Island Of Surtsey Research Articles

A model for wave abrasion on underwater bedrock, with an application to rapidly downwearing tephra cones adjacent to Surtsey Island in Iceland

AbstractWave abrasion is a major erosional process shaping shallow‐water coastal bedrock morphologies. In spite of various erosion studies having been conducted on underwater bedrock features, modelling research for wave‐induced abrasion is limited. Based on an existing formula for bedrock abrasion by fluid flows, this study obtains a predictive equation for the rate of wave abrasion, which is given by a function of a shear stress of wave‐induced, oscillatory bottom flow and the resistivity of bedrock. A model is derived from this equation to describe temporal change in abrasion depth of subaqueous bedrock. The model is applied to rapidly abrading summits of two submarine tephra cones, Jólnir and Syrtlingur, both residing adjacent to the Surtsey volcanic island in Iceland. Nearly horizontal platforms develop as a result of abrasion. Jólnir is a site exposed to storm‐wave attack, while Syrtlingur is a sheltered site. The modelling based on design storm waves is found to well describe temporal change in erosion depth in the middle to late stage of the platform evolution at the two sites. The result of model calculations indicates that: (1) deep‐water wave energy of waves causing abrasion at Syrtlingur is 33% that of waves responsible for abrasion at Jólnir; (2) the efficacy of abrasion occurring at Syrtlingur is about four times higher than that at Jólnir; and (3) the wave base (i.e. the maximum water depth for bedrock erosion) is 51.5 m for Jólnir and 34.4 m for Syrtlingur.

Vascular plant colonisation of Surtsey Island (1965-1990) - a dataset.

BackgroundThe process of ecosystem development over time that takes place on a new substrate devoid of biological activity (such as, for example, lava) is called primary succession. Research on primary succession is not easy, as it is limited to rare occasions when a piece of land totally lacking in any pre-existing life occurs. The emergence of volcanic islands is such an occasion; it is a unique event that allows a natural experiment in the study of colonisation processes and primary succession. Surtsey (located in the Vestmannaeyar archipelago off the southern coast of Iceland) is an iconic example of a place where primary succession has been studied for decades and where human disturbance has been minimised due to significant geographic isolation and early protection efforts. Here, we present a georeferenced dataset of vacular plant occurrences collected during the field studies carried out on Surtsey Island during the first three decades of its existence.New informationTo date, no dataset containing plant distribution data documenting the process of early stages of colonisation of Surtsey has been published. What is more, to our knowledge, there is no other dataset that can be compared with our Surtsey data that is readily available for researchers working on plant colonisation dynamics and primary succession processes. Here, we present a complete, geo-referenced dataset of all plant occurrences (10,094 in total) collected on Surtsey between 1965 and 1990.

Erosion and sedimentation in Surtsey island quantified from new DEMs

We present data from a photogrammetric study on Surtsey island that generated three new DEMs and orthoimages, two from scanned aerial images from 1967 and 1974 and one from high-resolution closerange images from a survey in 2019. DEM differencing allowed for quantification of the erosion and the sedimentation in the island since 1967. Of the subaerial volcanics, about 45% of the lava fields have eroded away but only about 16% of the tuff cones. The prevailing SW coastal wave erosion is evident from the erosive pattern in Surtsey, and the cumulative loss of the coastal margins amounts to 28±0.9x106 m3 since 1967, with the current average erosion rate of 0.4±0.02x106 m3 /yr. Wind deflation and runoff erode the tuff cones and the sediments at the flanks of the cones, with the total volume loss amounting to 1.6±0.2x106 m3 and the current erosion rate of 0.03±0.004x106 m3 /yr. A rapid decline in erosion rates characterized the first years post-eruption, and the coastal erosion rate during the winter of 1967–68 was about 5–6 times higher than the current erosion rate due to the thinner and less cohesive nature of the lava apron at the edge of the shelf. The cones eroded at a rate about 2–3 times higher during the first years due to the uncompacted and unconsolidated nature of the cones at that time. The 2019 area of 1.2 km2 and an extrapolation of the current erosion rate fits well with the projected erosion curve of Jakobsson et al. (2000) with the island becoming a tuff crag after approximately 100 years.

