Philippine Journal of Science 150 (3): 619-630, June 2021 ISSN 0031 - 7683 Date Received: 05 Oct 2020

Early Life Stages of Fishes in Lake Taal, : Assessment and Implications for Biodiversity Management and Conservation

Ma. Lourdes D. Merilles, Charmane B. Nochete, Benjie D. Tordecilla, and Maria Theresa M. Mutia*

Freshwater Fisheries Research and Development Center National Fisheries Research and Development Institute Butong, Taal, , Philippines

Lake Taal is the third largest lake in the Philippines and its fisheries provide livelihood to thousands of locals in its coastal areas. This study was conducted to recommend possible strategies and measures to conserve and protect the population of fishes, especially of the early life stages (ELS). The composition, abundance, and distribution of ELS and the environmental factors affecting these were investigated through monthly ichthyoplankton surveys and monitoring of water parameters, phytoplankton, and zooplankton abundances in 12 equidistant stations from January 2015 to December 2018. A total of 26,345 fish eggs and 9,140 fish larvae were collected, of which 88.9% of the fish larvae were morphologically identified into eight families, while the rest were unidentified. Families Terapontidae (44.5%) and Gobiidae (37.0%) numerically dominated the identified larvae catch. Distribution of the egg, yolk sac, and pre-flexion stages (ELS) significantly varied across stations. Three stations on the northern basin of the lake showed the highest fish egg abundance (731.82, 246.47, and 381.28 ind 100­­­­ m–3) while stations on the west, northwest, and eastern bay of the lake showed the highest abundance of fish larvae (153.76, 121.28, and 94.64 ind 100­­­­ m–3). The temporal distribution of ELS was highly associated with zooplankton, green algae, and salinity while spatial distribution was highly associated with the majority of the water parameters and chlorophyll a. Seasonal and annual distribution of ELS showed significant variation, which reveals possible spawning patterns of the identified fish larvae and the influence of varying environmental conditions to the distribution of ELS. Based on these, the identified possible spawning and larval foraging grounds are recommended as protected zones. Reduction of nutrient inputs to minimize changes in the lake trophic condition is also recommended.

Keywords: fish eggs, fish larvae, fish sanctuary, ichthyoplankton, spawning, water quality

INTRODUCTION alarmingly increasing number of introduced fish species. The lake has a total area of 236.9 km2, a maximum depth Lake Taal, a tropical freshwater lake that is the third of 198 km, and an average depth of 60 km (Castillo and largest and one of the deepest lakes in the Philippines, Gonzales 1976). Along the perimeter of the lake are 38 boasts of a diverse array of ichthyofauna – from a single tributary rivers some of which are spring waters in origin. endemic to a few native to several migratory and an The only drainage of the lake is the 8.2-km located at the southern portion of the lake, which *Corresponding Author: [email protected]

619 Philippine Journal of Science Merilles et al. Early Life Stages of Vol. 150 No. 3, June 2021 Fishes in Lake Taal empties into . Many studies conducted in distribution of ELS of fishes in the lake; 2) determined the lake accounted for the diversity of fish species in the the environmental factors affecting the temporal and lake (Herre 1927; Villadolid 1937; Mercene and Alzona spatial distribution of ELS of fishes; and 3) recommended 1990; Mercene 1997; Pagulayan et al. 1999; Aquilino et possible strategies and measures to conserve and protect al. 2011; Corpuz et al. 2016; Mutia et al. 2018a). Given the population of fishes especially of ELS. the diversity of fishes in the lake, biodiversity conservation and lake management are crucial, especially in the light of many anthropogenic problems that threaten its ecosystem. The current total fish production trend shows a continuous MATERIALS AND METHODS decline from 8,792 metric tons (MT) in 1992 to 882 MT in 2000 and 460 MT in 2011 (Mutia et al. 2018a). Study Area and Sampling Factors attributing to the decline include illegal fishing, Ichthyoplankton survey was conducted in Lake Taal once overfishing, pollution, and the expansion of aquaculture a month for 48 mo (from January 2015 to December activities in the lake (Mutia et al. 2018a). 2018). Figure 1 shows the geographic location of the The Lake Taal basin was declared a protected area under sampling stations. Sampling was done for 11 h from Republic Act 7586 or the National Integrated Protected 20:00H to 07:00H of the next day. Twelve (12) equidistant Areas System Act of 1992 and named as (approximately 4.45 km in between) sampling stations Protected Landscape (TVPL) by Proclamation 906 on scattered across the lake were sampled – namely, N1, N2, 16 Oct 1996 (DENR 2011). TVPL is managed by the N3, N4, N5, N6, N7, N8, N9, N10, N11, and N12. The Protected Area Management Board under the supervision sampling stations were georeferenced using a GPS receiver of the Protected Area Superintendent. A TVPL management (Garmin GPS Map 76CSX), and coordinates were used as plan was approved and serves as the blueprint for lake a reference during samplings. The coordinates and mean conservation (DENR 2011). Paramount to conservation depth for the 12 sampling stations are shown in Appendix I. and management of fishes in the lake is to determine and Ichthyoplankton. Samples were collected using a protect the fishes’ spawning and nursery grounds. plankton net (330-µm mesh size; 0.5-m diameter and 2-m Complete knowledge of the ELS of fishes is key in length), gauged with a Model 2030R standard flowmeter. understanding the ecology of fishes (Ooi and Chong A single horizontal tow was obtained by means of 10- 2011). This knowledge provides substantial scientific min (sub-surface; within upper 1 m) tows at an average information to evaluate larval recruitment and survival, speed of 1.5 knots (Smith and Richardson 1977) for each which in turn estimates the reproduction success of fish sampling station. The samples collected from the plankton populations and community structure (Chesalina et al. net were immediately preserved with ethanol (70% final 2013). The ELS of fishes includes the most vulnerable solution). In the laboratory, ichthyoplankton samples were stages and developments that are extremely influenced immediately sorted for fish larvae following the standard by environmental fluctuations and variability of their procedure for zooplankton biomass measurement and milieu. Thus, information on the environmental variables sorting (Smith and Richardson 1977) using a dissecting TM is valuable in assessing which factors significantly microscope (Nikon Binocular Microscope). The sorted influence the ELS of fishes’ distribution patterns, which fish larvae were morphologically identified up to the may provide insight into the impacts of climate change Family level using key identification guides (Moser 1996; and/or anthropogenic activities. Leis and Carson-Ewart 2004; Richards 2005; Mwaluma et al. 2014; Aya et al. 2016, 2017; Rodríguez et al. 2017). Fish species have different spawning patterns and Using a compound microscope equipped with an ocular reproductive behavior, and studies regarding the distribution micrometer, morphological characteristics such as body of their ELS are often limited. In Lake Taal, the larval length (BL), body depth (BD), and pre-anal length (PAL) distribution of the endemic and recently declared endangered were measured. The number of fish larvae was translated freshwater (Hata et al. 2018) into density (ind per 100 ­­­­m3) using the standard procedure has been reported and the information gathered were used from Smith and Richardson (1977). The volume of water to formulate current management policies for the species filtered in every tow was determined using the formula such as the establishment of a Tawilis reserve area (Mutia et derived from the flowmeter’s manual. al. 2017, 2018b). However, there have not been any similar studies conducted for other fish species in Lake Taal. (1) In this study, the distribution and abundance of the fish larvae community were determined. Specifically, where: it 1) determined the composition, abundance, and V = volume of water filtered

