Biomonitoring Of Coral Reef Health Using Butterfly Essay, Research Paper

Biomonitoring of coral reef health using Butterflyfishes (Family: Chaetodontidae) Ryan Gounder 11/6/99 THE INDICATOR HYPOTHESIS “Coral feeding Butterflyfishes respond to declines in coral quality or abundance by behavioral and spatial adjustments that can be easily and rapidly observed.” (Crosby & Reese 1996) Introduction A fundamental question that one asks when using Chaetodontidae, or for thatreason any species as biomonitors is: why use an organism whensophisticated machines are available to detect very small quantities ofpollution in short space and time? One might think that biomonitoring hasbecome redundant because of these machines, but the opposite is true,chemical monitoring tells us what is there, but not its effects -especially long term effects on ecosystems therefore biomonitoring hasbecome a preferred method of assessing ecosystems (Spellerberg 1993). The conditions required for healthy coral reef growth as well as factorscausing damage to reefs are well understood (Reese 1981). Usually acuteenvironmental impacts on coral reefs can be easily assessed (Brown 1988).However it is not as simple when it comes to chronic sublethal factors.Using conventional methodologies the overall health of a coral reef canbe determined against a baseline study (Brown 1988). But it is of no-usebecause the damage has already been done, that is why indicators of sublethal are urgently required so stress can be detected early, andcounter-measures put forth (Brown 1988, Reese 1981, Hourigan et al 1988).In this essay the use of Butterflyfishes as indicators of reef health willbe discussed. What are Butterflyfishes? Butterflyfishes are consipicious, largly dirunal fishes ranging typicallyfrom 10 – 20 cm in length (Sale 1991). There are 114 species ofButterflyfishes world-wide (Crosby & Reese 1996), thirty five found in Fiji(Seeto 1999). The name Chaetodontidae is derived from Greek “khaite”,meaning hair and “odont-” meaning tooth (Allaby 1991). They are, perhapswith some disagreement, the most beautiful fishes on coral reefs. Watchinga Butterflyfish on the reef is an awesome acrobatic like performance! Theirsheer colourfullness, beauty and apparent will to let people comephysically close to them make this group of fishes rather special (personalexperiences and observations). The body shape helps Butterflyfishes escape from predators (Seeto 1999,Allen at al 1998). When Butterflyfishes are viewed from the side, theimpression one gets is that they are comparatively large, but as the fishmove to front view they almost disappear because their bodies are socompressed (personal observations and experience). Its significance is thatButterflyfishes are able to live relatively long lives partly because oflack of predators (Seeto 1999), making them even better indicators of reefhealth. Furthermore Butterflyfishes are either home-ranging or territorial (Reese1989). What this means is that the Butterflyfishes live out their lives inthe same area of coral reefs unless there is any stress. Butterflyfisheshave a life span up to 10 – 12 years depending on species and have beenobserved on the same territories for seven to eight years (Reese 1991). Itssignificance is that since the Butterflyfishes are always relatively in thesame area they will “feel” the stresses and respond accordingly (Crosby &Reese 1996, Why use Butterflyfishes as Biomonitors? There are many species of Butterflyfishes that have co-evolved with coralsand are obligate corallivores (Reese 1981, 1991 Harmelin-Vivien &Bouchon-Navaro 1983). The metabolic or energy demand of these species areso “intimately linked” to the health of the corals that these species haveexcellent potential as indicators of changes on coral reefs (Crosby & Reese1996). Crosby and Reese (1996) have described four important reasons whyChaetodontidae are potentially good indicators: Scientific names of corals and fishes are not required to be known by the data collectors. Suggested species for Fiji are in Appendix 1. Information collection can be stepwise, example, the first step could be counting the Butterflyfishes along the transect and the next step