Negombo Estuary Research Articles

Concentrations of trace metals in Siganus javus captured in Negombo estuary, Sri Lanka: Human health risk assessment through dietary exposure

Concentrations of aluminium, cadmium, chromium, lead, nickel and zinc in muscle and liver of a marine fish in Indo-Pacific region, Siganus javus captured in Negombo estuary were evaluated and potential human health risks associated with dietary exposure were assessed. Of the six metals analyzed, zinc was the most abundant metal in both tissues. No significant differences were found between muscle and liver with respect to cadmium and lead concentrations whereas concentrations of other metals were higher in liver compared to muscle. In human health perspective, estimated target hazard quotients for cadmium and lead were greater than the threshold of one indicating potential non-cancer health risks to heavy consumers. Estimated excess cancer risk of cadmium indicate carcinogenic health risks associated with their consumption even at moderate meal frequencies. The results revealed that consumption of S. javus from the estuary needs to be limited concerning non-cancer and cancer risks to human health.

Spatial distribution and dynamics of selected mangrove forests on the east and west coasts of Sri Lanka

The climate and edaphic characteristics primarily determine the spatial distribution and dynamics of mangrove forests. The present study was initiated to determine how species composition and structural characteristics vary along with climate and substrate salinity of six mangrove forests located on the west coast, i.e., Negombo estuary, Chilaw lagoon, and Malwathu oya estuary, and east coast, i.e., Batticaloa lagoon, Uppar lagoon, and Urani lagoon. The structural parameters in terms of tree height, basal area, biomass, and density were obtained to determine the vegetation structure of mangrove forests. The current study found that although the structure of mangrove communities of the two coasts does not differ significantly (P<0.05), plant diversity in mangrove areas on the west coast is significantly higher than that of the east coast mangroves. In contrast, the biomass accumulation in west coast mangroves is relatively lower than that of east coast. Tree height was found to influence the productivity in terms of biomass increment of mangrove forests under investigation. As such, our study suggests that regional variations in salinity, temperature, and rainfall primarily serve as drivers of variation in mangrove species composition and vegetation structure of mangrove forests along the coasts of Sri Lanka.

Influence of Environmental Factors on Growth, Survival, and Heavy Metal Accumulation in Oyster, Crassostrea madrasensis (Preston, 1916) Cultivated in Negombo Estuary, Sri Lanka

The growth of marine bivalves is affected by the interactions of several environmental variables, particularly water salinity, temperature, and food supply. Influences of environmental parameters on daily weight gain (DWG), survival and heavy metal accumulation in 225 numbers of oysters, Crassostrea madrasensis (Preston, 1916), placed at five locations in the Negombo estuary, Sri Lanka, were investigated. One-way ANOVA indicated significantly higher (P < 0.05) DWGs (0.22 ± 0.01 and 0.16 ± 0.01 g.day-1) in Pitipana and Munnakaraya, where highest mean salinity (20.9 ± 0.34 ppt) and chlorophyll-a (5.41 ± 1.49 µg.L-1) were observed. Significantly lower growth rate (0.04 ± 0.02 g.day-1) recorded in Thaladuwa, where lowest salinity (13.29 ± 1.13 ppt), highest turbidity (19.26 ± 0.99 NTU) and ammoniacal nitrogen (0.368 ± 0.078 mg.L-1) were recorded. DWG showed a significant second-order polynomial relationships with chlorophyll-a (R² = 0.44, P < 0.05) and salinity (R² = 0.28, P < 0.05). Negative exponential relationships of DWG were evident with higher level of ammoniacal nitrogen (R² = 0.24, P < 0.05) and phosphate (R² = 0.25, P < 0.05). The high concentration of lead (1.883 mg.kg-1) exceeded the EU permissible limit of 1.5 mg.kg-1 (wet weight) in oysters’ tissue where urban wastewater is released to the lagoon. There appeared to be health concerns due to heavy metal accumulation in oyster tissues in polluted areas of the estuary. The findings of this study are useful for understanding the potential impacts of environmental changes on oyster resources and the long-term sustainability of oyster fisheries and aquaculture.

