Distribution and Contamination of Arsenic in Fish, Gastropods and Bivalves in the Aby and Tendo Lagoons in East of Ivory Coast

Lagoons are ecosystems for biodiversity and the livelihoods of coastal communities. The main objective of the study was to analyze the variability of arsenic concentrations in gastropods and bivalves in the Aby and Tendo lagoons, taking into account spatial, seasonal and hydrological variations. The study was carried out in four stages spread over two successive hydroclimatic cycles, including two seasons during the rainy season and two more during the dry season. The samples were taken in two areas of the Aby and Tendo lagoons. Arsenic levels were measured by ICP-MS. The results showed that mean arsenic concentrations in the muscles of organisms in Aby Lagoon ranged from 0.01 to 1.26 μg As/g, with a mean and median of 0.17 and 0.06 μg As/g, respectively. Fish had the highest levels of arsenic, followed by crustaceans, while molluscs and plants had lower and comparable concentrations of As. Arsenic concentrations in tilapia and jawbones varied significantly between sites and seasons, with higher concentrations at Tendo and during the rainy season. Arsenic concentrations in gastropods and bivalves were significantly higher than those of other species, with averages of 0.74 and 1.03 mg As/kg, respectively.

Assessment of Selenium Contamination in Sediments of the Aby and Tendo Lagoons in Côte d’Ivoire

Selenium is a trace element that can have both beneficial and harmful effects on aquatic life. The Aby Lagoon is a coastal environment in Côte d’Ivoire that receives selenium inputs from various natural and anthropogenic sources. The aim of this study was to assess the levels of selenium in the sediments of the Aby Lagoon and its tributaries, the Tanoe River and the Tendo Lagoon, and to examine the spatial and seasonal variations of selenium concentrations. Sediment samples were collected from different sites and seasons, and selenium concentrations were measured by atomic fluorescence spectrometry. The results showed that the average concentration of selenium in the sediments of the Aby Lagoon was 0.82 mg/kg, indicating moderate contamination. The concentration of selenium varied between sites and seasons, with higher values in the channel of the Tendo Lagoon and during the dry season. The study highlighted the complexity of selenium dynamics in aquatic ecosystems, and the need to take into account seasonal and spatial variability as well as interactions between environmental factors. The study also suggested potential ecotoxicological risks for some sensitive organisms in certain areas of the lagoon. This study contributes to the knowledge of the dynamics of selenium in lagoon ecosystems and to the assessment of the environmental risks associated with its presence.

Use of piezocone tests to predict consolidation yield stress and overconsolidation ratio of lagoonal deposit soil

Existing empirical methods for interpreting the consolidation yield stress and the overconsolidation ratio （OCR） in clays from piezocone tests are briefly reviewed. It can be seen that no universal correlation exists for all worldwide sites. However, for a given clay deposit, there does exist a most appropriate method to reflect the consolidation yield stress and the OCR based on piezocone test data. Three empirical methods are compared based on the piezocone test data collected on Lixia River lagoonal deposit soil sites in the north of Jiangsu province. The objective of this study is to evaluate the validity of the existing relationships linking the consolidation yield stress to piezocone test data and identify the appropriate method for Lixia River lagoonal deposit soil. It is shown that the correlation based on the net tip resistance has much higher accuracy for estimating the consolidation yield stress of lagoonal deposit soil than other methods.

Structure of the Community of Dominant Fish Species Associated to Soft-Bottoms in the Lagoon of La Paz, B.C.S., México

The study of fish communities from coastal lagoons allows a better understanding of role of these organisms in these systems, and the effect of anthropogenic impact. The aim of the present study was to determine the community structure, in particular dominance of fish species associated to soft bottoms in the lagoon of La Paz. Six bimonthly samplings were carried out in seven localities from November 2016 to September 2017 and physicochemical parameters were recorded. Analysis of temperature showed differences between two marked seasons, warm and cold. Species richness showed differences between months and localities. Shannon-Weaver index and Pielou’s evenness showed significant differences only between months. Simpson’s index suggests a high diversity. According to the BVI, 15 species from the families Haemulidae, Sciaenidae and Gerreidae, were the most biologically important. Zoogeographic affinity analysis showed that 58% of the species prefer the Province of Cortez. Dominant species recorded in this study play a key role in soft-bottom systems like the lagoon of La Paz.

