The microarthropods of sub-Antarctic Prince Edward Island: a quantitative assessment

The biodiversity in the sub-Antarctic region is threatened by climatic change and biological invasions, which makes the understanding of distributions of biotas on sub-Antarctic islands essential. Although the distribution patterns of vascular plants and insects on sub-Antarctic islands are well documented, this is not always the case for microarthropods. This study provides the first quantitative assessment of the distribution and abundance of microarthropods on Prince Edward Island (PEI), one of two islands in the Prince Edward Island group. Microarthropod community structure differed significantly between PEI and nearby Marion Island, with only two invasive alien species found on PEI compared with Marion Island. Furthermore, species richness, abundance and community structure differed significantly between habitat types on both islands. This study emphasizes the importance of quarantine measures when visiting PEI to maintain its status as one of the more pristine islands in the sub-Antarctic region.     

Littoral Acari of Marion Island: ecology and extreme wave action

Fourteen species of littoral Acari (Arachnida) were collected from the shores of sub-Antarctic Marion Island, of which Parasitiphis brunneus (Kramer) (Ologamasidae), Rhombognathus apsteini Lohmann and R. gressitti Newell (Halacaridae) are new to the Prince Edward Islands. Acari, impoverished both in terms of diversity and abundance, were confined to the few micro-habitats, including rocky-shore lichens, kelp holdfasts, other macroalgae and the surface pitting of mobile boulders, which provided protection from the direct and indirect stresses of severe wave action.     

The biology of Bothrometopus elongatus (Coleoptera, Curculionidae) in a mid-altitude fellfield on sub-Antarctic Marion Island

Bothrometopus elongatus is one of four Ectemnorhinus-group species restricted to the epilithic biotope on the Prince Edward Islands. Here we examine the biology of this species over a full year at Kerguelen Rise, a mid-altitude fellfield site on Marion Island. B. elongatus adults eclose from April onwards, reaching maximum densities (ca. 17 individuals m⁻²) in September. Females mature approximately three eggs at a time and these commence hatching in July. Larval eclosion reaches a peak in November, during which time larval densities are also highest (ca. 153 individuals m⁻²). The larvae develop through six instars, which is within the range found for other Ectemnorhinus-group species. The high densities of B. elongatus in fellfield habitats, and its single, virtually discrete annual generation, make this species unusual among insects indigenous to the sub-Antarctic. The latter generally have low densities compared to other micro-arthropods, prolonged life-cycles, and flexible life-histories. We suggest that the diversity of life-histories found amongst the indigenous insects at Marion Island presents considerable potential for testing environmental effects on insect life-histories. An overview of sub-Antarctic insect life-history data suggests that the indigenous species, with generally prolonged life-cycles, are at a disadvantage relative to introduced species that have more rapid cycles and often complete several generations per year. This is reason for concern given rapid climate change at these islands. Accepted: 14 November 1999     

Patterns in the benthic communities on the shelf of the sub-Antarctic Prince Edward Islands

Summary Benthic communities at the sub-Antarctic Prince Edward Islands were sampled qualitatively with an epi-benthic sled at 57 stations over a five year period. Additional information on these communities was obtained from replicate underwater photographs. In total, 546 macrofaunal species were found. Despite the extreme isolation and geological youth of the islands, there seems to have been a diverse colonisation. A cluster-analysis based on species abundance aggregated most stations into 8 groups. Each of these groups had a unique depth and substratum combination. Thourella variabilis (Octocoralea), and Cabarea darwinii (Bryozoa) characterised deep rocky assemblages and Serpula vermicularis, Lanice conchilega (Polychaeta) and Magellania kerguelenensis (Brachiopoda) characterised soft substrata. Indicator species separating each of the 8 clusters are given. Trends in percentage cover and densities of major taxa with respect to depth and substratum, as shown by photographs, are described. Deep, rocky substrata were dominated by Porifera, Bryozoa and Cnidaria, while soft-substrata were dominated by Polychaeta, Bivalvia and Brachiopoda. Errant forms consisted predominantly of Echinodermata, with Crustacea being important in shallower habitats. Filter-feeders dominated the benthos of the islands in all habitats.     