The Spatial Variation of <em>Mugil cephalus</em> in the Negombo Estuary in Relation to Physico-chemical Parameters

Analysis of physico - chemical parameters gives an insight to the spatial distribution of Mugil cephalus in Negombo estuary. The present study was carried out to the spatial distribution of Mugil cephalus that is governed by the physico - chemical parameters in bottom overlying surface water in Negombo estuary, Sri Lanka. Samplings at selected sites were done during one year study period from January 2017 to December 2017. During this study, fish (Mugil cephalus) and water samples were collected at Sea mouth, Duwa, Pitipana, Munnakkaraya, Dungalpitya, Dandugam Oya and Katunayake sites. Physico - chemical parameters such as the water temperature, salinity, pH, DO, electrical conductivity, BOD, COD and nutrients levels in the bottom overlying water were measured and analyzed using employing standards methods. The results revealed that salinity, pH, EC, BOD and nutrient levels were below the maximum permissible limits of the discharge industrial wastewater quality standards of the Central Environmental Authority (CEA), Sri Lanka. The COD levels were higher than the permissible threshold limits. The seasonality in the physico - chemical levels of water were observed with a peak period from May/June and October/November, which apparently coincided with the inter monsoonal periods of the island.

The dwindling community-based management strategies in the brush park fishery of a tropical estuary: Need for co-management

Importance of participatory approaches in the management of small-scale fisheries is being increasingly highlighted today throughout the world. Brush park fishery in Negombo estuary, Sri Lanka is a small-scale fishery where traditional ecological knowledge (TEK) accumulated over generations is utilized to optimize the harvests. In the present study, the institutional robustness of the community-based management system of this fishery, which is based on TEK was assessed using Ostrom's modified design principles. Results showed that the degree of community-based management is not effective in successful management of this fishery due to common pool nature. Nevertheless, there is potential for integrating some institutional design principles through intervention of centralized management authorities. As such, co-management regimes that empower local communities are needed for the sustainability this fishery.

Potential impact of predicted sea level rise on carbon sink function of mangrove ecosystems with special reference to Negombo estuary, Sri Lanka

Abstract Unique location in the land-sea interface makes mangrove ecosystems most vulnerable to the impacts of predicted sea level rise due to increasing anthropogenic CO2 emissions. Among others, carbon sink function of these tropical ecosystems that contribute to reduce rising atmospheric CO2 and temperature, could potentially be affected most. Present study was undertaken to explore the extent of impact of the predicted sea level rise for the region on total organic carbon (TOC) pools of the mangrove ecosystems in Negombo estuary located on the west coast of Sri Lanka. Extents of the coastal inundations under minimum (0.09 m) and maximum (0.88 m) sea level rise scenarios of IPCC for 2100 and an intermediate level of 0.48 m were determined with GIS tools. Estimated total capacity of organic carbon retention by these mangrove areas was 499.45 Mg C ha− 1 of which 84% (418.98 Mg C ha− 1) sequestered in the mangrove soil and 16% (80.56 Mg C ha− 1) in the vegetation. Total extent of land area potentially affected by inundation under lowest sea level rise scenario was 218.9 ha, while it was 476.2 ha under intermediate rise and 696.0 ha with the predicted maximum sea level rise. Estimated rate of loss of carbon sink function due to inundation by the sea level rise of 0.09 m is 6.30 Mg C ha− 1 y− 1 while the intermediate sea level rise indicated a loss of 9.92 Mg C ha− 1 y− 1 and under maximum sea level rise scenario, this loss further increases up to 11.32 Mg C ha− 1 y− 1. Adaptation of mangrove plants to withstand inundation and landward migration along with escalated photosynthetic rates, augmented by changing rainfall patterns and availability of nutrients may contribute to reduce the rate of loss of carbon sink function of these mangrove ecosystems. Predictions over change in carbon sequestration function of mangroves in Negombo estuary reveals that it is not only affected by oceanographic and hydrological alterations associated with sea level rise but also by anthropogenic processes, therefore the impacts are site specific in terms of distribution and magnitude.

