POPULATION STRUCTURE AND PHYSIOLOGICAL DIFFERENTIATION OF HAPLOTYPES OF CALOGLOSSA LEPRIEURII (RHODOPHYTA) IN A MANGROVE INTERTIDAL ZONE

Zonation of macroalgae in the intertidal zone has been well documented. However, studies of zonation of macroalgae have predominantly examined the distribution of different species rather than the distribution of variants within a species. This study investigated the spatial variation of plastid haplotypes of the mangrove red alga Caloglossa leprieurii (Montagne) J. Agardh at a site in eastern Australia and tests for physiological differences (growth, photosynthesis) between those haplotypes. RUBISCO spacer plastid haplotypes were scored using single-stranded comformational polymorphism, and the population structure at two sites was examined using a nested sampling design comparing between sites, among transects within sites, and among quadrats within transects. Growth rates at various salinities and light intensities and the photosynthesis–irradiance curves of the three main haplotypes were compared. The two sites showed a high degree of genetic differentiation across a short distance, suggesting limited gene flow. The distribution of haplotypes was patchy and did not reflect a zonation pattern along the intertidal gradient. The three haplotypes were physiologically differentiated with haplotype A, with a lower growth rate and a lower photosynthetic efficiency at higher light intensities. There is some evidence of physiological differentiation between life history phases in C. leprieurii with sporophytes having a higher growth rate than females under most conditions. Our results suggest a correlation between our culture results and our population data. Haplotypes (haplotype A) and life history phases (gametophytes) with lower performance (growth and photosynthetic efficiency) under our culture conditions were correlated with a minor representation in the field. This is the first study to integrate population-level data with physiological parameters toward an understanding of the distribution and relative abundance of red algal genetic variants.     

Habitats of Culicoides spp. in an intertidal zone of southeast Queensland, Australia

The distribution of immature Culicoides Latreille (Diptera: Ceratopogonidae) in the intertidal zone was investigated at Redland Bay near Brisbane, southeast Queensland. The aims of this study were to determine the distribution of Culicoides immatures and to identify environmental factors influencing these distributions. Light trapping of adult midges indicated that C.subimmaculatus Lee & Reye, C.marmoratus (Skuse), C.longior Hagan & Reye, C.henryi Lee & Reye, C.cordiger Macfie, may have been breeding in the study site. Soil sampling on six transects traversing mangrove and salt-marsh revealed the breeding habitats from which immature stages of the first four species were obtained. The elevation, vegetation and soils of positive sites were recorded and analysed for each species of Culicoides. The distribution of intertidal vegetation (mangroves and salt-marsh plants) was compared to MacNae's (1966) system of mangrove zonation for eastern Australia. The distribution of immature Culicoides did not correspond with mangrove zones, but was related to the presence or absence of intertidal vegetation. C.subimmaculatus was closely associated with a particular substrate and the presence of burrowing crabs.     

Species-area relationship and potential role as a biomonitor of mangrove communities of Malayan mudskippers

The rapid and extensive destruction of mangrove forests and adjacent peritidal ecosystems in the Indo-Pacific region requires the development of efficient management and conservation actions. Mudskippers (Gobiidae: Oxudercinae) are amphibious gobies that are strictly linked to mangrove forests and tropical mudflats. I recorded the presence and habitat distribution of mudskipper species in four mangrove ecosystems along the west coast of Peninsular Malaysia. Different localities host different mudskipper communities, while in each locality species are differentially distributed along the intertidal gradient. At the ecosystem level, I found a significant exponential correlation between sampled area and the species richness of these communities, consistent with the SAR hypothesis. At the habitat level, the presence of a vertical zonation along the intertidal gradient suggests the possibility of using the species living exclusively in higher or lower levels as bioindicators for habitat anthropogenic impact, respectively from the land and from the sea.     

Dynamics of sediment carbon stocks across intertidal wetland habitats of Moreton Bay,Australia