Assessing Future Flooding Risk in a Coastal Lagoon Using Hydrogeological Approaches and Analysis of the 2021 Flood Event: A Case Study of Tasi-Tolu Lagoon, Dili, Timor-Leste

This study aims to apply a hydrogeological approaches and analysis of the 2021 flood event of Tasi-Tolu Lagoon to achieve four specific goals. Firstly, the study seeks to determine the natural characteristics of the lagoon, which include factors such as size, depth, water quality, and ecosystem composition. Secondly, the influence of precipitation on the water volume in the lagoon will be examined. This analysis involves assessing historical rainfall patterns in the region, as well as the amount and frequency of precipitation during the 2021 flood event. Thirdly, the hydrogeologic and geologic conditions of the lagoon will be evaluated. This involves examining factors such as the type and structure of the soil and bedrock, the presence of aquifers or other underground water sources, and the movement of water through the surrounding landscape. Finally, the study seeks to assess the risk of future flooding in Tasi-Tolu Lagoon, based on the insights gained from the previous analyses. Overall, this study’s goal is to provide a comprehensive understanding of the hydrogeological factors that contribute to flooding in Tasi-Tolu Lagoon. This knowledge could be used to inform flood mitigation strategies or to improve our ability to predict and respond to future flooding events in the region.

Hydro-Sedimentary Dynamics of the Grand-Popo Lagoon Located Upstream of the Mobile Embouchure “Bouche du Roy” in South-Western Benin

The problems of flooding, bank erosion and even the breaching of the barrier beach by the Grand-Popo lagoon are a concern in the south-western Beninese river-lagoon complex. The present study aims to improve the knowledge of the factors controlling the hydro-sedimentary functioning of this lagoon of Grand-Popo. It was based on bathymetric and sedimentological studies and the analysis of physical-chemical parameters of the water and allowed to know the morphology of the lagoon bottom and the distribution of sedimentary facies according to the intensity of the water current. The salinity of the lagoon waters shows a west-east gradient passing thus from 0‰ to 0.78‰ in the main direction of flow. Over the whole lagoon system, the average liquid flows vary from -38.499 to 159.13 m3/s. The bathymetry indicates depths varying from 0.4 to 6.5 m, revealing type V and type U lagoon bottoms which reflect acute bottom concavities marked by hollowing under the effect of strong currents or by sandy terraces resulting from the continuous input of sediments carried by the Mono River. These sediments are heterogeneously distributed in the lagoon bottom and vary from free sand to mud. Given the complexity of the factors that control the hydro-sedimentary functioning of the Grand-Popo lagoon, it is recommended that periodic hydrological and bathymetric monitoring be carried out to locate exceptional variations in water levels to prevent not only the risks of overflowing lagoon waters and the flooding that follows but also spectacular erosion of the lagoon banks.

Factors regulating population dynamics of the amphipod Ampithoe valida in a eutrophic subtropical coastal lagoon

