. Also the
year of emergence of the nanai signifies yabaki ni sautu, i.e. a year of plenty from
their agricultural produce. The tobu ni nanai, a sacred natural pool which provides
the final resting place for these endemic cicada is also located within the Nasa
catchment. The nanai also bears a national significance; it is the insect that is featured
on Fiji’s highest legal tender note ($100), an acknowledgment of the magnitude of its
Discussion and recommendations
The Emalu forest is of great significance as it harbors a good population for one of
Fiji’s rare and endemic butterflies, H. inopinata, owing to the pristine nature of its
habitat i.e. one of Fiji’s last remaining primary forests. More importantly, it is home
to one of Fiji’s rare and localised endemic cicada, Raiateana knowlesi (nanai) that has
both cultural significance (as the totem of the mataqali Emalu) and national
significance (as featured on Fiji’s $100 note).
This area is also significant for the Odonates (i.e. damselflies) which recorded a good
diversity along the Nasa Creek, Wainisiga stream, Wainikutukutu stream and
adjacent tributaries. This included the genus Nesobasis
which is endemic to Fiji and
has radiated successfully in Fiji having a total of 36 species, a few of which are
currently new to science. With extensive sampling targeting this group within this
pristine inland forest of the Navosa Province
, it is suspected that there may still be
species new to science within the Emalu area. This however warrants further
With an overall high diversity of insects, it further suggests that ecosystem services
provided by the abundant and diverse Coleoptera (beetles, 26 families) and
Formicidae (ants) are well represented with forests systems being quite intact. These
groups of insects have proven to be excellent indicators of the forest and water
systems and their abundance and richness further suggests that much of the Emalu
forest area is pristine.
Sampling efforts within the study sites were compromised due to adverse
(rainy) weather conditions in some areas. A long-term monitoring and
seasonality study of the insects in Emalu is recommended.
The results of this suvey in terms of this area’s insect diversity and the
presence of focal and iconic species strongly support that Emalu be identified
as a Key Biodiversity Area for Fiji.
A total of ten species of fish from eight genera and six families were recorded in the
Emalu site through sampling and interviews. Three species were documented from
the Gobiidae family (Awaous guamensis, Sicyopus zosterophorum, Sicyopterus
). In addition two species of eels from the family Anguillidae were also
collected (Anguilla marmorata
and Anguilla megastoma
) as well as the freshwater snake
eel from the family Opicthidae (Lamnostoma kampeni
). Mavuvu mid reach had an
exceptionally high abundance and biomass of jungle perch (Kuhlia rupestris)
compared to other streams in Fiji. Also documented were the introduced exotic
species tilapia (Oreochromis niloticus)
family Cichilidae. Notable absences around the
headwaters of Nasa Creek were the gobies Stiphodon
and the monkey river
prawn Macrobrachium lar
. No endemic species were observed or caught during this
survey. Water quality was well within habitable range in terms of dissolved oxygen,
conductivity, temperature and turbidity across all sampling stations. The introduced
spp.) are present in mid and lower reach sites and may account
for the low abundance and diversity of native stream fishes. Around areas of human
habitation there is evidence of the removal of riparian buffer zones as well as
unrestricted livestock access to waterways which, coupled with uncontrolled slash
and burn activity has exacerbated environmental degradation in these areas. The use
roots (a traditional fish poison) is also a common problem seen throughout
the survey area. Reforestation of buffer zones and the setting of a riparian buffer
width for agricultural or development purposes are reccommended.
The freshwater fishes of the Fiji Islands have only been extensively studied in the last
decade, by various researchers that have discovered species new to science and
elucidated some of the various factors affecting these insular fish assemblages
(Jenkins and Boseto, 2005, Boseto, 2006, Boseto and Jenkins, 2006, Jenkins, 2009,
Jenkins and Mailautoka, 2010, Larson, 2010, Jenkins and Jupiter, 2011). On a global
scale the freshwater fishes of Fiji have been recently recognised in terms of endemic
species per unit land area (Abell et al
., 2008). The oceanic islands of the Pacific are
distinct from continental land masses in that they have developed unique freshwater
fish assemblages that have important ecological linkages between marine and
freshwater environments (McDowall, 2008a). In Fiji, 166 species (47 families) have
been recorded from tidal reaches upwards, with 156 of these (43 families) indigenous
to Fiji (Jenkins, 2009). Ten species (4 families) have established invasive or non-
indigenous populations in the wild although at least fifteen non-indigenous species
have been introduced (Jenkins, 2009). At least eleven species (in 3 families), which
constitute 7% of freshwater fish in Fiji, are considered endemic.
