Journal of Environmental Science and Management 29-35 (Special Issue 1-2013) ISSN 0119-1144 (XWURSKLF FRQGLWLRQV GXULQJ WKH  ｿVK NLOO LQ %ROLQDR DQG $QGD 3DQJDVLQDQ 3KLOLSSLQHV 0D 7HUHVD / (VFREDU   /DUD 3DWULFLD $ 6RWWR   *LO 6 -DFLQWR 2  *DUU\ $ %HQLFR   0DULD /RXUGHV 6DQ 'LHJR0F*ORQH 2 DQG 5KRGRUD 9 $]DQ]D 2 ABSTRACT &RDVWDO ZDWHU TXDOLW\ FRQGLWLRQV LQ WKH PRQWKV SULRU WR DQG GXULQJ WKH  ｿVK NLOO RI IDUPHG PLONｿVK &KDQRV chanos) in Bolinao and Anda, Pangasinan were determined to have high total dissolved inorganic nitrogen (0.31 –  ȝ0 DQG GLVVROYHG SKRVSKDWH  ｱ  ȝ0 DORQJ WKH *XLJXLZDQHQ DQG &DTXLSXWDQ FKDQQHOV /RZ 13 UDWLRV (0.18 – 11.7) coincided with the phytoplankton blooms of Alexandrium spp. and Skeletonema costatum in May and -XQH  UHVSHFWLYHO\ The dense bloom of these two phytoplankton species for two consecutive months coupled with their die-off and decomposition depleted dissolved oxygen (<0.5 mg L -1 ) in the water column that eventually caused WKH ｿVK NLOO .H\ ZRUGV (XWURSKLFDWLRQ ｿVK NLOO INTRODUCTION (XWURSKLFDWLRQ LV WKH RYHUHQULFKPHQW RI ZDWHUV E\ QXWULHQWV WKH V\PSWRPV RI ZKLFK DUH K\SR[LD R[\JHQ GHSOHWLRQ DQG KDUPIXO DOJDO EORRPV ZKLFK GLVUXSW FRDVWDO HFRV\VWHPV 6HOPDQ HW DO  %ROLQDR DQG $QGD ORFDWHG RQ WKH ZHVWHUQ VLGH RI /LQJD\HQ *XOI LQ 3DQJDVLQDQ /X]RQ DUH H[WHQVLYH PLONｿVK Chanos chanos IDUPLQJ VLWHV Figure 1 0DULFXOWXUH DFWLYLWLHV KDYH UHVXOWHG WR WKH GHJUDGDWLRQ RI ZDWHU TXDOLW\ FRQGLWLRQV LQ WKH DUHD HVSHFLDOO\ LQ WKH *XLJXLZDQHQ DQG &DTXLSXWDQ FKDQQHOV GXH WR KLJK LQSXWV RI QXWULHQWV DQG RUJDQLF PDWWHU IURP IHHG ZDVWDJH San 'LHJR0F*ORQH HW DO  7KH DYHUDJH GHSWK RI WKH DUHD LV  P ZLWK WKH ZDWHU PRYHPHQW GRPLQDWHG PDLQO\ E\ VHPL GLXUQDO WLGHV 7KH SUHVHQFH RI ｿVK SHQV DQG FDJHV UHVWULFW WKH QDWXUDO ﾀRZ RI WKH ZDWHU WKHUHE\ DIIHFWLQJ WKH ﾀXVKLQJ UDWHV RU ZDWHU UHVLGHQFH WLPHV $ ﾀRZ UHGXFWLRQ RI   ZDV PHDVXUHG LQ DQG QHDU ｿVK FXOWXUH VWUXFWXUHV Udarbe-Walker DQG 0DJGDRQJ  )LVK NLOOV KDYH EHHQ UHSRUWHG WR RFFXU LQ WKH DUHD VLQFH  6DQ 'LHJR0F*ORQH HW DO  $]DQ]D HW DO  7KH PDMRU ｿVK NLOO LQ  WKDW LQFXUUHG DQ HVWLPDWHG ORVV RI 3K3  0 a86  0 LV DVVRFLDWHG ZLWK WKH RFFXUUHQFH RI D Prorocentrum minimum EORRP PD[LPXP FHOO GHQVLW\ RI  [   FHOOV /   :KHQ WKH EORRP GHFOLQHG WKH GHFRPSRVLWLRQ SURFHVV XWLOL]HG GLVVROYHG R[\JHQ '2 WR K\SR[LF OHYHOV KHQFH WKH FRQVHTXHQW ｿVK NLOO 6DQ 'LHJR0F*ORQH HW DO  ,Q DGGLWLRQ WR PLONｿVK LQ WKH ｿVK IDUPLQJ DUHD RWKHU PDULQH RUJDQLVPV HJ UHHI ｿVKHV HHOV VHD XUFKLQV DQG RFWRSXV DOVR SHULVKHG DQG ZHUH ZDVKHG DVKRUH $]DQ]D HW DO  ,Q -XQH  DQ HVWLPDWHG 3K3  0a86  0 ZRUWK RI PLONｿVK ZHUH ORVW WR DQRWKHU ｿVK NLOO DORQJ WKH &DTXLSXWDQ &KDQQHO LQ $QGD 3DQJDVLQDQ ZKLFK ODWHU DIIHFWHG PLONｿVK IDUPHG LQ WKH %ROLQDR DUHD 9LVSHUDV  7KLV VWXG\ H[DPLQHG WKH HQYLURQPHQWDO FRQGLWLRQV DVVRFLDWHG ZLWK WKH -XQH  ｿVK NLOO HYHQW  6HQLRU 5HVHDUFK $VVLVWDQW 7KH 0DULQH 6FLHQFH ,QVWLWXWH &ROOHJH RI 6FLHQFH 8QLYHUVLW\ RI WKH 3KLOLSSLQHV 'LOLPDQ 4XH]RQ &LW\  3KLOLSSLQHV (PDLO PDWHWHVFREDU#JPDLOFRP 2 3URIHVVRU 7KH 0DULQH 6FLHQFH ,QVWLWXWH &ROOHJH RI 6FLHQFH 8QLYHUVLW\ RI WKH 3KLOLSSLQHV 'LOLPDQ 4XH]RQ &LW\  3KLOLSSLQHV Figure 1. Water sampling stations in Bolinao and Anda, Pangasinan. Stations 1 to 4 are in Tambac Bay. 6WDWLRQV  DQG  DUH LQ &DTXLSXWDQ &KDQQHO Stations 7 to 15 are located in waters near Siapar DQG 1DUUD LVODQGV QRUWK RI $QGD 6WDWLRQV  WR 20 are in the Guiguiwanen Channel located in Bolinao.