Molecular and morphometric assessment of the taxonomic status of Ectemnorhinus weevil species (Coleoptera: Curculionidae, Entiminae) from the sub-Antarctic Prince Edward Islands

There are long‐standing controversies on the taxonomic status of Ectemnorhinus weevil species occurring on the sub‐Antarctic Prince Edward Islands. Since the two islands that constitute the Prince Edward Islands archipelago (PEIA), Marion Island (MI) and Prince Edward Island (PEI), differ in terms of alien invasive species such as the introduced house mouse Mus musculus and conservation management strategies, it is important to consider inter‐island dynamics when investigating inter‐specific relationships. Using a combined molecular phylogenetic and morphometric approach, we attempted to resolve the taxonomic status of the PEIA Ectemnorhinus weevil species. A COI gene phylogeny was inferred following the genetic characterization of 52 Ectemnorhinus weevils from both islands, and morphometric assessment using a set of 15 linear, external measurements was used to differentiate between the two currently recognized species, Ectemnorhinus similis and Ectemnorhinus marioni. Analyses revealed the presence of two genetically and morphometrically distinct species on PEI, whilst evidence for a single species, comprising diverse genetically discrete populations was found on MI. Based on these results, the species unique to PEI has been designated Ectemnorhinus kuscheli n. sp. whilst we confirm the synonymy between E. similis and E. marioni, the two species originally described from MI. E. kuscheli appears to be restricted to PEI, whereas E. similis occurs on both MI and PEI.     

Climate change and the short-term impact of feral house mice at the sub-Antarctic Prince Edward Islands

At the Prince Edward Islands, temperatures have increased by approximately 1°C over the past 40 years, accompanied by a decline in precipitation. This has led to a reduction in the peat moisture content of mires and higher growing season warmth. The temperature-and moisture-sensitive sedge, Uncinia compacta R. Br. (Cyperaceae), has consequently increased its aerial cover on Prince Edward Island, but harvesting of seeds by feral house mice (up to 100% removed) has prevented this from happening on Marion Island. Such extensive use of resources suggests that prey switching may be taking place at Marion Island. Scat analyses revealed that mice are·not only eating ectemnorhinine weevils to a greater extent than found in previous studies of populations at Marion Island, but that they also prefer larger weevils (±6 mm). A decrease in body size of preferred weevil prey species [Bothrometopus randi Jeannel and Ectemnorhinus similis C.O. Waterhouse (Coleoptera: Curculionidae)] has taken place on Marion Island (1986–1992), but not on Prince Edward Island. This appears to be a result of increased predation on weevils. In addition, adults of the prey species, E. similis are relatively more abundant on Prince Edward Island than adults of the smaller congener E. marioni Jeannel, and could not be found on Marion Island in the late austral summer of 1991. These results not only provide support for previous hypotheses of the effect of global warming on mouse-plant-invertebrate interactions on the Prince Edward Islands, but also provide limited evidence for the first recorded case of predator-mediated speciation. They also show that the interaction of human-induced changes operating at different scales may have profound consequences for local systems.     

Burrow densities and nest site preferences of petrels (Procellariidae) at the Prince Edwards Islands

