Tropical Coasts Research Articles

Airborne synthetic-aperture radar (SAR) imaging to help assess impacts of stationary fishing gear on the north Brazilian mangrove coast

Abstract Assessing artisanal fishing effort and catches in remote tropical coastal areas is a continuous challenge for fisheries data collection. This is the first spatio-temporal analysis of the large tidal weir (LTW) fishery operating on intertidal sand banks along the world’s longest mangrove coast, north Brazil. Airborne synthetic-aperture radar (SAR) images and aerial photos were integrated with field sampling to investigate catch and discard compositions of seven LTW during the main fishing season. LTW measurements on the SAR images were used to generate estimates on daily catch, wood extraction, and sand accumulation. In a coastal stretch of 67 km, 793 LTW were identified on SAR images from 2004, including 573 active LTW. The number of active LTW in Taperaçú Bay and Caeté Bay had increased from 87 in 1998 to 132 in 2004 (52% increase), and from 92 to 202 (106% increase), respectively. Sixty-five fish species from 24 families were captured in the LTW. Ariidae, Sciaenidae, Haemulidae, and Carangidae accounted for 45, 20, 10, and 7% of the total sampled catch weight of 3441 kg, respectively. The mean daily catch per LTW was 110 kg ± 9 SE. Total discards in outer estuarine LTW were >3 times higher than in inner estuarine LTW. All Aspredinidae, Belonidae, Tetraodontidae, and Trichiuridae, and >75% of Auchenipteridae, Clupeidae, Engraulidae, Ephippidae, Loricariidae, Scombridae, and Soleidae were discarded. The LTW fishery apparently practices balanced harvesting; however, the massive LTW increase suggests fishing effort reduction to moderate levels. Mangrove wood extraction for LTW construction (22 835 m3 or 855 390 trees) and sand accumulation (144 802 m3) likely have only local scale effects, negligible for the overall ecosystem dynamics. The study highlights the potential of SAR images for use in fisheries data collection and management of tropical coasts, emphasizing the need for integration with ground-truthing field studies.

Response of mangroves to the change in tidal and fresh water flow – A case study in Pichavaram, South India

Mangroves grow in intertidal zone of tropical coasts and nourished by the influence of freshwater and tidal water added to local rainfall. This study attempts to spatially analyse such hydrological influence on the mangrove area over seven decades in Pichavaram, a wetland of South Indian East coast. Analysis of local rainfall, freshwater and tidal flow and spatial maps derived using Geographic Information System was carried out to interpret the influence of hydrological parameters on the extent of mangroves. The analysis shows that mangrove area has a positive correlation of 0.98 with amount of freshwater and 0.66 with tidal flow in terms of estuarine dimensions till 1991. After 1991, mangrove area is increased even with reduced amount of freshwater. Major reason for the increase in mangrove forest cover was the restoration of the wetland by avoiding stagnation of tidal water in degraded area and thereby reducing soil to support mangrove regeneration. However, this manipulation of local hydrological condition supported only one species of mangroves Avicennia marina, which is tolerant to high salinity. As indicated in this study freshwater inflow is one of the main factors that determine species diversity of mangrove plants since most of the mangrove species requires moderate saline condition for their optimal growth and biomass production. However, due to increased demand for freshwater upstream, amount of freshwater reaching mangroves are reduced. It is suggested that in order to at sustain mangrove wetlands suitable management procedures need to be evolved and applied to ensure required quantity of freshwater flow into mangrove ecosystem for required duration.

First records ofBarringtonia asiatica(Lecythidaceae) from UK waters and a review of north-western European records

The tree that produces the Box Fruit is known as the Fish Poison or Sea Poison Tree, Barringtonia asiatica (L.) Kurz, which is native to mangrove habitats on tropical coasts and islands in the Indi...

