The Marine Environment of the Pitcairn Islands - Pew Environment ...

More documents

Recommendations

Info

Head 1 body text Plate 27. The ‘Ocean Fish’ Pitcairn Islands stamp issue from 2007 depicting six species of open-water fish regularly caught off Pitcairn. Top row, from left to right: dogtooth tuna Gymnosarda unicolor; wahoo Acanthocybium solandri; mahi-mahi Coryphaena hippurus; bottom row, from left to right: yellowfin tuna Thunnus albacares; giant trevally Caranx ignobilis; bonito Sarda chiliensis lineolata. array of gastrointestinal, neurological and cardiological symptoms with treatment options being ineffective or very limited (Dickey and Plakas, 2009). In particular, the coral reefs of Mangareva in the Gambier Islands hold large amounts of the dinoflagellate Gambierdiscus toxicus, a ciguatoxin precursor which attaches itself to algae and traverses the food chain bioaccumulating in carnivorous fin fish. High subsequent and ongoing rates of intoxications by ciguatera recorded in the Gambier Islands have been associated with French nuclear testing in the area around Moruroa Atoll and associated military infrastructure development on Mangareva conducted during the period 1968 to the mid-1970s, although the environmental pathways to the outbreak have not been established. While the existing presence of ciguatera is a potential barrier to the development of small-scale commercial fisheries in the Pacific Islands more generally, the Secretariat of the Pacific Community has proposed that the Pitcairn community may be in a good position to develop their inshore reef fisheries commercially for export to Mangareva (Michel Blanc, pers. comm., Nov. 2011), although the purchase and installation of a blast freezer will be necessary to ensure production meets food safety regulation standards. However, as yet no assessment of stocks has been undertaken and the economics of such a venture have to be studied in detail. 20 17. ‘Nearshore waters’ here are defined as extending to approximately 2 km from low water mark or shallower than the 100 m depth contour. 18. Note that Sargassum odontocarpum was originally recorded as Sargassum coriifolium by Tsuda (1976). The taxonomy of the genus Sargassum in French Polynesia was revised in 2008 (Mattio et al., 2008). 19. The Foraminifera (“hole bearers”), or forams for short, are a large group of amoeboid protists which are among the commonest plankton species. They have reticulating pseudopods, fine strands of cytoplasm that branch and merge to form a dynamic net. They typically produce a test, or shell, which can have either one or multiple chambers, some becoming quite elaborate in structure. These shells are made of calcium carbonate (CaCO3) or agglutinated sediment particles. About 275,000 species are recognised, both living and fossil. They are usually less than 1 mm in size, but some are much larger, with the largest species reaching up to 20 cm. [Wikipedia entry, 24Nov11. URL: en.wikipedia.org/wiki/Foraminifera]. 20. Note that only eight species of Foraminifera were listed from all four Pitcairn Islands by Palomares et al., 2011. 21. Ostracoda is a class of the Crustacea, whose members are sometimes known as seed shrimps because of their appearance. Some 65,000 species (13,000 of which are extant taxa) have been identified, grouped into several orders. Ostracods are small crustaceans, typically around 1 millimetre in size. Their bodies are flattened from side to side and protected by a bivalve-like, chitinous or calcareous carapace or ‘shell’. Ecologically, marine ostracods can be part of the zooplankton or (most commonly) they are part of the benthos, living on or inside the upper layer of the seafloor. 22. The figure of 47 species consists of 28 named species, three new genera and 16 new species (Whatley et al. 2004). 23. (http://library.puc.edu/pitcairn/studycenter/ cruiseship.shtml, last accessed 7/12/2011). 3.2 Henderson KEY FACTS Name HENDERSON Island type Elevated coral atoll Location 24°21’S, 128°19’W Distance/bearing from nearest island(s) The Marine Environment of the Pitcairn Islands: Pitcairn The Marine Environment of the Pitcairn Islands: Henderson Approx. 200 km ENE of Pitcairn; and approx. 360 km W of Ducie Dimensions 9.6 km long x 5.1 km wide Land area 43 km 2 (4,310 ha)* Altitude Sea level to approx. 