Tropical Coastal Environment Research Articles

Characterization of phytoplankton assemblages in a tropical coastal environment using Kohonen self‐organizing map

AbstractThis study was aimed at understanding the main abiotic environmental factors controlling the distribution patterns of abundance and composition of phytoplankton (size less than 10 μm) assemblages in the coastal waters of south‐eastern Côte d'Ivoire. Data were collected during two cruises, in January (low‐water period) and October (high‐water period) of 2014. A total of 67 species were identified and assigned to Bacillariophyceae (49%), Cyanophyceae (21%), Chlorophyceae (13%), Euglenophyceae (10%), Dinophyceae (4%) and Chrysophyceae (3%). Three biotic zones (I, IIA and IIB) were distinguishable on a Kohonen self‐organizing map after an unsupervised learning process. The diatom genera Eunotia sp., Navicula sp. and Actinoptychus senarius are significantly associated with I, IIA and IIB biotic zones, respectively. A clear seasonal cum salinity trend was apparent in phytoplankton distribution patterns. Turbidity and nitrate levels were the main abiotic factors controlling phytoplankton distribution in I, the upland tidal regions of the lagoon. In regions along the lagoon–sea continuum, phosphate and turbidity exert the most control during the low‐water season (IIA), while total dissolved solids control phytoplankton distribution during the high‐water season (IIB). These are climate‐sensitive parameters whose concentrations depend on prevailing hydroclimatic processes. Therefore, seasonality can have important consequences on phytoplankton community and inadvertently the productivity of these systems.

Air-sea exchange of gaseous mercury in the tropical coast (Luhuitou fringing reef) of the South China Sea, the Hainan Island, China.

The air-sea exchange of gaseous mercury (mainly Hg(0)) in the tropical ocean is an important part of the global Hg biogeochemical cycle, but the related investigations are limited. In this study, we simultaneously measured Hg(0) concentrations in surface waters and overlaying air in the tropical coast (Luhuitou fringing reef) of the South China Sea (SCS), Hainan Island, China, for 13days on January-February 2015. The purpose of this study was to explore the temporal variation of Hg(0) concentrations in air and surface waters, estimate the air-sea Hg(0) flux, and reveal their influencing factors in the tropical coastal environment. The mean concentrations (±SD) of Hg(0) in air and total Hg (THg) in waters were 2.34 ± 0.26ngm(-3) and 1.40 ± 0.48ngL(-1), respectively. Both Hg(0) concentrations in waters (53.7 ± 18.8pgL(-1)) and Hg(0)/THg ratios (3.8%) in this study were significantly higher than those of the open water of the SCS in winter. Hg(0) in waters usually exhibited a clear diurnal variation with increased concentrations in daytime and decreased concentrations in nighttime, especially in cloudless days with low wind speed. Linear regression analysis suggested that Hg(0) concentrations in waters were positively and significantly correlated to the photosynthetically active radiation (PAR) (R (2) = 0.42, p < 0.001). Surface waters were always supersaturated with Hg(0) compared to air (the degree of saturation, 2.46 to 13.87), indicating that the surface water was one of the atmospheric Hg(0) sources. The air-sea Hg(0) fluxes were estimated to be 1.73 ± 1.25ngm(-2)h(-1) with a large range between 0.01 and 6.06ngm(-2)h(-1). The high variation of Hg(0) fluxes was mainly attributed to the greatly temporal variation of wind speed.

Characterisation of particle mass and number concentration on the east coast of the Malaysian Peninsula during the northeast monsoon