Transforming management of tropical coastal seas to cope with challenges of the 21st century

Over 1.3 billion people live on tropical coasts, primarily in developing countries. Many depend on adjacent coastal seas for food, and livelihoods. We show how trends in demography and in several local and global anthropogenic stressors are progressively degrading capacity of coastal waters to sustain these people. Far more effective approaches to environmental management are needed if the loss in provision of ecosystem goods and services is to be stemmed. We propose expanded use of marine spatial planning as a framework for more effective, pragmatic management based on ocean zones to accommodate conflicting uses. This would force the holistic, regional-scale reconciliation of food security, livelihoods, and conservation that is needed. Transforming how countries manage coastal resources will require major change in policy and politics, implemented with sufficient flexibility to accommodate societal variations. Achieving this change is a major challenge – one that affects the lives of one fifth of humanity.

Importance of Mangrove Carbon for Aquatic Food Webs in Wet–Dry Tropical Estuaries

Mangroves are traditionally considered to provide important nutrition to tropical estuarine consumers. However, there is still controversy about this, and the extent and importance of these inputs are largely unquantified. In particular, there is no information for food webs of small estuaries that dominate wet–dry tropical coasts, where freshwater inflow is intermittent, leading to highly seasonal inputs of nutrients from terrestrial systems. Since the relative importance of the different sources depends on the type and extent of different habitats and on hydrological and topographic conditions, results from other regions/type of systems cannot be extrapolated to these estuaries. Here, δ13C is used to determine the importance of mangrove-derived carbon for Penaeus merguiensis (detritivore; shrimp), Ambassis vachellii (planktivore; fish), and Leiognathus equulus (benthivore; fish) from six small wet–dry tropical estuaries that differ in mangrove (C3) cover and in type of terrestrial vegetation adjacent to the estuary. Bayesian mixing models confirmed that mangrove material was important to consumers in all estuaries. There was a gradient in this importance that agreed with the extent of mangrove forests in the estuaries, as C3 sources were the most important contributors to animals from the three estuaries with the greatest (>40 %) mangrove cover. There was also evidence of incorporation of C3 material for the three estuaries with lower (<30 %) mangrove cover. Since these latter estuaries had no adjacent terrestrial C3 forests, the detected C3 influence can only be of mangrove origin. This shows that mangroves are important contributors to these food webs, underlining the importance of mangroves in supporting estuarine nursery ground value and fisheries productivity.

Plastron respiration in marine intertidal oribatid mites (Acari, Fortuyniidae and Selenoribatidae)

Plastron respiration was investigated in the fortuyniid Alismobates inexpectatus, Fortuynia atlantica and the selenoribatid Carinozetes bermudensis. All these taxa inhabit intertidal zones of subtropical and tropical coasts and are exposed to tidal flooding. The utilization of plastron mechanisms enables these species to respire under water. Cerotegumental structures consisting of micropapillae and pillars bearing an outer sheet provide extensive areas where air is retained supplying the tracheal system with oxygen. A. inexpectatus and F. atlantica possess a dorsal and ventral plastron connected laterally by cuticular channels of the van der Hammen’s organ, whereas the specific configuration of these channels varies between the genera. The plastron of Carinozetes species spans the whole body except for all movable parts as legs and genital and anal valves. Plastron structures in juveniles of the families Fortuyniidae and Selenoribatidae were investigated for the first time in detail. Air-retaining cerotegument is also present in immatures of these taxa but is concentrated along lateral and ventral folds where series of pores lead into supposed tracheal organs. In juveniles of A. inexpectatus and F. atlantica, these organs are tubes with a length of approximately 3–15 μm, and in Carinozetes immatures, these organs are short saccules (0.5–1 μm).

