scholarly journals Marine hotspots of activity inform protection of a threatened community of pelagic species in a large oceanic jurisdiction in the South Atlantic

2019 ◽  
Author(s):  
Susana Requena-Moreno ◽  
Steffen Oppel ◽  
Alex Bond ◽  
Jonathan Hall ◽  
Jaimie Cleeland ◽  
...  
Keyword(s):  
Management Strategies ◽  
Oceanic Islands ◽  
South Atlantic ◽  
The South ◽  
Animal Tracking ◽  
Marine Management ◽  
Tristan Da Cunha ◽  
Fur Seals ◽  
Four Seasons ◽  
Marine Areas

Remote oceanic islands harbour unique biodiversity, especially of species that rely on pelagic resources around their breeding islands. Identifying marine areas used by such species is important to reduce or limit threats that may put these species at risk. The Tristan da Cunha group of islands in the South Atlantic Ocean hosts several endemic and globally threatened seabirds and pinnipeds; how they use the waters surrounding the islands must be considered when planning industrial activities in the entire Exclusive Economic Zone (EEZ). We identified hotspots of activity by collating animal tracking data from nine breeding seabirds and one marine mammal to inform marine management in the Tristan da Cunha EEZ.To detect statistically significant areas of concentrated activity, we calculated the time-spent-in-area that tracked individuals (breeding adults) of 10 focal species (mainly breeding adults of nine seabirds and adult female Subantarctic fur seals Arctocephalus tropicalis) invested in a grid of regular 10 × 10 km cells within the EEZ, for each of four seasons to account for temporal variability in space use. Applying a spatial aggregation statistic over these grids by each species we detected areas that are used more than expected by chance. Most of the activity hotspots were either within 100 km of the islands or were associated with seamounts being spatially constant across several seasons. Moreover, some species spend a large proportion of their time-at-sea inside the EEZ during certain breeding stages, rendering the sites we identified critical for their fitness. Our approach provides a simple and effective tool to highlight important areas for pelagic biodiversity that will benefit Tristan da Cunha’s conservation planning and marine management strategies.

scholarly journals Fur Seals Return to Gough Island

Oryx ◽  
1981 ◽  
Vol 16 (1) ◽  
pp. 46-47 ◽  
Author(s):  
W.R.P. Bourne
Keyword(s):  
South Atlantic ◽  
The South ◽  
Tristan Da Cunha ◽  
Fur Seals ◽  
Gough Island

After a somewhat perilous landing on Gough Island, south of Tristan da Cunha in the South Atlantic, the author was able to confirm the remarkable comeback of the fur seals there, once heavily exploited but now numbering over a hundred thousand.

scholarly journals The rat problem on oceanic islands—research is needed

Oryx ◽  
1986 ◽  
Vol 20 (2) ◽  
pp. 79-86 ◽  
Author(s):  
N. M. Wace
Keyword(s):  
Oceanic Islands ◽  
South Atlantic ◽  
Conservation Strategy ◽  
The South ◽  
World Conservation ◽  
Tristan Da Cunha ◽  
Gough Island ◽  
Small Team

In October 1983 a rat was reported to have been seen on Gough Island, an outlier of the Tristan da Cunha Group in the South Atlantic. Gough Island has no permanently resident human inhabitants, but supports one of the largest and most diverse assemblages of breeding seabirds now remaining anywhere in the temperate zones. The author was a member of a small team of biologists that spent three weeks on Gough Island, in October-November 1984, to try to confirm whether there were any rats on the island, and if so to make recommendations for their control and extermination. The following proposals result from experience in carrying out this survey, and from writing World Conservation Strategy proposals for Oceanic Islands for the IUCN.

scholarly journals Benthic Assemblage Composition of South Atlantic Seamounts

2021 ◽  
Vol 8 ◽  
Author(s):  
Amelia E. H. Bridges ◽  
David K. A. Barnes ◽  
James B. Bell ◽  
Rebecca E. Ross ◽  
Kerry L. Howell
Keyword(s):  
Benthic Communities ◽  
Oceanic Islands ◽  
South Atlantic ◽  
Environmental Drivers ◽  
Suitable Habitat ◽  
Benthic Assemblage ◽  
The South ◽  
Diverse Range ◽  
Assemblage Composition ◽  
Tristan Da Cunha

Seamounts and oceanic islands rise from the seafloor and provide suitable habitat for a diverse range of biological assemblages including Vulnerable Marine Ecosystems (VMEs). Whilst they have been the focus of some work globally, there has been little description of the biological and physical environments of seamounts in the South Atlantic Ocean. In this study, we characterized benthic assemblage composition from 13 seamounts and oceanic islands spanning 8–40°S within the exclusive economic zones (EEZs) of Ascension Island, Saint Helena and Tristan da Cunha. Drop camera imagery was collected between 170 and 1000 m. All fauna present in images were identified and quantified, and multivariate statistics were used to describe biological assemblages and identify their environmental drivers. Benthic communities of temperate regions (Tristan da Cunha archipelago) were shown to be distinct from those found in the tropics, with latitude and depth identified as key environmental drivers of assemblage composition. Our results are consistent with the current understanding of the biogeography of the South Atlantic, both in terms of the distinction between tropical and temperate regions, and the influence of depth and water mass structure on assemblage distribution. Faunal assemblages are similar to those observed in the North Atlantic in terms of functional groups. VMEs are present within the EEZs of all three territories and are potentially protected from some threats by large marine protected areas (MPAs). Our imagery, data and analyses provide a baseline for south Atlantic seamounts so that future monitoring can establish whether existing protected status is sufficient to conserve both unique biodiversity and considerable potential for vital ecosystem services.