Particle mass concentrations (PM10, PM2.5 and PM1) and particle number concentration ((PNC); 0.27 μm ≤ Dp ≤ 34.00 μm) were measured in the tropical coastal environment of Bachok, Kelantan on the Malaysian Peninsula bordering the southern edge of the South China Sea. Statistical methods were applied on a three-month hourly data set (9th January to 24th March 2014) to study the influence of north-easterly winds on the patterns of particle mass and PNC size distributions. The 24-h concentrations of particle mass obtained in this study were below the standard values detailed by the Recommended Malaysian Air Quality Guideline (RMAQG), United States Environmental Protection Agency (US EPA) and European Union (EU) except for PM2.5, which recorded a 24-h average of 30 ± 18 μg m−3 and exceeded the World Health Organisation (WHO) threshold value (25 μg m−3). Principal component analysis (PCA) revealed that PNC with smaller diameter sizes (0.27–4.50 μm) showed a stronger influence, accounting for 57.6% of the variability in PNC data set. Concentrations of both particle mass and PNC increased steadily in the morning with a distinct peak observed at around 8.00 h, related to a combination of dispersion of accumulated particles overnight and local traffic. In addition to local anthropogenic, agricultural burning and forest fire activities, long-range transport also affects the study area. Hotspot and backward wind trajectory observations illustrated that the biomass burning episode (around February–March) significantly influenced PNC. Meteorological parameters influenced smaller size particles (i.e. PM1 and Dp (0.27–0.43 μm)) the most.

Ant dominance hierarchy determines the nested pattern in ant-plant networks

Extrafloral nectar (EFN) is a predictable and renewable resource for many ant colonies, and different ant species compete strongly to obtain and monopolize this highly nutritious food resource. Despite the importance of competition in structuring patterns of ant–plant interactions, this biological mechanism has been largely ignored in studies involving ant–plant networks. In this study we investigate the role of ant dominance hierarchy in structuring an ecological network involving ants and EFN-bearing plants in a tropical coastal environment in Mexico. We show that within a nested ant–plant network, ant species found in the central core of highly interacting species were competitively superior, showing massive recruitment and resource domination, compared with peripheral species with fewer interactions. Moreover, we also observed that both central and peripheral ant species have the ability to quickly find the food resource. However, after 2 h of observation, central ant species are more frequently collected on the food resource when compared with peripheral species. We hypothesize that the existence of a central core of competitive ant species may indicate that most plant species found within ant–plant networks could be better protected against herbivory by these dominant ant species. In short, our results highlight the importance of competition and monopolization in the resource use by ants in the maintenance of the nested pattern in ant–plant mutualistic networks. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 405–414.

Seasonality in the distribution of dinoflagellates with special reference to harmful algal species in tropical coastal environment, Bay of Bengal.

A study was carried out in the coastal waters of Kalpakkam, southeast coast of India, to find out the seasonal variation in dinoflagellate community structure. Samples were collected for a period of 4 years during 2006-2010. During the study 69 species of dinoflagellates were encountered among which Ceratium furca and Prorocentrum micans were most common during all the seasons. Genus Ceratium was found to be the most diverse one with 23 species which was followed by genus Protoperidinium with 16 species. Of 69 species, 27 species were considered as dominant based on their abundance during pre-monsoon (PRM), monsoon (MON) and post-monsoon (POM) periods. Relatively high density and diversity of dinoflagellates were encountered during the PRM period as compared to the MON and POM periods. Abundance pattern of dinoflagellates for three seasons showed the following trend: PRM > POM > MON. Salinity showed a positive correlation with dinoflagellate community showing its importance in dinoflagellate growth and sustenance. Ammonia and phosphate developed negative correlation with dinoflagellate density indicating the utilization of these nutrients by the dinoflagellate community. The presence of three dinoflagellate associations, broadly representing the three seasons experienced at this location, was evident from the cluster analysis. The study revealed presence of 19 relatively abundant toxic/red tide forming dinoflagellate species in the coastal waters of Kalpakkam.

Persistent organic pollutants in tropical coastal and offshore environment: part A—atmospheric polycyclic aromatic hydrocarbons

Air samples were collected at four sites from August 2009 to May 2010. Temporal variation of polycyclic aromatic hydrocarbon (PAH) concentrations showed the highest concentration in November and the lowest in May, except for one case attributable to a specific meteorological event, a typhoon, which resulted in a dramatic increase in PAHs concentrations. PAH compositional pattern, diagnostic ratios, hierarchical cluster analysis, and principal component analysis indicated that the major sources of PAHs in the Gaoping coastal area were local vehicle emissions, stationary sources, and coal/wood combustion. In addition, the distinct compositional patterns at each sampling site suggested that sources of PAHs varied with sampling periods. Back trajectory analysis indicated that transport pathway and moving speed of air parcels were two important factors that influence temporal and spatial variation of PAH concentrations. Air parcel pathways and PAH compositional patterns also indicated that PAHs observed at an offshore island (Liu-Chiu Isle) in November were affected by sources in the southwest coastal area of Taiwan. The data set of PAH concentrations built in this study provides useful information to estimate air–water exchange behavior of PAHs and to investigate the fate of PAHs in the Gaoping coastal area.