This survey constitutes the first documented work carried out on freshwater fishes
for Nasa River, but work has been undertaken previously in neighbouring water
systems. King (2004) documented several species of fish and invertebrates in the
neighboring Solikana stream. The species documented by her were Kuhlia marginata
(eels), gobys (Gobiidae family), Oreochromis
, O. mossambicus
(tilapia) and an eel. The eel that King recorded as
is most likely Lamnostoma kampeni
Invertebrate species such as several crustacean species of Macrobrachium
(Paleomonidae) were also noted by King (2004). In the lower reaches of the Sigatoka
River, Fowler (1953) based on two badly damaged specimens described a presumed
endemic genus of freshwater fish collected from hoof print puddles Lairdina
, (Eleotridae, Fig. 31). However the voucher specimens have since been
redescribed and this species is now known as Giuris margaritacea
The Mavuvu River drains into the Navua River, where previous research by Jenkins
& Boseto (2003) within the Upper Navua River Conservation Area documented
thirteen species, including two Fiji endemic species i.e. Redigobius leveri
, and an introduced species Oreochromis mossambicus.
Due to the remoteness of the study area, several methods of gathering data were
used. The field methods described herein were designed to enable the most
comprehensive documentation of fishes present in Emalu. A portable Global
Positioning System (Garmin eTrex 20) was used to take the position and altitude of
the sampling sites. A map of the study area and several pictures of the locations
sampled are provided (Map 9, Fig. 35 - Fig. 38).
Before fishing commenced water quality parameters were recorded to minimise
disturbances to in-situ water quality characteristics. Temperature, pH, conductivity,
salinity and dissolved oxygen were measured using a commercial hand held GPS
Aquameter and AP-1000 Aquaprobe.
In-stream fish sampling
The beach seine (3m x 2m, 1mm mesh) was set several meters downstream and held
by two people. Upstream, one person kicked and dislodge rubbled to enable the
collection of bottom dwelling fish. This was done for about an hour, over
approximately a 100m stretch of stream. To get a thorough documentation of species
presence or absence, snorkeling was also undertaken in streams sampled. This was
also aided by visual observations on the side of the stream bank, as some species of
the gobies are easily distinguishable due to their bright colors. Opportunistic
collections and interviews with villagers were also documented.
Voucher specimens were collected, fixed in a 10% formalin solution and transferred
to 70% ethanol solution after five days of fixation. Voucher specimens were
deposited at the University of the South Pacific marine collection.
Results and discussion
Species richness and abundance
Overall a total of six species of fish were directly observed or collected during this
survey (Appendix 13). There was high species richness near villages compared to the
headwaters of Nasa stream. This is characteristic of insular systems of Oceania where
this attenuation in species richness with increase in altitude has been documented by
Jenkins & Jupiter (2011). Three of the species collected were from the Gobiidae family
i.e. Sicyopus zosterophorum
(Fig. 32), S. lagocephalus
and Awaous guamensis.
two species of eels (family Anguillidae) were also collected, Anguilla marmorata
The jungle perch, Kuhlia rupestris
, was also collected. A further
four species were documented from village interviews as being present in the area
i.e. Kulia marginata, Oreochromis niloticus, Eleotris fusca,
and Lamnostoma kampeni.
Upper reaches of the Nasa stream
The headwater sections surveyed ranged in altitude from 500-570m. The freshwater
fish found at this altitude are characteristic of upper catchments on oceanic islands of
the Indo-West Pacific. The native species Sicyopus zosterophorum
and S. lagocephalus
found here are known as amphidromous fish in which the adults spawn in
freshwater, fertilised eggs hatch within a period of 48 hours. Larvae are transported
to the sea for several weeks of growth and then return upstream (as post-larvae or
juveniles) to complete their lifecycle (McDowall, 2008b). These two species are hardy
fish and are ubiquitous in geographic range. Both are capable of surmounting large
barriers such as waterfalls and can survive in degraded catchments.
There were also two native species of catadromous eels found at this altitude
and Anguilla megatsoma
). Catadromous species are those in which
adults migrate to sea to breed. The juvenile eels then return upstream for more
feeding and growth before returning to sea to complete their lifecycle (McDowall,
2008a). On the last day of the survey a total of 55 eels were caught by villagers (Fig.
30) in Wainirovurovu stream. It is highly likely that traditional fish poison (Derris
roots) were used to catch these eels.
The use of traditional fish poison and other chemicals occurs in inland fishing
communities. A study undertaken in Nawairabe Village (about 10 km west of Emalu)
found that 2.2% of households blamed the use of Derris
roots and other fish-
suffocants for the depletion of fish but “excessive burning (46.7%); and the associated soil
erosion in the wet season (17.8%) were by far the most important environmental problems in
” (King, 2004).