Estimation of phylogenetic divergence times in Panagrolaimidae and other nematodes using relaxed molecular clocks calibrated with insect and crustacean fossils

This study presents the use of relaxed molecular clock methods to infer the dates of divergence betweenPanagrolaimusspecies. Autocorrelated relaxed tree methods, combined with well characterised fossil calibration dates, yield estimates of nematode divergence dates in accordance with the palaeontological age of fossil ascarid eggs and with the previously estimated date of 18 Ma (range 11.6 to 29.9 Ma) for the divergence of theCaenorhabditislineage. Our data indicate thatPanagrolaimus davidifrom Antarctica separatedca21.98 Ma from its currently known, most closely related strain. Thus,P. davidimay have existed in Antarctica prior to the Last Glacial Maximum, although this seems unlikely as it shares physiological and life history traits with closely related nematodes from temperate climates. These traits may have facilitated colonisation of Antarctica byP. davidiafter the quaternary glaciation, analogous to the colonisation of Surtsey Island, Iceland, byP. superbusafter its volcanic formation. This study demonstrates that autocorrelated relaxed tree methods combined with well characterised fossil calibration dates may be used as a method to estimate the divergence dates within nematodes in order to gain insight into their evolutionary history.

The Surtsey Magma Series.

The volcanic island of Surtsey (Vestmannaeyjar, Iceland) is the product of a 3.5-year-long eruption that began in November 1963. Observations of magma-water interaction during pyroclastic episodes made Surtsey the type example of shallow-to-emergent phreatomagmatic eruptions. Here, in part to mark the 50th anniversary of this canonical eruption, we present previously unpublished major-element whole-rock compositions, and new major and trace-element compositions of sideromelane glasses in tephra collected by observers and retrieved from the 1979 drill core. Compositions became progressively more primitive as the eruption progressed, with abrupt changes corresponding to shifts between the eruption’s four edifices. Trace-element ratios indicate that the chemical variation is best explained by mixing of different proportions of depleted ridge-like basalt, with ponded, enriched alkalic basalt similar to that of Iceland’s Eastern Volcanic Zone; however, the systematic offset of Surtsey compositions to lower Nb/Zr than other Vestmannaeyjar lavas indicates that these mixing end members are as-yet poorly contained by compositions in the literature. As the southwestern-most volcano in the Vestmannaeyjar, the geochemistry of the Surtsey Magma Series exemplifies processes occurring within ephemeral magma bodies on the extreme leading edge of a propagating off-axis rift in the vicinity of the Iceland plume.

Birth of two volcanic islands in the southern Red Sea.

Submarine eruptions that lead to the formation of new volcanic islands are rare and far from being fully understood; only a few such eruptions have been witnessed since Surtsey Island emerged to the south of Iceland in the 1960s. Here we report on two new volcanic islands that were formed in the Zubair archipelago of the southern Red Sea in 2011–2013. Using high-resolution optical satellite images, we find that the new islands grew rapidly during their initial eruptive phases and that coastal erosion significantly modified their shapes within months. Satellite radar data indicate that two north–south-oriented dykes, much longer than the small islands might suggest, fed the eruptions. These events occurred contemporaneously with several local earthquake swarms of the type that typically accompany magma intrusions. Earthquake activity has been affecting the southern Red Sea for decades, suggesting the presence of a magmatically active zone that has previously escaped notice.

Anhydrobiosis and freezing-tolerance: adaptations that facilitate the establishment of Panagrolaimus nematodes in polar habitats.

Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. Panagrolaimus davidi, a bacterial feeding anhydrobiotic nematode isolated from Ross Island Antarctica, can survive intracellular ice formation when fully hydrated. A capacity to survive freezing while fully hydrated has also been observed in some other Antarctic nematodes. We experimentally determined the anhydrobiotic and freezing-tolerance phenotypes of 24 Panagrolaimus strains from tropical, temperate, continental and polar habitats and we analysed their phylogenetic relationships. We found that several other Panagrolaimus isolates can also survive freezing when fully hydrated and that tissue extracts from these freezing-tolerant nematodes can inhibit the growth of ice crystals. We show that P. davidi belongs to a clade of anhydrobiotic and freezing-tolerant panagrolaimids containing strains from temperate and continental regions and that P. superbus, an early colonizer at Surtsey island, Iceland after its volcanic formation, is closely related to a species from Pennsylvania, USA. Ancestral state reconstructions show that anhydrobiosis evolved deep in the phylogeny of Panagrolaimus. The early-diverging Panagrolaimus lineages are strongly anhydrobiotic but weakly freezing-tolerant, suggesting that freezing tolerance is most likely a derived trait. The common ancestors of the davidi and the superbus clades were anhydrobiotic and also possessed robust freezing tolerance, along with a capacity to inhibit the growth and recrystallization of ice crystals. Unlike other endemic Antarctic nematodes, the life history traits of P. davidi do not show evidence of an evolved response to polar conditions. Thus we suggest that the colonization of Antarctica by P. davidi and of Surtsey by P. superbus may be examples of recent “ecological fitting” of freezing-tolerant anhydrobiotic propagules to the respective abiotic conditions in Ross Island and Surtsey.

Observations on seals on the island of Surtsey in the period 1980-2012

Grey seals (Halichoerus grypus Fabricius) and harbour seals (Phoca vitulina L.) have been surveyed on the coasts of Iceland since 1980. During the period 1980-2012, both seal species have declined markedly in numbers at the Icelandic coast. The grey seal has established a considerable breeding site on the northern spit of the Surtsey island. This is at present one of the biggest grey seal rookeries on the southern shores of Iceland, with estimated about 60 pups born there in the autumn of 2012. On the other hand, the harbour seal has not been numerous on Surtsey during breeding time in the summer. Breeding sites of harbour seals on the south coast of Iceland closest to Surtsey are in the estuaries of the glacial rivers Ölfusá, Þjórsá, Markarfljót and Kúðafljót. Harbour seals, however, haul-out in great numbers on the northern shores of Surtsey during the winter, presumably using the island as a resting place after foraging in the adjacent waters.

ISSR analysis of two founding plant species on the volcanic island Surtsey, Iceland: grass versus shrub

Prior to the present study there was limited knowledge about the genetic basis of plant colonization on the 50-year-old island of Surtsey, South Iceland. The aim here was to compare genetic structure of two contrasting species, Festuca rubra (arctic fescue) and Empetrum nigrum (crowberry), which have colonized Surtsey since 1973 and 1993, respectively. Inter-simple sequence repeat (ISSR) markers were used to assess genetic diversity and population structure. Two census periods were compared: 1996-1997 and 2005-2006. Using six ISSR primers, we obtained 103 and 139 discernible DNA fragments from F. rubra and E. nigrum respectively. Although the two species displayed similarly high genetic diversity indices (h = 0.238 and 0.235; I = 0.384 and 0.380, respectively), they differed significantly in their genetic profiles. Festuca was genetically structured at the subpopulation level (FST = 0.034, p = 0.007), whereas Empetrum showed a lack of genetic differentiation. A Bayesian STRUCTURE computation further revealed temporal and spatial genetic structure of the species. The early arrival grass F. rubra has expanded from a local genepool. The population was however initially established from different sources, forming a genetic melting pot on Surtsey. On the other hand, the late arrival shrub E. nigrum probably derived from a common source of immigrants.