Feeding habits and food partitioning between three commercial fish associated with artificial reefs in a tropical coastal environment

At Réunion Island (south-western Indian Ocean), artificial reefs were submerged in 2003 in a bay and were soon colonised by fish, among which were the highly abundant commercial species Lutjanus kasmira, Priacanthus hamrur and Selar crumenophthalmus. The high concentration and diversity of fish around the artificial reefs is surprising, considering the low abundance of potential benthic prey. We investigated the diet and food partitioning between the aforementioned species using stomach content and stable isotope analyses (δ13C, δ15N). Priacanthus hamrur and S. crumenophthalmus fed on a larger prey diversity and showed significant overlap in their diets, with crustacean larvae the dominant prey. Fish larvae dominated L. kasmira's diet, and δ15N values confirmed the species’ higher trophic level. Differences in δ13C between P. hamrur and S. crumenophthalmus indicated niche segregation, probably as a way to reduce competition, with P. hamrur being characterised by a smaller δ13C range and exhibiting a smaller isotopic niche than S. crumenophthalmus. There was a significant correlation between δ15N and fish standard length for the three species, suggesting that ontogeny partially explained the niche breadth. There was also a significant correlation between δ13C and length for L. kasmira, whereas individual specialisation was prevalent in S. crumenophthalmus.

Emission of atmospherically significant halocarbons by naturally occurring and farmed tropical macroalgae

Abstract. Current estimates of global halocarbon emissions highlight the tropical coastal environment as an important source of very short-lived (VSL) biogenic halocarbons to the troposphere and stratosphere, due to a combination of assumed high primary productivity in tropical coastal waters and the prevalence of deep convective transport, potentially capable of rapidly lifting surface emissions to the upper troposphere/lower stratosphere. However, despite this perceived importance, direct measurements of tropical coastal biogenic halocarbon emissions, notably from macroalgae (seaweeds), have not been made. In light of this, we provide the first dedicated study of halocarbon production by a range of 15 common tropical macroalgal species and compare these results to those from previous studies of polar and temperate macroalgae. Variation between species was substantial; CHBr3 production rates, measured at the end of a 24 h incubation, varied from 1.4 to 1129 pmol g FW−1 h−1 (FW = fresh weight of sample). We used our laboratory-determined emission rates to estimate emissions of CHBr3 and CH2Br2 (the two dominant VSL precursors of stratospheric bromine) from the coastlines of Malaysia and elsewhere in South East Asia (SEA). We compare these values to previous top-down model estimates of emissions from these regions and, by using several emission scenarios, we calculate an annual CHBr3 emission of 40 (6–224 Mmol Br−1 yr), a value that is lower than previous estimates. The contribution of tropical aquaculture to current emission budgets is also considered. Whilst the current aquaculture contribution to halocarbon emissions in this regional is small, the potential exists for substantial increases in aquaculture to make a significant contribution to regional halocarbon budgets.