Some Biological Aspects of Fish Species Arius jella (Day, 1877) Occurring in the Negombo Estuary

Degradation of the water quality of Negombo estuarine system due to pollution from different sources has significantly altered the species composition of fish and Arius jella (English: Blackfin sea cat fish, Sinhala: Anguluwa) which is associated with degraded water conditions has become the most prominent fish species. Present study was carried out to study some biological aspects of these species. Samples for the study were collected from Outrigger Canoe fish catches from February to December 2015, by monthly field visits. On each sampling day, 50-60% of operated Outrigger Canoes were sampled to get necessary data of A. jella. Standard length ranged between 10.0-33.0 cm and the relative growth condition of the fish population was allometrically negative with “b” value<3.0. The ratio of males to females in the population during the study period was 0.9:1.0 (X2=0.1320). Highest GSI value of female fish was shown in May and lowest GSI value was shown in September. Average fecundity of mature ovary ranged from 30-42 eggs. Mean egg diameters of stage I eggs, stage II, stage III eggs varies 0.62±0.19, 6.64±0.53 and 12.11±1.18 respectively. Parental care was observed and eggs were found in the mouths of male fish in the months of March, May, and July. These observations are important as baseline information to assess the water quality of the estuary which will be reflected through the changes of biological aspects of this pollution indicator species. Keywords: Negombo estuary, Fishery, Fish, Crustacean, Reproductive biology, Arius jella

Morphological correlates with diet of fish assemblages in brush park fisheries of tropical estuaries

Brush park fishery in Negombo estuary, Sri Lanka is a traditional fishing practice which relies on fishes attracted to artificial woody fish aggregation devices. This study investigates whether constituent species in these brush parks exhibit morphological variations in relation to their dietary habits. Fishes caught in brush parks were sampled from April 2014 to April 2016 covering rainy, intermediate and dry seasons. There were 817 specimens of 46 species belonging to 24 families. From each specimen, 17 morphological attributes were determined and diet composition of each species was analyzed in terms of relative biovolume. Trophic index of each species estimated from the proportions of dietary items and their possible trophic level in the community was significantly related to two body proportions (Maximum body height/Maximum body width and Total length/ Maximum body height) which described shape of fish. Principal component analysis of morphometric attributes and dietary habits indicated that the species in the higher trophic levels are characterized by slender, long-body shapes and those occupy lower trophic levels are predominantly laterally compressed with deep body shapes. As such, structure of coexisting species in brush parks of Negombo estuary is predominantly along the trophic dimension and is related to morphological traits of constituent species. The predictive power of ecomorphological correlates with diets of fish species other than mugilids which are attracted to brush parks, can therefore be considered as a useful tool for conducting rapid ecological assessment.

Contribution of Vegetation Structure on Carbon Assimilation Capacity of Mangrove Ecosystem: A Case Study from Negombo Estuary, Sri Lanka

Mangrove ecosystems perform number of important ecological functions and provide a wide range of services at the local or national level and provide a unique combination of both organic matter production and sequestration, which is different from other coastal ecosystems. Mangroves are extensively used to extract twigs and branches for the construction of “Brush piles”, the predominant fishing devices in the Negombo estuary, Sri Lanka, believed to have one major impact on the vegetation structure followed by the changes in primary productivity and carbon assimilation capacity of the ecosystem. Present study was conducted with an objective of quantify and relationships between the vegetation structure and Gross Primary Productivity (GPP) of disturbed and natural mangrove stands in the Negombo estuary. Vegetation structural parameters were gathered according to the standard procedures and the measurement of Photosynthetically Active Radiation (PAR) used to calculate the Leaf Area Index (LAI) followed by the GPP. Highest values of vegetation structural parameters, LAI and GPP were recorded from estuarine waterfront and decreased with landwards, which indicated more active vegetation is near by the estuarine waterfront. Comparatively, vegetation structural/structural complexity (CI) and GPP/carbon assimilation capacity were superior in undisturbed/ natural mangrove stands (31.86-36.65 Mg ha -1 y -1 ) than that was recorded in disturbed/ replanted mangrove areas (26.42-35.25 Mg ha -1 y -1 ) at Negombo estuary. Statistically significant liner relationships (P<0.01) were revealed between vegetation structural complexity and GPP (CI=.0.498 GPP +28.208); structural complexity and Leaf Area Index (CI=0.0956 LAI +5.3551).

