title: Effects of Fiddler Crab Burrows on Sediment Properties in the Mangrove Mudflats of Sungai Sepang, Malaysia.
abstract: In mangrove ecosystems, litter fall accumulates as refractory organic carbon on the sediment surface and creates anoxic sediment layers. Fiddler crabs, through their burrowing activity, translocate oxygen into the anoxic layers and promote aerobic respiration, iron reduction and nitrification. In this study, the effects of four species of fiddler crabs (Uca triangularis, Uca rosea, Uca forcipata and Uca paradussumieri) on organic content, water content, porosity, redox potential and solid phase iron pools of mangrove sediments were investigated. In each crab's habitat, six cores down to 30 cm depth were taken from burrowed and non-burrowed sampling plots. Redox potential and oxidized iron pools were highest in surface sediment, while porosity, water and organic content were higher in deeper sediment. Reduced iron (Fe (II)) and redox potential were significantly different between burrowed and non-burrowed plots. Crab burrows extend the oxidized surface layer down to 4 cm depth and through the oxidation effect, reduce the organic content of sediments. The effects of burrows varied between the four species based on their shore location. The oxidation effect of burrows enhance the decomposition rate and stimulate iron reduction, which are processes that are expected to play an important role in biogeochemical properties of mangrove sediments.
authors.affiliation: School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, National University of Malaysia, UKM Bangi, Selangor D.E. 43600, Malaysia. mmk00188@hotmail.com.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Mokhtari
authors.affiliation: School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, National University of Malaysia, UKM Bangi, Selangor D.E. 43600, Malaysia. magfish05@yahoo.com.|School of Fisheries and Aquaculture Sciences, Universiti Malaysia Terengganu, Kuala Terengganu, Terengganu 21030, Malaysia. magfish05@yahoo.com.
authors.forename: Mazlan
authors.initials: M
authors.lastname: Abd Ghaffar
authors.affiliation: School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, National University of Malaysia, UKM Bangi, Selangor D.E. 43600, Malaysia. giresusup@gmail.com.
authors.forename: Gires
authors.initials: G
authors.lastname: Usup
authors.affiliation: Marine Ecosystem Research Centre, Faculty of Science and Technology, National University of Malaysia, UKM Bangi, Selangor D.E. 43600, Malaysia. zdcc@ukm.edu.my.
authors.forename: Zaidi
authors.initials: Z
authors.lastname: Che Cob
keywords: Principal Component Analysis; bioturbation; multivariate analysis; organic content; sediment oxidation