"Hotspots" in Fiji
Findings of an Expedition to the Lomaiviti Group
WWWF - SOUTH PACIFIC CURRENTS
October-November 2001 edition
By Sangeeta Mangubhai
PO Box 10135, Bamburi, Mombasa, KENYA
smangubhai@africaonline.co.ke
Fiji holds 3-4% (i.e. 10,020km2) of the world's coral reefs, placing
it in the top 10 of the 80 countries and geographical locations with
reefs (UNEP-WCMC 2001). While the exact number of coral reefs is currently
unknown, it is believed that there are at least one thousand different
reefs in Fiji's waters (Zann, 1992). Most authors find it difficult
to describe Fiji's coral reefs because of the scattered and very limited
scientific data available. However, a number of scientists have recognised
Fiji's coral reefs as being of high ecological significance from a
biodiversity standpoint (Zann et al. 1997).
The Fiji Government drafted a National Biodiversity Strategy Action
Plan (NBSAP) in 1999 to meet Fiji's obligations under the international
Convention on Biological Diversity, and demonstrate its commitment
to preserving the country's biodiversity. The draft NBSAP specifically
provides for the protection of marine biodiversity and has listed
a number of sites that are considered of 'national significance'.
However, many of these sites listed may represent areas where the
reefs are more known or where scientists have chosen to study in the
past due to their accessibility, rather than those that are truly
important from a national biodiversity perspective. The relevance
of sites nominated for Marine Protected Area (MPA) status needs to
be re-examined nationally, especially in the aftermath of mass coral
bleaching event in the year 2000 (Cumming et al. review).
Coral bleaching is a term used to describe the "whitening"
of coral during periods of stress (such as persistent high seawater
temperatures), and can lead to decrease survivourship of the coral
and death. Coral bleaching has become the primary threat to coral
reefs around the world (Wilkinson 2000; Goreau et al. 2000). Fiji
experienced its first bleaching event in 2000, during the months February
to June, when seawater temperatures remained above the 28.3ºC
expected maximum. These elevated temperatures resulted in the bleaching
of corals on reefs around Viti Levu and south of Vanua Levu. The state
of Fiji's reefs following this bleaching is still not fully described.
While it can be argued that bleaching is a natural response to stress,
it has not been witnessed on the spatial scale as we have witnessed
within the last 3-4 years. The World Wide Fund for Nature (WWF) has
focused its conservation efforts both globally and in the Pacific
in promoting the value of biodiversity and the management tools available
to address increasing threats to coral reefs. The development of any
sort of management regime requires an understanding of the components
and functioning of the ecosystem itself, its limitations and its ability
to respond to threats such as wide-scale bleaching events.
To support in-country efforts to identify marine areas of high national
significance following the 2000 bleaching, WWF coordinated and assisted
in undertaking rapid assessment surveys in April 2001, in the poorly
studied Lomaiviti Group located east of the main island of Fiji, south
of Vanua Levu. The geographical location, size and overall logistics
makes access to this island group difficult and costly from a research
perspective, requiring an innovative approach, partnering conservation
science and dive tourism, to open up access to remote locations. WWF,
in collaboration with NAI'A Cruises Fiji (a live-aboard dive operation),
undertook a 7-day expedition to collect scientific information on
the biodiversity and status of coral reefs in Fiji's Lomaiviti Group.
To obtain as larger a coverage of reefs as possible, rapid assessment
techniques were used to record the diversity and health of reef habitats
and reef life in the Lomaiviti Group, in the aftermath of the 2000
bleaching event. The information obtained will also allow comparisons
with more studied reefs such as the Great and North Astrolabe Reefs
in the Kadavu Province, for which recent baseline data was also collected
(Obura and Mangubhai, in prep.).
Surveys were conducted on SCUBA at 18 sites located in Eastern Bligh
Waters (Vatu-I-Ra Passage), Namena Barrier Reef and waters surrounding
Wakaya and Gau Islands. The study found highly diverse and a complex
range of reef types including seamounts, bommies, barrier reefs, pinnacles
and more typical reefs types, such as patch and channel-edge reefs.
Fan and tree-shaped soft corals dominated vertical walls, steep slopes
and deeper sites, while carpeting soft coral forms dominated shallower
waters. The variety of shapes, textures and colours reflected the
richness of soft coral species found in the Lomaiviti group. Unfortunately,
the taxonomic complexity and difficulty in identifying soft corals
prevented an estimation of the species diversity of this group and
hence requires further studies.
Hard corals, in comparison dominated shallow and horizontal surfaces
with 127 species recorded during 7 days of diving. This figure is
consistent with species numbers in other parts of Fiji. Coral mortality
resulting from the 2000-bleaching event was evident by the amount
of dead skeletons (0-50%), the high coverage of coralline algae, turf
algae and rubble. However, hard corals in this island group appeared
to have been more resilient to the 2000 bleaching event relative to
other reefs in Fiji, where mortality rates of 60%, and as high as
100%, were recorded. Some bleaching (<10%) was recorded in these
2001 surveys though with low to zero mortality.
According to scientists from the University of the South Pacific,
the algae community was taxonomically typical of Fijian reefs with
all 46 species previously recorded for Fiji. Mobile invertebrate populations
(e.g. sea cucumbers, giant clams and other molluscs, starfish, lobsters)
were generally low reflecting the types of habitat available and possibly
high rates of predation from healthy fish populations. Sedentary invertebrates
such as sponges, ascidians, and bivalves were abundant. Fish populations
were generally large and diverse, with abundant schooling plankton-feeding
and pelagic fish, indicating low fishing pressure. The presence of
a diversity and abundance of fish species is likely to have played
an important role in the control of the proliferation of algae following
the 2000 bleaching. Sharks and large groupers were generally low,
though significant grey reef shark aggregations were observed at two
sites. Only four hawksbill turtles were observed during the surveys.
Ten of the 19 sites surveyed during this expedition were identified
as being important for one or more of the animal groups that were
surveyed. Along with the great range of reef types recorded, this
indicates that the region as a whole has a complex assemblage of coral
reefs and reef fauna, and that further surveys of this nature, and
of more systematic ecological nature, are necessary to adequately
sample the diversity of the area.
The findings of this study supports the importance of the reefs of
the Lomaiviti group nationally, and the need to develop a conservation
and management regime, involving customary resource owners, managers,
national decisions makers, the tourism sector and other stakeholders,
to ensure the long-term protection of the biodiversity in this region.
Of particular significance in the national context, the reefs in the
Lomaiviti Group displayed a certain level of resilience to bleaching,
are hence is likely to play an important role in providing refugia
and reseeding adjacent reefs in Fiji more widely damaged by coral
bleaching and global climate change. Key hard coral sites such as
those found in the Lomaiviti Group may require some level of conservation
management as an "insurance policy" against climate change
related degradation such as happened in 2000, and was repeated on
a lesser scale in 2001.
While low human population numbers and geographic isolation of the
Lomaiviti Group have helped to maintain the ecological integrity of
coral reefs in the area, local communities are facing the challenge
of adapting to the new forces of development and globalisation, and
climatic impacts such as mass coral bleaching. The greatest long-term
security for the communities of the Pacific will be achieved through
sustainable, adaptive local management.
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