Shedding of gill epithelia by grey mullets (Family Mugilidae) in Negombo Estuary, Sri Lanka

The grey mullets (Family: Mugilidae) have been described as plankton feeders, herbivores, omnivores, slime feeders, foul feeders, bottom feeders, etc. In general, grey mullets are known to be benthic feeders. During a comprehensive trophic ecological study of fish assemblages in brush-parks in the Negombo estuary, Sri Lanka, carried out from 2014 to 2016, a food item that was not found in the aquatic environment, such as zooplankton, phytoplankton, macrophyte or detritus, was observed in the gut contents of mugilids. In this communication, the authors report that the frequency of occurrence of these peculiar items in the gut contents were shedded gill epithelia. Even though shedded gill epithelia were not considered as a food item, they were the most common item in the stomach contents contributing to 49.9% of the mean volume of stomach contents.

Atmospheric carbon removal capacity of a mangrove ecosystem in a micro-tidal basin estuary in Sri Lanka

Characterization of the micro-tidal mangrove forests in Negombo estuary, located on the west coast of Sri Lanka, with respect to its capacity to remove atmospheric carbon and sequestration in above and below ground plant components is the objective of this study. These mangroves constitute both natural stands (e.g. Kadolkele) and woodlots planted, protected and managed by fishermen (e.g. Wedikanda) to extract twigs and branches to construct “brush parks”, a traditional method of fishing in this estuary. Both types of mangrove stands support high species richness and structural diversity, indicating planted mangrove areas have reached a semi-natural state. Allometric relationships were used to calculate biomass increment. Differences in litterfall, above and below ground biomass increment and net primary productivity (NPP) of the two types of mangrove areas were statistically insignificant, thus indicating that they are structurally and functionally comparable. Average rate of mangrove litterfall in Negombo estuary was 802 ± 25 g m−2y−1. The average above ground biomass increment was 1213 ± 95 gm−2y−1 and below ground increment was 267 ± 18 gm−2y−1, thus the average NPP of these mangroves was 2282 ± 125 g m−2y−1. NPP showed a decreasing trend from water towards land, in line with plant density and leaf area index. A statistically significant relationship was found between vegetation structure (represented by complexity index), NPP and rate of organic carbon accumulation in mangroves. Potential carbon accumulation capacity of mangroves of Negombo estuary was estimated to be approximately 12 t ha−1y−1, which is equivalent to the amount of carbon emitted as CO2 through combustion of 19,357 L of diesel or 22,212 L of gasoline in motor vehicles. Potential atmospheric carbon removal capacity of Negombo estuarine mangroves (350 ha in extent) therefore was estimated to be 4143 t y−1, which is equivalent to removal of CO2 emitted through combustion of 6,779,000 L of diesel or 7,779,000 L of gasoline within a year.