Year-round investigations were carried out to address the population dynamics of amphipod Ampithoe val- ida and its potential regulating factors in the Yundang Lagoon （a eutrophic subtropical coastal lagoon in Xiamen City, China） from October 2007 to October 2008. The results show that A. valida population was largely composed of juveniles and reached a peak abundance （12.02× 10^3 ind./m2） in March, but sharply shrunk in July. The monthly variation pattern ofA. valida seemed to follow that of Ulva lactuca which is the main food resource for A. valida, indicating a strong influence of food availability on A. valida popu- lation dynamics. Life cycle studies in laboratory indicate that A. valida adopted an r-selected life strategy, e.g., rapid growth rate （0.216-0.302 mm/d）, consecutive breeding （4-10 times）, short reproductive rhythm （9-17 d） and huge fecundity （24-192 eggs or 6-94 juveniles per brood）, which contributed to the fast pop- ulation growth ofA. valida from January to March. Although temperature may also be a significant cause, A. valida could grow quickly and show normal reproductive traits （i.e., the timing of sexual differentiation or maturity, the reproductive rhythm, the number of broods all through its lifespan and offspring produc- tion） in temperature between 15-30~ C. Therefore, the temperature variation in the lagoon water should not account for the sharp variation of A. valida population by affecting the survival, growth and reproduction of the amphipod. However, negative correlation between water temperature and U. lactuca biomass in the lagoon suggested that temperature could have indirectly affected the population dynamics ofA. ualida by affecting its food availability. The authors conclude that, in the Yundang Lagoon, the population dynamics ofA. validawas mainly controlled by the food availability rather than water temperature.

Spatial and temporal variations of sedimented organic matter in Xiaohai Lagoon,Hainan Island

The characteristics of grain-size,total organic carbon (TOC) and total nitrogen (TN) contents,TOC/TN ratios,stable carbon isotope (δ13C) and 210Pb dating were measured in six sediment cores from the Xiaohai Lagoon.The results show distinct spatial and temporal variations in sedimentation patterns.The sediments are dominated by clayey silt,sandy silt and by silty sand in the southern,middle lagoon and the northern lagoon,respectively.TOC and TN contents decline from south to north.Sedimentation rates,determined by 210Pb dating,tend to decrease from south to middle.However,the determination of sedimentation rate in the north is difficult.These spatial variations are related to the variations in sediment sources and hydrodynamic conditions in the Xiaohai Lagoon.The variations of organic matter signatures can be divided into two stages in the cores from the southern and middle lagoon.Before 1988,the organic matter signatures are relatively stable.The contribution of terrestrial organic carbon sources varies between 60％ and 85％.After 1988,the organic matter signatures demonstrate significant variations.TOC and TN contents increase rapidly,TOC/TN ratios decrease,δ13C values shift to higher and the contribution of terrestrial organic carbon sources decreases to 40％-50％.The contributions of phytoplankton organic matter have increased in the sediment since 1988.Increasing aquaculture activities have had a significant impact on organic matter signatures since 1988.The sedimentation rates have increased rapidly in the southern and middle lagoon since 1988 due to the anthropogenic activities which include aquaculture,mining and deforestation.These activities have caused eutrophication and increased siltation in the southern and middle lagoon.

Classifying the sedimentary environments of the Xincun Lagoon,Hainan Island,by system cluster and principal component analyses

An understanding of the sedimentary environment in relation to its controlling factors is of great importance in coastal geomorphology,ecology,tourism and aquaculture studies.We attempt to deal with this issue,using a case study from the Xincun Lagoon,Hainan Island in southern China.For the study,surficial sediment samples were collected,together with hydrodynamic and bathymetric surveys,during August 2013.Numerical simulation was carried out to obtain high-spatial resolution tidal current data.The sediment samples were analyzed to derive mean grain size,sorting coefficient,skewness and kurtosis,together with the sand,silt and clay contents.The modern sedimentary environments were classified using system cluster and principal component analyses.Grain size analysis reveals that the sediments are characterized by extremely slightly sandy silty mud（ESSSM） and slightly silty sand（SSS）,which are distributed in the central lagoon and near-shore shallow water areas,respectively.Mean grain size varies from 0 to 8.0Ф,with an average of 4.6Ф.The silt content is the highest,i.e.,52% on average,with the average contents of sand and clay being 43% and 5%,respectively.There exists a significant correlation between mean size and water depth,suggesting that the surficial sediments become finer with increasing water depth.Cluster analyses reveals two groups of samples.The first group is characterized by mean grain size of more than 5.5Ф,whilst the second group has mean grain size of below 3.5Ф.Further,these groups also have different correlations between mean grain size and the other grain size parameters.In terms of the tidal current,the average values of the root mean square velocity（RMSV） are 7.5 cm/s and 6.9 cm/s on springs and neaps,respectively.For the RMSVs that are higher than 4 cm/s,a significant positive correlation is found between the content of the 63–125 μm fraction and the RMSV,suggesting that the RMSV determines the variability of the very fine sand fraction.Based on system cluster and principal component analyses（PCA）,the modern sedimentary environments are classified into three types according to the grain size parameters,RMSVs and water depth data.The results suggest the importance of grain size parameters and high-spatial resolution hydrodynamic data in differentiating the coastal sedimentary environments.

