DIVERSITY OF REEF FISH FUNGSIONAL GROUPS IN TERMS OF CORAL REEF RESILIENCES

Copyright © 2016, Indonesian Fisheries Research Journal (IFRJ) Available online at: http://ejournal-balitbang.kkp.go.id/index.php/ifrj e-mail:ifrj.puslitbangkan@gmail.com INDONESIANFISHERIESRESEARCHJOURNAL Volume 22 Nomor 2 December 2016 p-ISSN: 0853-8980 e-ISSN: 2502-6569 Accreditation Number: 704/AU3/P2MI-LIPI/10/2015 Diversity of Reef Fish Fungsional Groups in Terms of Coral Reef Resiliences (Edrus, I.N., & M. Abrar)


INTRODUCTION
Coral reefs were known as fish habitats where some ecological niches exist to support various fish functions in coral reef ecosystem.Some functions will collapse in damaged coral reefs due to lost of ecological niches (Jones et al., 2004).Such as in unfavourable circumstances of the coral reefs, there are some losses of reef fish species and others remain to survive occupying the areas due to adapting capability.Unhealthy habitat conditions commonly derived from changes in coral covers and poor body waters as a result of sedimentation and run off from main land (Jones & Syms 1998).
Land based run off as an external factor could contribute a significant influence to community structures, functional composition of reef fishes and coral life (Mallela et al., 2007;Manthachitra & Cheevaporn, 2007).According to Amesbury (1981), there was a significantly relationship between abundance or diversity of reef fishes and water transparency that are depending on accumulative deposit of sedimentation transport by fluvial processes.Some studies were also indicated that there is significant relationship between reef fish abundance, spesies diversity and live coral coverages, which reef fishes considerable changed community structures and loss diversity particularly due to hardcoral cover dwendling.(Halford et al., 2004;Jones et al., 2004;Graham et al., 2006;Wilson et al., 2006).
Decreasing in enviromental quality has lead to negative impacts to Seribu Island coral reefs throughout the last three decades 2005 to 2007 surveyed generaly indicated that 4.2 % of coral covers were declined (Terangi, 2007).The negative impacts of development in Jakarta Bay likely and its adjacent waters likely produced substantial chemical pollutant, sediment, and domestic wastes (Suprapto et al., 2011).In addition, marine resort and property development in Tengah Island of Seribu Islands and massive coastal reclamation in the areas that directly influenced body water quality and generates poor impacts on status of local coral reef communities.All of the activities were predicted as local stressors for Pari reef areas, therefore it is needed to measure changes of fish community structures in this specific area.
Changes in bottom substrate may affect to the reef ecosystem services.Hence, it is important to monitor the coral reefs capacities that are be able to support intensely to reef fish communities in the Pari Islands.The changes may influence to community structures and then these changes will sequentially influence to nature of reef biota growth.Changes of coral cover take place due to settlement modification of reef fishes that have special functionsin food web as well as increasing in harbivorous reef fish families as a grazer group controling macroalgae growth for new recruitment of hard corals, or due to unfrendly fishing as well (Green & Belwood, 2009).Grazing fishes have abilities to adjust substrates on coral reef by using positively or negatively ways.Fish habitat and fish communities may disturb each other and in turn lead to coral reef resilience depending on herbivorous reef fishes.In food web, carnivore fishes may control the herbivore fishes, and the other hand, fishing activities may reduce fish population, especialy carnivore group such as groupers, snappers, sweaplips (Obura & Grimsditch, 2009).
Resilience is the ability of a system to absorb or recover from disturbance and change, while maintaining its functions and services.For example a coral reef's ability is to recover from a bleaching event (Grimsditch & Salm, 2006).According to Obura & Grimsditch (2009), the resilience is not only take place under damaged coral reefs condition, but also naturaly takes place in vigorous-coral reefs.Reef fish communities have capability to maintain or modify coral structures for its be sustainability.One of critical resilience factors is fish species and functional diversity.For this reason, It is essential to recognize functional groups of fishes supporting resilience processes of coral reefs.Resilience assessments could help to provide an early warning of decreases of its important resilience drivers.
Recently, there are three available methods for assessing pre-disturbance coral reef resilience, i.e.Obura & Grimsditch (2009), Maynard et al. (2010), andBachtiar et al. (2011).This study is a part of Obura & Grimsditch (2009) method that only put emphazes to a roles of fish functional groups, especially herbivorous fishes.Diversity, density, composition and sizes of the fishes are substantial quality indicators from which they could be used directely on readily avaibale collected data and those in part of assessment on coral reef resilience in order to make management priority in a reef area already damaged (Obura & Grimsditch, 2009;Thibaut et al., 2008;Hughes et al., 2007).
This study aimed to gather selected-resilience indicators, especially variables data on herbivores and other functional groups of fish that exert top-down control on phase shift dynamics on coral reefs.