Role of water temperature in the fate and transport of zinc oxide nanoparticles in aquatic environment

The influence of water temperature on the aggregation and dissolution kinetics of zinc oxide nanoparticles (ZnO NPs) (mean diameter ~40 nm) was investigated. Samples of 100 mg.L−1 ZnO NPs were incubated at 15, 25 and 35 °C, similar to the surface temperature of cold freshwater, temperate estuarine, and tropical/sub-tropical coastal marine ecosystems, respectively. The natural organic matter (NOM) content, pH, electrolyte type, and ionic strength (IS), were adjusted on the basis of the water chemistries of typical aqueous systems. Specifically, the time-dependent hydrodynamic diameters (HDDs) and sedimentation plots were obtained over the first 3 h and after 24 h using time-resolved dynamic light scattering (TR-DLS) and UV-visible spectroscopy, respectively. The settling distance was further modeled for the aggregates with various HDDs according to the Stokes' sedimentation equation. The dissolution kinetics was studied over the first 12 h and after 48 h in term of percentage of released zinc ions.The results showed that the HDD increased at elevated temperatures, termed as temperature-induced aggregation, while dissolution was reduced. The aggregation at higher temperatures further hindered the dissolution due to the decrease in the surface area of the NPs. We express this process as "aggregate-suppressed dissolution". The maximum aggregation was reached in the tropical coastal marine environment with the HDD >3 μm, and the released zinc ion of 9.2% was obtained in the cold freshwater. Based on the results, the aggregation rate of 1.57 nm.s−1 was estimated for the former, and the dissolution rate of 7.44 × 10−5 mol.L−1.h−1 was calculated for the latter, respectively. The predicted values successfully fitted to genuine water samples (<26% deviation). This study provides useful data for environmental risk assessment of exposure of ZnO NPs to water column and benthic organisms.

Sexual maturity of the swimming crab Callinectes danae (Crustacea: Portunidae) at the Santa Cruz Channel, a tropical coastal environment

This paper aims to study the morphological and gonadal maturity of the swimming crab Callinectes danae in the Santa Cruz Channel, Brazil. Crabs of both sexes were measured at carapace width (CW), carapace length (CL), abdomen width (AW), length of the right chelipod (LRC), and dissected to visualize the gonads. The gonadal maturity was estimated based on the frequency of mature individuals per class of CW, and the determination of morphological maturity was based on the relationship between the structures LRC versus CW for males and AW versus CW for females. The sizes that 50% of females reached gonadal and morphological maturity were 62.5 and 59.5 mm CW respectively. In turn, the sizes that 50% of males reached gonadal and morphological maturity were 74.5 and 70.5 mm CW respectively. In the analysis of dispersion of points in relation to AW versus CW, it could be observed that juvenile females showed positive allometry and adult females showed negative allometry, indicating a higher growth rate during the juvenile phase, related to the need of expanding the abdomen for egg incubation at the adult phase. In the relation LRC versus CW, it was observed that both juvenile and adult males showed positive allometry, but changes in the degree of allometry were evident between the two phases. The exceeding growth of the chelipod of males may be related to the reproductive process, including courtship and agonistic interactions with other males.

The challenge of small and rare species in marine biodiversity surveys: microgastropod diversity in a complex tropical coastal environment

Although molluscs feature prominently in the semi-popular and academic literature on marine biodiversity, field surveys largely ignore the small and rare species that form the majority of marine molluscan diversity. As a result of a massive effort to sample the benthic molluscs of a complex tropical coastal environment, 23,238 gastropod specimens representing 259 species of Triphoridae—a family with most adult species ranging from 2 to 10 mm—were obtained from a 45,000 hectares study area off the island of Espiritu Santo, Vanuatu. Most species are represented by fewer than 20 specimens and, despite the intensity of the sampling effort, 13% of the species are unique singletons. Spatial heterogeneity was high: out of 416 sampling events, 187 contained triphorids, and 42% of the species occurred at fewer than 5 stations. Most species were small (68% below 5 mm) or very small (22% below 3 mm). A faunal turnover was documented at around 10 m, and another at around 60 m, at the onset of the “twilight zone” that is particularly difficult to sample. On the order of 70% of the species are probably new to science. When dealing with taxonomically difficult groups a morphospecies segregation approach is operationally appropriate to detect patterns of richness, rarity and spatial turn-over. Very few, if any, conservation surveys have the human and funding resources to carry out baseline surveys of the intensity that generated the results presented here. However, as species numbers are often used to promote the conservation interest of a reef, a bay or a stretch of coast, it is essential to know how the numbers were generated: absolute numbers of species are meaningless unless sampling effort and techniques, area surveyed, and size classes targeted are described. This is very rarely the case, even in the academic literature.

