Sustainable Ocean Resources Network

Abstract

Marine debris recognized as a worldwide threat to marine organisms, ecological processes and economies. Marine habitats are contaminated with man-made debris and represent the major categiries of marine debris by material type on a global basis. The study was conducted in two mangrove inhabited sites in Negombo Lagoon for a six months period during September 2016 to February 2017 to assess the debris cover and their impacts on mangroves. Debris cover was estimated in 10 x I0 m block which is divided into I m quadrats and 20 quadrats from the 100 m2 block were sampled in each site on monthly basis for macro debris (2.5 cm). The collected debris particles were categorised by material type. The study revealed that 9.83x1 05% of the substrate of the mangrove ecosystem is covered by debris. The Kadol kele site was covered by 18.80 +/- 1.74% n 1 20) while Mole Kadolwetiya was covered from 0.85+0.03% {n-120). The debris cover was varied significantly between two site (p-0.00) But there was neither significant difference of debris cover among months (p 0.41) nor month and site interaction俨0.24; Two-way ANOVA). Significantly higher debris cover was found in Kadol Kele than that of Mole Kadolwetiya. The composition of debris by material types showed that the packaging tens were dominated with a 40% followed by consumer tems (21% fishing items (8%) and rubber item ( 13%). The results of two-way ANOVA indicated that there are significant differences on abnormal roots, impacts to seedling density, under growth concentration and physical damages of flora at Kadol kele and Mole kadolwetiya at p-0.05. The study revealed that the mangroves in Negombo Lagoon are highly polluted with marine debris and their impacts on mangroves are recognized. Thus, it is recommended to make remedial measure to reduce the debris accumulation on mangroves to conserve these valuable coastal habitats.