Study on the Geo-Environmental Evolution of the Laolonggou Lagoon Under the Impacts of the Caofeidian Reclamation Project in Hebei Province

The Caofeidian Reclamation Project has been the biggest reclamation project in China so far, in which 310 km^2 sea areas were reclaimed along the coast of Hebei Province, and it also bring about many problems and defects for large reclaiming area. The study focuses on the influences of the engineering exerted on evolution of the Laolonggou Lagoon with the methods of topographical measurement and surface sediment analysis. The results demonstrate that the topographical changes in the Laolonggou Lagoon had been controlled obviously by the engineering at three stages. Besides, blocking and reopening of the shoal tidal channel also affected the geological environment of the lagoon area. In the aspect of topographical change, the Laolonggou Inlet first experienced deposition after the shoal tidal channel was blocked, followed by short-time eroding for quarrying and cofferdam construction in the east, then depositing slowly after the reclaiming activity ceased, and finally eroding after the shoal tidal channel was reopened. The project, particularly cofferdam construction led to the movement of the Laolonggou Inlet axis from west to east for 50 – 100 m. In the aspect of sediment variation, the reclamation project and hydrodynamic change resulted in the variation in compositions and distribution pattern. The western lagoon area has become land mainly constituted by silt, while the sediments in the eastern area have turned finer in size. After the shoal tidal channel was reopened, the current velocity in the Laolonggou Inlet has been enhanced, making the sediments at the bottom become coarser. The sediments around the Caofeidian foreland went through a process of changing in grain size from fine to coarse and back to fine again, and the sediments are mainly constituted by silt at present.

The Geochemistry of Heavy Metals in the Mudflat of Salinas de San Pedro Lagoon, California, USA

Sediment core samples were collected from the Salinas de San Pedro to assess the pollutant deposition processes in response to extensive human activities. Analysis of the sediment samples for heavy metals and some trace elements was conducted with ICP-OES for 20 sites showing enrichment for some of trace and heavy metals. The results demonstrated that heavy metal concentrations in mud varied greatly for each metal, with concentration values (mg/g) ranging from 1.05 - 4.8 (Al);0.003 - 0.011(As);0.001 - 0.005 (Cd);0.02 to 0.82 (Cr);0.085 - 0.47 (Cu);5.98 - 14.22 (Fe);0.06 - 0.19 (Mn);0.03 - 0.67 (Ni);0.05 - 0.38 (Pb);- 0.069 (Se);0.18 - 0.63 (Ti);0.040 - 0.091 (V) and 0.149 - 0.336 (Zn). The Index of Geo-accumulation factor showed highest values for Pb, Mn, As, and Cu. Enrichment factors >1for these elements suggest anthropogenic inputs for most metals. The bioavailability of metals in lagoon sediments has the potential to be highly dynamic with local waste and natural H2S discharge from existing fault line.

