LAKE BUHI

A view on the lakeshore

Photo.
Photo: R. N. Tagaarino


A. LOCATION

  • Camarines Sur, the Philippines.

  • 13:05N, 123:05E.


B. DESCRIPTION

    Lake Buhi is a unique tropical lake serving as home of the world's smallest commercial fish The lake provides for many uses such as fishery, navigation, water reservoir for irrigation, hydroelectric power and domestic water supply. This 1,800 hectare freshwater lake sits in the valley between two ancient volcanos, Mt. Malimas and Mt. Iriga. The lake was formed in 1641 when a strong earthquake caused the side of Mt. Iriga to collapse, forming a natural dam on small streams (Q).

C. PHYSICAL DIMENSIONS (1)

    Surface area [km2] 15-18
    Maximum depth [m] 18.2
    Mean depth [m] 6.8

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL (Q)
  • Bathymetric map: Fig. ASI-20-01.

  • Names of main islands: None.

  • Number of outflowing rivers and channels (name): 1 (Tabao R.).

D2 CLIMATlC (2)
  • Climatic data at Legaspi*, 1952

    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    Mean temp. [deg C] 25.7 25.9 26.7 27.7 28.2 28.1 27.4 27.4 27.3 27.1 26.7 26.2 27.0
    Precipitation [mm] 366 265 218 158 178 194 235 209 252 313 479 503 3,370
    * Circa 50 km southeast from the lake.

    Fig. ASI-20-01
    Bathymetric map with the location of five sampling stations (Q).

  • Water temperature [deg C](Q)

    Iraya, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P*1 28.9 28.6 28.0 27.8 27.0
    A*2 27.9 28.5 28.0 27.5 26.8
    Cabatuan, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 28.3 29.3 28.2 27.8 27.0
    A 28.2 29.0 28.0 27.8 27.0
    Salvacion, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 29.2 29.9 28.9 28.1 28.0
    A 28.3 29.0 28.0 28.1 27.2
    Cruz-San Buena, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 28.8 29.3 28.9 27.5 27.5
    A 28.2 29.3 28.0 27.3 27.5
    Soboc, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 29.0 29.3 28.5 27.5 27.2
    A 28.2 28.8 28.5 27.3 26.8
    *1 Photic zone. *2 Aphotic zone (1 m below transparency).

E. LAKE WATER QUALITY

E1 TRANSPARENCY [m]
    Station I, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    4.1 3.1 3.0 3.4 2.5
    Station II, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    4.2 2.9 3.75 3.5 2.8
    Station III, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    3.8 3.8 3.60 2.8 2.7
    Station IV, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    3.3 2.9 2.8 3.6 2.6
    Station V, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    3.4 4.4 4.0 3.2 2.2
E2 pH
    Iraya, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P*1 8.15 8.1 6.9 8.1 8.5
    A*2 7.95 8.2 6.9 8.0 8.55
    *1: Photic zone. *2: Aphotic zone (1 m below transparency).
    Cabatuan, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 8.25 8.2 8.0 7.95 8.70
    A 7.8 8.4 8.1 7.90 8.70
    Salvacion, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 8.1 8.3 8.5 7.71 8.60
    A 7.9 8.3 8.85 7.78 8.61
    Crus-San Buena, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 8.3 8.7 8.7 7.85 8.5
    A 8.4 8.7 8.75 7.90 8.5
    Soboc, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    8.35 8.6 6.9 7.90 8.6
    8.5 8.6 6.9 7.95 8.65
E4 DO [mg l-1]
    Station I, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P*1 7.4 8.1 5.8 6.1 10.2
    A*2 7.3 7.2 6.0 4.5 10.0
    *1 Photic zone. *2 Aphotic zone (1 m below transparency).
    Station II, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 7.5 7.8 6.8 6.3 9.9
    A 6.7 7.7 4.4 6.1 10.0
    Station III, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 6.8 7.3 6.5 6.1 10.8
    A 6.2 6.5 4.4 6.0 10.9
    Statio IV, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 7.0 7.6 6.9 6.5 11.0
    A 6.8 7.4 6.2 6.0 10.8
    Station V, October-December 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 7.0 8.1 6.3 6.0 10.9
    A 5.8 6.0 5.2 6.1 9.2
E6 CHLOROPHYLL CONCENTRATION [micro l-1]
    Station I, 1986
    Depth [m] Oct Nov Dec
    0.0737 18.92 68.15
    Station II, 1986
    Depth [m] Oct Nov Dec
    0.0338 33.35 34.8
    Station III, 1986
    Depth [m] Oct Nov Dec
    0.2525 19.58 39.15
    Station IV, 1986
    Depth [m] Oct Nov Dec
    0.1788 21.03 21.75
    Station V, 1986
    Depth [m] Oct Nov Dec
    0.0748 6.53 30.45
E7 NITROGEN CONCENTRATION (8)
  • Total-N [mg l-1]