could be counting the corals. This method allows the matching of time, recourses and personal available. Butterflyfishes are best used where there is gradual, chronic (sublethal) disturbances which would be difficult to measure by alternative methods, example, collection of tissue and water samples for analysis. However this method is not appropriate for catastrophic disturbances, example, oil spills, storms, etc. Lastly, it is environmentally friendly, relatively cheap, nondestructive and non-consumptive method that does not require technical scientific training thus can be used by volunteers, local communities and individuals. Practical Application of Butterflyfishes as Indicator Species Crosby and Reese (1996) propose a 8 step process in the application of thismethod. Firstly the problem has to be assessed, the question asked clearlyidentified and the goals of the monitoring program stated. The second isfield observations, since the Butterflyfishes are directly observed – it isnecessary to have scuba diving equipment. The third step involves the establishing of transect lines. Transect linesare placed in sections of approximately 30m. They are placed purposefullyin areas of high coral cover since change in living coral cover andbehavior of Butterflyfishes are of interest. The data is recorded on underwater paper. Usually data sheets arephotocopied on underwater paper to make recording of data easier. Howeversometimes the underwater paper has to be run through the copy-machine twice(See appendix 2) to get a good result (Reese 1999). Step four involves counting and recording the numbers of each species ofButterflyfish within five meters of the transect lines (See Appendix 2).This method is known as the Belt Transect Census Method and is reviewed byBrock (1982). Step five involves the estimation of coral cover along the transect lines.Data is again recorded on underwater data sheets (see Appendix 3). In thesixth step the territory boundary is marked and the chasing behavior

measured (see Fig 2 and appendix 4). The seventh step is the measuring of the feeding behavior and the size ofthe territory (see appendix 5 & 6). The size of the territory is estimatedby measuring the territories to the left and right of the transect line andthen the area in square meters is calculated (see appendix 6). The eightstep is like a clean-up operation, all the equipment (transect lines,colour-tagged nails, etc) are removed. However in order to return to thesame site, accurate coordinates must be recorded. The final step is the analysis of the data. A comprehensive data analysisdescription with examples can be found in Crosby and Reese (1996). Howevercorrect data analysis depends on an understanding of the design of themonitoring program (Crosby and Reese 1996). However in a nutshell under stressful conditions some of the behavioralchanges that is expected: The amount of chases will increase because theButterflyfishes will try to find more food in their neighbors territories,the territory sizes will change and also the feeding rates will change(Crosby and Reese 1996). Conclusion The one major conclusion that can be made from this study is that the useof Butterflyfishes as indicators of coral reef health may be an excellenttool for the assesment of reefs in the South Pacific Region. This isbecause the use of Butterflyfishes for this purpose is cheap and requiresrelatively less resources than other methods. APPENDIX 1 (compiled from: Reese 1991, Crosby & Reese 1996) Possible Indicator Species of Butterflyfishes from Fiji region Species marked with an asterisk (*) are particularly promising indicators. * Chaetodon baronessa occurs from Cocos-Keeling Island in the Indian Ocean,east to Fiji, north to Japan, and south to the GBR. It is replaced by C. Triangulum in the rest of the Indian Ocean. Where these species are abundant they are excellent choice because of their relatively small territory size. Feeds on Acropora. Feeding mode: Specialist. Chaetodon plebeius occurs from the Andaman Sea in the eastern Indian Ocean,extending eastward to Fiji, north to Japan and north to the Great BarrierReef. Apparently it is rare or does not occur in Micronesia and