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Figure 1. Location Map of Lake Taal showing the designated sampling stations.

r = radius of plankton net (2) FMf = final flow meter reading FMi = initial flow meter reading RC = rotor constant (26,873) where: N = number of individuals in 1-ml sample Phytoplankton and zooplankton. Using a 20-µm mesh V1 = total volume of the plankton sample (ml) plankton net (30-cm diameter; 1-m length), phytoplankton V2 = volume of the lakewater filtered by plankton net samples were collected by vertically towing the net from within hauling depth (ml) a depth of five meters up to the surface. The collected samples were placed in a vial and fixed with Lugol’s iodine The mean abundances of each phytoplankton and (APHA 1998). Zooplankton samples were collected by zooplankton group in all the sampling stations were vertical tows (20 m below the surface) using a 64-µm mesh tracked monthly across the four years. plankton net (30 cm diameter; 1 m length). The samples Water quality and nutrients. During plankton tows in each were placed in a vial and preserved with 10% formalin station, water parameters – namely, water temperature (APHA 1998). Phytoplankton and zooplankton samples (◦C), conductivity (mS/cm), total dissolved solids (g/L), were microscopically examined under a compound salinity (ppt), dissolved oxygen (mg/L), pH, turbidity microscope. The species were identified morphologically (NTU), and chlorophyll-a (µg/L) – were measured using into the lowest taxa possible (Zafaralla 1998; Papa et a YSI 6600 V2 Multiparameter Water Quality Sonde al. 2008; Papa and Zafaralla 2011). The quantification within the upper 5 m of water surface. Records of in situ of different groups of plankton was determined using a measurement of water parameters were uploaded from Neubauer-type hemacytometer for phytoplankton and YSI Sonde to a computer and transformed into average Sedgewick-Rafter counting chamber for zooplankton readings per month. In addition, water samples were (APHA 1998). Phytoplankton and zooplankton densities collected at subsurface using a 500-ml sampling water (units L–1 for phytoplankton and individuals L–1 for bottle. The samples were brought to the laboratory and zooplankton) were determined by the equation: analyzed immediately for ammonia (ppm), nitrite (ppm), nitrate (ppm), and phosphate (ppm) using LaMotte

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SMART3 Colorimeter, and alkalinity (mg/L) and hardness Spatial and Temporal Distribution of Larvae and Eggs (mg/L) using HACH Test Kit. In terms of spatial distribution, fish larvae and eggs significantly varied across stations (p = 0.001 and p = 0.000, respectively). The mean monthly distribution Data Analysis patterns of fish larvae and fish eggs in the 12 sampling The effects of environmental variables on fish larval stations are illustrated in Figures 2 and 3, respectively. abundances by family were analyzed using the software Stations N3, N1, and N8 showed the highest summed CANOCO for Windows (version 5.0). Since DCA mean fish larvae abundance of 153.76, 121.28, and ordination showed the compositional length of the 94.64 ind 100 ­­­­ m–3, respectively, although the months environmental gradient to be 0.7 SD units long, of peak abundance in each station differed from each redundancy analysis (RDA) was employed for both other. In N1 and N3, fish larvae were abundant from spatial and temporal variations. Data were pooled by November–March while in N8, peak abundance was from stations based on abundance values. ELS abundances May–September. In terms of the spatial distribution of fish were logarithmically transformed [log (y + 1)], and the eggs, stations in the northern basin (i.e. N4, N5, and N6) samples were centered and standardized using Hellinger exhibited the highest summed mean fish egg abundance standardization prior to ordination analyses. Results (731.82, 246.47, and 381.28 ind 100­­­­ m–3, respectively). were illustrated with a tri-plot (Type II scaling-response Months of peak abundance in these stations were from variable focused) – the ELS of fishes, water parameters, February to March and November. In terms of the spatial zooplankton, and phytoplankton group abundances. distribution of the different ontogenetic stages of the larval Correlation analysis among ELS and environmental samples, the earliest life stages such as eggs, yolk-sac, variables was done using Pearson’s correlation. Analysis and pre-flexion stages showed significant differences of variance of the means of each parameter was performed across stations (p = 0.001, p = 0.001, and p = 0.000, by station, month, and year. Cluster analysis of plankton respectively). Aside from stations N4, N5, and N6, eggs abundance was performed by month and by station. were also abundant in stations N2, N10, and N11. Station These statistical analyses (analysis of variance, cluster N3 showed the highest concentration of yolk-sac stages analysis, and correlation) were performed using IBM amongst stations while stations N1, N3, and N12 had the SPSS Statistics v20.0. A geographic information system most pre-flexion stages. Flexion and post-flexion stages (GIS Noosa 3.6.0) was used to produce distribution maps showed no variation across stations (p > 0.05). of fish larvae and fish eggs in terms of abundance (density) across the lake. The monthly fish larvae and egg abundances for each year are illustrated in Appendices III and IV. Fish larval abundances showed apparent monthly variability (p = 0.007) (Appendix III). From November–March RESULTS the following year (2018), fish larvae abundance was maintained around 100 ind per 100 m3. Mean total fish Species Composition of Fish Eggs and Larvae larval abundance in 2015, 2016, 2017, and 2018 were A total of 9,140 fish larvae and 26,345 fish eggs were 29.32,76.92, 58.99, and 69.02 ind per 100 m3, respectively, sorted from 48 monthly ichthyoplankton surveys from and a significant difference was observed inter-annually the 12 stations in the lake. Out of the 9,140 fish larvae (p = 0.003). Similarly, the abundance of fish eggs showed collected, 8,127 or 88.9% were identified, represented significant variation across months (p = 0.000) (Appendix by eight families – namely, Terapontidae, Gobiidae, IV). Likewise, the highest fish egg abundance was Ambassidae, Atherinidae, , Syngnathidae, observed during the months around the first quarter and Cyprinidae, and Apogonidae (Appendix II). Terapontidae significantly correlated with fish larvae abundance (R2 (44.5%) and Gobiidae (37.0%) numerically dominated the = 0.988, p = 0.00). Mean fish eggs in 2015, 2016, 2017, fish larvae community, cumulatively making up 81.5% and 2018 were 32.53, 109.49, 238.03, and 202.82 ind per of the total larval composition. Ambassidae, Atherinidae, 100m3, respectively, and a significant difference was also and Clupeidae cumulatively made up 7.2% of the total observed among these years (p = 0.04). larval composition, and the rest (0.2%) belonged to other While only the eggs, pre-flexion and post-flexion stages families (Syngnathidae, Cyprinidae, and Apogonidae). showed significant differences among months (p = 0.000, Around 11.1% were unidentified mainly because of p = 0.017, and p = 0.008, respectively), the variability in the limited availability of morphological accounts of monthly abundance was apparent in all stages (Appendix freshwater fish larvae. Few specimens were also damaged, V). The highest percentage of eggs (Appendix Va) were rendering identification impossible. observed during the months of February in 2015 (72%), November in 2016 (63%), March in 2017 (45%), and

