Ecological Assessment of Coral Reef Herbivorous Fish
Assemblages across the Spermonde Archipelago
Aidah A. A. Husain1, Naomi M. Gardiner2
1) Faculty
2)
of Marine Science and Fisheries, Hasanuddin University
School of Marine and Tropical Biology, James Cook University, Townsville, Australia
Abstract
This study aimed to determine the distribution of functional groups of herbivore reef fishes and
their relationship to benthic algal cover. A total of 12 islands representative 3 zones of
Spermonde Islands selected as the study site. Fish observations was conducted by the 50m
transect line, while benthic cover observed by using 1x1m quadrant in the same line transect.
Densities of herbivore reef fishes were classified into 4 functional groups at 3 zone waters.
Analysis of variance was used to see whether there are differences in the distribution of each
functional group to the zone. Analysis of biomass was converted through a long weight formula.
Abundance and biomass of herbivore reef fishes group with benthic algal cover correlation was
done by regression analysis. The results showed that the distribution of abundance and
biomass of herbivore reef fishes in the Spermonde islands were not always depending on the
condition of benthic algae, and there were indications that fishing pressure also contributes. It is
necessary to monitor herbivore reef fish, primarily on functional groups that control macro algae.
Keywords: functional groups, herbivore reef fishes, benthic algae, Spermonde waters
INTRODUCTION
In trophic levels, the coral reef ecosystem meets all tropics elements in complete
and balanced order, hence most of the energy generated in this ecosystem will be
recycled (Kochzius and Khalaf, 2002). It starts from the producer level including various
types of microscopic algae and benthic, the consumer level consisting of herbivores,
omnivores and detritivores, to the top consumers, all generate the trophic pyramid with
important roles on each level. Any change on the composition and amount of each
level might disrupt the balance of the ecosystem.
The herbivores play an important role as the community structure regulator in the
coral reefs. Some surveys in several pristine islands, the Conservation International
(CI) reported that 58-63% of reef organisms were benthic carnivorous, 16-18%
planktivores, 15-17% omnivores and only 8-10% were herbivores (Allen and Adrim,
2003). Even the composition of herbivores is relatively small, they can be a critical
controller since it can suppress the growth of macroalgae and facilitate the recruitment,
growth, survival and resilience of corals (Burkepile and Hay, 2008). Littler et al. (2006)
and Albert et al. (2008) state them as the top-down factors to the abundance of algae,
while the bottom-up controller played by nutrients. McCook (1996) found this
herbivores pressure on the algae growth in the Great Barrier Reef, Australia.
The important role of herbivore fishes has become the main topic of research in
many coral reefs (Hughes et al., 2007; Bonaldo, 2010). Herbivore reef fishes are key
organisms in the ecosystem of the Indo-Pacific coral reefs (Choat, 1991), while in the
Atlantic, played by sea urchins (Bruno et al., 2008). They can maintain the reef health
1
Presented in the Indonesian Project Grants Workshop on 5 November 2014, in the Hedley Building,
Australian National University, Canberra.
which effect the benthic community structure (Vincent et al., 2011). In the waters that
severe with overfishing, abundant benthic algal groups are usually found, and it is
generally due to the lack of herbivore fishes (McClanahan et al., 1996).
The common family of herbivore fishes found in coral reefs are triggerfish
(Acanthuridae), parrotfish (Scaridae), rabbitfish (Siganidae), rudderfish (Kyphosidae)
and batfish (Ephippidae). Both Acanthuridae and Scaridae have greater tasks in
limiting algae growth, as well as cleaning the substrates to provide coral planula larvae
to attach and grow (Bellwood et al., 2004; Mumby et al., 2006). The grazing intensity is
high enough to inhibit the growth of algae in covering the surface of corals (Bellwood et
al., 2004).
The number of herbivore fishes are quite enomerous and various, however from
previous studies, Green and Bellwood (2009) has summarized these fishes it into
several functional groups according to their roles based on feeding habit, food habit,
and their impact on the substrate. Functional group is a group of species that have
similar functions, regardless of the proximity of taxonomy (Steneck and Dethier, 1994).