Bioaccumulation of Heavy Metals in the Selected Commercially Important Edible Fish Species Gray Mullet (Mugil cephalus) from Negombo Estuary

Consumption of fish contaminated with non essential heavy metals such as Pb, Hg and Cd metals which exceed the required limits pose a risk to human health. Bioaccumulations of heavy metals in fish depend on several factors such as increased levels of industrial pollution and domestic solid waste dumping in the estuary. Based on the pollution inputs into the estuary, it is considered that different localities within the estuary are polluted at different rates. The objectives of this study were to determine the non essential heavy metals concentration in fish tissues and assess the seasonal variations in the ecosystem. For this study, fish tissue samples were collected from nine sampling locations along the North (n =3), South (n=2), West (n=2), and East (n=2) parts of the estuary for a period of one year from January to December 2014. Fish tissue heavy metals levels were analyzed employing standard methods. Results revealed that the average concentrations (mg/kg) varied from Pb 0 to 0.15 ± 0.06, Cd 0.35 ± 0.16 to 1.04 ± 0.28 and Hg 0.0005 ± 0.0004 to 0.05 ± 0.046 mg/kg respectively. The detected levels were below the maximum permissible limits for hazardous substances in fish and fishery products for recommendation of FAO. The detected lead, mercury and cadmium contents in fish tissue were below the standard limits defined for each element Journal of Environmental Professionals Sri Lanka: 2015 Vol. 4 No. 2: 1-9

Quantitative Analysis of Water Quality and Heavy Metals in Water, Sediments, and Tissues of Grey Mullet (&lt;em&gt;Mugil cephalus&lt;/em&gt;) from the Negombo Estuary

Colombo Journal of Multi-Disciplinary Research is published by the Faculty of Graduate Studies, University of Colombo. It is a refereed publication that publishes articles, reviews and scholarly comments relating to any field of studies. The journal is a multi-Disciplinary, innovative and international in its approach. It includes theoretical and conceptual articles as well as more empirical studies covering both historical and contemporary issues/events.

Variation of avifaunal diversity in relation to land-use modifications around a tropical estuary, the Negombo estuary in Sri Lanka

We assessed variation in avifaunal diversity at some selected habitats around the Negombo estuary in Sri Lanka in relation to land-use modifications. During the study period, we observed 48 bird species of which 47 species are residents to Sri Lanka. The avian species richness, evenness, and heterogeneity were found to be the highest at undisturbed habitats. Further, these diversity measures were negatively correlated with the intensity of anthropogenic land-use activities. Total abundance of birds increased at highly disturbed habitats due to the presence of the house crow, as it is the most abundant of all birds observed at these habitats. This study highlights the need for habitat management around estuaries, giving due consideration to existing ecological theories to conserve avifaunal diversity. It also highlights the negative impacts of the house crow on diversity of other resident avian fauna in these habitats.

Effects of Mangrove Zonation and the Physicochemical Parameters of Soil on the Distribution of Macrobenthic Fauna in Kadolkele Mangrove Forest, a Tropical Mangrove Forest in Sri Lanka

The ecology of the macrobenthic fauna of the mangrove forests has received little attention compared to the mangrove flora. The present study was aimed at filling this information gap and investigated if the diversity and distribution of macrobenthic fauna at Kadolkele mangrove forest, a pristine mangrove forest situated at the Negombo estuary in Sri Lanka, are governed by the mangrove zonation and variation of physicochemical parameters of the mangrove soil. Since the aerial photographs identified three distinct mangrove zones at Kadolkele, namely, Rhizophora, Avicennia, and Lumnitzera zones, fauna were sampled and physicochemical parameters of the soil were measured in belt transects that were established at each mangrove zone. Data were collected and analyzed using appropriate field sampling techniques and statistical methods, respectively. Results revealed that the physicochemical parameters in soil varied between the three mangrove zones and that the distribution of benthic fauna followed the mangrove zonation. Further, the diversity measures of epifauna were found to be higher than those of the infauna of this tropical estuary.