622 Philippine Journal of Science Merilles et al. Early Life Stages of Vol. 150 No. 3, June 2021 Fishes in Lake Taal

Figure 2. Average monthly abundances of fish larvae in 12 sampling stations in Lake Taal from 2015–2018.

November in 2018 (50%). Likewise, the concentration patterns of the six larval families were illustrated in of a high abundance of yolk sac stages (Appendix Vb) Appendix VI. Among the larval groups, Gobiidae, and flexion (Appendix Vd) revolve around the months Terapontidae, Ambassidae, and Atherinidae showed with the highest concentration of eggs. Pre-flexion stages significant differences across stations (p < 0.05). (Appendix Vc) showed consistently high abundance Ambassidae, Atherinidae, and Gobiidae (Appendices during the first quarter of 2017 (50%) and 2018 (32%), VIa, b, and d, respectively) showed significant differences and the last quarter of 2016 (37%). Post-flexion stages across months and years (p = 0.00), while Terapontidae (Appendix Ve) were most abundant during the last quarter (Appendix VIf) showed significant difference across years of 2016 (61%), January of 2017 (59%), and 2018 (42%). (p = 0.00). Relative abundances of Atherinidae during the first half of the year (January–May) in 2015, 2016, To further determine which fish taxa exhibit spawning and 2017 were highest at 89, 97, and 72%, respectively. seasonality based on the abundance of its larvae, seasonal

623 Philippine Journal of Science Merilles et al. Early Life Stages of Vol. 150 No. 3, June 2021 Fishes in Lake Taal

Figure 3. Average monthly abundances of fish eggs in 12 sampling stations in Lake Taal from 2015–2018.

Gobiidae was the least abundant during April–July, while water temperature were observed during May–June and Terapontidae showed no distinct pattern of occurrence. January–February, respectively. Summary of mean and Both Clupeidae and Syngnathidae showed distinct seasons ranges of other water parameters monitored are shown of occurrence. Clupeidae (Appendix VIc) occurred only in Appendix VII. All water parameters monitored did during March 2015, and February and November of 2017, not seem to vary across the twelve stations (p > 0.00). In while Syngnathidae (Appendix VIe) occurred during terms of monthly and annual variations, the majority of March–May of 2015, 2016, and 2018 and November– the water parameters showed significant differences. All December of 2015. water parameters except for turbidity showed monthly variability. Environmental Factors Plankton composition varied also across months but In terms of water conditions, water temperature in Lake showed no significant difference across stations (p Taal ranged from 25.8–32.1 °C with mean salinity > 0.05). Four groups comprised phytoplankton in all of 0.83 ppt. The months with the highest and lowest months and stations sampled, with Chlorophyceae (green

624 Philippine Journal of Science Merilles et al. Early Life Stages of Vol. 150 No. 3, June 2021 Fishes in Lake Taal algae) dominating most of the months (Appendix VIII). groups (except ) (p < 0.05), while no significant Cyanophyceae (blue-green algae), Bacillariophyceae differences were observed among stations (p > 0.05). (diatoms), and Dinophyceae (dinoflagellates) occurred in distinct seasons. High abundances of Chloro-, Cyano-, A cluster analysis on the abundances of the different and Bacillariophyceae comprised of several species while groups of phytoplankton and zooplankton (Appendix the notorious dinoflagellate species Ceratium furcoides X) revealed which stations and months showed similar alone caused lake-wide bloom during February–May plankton composition. Based on the chosen Euclidean 2016. Other groups also have months with the highest distance for group separation, the stations were clustered percentage composition in the phytoplankton community. into four groups, while the months were clustered into The diatoms also bloomed during January–February three. In general, the stations within each cluster were 2015 (Aulacoseira sp.), June 2015 (centric diatoms), adjacent to each other. Cluster I was composed of stations and January–February 2016 (Aulacoseira sp.). The on the northeast portion of the lake. Cluster II comprised cyanobacteria (Cyanophyceae) also showed high of stations in the open waters of the southern basin. Cluster abundance in September 2015 and July 2016 attributed to III had one station, which was in the southwest portion the abundance of the filamentous Anabaena sp. within the fish cage zone, while two stations in Cluster IV were stations nearshore, located near areas with lush Four major groups also comprised the zooplankton aquatic macrophyte growth. community. (Copepoda) almost always dominated the zooplankton. Nauplius larvae (Copepoda) An RDA model of the environmental factors and larval and water fleas () almost always occurred abundances among the 12 stations showed that the concurrently while rotifers occurred at different times combined effect of the first three axes accounted for (Appendix IX). Water fleas and rotifers had higher 90.41% of the total variance of data. An overall test of diversity in terms of the number of species than copepods, significance showed that the relationship between the which often lead to higher abundance. At least 20 environmental factors and larval abundances was not species of rotifers and nine species of water fleas were significant (p = 1). The RDA triplot (Figure 4) showed recorded while only two to three species are recorded in the spatial variations in egg and larval composition and copepods. Inter-annual variations and monthly differences environmental variables. The larval composition showed were significant in all phytoplankton and zooplankton to have a close association with the majority of the water