Ecosystem CO2 flux rates in relation to vegetation type and age of Leymus arenarius dunes on Surtsey

The primary succession on the 50 year old volcanic island of Surtsey, Iceland, has been intensively studied. Initial soil development and other belowground processes are important drivers of primary succession but frequently overseen. A Leymus arenarius and Honckenya peploides dominated plant community has formed a relatively stable successional sere on the island, where external inputs of nutrients remain low. These plants have had a stable <10% aboveground surface cover during the past 20 years, but less is known about their belowground development. We investigated the organic matter (carbon) output and input processes (soil respiration, ecosystem respiration and photosynthesis) of the community and how they were affected by soil temperature, soil water content, vegetation and age of L. arenarius dunes. We found that both soil respiration and root stocks have increased substantially from 1987, when an earlier study was conducted. The same pattern was found when different aged L. arenarius dunes were studied. L. arenarius had a stronger effect on the soil respiration fluxes than its surface cover might indicate, through its much higher photosynthesis rates than H. peploides. The study furthermore illustrated how water stress may temporally limit belowground processes in this coastal community.

Colonization of an empty island: how does a plant with a plastic gender system respond?

Abstract. Honckenya peploides is the most common plant species on the island of Surtsey. It arrived in 1967 and after a juvenile period of 4 years it produced seeds and had increased its number from below 100 to several millions. Most populations had the individuals distributed in a regular or random pattern, suggesting that intraspecific competition is important. H. peploides has a subdioecious reproductive system consisting of pistillate plants producing capsules, and staminate plants delivering pollen. Some of the latter are in addition producing capsules and are denoted hermaphrodites. Populations at the south coast of Iceland had around equal numbers of pistillate and staminate plants. At Surtsey we found more pistillate plants, probably due to their higher water stress tolerance. We also found a tendency to a higher frequency of hermaphrodite plants with a higher number of seeds per capsule compared to populations at the south coast of Iceland and the nearby island of Heimaey. We suggest that this arises from the time right after the colonization of Surtsey where population size was small and the small generalist pollinators were not able to deposit sufficient pollen on pistillate plants, causing the hermaphrodites to have an advantage by being able to set seed after selfing. The result of this initial advantage of the hermaphrodites in combination with the inheritance of the sexes can still be seen due to the longevity of individuals. A generalized account of the colonization history of H. peploides is given.

Spatial genetic structure of the sea sandwort (<i>Honckenya peploides</i>) on Surtsey: an immigrant's journey

Abstract. Sea sandwort (Honckenya peploides) was one of the first plants to successfully colonize and reproduce on the volcanic island Surtsey, formed in 1963 off the southern coast of Iceland. Using amplified fragment length polymorphic (AFLP) markers, we examined levels of genetic variation and differentiation among populations of H. peploides on Surtsey in relation to populations on the nearby island Heimaey and from the southern coast of Iceland. Selected populations from Denmark and Greenland were used for comparison. In addition, we tested whether the effects of isolation by distance could be seen in the Surtsey populations. Using two primer combinations, we obtained 173 AFLP markers from a total of 347 plant samples. The resulting binary matrix was then analysed statistically. The main results include the following: (i) Surtsey had the highest proportion of polymorphic markers as well as a comparatively high genetic diversity (55.5% proportion of polymorphic loci, PLP; 0.1974 HE) and Denmark the lowest (31.8% PLP; 0.132 HE), indicating rapid expansion during an early stage of population establishment on Surtsey and/or multiple origins of immigrants; (ii) the total genetic differentiation (FST) among Surtsey (0.0714) and Heimaey (0.055) populations was less than half of that found among the mainland populations in Iceland (0.1747), indicating substantial gene flow on the islands; (iii) most of the genetic variation (79%, p < 0.001) was found within localities, possibly due to the outcrossing and subdioecious nature of the species; (iv) a significant genetic distance was found within Surtsey, among sites, and this appeared to correlate with the age of plant colonization; and (v) the genetic structure analysis indicated multiple colonization episodes on Surtsey, whereby H. peploides most likely immigrated from the nearby island of Heimaey and directly from the southern coast of Iceland.

