REVIEW History of the biodiversity and limno-ecological studies on Lake Taal with notes on the current state of Philippine limnology Rey Donne S. Papa1*and Augustus C. Mamaril Sr.2 1 Department of Biological Sciences, Graduate School and Research Center for the Natural Sciences, University of Santo Tomas, Manila, Philippines 2 Institute of Biology, University of the Philippines, Diliman, Quezon City, Philippines cientists have studied Lake Taal for its diverse flora KEYWORDS and fauna, active volcanism and unique limnological features. In this paper, we track the development of Tropical limnology, Caldera lakes, Eutrophication, Aquaculture scientific interest based on available literature which may help determine the current needs and future INTRODUCTION Sprospects for more in-depth research. The early part of the 20th century became the starting point of limno-ecological and Philippine limnology is inconsistent and fragmentary biodiversity research in Lake Taal. Other significant researches compared to other more established branches of biology that are such as the BFAR, PCAMRD, FISHSTRAT and Akvaplan-niva being funded in the Philippines. The two subject areas usually projects have been able to compile additional information on the prioritized and which comprise the bulk of Philippine lake lake. Unfortunately, many other aspects have remained studies are: 1) aquaculture and fisheries, and 2) pollution and unstudied while some completed projects remain unpublished or eutrophication. Studies on resource utilization for food through have become “gray literature”. The lack of funding, long-term aquaculture and fisheries help provide cheaper sources of monitoring and the publication culture among local scientists nutrition for the growing Filipino population. However, the have hampered the further growth of research on the lake. This increased demand on resources by aquaculture, urbanization and scenario calls for the revival of limnology which can develop industrialization of shore ecosystems led to misuse and thus scientific knowledge on Philippine lakes. necessitated monitoring the effects of pollution and eutrophication. Limno-ecological and biodiversity studies were left out in the process. After the pioneering works of European *Corresponding author and American scientists on Philippine lakes in the 1930s and Email Address: [email protected], 1970s, very few dedicated Filipino scientists continued the study [email protected] of Philippine freshwater ecosystems. Submitted: August 12, 2010 Revised: December 9, 2010 The Philippines is home to 59-70 lakes covering Accepted: December 15, 2010 approximately 200,000 ha nationwide (Davies et al. 1990, Published: January 10, 2011 Guerrero III 2001, Mutia 2001). They are important natural Editor-in-charge: Eduardo A. Padlan resources, yet little is known about their basic features. This is Vol.4 | No.1 | 2011 Philippine Science Letters 1 true even for Lake Taal (Figure 1), home to the lowest active (1927) reported four new fish species including the freshwater volcano and the only freshwater sardinella in the world. There is sardinella, Sardinella tawilis (Harengula tawilis Herre 1927). still a need for further research and strict implementation of The only Filipino scientist to have published papers on Lake conservation strategies (Ong et al. 2002) for its flora and fauna. Taal during this period was D.V. Villadolid, who enumerated 101 fish species belonging to 32 families and the fishing gears used This paper presents available information on the limnology by the locals to catch them (Villadolid 1932a, Villadolid 1932b, and biodiversity of Lake Taal obtained from “gray literature” Villadolid 1937). The Wallacea expedition meanwhile provided cited in peer-reviewed publications and the few peer-reviewed accounts on the origin, morphometry, hydrology and biodiversity journal articles available online (11 ISI indexed biology papers of Philippine lakes (Brehm 1939, Hauer 1941, Kiefer 1939, over the past 30 years; see http://apps.isiknowledge.com). We Woltereck et al. 1941), which included first records of some review the development of limno-ecological and biodiversity species new to science such as Alona pseudoanodonta Brehm, studies from the colonial period to the present day and discuss Diaptomus insulanus Wright and its synonym D. sensibilis how much local and foreign scientists contributed to current Kiefer, D. vexillifer Brehm, Mesocyclops hyalinus Kiefer, knowledge on this ecosystem. Pseudodiaptomus brehmi Kiefer, Tropodiaptomus giganotviger Brehm, T. prasinus Brehm, and Thermocyclops wolterecki Colonial Period: the age of exploration (1500s – 1940s) Kiefer. Spanish and American explorers, missionaries and scientists were the first to document the lake with