海平面上升影响下广西钦州湾红树林脆弱性评价

Sea level rise caused by global climate change has significant impacts on coastal zone. The mangrove ecosystems occur at the intertidal zone in tropical and subtropical coasts and are particularly sensitive to sea level rise. To study the responses of mangrove ecosystems to sea level rise,assess the impacts of sea level rise on mangrove ecosystem and formulate the feasible and practical mitigation strategies are the important prerequisites for securing the coastal ecosystems. In this research,taking the mangrove ecosystems in the coastal zone of Qinzhou Bay,Guangxi province as a case study,the main impacts of sea level rise on the mangrove ecosystems were analyzed by adopting the SPRC( Source- Pathway-ReceptorConsequence) model. An indicator system for vulnerability assessment on coastal mangrove ecosystems under sea level rise was worked out,according to the IPCC definition of vulnerability,i.e. the aspects of exposure,sensitivity and adaptation.The rate of sea level rise,subsidence /uplift rate,habitat elevation,daily mean inundation duration,intertidal slope and sedimentation rate were selected as the key indicators,taking into account of the characteristics of quantification,data accessibility,spatial and temporal heterogeneity. A quantitatively spatial assessment method based on the GIS platform wasestablished by quantifying each indicator,calculating the vulnerability index and grading the vulnerability. The vulnerability assessment based on the sea-level rise rates of the present trend( the rate of sea level rise in the past 40 years),the B1 and A1FI scenarios in IPCC SRES were performed for three sets of projections of short-term( 2030s),mid-term( 2050s) and long-term( 2100s). The results showed the mangrove ecosystems in the coastal zone of Qinzhou Bay was within the grade of no vulnerability at the present sea level rise rate of 0.29 cm /a and the B1 scenario of 0.38 cm /a for the projections of2030s,2050s and 2100s,respectively. As the sedimentation and land uplift could offset the rate of sea level rise and the impact of sea level rise on habitats /species of mangrove ecosystems was negligible. While in the A1FI scenario at sea level rise rate of 0.59 cm /a,the percentage of mangrove ecosystems within the grade of low vulnerability could reach 41.3% in2050,and increased to 69.8% in 2100. The spatiotemporal occurrences of low vulnerability were mainly distributed in the northern coast of Maoweihai. The SPRC model and the methodology for vulnerability assessment developed from this study can objectively and quantitatively assess the vulnerability of coastal mangrove ecosystems in Qinzhou Bay under the impact of sea level rise caused by climate change. Based on the results from this study,some mitigation measures should be considered in the future for securing the coastal mangrove ecosystems,which include management of sedimentation,rehabilitating and recreating mangrove habitat,and controlling reclamation. The results from this study could provide a scientific basis on formulating feasible and practical mitigation strategies for coastal mangrove ecosystems under the impact of sea level rise,which is an important prerequisite for securing the coastal zone ecosystems.

열대 홍수림 주변 해역 환경 전이대의 식물플랑크톤 및 박테리아의 분포

In order to understand phytoplankton and bacterial distribution in tropical coral reef ecosystems in relation to the mangrove community, their biomass and activities were measured in the sea waters of the Chuuk and the Kosrae lagoons located in Micronesia. Chlorophyll a and bacterial abundance showed maximal values in the seawater near the mangrove forests, and then steeply decreased as the distance increased from the mangrove forests, indicating that environmental conditions for these microorganisms changed greatly in lagoon waters. Together with chlorophyll a, abundance of Synechococcus and phototrophic picoeukaryotes and a variety of indicator pigments for dinoflagellates, diatoms, green algae and cryptophytes also showed similar spatial distribution patterns, suggesting that phytoplankton assemblages respond to the environmental gradient by changing community compositions. In addition, primary production and bacterial production were also highest in the bay surrounded by mangrove forest and lowest outside of the lagoon. These results suggest that mangrove waters play an important role in energy production and nutrient cycling in tropical coasts, undoubtedly receiving large inputs of organic matter from shore vegetation such as mangroves. However, the steep decrease of biomass and production of phytoplankton and heterotrophic bacteria within a short distance from the bay to the level of oligotrophic waters indicates that the effect of mangrove waters does not extend far away.

Depositional behaviour of C-org, N, P and K in the surface sediments of two shallow water bodies in a tropical coast, India

The present paper deals with the distribution of sediment and sediment-bound nutrients in two important coastal lagoons of southern Kerala such as the Ashtamudi Estuarine Lagoon in the Kollam district and the Kadinamkulam Lagoon in the Thiruvananthapuram district. Among the two lagoons, the former is coast perpendicular, and the latter is coast parallel. An analysis of the textural characteristics reveals that, in both lagoons, the estuarine mouth and areas close to it are dominated by sand and sand-rich sediment species, indicating a high-energy depositional regime prevailing the region. On the other hand, the silt and clay dominant arms are almost sheltered and enjoy a low-energy depositional environment. The nutrient and organic carbon contents in the sheltered areas are significantly higher than the most dynamic high-energy estuarine mouth regions. This peculiar behaviour of these coastal water bodies has to be given adequate importance while laying down strategies for the conservation and management of these fragile aquatic systems in the south-western coast of India in particular and tropical coasts of the world in general.