    Station I, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P*1 0.901 0.139 0.238 0.389 0.104
    A*2 0.454 0.104 0.401 0.421 0.300
    *1 Photic zone. *2 Aphotic zone (1 m below transparency).
    Staiton II, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 0.263 0.295 0.160 0.170 0.418
    A 0.617 0.309 0.125 0.219 0.575
    Station III, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 0.596 0.174 0.160 0.648 0.504
    A 0.440 0.054 0.182 0.673 0.590
    Station IV, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 0.362 0.054 0.104 0.381 0.410
    A 0.136 0.195 0.061 0.203 0.426
    Station V, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 0.341 0.160 0.132 0.203 0.394
    A 0.426 0.182 0.174 0.227 0.496
E8 PHOSPHORUS CONCENTRATION (Q)
  • Total-P [mg l-1]

    Station I, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P*1 0.115 0.038 0.047 0.040 0.066
    A*2 0.095 0.569 0.059 0.041 0.038
    *1 Photic zone. *2 Aphotic zone (1 m below transparency).
    Station II, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 0.094 0.077 0.050 0.088 0.042
    A 0.095 0.060 0.047 0.033 0.035
    Station III, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 0.092 0.065 0.045 0.033 0.073
    A 0.157 0.093 0.064 0.059 0.037
    Station IV, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 0.096 0.130 0.067 0.045 0.036
    A 0.221 0.123 0.060 0.069 0.038
    Station V, 1986
    Depth [m] 30 Oct 6 Nov 17 Nov 30 Nov 18 Dec
    P 0.143 0.128 0.057 0.033 0.040
    A 0.281 0.120 0.062 0.034 0.037
E10 PAST TRENDS
  • Watar temperature [deg C]

      • 1977-1978*1 May-Oct 1982*2 Nov 1982-Jul 1983*2
      28.5 27.0 29.0
      *1 (3). *2 (4).
  • Transparency [m]

      1977-1978*1 1982*2 1986-1987*3
      0.8-4.6 0.4-4.0 2.1-4.6
      *1 (3). *2 (4). *3 (Q).
  • pH

      • 1977-1978*1 May 1982-Jul 1983*2 1986-1987*3
      *1 (3). *2 (4). *3 (Q).
  • DO [mg l-1]

    1977-1978*1 May 1982-Jul 1983*2
    8.0-11.0 3.45-9.95
    *1 (3). *2 (4).
  • PO4-P [mg l-1]

      • 1977-1978*1 May-Dec 1982*2 Jun-Jul 1983*2
      0.07 0.201 0.407
    *1 (3). *2 (4).

F. BIOLOGICAL FEATURES

F1 FLORA (Q)
  • Floating macrophytes: Eichhornia crassipes.

  • Submerged macrophytes: Hydrilla sp., Vallisneria sp.

  • Phytoplankton

    • Microcystis aeruginosa (perennially dominant and widely distributed).
F2 FAUNA
  • Zooplankton: Protozoa, Arthropoda, Trochethninthes sp. (5).

  • Benthos: Oligochaetes, Chironomus sp. (5).

  • Fish: Tilapia nilotica*, mudfish, catfish (Q).

    • * Economically important.
F4 BIOMASS (Q)
  • Total phytoplankton [g m-3]

    1986
    Station Oct Nov Dec
    I 19.3 8.95 14.0
    II 15.9 5.65 11.2
    III 17.8 7.0 8.2
    IV 14.2 8.3 14.2
    V 14.8 10.6 14.0
F5 FISHERY PRODUCTS
  • Aunual fish catch [kg](6, 8)
    1983: 55,169.
  • Fishery products other than fish (Q)
    Shrimps and bivalves.
F7 NOTES ON THE REMARKABLE CHANGES OF BIOTA IN THE LAKE IN RECENT YEARS
    Decline in species diversity and fish yield (7, 8). Loss of migratory species (Q).