The spatial variation of macrobenthic community in the Negombo estuary in relation to physico-chemical parameters

Analysis of physico-chemical parameters gives an insight to the the spatial distribution of benthic communities in estuaries. With this view the present study was carried out to see whether the spatial distribution of macrobenthic fauna is governed by the physico-chemical parameters in sediment and overlying water in Negombo estuary, Sri Lanka. This study also attempted to determine the key physico-chemical determinants that govern this spatial distribution. During the study, the macrobenthic fauna at Moya, Virisiyanu Duwa, Kadol Kele, Dungalpitya, and Pamunugama within the estuary were collected and their species diversity and species richness were determined. Physico-chemical parameters such as the pore water salinity, temperature, pH, sand %, silt %, clay % and OM % in sediment as well as the salinity, pH, temperature, conductivity, DO, BOD5 and NO3- concentration in the over lying water were measured and analyzed using appropriate standard techniques. Results revealed that the species richness, species diversity, structure of the macrobenthic community and the physico-chemical parameters in sediment and the over lying water and the varied significantly between the five study sites. However, the species diversity and the species richness were positively correlated with the salinity and sand % while they were negatively correlated with the BOD5, silt % and OM % in the sediment and overlying water. It is therefore evident that the spatial distribution of macrobenthic fauna in Negombo estuary is governed by a combination of some key physico-chemical parameters such as salinity, sand %, OM % and BOD5 in the sediment and over lying water in this tropical estuary. DOI: http://dx.doi.org/10.4038/sljas.v16i0.6714 Sri Lanka J. Aquat. Sci. 16 (2011): 41-62

Vegetative propagation of some selected mangrove species from Negombo estuary, Sri Lanka

Mangrove forests are degraded and threatened worldwide, due to anthropogenic events. Mass production of planting material and successful germination of seeds are essential processes in rehabilitating these degraded mangrove forests. The present work was carried out to determine the efficacy of using propagule cuttings in mass production of plant materials and to determine the potential of using non mangrove soils to establish propagule cuttings for ornamental purposes. In addition air layering and stem cutting techniques were also tested for the mangrove propagation. Propagation of Rhizophora apiculata, by propagule cuttings, treated with root promoting hormones is feasible and it was possible to produce three saplings from one propagule. Indole Butyric Acid (IBA) (1000 ppm) was the best hormone concentration for inducing roots and IBA (1500 ppm) was the best for inducing shoots from propagule cuttings of R. apiculata. Air layering and stem cutting were performed with Avicennia marina and R. apiculata but none of the species was able to generate roots and therefore these vegetative propagation methods cannot be used for mass propagation of these mangrove species. Optimum growth medium and period of nursery care for mangrove saplings of R. apiculata, Ceriops tagal and Bruguiera sexangula were studied and the results revealed that best growth performance was in mangrove soils, i.e. 4.15 cm/ 4weeks for R. apiculata, 3.75 cm/ 4weeks for B. sexangula and 0.56 cm/ 4 weeks for C. tagal, while mangrove soils mixed with sand produced the second best growth for C. tagal and B. sexangula . Seedlings grown on terrestrial soils showed the lowest growth rate for all three mangrove species. However, no significant difference (P Potting media consisted only of mangrove soils as well as mangrove soils (1): sand (1), terrestrial soil alone and mangrove soil (1): terrestrial soil (1) can be used as nursery growth media for R. apiculata and C. tagal. DOI: http://dx.doi.org/10.4038/sljas.v15i0.5480 Sri Lanka J. Aquat. Sci. 15 (2010): p.25-38

Carbon Partitioning and Allometric Relationships between Stem Diameter and Total Organic Carbon (TOC) in Plant Components of &lt;i&gt;Bruguiera gymnorrhiza&lt;/i&gt; (L.) Lamk. and &lt;i&gt;Lumnitzera racemosa&lt;/i&gt; Willd. in a Microtidal Basin Estuary in Sri Lanka

