gatherings flouresces with UV light, so they must all belong to the subsp. vermicularis, exactly as would be expected from the world distribution of the two sub species (see the map, fig 5, in Sheard, 1977).
Lichens on Rock and Stone
Hard sandstone outcrops support the very attractive black and yellow Usnea (Neuropogon aurantiaco-atra) used locally on a small scale for dyeing. This species is protean in growth form, resulting in numerous synonyms in the literature with at least 6 taxa having been described from the Falkland Islands (Walker 1985). It is best developed on nearly horizontal surfaces where it forms extensive dark turfs. In the great stone runs of East Falkland - Darwin's 'streams of stones' - and on the small equivalents in West Falkland, species of Pertusaria and Ochrolechia cover exposed rock surfaces with rough grey or brownish crustose thalli. These are mostly sterile, and some may be intractable taxonomically.
In Conclusion
Duplicates of my Cladonia samples are with Soil Steenroos, awaiting naming and DNA analysis as part of studies to reveal the scale of genetic divergence between plants of the same species but in different hemispheres.
It may be premature at this stage to suggest which Falkland habitats support the greatest number of lichen species, but this will be essential for maintenance of environmental biodiversity and conservation purposes in the Falklands of these fascinating plants.
Acknowledgements
My visit was supported by funding from the Shackleton Scholarship Fund, augmented by help from the Percy Sladen Memorial Fund in London. Many people helped me during this visit to the Falklands. I wish particularly to thank Brian and Penny Hill for hospitality in Stanley, Peter and Melanie Gilding in Port Louis, the late Robin Lee in Port Howard, and Susan Pole-Evans at Saunders Island. Becky Ingham and her staff at Falklands Conservation and Jim McAdam in Belfast played an invaluable role in helping to plan the visit. Finally, various lichenologist friends have promised assistance with identifications which go beyond my limited knowledge of the southern hemisphere lichen flora.
References
Grass, M M. 1952. Contribusion al catalogo de liquenes Argentinos, 1. Lilloa, 24, 5-294, .
Imshaug H A. 1968. Expedition to the Falkland Islands. Antarctic JI US, 4. 247-248.
Ovstedal D O and Lewis-Smith F I (In press). Lichens of Antarctica and South Georgia.
Sheard J W. 1977. Palaeogeography, Chemistry and Taxonomy of the Lichenlized Ascomycetes Dimelaena and Thamnolia. The Bryolist. 80, 100-118.
Walker F J. 1985. The lichen genus Usnea subgenus Neuropogon. Bull Br Mus Nat Hist (Bot.) 13 (1): I 130.
Tussac Restoration Project
Progress at Port Harriet
by Rebecca Ingham and Mike Evans
Project aims to Protect Remaining Tussac Areas
The depressing decline of tussac grass around the Islands has been regularly featured in the newsletters and journals of the Falklands Islands Foundation and Falklands Conservation over the last 15 years. These reports have noted that large areas of tussac have been lost to grazing and erosion and those areas remaining are fast becoming the Falklands most valuable and endangered natural habitats. In order to protect these remaining areas and to help the people trying to manage them, Falklands Conservation launched the Tussac Appeal in early 2000. Funds raised will pay for fencing and sectioning of remaining tussac grass areas to ensure their future careful management and sustainable use. With support, encouragement and advice from the Department of Agriculture plans are now well advanced to protect an important tussac grass area at Port Harriet. Discussions are well under way for possible sites at Cape Dolphin, to the north west of East Falkland.
The Port Harriot Area showing the Tussac Appeal Fencing (in Red)
Appeal Progress
A tremendous response to this Appeal has come from our members* who have already contributed over f5,000. The Falkland Islands Company has offered to help with the transport of fencing materials. A raffle was held in the Islands to raise funds, with a limited edition of Mandy Shepherd's beautifully illustrated book 'The Falkland Islands' being kindly donated by the author. The Appeal is on-going and will continue to negotiate for practical protection measures to be implemented at additional tussac sites as funds permit.
Port Harriet: Importance and Management
The first site to be tackled is at Port Harriet Point. This is a tussac covered point to the south of Stanley. The land is owned by the Falkland Islands Government, but leased and managed on a long-term basis by tenants Jo Newell and Mike Evans. Jo and Mike have a high interest in sustaining the wildlife value along with the agricultural value of the area which they use primarily for high quality shelter and grazing for horses.
Port Harriet is an important area for several reasons. It is home to a breeding colony of Southern Sea Lion, a colony of up to 70 was recorded during the 1999-2000 season. We will be monitoring their progress with interest over the next few years. In addition, it also has a breeding colony of Magellanic penguins, provides shelter for a wide range of small birds and is an important feeding ground for immature Red-backed Hawks and Turkey vultures.
Port Harriet: Tussac Restoration Plans
Port Harriet is a long thin spit of land, approximately 4km in length. Tussac grass grows along its entire length up to the heavily covered Tussac point with particularly dense areas scattered around the edge of its long coastline. The last kilometre of the peninsula is currently managed as a private Nature Reserve. The main fencing provided by the Tussac Appeal will be used to split the peninsula along it's length, with four smaller fences dividing the area into a total of 11 small areas. In this way, stock can be excluded from certain areas while replanting and re-growth of the Tussac grass takes place.
After the initial fence-building at the end of the austral summer 2000-2001, there will be a period of Tussac planting in some of the divided sub-sections. These re-planting days are to be open to everyone who is interested in lending a hand, so please call the Falklands Conservation office in Stanley for more details if you think you can help. The long-term aim is to increase both the area and the quality of tussac grass at Port Harriet, while still ensuring that the land can be used in a sustainable way. This now looks like becoming a reality, thanks to the co-operation and efforts of everyone who has contributed to the Project.