The application of GPR to barrier-lagoon sedimentation study in Boao of Hainan Island

Sedimentary successions and internal structure of the coastal barrier-lagoon system of Boao, eastern Hainan Island were studied through utilizing data from test holes and trenches and ground-penetrating-radar (GPR) profiles. During late Pleistocene, fluvial and delta plains developed over an unevenly eroded bedrock during low sea level stand, followed by the formation of littoral and lagoon facies and defined coastal barrier-lagoon-estuary system during the post-glacial uppermost Pleistocene-lower Holocene eustatic rise of the sea level, and the upper Holocene high stand. GPR results show that Yudaitan, a sandy coastal bar backed by a low-laying land (shoal) just east of the active lagoon, is a continuous, parallel and slightly-wavy reflectors indicating homogeneous sandy or sandy gravel sediments, and inclined reflectors partly caused by progradation and accumulation of beach sand and gravel. Quasi-continuous, hummocky and chaotic reflectors from the shoal of Nangang village correspond to mixed accumulation of sands and clay. This research indicates the GPR is a non-intrusive, rapid, and economical method for high-resolution profiling of subsurface sediments in sandy gravelly coast.

Model of Wetland Carbon Sequestration in the Venetian Lagoon, Italy

This research deals with an evaluation of the sink of greenhouse gas CO2 in a eutrophic area of the Venetian lagoon where fish is farmed （＂Valle da pesca＂）. Following CDM UNFCCC （Clean Development Mechanism United Nations Framework Convention on Climate Change） criteria, this can be considered relevant to the international standard for the voluntary evaluation of carbon credits on the basis of Annex a of Kyoto Protocol. To identify the ＂Valle da pesca＂ brackish lagoon properties regulating the carbon dioxide （CO2）, a survey has been performed during three seasons in one year and in four different locations. These places are located in the Italian Venetian Lagoon and in the Grado Lagoon in North Italy, Europe. To identify the CO2 sink capacity, a special index is calculated. The CO2 concentrations and sink are regulated by the balance of autotrophic and heterotrophic activities, and the sediment anoxic denitrification and macro algae are crucial tank of CO2 in the valley shallow waters. The ponds potential-CO2 yield of 80-124 kg/m2 per year and the value are related and proportional to the correct human environmental control （water flux control）.

Diet and Food Consumption of the African Catfish, <i>Chrysichthys nigrodigitatus</i>Lacépède (1803) (Siluriformes: Claroteidae), from the Hydrosystem Lake Togo-Lagoon of Aného (South of Togo)

Catfishes belonging to the genus Chrysichthys are generally important fish species in inland water bodies of Africa because of their high commercial value. Among them, C. nigrodigitatus could represent, at certain periods of the year the highest biomass of the littoral ichthyofauna, accounting for 17 to 43.8% of total catches. In this paper, its diet in the hydrosystem Lake Togo-Lagoon of Aného was investigated focusing on how differences in diet and food consumption are related to size, season and sexual maturity. A total of 195 males and 137 females were sampled from January to December 2017. The digestive tract of each individual was dissected and its content was analyzed, using indexes of stomach contents analysis method. Diet variability in relation to season and biometric parameters was also studied. About 99 stomachs were empty with an overall vacuity index of 29.82%. However, vacuity index was found to vary in relation to fish size and months. The fish has been found to be omnivorous with a carnivorous tendency consuming a wide range of prey items (H = 3.34). Juvenile and adult freshwater clams (Galatea paradoxa) were the numerical dominant preys (%N = 44%) while the penaeid shrimps (Farfantepenaeus notialis) with an annual frequency of occurrence (Fo) of 49.36% and all species confused of fish (33.91%) were the most preferred preys. The index of relative importance (IRI) reveals that freshwater clam (40.49%), penaeid shrimps (35.85%) and all species confused of fish (14.58%) were the most important preys of C. nigrodigitatus. The dominance of Malacostraca and Mollusca in the diet of C. nigrodigitatus in the hydrosystem Lake Togo-Lagoon of Aného is likely one of the more important considerations for future management plans.