Accumulation of nitrogen and organic matter during primary succession of <i>Leymus arenarius</i> dunes on the volcanic island Surtsey, Iceland

Abstract. Initial soil development and enhanced nutrient retention are often important underlying environmental factors during primary succession. We quantified the accumulation rates of nitrogen (N) and soil organic matter (SOM) in a 37-year-long chronosequence of Leymus arenarius dunes on the pristine volcanic island Surtsey in order to illuminate the spatiotemporal patterns in their build-up. The Leymus dune area, volume and height grew exponentially over time. Aboveground plant biomass, cover or number of shoots per unit area did not change significantly with time, but root biomass accumulated with time, giving a root / shoot ratio of 19. The dunes accumulated on average 6.6 kg N ha−1 year−1, which was 3.5 times more than is received annually by atmospheric deposition. The extensive root system of Leymus seems to effectively retain and accumulate a large part of the annual N deposition, not only deposition directly on the dunes but also from the adjacent unvegetated areas. SOM per unit area increased exponentially with dune age, but the accumulation of roots, aboveground biomass and SOM was more strongly linked to soil N than time: a 1 g m−2 increase in soil N led on average to a 6 kg C m−2 increase in biomass and SOM. The Leymus dunes, where most of the N has been accumulated, will therefore probably act as hot spots for further primary succession of flora and fauna on the tephra sands of Surtsey.

Plant colonization, succession and ecosystem development on Surtsey with reference to neighbouring islands

Abstract. Plant colonization and succession on the volcanic island of Surtsey, formed in 1963, have been closely followed. In 2013, a total of 69 vascular plant species had been discovered on the island; of these, 59 were present and 39 had established viable populations. Surtsey had more than twice the species of any of the comparable neighbouring islands, and all of their common species had established on Surtsey. The first colonizers were dispersed by sea, but, after 1985, bird dispersal became the principal pathway with the formation of a seagull colony on the island and consequent site amelioration. This allowed wind-dispersed species to establish after 1990. Since 2007, there has been a net loss of species on the island. A study of plant succession, soil formation and invertebrate communities in permanent plots on Surtsey and on two older neighbouring islands (plants and soil) has revealed that seabirds, through their transfer of nutrients from sea to land, are major drivers of development of these ecosystems. In the area impacted by seagulls, dense grassland swards have developed and plant cover, species richness, diversity, plant biomass and soil carbon become significantly higher than in low-impact areas, which remained relatively barren. A similar difference was found for the invertebrate fauna. After 2000, the vegetation of the oldest part of the seagull colony became increasingly dominated by long-lived, rhizomatous grasses (Festuca, Poa, Leymus) with a decline in species richness and diversity. Old grasslands of the neighbouring islands Elliđaey (puffin colony, high nutrient input) and Heimaey (no seabirds, low nutrient input) contrasted sharply. The puffin grassland of Elliđaey was very dense and species-poor. It was dominated by Festuca and Poa, and very similar to the seagull grassland developing on Surtsey. The Heimaey grassland was significantly higher in species richness and diversity, and had a more even cover of dominants (Festuca/Agrostis/Ranunculus). We forecast that, with continued erosion of Surtsey, loss of habitats and increasing impact from seabirds a lush, species-poor grassland will develop and persist, as on the old neighbouring islands.