Subtidal microphytobenthos: effects of inorganic and organic compound supplies on migration, production, and respiration in a tropical coastal environment

Microphytobenthos (MPB) is an important primary producer in coastal ecosystems. In oligotrophic environments, its activity may be controlled by the availability of organic or inorganic compounds but also by its migration behavior. The objective of this study was to determine, in MPB-colonized subtidal sediments, the consequences of short-term enrichments (< 24 h) of organic (alanine, glutamate, and glucose) and inorganic (ammonium, phosphate) compounds on MPB vertical migration and metabolisms, net production (NP), areal gross production (AGP), and community respiration (R). Two contrasting stations located in the southwest lagoon of New Caledonia were investigated: 1 under strong anthropogenic influence and 1 under more oceanic influence. Both stations were dominated by epipelic diatoms. Differences in net primary production were explained by diurnal variation of MPB biomass at the sediment surface, showing the importance of MPB migration in the functioning of these subtidal environments. However, a stimulation or inhibition of MPB migration did not necessarily impact the net primary production of the system; this strongly depends upon the interactions between the autotrophic and heterotrophic compartments, the latter being controlled by the environmental conditions. For the station under low anthropogenic influence, AGP and R were both significantly stimulated by alanine, glucose, and ammonium, and significantly inhibited by phosphate. The similar responses of AGP and R to enrichments suggest that autotrophs and heterotrophs were tightly coupled. Conversely, in the station under strong anthropogenic influence, AGP and R responded differently. Addition of ammonium inhibited AGP without having an impact on R, whereas addition of phosphate inhibited R whilst having no measurable effect on AGP. In this station, the coupling between autotrophs and heterotrophs was weakened, suggesting that the carbon demand of the heterotrophic compartment is probably sustained by the supplies of allochthonous organic matter rather than by exudates from the autotrophic compartment.

Biofilm development on acrylic coupons during the initial 24 hour period of submersion in a tropical coastal environment

Abstract The sequence of biofilm formation on a hard surface during the first 24 hours in a coastal environment was studied by suspending acrylic coupons. Adsorption of carbohydrates, proteins, calcium, magnesium, nitrite, nitrate and phosphate were monitored along with microbes. The results showed that carbohydrate, protein, nitrite and nitrate were adsorbed on the coupons within an hour of exposure. Carbohydrates showed a maximum value of 0.28 mg cm-2 after 24 hours and protein concentration reached up to a maximum of 0.41 mg cm-2. Adsorption of calcium and magnesium was observed after three hours. Settlement of bacteria was also observed on coupons within an hour and diatoms were observed after 15 hours. Diatoms such as Navicula and Nitzschia were the dominant colonizers during the early stages of biofilm development.

Shock-capturing Boussinesq-type model for nearshore wave processes

This paper describes the formulation and validation of a nearshore wave model for tropical coastal environment. The governing Boussinesq-type equations include the conservative form of the nonlinear shallow-water equations for shock capturing. A Riemann solver supplies the inter-cell flux and bathymetry source term, while a Godunov-type scheme integrates the evolution variables in time. The model handles wave breaking through momentum conservation with energy dissipation based on an eddy viscosity concept. The computed results show very good agreement with laboratory data for wave propagation over a submerged bar, wave breaking and runup on plane beaches as well as wave transformation over fringing reefs. The model accurately describes transition between supercritical and subcritical flows as well as development of dispersive waves in the processes.

Corrosion Performance of Concrete Columns after Localized Repairs in a Tropical Coastal Environment

Abstract The tropical climate present in the Yucatan Peninsula is one of the most aggressive environments found in Mexico, which results in many concrete structures being affected by corrosion. Several types of primers, which are locally available, are used as prevention and/or repair methods for reinforcement steel found in concrete structures. Nonetheless, such primers are not designed to be used under alkaline environmental conditions. The objective of this investigation was to evaluate the efficiency of these primers used to repair concrete columns of buildings exposed to a coastal marine environment in southeast Mexico. The repair method used involved the following steps: removal of the old concrete, cleaning the rebar with a brush, applying primer to the reinforcement steel, and finally applying bonding agent and new concrete cover. The electrochemical behavior of repaired and adjacent (non-repaired) zones was monitored based on electrochemical techniques with the use of a commercially confined-curr...