The Role of Mountain Ranges in the Diversification of Birds

Avian faunas vary greatly among montane areas; those at high latitudes are biologically impoverished, whereas those of some low-latitude mountains are biologically very complex. Their high level of species richness is caused by the aggregation of many small-ranged species, which has been difficult to explain from purely macroecological models focusing on contemporary ecological processes. Because the individual mountain tracts harbor species that represent different evolutionary trajectories, it seems plausible to relate these species assemblages to high persistence (or absence of extinction) in addition to high levels of speciation. The distribution of small-ranged species is concentrated near tropical coasts, where moderation of the climate in topographically complex areas creates cloud forests and stable local conditions. The stability underpins specialization and resilience of local populations, and thereby the role of these places as cradles of biodiversity.

Biogeochemical behavior of organic carbon in a small tropical river and estuary, Hainan, China

The biogeochemistry of a small tropical river and estuary (the Wanquan River (WQR)) in Hainan, China, was studied to obtain information on the sources, transformation and fate of riverine organic matter. Water and total suspended matter were sampled along a salinity gradient during four field campaigns in December 2006, August 2007, July–August 2008 and April 2009. We were able to observe the effect of heavy precipitation associated with the tropical cyclone Kammuri (2008) and a strong first-rain event (2009) on the export of organic carbon. Both dissolved organic carbon (DOC) and particulate organic carbon (POC) generally decreased with increasing salinity in the estuary, with minimal seasonal or annual variations. The POC concentrations were in the range of 18–178μM for the WQR and were significantly correlated with chlorophyll a concentrations. The highest average values of DOC (∼190μM) were observed in 2009. These values could be the result of the flushing effect of the first rain. In the high-salinity zone, in situ productivity could be an important source for DOC. The δ13Corg values of particles (−29.5‰ to −23.2‰), combined with the ratio of organic carbon to total nitrogen (OC/TN), reflect a mixture of terrestrial organic matter and in situ production. The amplitudes of the POC and DOC variations on the occasion of the first-rain event of 2009 were larger than those observed during Kammuri. It is estimated that 29.8tday−1 of DOC and 10.4tday−1 of POC, representing 6–10% of the annual loads, were delivered to the coast during the 10-day period of the first flush event in 2009. Our results demonstrate the important role of short-term aperiodic events on small rivers and estuaries along tropical coasts.

Genetic differentiation within the Paralia longispina (Bacillariophyta) species complex

We report on undiscovered genetic and morphological diversity within a diatom taxon known as Paralia longispina and propose three new, extant species of Paralia — Paralia allisonii sp. nov., Paralia crawfordii sp. nov., and Paralia ehrmanii sp. nov. — obtained from subtropical and tropical coasts of the Atlantic and Pacific oceans. Comprehensive examination and hierarchical clustering of frustule characters separated these three species from each other and from P. longispina. Each species possessed one or two unique morphological diagnostic characters. The internal transcribed spacer (ITS) region and a fragment of the small subunit (18S rRNA gene) of nuclear encoded rRNA and a portion of the 5′ end of the large subunit of the ribulose bisophosphate carboxylase (rbcL) gene of the chloroplast genome were related to the morphological groupings of monoclonal isolates of P. allisonii and P. crawfordii. The ITS2 secondary structure of the cultured clones of these two species had four helices. They differed by five hemicompensatory base changes (HCBCs) and substantial changes to the distal end of helix I, the region between helix II and helix III, and nearly all of helix IV. Our results better our understanding of the distribution of subtropical and tropical species of Paralia and have practical implications for the conservation of native microbial florae and for the possibility of ship ballast in human-mediated dispersal of these diatoms.