Summary The nest-site preferences of six burrowing petrel species, Salvin's prion Pachyptila vittata salvini, blue petrel Halobaena caerulea, great-winged petrel Pterodroma macroptera, Kerguelen petrel Pterodroma brevirostris, soft-plumaged petrel Pterodroma mollis and white-chinned petrel Procellaria aequinoctialis, in the northeastern part of Marion Island (Prince Edward Island group, southern Indian Ocean) were analyzed by step-wise multiple regression. The nest-site characteristics measured were slope angle, soil depth and moisture content, percentage cover by stones or boulders and percentage cover by each of seven major plant species. The major nest-site preferences were: exposed areas with shallow soil (Salvin's prion); steep coastal slopes (blue petrel); sheltered well-drained slopes with deep soil (great-winged petrels); wet areas along drainage lines (Kerguelen petrel); steep slopes (soft-plumaged petrel); and areas with deep soil (white-chinned petrel). Similar species showed no significant avoidance of nest sites where there were burrows of potential competitors but did tend to nest spread out over different habitats. Burrow densities were determined in six habitat and seven vegetation types. Salvin's prion was the most abundant species (81% of burrows, with a maximum density of 279 burrows ha^-1) and used both burrows and natural cavities for nesting. For all species combined, burrow densities at Marion Island were lower than in comparable habitats and vegetation types at neighbouring Prince Edward Island. Depredation by feral house cats Felis catus, absent from Prince Edward Island, is assumed to be largely responsible for this difference.     

Trophic importance of the chaetognaths Eukrohnia hamata and Sagitta gazellae in the pelagic system of the Prince Edward Islands (Southern Ocean)

Trophodynamics and predation impact of the 2 dominant chaetognaths Eukrohnia hamata and Sagitta gazellae were investigated at 19 stations in the vicinity of the Prince Edward Islands and at a 24-h station occupied at the sub-Antarctic Front in late summer (April/May) 1996. During the entire investigation, the zooplankton assemblages were numerically dominated by copepods with densities ranging from 21 to 170 ind. m⁻³. Amongst the copepods, Clausocalanus brevipes, Metridia gerlachei and M. lucens dominated accounting for >90% of the total. Generally, chaetognaths were identified as the second most important group composing at times up to 30% (mean = 14.7%) of total zooplankton abundance. Of the two chaetognath species, E.␣hamata was generally numerically dominant. Gut content analysis showed that both chaetognath species are opportunistic predators generally feeding on the most abundant prey, copepods. No feeding patterns were evident during the 24-h station, suggesting that both species feed continuously. The feeding rates of E. hamata ranged from 0 to 0.50 prey ind. day⁻¹ and between 0 and 0.90 prey ind. day⁻¹ for S. gazellae. The maximum total predation impact of E. hamata was equivalent to 5.2% of the copepod standing stock or up to 103% of copepod production per day. For S. gazellae the predation impact was lower, reaching a level of 3.2% of the copepod standing stock or 63% of the daily copepod production. Chaetognaths can, therefore, be regarded as an important pelagic predator of the Prince Edward Islands subsystem. Received: 27 March 1997 / Accepted: 11 September 1997     

Habitat use and home range size of red foxes in Prince Edward Island (Canada) based on snow-tracking and radio-telemetry data

There is a lack of information regarding the ecology and behaviour of red foxes that can be used to elaborate effective management programs for this species on Prince Edward Island (Canada). The main goal of this study was to provide baseline information on habitat selection and home range size of red foxes on Prince Edward Island. Data were collected from snow-tracking and radio-telemetry sessions conducted in two study sites (including one site within Prince Edward Island National Park). Our results indicated that red foxes selected for roads and human-use areas during both the breeding and the kit-rearing seasons in the park. Outside the park, however, the data failed to conclusively show that foxes have a unique preference for human-use habitats or roads. Forests were selected against in both study sites. Although roads are frequently visited by foxes during the kit-rearing season in the park, each individual fox typically stays in this habitat only for short periods of time (< 15 min). This finding suggests that foraging efficiency along the roads is very high possibly reflecting the abundance of anthropogenic food sources. Overall, we present the largest amount of data on habitat selection ever collected for red foxes in Prince Edward Island, Canada. Our results show that food sources in human-use areas and roads are altering the selection and/or use of habitats of red foxes in some areas of Prince Edward Island.     