Management of the coastal biophysical environment in tropical Queensland under conditions of heavy developmental pressure: the case of tourist resorts and acid sulphate soils

The tropical coast of Queensland, Australia is experiencing rapid population and tourism growth. Heavy development pressure is being placed on the biophysical environment, which includes the largest sand island in the world (World Heritage listed), Fraser Island. Despite the existence of State planning legislation oriented towards environmental sustainability, it is apparent that little, if any, regard is being paid to the long-term effects of resort and canal-estate development on the underlying biophysical environment of the coast and islands. While the remarkable surface features of the tropical coastal environment such as the surf beaches, the unique dune lakes, and the coastal vegetation, as well as the prolific wildlife, are used as selling points for new settlement and above all tourism, little is known or apparently of major concern with respect to the long term environmental impact of coastal development. While the crowding effect of large numbers of visitors and their impact on the natural environment - through significant degradation, site hardening or lack of proper on-site management – has been identified as a particular problem in certain areas, there is little knowledge of impacts on the underlying coastal geomorphology. In particular, developmental choices are often made in ignorance of, or disregard of, the widespread existence of tropical acid sulfate soils in that coastal environment. Reactive soils such as these can, and do, greatly affect the biophysical outcomes of a development if they are exposed. This paper documents such impacts in the form of a case study of the acid sulfate soil problem in relation to the development of tourist resorts, and suggests that part of the solution is for the State Government to insist on enforceable standards relating to their development for tourism in the coastal zone. These would reduce the use by many resort owners of fancy golf course developments as an environmental cover up to make it look as if they put a lot of effort into protecting the environment….

Effects of industrial outfalls on tropical macrobenthic sediment communities in Reunion Island (Southwest Indian Ocean)

Temporal changes in the composition of soft bottom macrobenthic assemblages at Reunion Island (Southwest Indian Ocean) were studied in the context of a long-term environmental monitoring programme studying the impacts of effluents of industrial sugar cane refineries that are transferred to shallow and deep coastal environments by different pathways: surface discharge and deep underground injection. Seven stations (between 20 and 160 m depth) were surveyed between 1994 and 2003 on the industrial zone. One additional station was surveyed on a reference site. Spatio-temporal changes in the composition of macrobenthic communities were assessed using several diversity indices, ABC curves, MDS and associated ANOSIM tests and biotic indices. Among the 171 taxa recorded, polychaetes were dominant (89 species), followed by crustaceans and molluscs. The analysis of spatial changes in the composition of macrobenthos showed the existence of distinct benthic communities along the depth gradient. Temporal changes in macrobenthos composition were most prominent at the shallowest station. They mainly corresponded to the decline of several initially dominant taxa and the increase of the Eunicid polychaete Diopatra cuprea. This station further showed increasing macrofaunal abundance, biomass and sediment organic content over time, concomitant with decreasing sediment grain sizes. In deeper environments, temporal changes were much smaller. Macrofaunal abundance and species richness increased progressively, suggesting a moderate impact on benthic ecosystems resulting from slight enrichments due to effluents rich in organic matter. Our results highlight an original response to disturbance pattern involving opportunistic Eunicidae species ( D. cuprea) not previously described. Moreover, they allow for the comparison of the impact on macrofauna caused by industrial effluents exported by two distinct and different pathways in a tropical coastal high-energy marine environment.