Global Climate Change and Its Potential Impact on Disease Transmission by Salinity-Tolerant Mosquito Vectors in Coastal Zones

Global climate change can potentially increase the transmission of mosquito vector-borne diseases such as malaria, lymphatic filariasis, and dengue in many parts of the world. These predictions are based on the effects of changing temperature, rainfall, and humidity on mosquito breeding and survival, the more rapid development of ingested pathogens in mosquitoes and the more frequent blood feeds at moderately higher ambient temperatures. An expansion of saline and brackish water bodies (water with <0.5 ppt or parts per thousand, 0.5–30 ppt and >30 ppt salt are termed fresh, brackish, and saline respectively) will also take place as a result of global warming causing a rise in sea levels in coastal zones. Its possible impact on the transmission of mosquito-borne diseases has, however, not been adequately appreciated. The relevant impacts of global climate change on the transmission of mosquito-borne diseases in coastal zones are discussed with reference to the Ross–McDonald equation and modeling studies. Evidence is presented to show that an expansion of brackish water bodies in coastal zones can increase the densities of salinity-tolerant mosquitoes like Anopheles sundaicus and Culex sitiens, and lead to the adaptation of fresh water mosquito vectors like Anopheles culicifacies, Anopheles stephensi, Aedes aegypti, and Aedes albopictus to salinity. Rising sea levels may therefore act synergistically with global climate change to increase the transmission of mosquito-borne diseases in coastal zones. Greater attention therefore needs to be devoted to monitoring disease incidence and preimaginal development of vector mosquitoes in artificial and natural coastal brackish/saline habitats. It is important that national and international health agencies are aware of the increased risk of mosquito-borne diseases in coastal zones and develop preventive and mitigating strategies. Application of appropriate counter measures can greatly reduce the potential for increased coastal transmission of mosquito-borne diseases consequent to climate change and a rise in sea levels. It is proposed that the Jaffna peninsula in Sri Lanka may be a useful case study for the impact of rising sea levels on mosquito vectors in tropical coasts.

Assessing forest products usage and local residents' perception of environmental changes in peri-urban and rural mangroves of Cameroon, Central Africa

BackgroundDeforestation is one of the most ubiquitous forms of land degradation worldwide. Although remote sensing and aerial photographs can supply valuable information on land/use cover changes, they may not regularly be available for some tropical coasts (e.g., Cameroon estuary) where cloud cover is frequent. With respect to mangroves, researchers are now employing local knowledge as an alternative means of understanding forest disturbances. This paper was primarily aimed at assessing the mangrove forest products usage, along with the local people's perceptions on environmental changes, between Littoral (Cameroon estuary) and Southern (mouth of the Nyong River and Mpalla village) regions of Cameroon.MethodsThe data from both locations were obtained through conducting household interviews and field observations.ResultsIn the Cameroon estuary (Littoral region), 69.23% of respondents (mostly elders) could distinguish two to four mangrove plants, whereas the informants (65.45%) in the mouth of the Nyong River and Mpalla village (mostly young people interviewed from the Southern region) are familiar with only one or two commonly found mangroves. Also, more respondents from the Cameroon estuary are depending on mangroves for fuelwood (Rhizophora spp.) and housing (Rhizophora spp., Avicennia germinans (L.) Stearn and Nypa fruticans (Thumb.) Wurmb.) purposes, in contrast to Nyong River mouth and Mpalla village. Although local people perceived wood extraction as a greater disruptive factor, there are several causes for mangrove depletion in the Cameroon estuary. Among others, over-harvesting, clear-felled corridors, sand extraction and housing were found important. Furthermore, a decline in mangrove fauna composition (in terms of fishery products) was recorded in the Littoral as well as Southern regions. However, the causes of such perceived negative changes were not similar in both cases.ConclusionsFindings of this study highlight the need to improve sustainable management of the mangrove ecosystems through afforestation (in large impacted areas), selective removal of senescent tree stems and branches (in little damage stands), regulating sand extraction and housing activities, and creating awareness and law enforcement.

