Sains Malaysiana 42(8)(2013): 1059–1064

Physiological Responses of Avicennia marina var. acutissima and Bruguiera

parviflora under Simulated Rise in Sea Level

(Respon Fisiologi Avicennia marina var. acutissima dan Bruguiera parviflora

di Bawah Simulasi Kenaikan Aras Air Laut)

M.Z. Rasheed, O. Normaniza* & M.Z. Rozainah

Institute of Biological Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia

Diserahkan: 1 November 2011/Diterima: 3 April 2013

ABSTRACT

Climate change components such as increased in atmospheric carbon dioxide (CO₂) and rising sea levels are likely to affect mangrove ecosystems. Healthy mature propagules of A. marina var. acutissima and B. Parviflora were subjected to two tidal treatments; shallow and deep; for six months. Shallow treatment mimicked the current tidal fluctuations and deep treatment simulated future tidal conditions under rise in sea level. Deep treatment decreased Amax of both species and significant two way interactions between tidal treatments and species were observed. A₄₀₀ was significantly reduced in the deep treatment in B. parviflora but not in A. marina. Carbon dioxide compensation point was not affected by the tidal treatments but varied significantly between both species. The ratio A₄₀₀/A_max was significantly lower in the shallow treatment in B. parviflora indicating higher carbon sink potential at moderate tidal flooding whereas A₄₀₀/A_max of A. marina was less variable between tidal treatments. Chlorophyll conductance was insensitive to tidal flooding but was significantly higher in B. parviflora than in A. marina. Carbon sequestration of  B. parviflora was substantially reduced in the deep treatment while the difference between tidal treatments was much less in A. marina. These results indicated that these two species responded differently under tidal flooding where A. marina was less sensitive to tidal. Thus, A. marina is better adapted to the projected climate change than B. parviflora.

Keywords: Climate change; inundation; mangroves; seedling growth; water logging

ABSTRAK

Unsur-unsur perubahan iklim seperti kenaikan karbon dioksida atmosfera dan aras air laut sememangnya mempengaruhi ekosistem hutan paya bakau. Dalam kajian ini, propagul Avicennia marina var acutissima dan Bruguiera parviflora didedahkan kepada 2 perlakuan air pasang; dalam dan cetek; selama 6 bulan. Perlakuan cetek mewakili keadaan semasa sementara perlakuan dalam mewakili keadaan kenaikan aras air laut pada masa hadapan. Perlakuan dalam mengurangkan nilai A_max untuk kedua-dua spesis. Nilai A₄₀₀ menurun dengan bererti bagi B. parviflora tetapi tidak A. marina untuk perlakuan dalam. Titik imbangan karbon dioksida tidak dipengaruhi oleh perlakuan air pasang tetapi menunujukkan perbezaan bererti antara kedua-dua spesis. Nisbah A₄₀₀/A_max adalah rendah pada perlakuan cetek B. parviflora yang menandakan potensi sinki karbon yang lebih tinggi manakala nisbah A₄₀₀/A_max bagi A. marina kurang menunujukkan variasi. Konduktans klorofil tidak sensitif terhadap air pasang namun B. parviflora menunjukkan nilai lebih tinggi berbanding A. marina. Sekuestrasi karbon B. parviflora menurun pada perlakuan dalam tetapi tidak begitu ketara pada A. marina. Kesemua keputusan menunjukkan A. marina lebih toleren terhadap kenaikan aras air laut berbanding B. parviflora.

Kata kunci: Kebanjiran; kegenangan air; paya bakau; pertumbuhan biji benih; perubahan iklim

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*Pengarang untuk surat-menyurat; email: normaniza@um.edu.my