Mid to lower reaches of the Emalu area within and outside the boundary
There were no mid and lower reach sites sampled during this survey though some
visual observations around Navitilevu settlement found the native goby S.
. Informal interviews with villagers recorded native species such Kuhlia
marginata, Awaous guamensis, Eleotris fusca, Lamnostoma kampeni
and the introduced
tilapia Oreochromis niloticus
. The presence of these species can only be confirmed
using proper survey techniques such as electrofishing around this site.
A total of eleven jungle perch Kuhlia rupestris
(Fig. 33) were caught around mid
Mavuvu. The size of these fishes ranged from 11 to 39cm. This mid-reach site just
below the waterfall is traditionally known as sukasuka ni ika droka, a natural barrier
to fish migration (Fig. 34). Only those species adapted to climbing are able to
surmount such barriers. This area within Emalu is an important area in terms of fish
biomass and strict measures must be taken to protect it from over-fishing and
unsustainable practices such as the use of Derris
Results of the on-site measurements are tabulated in Appendix 14. Temperature at
the sites was between 19.7°C and 20.4°C. Dissolved oxygen levels were fairly high,
above 8mg/L, making it readily available for fish at the six stations sampled.
Conductivity at all sites ranged from 0.047-0.084µS which is well within the suitable
habitat range for stream fish. Turbidity was very low at all sites (<10 NTU), and the
bottom was visible at all the stations.
Conclusion and recommendations
The proper management and use of aquatic resources in Emalu entails a holistic
approach due to life-history strategies employed by aquatic fauna that traverse
different habitats throughout their life. It is true that management must begin at the
catchment level; however, it goes hand in hand with the protection of marine and
coastal habitats such as reefs, seagrass meadows, mangrove habitats, including lower
and mid sections of rivers and streams. This survey did not find any endemic
species, for several reasons such as degradation of buffer zones along mid-reach
sites, the high number of introduced species such as tilapia which is known to prey
on the larval species of native fauna and the possible use of Derris
roots in the
The following are suggestions for the proper management and conservation of
aquatic fauna in Emalu:
The first priority is protection of the catchment areas of the Sigatoka River.
The headwaters should be set up as a protected area with a complete ban on
slash-and-burn techniques around the catchments.
Secondly, the other major issue identified is the importance of restoring buffer
zones around mid-reach sites. This will also require the proper education of
farmers (landowners) on setting up farms near rivers, and the importance of a
buffer width and restricting livestock access across streams.
A complete ban should be in place on the use of poison for fish capture. Derris
roots, weedicides and pesticides should be banned in Emalu.
The need for proper waste management care. In the three villages visited
use of flush toilets is strongly recommended. Villagers have running tap water
and flush toilets should be implemented for all households.
Pit toilets in the village need to be built away from the stream. The majority of
the toilets seen across the villages are built on sandy areas within the vicinity
of the stream and are directly leaching into the stream.
A total of 76 freshwater macroinvertebrate taxa were identified from the 16,370
specimens collected. Of these 76 taxa, a total of 57 (75%) were endemic to Fiji, most of
them insects. A total of fourteen macroinvertebrate taxa were selected as potential
bioindicators. These include four species of mayfly larvae (Ephemeroptera: two
spp. and two Cloeon
spp.); two species of damselfly larvae (Odonata:
“dark green”); four species of caddisfly larvae
“light green”, Hydrobiosis
; one cranefly larvae (Tipulidae: Tipula
sp.); one snail (Fluviopupa
spp.); one nematode worm (unknown species) and one moth larvae (Lepidoptera:
unknown species). The high number of endemic taxa recorded, together with a large
number of species with large populations, is indicative of the intactness of both the
stream system and the surrounding forest.
The freshwater macroinvertebrate fauna of Fiji is currently represented by 45
families, namely; 25 families of insects, eight families of molluscs, four families of
crustaceans, three families of segmented worms, two families of nematodes, two
families of sponges, and one family of flatworms (Haynes, 1988, Haynes, 1999,
Haynes, 2001, Jeng et al
., 2003, Haynes, 2009). Many of these are yet to be fully
described to genus and species level and many aquatic insect larvae need to be
matched with their described flying adults.
Prior to this study, no surveys had been carried out to identify the composition of
macroinvertebrate communities within the waterways of this study site or their
tributaries. There is, however, some documentation of previous macroinvertebrate
surveys in other waterways of Viti Levu.
Three tributaries of the upper Sigatoka River (which is located about 23km from
Emalu) were surveyed for possible effects of the Sigatoka-Ba hydropower dam.
Damselfly and mayfly species were noted to be of very sensitive nature to this
development (Haynes, 2004).