New records of alien vascular plants from Marion and Prince Edward Islands, sub-Antarctic

A survey was made of the distribution of introduced vascular plants on Marion and Prince Edward Islands. The results of this survey were compared to results of previous surveys (1965/66, 1975, 1981, 1989). Four new introductions to Marion Island have taken place, three of which involved species that had been introduced in the past, but had disappeared or were eradicated. Eighteen species of alien vascular plants are now known from Marion Island. Of these, three were not observed during the present survey, and another three have been eradicated. Many of the naturalised aliens are still increasing markedly in area and/or in numbers. Rates of spread of up to 300 m year⁻¹ occur. Three alien vascular species occur on Prince Edward Island. Two are recent introductions, presumably transported to this island from neighbouring Marion Island by wind or birds. Accepted: 22 November 1998     

Freshwater ascomycetes: Jahnula apiospora (Jahnulales, Dothideomycetes), a new species from Prince Edward Island, Canada

A new ascomycete species, Jahnula apiospora (Jahnulales, Dothideomycetes), collected from submerged wood in a freshwater creek on Prince Edward Island, Canada, is described and illustrated. The characteristic features of the new species are globose to subglobose, black, ostiolate, membranous ascomata with broad, brown, subtending hyphae; a peridial wall composed of an outer layer of thick-walled cells occluded by black, amorphous material along the upper two-thirds of the ascoma; trabeculate pseudoparaphyses; cylindrical to narrowly fusoid, fissitunicate asci; and brown, one-septate, apiosporous ascospores without a gelatinous sheath or appendages.     

Structure and distribution of the slope fish community in the vicinity of the sub-Antarctic Prince Edward Archipelago

Demersal fish community structure, distribution and trophic relationships on the slope (depth range 200–1500 m) of the sub-Antarctic Prince Edward Islands and surrounding sea rises were investigated during a pilot survey conducted in April 2001 onboard fishing vessel MV Iris . A total of 56 fish taxa were collected during the survey, of which 44 were identified to the species level, seven to the genus level and five to the family level. Among the identified taxa, 36 constituted new records for the area investigated. Total catch per unit effort (cpue) during the survey ranged from 1·1 to 241·2 individuals h⁻¹. Both average fish diversity and total cpue positively correlated with trawling depth. Overall, mean sampling depth and near-bottom temperature explained 56% of total fish cpue. Hierarchal cluster analysis identified three distinct fish assemblages with pronounced dominant species. Major shifts in fish community composition occurred at 500–600 m and 800–900 m depth strata and could probably be a result of physical and biological vertical zonation. Analysis of the diet of selected fish species showed that they were generalist feeders, consuming predominantly pelagic, including epipelagic, meso- and benthopelagic, prey. Diets of six species and nitrogen stable isotope signatures of 22 species revealed that with a few exceptions most fishes occupied the fourth trophic level and were tertiary consumers. Wide variability in carbon isotopic signatures is discussed with respect to alternative, e.g . possible importance of high Antarctic and chemoautotrophic v . photoautotrophic sub-Antarctic primary production, organic matter sources at the base of deep-sea food webs.     

FORAGING BEHAVIOUR OF NONBREEDING IMPERIAL CORMORANTS AT THE PRINCE EDWARD ISLANDS

Cooper, J. 1985. Foraging behaviour of nonbreeding Imperial Cormorants at the Prince Edward Islands. Ostrich 56: 96–100.

The Imperial Cormorant Phalacrocorax atriceps is an inshore, primarily solitary forager in the nonbreeding season at the Prince Edward Islands. All girds foraged within 400m of the coast, most seaward of a thick Macrocystis kelp bed. Mean dive duration was 40,2s with a maximum of 88s. The ratio of dives to surface rests was 2,68. Birds foraging very close inshore in shallow (<2 m) water dived for shorter periods than those farther offshore in deeper water. The Imperial Cormorant at the Prince Edward Islands appears to be rimarily a bottom-feeder. Foraging bouts were of short duration and little time was spent flying luring foraging. Imperial Cormorants dive for longer periods than do nearly all other species of cormorants.     