MATERIALS AND METHODS
Field observation was carried out in very short observation on March 2015 at the waters of Pari Islands, Seribu Island District.The study is addressed to provide information on some parts of quantitative assessment of coral resiliences by using indicators of functional reef fish groups that play a role insupporting coral resilience.
Well known that in coral reef areas there are always specifically interaction or respond of benthic organism each other.In the specific interaction, quantitative sampling can be conducted for functional fish groups such as herbivores, carnivores and omnivores.This study is mostly focused on biological indicators, e.g.
(1) numbers of fish, overal and by functional groups.
(2) abundance/density of the fishes by functional groups and species.(3) composition of fish populations, families and by functional/trophic groups.
A method used for data gathering was standard underwater visual census (UVC) of fish by focusing on herbivore functional groups and including other functional groups of fish (English et al., 1994;Obura& Grimsditch. 2009).
The method focused on census fish at sufficient resolution to allow analysis of individual and by functional group.The level of detail is needed for different functional groups varies from species to family level.Study sites took place inpermanent belt transects (Appendix Figure 1).The cencus area is 70 x 5 m in frame.Fish numbers by species were visually noticed by using waterproof papers.Species identification was determined by referred to pictorial guide of Indonesian reef fishes (Kuiter & Tonozuka, 2001;Allen & Erdmann, 2012).

Data Analysis
The data were listed by kinds of respective fish functional groups that might be indicators for supporting resilience process.The functional groups are the role of fishes in food web, and herbivorous fishes were selected as an example listed in Appendix Table 1.Feeding habits of the herbivorous fishes were separated into four categories (Appendix Table 2) (Berkepile & Hay. 2008;Obura & Grimsditch., 2009).
Preference attending of fish functional groups, such as individual numbers and fish species, were tabulated in scales (rankings) and weighted as basis for resilience indicators that followed tabulation by Obura & Grimsditch (2009).The scale and weight depend on variables of the individual number of reef fish functional groups (adapted from Berkepile & Hay, 2008;Obura & Grimsditch, 2009), such as herbivore (excavator, scarapers dan grazer), predator (piscivores), indicator (coral obligate), and others (invertivore/grazers).The ranking in terms of a character of resilience indicesisa degree based on Obura & Grimsditch (2009) including level from very low (1) to very high ( 5).The indices are derivedfrom interval individual numbers of a fish functional group.The weightwere calculated from cross over between a ranking (1 to 5) and an individual number of fish fungsional groups.According to Obura & Grimsditch (2009), the more increase in a weight value, the higher a functional group infuenced on resilience effects.