Triterpenols in mangrove sediments as a proxy for organic matter derived from the red mangrove ( Rhizophora mangle)

Mangroves are the dominant type of vegetation along many tropical coasts. Organic matter (OM) derived from mangrove leaf litter and root material is stored in sediments and is a major contributor to the amount and chemical composition of sedimentary OM. A set of organic biomarkers in sediments was applied as a palaeo-indicator for the Holocene dynamics of a mangrove Estuary (Rio Caeté, Pará, Brazil). Six sediment cores were collected perpendicular to the present coast line and analysed for triterpenols and sitosterol. The influence of microbial biomarker degradation was implemented from a previous study. Biomarker profiles were validated with pollen data and multivariate statistics to test whether these compounds were suitable indicators for the palaeo-vegetation. Sediments deposited up to 2 Ma BP showed biomarker assemblages similar to those of recent surface sediment. In two cores, the biomarker composition revealed a transition from marsh to mangrove vegetation. Taraxerol, germanicol and β-amyrin provided the most significant chemotaxonomical information and, especially in combination, served as reliable proxies for OM from Rhizophora mangle in northern Brazil. The maximum age of the mangrove system ranged between 1000 and 5100 yr depending on the topographic elevation of the drilling location.

A review and technical summary of the AAPG Hedberg Research Conference “Variations in fluvial-deltaic and coastal reservoirs deposited in tropical environments”

This conference addressed the question of whether fluvial-deltaic and coastal reservoirs deposited in tropical environments exhibit different facies relationships than those of temperate systems. Although this conference concluded that there is nothing distinctly unique about clastic depositional systems in tropical environments, the magnitude of the processes that operate in these environments differs from nontropical environments. Because these processes influence the distribution of reservoir and nonreservoir facies, geologists need a fundamental understanding of the contrasts between tropical and nontropical environments when interpreting subsurface data and building depositional models. We highlight the following features that seem to be more favorably developed in tropical environments. (1) Many tropical systems exhibit complexly stacked channel and overbank deposits. Although some fluvial deposits have the classic meandering pattern, seismic attributes indicate that many tropical channel belts are anastomosing systems that intersect each other at large angles. Subsurface correlation without the benefit of three-dimensional seismic data is all but impossible. (2) In contrast to deltaic deposits in temperate climates, which exhibit high sand/shale ratios near the delta with sand content decreasing basinward and laterally away from the delta, tropical deltas tend to be muddier near the river mouth and have cleaner, well-sorted sand bodies better developed laterally in the shoreface and shallow-marine environments. (3) Modern tropical coasts are home to large estuarine environments dominated by mangroves. Estuarine deposits interpreted in the subsurface and observed in outcrop are sand rich, yet little sand is observed in modern mangrove estuaries. Mangrove estuarine deposits also contain abundant organic-rich layers, thin coals, and dispersed organic matter that may favor the development of a self-sourced petroleum system. The flushing of these systems during relative low stands may be an important mechanism not only for reservoir development, but also for dispersing organic matter into deep-water systems. This conference was dominated by discussions of depositional systems in Southeast Asia, which have a strong tectonic overprint. Further research on tropical systems from the South American and African conjugate margin could provide important tests for the ideas highlighted above.

Whither shore platforms?

This paper reviews the research on shore platforms since 1980. Although some quantitative work on platforms was conducted in the late 1970s, it was principally in the 1980s that there was a change in the research paradigm, from qualitative observations to quantitative analyses. Researchers are now closer than ever before on agreeing that no single process can produce shore platforms in itself. The last decade has seen remarkable proliferation of research interests in shore platforms. Consequently, there are much-improved data sets on the processes acting on them. Even so, it has not yet been possible to establish definitively the precise role of each individual process in shore platform evolution. Laboratory simulation of platform morphodynamics has received much less attention compared to field-based studies. There are also some other aspects, such as threshold determination, geological control, inheritance, application of geo-informatics and focus on low-energy and tropical coasts, that have received limited attention. These areas are avenues for future research. To enable a better understanding of platform dynamics in a particular area, fieldwork, laboratory simulation and numerical modelling should be carried out simultaneously. Shore platforms are a global feature, and their study should be undertaken in all parts of the world through increased collaborative work among researchers.