Relationship between cover of Chondrus crispus (Gigartinales,Rhodophyta) and Phymatolithon (Corallinales,Rhodophyta) on friable rock substrata

Field observations in sublittoral Prince Edward Island, Canada, indicated that on a friable sandstone substratum Chondrus crispus was more commonly associated with Phymatolithon sp. than with bare rock. Thus, a substantial proportion of the population of Irish moss along the coast of Prince Edward Island occurs on this encrusting coralline. These observation may be explained on the basis of the relative stability of the substratum in contrast to other studies in which sloughing of epithallial cells by species of both Phymatolithon and Lithothamnium has been reported to limit epiphytism by fleshy macrophytes.Issued as NRCC 31426.     

Holothurians (Echinodermata) from Marion and Prince Edward Islands: new and little-known species

Two new species Mesothuria edwardensis sp.n. and Paradota marionensis sp.n., and four little-known species Cucumaria kerguelensis Théel, 1886, Cladodactyla crocea croceoides (Vaney, 1908), Psolidium incertum (Théel, 1886) and Synallactes challengeri (Théel, 1886) of holothurians are described from Marion and Prince Edward Islands.     

Diet and daily ration of two nototheniid fish on the shelf of the sub-Antarctic Prince Edward Islands

The seasonal dietary composition and estimates of daily consumption rate of Lepidonotothen larseni and Gobionotothen marionensis juveniles were obtained for the first time using fish collected near sub-Antarctic Prince Edward Islands during April 1999–2003. The diet of L. larseni consisted mainly of pelagic prey, with copepods and arrow worms making up the most significant prey groups and accounting for 46% and 40% of prey mass, respectively. The diet of G. marionensis was more diverse than that of L. larseni and was composed mainly of benthic prey, including bottom-dwelling decapods (Nauticaris marionis) and sedentary polychaetes, which accounted for 54% and 30% of prey mass, respectively. During the present study, dietary overlap between juveniles of L. larseni and G. marionensis was very low (<5%) indicating that competition for food resources between them was negligible. They not only relied on different prey species, both also exhibited different diel feeding regimes. Daily consumption rate of L. larseni and G. marionensis juveniles was estimated to be 4.5% and 5.2% of body dry mass, respectively. Stomach contents and stable isotope analyses suggested, that both L. larseni and G. marionensis occupy the forth-trophic level of the sub-Antarctic food web but depend mainly on allochthonous and autochthonous (kelp derived) organic matter, respectively.     

The fern genus Elaphoglossum section Lepidoglossa (Dryopteridaceae) in Africa,Macaronesia, the mid‐Atlantic and southern Indian Ocean Islands

Elaphoglossum section Lepidoglossa in Africa, Macaronesia (Azores and Madeira), the mid‐Atlantic Ocean Islands (St Helena, Gough and Tristan da Cunha Island groups) and the southern Indian Ocean Islands (Marion and Prince Edward Islands) is reviewed. Fifteen Elaphoglossum species from this region are ascribed to the section. A new species, Elaphoglossum rivularum , confined to the Chimanimani Mountains in eastern Zimbabwe and formerly ascribed to E. kuhnii from West Africa, is described. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 20–63.     