RESULTS AND DISCUSSION Results
Finding of underwater visual cencus at three of transect sites of 21 fish species of major functional groups (herbivores) likely played a role on coral reef resiliences, especially, the fish species that are belong to families of Scaridae, Acanthuridae, Siganidae, Pomacanthidae and Kyphosidae. Figure 1 illustrates percentages of the respectively attending families as mention above.The figure shows that Scaridae was the most assertive family as well as Scarus gobban representatively attended in the largest number.All of the fish species found during visual cencus can be seen on the Appendix Table 1.Functional groups such as excavators, scarapers, grazers, browsers, which the species have already described by Obura & Grimsditch (2009),were variably found at the 1 st and 3 rd station of study siteswhere there were 17 species, respectevely; however at 2 nd station was only found 2 species of scraper and grazer groups.The other functional groups that were also considered playing roles in coral resiliences consisted of 13 families (Figure 3), especially those were dominated in all stations by Pomacentridae (grazers) and Labridae (invertivores), the well known families have a usual great number and strong affinity to coral reefs (Appendix Table 4).Major pradator groups were represented by attending families such as rock cods (Serranidae), snappers (Lutjanidae), emperors (Lethrinidae), trevally (Carangidae), goatfishes (Mullidae), spinecheeks (Nemipteridae), sweetlips (Haemulidae), and squirrelfishes (Holocentridae).Some dominant predators families generally found at the 1 st station1 and 3 rd station of cencus areas included spinecheeks (5 species), snappers (4 species), and rock cods (4 species), however the 2 nd station have lower deversityfor predator.In generaly, predator group attended under 5 % for which the persentage composition ilustrates on Figure 2.
An indicator functional group, the coral obligate of Chaetodontidae, was found in lower level.The coral obligates consisted of 5 species for respective transect sites of the 1 st and 3 rd stations, while those in the 2 nd station were found to 1 species only.Their composition was only around 5% of total attending of the other functional species (Figure 2).Data analysis for grouping the reef fishes functions shows that there were four factors controled on coral resiliences and ranged from the high level to low level of intensities (Obura & Grimsditch, 2009), especially the factors derived from existences of herbivores, predators, indicators and other functional groups (Table 1).In both of the 1 st and 3 nd stations, the herbivory influences of an excavator entity included in low level, even those felt to be non effect in 2 nd station.The Scrapers entity is moderately effected in the 1 st station, lowly effected in the 2 nd station and higly effected in the 3 rd station.The grazersor browsers entities are lowly effected in the 1 st station and the 3 rd station, however those very low level effected in the 2 nd station.In generally, herbivores are influenced in low level to resilince works in the 1 st and 3 nd stations, while those include in lowest level in the 2nd station.

Diversity of Reef Fish Fungsional Groups in
Focus on the composition of species identified in the study sites, the species found were small size herbivores, such as Scarusspp., Siganusspp.and Acanthurus spp.which included in a scraper group.The scraper entity haslower effect to resilience works than that for excavators (Obura & Grimsditch, 2009).
The influence of predators (fiscivores) was high level in the 1 st and 3 rd stations, while it was moderate level in the 2 rd station.The influence of indicator fishes of Chaetodontidae family includes in fair level for the 1 st station, very low level for the 2 nd station, and low level for the 3 rd station.The influence of invertivores, especially a damselfish group (Pomacentridae) that also was considered as grazers, included in very high level for all stations, because the damselfishes were highly found in both of species numbers and individual numbers.