In Namosi province macroinvertebrate composition from an unlogged catchment
drained by Wainikovu Creek (23km from Emalu) was compared to that of
Nabukavesi Creek in a logged catchment. After five years, the abundance of
invertebrates in both streams was the same except Nabukavesi Creek had lost five
species which had been present in sparse populations prior to logging and
Wainikovu Creek had more species of an endemic genus of damselfly, Nesobasis
(Haynes, 1999). A survey of Lake Monasavu revealed the presence of damselfly
spp.) prior to dam construction. But eight years after the dam
construction, the damselfly nymph species were wiped out (Haynes, 1994).
These studies were conducted in areas outside the Emalu catchment boundary.
Therefore the present study represents the first detailed and comprehensive study of
freshwater macroinvertebrates and aquatic habitat within the three catchments of
Emalu; Tovatova, Mavuvu and Waikarakarawa.
The key objectives of the study were:
To provide a comprehensive list of taxa.
Describe community structure.
Identify taxa that are unique, rare and endangered in Fiji.
Identify taxa that can be used as indicators of environmental changes.
This report also provides information relating to water physiochemistry and
invertebrate habitats which will assist with interpretation of freshwater
macroinvertebrate results and identify potential areas of monitoring interest related
to the identified biological indicative taxa.
During the first phase of the Emalu survey (July 2012), three main stations were
sampled within Tovatova catchment inclusive of the upstream Nasa Creek and its
tributary, Wainirovurovu Creek. During the second phase of the survey (March
2013), six main stations were sampled within the Mavuvu and Waikarakarawa
catchments, including the headwaters of Mavuvu River (Qalibovitu stream), the Mid
Mavuvu River (Wainasoba Stream) and Waikarakarawa Creek. The descriptions of
the sampling stations are summarised in Appendix 15 and their locations shown in
The area is densely forested with numerous tributaries connected to the main
riparian systems; Nasa Creek and Mavuvu River. The mid to upper portion of the
Nasa Creek is a medium to high gradient undisturbed stream with well vegetated,
highly stable bank and good or moderate canopy cover providing suitable habitat
conditions for thriving freshwater community. The mid Mavuvu River tributary
(Wainasoba Creek) and upper Mavuvu River tributary (Qalibovitu Creek) are
undisturbed waterways with well-vegetated, stable to highly stable banks and good
or moderate canopy cover, providing suitable habitat conditions for thriving
Water physiochemical parameters were measured at each sampling station using a
calibrated multi-water quality meter (Aquaread AV 1000). Parameters measured
included temperature, dissolved oxygen (DO), conductivity (milisiemens per
centimeter (mS/cm), pH, Total Dissolved Solids (TDS), turbidity (Nephelometric
(NTU)) and salinity.
Habitat characteristics and aquatic flora
Habitat characteristics were assessed along 20m reaches per site to assist with
interpretation of macroinvertebrate community data. The following habitat data was
either measured or visually estimated and recorded on a standard habitat assessment
Wetted width and water depth
– channel width (m) was measured using a 30m
measuring tape. Water depth (m) at wadeable sites was measured using a calibrated
meter ruler or estimated at sites that were too deep (i.e. >1m
– velocity was calculated by timing how many seconds a specimen
bottle cap took to travel over a set distance of three metres. This procedure was
repeated three times and averaged to give a mean velocity for each site.
– the relative proportion of each habitat type (e.g. run, riffle, pool and
chute) present at each site was visually estimated.
– streambed substrate composition was assessed at each sampling
station. Assessment procedure involved measuring approximately 100 sediment
particles following the Wolman scale (Wolman, 1954). Size classes included bedrock,
boulder (>256mm), large cobble (128-256mm), small cobble (64-128mm), large gravel
(32-64mm), medium-large gravel (16-32mm), small-medium gravel (8-16mm), small
gravel (2-8mm) and sand/silt (<2mm). Gravel size classes were combined into a
single gravel class (2-64mm) for easier data presentation.
– this involved visual characterisation of streambank stability at
each site as (i.e. stable, partially stable or unstable).
Organic matter present
– observation of woody debris, leaf litter and detritus at
sampling stations. This provides an indication of potential food availability for
certain macroinvertebrate functional feeding groups or additional stable habitat.
Riparian character and channel shade
– at each sampling station, a general assessment of
percentage channel shade and the riparian vegetation characteristics was carried out.
Periphytons (algae) – visual estimation of present streambed periphyton cover
(%) and type
(i.e. film, mat, filamentous) and colour (i.e. green, light brown, dark brown, reddish)
at wadeable sampling sites.
Macrophytes (aquatic plants)
– an assessment of macrophyte streambed cover and
species present at sampling stations