ICES 1990 POSTER C.M.1990/L:55 SESSION Q INITIAL PARAMETER ESTIMATIONS OF A CORAL REEF FLAT ECOSYSTEM IN BOLINAO,PANGASINAN NORTHWESTERN PHILIPPINES
by
P.M.Alino, L.T.McManus J.W.McManus, C. Nanola, M.D.Fortes G.C.Trono, Jr. and G.S. Jacinto
Marine Science Institute University of the Philippines P.O. Box 1 Diliman, Quezon City Metro Manila, Philippines
ABSTRACT
Initial parameter estimations for the reef flat around
Santiago Island, Bolinao, Pangasinan were made for 24 subcomponents
input of the ecosystem. Four primary producer groups (Benthic seaweed, seagrass, sessile invertebrates, e.g. corals and
phytoplankton), five invertebrate benthos (sea cucumbers, sea urchins, sessile invertebrate consumers, e.g. coral polyps, • crustaceans and molluscs), 12 commercially important fish groupers,
zooplankton, squids and a detritus box were investigated utilizing
ECOPATH 11. ~easonable estimations of ecotrophic efficiencies were obtained for most of the components. The model helped to indicate
areas for further investigation of the system i.e. biomass estimations of cryptic species and Q/B values for top predators e.g. the moray eel (Gymnothorax pictus). -I
I. INTRODUCTION , Tropical reefs are diverse and complex ecosystems which set a formidable challenge to understand its structure arid function relationships. Ecosystem models such as ECOPATH 11 (Christensen and Pauly, this volume) provide a useful,taol in gaining insights to such systems. These iriitiäl estimations of the Bolinao reef flats h~lp in indicatin~ le~ds foi further refining the quantification of the components, of the systeiri~ The further verification ofits ,inputs arid 6cit~utscan a1so be utilized in various fisheries related decision option arid processes which are important in developing countries' mUltispecies-niUltigear fisheries activities.
II. MATERIALS AND METHODS " A. BACKGROUND OF STUDIES IN BOLINAO REEF COMPLEX Bolinao, Pangasinan is located in the,southwestern corner of 0 Lingayen Gulf in Northwestern Luzon, Philippines at 16 , 25' N latitude and 1190 55' longitude. The Bolinao Marine Laboratory, a field station of the University of the philippines Marine Science Institute (UPMSI), is situated proximal tothereef flat study site referred to in this papei. Most of the sources of iriformation are from the various research projects ofthe Institute, while a few are estimated from other secondary sources cif possibly comparable areas. We present in this section, the various data sources and our computed approximations adopted for the Bolinaoreef flat. The estimated area of the reef flat i5 approximately 24.09 Km2 with an average depth of 2m, dominated by seagrass (deI Norte and Pauly, 1989) • The site is situated in a fringing back reef flat. Scattered coral patches composed of,Pavona decussata,and Porites are present at -10% cover. More detailed descriptions of, the macrobenthic invertebrates ar~ presented, by de Guzman" (1990) • Campos et al (1989) gives an overview of the fishery yields of the area and Nanola et al ,(1989) provides fish visual census estimation. Trono and Lluisma (1990) estimates. standing crop seasonality of the sargassum zone of these reef flats which occupies the area before the coral community crest zone. Initial plankton productivity is being,investigated by L.T. McManus and G. S. Jacinto. The currency of the model inputs are in g. m- 2 wet weight (ww). B. PLANKTON BIOMASS AND PRODUCTIVITY ESTlMATES The average annual zooplankton biomass observed by L~ T. McManus is around 262.1-311.9 mg dry weight (DW) •. We estimate this • to be around 2.87 9 Ww.m- 2 with a P/B ratio of 40.00 ,from a Gross Efficiency of 0.30 (see Christensen and Pauly, this volume. Jacinto made chrorophyll a measurements which gave an av~rage ofO.12 9 DW •m- 3 which we converted to :-0.3 g ,ww•m- 2 and based" on Larkum' s (1983) estimated range of phytoplankton productivity we estimated a productivity of 788 9 ww/m-2/yr and thus giving a P/B = 30.417. C. INVERTEBRATE PRODUCTIVITY AND BIOMASS Sea cucumber z values from Leonardo and Binohlan ( pers. com., unpublished report) were used for P/B values. Gross