For reef fish, the functional group is generally synonymous with a collection of species
from different trophic levels in the food chain (e.g. predators and herbivor), which
reflects their role in main energy flow in coral reefs (Bellwood et al., 2004). This
grouping is important in understanding the role of herbivore fishes in the coral reef
ecosystem and build up ecological models to examine the herbivore impact in reef
communities (Burkepile and Hay, 2011). Green and Bellwood (2009) has divided the
these herbivore fishes into four functional groups, i.e. scrapers/small excavators, large
excavators/ bioeroders, grazers/detritivores, and browser.
In recent years, Spermonde Islands waters have suffered with high fishing pressure
and this in turn affect species diversity and abundance (Jompa et al., 2006), especially
on herbivore reef fishes and the algae as their food.
The protection of reef fish herbivor is needed in order to maintain the health of coral
reefs, so the research on reef fish herbivor based functional groups is necessary to
look at the distribution of functional groups herbivor reef fish and benthic algal cover
conjunction with several islands in Spermonde Islands.
METHODS
Sites
This research was conducted in the waters of the coral reefs in 12 of over 100
islands scattered Spermonde Islands in March 2014. Selection of the island by the
zoning by de Klerk (1983), which divides the four zones based on topography and
geomorphology. Furthermore, zoning was modified by Faisal (2012) into 3 zones,
through eutrophication modeling directly related to the presence of benthic algae,
which further relates to the presence of biota herbivor. Zone I consists of 3 islands
(Lae-lae, Laiya, Salemo), Zone II consists of 4 islands (Barranglompo, Bontosua,
Kodingarenglompo, Samatellulompo) and Zone III consists of 5 islands (Lanyukang,
Lumu-Lumu, Reang-Reang, Saranti , Tambakulu).
Herbivore Reef Fishes
Observations of reef fish herbivor performed using a 50-meter transect line, with
repeat 3 times, at a depth of 3-6 meters, mounted parallel to the coastline following the
instructions English et al. (1994). Observations were made of the number and types of
reef fish herbivor, as well as estimates of the total length of each individual category of
reef fish herbivor, by setting the value of the midpoint in each category (Table 1), in an
area of 2.5 meters to the left and right (a total of 5 meters). Once converted distance
measurement, in turn, used to estimate broad transect abundance units (ind/250m2).
As for biomass estimation is done by converting the long relationship the weight of
each species of fish in the Green and Bellwood (2009) which is then converted to units
of kg / ha.
Table 1. The midpoint of each category from total length of herbivore fishes (Green and
Bellwood, 2009).
Category
1
2
3
4
5
6
7
8
Size
5 - < 7.5 cm
7.5 - < 10 cm
10 - < 15 cm
15 - < 20 cm
20 - < 25 cm
25 - < 30 cm
30 - < 35 cm
35 - < 40 cm
Midpoint
6.25 cm
8.7 cm
12.5 cm
17.5 cm
22.5 cm
27.5 cm
32.5 cm
37.5 cm
Benthic Algae Coverage
Observations cover the overall benthic done using quadrant 1x1M on transect lines
previously installed for observation herbivor reef fish. In these transects, data collection
percentage composition of benthic algal cover, live coral, dead coral, sponges and
other organisms as well as the substrate by the method of PIT (point intercept transect)
every 10 meters on the transect line to follow the development of LIPI (2008).
Data Analysis
Abundance of reef fish herbivor translated into 4 functional groups on the 3 zone
waters. Analysis of variance is used to see if there are differences in the distribution of
abundance of each functional group to the zone. Similarly, analysis of biomass, for
which data is converted through a long formula weight of each species with different
constants refer to Green and Bellwood (2009). Furthermore, to see the relationship of
abundance and biomass of reef fish groups herbivor with benthic algal cover performed
by regression correlation analysis.
RESULTS
Herbivor reef fishes observed during the study in Zone I, II and III consists of 48
species and one individual, which is divided into four functional groups herbivor:
browsers, grazers, excavators and scrapers (Figure 1).
Browsers: Acanthurus lineatus (TL 28cm)
Grazers: Siganus vulpinus (TL 19cm)
Excavators: Chlorurus sordidus (TL 20cm)
Scrapers: Scarus ghobban (TL 20cm)
Figure 1. Some species found of each functional group species.
Abundance and Biomass
The distance between the zones with the mainland tend to influence, based on the
average abundance of reef fish herbivor increased from Zone I to Zone III (Figure 2).