maps, e.g., Focus on fisheries and volcanism (1950s – 1970s) Murillo Velarde’s map, drawn from exploratory expeditions The granting of Philippine independence from the United since Juan de Salcedo’s expedition in 1570. These accounts States in 1946 ushered the beginning of Filipino-led researches described the lake to have salty or brackish water where sharks, in limnology, which however, resulted in only a limited number tunas, snakes and other organisms abound and where the active of publications. The volcanic eruptions between 1965 and 1976 Taal Volcano Island is found (Buñag 1934, Hargrove 1986, prompted regular monitoring of the lake’s chemical parameters Hargrove 1991). (SiO2, pH, Na:K ratio, Cl1, and SO4) by the Commission on The Americans started exploring the islands shortly after Volcanology (forerunner of the Philippine Institute of their victory over the Spanish. Pratt (1916) published a paper on Volcanology and Seismology or PHIVOLCS). Zooplankton Philippine lakes with a lengthy discussion on Lake Taal. Herre composition was updated as part of an effort to study the zooplankton of Southeast Asian lakes where several new records were documented for Lake Taal (Ueno 1966). The Bureau of Fisheries and Aquatic Resources (BFAR) conducted research from 1972 to 1975. A report on the Sardinella tawilis fisheries and a paper on a hydrological survey of the lake were published based on this study, which provided information on thermocline depth and vertical mixing of water layers (Castillo et al. 1975, Castillo and Gonzales 1976). The Local Water Utilities Administration (LWUA) then collected data from various sources (e.g., Bureau of Public Works, Weather Bureau, and Commission on Volcanology) to study the feasibility of exporting water from Lake Taal to Saudi Arabia. They also analyzed water samples from the surface and at 43 m depth in four Figure 1. Map of Lake Taal including the lake-side towns in the surrounding watershed. stations around the lake. Their report Insert map shows its location in Luzon Is. suggested that water from Lake Taal was unsuitable for irrigation of most 2 Philippine Science Letters Vol.4 | No.1 | 2011 crops because it posed a medium alkali and sodium hazard and endemic Hydrophis semperi was published in 1985 (Watt and was deemed below export standards (LWUA 1978). Theakston 1985). The book series “Guide to Philippine Flora and Fauna” contained a chapter on freshwater zooplankton Limnological surveys in a changing environment (1980s – where Mamaril Sr. added Lake Taal to the list of localities he 1990s) sampled in the most comprehensive freshwater zooplankton Food security for the rapidly increasing Filipino population survey in the country (Mamaril Sr. 1986). Ichthyological studies and the meanwhile improving technologies in breeding of include an update on the species composition of migratory and introduced continental species such as the Nile tilapia littoral fishes (Mercene and Alzona 1990, Pagulayan et al. 1997) (Oreochromis spp.) made aquaculture a highly potential business while a report published in 1991 discussed several important investment. An aquaculture pilot project in 1975 (Aypa et al. aspects on the biology of S. tawilis (Aypa et al. 1991). In 1998, a 2008) in Lake Taal led to further hydrological surveys measuring new cladoceran species (Diaphanosoma tropicum) was physical, chemical and biological parameters in the early 1980s described based on samples collected from Lake Taal to assess the potential of fish cage culture (Aquino and Nielsen (Korovchinsky 1998). Other studies on phytoplankton, 1983). This, together with other studies by BFAR and the zoobenthos and aquatic macrophyte species richness and the Southeast Asian Fisheries Development Center (SEAFDEC) biology of important fish species have also been conducted from confirmed the suitability of lakes such as Laguna de Bay, Taal, 1995 to 2001. A majority of these have been done by students Sampaloc, Buhi and Sebu for aquaculture which would become and faculty from the Institute of Biology of the University of the a lucrative business, notably in Lake Taal, by the 1990s. Philippines in Diliman (IB–UPD) where some have been published or presented (Bleher 1996, Cukingan and Pagulayan Scientific interest on Lake Taal in the 1980s born out of 1995-1996, Cukingan and Pagulayan 2001, Lopez et al. 2001, this aquaculture potential shifted to assessing the state of Pagulayan and Espiritu 2001). ecosystem health as the unregulated proliferation of fish cage culture began to take its toll. At the beginning, these researches By the 1990s the unregulated proliferation of aquaculture pointed to more ideal conditions in the lake. A project funded by prompted the government to establish regulations on lake use the Philippine Council