Reproduction in Balanus amphitrite Darwin (Cirripedia: Thoracica): influence of temperature and food concentration

Balanus amphitrite, an acorn barnacle, is distinctly euryhaline, eurythermal and a dominant fouling organism found in warm and temperate waters throughout the world. In this study, the influence of temperature and food concentration on the reproductive biology of this species collected from a tropical habitat was evaluated. Adult barnacles were maintained at 20, 25 and 30°C temperatures at different concentrations of food (50, 100, 150 and 200 Artemia ind−1 day−1). In this previously believed obligatory cross-fertilizing hermaphrodite, self-fertilization was observed. The rise in temperature from 20 to 30°C resulted in a longer interbreeding interval (6–7 days, 200 Artemia ind−1 day−1; 11–13 days, 50 Artemia ind−1 day−1). Computed carbon gained through feeding during the interbreeding interval indicated an inverse relationship to the temperature. At 20°C, although a greater amount of carbon was gained through feeding, the numbers of larvae produced were fivefold less when compared to those raised at 30°C. At 20°C, 2.3 μg C was required to produce a single larva, whereas at 30°C it was 0.4 μg C. A rise in rearing temperature also influenced the molting rate positively. Observations on temporal variation in the gonad development of this species in a tropical coastal environment influenced by the monsoons indicated gonad development to be positively related to chlorophyll a concentration.

GIS and Remote Sensing Applications in the Assessment of Change within a Coastal Environment in the Niger Delta Region of Nigeria

In the last decades, the Niger Delta region has experienced rapid growth in population and economic activity with enormous benefits to the adjacent states and the entire Nigerian society. As the region embarks upon an unprecedented phase of economic expansion in the 21st century, it faces several environmental challenges fuelled partly by the pressures caused by human activities such as oil and gas exploration, housing development, and road construction for transportation, economic development and demographic changes. This continued growth has resulted in environmental problems such as coastal wetland loss, habitat degradation, and water pollution, gas flaring, destruction of forest vegetation as well as a host of other issues. This underscores the urgent need to design new approaches for managing remote costal resources in sensitive tropical environments effectively in order to maintain a balance between coastal resource conservation and rapid economic development in developing countries for sustainability. Notwithstanding previous initiatives, there have not been any major efforts in the literature to undertake a remote sensing and GIS based assessment of the growing incidence of environmental change within coastal zone environments of the study area. This project is an attempt to fill that void in the literature by exploring the applications of GIS and remote sensing in a tropical coastal zone environment with emphasis on the environmental impacts of development in the Niger Delta region of Southern Nigeria. To deal with some of the aforementioned issues, several research questions that are of great relevance to the paper have been posed. The questions include, Have there been any changes in the coastal environment of the study area? What are the impacts of the changes? What forces are responsible for the changes? Has there been any major framework in place to deal with the changes? The prime objective of the paper is to provide a novel approach for assessing the state of coastal environments while the second objective seeks a contribution to the literature. The third objective is to provide a decision support tool for coastal resource managers in the assessment of environmental impacts of development in tropical areas. The fourth objective is to assess the extent of change in a tropical ecosystem with the latest advances in geo-spatial information technologies and methods. In terms of methodology, the paper draws from primary and census data sources analyzed with descriptive statistics, GIS techniques and remote sensing. The sections in the paper consist of a review of the major environmental effects and factors associated with the problem: initiatives and mitigation measures. The project offers some recommendations as part of the conservation strategies. In spite of concerted efforts by managers to address the problems, results revel that the study area experienced some significant changes in its coastal environments. These changes are attributed to socio-economic and environmental variables.

Baseline data analysis as a tool for predicting the conservation value of tropical coastal habitats in the Indo-Pacific

Coral Cay Conservation, a United Kingdom-based not-for-profit organization, operates using teams of international volunteers to conduct coral reef and tropical marine resource assessments in order to provide a baseline of data to facilitate marine resource management. This modus operandi provides the resources necessary to conduct a detailed study at minimal cost to the host country partners. This paper introduces a technique of data analysis to define the conservation value of the shallow (<30 m) tropical coastal environment. All data initially undergoes multivariate analysis to define discrete benthic habitat classes using the methods described by Mumby and Harborne [Development of a systematic classification scheme of marine habitats to facilitate regional management and mapping of Caribbean coral reefs. Biological Conservation 1999;88:155–63]. Subsequent analysis of benthic and reef fish data in terms of biodiversity and reef health indices allows spatial comparison of sites of differing conservation value and the geographic delineation of areas suitable for Marine Protected Area status.