efficiency was inputed at 0.20 (Christerisen and Pauly, ,this vo1ume). Sea urchin biomass (35.77) was estimated by Trinidad Raa and Pasarnonte (in prep.,pers. corn.) with z at 7.506. Molluscs biomass va1ues were estimated based on Klump and Po1unin's eitima~es for bio~~ss for mac~oi~vertebratei in the GBR, ari~ z values were computed from ELEFAN length frequency information of S~ Luhuanus from Alifto and Licu~nan (pers~ com~). P/B estimates for squids were taken from Balgos (1990) for Sepioteuthis lessoniana. GE for crustaceanswere inputed at ,0~30 (Christensen arid Pauly; this volume); The sessile invei-tebrate consluners biomass estimate of 200 mg was based on an estimate of around 40% of- 500 mg wet weight for coral polyp biomass estimated by Sorokin (1981) for the reef crest in the Great Barrier Reef ~ Sessile invertebrate producer biomass was based on Benson arid Muscatine's (1974) estimateof 45% of the'protein biomass of the Pocillopora damicornis. P/B ratios of sessile invertebrate producers were also estimated b~sed on Sorokin (1981) and the invertebi-ate consumer was adjusted to 0.1 instead of 0.039.
D~ BENTHIC PLANT PRODUCTION AND BIOMASS, . Seagrass biomass of 6.7 (organic matter) and prcductivi~y cf 1.4 C/m2/daywere based from Fortes (1990) thus,we converted it to ~ biomass estimateof 702 9 ww.m- 2 ;yr-1 and a"P/B ratio of 8.43~ We uied an average seaweed estimate of around 823 ~ 19 9 ww; in- 2 based on Trono and Lluisima's (1990) study and an estim~ted productivity 2 1 based on growth studies estimated at 127,770 9 ww.m- .yr- , thus a P/B of 15.34~ E. FISH PRODUCTION AND BIOMASS , , Siganus fuscescens has the, highest biomass oß 35;77g.m- 2 wet weight.based from deI Norte and Pauly's (1990) from virtual population study. Most,of the other reef fish biomass,estimates were based on fish visual cEmsus. (Naftcla et al, 1989). This provided good estimates for fishes in the coral associated species such as Siganus spinus, pomacentrids (damselfish), scarids and Chaetodontids (other omriivorous f ish) • The other cryptic and camouflage fish biomass estimates for those inthe sea grass areas were complemented with night time trawl data. . This ,combined estimates, provides both day and riight biomass estimates; though it has to be noted that the trawl data may give uriderestimated biomasses (C. Naftola, in prep.). F. CONSUMPTION AND EXPORTS Estimated exports were based on fisheries catch data. Invertebrate fish ,catches for sea urchins (gonads=0~26) sea cucu:inber (1.57) and gastropods (2.34) were taken from de Guzman • (1990). Estimates for crustaceans were utilized from.the Coastal Resources Management Project in Bolinao led by L.T. McManus. Fish catch data were, based on the collaborated resources project FSA/CRSP monitoring of Bolinao reef fisheries organized by J.W. McManus. , Food ccnsumption estimates forSiganus fuscescens, .the biggest catch in the area (-40%) was based on (Q/B=124) analysis of the gut content aridevacuation (Hernandez et ale i this volume); Sambilay et al; (1990) provided a good basis for many cf the annual Q/B values in this paper; The following.Q/Bvalues were based on Sombilay et ale (1990): Sea cucumbers(3.83); Crustaceans (based on Shrimp 28;94), siganus spinus (47~92), cardinal fishes (based on ttie soldierfisti Myripristis murdjan =19; 31), groupers=3. 0 (basedon Epinephelus tauvina and E. fuscogutatus = 5.0) and other herbivorous fish (Dascyllus melannurus = 14.53); We recomputed Klump and Polunin's, (1989) ,data ?n stegastes apical~s for damselfishes (Q/B -54.7), parrotfishes (-28.0) and other omn1vorous fishes based on Klump and Polrinin's ,blenny (-30.90) and ~ollu~cs (5.6). We estimated the wrasse Q/B based on its aspect ratio ,of Choerodon ancorago arid W (1.3 Kg) parameters using Paloma~es and Pauly's (1989) . equation with T =27°C~ Other estimates were calculated using the gross efficiency input of 0.30 and 0.20 inputs (see table 1). . G. PREDATION FLOWS . Aside from the diet· composition of Siganus ,fuscescens which is based on gut content analysis of specimens from the study 'site, inputs for the diet compositiori