Nevertheless, the results of the analysis of variance showed no significant difference
from the average abundance of fish herbivor between zones (P = 0.0692) (Table 2).
Figure 2. Distribution of average abundance and biomass of herbivore fishes in each zone.
Average biomass of reef fish herbivor showed varying trends. Average biomass
from Zone I to Zone II increased almost 2-fold, but then again decreases when heading
to Zone III. Although the average abundance of fish in Zone III herbivor most, but low
biomass. This indicates that the distribution of fish herbivor in the outer zone is mostly
small. Nevertheless, the results of the analysis of variance showed no differences
remained between the zones to the overall biomass (P = 0.3007) (Table 2).
Table 2. Summary results of the analysis of variance or t-test, and further result on significant
difference by Tukey's Post-Hoc test.
Variable
df
F
T
P
Abundance
Browsers
2
0.1597
0.8850
Grazers
2
2.811
0.1126
Excavators
7
Scrapers
2
2.646
0.1248
Total
2
2.849
0.0692
Browsers
2
0.6093
0.5672
Grazers
2
0.4532
0.6493
Excavators
7
Scrapers
2
0.06768
0.935
Total
2
1.226
0.3007
Zone I
2
0.6843
0.5461
*
Zone II
3
3.647
0.0446
*
Zone III
3
4.589
0.0168
Zone I
2
0.2837
0.7644
Zone II
3
0.8376
0.4989
Zone III
3
0.5929
0.6286
0.3406
0.7434
Biomass
2.277
0.0569
Abundance
Biomass
Post-hoc Tukey Test (P<0.05)
Mean Diff.
q
95% CI of diff
Abundance
Zone II
Browsers vs Scrapers
-21.17
4.55
-40.70 to -1.632
Zone III
Browser vs Scrapers
-20.73
5.117
-37.13 to -4.340
The results of the analysis of variance test also remains showed no difference
herbivor abundance and biomass of fish between the zones for each functional group
(browsers, grazers, excavators and scrapers) (Table 2). Although descriptive, look to
the differences on almost all histograms, except the variable "Biomass-Scrapers" that
looks almost the same (Figure 3). Ledlie et al. (2007) previously found no particular
tendency for both abundance and biomass among research locations. However, the
abundance of functional groups browsers and scrapers showed a marked difference in
Zone II (P = 0.0446) and Zone III (P = 0.0168) (Table 2, Figure 4).
Figure 3. Average abundance and biomass of each functional group herbivor fish in each zone.
Figure 4. Average abundance and biomass of each zone for each functional group herbivor fish.
Herbivore Fish Biomass and Benthic Algae Coverage
150.00
60.00
120.00
50.00
40.00
90.00
30.00
60.00
20.00
30.00
10.00
0.00
0.00
Zona
Zone II
Zona
Zone IIII
Zona III
Zone
III
Avergae of Benthic
Algae Cover (%)
Average of Herbivore Fish
Biomass (kg/ha)
Average percentage of the benthic algal cover showed the lowest value in Zone II,
this is different to the average biomass of reef fish are generally higher herbivor in
Zone II (Figure 5). Regression model between each functional group by percentage of
benthic algal cover showed a weak correlation, indicated by low R2 values (0007-0263)
(Table 3). This indicates that the benthic algal cover is controlled by the presence of
fish herbivor, although in this study did not show a significant role.
Browsers
Excavators
Grazers
Scrapers
Alga Bentik
Figure 5. Average biomass of herbivore fishes to average percentage cover of benthic algae.
Table 3. Regression analysis result between the biomass of each functional groups of fish and
percentage of benthic algal coverage.
Equation
R2
Browsers
y = -0.068x + 41.04
0.007
Grazers
y = -0.158x + 49.20
0.263
Excavators
y = -0.137x + 44.51
0.112
Scrapers
y = -0.079x + 45.43
0.136
Fungsional Groups
DISCUSSION
Abundance and distribution of reef fish herbivor can vary spatially along the
coastline, or based on depth, as well as among a variety of reef habitat conditions
(Nemeth and Appeldoorn, 2009). Herbivor reef fish distribution pattern generally
depends among others on the number of individuals and biomass, which have an
impact on changes in benthic (Ledlie et al., 2007).