Figure 4. RDA tri-plot of spatial variations in egg and larval composition (blue arrows) and environmental variables (red arrows).

625 Philippine Journal of Science Merilles et al. Early Life Stages of Vol. 150 No. 3, June 2021 Fishes in Lake Taal parameters and chlorophyll-a in the eastern and western and costly. In this study, fish larvae were identified only basins of the lake (N3 and N8). Figure 5 shows the RDA up to the Family level since species misidentification plot for temporal variation in egg and larval composition is high in morphological identification alone (Leis and and environmental variables. The larval composition Carson-Ewart 2004). Nevertheless, several similar studies showed to have a close association with zooplankton, relying on morphological approaches alone for larval fish green algae, and salinity in the months of February, March, identification (Teixeira et al. 2019; Cajado et al. 2020) November, and December. have been able to reveal interesting patterns. The numerically dominant families of larvae identified in this study – namely, Terapontidae and Gobiidae – DISCUSSION showed significant differences in abundances across stations amongst all the larval fish identified. A previous This study is the first to document the abundance and study identified only two species of Terapontidae in the distribution patterns of ELS in Lake Taal. Despite the lake, i.e. Leiopotherapon plumbeus and Terapon jarbua increasing number of studies on the distribution of fish (Mutia et al. 2018b), while species of Gobiidae are more eggs and larvae (Ziober et al. 2012; Tobias et al. 2017; diverse in the lake, consisting of at least 20 species Zacardi et al. 2020), larval fish identification keys for (Froese and Pauly 2019). Likewise, the distribution of freshwater fishes remains inadequate (Reynalte-Tataje eggs and yolk-sac stages across stations in this study et al. 2020). Since there is limited literature available on showed significant differences, indicating the possible freshwater larval fish identification, many unidentifiable spawning grounds of Terapontidae and Gobiidae. Station specimens were encountered – around 11% of total larval N4 on the northern basin had the highest egg density than fish catch. Although identification of fish larvae through other stations and the most frequent occurrence of egg DNA barcoding has increasingly gaining popularity and in all sampling periods. However, fish larvae were not is considered an easy way to aid in identification (Ko et abundant in the area. Station N4 is located within open al. 2013; Leis 2014; Frantine-Silva et al. 2015; Almeida et waters and is frequently exposed to larger waves and al. 2018; Chu et al. 2019), the method is time-consuming strong current (as experienced during sampling). Data

Figure 5. RDA tri-plot of temporal variations in egg and larval composition (blue arrows) and environmental variables (red arrows).

626 Philippine Journal of Science Merilles et al. Early Life Stages of Vol. 150 No. 3, June 2021 Fishes in Lake Taal obtained from the Philippine Atmospheric, Geophysical, possible spawning season. For Ambassids or glassfishes, and Astronomical Services Administration showed that i.e. locally known as ning-ning in the lake, possible the dominant wind direction from September–May is spawning occurred from January to May, August, northeast, while from June–August it is southwest. In this November, and December. For Atherinidae or silversides, case, the pelagic eggs of fishes spawning in the area may i.e. locally known as guno, spawning occurred year-round have been advected to nearby areas depending on wind but with a varying peak season during January–May and direction, which resulted in the hatching site different September–November. Clupeidae or S. tawilis spawned from the spawning site. Nearby station N3, located south during February, April, and December while Syngnathidae of station N4, showed frequently abundant fish larvae. or pipefish spawned during March–May and November– In certain instances, most fish larvae were in the yolk December. The evident seasonality of fish eggs and sac stage. This station had the calmest waters among all yolk-sac stages may indicate that there were specific stations since it is located in between two landmasses spawning months of certain fish species. The presence (Volcano Island and mainland), thereby serving as a and abundance of pre-flexion stages in every sampling refuge from large waves and strong currents. The area month indicated that, in general, spawning of fishes in the was previously marked as a fish sanctuary. However, lake takes place all year round. Flexion and post-flexion due to the proliferation of fish cages in the 1980s–1990s stages showed intermittent distribution during January– specifically in this area, it was established as a fish cage June and September–December. Considering the age zone (DENR 2011). It has the highest number of fish cages and swimming ability of post-flexion larvae, their spatial among the other designated fish cage zones in the lake. distribution might be more useful in terms of determining Another station, which showed a frequently high number their foraging grounds. of yolk-sac larvae, was the station on the eastern bay of the lake (N8), wherein the area is a cove that shelters it Based on RDA, the temporal variations in the distribution from large waves. This station is located at the outskirts of overall larvae, egg, preflexion, and flexion larval stages of a lush aquatic macrophyte bed area along the coastline were highly associated with overall zooplankton and of Sala, Balete where larvae of S. tawilis were observed green algae abundance, and salinity. This implied the high (Mutia et al. 2018). All the water parameters – except dependence of ELS to the availability of food resources dissolved oxygen, phytoplankton abundances, and the such as zooplankton and green algae. Fish larvae have different zooplankton groups – showed no variability been known to feed selectively based on specific prey across stations. Zooplankton serves as prey for fish larvae characteristics (Govoni et al 1986; Munk 1997). And as and the availability of larval food is crucial to the survival ontogenetic development progresses, changes in prey of the ELS. In the zooplanktivore S. tawilis, for example, selectivity can also occur (Blaxter 1986; Pankhurst 1994). there is a high preference for larger zooplankton such as The seasonality of water parameters which were mainly calanoid copepods despite the dominance of small-bodied influenced by differing weather patterns also seems to zooplankton (Papa et al. 2008). The cluster analysis of affect prey availability and composition. Water parameters plankton according to stations (Appendix X) showed that such as water temperature, pH, DO, conductivity, Cluster I, where N3 and N4 belong, had similar plankton ammonia, and total dissolved solids were highly associated composition. These stations also showed abundant fish with abundance and cyanobacteria. Analysis of larvae and eggs, respectively. In general, results of spatial patterns through RDA indicates the stations that correlation analysis (Appendix XI) showed that ELS was were possible spawning or larval foraging grounds. moderately correlated with water temperature, nitrites Stations N3 and N8 were mostly associated with total and nitrates, and alkalinity. A weak to moderate positive larvae – comprising mostly of yolk-sac, preflexion, and correlation were observed among ELS and families of post-flexion stages. Water parameters highly associated larvae to zooplankton groups. On the contrary, weak with high larval abundance based on RDA were water negative correlations were observed among ELS and temperature, turbidity, alkalinity, total dissolved solids, families of larvae to phytoplankton groups. nitrates, nitrites, chlorophyll a, and conductivity. Seasonal and interannual variation in egg and larval In terms of fisheries management, the results of this study abundances were observed. Seasonal variation indicated identified areas that can be considered spawning and larval spawning patterns of the identified fish larvae, such foraging grounds to be declared under the TVPL Unified as the case for the identified six families of larvae Rules and Regulations on Fisheries. These areas include (Appendix VI). The presence of fish larvae all year round the vicinity of stations N3, N4, N8, and N12. Designating for Families Gobiidae and Terapontidae reflects that these areas as protected zones to avoid habitat destruction spawning occurred year-round in the lake. Meanwhile, and other anthropogenic disturbances would benefit the seasonality of abundance of Families Ambassidae, the recruitment success of fish populations in the lake. Atherinidae, Clupeidae, and Syngnathidae indicate their However, N3 is located within an aquaculture zone, and