matrix was based from niatt and Strasburg's (1960) works in the Marshall Island. Sea urchin diet composition were based on Guieb's (1981) ~ork in a similar reef flat of Calatagan, Batangas, Southerri Luzori; Philippines. Diet proportion were adjusted based on estimated ecotrophici. effeciences so as not to exceed 1.0, but according to available knowledge on generally accepted feeding preferences. III. RESULTS AND DISCUSSION A summary of the ECOPATH,computed outputs is presented in ~ Table 2. Table 3 shows that total system throughput is 39,307 ~ g.m-Z .yr-1 with 193 g.m-2.yr":'1 (i.e. cycling index -0.5% of throughput) • Further discussions on these summary ecosystem statistics is deferred when more comparison~ can be made with other' ecosystem parameters~ , . . Figure 1, illustrates the trophic, flows involved in the Bolinao reef flat ecosystem.The arrows,have been simplified to the top two prey, if the predator food intake is < 1.0. Predators with ci higher food intake shows only prey food intake flows greater than or equal to 5. It is important to point out that though the general system output seem to be comparable to general accepted values some caveat has to be considered in some components of ttie system; This can be gleaned from the output estimates of ecotrophic efficiency (EE) values and the gross efficiericy values ~ For the predators, in general, EE values range above 0.63 to 0.98, whereas values for the damselfish (EE = 0.477) and sea urchins (EE = 0.135) are relatively low. This could possibly be attributed t6 the relatively high biomass estimates of this fish (0.729) with only a few exports or .. predator on this fish. Errors related to biomass underestimation from visual census surveys of other cryptic (moray eel) or camouflage species can, contribute to confounding the possibly nearer true values of the more conspicous fish associated to the reef benthos." The.high sea urchin estimated biomass may be real in many areas of Bolinao. On the 6therhand, much higher cstimates of exports might be present as the fisheries catch was estimated only by multiplying by 5 the recorded processed gonads sold from the area. Also, it might be possible ,that these sea urchins mayhave a relatively high episodic mortality either due to to some diseases as might be observed from many empty sea urchin tests from time to time in some areas. Also the input values for P/B; using z values assuming 2m may mot .be tenable, and thus could also cause distortions in the .Q/B values • Thc grass effecierices for the wrasses (0.586) and other piscivorous fish (0.988)·are quite,high. This again can be affected by problematic e~timation of the biomass cif these two species in the reef as they are highly mobile and mriy not be amenable to .~i~~al eensus estiiations. Also though the biomass estimations of ttie sessile invertebrate consumers (which heremay, include soft corals, sponges and tunicates) are s~eculative seem to pro~ideacceptable results~It is still not very clear how to treat the symbiotic nature cif these organisms in the entire trophic, predator-prey interaction process. ',' Overall, the ECOPATH 11 model has provided us Wl.th some insigtits into prioritizing and refinirig our estimations of the structural components (e.g~ Biomass) estimates of the Bolinao reef flat, and the functional relationships (i.e. predator-prey interactionsarid eccitrophic effeciences). This may go a lorig way in helping us iri our research thr~sts and pursuing management options for the Bolinao fisheries~ IV." ACKNOWLEDGEMENT..,.!- • , We are very gratefultoviliYChristerisen and Daniel Pauly for their enthusiastic support and motivation; arid for coming up arid making a~ailable ECOPATH 11 for use. ,We also,wish to. thank ttie Dariish International Development Agericy (DANIDA) which provided travel support for Dr. P. M. ,Alino to .present ttiis poster presentation~ Dr. H. T. Yap and Dr. E. D. Gomez provided helpful discussions relating to ttie Boliriao ecosystem dynamics. Irivaluable support was provided by so many UPMSI research assistants in going through the many unprocessed data.