Discussion
Reef fish functional groups, such as parrotfishes (Scaridae) and rabbit fishes (Siganidae) found in study area were identified as excavators, scrapers, grazers and browsers, especially those are the most part of herbivores.Green & Bellwood (2009) stated that herbivores considerably played a role in coral reef resilience remedies, because those have a capability to control and reduce algae growing and then replaced it for coral larvae so that new coral recruitment established on substrates given.The herbivorous fishes essentially play a role in competitive interaction between corals and macro algae.Furthermore, the fishes, especially excavators, a reactively actor in coral bio-erosion and able to create a shifting of growing phases between corals and macro algae, that their processes arenot well understand.
For these reasons, management has to put emphases on the herbivorous fish group, because shifting of herbivorous regimes in coral reefs maysignificantly effect on changes of coral substrates (Berkepile & Hay, 2008;Green & Bellwood, 2009).
Unfortunately, herbivore diversity and their abundance found in the study sites was very low level with majority small body sizes.Most of the species found were herbivorous scrapers, while common species in big sizes and extreme excavators such as Bolbometopon muricatum did not appear in the study sites.Small excavators dominantly found in the transect areas were Chlorurus bleekeri and Chlorurus sordidus.Most of scrapers identified in the areas and ranged from juvenile to adult levels were Scarus gobban.Like the parrot fishes and rabbit fishes, also 109-122 added in group of grazers and browser, they were low levels in species and individual numbers.The assertive rabbit fish was only Siganus virgatus.Hence, herbivorous group performances at coral reefs of Pari Islands, even at Pari Lagoon, were relatively insufficient to support coral resilience succession.Their effects might be classified in low and moderate levels.This condition might be non satisfaction of course for ecosystem, based on Thibout et al. (2008), the density and diversity of herbivorous functional group were be important to deal with offering guaranty for sustainable growing of coral reef ecosystems.For this reason, the fish groups performing ecological functions must be steady state in order to control the shifting of reef biota regimes.
A large number of individual and biomass of herbivorous fishes was positively correlated with cover of 'cropped substrata' (i.e., turf, microalgae, or crustose corallines); however, herbivorous fish populations were never large enough to 'crop down' more than about 50 to 65% of substratum (Williams et al., 2001).Under the low level of abundance and/or biomass of herbivorous fishes, such as this study, the level are insufficien to control algae growing and coral recruitment.In the study in Great Barrier Reefs, given the abundance of herbivorous fishes was about 0.49 -0.70 individual/m 2 and biomass was about 0.45 ± 0.08 kg/m 2 , effects of grazing on algae and coral percent cover were never large enough to crop down algae coverages and to rise up coral coverages, whereas algae persent cover was still high in mean 56 ± 21% and coral percent cover was remain in a rank from mean 6.0% ± 0.8% to mean 7.7% ± 1.0%.Furthermore, coral recruitment was mean 39 ± 11 colonies/25 m 2 plot.Otherwise, when given abundance was ranged from 4.19 to 5.99 individual/m 2 and biomass was ranged from 3.15 to 4.5 kg/m 2 , the effects on algae percent cover, coral percent cover, and coral recruitmen were to be positively running in control the subtratum.Algae coverages were croped down to be 1,7% and 4,7%, coral coverages were increased in ranking from 19.2% ± 2.3% to 20.2% ± 2.2%, whereas coral recruiments were rised to be mean 108 ± 26 and 118 ± 21 colonies /25 m 2 plot (Hughes et al., 2007).Some genus of Pomacentridae and Labridae usually found in coral reef areas (Appendix Table 3).Those are dominant composition of reef fish communities, however those did not entirelybe included in herbivorous functional group (grazers).The families of Pomacentridae and Labridae disconformed in assessing coral resilienceisdue to small sizes and wide variety of feeding habits (Obura & Grimsditch, 2009).In Fishbase (Froese & Pauly, 2014), genus of damselfish (Pomacentridae) including in a grazers category and having a feeding territory are Abudefduf, Amblyglyphidodon, Cheiloprion, Chrysiptera, Dischistodus, Neoglyphidodon, Plectroglyphidodon, and Pomacentrus.Abundance of the genus as mention above in the study sites of Pari Islands is catagorized in more high level than those for herbivores of other families.Folowwing to Casey (2012), damselfishes were grazers that usually have a dominant population among other herbivorous fishes for which damselfishes have significant roles to considerably inûuence the recruitment and postsettlement dynamics of corals.
A damselfish being well known with extremely territorial behaviours is attended to aggressively defence its feeding ground from predators or other grazing species that were bigger in body sizes than that for the damselfish itself.The damselûshes also take care their some key behaviours within their authorities such as grazing turf algae, pecking coral polyps to further propagate algae, weeding unpalatable algae species, and constant aggression against intruders to protect resources (Klumpp & Polunin, 1989;Letourneur et al., 1997).The territorial damsefishes cultivate well-definited algal assemblages within their feeding authority and protect them.Hence, the damselfishes may be likely to intensely effect on benthic reef biota (Hata& Kato, 2004;Ceccarelli, 2007).Inaddition,althoughtheterritorialdamselûshesinhabit in a wide variety of coral reef, these fishes are usually abundant on shallow reef crests and growing fringing reef and those may have harmful or favourable affects for establishing juvenile corals (Choat, 1991).
Diversity of Reef Fish Fungsional Groups in Terms of Coral Reef Resiliences (Edrus, I.N., & M. Abrar) Table 1.Effects of functional reef fish group to coral resiliences in the Pari Islands coral reefs