627 Philippine Journal of Science Merilles et al. Early Life Stages of Vol. 150 No. 3, June 2021 Fishes in Lake Taal designating this area as a protected or sanctuary zone may REFERENCES not be feasible. Only stations N8 and N12 are the feasible protected zones since N4 is located in the open waters. ALMEIDA FS, FRANTINE-SILVA W, LIMA SC, As protected zones, the area must not be disturbed by any GARCIA DAZ, ORSI ML. 2018. DNA barcoding fishing or human activities or at least no construction of as a useful tool for identifying non-native species any structures that may disrupt or destroy the contiguous of freshwater ichthyoplankton in the neotropics. aquatic macrophyte beds, such as in station N8. In a Hydrobiologia 817(1): 111–119. https://doi. similar study (Mutia et al. 2018), Tawilis reserve areas org/10.1007/s10750-017-3443-5 were recommended in these same areas for the protection [APHA] American Public Health Association. 1998. of spawning grounds of the endangered S. tawilis. Standard Methods for the Examination of Water and Conservation strategies should consider protecting these Wastewater. 20th ed. Gwynn Oak, MD: United Book areas since recruitment success lies heavily on the survival Press, Inc. of ELS. In addition, since prey availability is highly AQUILINO SVL, TANGO JM, FONTANILLA IKC, affected by the environmental conditions – especially PAGULAYAN RC, BASIAO ZU, ONG PS, QUILANG nutrient loads – reducing domestic pollution and other JP. 2011. DNA barcoding of the ichthyofauna of Taal sources of nutrients in the lake is crucial in maintaining Lake, Philippines. Mol Ecol Resour 11(4): 612–619. the desired water quality for the lake ecosystem (Zafaralla https://doi.org/10.1111/j.1755-0998.2011.03000.x 1993; Querijero and Mercurio 2016). The monthly and interannual variations in environmental conditions affect AYA FA, CORPUZ MNC, LARON MA, GARCIA LMB. the structure of the ELS and plankton community and, 2017. Larval and early juvenile development of silver consequently, the recruitment of fish to adult populations; therapon, Leiopotherapon plumbeus (: hence, it is imperative to minimize sources of pollution Perciformes: Terapontidae), reared in mesocosms. in the lake. Acta Ichthyol Piscat 47(4): 347–356. https://doi. org/10.3750/AIEP/02222 AYA FA, NILLASCA VSN, GARCIA LMB, TAKAGI Y. ACKNOWLEDGMENTS 2016. Embryonic and larval development of hatchery- reared silver therapon Leiopotherapon plumbeus The authors would like to acknowledge the National (Perciformes: Terapontidae). Ichthyol Res 63(1): Fisheries Research and Development Institute for financial 121–131. https://doi.org/10.1007/s10228-015-0481-8 support. Sincere appreciation also is due to the effort BLAXTER JHS. 1986. Development of sense organs and of the following persons: Myla C. Muyot, Charice M. behaviour of teleost larvae with special reference to Faminialagao, Jude B. Majam, Nereen Y. Gacu, Jessel feeding and predator avoidance. Trans Am Fish Soc 115: Y. Tuazon, Mae Anne P. Gardon, and Maria Teresa M. 98–114. doi:10.1577/1548-8659(1986)115<98:NLFC Alcazar. Special thanks to Apolinario Deocampo, Michael DO>2.0.CO;2 de Sagun, Oscar de Sagun, Randy Tiaga, and Manuel Matienzo for providing the authors secure and safe service CAJADO RA, OLIVEIRA LS, SUZUKI MAL, ZACARDI every sampling. DM. 2020. Spatial diversity of ichthyoplankton in the lower stretch of the Amazon River, Pará, Brazil. Acta Ichthyol Piscat 50(2): 127–137. https://doi. org/10.3750/AIEP/02786 CONFLICTS OF INTEREST CASTILLO B, GONZALES C. 1976. Hydrology of Taal The authors report no conflicts of interest. The authors Lake. Fish Res J Phil 1: 62–75. alone are responsible for the content and writing of this CHESALINA T, AL-KHARUSI L, AL-AISRY A, AL- article. ABRI N. 2013. Study of Diversity and Abundance of Fish Larvae in the South-western Part of the Sea of Oman in 2011–2012. J Biol Agric Healthcare 3(1): 30–43. NOTE ON APPENDICES CHU C, LOH KH, NG CC, OOI AL, KONISHI Y, The complete appendices section of the study is accessible HUANG SP, CHONG VC. 2019. Using DNA barcodes at http://philjournsci.dost.gov.ph to aid the identification of larval fishes in tropical estuarine waters (Malacca straits, Malaysia). Zool Stud 58: 1–15. https://doi.org/10.6620/ZS.2019.58-30