'., < V~ REFERENCES Balgos, M.C. 1990. Age and growth of ,the sqtiid sepioteuthis lessoniana Lesson,1830 in Bolinao, pangasinan by statolith observation and length frequency analysis. College of science, University of the Philippines, Diliman, Quezon city. M.S.Thesis. 78 pp. Benson; A.A; and L~ Muscatine~ 1974. Wax in coral mucus: energy transfer from corals to reef fishes. Campes, W.L., J.B.P. cabarisag, A:G.C~ deI Norte; C.A. Nanola and R.B. Reyes, Jr~ 1989. stock Assessment of, the .Bolinao Reef Flat fishery yield estimates and ttie use of dominant species in assessingcoastal multispecies reseurces. 'Fisheries stock Assessment.Title XII/Collaborative Research Support Program, Working Paper Series 49, 26pp. DeI Norte, A.G.C. anci D; pauly. 1990~ virtual population estimates of monttilY recruitment and biomass of rabbitfish, siganus canaliculatus, off Bolinao" Northern Philippines. pp~ 851 854 •. In H., Hirano and I •. Hanyo (eds;). The Second Asian Fisheries Forum~ 991 p. Asian Fisheries SocietYi Manila,
Philippines. '. Fortes, M.D. 1990. seagrasses: a resouree unknowri ,in the Asean region~ Assciciation of Southeast Asian Nations/coastal Management Projeet Education Series 6, 46 pp~ Guieb, R.A. 1981; Studies on the diet and food preference of Diadema setosum Leske 1778 amd, Tripneristes gratilla Linnaeus 1758 Echinodermata: (Echinoidea) in calatagan, Batangas. Leonardo~ L.R. and C.B. Binohlan. 1986.R~production, growth, mortality and diurnal behavior of Bohadscia marmorata Jaeger. ~ (Terminal report submitted to. the Philippine Council of .. Agricultural Resources. Research and Development). (unpublished). Palomares, M.L. and D. Pauly. 1989. Multiple regression model for predicting foodconsumption of marine fish populations. Aust. J. Mar. Freshwater Res; 40:259-273
Sambilay, v. , M.L~ Palomares, S. opitz and D. Pauly, 1990. Estimates of relative food consumption by fish and invertebrate populations, required for modelling the Bolinao Reef Ecosyst~m, Ptiilippiries. Presented atUPMSljUNDP First National symposium in Marine Sci~nce, 16-18 May 1990. Bolinao. ICLARM Contribution No. 619. .-.
Table 1. Input"values using ECOPATH 11 (Christensen and Pauly, this volume) model tor the Bolinao reet f1at.