33 m Length of coastline 26.4 km Origin of name European discovery by Pedro Fernandez de Quiros, who passed without landing in 1606 and named it San João Baptista. Received current name in 1831 after it was visited by the British ship Hercules in 1819 under Capt. Henderson. From 1819–1831, however, it was known as Elizabeth Island. Population/visitors Uninhabited. Occasional 2–3 day visits by Pitcairners to harvest miro wood for carving. A stopoff for a few cruise ships (e.g. World Discoverer), whose passengers land for 2–3 hours on North Beach. Status World Heritage Site (1988); Endemic Bird Area; Important Bird Area; Alliance for Zero Extinction site (Brooke, 2010). Proposed Ramsar site (2005). Overview One of the least disturbed raised coral atolls in the world, with its terrestrial ecosystems largely intact. The island supports a large breeding population of seabirds, including the endemic Henderson petrel Pterodroma atrata and also has four endemic landbirds, one of which is a flightless rail. The beaches and reef flats are important for wintering bristle-thighed curlews Numenius tahitiensis. An attempt was made to eradicate rats from the island in 2011 but this was unsuccessful. (Information extracted from various sources including the RSPB’s A Directory of Wetlands in Oceania: http://www.wetlands.org/RSIS/WKBASE/OceaniaDir/Pitcairn.htm) * Updated figure for land area obtained in 2011 using GPS. Previously, the figure was 37 km2 (3,700 ha) (RSPB, Henderson Island Restoration Project). Figure 8. Henderson Island (after Irving, 1995). Plate 29. (right) East Beach, Henderson. (Photo: R.A. Irving) Plate 28. Aerial view of the north end of the East Beach, Henderson. (Photo: SPSCEPI) 21
3.2.1 Introduction Henderson Island is a raised coral atoll composed of coralline limestone (makatea). The island consists of a flat plateau, some 30 m above sea level, densely covered by 6 m-high scrub with a slight depression in the centre where there was once a lagoon. The island is surrounded by steep bare limestone cliffs, with sandy beaches present off the north, east and north-west coasts. The island has no surface freshwater except for some droplets which occur in caves. Fresh or brackish springs have been located below high tide level at North Beach and North-West Beach. No readily available source of groundwater has yet been located. The surface of the island is largely reef rubble, with some areas of dissected limestone, especially around the periphery. There is a fringing reef averaging 50–100 m in width around most of the island except in the south and west. In three places, North Beach, North-West Beach and East Beach, the reef extends up to 200 m offshore and is backed by a wide, gently shelving coral sand beach over bedrock which is partly exposed. The reef off the East Beach has a poorly developed lagoon; those off the North and North-West beaches are seawardly sloping reef platforms without a well-defined reef crest. There are two narrow channels through the reef on the north and northwest coasts. Tides are semi-diurnal, with a tidal range at spring tides of approximately 1.5 m. On 1 January 1989 Henderson Island was inscribed into the UNESCO World Heritage List under the 1972 Convention concerning the Protection of the World’s Cultural and Natural Heritage. 3.2.2 Intertidal zone – habitats and species Henderson has a reef platform adjacent to its North and East Beaches and, to a lesser extent, off the North-West Beach. The near-horizontal platform ranges from 20–40 m wide at the North-West beach; 40–75 m wide at the North Beach; and 40–90 m wide at the East Beach (Irving, 1995). At low water on spring tides, large areas of smooth horizontal rock are exposed at these beaches. Narrow (
Page 1 and 2: The Marine Environment of the Pitca
Page 3 and 4: First published in Great Britain in
Page 5 and 6: Executive summary The extent of the
Page 7 and 8: No. of marine species in major taxo
Page 9 and 10: 1767 and named it Pitcairn’s Isla
Page 11 and 12: 6 Taxon Pitcairn is the only island
Page 13 and 14: 2.3 Measures of protection The UK O
Page 15 and 16: level heights). A Memorandum of Und
Page 17: TURTLES Two species of turtles are
Page 21 and 22: Head 1 body text Plate 36. An aggre
Page 23 and 24: 3.3.1 Introduction Oeno consists of
Page 25 and 26: 3.4.1 Introduction Ducie is a small
Page 27 and 28: Offshore waters 25 4 4.1 Introducti
Page 29 and 30: 4.4.2 Commercial Since 1993 there h
Page 31 and 32: Cross, S. & Pienkowski, M. (eds) 19
Page 33 and 34: Appendix 3: IUCN Red List Species T
Page 35 and 36: Appendix 4: Scientific research exp
Page 37 and 38: Species Authority* Common name (if
Page 39 and 40: Species Authority* Common name (if
Page 41 and 42: Species Authority Common name (if k
Page 61: Robert Irving Terry Dawson Robert i

The Marine Environment of the Pitcairn Islands - Pew Environment ...

Create successful ePaper yourself

Delete template?

Save as template?