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CORPUZ MNC, PALLER VG V, OCAMPO PP. MERCENE EC, ALZONA AR. 1990. Survey of Migratory 2016. Diversity and distribution of freshwater fish Fishes in Pansipit River and . Philipp J Fish assemblages in Lake Taal river systems in Batangas, 63(2): 191–229. Philippines. J Environ Sci Manag 19(1): 85–95. MOSER HG. 1996. The Early Stages of Fishes in the [DENR] Department of Environment and Natural California Current Region, California Cooperative Resources. 2011. Taal Volcano Protected Landscape Oceanic Fisheries Investigations. California Management Plan 2011–2020. Protected Area Cooperative Oceanic Fisheries Investigations Atlas Management Board. Office of the Protected Area [Atlas No. 33]. Marine Life Research Program, Scripps Superintendent. Institution of Oceanography. FRANTINE-SILVA W, SOFIA SH, ORSI ML, MUNK P. 1997. Prey size spectra and prey availability of ALMEIDA FS. 2015. DNA barcoding of freshwater larval and small juvenile cod. J Fish Biol 51(Suppl sA): ichthyoplankton in the Neotropics as a tool for 340–351. doi:10.1111/j.1095-8649.1997.tb06107.x ecological monitoring. Mol Ecol Resour 15: 1226– MUTIA MT, MUYOT M, TORRES F, FAMINIALAGAO 1237. doi.org/10.1111/1755-0998.12385 C. 2018a. Status of Taal Lake Fishery Resources FROESE R, PAULY D. 2019. FishBase. World Wide with Emphasis on the Endemic Freshwater , Web electronic publication. www.fishbase.org, version Sardinella tawilis (Herre, 1927). Philipp J Fish 25(1): (12/2019). 128–135. https://doi.org/10.31398/tpjf/25.1.2017c0017 GOVONI JJ, BOEHLERT GW, WATANABE Y. 1986. MUTIA MTM, MERILLES MLD, MUYOT MC, The physiology of digestion in fish larvae. Environ TORDECILLA BD. 2018b. Abundance and distribution Biol Fishes 16(1–3): 59–77. doi:10.1007/BF00005160 of Sardinella tawilis (Herre, 1927) larvae in Lake Taal, Philippines. Philipp J Fish 25(2): 16–26. HATA H, SANTOS M, DI DARIO F, MUNROE TA, TORRES F, QUILANG JP. 2018. Sardinella tawilis MUTIA MTM, SARMIENTO KP, MUYOT MC, (errata version published in 2019). The IUCN Red List MENDIOLA MJR, TORDECILLA BD, SANTOS of Threatened Species 2018: e.T98836352A143839946. MD. 2017. Larvae identification and development http://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS. of the only freshwater sardinella, Sardinella tawilis T20010A22247615.en endemic to Taal Lake, Philippines. Philipp J Sci 146(3): 257–265. HERRE AW. 1927. Four new fishes from Lake Taal (Bombon). Philipp J Sci 34: 273–280. MWALUMA JM, KAUNDA ARARA B, STRYDOM NA. 2014. A Guide to Commonly Occurring Larval Stages KO HL, WANG YT, CHIU TS, LEE MA, LEU MY, of Fishes in Kenyan Coastal Waters. WIOMSA Book CHANG KZ, CHEN WY, SHAO KT. 2013. Evaluating Series No. 15. Retrieved from http://www.wiomsa.org/ the Accuracy of Morphological Identification of Larval Fishes by Applying DNA Barcoding. PLoS ONE 8(1): OOI AL, CHONG VC. 2011. Larval fish assemblages 3–9. https://doi.org/10.1371/journal.pone.0053451 in a tropical mangrove estuary and adjacent coastal waters: offshore-inshore flux of marine and estuarine LEIS JM. 2014. and systematics of larval species. Cont Shelf Res 31(15): 1599–1610. https:// Indo-Pacific fishes: a review of progress since 1981. doi.org/10.1016/j.csr.2011.06.016 Ichthyol Res 62(1): 9–28. https://doi.org/10.1007/ s10228-014-0426-7 PAGULAYAN RC, LOPEZ NC, MAGBANUA FS. 1999. Littoral fishes of Lake Taal. SYLVATROP Philipp For LEIS JM, CARSON-EWART BM. 2004. The larvae of Res J 7(1&2): 84–93. Indo-Pacific coastal fishes: an identification guide to marine fish larvae (Fauna Malesiana Handbooks). PANKHURST PM. 1994. Age-related changes in the Leiden, The Netherlands: Brill Publisher. visual aquity of larvae of New Zealand snapper, Pagrus auratus. J Mar Biol Assoc UK 74(2): 337–349. MERCENE EC. 1997. Freshwater Fishes of the doi:10.1017/S0025315400039370 Philippines. In: Aquatic Biology Research and Development in the Philippines (Proceedings of the PAPA RDS, PAGULAYAN RC, PAGULAYAN AEJ. First National Symposium-Workshop on Aquatic 2008. Zooplanktivory in the endemic freshwater Biology R&D; 28–29 Nov 1995; Los Baños, Laguna). sardine, Sardinella tawilis (Herre 1927) of Taal Lake, Guerrero RDI, Calpe AT, Darvin LC eds. Philippine the Philippines. Zool Stud 47(5): 535–543. Council for Aquatic and Marine Research and PAPA RDS, ZAFARALLA MT. 2011. The composition, Development, Los Baños, Philippines. p. 81–105. diversity and community dynamics of limnetic