Is the trace fossil Macaronichnus an indicator of temperate to cold waters? Exploring the paradox of its occurrence in tropical coasts

The trace fossil Macaronichnus is reported for the first time from low-latitude, tropical settings based on its occurrence in nearshore deposits in the Upper Oligocene–Lower Miocene Naricual Formation and in the Middle to Upper Miocene Urumaco Formation in northern Venezuela. Macaronichnus is an intrastratal trace fossil attributed to the deposit-feeding of worms in high-energy, sandy shallow-marine environments. The majority of its occurrences are from Mesozoic to Cenozoic high- to intermediate-latitude shorelines. The opheliid polychaetes Ophelia limacina and Euzonus mucronata make structures identical to those described from the fossil record in modern intertidal and shallow subtidal sediments of northwestern United States, western Canada, and Japan. Macaronichnus shows a geographical and environmental distribution in the fossil record similar to that of its modern producers and has been proposed as an indicator of high to intermediate latitudes. Accordingly, its presence in the Neogene of Venezuela is highly anomalous and seems to challenge its paleoclimatic value. However, this occurrence may be related to seasonal coastal upwelling of nutrient-rich cold waters. Such oceanographic conditions were prevalent in the northern coast of South America, at least from the Late Oligocene to the Early Pliocene prior to the final closure of the strait of Panama. This study underscores the value of Macaronichnus because its presence in the tropics may indicate upwelling conditions, providing high-resolution information in paleoceanographic reconstructions.

Biocomplexity in Mangrove Ecosystems

Mangroves are an ecological assemblage of trees and shrubs adapted to grow in intertidal environments along tropical coasts. Despite repeated demonstration of their economic and societal value, more than 50% of the world's mangroves have been destroyed, 35% in the past two decades to aquaculture and coastal development, altered hydrology, sea-level rise, and nutrient overenrichment. Variations in the structure and function of mangrove ecosystems have generally been described solely on the basis of a hierarchical classification of the physical characteristics of the intertidal environment, including climate, geomorphology, topography, and hydrology. Here, we use the concept of emergent properties at multiple levels within a hierarchical framework to review how the interplay between specialized adaptations and extreme trait plasticity that characterizes mangroves and intertidal environments gives rise to the biocomplexity that distinguishes mangrove ecosystems. The traits that allow mangroves to tolerate variable salinity, flooding, and nutrient availability influence ecosystem processes and ultimately the services they provide. We conclude that an integrated research strategy using emergent properties in empirical and theoretical studies provides a holistic approach for understanding and managing mangrove ecosystems.

Monitoring wetlands deterioration in the Cameroon coastal lowlands: implications for management

The problems of coastal wetlands hazards and management are increasingly apparent in the face of rapid population growth in coastal zones worldwide. This has significantly heightened scientific interest in spatio-temporal analysis of the Global Environmental Change (GEC) effects in the coastal zones, particularly of the sandy, swampy depositional coastal environment characteristic of the humid tropical coasts. Evolved with massive sedimentation of the Holocene period which saw the drowning of the mouths of coastal rivers along the humid tropical coastlines, the Cameroon costal lowlands of interest in this paper describes extensive wetlands from the Limbe area to the west and the Douala area to the east, which today is characterized by a lagoon system. This locality is easily the most rapidly urbanized area in Cameroon witnessing extensive spatial expansion in the Limbe, Tiko and Douala areas, which has provoked certain observable environmental problems with the conversion of the wetlands, The area now suffer in form of poor land reclamation practices, highway construction, impaired water quality, dismal domestic sewage disposal, heavy effluent discharge, subsidence etc. This paper utilizes the opportunity offered by remote sensing tools to monitor the wetlands over space and time to cover regional and micro scales. SLAR (Side Looking Airborne Radar) imagery permits quick and accurate mapping of coastline detail, while coverage of changing patterns of features over space and time is enhanced for management implications.