Plants sequester carbon and this capacity depends on their net primary productivity and pattern of biomass/carbon partitioning within them which is less well studied for mangroves. Above (A) to below (B)-ground carbon ratio (A/B) of both Bruguiera gymnorrhiza (L.) Lamk. and Lumnitzera racemosa Willd. from where micro-tidal conditions prevail, Negombo estuary, Sri Lanka (7°11′42.18″ N ~ 79°50′47.50″ E) was approximately 3, and it resembles that of terrestrial plants than that of mangroves in macro-tidal coasts. Relatively low inundation frequency, duration and depth apparently promote aerial growth than root production. Wet oxidation without external heating, followed by colorimetric method was adopted to determine total organic carbon (TOC) of plant components. Except for leaves of L. racemosa , nearly half the biomass of all other components of the two species was composed of TOC. Statistically significant allometric relationships exist among TOC and dbh (diameter at breast height) of trees. As 96.5% of TOC in L. racemosa was in sequestered form (in the wood) it is superior to B. gymnorrhiza which accumulates carbon only 78.7% in sequestered form. Profuse branching of L. racemosa contributes to carbon sequestration capacity of the species.

Floral composition and vegetation structure of Nara Mangrove Reserve, Kadolkele, Sri Lanka and guidelines for conservation

This study was conducted to understand vegetation structure and floral composition to develop suitable protocols for the conservation of NARA mangrove reserve, Kadolkele which is 10 ha in extent and located on the right bank of the northern part of Negombo Estuary (7011’ N, 79050’ E). The ecological value of mangroves is the least concern of people in the surrounding area and this mangrove patch is frequently under threat due to high land demand and its high economic value. Therefore,it is essential to understand ecological and other relevant features in order to determine strategies to conserve this mangrove forest. Knowledge of the vegetation structure and plant composition of this mangrove reserve is an important prerequisite, not only to understand all the aspects of structure and function of this reserve, but also to formulate guidelines for their conservation and management.Vegetation data were collected in 100 m2 (10 m x 10 m) plots along three transects. Each transects extended inland from the shoreline. A quantitative study of the vegetation (true mangroves, mangrove associates, other trees and shrubs, seedlings and saplings) was conducted and species identified. The anthropogenic activities carried out in the area were also noted.In total, 29 mangrove species were recorded, out of which 18 were considered true mangroves. Thirty three other types of vegetation were noted. Families with highest abundance of mangroves were Rhizophoraceae, Avicenniaceae and Combretaceae with identical zonal distribution towards the inland, respectively. Lumnitzera racemosa andAvicennia marina were most prominent among the families of Combretaceae and Avicenniaceae, respectively. Rhizophora apiculata and R. mucronata were the most abundant in family Rhizophoraceae while other members included Bruguiera gymnorhiza,B. sexangula and Ceriops tagal. Mangrove associates were found towards landside with high abundance of Premna integrifolia, Derris scandens and Acanthus ilicifolius. Out of the 20 species of true mangroves along the Sri Lankan south-western coast, present study recorded 17 species and an additional species Avicennia alba, which was recently introduced to the reserve from Thailand.The results of the study indicate Kadolkele Mangrove Reserve consists of high biological diversity of mangroves and therefore it is extremely valuable as a living mangrove forest site readily accessible for education and research, being only 40 km north from Colombo. Destructive activities of the surrounding low income population, increasing of invasive alien floral species and deposition of the garbage such as polythene and plastics due to tidal activities of the lagoon were found to be the severe threats. In order to conserve this reserve, it is necessary to develop a management plan and detail studies should be carried out to improve the knowledge on the faunal diversity of mangrove reserve to provide information required to declare the mangrove reserve of Kadolkele as a conservation zone. Action should be taken to enhance the awareness of the surrounding community on mangroves to achieve sustainable conservation including utilization. The preliminary results of this study can be used as baseline data to monitor environmental change if further development activities continue at Negombo, and for comparison with other more degraded or rehabilitated habitats in western coast of Sri Lanka.

Monitoring Land Use Changes and their Impacts on the Productivity of Negombo Estuary, Sri Lanka Using Time Series Satellite Data

Monitoring Land Use Changes and their Impacts on the Productivity of Negombo Estuary, Sri Lanka Using Time Series Satellite Data