Bryophyte colonization history of the virgin volcanic island Surtsey, Iceland

Abstract. The island Surtsey was formed in a volcanic eruption south of Iceland in 1963–1967 and has since then been protected and monitored by scientists. The first two moss species were found on Surtsey as early as 1967 and several new bryophyte species were discovered every year until 1973 when regular sampling ended. Systematic bryophyte inventories in a grid of 100 m × 100 m quadrats were made in 1971 and 1972: the number of observed species doubled, with 36 species found in 1971 and 72 species in 1972. Here we report results from an inventory in 2008, when every other of the grid's quadrats were searched for bryophytes. Despite lower sampling intensity than in 1972, distributional expansion and contraction of earlier colonists was revealed as well as the presence of new colonists. A total of 38 species were discovered, 15 of those were not encountered in 1972 and eight had never been reported from Surtsey before (Bryum elegans, Ceratodon heterophyllus, Didymodon rigidulus, Eurhynchium praelongum, Schistidium confertum, S. papillosum, Tortula hoppeana and T. muralis). Habitat loss due to erosion and reduced thermal activity in combination with successional vegetation changes are likely to have played a significant role in the decline of some bryophyte species which were abundant in 1972 (Leptobryum pyriforme, Schistidium apocarpum coll., Funaria hygrometrica, Philonotis spp., Pohlia spp, Schistidium strictum, Sanionia uncinata) while others have continued to thrive and expand (e.g. Schistidium maritimum, Racomitrium lanuginosum, R. ericoides, R. fasciculare and Bryum argenteum). Some species (especially Bryum spp.) benefit from the formation of new habitats, such as grassland within a gull colony, which was established in 1984. Several newcomers are rarely producing sporophytes on Iceland and are unlikely to have been dispersed by airborne spores. They are more likely to have been introduced to Surtsey by seagulls in the form of vegetative fragments or dispersal agents (Bryum elegans, Didymodon rigidulus, Eurhynchium praelongum, Ceratodon heterophyllus and Ulota phyllantha). The establishment of the gull colony also means that leakage of nutrients from the nesting area is, at least locally, downplaying the relative importance of nitrogen fixation by cyanobacteria growing in bryophyte shoots.

The Nearshore Benthic Community of Kasatochi Island, One Year after the 2008 Volcanic Eruption

A description is presented of the nearshore benthic community of Kasatochi Island 10–12 months after a catastrophic volcanic eruption in 2008. The eruption extended the coastline of the island approximately 400 m offshore, mainly along the south, southeast, and southwest shores, to roughly the 20 m isobath. Existing canopy kelp of Eualaria (Alaria) fistulosa, as well as limited understory algal species and associated fauna (e.g., urchin barrens) on the hard substratum were apparently buried following the eruption. Samples and observations revealed the substrate around the island in 2009 was comprised almost entirely of medium and coarse sands with a depauperate benthic community, dominated by opportunistic pontogeneiid amphipods. Comparisons of habitat and biological communities with other nearby Aleutian Islands, as well as with the Icelandic volcanic island of Surtsey, confirm dramatic reductions in flora and fauna consistent with an early stage of recovery from a large-scale disturbance event.

Succession and benthic community development in the sublittoral zone at the recent volcanic island, Surtsey, southern Iceland

The island Surtsey was formed south of Iceland during an eruption that lasted form 1963 to 1967. The settlement of marine benthic organisms has been monitored at the island from the beginning. First with visits every year but after 1971 with some years between each visit. Since 1984 standard photographs have been shot of the hard substrate in the sublittoral to monitor species composition, cover and density. Data collected 1997 are presented here. In the shallower part of the sublittoral, algae are dominant. Below 15 m depth the cover and density of animals increases and at 30 m algae have disapeared. at the eastern coast the substrate seems more stable than elsewhere along the coast. Multivariate analysis shows two separate communities. a community with a mixture of Mytilus edulis, hydrozoans, Alaria esculenta and Polysiphonia stricta, primarily found where the substrate is unstable, and a community with Laminaria hyperborea, deep water red algae, sponges and Alcyonium digitatum on the more stable substrate.