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zooplankton in a tropical caldera lake (Lake Taal, ZIOBER SR, BIALETZKI A, MATEUS LA DE F. 2012. Philippines). Raffles Bull Zool 59(1): 2–7. Effect of abiotic variables on fish eggs and larvae distribution in headwaters of Cuiabá River, Mato QUERIJERO BL, MERCURIO AL. 2016. Water quality Grosso State, Brazil. Neotrop Ichthyol 10(1): 123–132. in aquaculture and non-aquaculture sites in Taal Lake, https://doi.org/10.1590/S1679-62252012000100012 Batangas, Philippines. J Exp Biol Agric Sci 4(1). DOI: http://dx.doi.org/10.18006/2016.4(1).109.115 REYNALTE-TATAJE DA, LOPES CA, MASSARO MV, HARTMANN PB, SULZBACHER R, SANTOS JA, BIALETZKI A. 2020. State of the art of identification of eggs and larvae of freshwater fish in Brazil. Acta Limnol Bras 32(e6). https://doi.org/10.1590/s2179- 975x5319 RICHARDS WJ. 2005. Early Stages of Atlantic Fishes. Early Stages of Atlantic Fishes. CRC Press. https://doi. org/10.1201/9780203500217 RODRÍGUEZ JM, ALEMANY F, GARCÍA A. 2017. A guide to the eggs and larvae of 100 common Western Mediterranean Sea bony fish species. Food and Agriculture Organization (FAO), Rome. Retrieved from http://www.fao.org/3/a-i7708e.pdf SMITH PE, RICHARDSON SL. 1977. Standard Techniques for Pelagic Fish Egg and Larva Surveys. FAO Fish Tech Pap 175: 100. TEIXEIRA GE, BIALETZKI A, SOARES BE, SOUZA G, CARAMASCHI ÉP. 2019. Variation in the structure of the ichthyoplankton community in the lower Paraíba do Sul River. Neotrop Ichthyol 17(4). https://doi. org/10.1590/1982-0224-20180004 TOBIAS ML, SY AGA, BORJA VM, METILLO EB, SANTOS MD, FURIO EF. 2017. Spatio-Temporal Distribution of Ichthyoplankton in Manila Bay in Relation to Oceanographic Conditions. Philipp J Fish 24(1): 83–93. https://doi.org/10.31398/ tpjf/24.1.2016A0005 VILLADOLID J. 1937. The Fisheries of Lake Taal, Pansipit River and Balayan Bay, Batangas Province, . Philipp J Sci 63(2): 191–225. ZACARDI DM, SANTOS JA DOS, DE OLIVEIRA LS, CAJADO RA, POMPEU PS. 2020. Ichthyoplankton studies as referential for the management and monitoring of fishery resources in the Brazilian Amazon Basin. Acta Limnol Bras 32(e203): 1–9. https://doi.org/10.1590/s2179-975x6619 ZAFARALLA MT. 1998. Microalgae of Taal Lake. National Academy of Science and Technology, Taguig, Philippines. ZAFARALLA M. 1993. Limnological assessment of Taal Lake [Research Project Report]. University of the Philippines Los Baños, Laguna, Philippines. 218p.

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APPENDICES

Appendix I. Sampling stations in Lake Taal with corresponding geographic coordinates and average depth. Sampling station Latitude Longitude Average depth (m) N1 N 13° 56' 06.4" E 120° 58' 08.5" 87.4 N2 N 13° 58' 29.9" E 120° 58' 02.5" 112.7 N3 N 14° 01' 00.2" E 120° 58' 11.4" 38.4 N4 N 14° 03' 21.3" E 120° 58' 05.7" 84.0 N5 N 14° 03' 19.0" E 121° 00' 30.8" 99.6 N6 N 14° 03' 18.7" E 121° 02' 53.8" 104.8 N7 N 14° 00' 52.2" E 121° 02' 53.2" 142.4 N8 N 14° 00' 53.3" E 121° 05' 16.7" 42.2 N9 N 13° 58' 28.3" E 121° 02' 50.8" 137.2 N10 N 13° 58' 30.2" E 121° 00' 28.9" 160.1 N11 N 13° 56' 00.4" E 121° 00' 28.9" 161.7 N12 N 13° 53' 40.8" E 121° 00' 28.9" 155.8

Appendix II. Percentage composition of identified larval fishes in Appendix III. Monthly variation in mean fish larvae abundances Lake Taal from 2015–2018. per year, from 2015–2018. Values are expressed as mean ± SEM (larvae per 100 m3).

Appendix IV. Monthly variation in mean fish egg abundances per year: 2015, 2016, 2017, and 2018. Values are expressed as mean ± SEM (larvae per 100 m3).

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Appendix V. Seasonal patterns of ELS of fishes in Lake Taal: A) eggs, B) yolk-sac, C) pre-flexion, D) flexion, and E) post- flexion. Based on mean abundances in each month for the three years, standardized as a percentage of summed mean abundance over 12 mo.

Appendix VI. Seasonal patterns of six larval fish families in Lake Taal: A) Ambassidae, B) Atherinidae, C) Clupeidae, D) Gobiidae, E) Syngnathidae, and F) Terapontidae. Based on mean abundances in each month for the four years, standardized as a percentage of summed mean abundance over 12 mo.

Appendix VII. Descriptive statistics and significance of water parameters in Lake Taal from 2015–2018.

a Mean± Significance Water parameter Code Unit Range standard deviation Station Month Year Water temperature WT °C 28.9 ± 1.7 25.8–32.1 ns ** * Conductivity COND mS/cm 1.7200 ± 0.0970 1.5183–1.9597 ns ** ** Total dissolved solids TDS g/L 1.08 ± 0.03 0.97–1.15 ns ** ** Salinity SAL Ppt 0.83 ± 0.02 0.76–0.89 ns ** ** Dissolved oxygen DO mg/L 7.56 ± 2.66 3.13–14.86 ** ** ** pH pH 8.51 ± 0.46 7.27–9.73 ns ** ** Turbidity TURB NTU 7.48 ± 11.02 2.6–10.12 ns ns * Chlorophyll CHL µg/L 8.16 ± 6.63 0.5–102.8 ns ** ns Ammonia NH4 Ppm 0.35 ± 0.54 0.00–6.12 ns ** ** Nitrite NO2 ppm 0.02 ± 0.02 0.00–0.14 ns ** ** Nitrate NO3 ppm 0.07 ± 0.07 0.00–0.33 ns ** ** Phosphate PO4 ppm 1.99 ± 0.69 0.25–5.04 ns ** ** Alkalinity ALK mg/L 223 ± 33 95–320 ns ** ** Total hardness TH mg/L 264 ± 40 119–551 ns ** ** ans – not significant; * – significant at p < 0.05; ** – significant at p < 0.0

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Appendix VIII. Monthly abundances of different groups of phytoplankton from 2015–2018.