Currency of this model: 91m2
GROUP EXPORT* SIOMASS PIS aIs EE GE
1. Seagrasses 0.000 702.000 8.430 0.000 2. Seaweeds 0.988 832.000 15.340 0.000 3. Zooplankton 0.000 2.870 40.000 133.333 - 0.3 4. Sea cucumber 1.570 4.450 22.250 - 0.2 5. Sea Urchins 1.300 35.770 7.506 25.000 0.3 6. Siganus tusc. 2.760 1.820 2.214 124.000 - 7. Siganus spinus 0.800 0.710 2.214 47.920 8. Groupers (e. m.) 0.176 0.238 3.000 0.950 9. Wrasse(c.a.) 0.300 0.337 7.550 0.950 10. Moray 0.095 0.100 - 0.2 11. Damselfishes 0.100 0.729 3.300 54.700 12. Parrotfish 0.974 1.300 28.000 0.950 13. Cardinalfishes 0.325 0.405 19.390 0.950 14. Squid 0.750 3.100 16.640 0.950 15. Ot. planktiv . f. 0.006 0.084 2.730 13.650 0.2 16. 01. pisciv . f. 0.169 0.335 5.000 0.950 17. 01. herbiv. f. 0.004 0.013 2.986 14.930 0.950 18.0t.omniv.f. 0.106 0.713 30.900 0.950 19. Ses. inv. cons. 0.000 200.000 0.100 0.500 0.2 20. Ses. inv . prad . 0.000 90.000 3.200 0.000 21. Crustaceans 0.276 8.400 28.000 0.3 22. Molluscs 2.340 3.110 2.800 5.600 23. Phytoplankton 0.000 0.300 30.417 • .. -Exports- refers to -Iosses- to other 'systems and includes catches . Table 2. Output values estimated for the Bolinao reet flat using ECOPATH 11.
Currency ot this model: 91m2
GROUP EXPORT.. BIOMASS P/B alB EE
1. Seagrasses 0.000 702.000 8.430 0.000 0.068 2. Seaweeds 0.988 832.000 15.340 0.000 0.059 3. Zooplankton 0.000 2.870 40.000 133.333 0.636 4. Sea cucumber 1.570 0.371 4.450 22.250 0.950 5. Sea Urchins 1.300 35.770 7.506 25.000 0.135 6. . Siganus fuse. 2.760 1.820 2.214 124.000 0.740 7. Siganus spinus 0.800 0.710 2.214 47.920 0.723 8. Groupers (e. m.) 0.176 0.238 0.778 3.000 0.950 9. Wrasse (e.a.) 0.300 0.337 4.426 7.550 0.950 10. Moray 0.095 0.100 1.225 6.127 0.950 • 11. Damselfishes 0.100 0.729 3.300 54.700 0.477 12. Parrotfish 0.974 1.300 0.789 28.000 0.950 13. Cardinalfishes 0.325 0.405 3.039 19.390 0.950 14. Squid 0.750 0.607 3.100 16.640 0.950 15. Ot. planktiv . t. 0.006 0.084 2.730 13.650 0.950 16. OL pisciv . t. 0.169 0.335 3.942 5.000 0.950 17. OL herbiv. f. 0.004 0.013 2.986 14.930 0.919 18. Ot.omniv. t. 0.106 0.713 1.829 30.900 0.950 19. Ses. inv . cons . 0.000 200.000 0.100 0.500 0.812 20. Ses. inv . prod . 0.000 90.000 3.200 0.000 0.269 21. Crustaceans 0.276 4.981 8.400 28.000 0.950 22. Molluscs 2.340 3.110 2.800 5.600 0.822 23. Phytoplankton 0.000 0.300 30.417 0.000 0.879 24. Detritus 0.000 10.000
* -Exports- reters to -Iosses- to other systems and includes eatches. e Table 3. Summary statistics obtained from ECOPATH 11 for the Bolinao Reef Flat based data from around 1985-1989.
statistic Units Value
Sum of all production g/m2 /yr 1,938 Sum of all respiratory flows g/m2 /yr 18,965 Sum of all flows into detritus g/m2 /yr 18,405
Total System Throught g/m2 jyr 39,307
Full development capacity flowbits 86,774 Ascendency 38,799 (-44%)
• ~ 14 .-_7.8_9---- •
v~e~f~f~1~a~t~e~c~o~S~Y~8~te~m~._------th Bolinao ~ Trophic nows 0 f e __ . Fig. 1. -----