Reconstructing Environmental Changes of a Coastal Lagoon with Coral Reefs in Southeastern Hainan Island

Coastal lagoons with small catchment basins are highly sensitive to natural processes and anthropogenic activities. To figure out the environmental changes of a coastal lagoon and its contribution to carbon burial, two sediment cores were collected in Xincun Lagoon, southeastern Hainan Island and (210) ~Pb activities, grain size parameters, total organic carbon(TOC), total nitrogen(TN), total inorganic carbon(TIC) and stable carbon isotopes(δ^(13)C) were measured. The results show that in 1770–1815, the decreasing water exchange capacity with outer open water, probably caused by the shifting and narrowing of the tidal inlet, not only diminished the currents and fined the sediments in the lagoon, but also reduced the organic matter of marine sources. From 1815 to 1950, the sedimentary environment of Xincun Lagoon was frequently influenced by storm events. These extreme events resulted in the high fluctuation of sediment grain size and sorting, as well as the great variation in contributions of terrestrial(higher plants, soils) and marine sources(phytoplankton, algae, seagrass). The extremely high content of TIC, compared to TOC before 1950 could be attributed to the large-scale coverage of coral reefs. However, with the boost of seawater aquaculture activities after 1970, the health growth of coral species was severely threatened, and corresponding production and inorganic carbon burial flux reduced. The apparent enhanced inorganic carbon burial rate after 1990 might result from the concomitant carbonate debris produced by seawater aquaculture. This result is important for local government long-term coastal management and environmental planning.

Determination of Element Levels of Lagoon from Townships near Cocody City Abidjan Côte D’Ivoire Using Energy Dispersive X-Ray Fluorescence

Eight water bottles from Ebrie lagoon with pollution potency were studied using nuclear chemistry technique and Energy dispersive X-ray fluorescence. This pollution is characterized by pH and conductivity parameters, concentrations average in mg/L of metals such Fe (0.731), Mn (0.345), Cr (0.070), Cu (0.014) and concentrations of nutrients known to be pollutants and toxic for living or-ganisms. These heavy metals are dangerous to the lives, the local inhabitants and also a threat to aquatic life since this water is essential for the economical town, Abidjan. According to the Manganese concentration average (0.345 mg) values that higher than WHO (0.05 mg) value, the main likely source of pollu-tants is anthropogenic, industrial and agricultural. This study also shows the use of materials and lubricants near the lagoon that pollute this water.

Assessment of the environmental impact of artificial effluent lagoon in Jiayuguan City of China

An artificial effluent lagoon for storing wastewater were excavated in Jiayuguan City since 1994. As a part of a demonstration project of Sino Australia cooperation, an assessment of the environmental impact of the lagoon was carried out. The assessment was based on field and laboratory tests and predictive model. The main impacts from the lagoon site are likely to be on the groundwater system, and, to a lesser extent, on ambient air quality in the vicinity. Currently it is expected that groundwater is being polluted with effluent from the effluent lagoon. Air pollution(odor nuisance) is mainly caused by untreated effluent in the irrigation channel. The impact of high total dissolved salt(TDS) on groundwater is likely to be significant in the long run if the lagoon is continuously used. There is, consequently, no likelihood of contamination of surface water system, particularly of the city water supply system, from infiltration of effluent at the lagoon.

Estimation of the Impact of Climate Change on Water Resources Using a Deterministic Distributed Hydrological Model in Cote d’Ivoire:Case of the Aghien Lagoon

This work aims to evaluate the impact of climate change on the quantitative availability of the Aghien lagoon located in the north of the Abidjan district in C&#244;te d’Ivoire. In the first step, the semi-distributed SWAT (Soil and Water Assessment Tools) based physical model (Arnold et al., 1998) was calibrated and validated at the monthly time step over the period 1960-1981, in the Me watershed for which data from flow rates are available. SWAT was then applied on the watershed of the lagoon of Aghien which is ungauged but for which the challenges are considerable for the drinking water supply of the Abidjanese population. In the second step, the gross outputs (precipitation, temperatures) of six climate models of the CORDEX-Africa project under the “Representative Concentration Pathways” (RCP 4.5 and RCP 8.5) scenarios were corrected using the delta method. These corrected outputs were used at the SWAT model input to project the impact of climate change on the flow of the Aghien lagoon to horizons 2040 (2035-2056), 2060 (2057-2078) and 2080 (2079-2100). The projections made on these different horizons were compared with the simulated flow over the period 1960-1981. The results show a sensible decrease in the annual flow of the Aghien lagoon compared to the reference period (1960-1981). Under the medium assumption (RCP 4.5), the models predict a decrease in the annual discharge almost 10% on average. Under the pessimistic hypothesis (RCP 8.5), the average annual discharge should decrease by more than 17%. On a monthly basis, flows in August and September would increase by more than 80% and those in October and November would increase by more than 20% in both RCP scenarios.