* We gratefully acknowledge below those who have the generously supported the Tussac Restoration Project Appeal:
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The Falkland Islands Zebra Trout
Aplochiton zebra
by R.M. McDowall, National Institute of Water and Atmospheric Research, Christchurch, New Zealand
Darwin's Discovery
When the H.M.S. Beagle, with Charles Darwin aboard, was anchored in Berkeley Sound, in northeastern East Falkland, in the late 1830s, a fish specimen was collected, preserved, and taken back to Great Britain for description. British biologist Leonard Jenyns called it Aplochiton zebra, the use of 'zebra' being an allusion to bold, dark vertical stripes across the sides of the fish, and the common name 'zebra trout' has achieved wide and general usage around the Islands. Where Darwin's specimen was collected from is unrecorded, apart from the fact that it came from a lake, but quite possibly it was Magellan Pond, near Johnson Harbour in Berkeley Sound, though this is speculative. Darwin and some others from the crew of the Beagle walked south and west as far as Goose Green and would have passed several ponds and lakes on this trip, where zebra trout could also have been collected.
A Once Common Fish in Decline?
Over the years since the fish was collected it has been repeatedly recorded from the Falklands, as well as from Patagonian South America. The fish has been an item of food for Falklanders, no doubt welcomed, and there are stories of fish being caught and cooked on a shovel held over a fire fuelled by diddle-dee - a tasty morsel for a cold, hungry shepherd. Zebra trout were widespread, common, and easy to catch, and even in recent decades there are reliable stories of dozens of fish being caught in a day. However, there have been persistent suggestions that numbers of zebra trout have recently been in serious decline, and that the fish is no longer to be found in some river systems where it was formerly known. Decline in abundance and range of zebra trout has been blamed on the introduction and establishment of European brown trout, Salmo trutta, in Falkland Islands streams, though this connection has never been confirmed (and it would be very difficult to do so in a rigorous way).
A Wide-ranging Survey Undertaken
With these points in mind, in the company of two further New Zealand fish biologists (Richard Allibone and Lindsay Chadderton), I undertook a wide-ranging survey of Falkland Islands streams during November 1999 (with funding support from the National Geographic Society, Washington, the Shackleton Scholarship Fund, and some New Zealand funding sources). During three weeks, using a variety of fishing techniques, including traps, nets and electric fishing equipment, we sampled 146 sites widely across the two main islands (see Fig. 1), working extensively in all the main areas except West Falkland south of Fox Bay. In interpreting our findings it is important to realise that we were there at only one time of the year, that there are lots of streams and ponds that we did not visit, and that we could have missed fish species present in some of the streams and ponds that we did sample. But accepting this caveat, we did collect from a large number of sites the results of which detailed as follows.
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Survey Results
Amongst the 146 sites, there were no fish at 16 sites; of the remaining 130 sites, the native minnow, Galaxias maculatus, was the only species present at 57 sites, the introduced brown trout was the only species at 45 sites, only zebra trout occurred at 3 sites, minnows plus zebra trout were found at 13 sites, minnows and brown trout at 10 sites, and all three species at only 2 sites (and at both of the latter we collected only 1 zebra trout). The general lack of zebra trout at sites where brown trout were found is particularly telling, and consistent with suggestions that the introduction of brown trout has had a damaging effect on zebra trout distribution and abundance.
Zebra trout were found to be reasonably widespread and abundant in two areas: On East Falkland we found them across Lafonia, and this interestingly is an area that the brown trout has scarcely invaded - though a few have been found recently in at least one of the rivers along the northeastern coast of Lafonia;
On West Falkland, zebra trout are widespread in streams and lakes draining into Philomel Harbour in the west, and interestingly, this is an area where brown trout are presently unknown, perhaps because the sea-migratory brown trout present on the Falklands have yet to find their way through the rather narrow entrance to the harbour.
In addition, zebra trout were found to be abundant in Red Pond, a small lake on Port Howard Farm. Red Pond has no outlet, so that the population of zebra trout must be landlocked in the pond (unlike other populations where there is almost certainly a sea-migratory stage in the species' life history). Thus, in Red Pond (as mostly elsewhere), zebra trout were found in a place where brown trout have not yet become established. Although we have not been able to demonstrate any causal connection between the distribution and abundance of zebra trout and the presence of the introduced brown trout, our data are certainly consistent with the quite widely expressed view that brown trout are causing the decline in zebra trout.
What of the future for zebra trout?
There seems no obvious reason why, eventually, brown trout will not spread more widely into unoccupied Lafonia stream systems, and also find their way into Philomel Harbour and the river systems that drain into it. If so, the future for zebra trout looks bleak. This really emphasises the importance of the population in Red Pond, as this is the only known population where trout cannot gain natural access. There may be other undiscovered landlocked populations of zebra trout in lakes, e.g. we were told that they occurred in both Magellan Pond and Lorenzo Pond, but did not find any there. And we netted several of the lakes in the series north of Fox Bay and found only minnows. While landlocked populations like that in Red Pond are certainly better than nothing, they do represent somewhat 'minimalised' stocks of a fish that would normally undertake migrations to and from the sea. Recent moves to introduce regulations that prohibit the capture of zebra trout are certainly commendable, but whether they are enough to ensure the species' survival only time will tell. Loss of this fish from the already very sparse Falkland Islands freshwater fish fauna would be a tragedy.
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