Formation of a bird community on a new island, Surtsey, Iceland

The present paper summarizes bird observations from Surtsey, iceland since the formation of the island in 1963 until 2008. Continuous observations were maintained in the early years of the island; in spring and autumn 1967–1971 and summers 1970–1973. Since then much of the bird observations are incidental by various scientists and bird watchers visiting the island for a limited period. Different aspects of the bird fauna are examined, the at-sea bird community, vagrants, migrant species, and winter birds, while emphasis is placed on the formation of the breeding bird community. With increasing numbers of breeding species and size of breeding populations as the years passed more structured census of the breeders was needed. Hence whole island censuses were organized in 1990 and 2003. Ringing has been carried out on five occasions. in total 91 bird species have been recorded on or offshore from the island. The first birds started breeding in 1970, Black Guillemot Cepphus grylle and Fulmar Fulmarus glacialis. A total of fourteen species have since bred on the island. Four species of large gulls breed (mostly in one colony); Great Black-backed Gull Larus marinus (bred first in 1974), Herring Gull Larus argentatus (1981), Lesser Black-backed Gull Larus fuscus (~1985), and Glaucous Gull Larus hyperboreus (1993). The colony, starting to form in 1984, has been particularly important for furthering the development of plant and invertebrate communities. Through the fertilizing agency complete vegetation cover is now found in the oldest part of the gull colony. This development has paved the way for terrestrial birds to start breeding; Snow Bunting Plectrophenax nivalis (1996), Greylag Goose Anser anser (~2001) and Meadow Pipit Anthus pratensis (~2003). other breeding species are kittiwake Rissa tridactyla (1975) and White Wagtail Motacilla alba (~2003), but Arctic Tern Sterna paradisaea (1975) has not bred since 1978. in 1990 the island had 316 breeding pairs of six species. in 2003 eleven species bred on the island with a total of about 850 breeding pairs. After 2003 two more species have started breeding, Common Puffin Fratercula arctica (2004) and Raven Corvus corax (2008). Surtsey island was entered on the UNESCo World Heritage list in 2008, not the least for the long history of research and monitoring of various aspects of the island’s natural history. As the breeding bird fauna develops a structured bird monitoring program becomes the more important. Recommendations on how this should be carried out are presented in the paper.

Island Colonization: The Origin and Development of Island Communities

The theory of island biogeography revolutionized the study of island colonization and extinction. Since its inception in the 1960?s, it has allowed scientists and historians alike to understand reasons for patterns of species distributions on islands, as well as assisting conservation managers to model extinction risk of species populations on isolated islands. Volcanic islands represent a ?tabula rasa?, or clean slate for the study of island biogeography, as invariably, resultant volcanic activity decimates almost all observable life. As such, they form the ideal study unit for examining colonization of islands. The Krakatua eruption of 1883 is such an example, with the resultant blasts scouring the Krakatua islands of almost all life, thus allowing scientists to track the colonisation and successional stages that followed. Another example is Surtsey Island, which emerged from the sea 40 km south of Iceland in 1963. It represented a unique opportunity to examine colonization of a previously non-existent and thus uninhabited island. Given that there are many influences and avenues governing the origin and colonization of life on islands, Island Colonization: The Origin and Development of Island Communities, edited by Tim New, represents an important book compiling information on this topic.

Colonization of lichens on Surtsey 1970–2006

A list of lichen species from the volcanic island Surtsey is presented. A total of 87 species have been recorded since the first three species appeared in 1970. Notes on distribution and short description of the main lichen communities are given. Possible colonization routes to the island are discussed. Four of the species treated are new to iceland, Gyalidea fritzei and Psilolechia clavulifera and two species, one Lecanora and one Stereocaulon which probably are new to science. Two further species belonging to Lecanora, provisionally determined as L. albescens and L. semipallida, are probably new to iceland. The primary colonization resembles what has been recorded on other lava fields in iceland. Lichen species established very slowly on Surtsey with relatively few species found during the first two decades, in 1984 only 17 species had been recorded. That number almost doubled during the next six years, 31 species had been recorded on the island by 1990 and there has been a constant accumulation of species since then. The lichen colonization benefitted from the activity of gulls. Many species were probably dispersed by the trampling birds and colonized the naked lava rock around the breeding area. Later soil formation started in connection with the gull colony and the first colonizers were replaced by other species. The palagonite tuff has only recently been colonized by lichens and on the coastal rocks of the island only one lichenized species has been found so far.