G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA (7)
    1980
    Area [km2] [%]
    Natural landscape
    - Woody vegetation
    Primary forest 2,050 19.1
    Secondary forest 2.180 20.3
    Herbaceous vegetation
    - Active "kaingin" 1,070 10.0
    Grassland 710 6.6
    Agricultural land
    - Crop field
    Rice land 1,807 16.8
    Coconut plantation 2,380 22.1
    Bare areas 555 5.2
    Total 10,752 100
  • Main types of woody vegetation
    Primary and secondary forest, coconut plantation.
  • Main kinds of crops
    Rice, maize, sweet potato, cassava, abaca. Cropping systems: 1) relay system, 2) intercropping, 3) slash and burn farming (locally called "kaingin").
  • Levels of fertilizer application on crop fields: Light.

  • Trends of change in land use in recent years
    Primary forest lands have diminished and being replaced by secondary forests. Annual crops such as rice and maize and perennial crops (coconut and coffee) are being planted in alienable and disposable lands. Shifting cultivation and illegal logging have become notable.
G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE (Q)
    No. of persons engaged Main products or major industries
    Primary industry
    - Fisheries 2,136 Tilapia nilotica, Ophicephelus striatus, Cyprinus carpio, Palaemon sp. and bivalves
G3 POPULATION IN THE CATCHMENT AREA (Q)
    Population Population density [km-2] Major cities (population)
    Rural 48,265 441 None

H. LAKE UTILIZATION

H1 LAKE UTILIZATION (Q)
    Source of water and navigation.

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS (Q)

I1 ENHANCED SILTATION
  • Extent of damage: Not serious.

I3 EUTROPHICATION
  • Nuisance caused by eutrophication
    Unusual algal bloom: Microcystis sp.
I4 ACIDIFICATION
  • Extent of damage: None.


L. DEVELOPMENT PLANS (Q)

Hydraulic control structure in operation since 1984.

M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES (Q)
  1. Program on Environmental Science and Management (PESAM)
  2. University of the Philippines at Los Baffos (UPLB)

N. SOURCES OF DATA

  1. Questionnaire filled by Dr. Marlito Lanzona Cardinas, Institute of Chemistry, University of the Philippines at Los Baiios and by Dr. Rogelto N. Tagarino, Institute of Environmental Science and Management, University of the Philippines at Los Bailos.
  2. PCARRD (1981) State of the Art. Lakes and Reservoirs Research, Fisheries Series No. 1. PCARRD, Los Bailos, Laguna, the Philippines.
  3. Flores, J. F. & Balagot, V. F. (1969) Climate of the Philippines. "World Survey of Climatology Volume 8, Climates of Northern and Eastern Asia" (ed. Arakawa, H.), pp. 177-181, Elsevier Scientific Publishing Company. Amsterdam- London-New York.
  4. BRBDP (1982) Annual Report. Bicol River Basin Development Program, Buhi Camarines Sur.
  5. Zafaralla, M. T., Cadiz, N. M., Magcale, D. B., Vidal, L. R. & Auila, L. (1986) Studies on the Phytoplankton of Lakes in Camarines Sur, the Philippines. I. Dynamics of Water Quality in Buhi in Relation to Changes in Community Structure and Primary Production. Occasional Paper No. 5. PESAM, UPLB, College, Laguna, the Philippines.
  6. Olatio, V. L. & Clemente, E. P. (1983) Annual Report of the Resource Assessment of Lake Buhi for 1983. Bureau of Fisheries and Aquatic Resources, Region V, Bicol Region, Philippines.
  7. Conway, G. R. & Sajise, P. E. (ed.)(1984) The Agroecosystems of Buhi: Problems and Opportunities, Program of Environmental Science and Management (PESAM) and BRBDP.
  8. Tagarino, R. N. et al. (1985) An Economic Analysis of Capture Fishery Activities in Lake Bato and Lake Buhi. Terminal Report, UPLB-PCARRD Proj. #89-320-9. UPLB, College, Laguna, the Philippines.
  9. Fisheries Statistics (1980) Bureau of Fisheries and Aquatic Resources (BFAR), Quezon City, the Philippines.