Academic literature on the topic 'Amirante Islands (Seychelles)'

Baited Remote Underwater Video Stations (BRUVS) are widely used for monitoring relative abundances of fishes, especially sharks, but only the maximum number of individuals seen at any one time (MaxN) is usually recorded. In both the Cayman Islands and the Amirante Islands, Seychelles, we used photo-ID to recognise individual sharks recorded on BRUVS videos. This revealed that for most species the actual numbers of separate individuals (IndN) visiting the BRUVS were significantly higher than MaxN, with, for example, ratios of IndN to MaxN being 1.17 and 1.24 for Caribbean reef, Carcharhinus perezi, and nurse, Ginglymostoma cirratum, sharks in the Cayman Islands, and 2.46 and 1.37 for blacktip reef, C. melanopterus, and grey reef, C. amblyrhynchos, sharks, respectively, in the Amirantes. Further, for most species, increasing the BRUVS deployment period beyond the 60 min normally used increased the observed IndN, with more than twice as many individuals in the Cayman Islands and >1.4 times as many individuals in the Amirantes being recorded after 120 min as after 60 min. For most species, MaxN and IndN rose exponentially with time, so data from different deployment periods cannot reliably be compared using catch-per-unit-effort (CPUE) calculated as catch-per-unit-time. In both study areas, the time of first arrival of individuals varied with species from <1 min to >2 h. Individually identifiable sharks were re-sighted after up to 429 days over 10 km away in the Cayman Islands and 814 days over 23 km away in the Amirantes, demonstrating that many individuals range over considerable distances. Analysis of Cayman re-sightings data yielded mean population estimates of 76 ± 23 (SE) and 199 ± 42 (SE) for C. perezi and G. cirratum, respectively. The results demonstrate that, for sharks, the application of both photo-identification and longer deployment periods to BRUVS can improve the precision of abundance estimates and provide knowledge of population size and ranging behaviour.

Two new species from the Indian Ocean are described, Eviota notata and Eviota springeri. Eviota notata has a completecephalic sensory pore system (pattern 1), a dorsal/anal fin-ray formula of 7/7, some branched pectoral-fin rays, and threeprominent dark transverse marks on the nape. Eviota notata is known from the Seychelle Islands, Mauritius, and ChagosArchipelago. Eviota springeri lacks the IT pore belonging to cephalic sensory pore system pattern 2, has a dorsal/anal fin-ray formula of 8/7, unbranched pectoral-fin rays, and a small fifth pelvic-fin ray. Eviota springeri is known from the Sey-chelle Islands, Mauritius, Chagos Archipelago, and the Amirante Islands. An Errata concerning the type material of Eviota atriventris Greenfield & Suzuki is presented.

Abstract A new distribution map is provided for Pulvinaria psidii Maskell. Homoptera: Coccoidea, Coccidae (green shield scale, guava mealy scale). Attacks Citrus, coffee, mango and many other trees and shrubs. Information is given on the geographical distribution in Africa, Aldabra Island, Algeria, Amirante Islands, Angola, Ascension Island, Canary Islands, Cape Verde Islands, Egypt, Eritrea, Farquar-Providence Islands, Ghana, Ivory Coast, Kenya, Madagascar, Malawi, Mauritius, Mozambique, Nigeria, Réunion, St. Helena, Seychelles, South Africa, Sudan, Tanzania, Tunisia, Uganda, Zaire, Zimbabwe, Asia, Bangladesh, Bhutan, Brunei, Cambodia, China, Guangdong, Henan, Hubei, Hong Kong, India, Bihar, Gujarat, Karnataka, Kerala, Maharashtra, Orissa, Tamil Nadu, Uttar Pradesh, Indonesia, Java, Sulawesi, Sumatra, Japan, Kazan-retto, Malaysia, Sabah, Sarawak, West Malaysia, Nepal, Ogaswara-shoto, Philippines, Sikkim, Singapore, Sri Lanka, Taiwan, Thailand, Australasia and Pacific Islands, Australia, Australasian Capital Territory, New South Wales, Northern Territory, Queensland, Caroline Islands, Cook Islands, Fiji, Hawaii, Irian Jaya, Kiribati, Mariana Islands, Marshall Islands, New Britain, New Caledonia, New Zealand, Niue, Papua New Guinea, American Samoa, Western Samoa, Society Islands, Solomon Islands, Tonga, Tuamotu, Tubai, Vanuatu, North America, USA, Alabama, Florida, Georgia, Mississippi, Missouri, New York, Pennsylvania, Washington DC, Central America and Caribbean, Antigua, Bahamas, Barbados, Bermuda, Costa Rica, Cuba, Dominican Republic, Grenada, Guadeloupe, Jamaica, Mexico, Montserrat, Puerto Rico, St. Kitts, St. Vincent, Trinidad, Virgin Islands, South America, Brazil, Brasilia, Sao Paulo, Guyana, Venezuela.