Appendix IX. Monthly abundances of different groups of zooplankton from 2015–2018.

Appendix X. Cluster analysis of stations (left) and months (right) based on the abundances of phytoplankton and zooplankton groups. Vertical red dash line represents the Euclidean distance chosen for group separation, I, II, III, or IV. Stations were clustered into four: Cluster I – N2, N3, N4, N5; Cluster II – N7, N9, N11, N12; Cluster III – N1; Cluster IV – N8, N10, N6. Months clustered into three: Cluster I – October, November, December, July, September, June, August, May; Cluster II – January, March, February; Cluster III – April.

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Appendix XI. Correlation analysis of ELS with environmental variables. WT COND TDS SAL DO pH TURB CHL NH4 NO2 NO3 PO4 ALK TH Rot Nau Cop Cla ZOO Bac Gre Cya Din PHY EGG 0.1 0.3 0.0 0.1 -0.1 -0.4 -0.2 0.2 0.8 0.2 0.1 0.3 -0.1 0.2 0.1 -0.1 -0.1 0.4 0.1 0.3 -0.1 0.6 -0.2 0.1 LARV 0.5 0.3 0.2 0.2 -0.5 -0.4 0.3 0.4 -0.1 0.4 0.3 -0.6 0.6 0.2 0.3 0.0 0.0 -0.1 0.0 -0.3 0.1 -0.2 -0.1 -0.2 Yok 0.3 0.5 0.5 0.5 -0.7 -0.5 0.5 0.3 -0.1 0.7 0.6 -0.4 0.5 0.2 -0.4 -0.5 -0.4 -0.4 -0.5 -0.2 -0.1 0.0 -0.1 -0.2 PreF 0.5 0.2 0.1 0.1 -0.3 -0.3 0.2 0.4 -0.2 0.3 0.2 -0.5 0.6 0.1 0.4 0.1 0.2 0.0 0.1 -0.2 0.2 -0.2 -0.1 -0.1 Flex 0.3 -0.1 -0.2 -0.2 0.1 0.0 -0.2 0.1 -0.2 -0.2 -0.2 -0.3 0.3 0.0 0.9 0.6 0.5 0.4 0.6 -0.1 0.1 -0.1 -0.1 -0.1 PosF -0.5 -0.5 -0.4 -0.5 0.0 0.4 -0.3 -0.1 -0.2 -0.2 0.3 0.0 -0.5 -0.1 -0.4 -0.3 0.2 0.0 -0.1 -0.2 -0.1 -0.1 0.6 0.2 AMB -0.7 -0.4 -0.6 -0.6 0.0 0.2 -0.4 0.1 0.1 -0.3 -0.1 -0.2 -0.3 -0.2 -0.1 -0.3 0.0 0.1 0.0 -0.4 -0.4 -0.1 0.5 0.0 APO -0.1 0.0 -0.2 -0.1 0.1 -0.1 -0.1 0.1 -0.1 0.2 0.2 0.2 -0.5 -0.4 0.1 0.2 -0.1 0.3 0.2 0.6 0.2 0.3 -0.3 0.2 ATH 0.3 -0.3 -0.4 -0.4 0.4 0.2 -0.3 0.1 -0.2 -0.4 -0.4 -0.3 0.1 0.0 0.8 0.8 0.6 0.5 0.7 -0.1 0.3 -0.3 0.0 0.0 TER 0.5 0.2 0.0 0.1 -0.3 -0.3 0.2 0.4 -0.1 0.2 0.1 -0.6 0.6 0.1 0.6 0.2 0.2 0.1 0.3 -0.2 0.1 -0.1 -0.2 -0.2 CLU -0.4 -0.2 -0.2 -0.1 0.2 0.1 -0.1 -0.5 0.0 -0.3 -0.7 -0.1 -0.4 -0.2 0.0 0.3 0.2 0.2 0.2 0.0 -0.4 -0.5 0.0 -0.2 CYP 0.3 -0.1 -0.2 -0.2 0.2 0.1 -0.1 0.1 -0.2 -0.3 -0.3 -0.3 0.2 0.0 0.9 0.6 0.5 0.4 0.6 -0.1 0.1 -0.1 0.0 -0.1 GOB 0.5 0.5 0.5 0.4 -0.7 -0.6 0.3 0.4 0.2 0.7 0.7 -0.4 0.6 0.3 -0.1 -0.4 -0.3 -0.2 -0.3 0.0 -0.1 0.2 -0.3 -0.2 SYN -0.3 -0.3 -0.4 -0.4 0.0 0.3 0.0 0.2 -0.2 -0.2 0.3 0.0 0.1 -0.3 -0.3 -0.4 0.1 -0.3 -0.2 -0.3 0.2 0.0 0.6 0.4 Note: EGG – total eggs, LARV – total larvae, Yok – yolk sac, PreF – preflexion, Flex – flexion, PosF – post flexion, AMB – Ambassidae, APO – Apogonidae, ATH – Atherinidae, TER – Terapontidae, CLU – Clupeidae, CYP – Cyprinidae, GOB – Gobiidae, SYN – Syngnathidae, WT – water temperature, CON – conductivity, TDS – total dissolved solids, SAL – salinity, DO – dissolved oxygen, pH – pH, TUR – turbidity, CHL – chlorophyll, NH4 – ammonia, NO2 – nitrite, NO3 – nitrate, PO4 – phosphate, ALK – alkalinity, TH – total hardness, Rot – , Nau – nauplii, Cop – copepod, Cla – cladocera, ZOOP – overall zooplankton, Bac – diatoms, Gre – green algae, Cya – cyanobacteria, Din – dinoflagellates, PHYT – overall phytoplankton Merilles et al . EarlyLifeStagesof Fishes inLake Taal