Assessment of Changes in the Algal Diversity of Chilika Lagoon after Opening of New Mouth to Bay of Bengal

Eighty one algal taxa comprising of 24 species of Cyanophyta, 2 Rhodophyta, 19 Chlorophyta, 6 Euglenophyta and 30 Bacillariophyceae under Heterokontophyta were recorded in Chilika lagoon in different seasons of 2010-2011 in a survey after opening of new mouth to Bay of Bengal. Of these Cyanobacterium diachlloros, Aphanocapsa marina, Microsystis aeruginosa, Microsystis wesenbergii, Pseudanabena limnetica, Arthospira ambiguum, Oscillatoria perornata, Oscillatoria proteus, Oscillatoria simplicissima under Cyanophyta, Scenedesmus bijugatus, Urenema elongatum under Chlorophyata, Trachelomonas abrupt, Trachelomonas hispida under Euglenopyta and Coscinodiscus subtilis, Navicula amphirhynchus, Navicula major, Gomphonema micropus, Gomphonema olivaceu, Gomphonema sphaerophorum, Cyclotella meneghiniana, Pinnularia subsimilis, Pleurosigma javanicum, Stephanophyxis turris, Synendra tabulata, Stauroneis pusilla and Cymbella affinis under Bacillariophyceae of Heterokontophyta recorded in the survey have not been reported in the lake before opening of the mouth. Maximum number of algal species was observed in winter followed by summer and post monsoon seasons. Northern sector showed maximum algal diversity followed by Central, Southern and Outer channel sectors. The Cyanophytes followed by Chlorophytes were rich in Northern, Central and Southern sectors where as the diatoms were abundant in Outer channel sector and Northern sector. The agarophyte Gracilaria verrucosa recorded in the Outer channel sector of the lagoon for the first time showing extended distribution of the species due to increase in salinity coupled with consistent wave action in the lagoon after opening of the new mouth.

Variation in the Colonization of Artificial Substrates by Mangrove Root Fouling Species of the Port Royal Mangrove Lagoons in the Eutrophic Kingston Harbour, Jamaica

The aim of this study was to investigate temporal changes in mangrove root fouling species settled on artificial substrates in the mangrove zone of the Port Royal lagoons and to determine the effect of stress as part of a larger project to determine appropriate indicators of eutrophication in mangrove lagoons. Five Perspex? panels were suspended in the prop root zone at five contrasting stations within the Port Royal mangroves and the fouling organisms were monitored fortnightly using underwater digital photography. Nine taxonomic categories of epibionts were recorded of which the most prevalent group was the ascidians. Barnacles and hydroids were initially found to have established on the artificial substrates at all stations but were quickly replaced by ascidians and bryozoans at most. Species composition was similar between all stations by the end of the study, however, the dominant taxa were different. Sheltered lagoons like Fort Rocky lagoon (north and south) had a clear dominance of non-shelled species (ascidians and polychaetes) by the end of the study, while molluscs- bivalves and barnacles dominated Hurricane Refuge lagoon. This station, deemed to be experiencing greatest stress due to exposure to the eutrophic Kingston Harbour, also had the greatest proportion of shelled taxa represented in the epibiont biomass at the end of the study. Differences in biomass and species composition of root fouling species can therefore be used to indicate water quality in the mangrove lagoons.