Gondwanorchestia tristanensis gen. nov. sp. nov., a new southern hemisphere genus and species of talitrid amphipod (Amphipoda, Senticaudata, Talitridae)

Zootaxa ◽  
2020 ◽  
Vol 4748 (2) ◽  
pp. 375-381
Author(s):  
JAMES K. LOWRY ◽  
ALAN A. MYERS ◽  
JORGE PÉREZ-SCHULTHEISS
Keyword(s):  
Atlantic Ocean ◽  
Southern Hemisphere ◽  
New Genus ◽  
South Atlantic ◽  
South Atlantic Ocean ◽  
New Genus And Species ◽  
The South ◽  
Tristan Da Cunha

Material collected by the Norwegian Scientific Expedition to Tristan Da Cunha in the South Atlantic Ocean in the years 1937–1938 and later attributed by Stephensen, 1949 to Orchestia scutigerula Dana, 1852 has been re-examined and is described as a new genus and species, Gondwanorchestia tristanensis sp. nov. Orchestia scutigerula Dana, 1852 is transferred to Gondwanorchestia gen nov. and compared with G. tristanensis sp. nov. 

Echinoidea and Holothuroidea (Echinodermata) of the Trindade and Martin Vaz Archipelago, off Brazil, with new records and remarks on taxonomy and species composition

2016 ◽  
Vol 98 (3) ◽  
pp. 521-555 ◽  
Author(s):  
Luciana Martins ◽  
Camilla Souto ◽  
Joel Braga ◽  
Marcos Tavares
Keyword(s):  
Species Composition ◽  
Oceanic Islands ◽  
South Atlantic ◽  
Brazilian Coast ◽  
The South ◽  
Stepping Stones ◽  
Morphological Variations ◽  
Fernando De Noronha ◽  
Brazilian Province ◽  
Oceanic Archipelagos

The degree of isolation of oceanic islands makes these environments an excellent model for evolutionary studies. Proper knowledge of the species composition of oceanic islands, however, is required to better understand evolutionary processes (e.g. speciation events). A 3-year survey in the shallow waters (up to 30 m) of the Trindade and Martin Vaz oceanic insular complex, and a literature review on the data published for these islands and for Fernando de Noronha and São Pedro and São Paulo oceanic archipelagos have been conducted to document the biodiversity of echinoids and holothuroids from these isolated Brazilian oceanic islands. Sixteen species were collected and characterized morphologically, including two first records for the South Atlantic and one for Brazil. Comparison with conspecific specimens from the Brazilian coast and congeners was also done. Species richness increased from six to 18; the richness in Trindade Island being the highest among the South Atlantic oceanic islands. However, these islands remain undersampled beyond 30-m depth. Endemism was very low, suggesting the potential role of oceanic currents and seamounts as stepping-stones in transoceanic dispersal of species to remote islands. The Brazilian oceanic islands are impoverished oceanic outposts of the Brazilian Province; nevertheless, endemic species and intraspecific morphological variations compared with the mainland suggest they may also be regions of speciation. Documenting their biodiversity is critical for effective management and conservation of their marine ecosystems.

scholarly journals Oceanic Long-distance Navigation: Do Experienced Migrants use the Earth's Magnetic Field?

2001 ◽  
Vol 54 (3) ◽  
pp. 419-427 ◽  
Author(s):  
S. Åkesson ◽  
P. Luschi ◽  
A. C. Broderick ◽  
F. Glen ◽  
B. J. Godley ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Satellite Telemetry ◽  
Oceanic Islands ◽  
South Atlantic ◽  
Common Mechanism ◽  
Brazilian Coast ◽  
The South ◽  
Long Distance ◽  
Green Turtles ◽  
Ascension Island

Albatrosses and sea turtles are known to perform extremely long-distance journeys between disparate feeding areas and breeding sites located on small, isolated, oceanic islands or at specific coastal sites. These oceanic journeys, performed mainly over or through apparently featureless mediums, indicate impressive navigational abilities, and the sensory mechanisms used are still largely unknown. This research used three different approaches to investigate whether bi-coordinate navigation based on magnetic field gradients is likely to explain the navigational performance of wandering albatrosses in the South Atlantic and Indian Oceans and of green turtles breeding on Ascension Island in the South Atlantic Ocean. The possibility that magnetic field parameters can potentially be used in a bi-coordinate magnetic map by wandering albatrosses in their foraging area was investigated by analysing satellite telemetry data published in the literature. The possibilities for using bi-coordinate magnetic navigation varied widely between different areas of the Southern Oceans, indicating that a common mechanism, based on a bi-coordinate geomagnetic map alone, was unlikely for navigation in these areas. In the second approach, satellite telemetry was used to investigate whether Ascension Island green turtles use magnetic information for navigation during migration from their breeding island to foraging areas in Brazilian coastal waters. Disturbing magnets were applied to the heads and carapaces of the turtles, but these appeared to have little effect on their ability to navigate. The only possible effect observed was that some of the turtles with magnets attached were heading for foraging areas slightly south of the control turtles along the Brazilian coast. In the third approach, breeding female green turtles were deliberately displaced in the waters around Ascension Island to investigate which cues these turtles might use to locate and return to the island; the results suggested that cues transported by wind might be involved in the final stages of navigation.

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