109-122
By analysing juvenile coral communities as a function of the temporal turnover of damselûsh territories, Casey et al. (2015) found that damselûshcoral-algae linkages were highly dynamic in reef crest environments.Previous studies showed that the behaviour of territorial grazers on sheltered back reefs had multifaceted impacts on coral recruitment and survival (Letourneur et al.,1997;White & O'Donnell, 2010).However, according to Casey et al. (2015), the ûndings elucidated the role of territorial damselûshes on the reef crest, which had received much less attention.Thus overall, territorial pomacentrids had a negative impact on juvenile coral abundances; yet, the damselûsh turnover resulted indication of an unexpectedly dynamic system.While juvenile coral abundances could rapidly decline under the cultivation behaviours of a territorial damselûsh, we found that juvenile coral abundance might likewise rapidly recover with the loss of a damselûsh territory.Hence, despite the overall negative inûuence of territorial damselûshes on coral communities, there is potential for coral recovery on reefs occupied by territorial pomacentrids due to these high rates of territorial turnover and subsequent rapid increases in juvenile coral abundances.Corals are sedentary species that are highly sensitive to temporal-spatial shifts in biotic and abiotic regimes (Sandin & McNamara,2012).Consequently, the overall negative impact and the dynamic nature of damselûsh territories on the reef crest have important implications for benthic assemblages on the reef crest.
Another functional group found in the study sites was the carnivory, a top predator in food web, inhabited in reef crasts (1 st Station and 3 rd station) and consisted of economical prospective families such as rock cods (Serranidae), snappers (Lutjanidae), emperors (Lethrinidae), trevally (Carangidae), goatfishes (Mullidae), spinecheeks (Nemipteridae), sweetlips (Haemulidae), and squirrelfishes (Holocentridae).However, density and diversity of the families included in very low level due to lack of species, while individual numbers varied and rangged from 1 % to 5 %.Mostly the predator were small in sizes, its means under 25 cm.It indicated that there was intensively fishing for the predator (Sadovy et al., 2007), for which cumulatively effects migh increase in coral resiliences, especialy due to collectively high controls on other functional groups (Obura & Grimsditch, 2009).
An indicator group of the Chaetodontidae family was discovered in the study sites under lower levels than that in other healt coral reefs (Edrus & Syam, 1998).The dominant species of Chaetodontidae was only Chaetodon octofasciatus indicating high level of sedimentation in the study sites.Other species of Chaetodontidae that migh have individual low levels (< 4 individuals) included Chaetodon collare, Chaetodon lineolatus, Chaetodon speculum, Chelmon rostratus, Heniochus pleurotaenia and Heniochus varius.All of Chaetodontidae species identified in the study sites were included in facultative coralivores and generalist coralivores, thus the Chaetodonts were not included in specialist diet (Pratchett, 2005).Their effects on resiliences ranged from very low to low lavels (Obura & Grimsditch, 2009).The Chaetodonts have a tiny mouth more being preferences to consume coral polyps than that to algae (Reese, 1981), so that their attendance both of species numbers and individual numbers may be insufficience of effecting on coral resilience.

CONCLUSION AND RECOMMENDATION
Reef fish functional groups such as hebivores, carnivores, and indicators that inhabited in Pari Islands, especialy both of density and deversity aspects, migh be classified inadequately state to support for sustainable coral resiliences.In additation, body sizes of the functional groups were included in the lower categories to support resiliences processes, especially there were a lot of the number of tiny grazers and browsers; however, there were a small amount of the excavators.On other hand, piscivores (predators) as competitor of resilience supporting species were found in a quite number.
It's needed to repetitive monitoring on diversity of the fish functional groups and its relationship to newrecruitmen of coral colonies.

Figure 1 .
Figure 1.Major family composition (%) of harbivorous species identified in the three transect sites at the Pari Islands coral reefs.
Figure 2. Family group composition of reef fishes indetified in three transect sites at the Pari Islands coral reefs.