Abstract Background Sharks are in severe global decline due to human exploitation. The additional concern of emerging diseases for this ancient group of fish, however, remains poorly understood. While wild-caught and captive sharks may be susceptible to bacterial and transmissible diseases, recent reports suggest that shark skin may harbor properties that prevent infection, such as a specialized ultrastructure or innate immune properties, possibly related to associated microbial assemblages. To assess whether bacterial community composition differs between visibly healthy and insulted (injured) shark skin, we compared bacterial assemblages of skin covering the gills and the back from 44 wild-caught black-tip reef sharks (Carcharhinus melanopterus) from the Amirante Islands (Seychelles) via 16S rRNA gene amplicon sequencing. Results Shark skin-associated bacterial communities were diverse (5971 bacterial taxa from 375 families) and dominated by three families of the phylum Proteobacteria typical of marine organisms and environments (Rhodobacteraceae, Alteromonadaceae, Halomonadaceae). Significant differences in bacterial community composition of skin were observed for sharks collected from different sites, but not between healthy or injured skin samples or skin type (gills vs. back). The core microbiome (defined as bacterial taxa present in ≥50% of all samples) consisted of 12 bacterial taxa, which are commonly observed in marine organisms, some of which may be associated with animal host health. Conclusion The conserved bacterial community composition of healthy and injured shark skin samples suggests absence of severe bacterial infections or substantial pathogen propagation upon skin insult. While a mild bacterial infection may have gone undetected, the overall conserved bacterial community implies that bacterial function(s) may be maintained in injured skin. At present, the contribution of bacteria, besides intrinsic animal host factors, to counter skin infection and support rapid wound healing in sharks are unknown. This represents clear knowledge gaps that should be addressed in future work, e.g. by screening for antimicrobial properties of skin-associated bacterial isolates.

The sicklefin lemon shark Negaprion acutidens is a large-bodied (> 3m) coastal shark species, widely distributed in tropical and sub-tropical Indo-Pacific waters. Despite its large size and wide distribution, very little is known about its movement behaviour throughout ontogeny. The primary aim of this thesis was to gain an understanding of the movements of sub-adult N. acutidens, in and around the St. Joseph Atoll, Republic of Seychelles, to facilitate the effective conservation of this vulnerable species. A total of 22 sharks (139 – 202 cm TL) were equipped with coded acoustic transmitters and passively monitored using moored acoustic receivers for a period of 20 month from March 2009 to October 2010. The use of passive acoustic telemetry arrays to study behavioural ecology has increased in popularity in recent years and been successfully applied to study a host of teleost and elasmobranch species in a diversity of habitats, ranging from sheltered estuaries to the offshore pelagic environment. However, the practicalities of designing an effective network of receivers to optimally monitor animal movements can be challenging. In this study the receiver array was optimised through a series of incremental steps to achieve an efficient design that allowed for the specific objectives to be addressed. The specific objectives of this study were to i) gain an understanding of the long term space use patterns and site fidelity of sub-adult N. acutidens within degree of use of the St. Joseph Atoll lagoon and surrounding habitats, and ii) investigate their short term behavioural patterns in response to natural rhythmic cycles. The important role the atoll plays in the sub-adult stage of this species was demonstrated by the very low numbers of detections outside the atoll compared to the very large numbers of detections inside the atoll. Over the course of a year the tagged sharks showed a high degree of site fidelity to the atoll, with 79 – 100% of the individuals detected during each month and 50% being detected on a near daily basis. This result provides testimony of the nursery role of the atoll and importance of these habitats in the early life history for this species. Individual area use was generally found to be restricted to the eastern part of the atoll incorporating a portion of the central deep lagoon and a nearby adjacent area of the sand flats. The movements of sub-adult N. acutidens on and off of the shallow flats surrounding the central lagoon (likely for foraging) were found to be strongly influenced by the tidal height and the diel cycle. Tagged sharks were found to utilise the flats more regularly when the tidal height was greater than 90 cm and particularly more so during the night and early morning than during daylight times. The combined results of this study expose the vulnerability of this species to rapid local depletion. Similarly, the effectiveness of spatial management measures, such as no-take marine protected areas is highlighted as an efficient tool for the future conservation of this species. In the St. Joseph Atoll in particular, the use of a multi-levelled protection approach, where the eastern portion on the atoll is completely restricted while the remaining area is utilized for non-consumptive tourism activities, could be highly effective. Future research should investigate changes in area use throughout the ontogeny of this species as well improve the understanding of the breeding site fidelity and population size of reproductive females using the St. Joseph Atoll.