The distribution of functional groups of reef fish herbivor descriptively show different
abundance and biomass. In Zone I, which is the area near the mainland, found the
average abundance and biomass were the lowest, but it was also found that the
percentage of algal cover the most high. Russ (2003) found a significant positive
correlation between the productivity of algal biomass grazers in the Great Barrier Reef.
However, some of the results of other studies in which it gives a picture of the areas
with high benthic algal cover there is little evidence to indicate that both the number
and biomass of reef fish herbivor increases with an increase in algal turf (Ledlie et al.,
2007). It is actually related to the types of the algae itself, which is divided into several
functional groups based on anatomical and morphological characteristics (Steneck and
Dethier, 1994) and growth form (Diaz-Pullido and McCook, 2008). In Zone I generally
present with a group of macro algae are generally canopy size> 10 mm, which at this
stage most of the types of macro algae have been less desirable for consumption by
the various functional groups of fish herbivor. Only a few species of grazers and
browsers that group can still consume the type of macro algae (Green and Bellwood,
2009).
While in Zone II, it is generally found the highest abundance and biomass, but with
low benthic algal cover. This suggests that predation activity herbivor fairly intensive,
because algal species composition bentiknya still favored, which generally is a type of
benthic algal canopy size generally <10 mm (Diaz-Pullido and McCook, 2008).
As in Zone III, although the highest abundance, but lower biomass, and percent
cover of algae that is also low. This indicates there is still a high intensity of predation
by fish herbivor small. In general, groups of scrapers which are found in this zone,
while browsers and grazers especially large been reduced. Possibility of fishing
pressure on the fish herbivor larger ones could be one cause of reduced fish biomass
in this zone. The arrest of a high activity made possible due the location of these
islands from the mainland, so there is no special control and handling of related parties.
CONCLUSION
Distribution of abundance and biomass of fish herbivor functional groups showed
no significant differences between the zones. However, their abundance showed
differences between the functional groups of reef fish herbivor in each zone, especially
in the middle zone and outer zone.
Herbivor reef fish functional groups contribute to the control of benthic algal cover.
It is necessary for the monitoring of reef fish herbivor primarily on functional groups that
play a role in the control of macro-algae in maintaining the health of coral reef
ecosystems.
Acknowledgements
I would like to thank Dr. Ahmad Faisal, Arham, and Opay for their considerable assitance during
field works, Arniati M.Si for her underwater camera and some equipments, and Dr. Nurliah
Buhari for data processing.
REFERENCES
Albert, S., J. Udy, and I.R. Tibbetts (2008). Responses of algal communities to gradients in
herbivore biomass and water quality in Marovo Lagoon, Solomon Islands. Coral Reefs, 27:
73–82.
Allen, G. and M. Adrim (2003). Coral reef fishes of Indonesia. Zoological Studies, 42(1): 1–72.
Bellwood, D.R., T.P. Hughes, C. Folke, and M. Nyström (2004). Confronting the coral reef crisis.
Nature, 429: 827–833.
Bonaldo, R.M., J.P. Krajewski and D.R. Bellwood (2011). Relative impact of parrotfish grazing
scars on massive Porites corals at Lizard Island, Great Barrier Reef. Marine Ecology
Progress Series, 423: 223–233.
Bruno, J.F., H. Sweatman, W.F. Precht, E.R. SELIG, and V.G.W. Schutte (2009). Assessing
evidence of phase shifts from coral to macroalgal dominance on coral reefs. Ecology, 90(6):
1478–1484.
Burkepile, D.E. and M.E. Hay (2008). Herbivore species richness and feeding complementarity
affect community structure and function on a coral reef. PNAS, 105(42): 16201–16206.
Burkepile, D.E. and M.E. Hay (2011). Feeding complementarity versus redundancy among
herbivorous fishes on a Caribbean reef. Coral Reefs, 30: 351–362.
Choat, J.H. (1991). The biology of herbivorous fishes on coral reef. In: Sale, P.F. (ed) The
Ecology of Fishes on Coral Reefs. Academic Press Inc., California USA. Pp 120-155.
deKlerk, L.G. (1983). Zeespiegels, riffen en kustvlakten in Zuidwest Sulawesi, Indonesie, een
morphogenetischbodemkundige studie. PhD thesis, University of Utrecht, The Netherlands.