Molecular diversity of methanogens in feedlot cattle from Ontario and Prince Edward Island, Canada

The molecular diversity of rumen methanogens in feedlot cattle and the composition of the methanogen populations in these animals from two geographic locations were investigated using 16S rRNA gene libraries prepared from pooled PCR products from 10 animals in Ontario (127 clones) and 10 animals from Prince Edward Island (114 clones). A total of 241 clones were examined, with Methanobrevibacter ruminantium accounting for more than one-third (85 clones) of the clones identified. From these 241 clones, 23 different 16S rRNA phylotypes were identified. Feedlot cattle from Ontario, which were fed a corn-based diet, revealed 11 phylotypes (38 clones) not found in feedlot cattle from Prince Edward Island, whereas the Prince Edward Island cattle, which were fed potato by-products as a finishing diet, had 7 phylotypes (42 clones) not found in cattle from Ontario. Five sequences, representing the remaining 161 clones (67% of the clones), were common in both herds. Of the 23 different sequences, 10 sequences (136 clones) were 89.8 to 100% similar to those from cultivated methanogens belonging to the orders Methanobacteriales, Methanomicrobiales, and Methanosarcinales, and the remaining 13 sequences (105 clones) were 74.1 to 75.8% similar to those from Thermoplasma volcanium and Thermoplasma acidophilum. Overall, nine possible new species were identified from the two clone libraries, including two new species belonging to the order Methanobacteriales and a new genus/species within the order Methanosarcinales. From the present survey, it is difficult to conclude whether the geographical isolation between these two herds or differences between the two finishing diets directly influenced community structure in the rumen. Further studies are warranted to properly assess the differences between these two finishing diets.     

Molecular Diversity of Methanogens in Feedlot Cattle from Ontario and Prince Edward Island, Canada

The molecular diversity of rumen methanogens in feedlot cattle and the composition of the methanogen populations in these animals from two geographic locations were investigated using 16S rRNA gene libraries prepared from pooled PCR products from 10 animals in Ontario (127 clones) and 10 animals from Prince Edward Island (114 clones). A total of 241 clones were examined, with Methanobrevibacter ruminantium accounting for more than one-third (85 clones) of the clones identified. From these 241 clones, 23 different 16S rRNA phylotypes were identified. Feedlot cattle from Ontario, which were fed a corn-based diet, revealed 11 phylotypes (38 clones) not found in feedlot cattle from Prince Edward Island, whereas the Prince Edward Island cattle, which were fed potato by-products as a finishing diet, had 7 phylotypes (42 clones) not found in cattle from Ontario. Five sequences, representing the remaining 161 clones (67% of the clones), were common in both herds. Of the 23 different sequences, 10 sequences (136 clones) were 89.8 to 100% similar to those from cultivated methanogens belonging to the orders Methanobacteriales, Methanomicrobiales, and Methanosarcinales, and the remaining 13 sequences (105 clones) were 74.1 to 75.8% similar to those from Thermoplasma volcanium and Thermoplasma acidophilum. Overall, nine possible new species were identified from the two clone libraries, including two new species belonging to the order Methanobacteriales and a new genus/species within the order Methanosarcinales. From the present survey, it is difficult to conclude whether the geographical isolation between these two herds or differences between the two finishing diets directly influenced community structure in the rumen. Further studies are warranted to properly assess the differences between these two finishing diets.     

Mercury concentrations in the Patagonian toothfish, <Emphasis Type="Italic">Dissostichus eleginoides</Emphasis> Smitt 1898, among three distinct stocks

Patagonian toothfish, Dissostichus eleginoides, collections (n = 186) from three distinct stocks (two subantarctic stocks and the stock within the Chilean ZEE) were analyzed for Hg concentration by DMA and comparisons were made by gender, total length (TL), wet weight (WW), and population. There was no difference between TL–WW relationships or Hg concentration by gender within any population across the range examined. The Chilean and Prince Edward Island fish had higher TL-adjusted total Hg concentration than those from the South Georgia and may suggest a possible human health risk. Explanation of these population differences in total Hg may be the actual sample areas and associated hydrogeographic and oceanographic conditions. For example, sampling sites for the Chilean fish lie well outside the Antarctic Convergence whereas the Prince Edward sites straddle the Convergence. The samples obtained from South Georgia lie well within the Antarctic convergence, suggesting that the Polar Front may provide some type of hydrographic barrier as has been shown for this species in terms of larval dispersal and feeding.