Polynesia. * Chaetodon trifascialis (formally: Megaprotodon strigangulus) occurs fromEast Africa eastward to Tahiti and throughout Polynesia to Johnson Atoll ad the Northwest Hawaiian Islands, but not the high islands of Hawaii. It is widespread throughout Melanesia and Micronesia, extends southward to the GBR and northward to Japan. It specializes in feeding on corals of the genus Acropora. * Chaetodon trifasciatus occurs from East Africa eastward tin Polynesia toHawaii and Tahiti. It is widespread in Melanesia and Micronesia. It extends north to Japan and south to GBR. It is replaced in the Red Sea by C. austriacus and by C melapterus in the Persian Gulf. Feeds on Porites. Acropora, Pocillopora when avilable. Feeding mode: Generalist. Literature Cited Alino PM, Sammarco PW, Coll JC (1988) Studies of the feeding preference ofChaetodon Melannotus (Pisces) for soft corals (Coelenterate; Octocorallia).Proceedings of the 6th International Coral Reef Symposium. Australia.3:31-36 Allaby M (editor) (1991) The concise Oxford Dictionary of Zoology. OxfordUniversity Press. Oxford Allen GR, Steene R, Allen M (1998) A guide to Angelfishes andButterflyfishes. Odyssey Publishing/Tropical Reef Research. Australia Brock RE (1982) A critique of the visual census method for assessing coralreef fish populations. Bulletin of Marine Science. 32:296-276 Brown BE (1988) Assesing environmental impacts on coral reefs. Proceedingsof the 6th International Coral Reef Symposium Burgess WWE (1978) Butterflyfishes of the world: a monograph of the familyChaetodontidae by Dr Warren Burgess. TF Publishing Inc Ltd Crosby MP, Reese ES (1996) A Manual for Monitoring Coral Reefs withIndicator Species: Butterflyfishes as Indicators of Change on Indo PacificReefs. Office of Ocean and Coastal Resource Management, National Oceanicand Atmospheric Administration. Silver Spring MD. 45pp Davidson OG (1998) The Enchanted Braid – coming to terms with nature oncoral reefs. John Wiley & Sons, Inc. New York Gomez ED, Licuanan WY, Hilomen VV (1988) Reef fish-benthos correlations inthe Northwestern Philippines. Proceedings of the 6th International CoralReef Symposium. Australia. 3:245-249 Gore MA (1984) Factors affecting the feeding behaviour of a coral reeffish, Chaetodon capistratus. Bulletin of Marine Science. 35(2):221-220 Hourigan TF, Timothy, Tricas C, Reese ES in Soule DF, Kleppel G – [editors](1988) Marine Organisms and Indicators. Springer-Verlag New York Inc Rapport D, Costanza R, Epstein PR, Gaudet C, Levins R (1998) EcosystemHealth. Blackwell Science Inc. USA Roberts CM, Ormond RFG, Shepherd ARD (1988) The usefulness ofButterflyfishes as environmental indicators on coral reefs. Proceedings ofthe 6th International Coral Reef Symposium. Australia. 2:331-336 Reese ES (1973) Duration of residence by coral reef fishes on “home” reefs.Copeia NO 1:145-149 Reese ES (1981) Predation on corals by fishes of the family Chaetodontidae:Implications for conservation and management of coral reef ecosystems.Bulletin of Marine Science 3(3) 594-604 Reese ES (1989) Orientation behavior of Butterflyfishes (FamilyChaetodontidae) on coral reefs: spatial learning of route specificlandmarks and cognitive maps. Environmental Biology of Fishes Vol25(1-3):79-86. Kulwer Academic Publishers, Dordrecht Reese ES (1991) How behavior influences community structure ofButterflyfishes (Family Chaetodontidae) on Pacific Reefs. EcologyInternational Bulletin 19: 41 Reese ES (1999) Correspondence via E-mail and “Snail” mail. Correspondencewith Author. Department of Zoology. Edmonsdon Hall 2538 The Mall.University of Hawaii at Manoa. Honolulu, Hawaii 96822 Spellerberg IF (1993) Monitoring ecological change. Cambridge UniversityPress Vivien-Harmelin ML, Navaro-Bouchon Y (1981) Tropic relationships amongChaetodontid fishes in the Gulf of Aquaba (Red Sea). Vivien-Harmelin ML, Navaro-Bouchon Y (1983) Feeding diets and Significanceof Coral Feeding among Chaetodontid Fishes in Moorea (French Polynesia).Coral Reefs 2:119-127 White AT (1988) Chaetodon occurrence relative to coral reef habitats in thePhilippines with implications for reef assessment. Proceedings of the 6thInternational Coral Reef Symposium. Australia. 2:427-432