Diaz-Pulido, G. and L.J. McCook (2008). Macroalgae (Seaweeds). In: Chin, A. (ed) The State of
the Great Barrier Reef On-line. Great Barrier Reef Marine Park Authority, Townsville.
http://www.gbrmpa.gov.au/corp_site/info_services/
publications/sotr/downloads/SORR_Macroalgae.pdf (Akses: 23 Juli 2008).
English, S., C. Wilkinson, and V. Baker (1994). Survey Manual for Tropical Marine Resources.
Australian Institute of Marine Science, Townsville.
Faizal, A. (2012). Dinamika spasio-temporal pengaruh eutrofikasi dan sedimentasi terhadap
degradasi terumbu karang. Disertasi. Program Pasca Sarjana Universitas Hasanuddin,
Makassar. 270 hal.
Green, A.L. and D.R. Bellwood (2009). Monitoring functional groups of herbivorous reef fishes
as indicators of coral reef resilience – A practical guide for coral reef managers in the Asia
Pacific Region. IUCN Working Group on Climate Change and Coral Reefs. IUCN, Gland,
Switzerland. 70p.
Hughes, T.P., D.R. Bellwood, C.S. Folke, L.J. McCook, and J.M. Pandolfi (2007). No-take
areas, herbivory and coral reef resilience. Trends in Ecology and Evolution, 22(1): 1–3.
Jompa, J. & L.J. McCook (2002). The effects of nutrients and herbivory on competition between
a hard coral (Porites cylindrica) and a brown alga (Lobophora variegata). Limnol.
Oceanogr., 47(2): 527–534.
Jompa, J., A.A.A. Husain, M. Litaay, D. Yanuarita, and C. Richter (2006). Anthropogenic and
natural stresses on coral reefs around Spermonde Archipelago: management challenges for
conservation. Manuscript presented at the 6 th European Meeting of the International
Society for Coral Reef Studies, Bremen, Germany.
Khalaf, M.A. and M. Kochzius (2002). Community structure and biogeography of shore fishes in
the Gulf of Aqaba, Red Sea. Helgol Mar Res, 55: 252–284.
Ledlie, M.H., N.A.J. Graham, J.C. Bythell, S.K. Wilson, S. Jennings, N.V.C. Polunin, and J.
Hardcastle (2007). Phase shifts and the role of herbivory in the resilience of coral reefs.
Coral Reefs, 26: 641–653.
Lembaga Ilmu Pengetahuan Indonesia (LIPI) (2008). Baseline Data Daerah Perlindungan Laut
Kabupaten Pangkep. LIPI-COREMAP II, Jakarta.
Littler, M.M. and D.S. Littler (2006). Assessment of coral reefs using herbivory/nutrient assays
and indicator groups of benthic primary producers: a critical synthesis, proposed protocols,
and critique of management strategies. Aquatic Conserv: Mar. Freshw. Ecosyst.
McCook, L.J. (1996). Effects of herbivores and water quality on Sargassum distribution on the
central Great Barrier Reef: cross-shelf transplant. Marine Ecology Progress Series, 139:
179–192.
Mumby, P.J., C.P. Dahlgren, A.R. Harborne, C.V. Kappel, F. Micheli, D.R. Brumbaugh, K.E.
Holmes, J.M. Mendes, K. Broad, and J.N. Sanchirico (2006). Fishing, trophic cascades, and
the process of grazing on coral reefs. Science, 311: 98–101.
Nemeth, M. and R. Appeldoorn (2009). The distribution of herbivorous coral reef fishes within
fore-reef habitats: the role of depth, light and rugosity. Caribbean Journal Science, 45(2-3):
247–253.
Russ, G.R. (2003). Grazer biomass correlates more strongly with production than with biomass
of algal turfs on a coral reef. Coral Reefs, 22: 63–67.
Steneck, R.S. and M.N. Dethier (1994). A functional group approach to the structure of algaldominated communties. Oikos, 69: 476–498.
Vincent, I.V., C.M. Hincksman, I.R. Tibbetts and A. Harris (2011). Biomass and abundance of
herbivorous fishes on coral reefs off Andavadoaka, Western Madagascar. Western Indian
Ocean J. Mar. Sci., 10(1): 83–99.
Wismer, S., A.S. Hoey, and D.R. Bellwood (2009). Cross-shelf benthic community structure on
the Great Barrier Reef: relationships between macroalgal cover and herbivore biomass.
Marine Ecology Progress Series, 376: 45–54.