Coastal wetlands are known for high carbon storage within their sediments, but our understanding of the variation in carbon storage among intertidal habitats, particularly over geomorphological settings and along elevation gradients, is limited. Here, we collected 352 cores from 18 sites across Moreton Bay, Australia. We assessed variation in sediment organic carbon (OC) stocks among different geomorphological settings (wetlands within riverine settings along with those with reduced riverine influence located on tide‐dominated sand islands), across elevation gradients, with distance from shore and among habitat and vegetation types. We used mid‐infrared (MIR) spectroscopy combined with analytical data and partial least squares regression to quantify the carbon content of ~2500 sediment samples and provide fine‐scale spatial coverage of sediment OC stocks to 150 cm depth. We found sites in river deltas had larger OC stocks (175–504 Mg/ha) than those in nonriverine settings (44–271 Mg/ha). Variation in OC stocks among nonriverine sites was high in comparison with riverine and mixed geomorphic settings, with sites closer to riverine outflow from the east and south of Moreton Bay having higher stocks than those located on the sand islands in the northwest of the bay. Sediment OC stocks increased with elevation within nonriverine settings, but not in riverine geomorphic settings. Sediment OC stocks did not differ between mangrove and saltmarsh habitats. OC stocks did, however, differ between dominant species across the research area and within geomorphic settings. At the landscape scale, the coastal wetlands of the South East Queensland catchments (17,792 ha) are comprised of approximately 4,100,000–5,200,000 Mg of sediment OC. Comparatively high variation in OC storage between riverine and nonriverine geomorphic settings indicates that the availability of mineral sediments and terrestrial derived OC may exert a strong influence over OC storage potential across intertidal wetland systems.     

Patterns of Species Number and Abundance in Macroalgal Communities in Coastal Waters

Predictable patterns of species number have been observed in relation to habitat size, habitat heterogeneity and environmental conditions, while patterns in relative abundance of species have been examined for few communities and no assembly rules have been established. We studied communities of attached macroalgae in 61 individual sites located in four different areas; the inner, middle and outer parts of three neighbouring low-tidal estuaries and the adjacent open waters of the Kattegat, Denmark. The objectives were to determine (1) the relationships of species number and rank-abundance to the environmental conditions, and (2) the importance of scale and the consistency of species rank number at the sites for these relationships. We found that species number increased significantly from the inner estuaries to the open coastal waters along with decreasing nutrient concentrations. Turnover (β) diversity was lowest in the open waters suggesting that species composition was more similar among samples there than in the estuaries. Rank-abundance curves did not differ between depth intervals and individual sites across the environmental gradients. However, the summed rank-abundance patterns for two sites showed significantly steeper initial slopes and dominance of few species (i.e., low evenness) in the inner estuaries than in open waters. This pattern was due to high rank consistency of dominant species among sites in the inner estuaries. In open waters rank consistency was low, and the summed abundance across sites showed an even abundance of species. The results imply that the scale of the study and the community variability observed at that particular scale, is the main determinant of abundance patterns.     

Spatial and temporal variability of early post-settlement survivorship and growth in the barnacle Balanus glandula along an estuarine gradient

The performance of a species can be significantly altered by subtle changes in the physical environmental. The intertidal barnacle Balanus glandula is predominantly an open coast species in the Northeast Pacific. However, B. glandula commonly inhabits estuaries where environmental conditions such as salinity and temperature drastically differ from the open coast. We used survivorship and growth rates as a measure of performance in recently metamorphosed laboratory reared juvenile B. glandula outplanted along an environmental gradient at the mouth, mid-estuarine, and riverine end of the South Slough Estuary, Oregon, USA. Juvenile performance was highly variable over spatial and temporal scales and dependent upon existing environmental conditions. Surprisingly, along this estuarine gradient, juveniles performed better at a mid-estuarine location than at the mouth of the estuary. Typically, the riverine end of the estuary was the least suitable habitat along the estuarine gradient due to high juvenile mortality and a low growth rate. Although seasonally variable, survivorship and growth decreased with height along a vertical intertidal gradient as well. In a reciprocal transplant experiment, populations from both ends of the estuarine gradient displayed similar survivorship and growth rates. Our results demonstrate that the interactions of environmental conditions that vary temporally and spatially along a gradient strongly affect the success of an individual surviving and prospering during the early juvenile period.     

Causes and consequences of thermal tolerance limits in rocky intertidal porcelain crabs, genus petrolisthes

Vertical zonation of intertidal organisms, from the shallowsubtidal to the supralittoral zones, is a ubiquitous featureof temperate and tropical rocky shores. Organisms that livehigher on the shore experience larger daily and seasonal fluctuationsin microhabitat conditions, due to their greater exposure toterrestrial conditions during emersion. Comparative analysesof the adaptive linkage between physiological tolerance limitsand vertical distribution are the most powerful when the studyspecies are closely related and occur in discrete vertical zonesthroughout the intertidal range. Here, I summarize work on thephysiological tolerance limits of rocky intertidal zone porcelaincrab species of the genus Petrolisthes to emersion-related heatstress. In the eastern Pacific, Petrolisthes species live throughouttemperate and tropical regions, and are found in discrete verticalintertidal zones in each region. Whole organism thermal tolerancelimits of Petrolisthes species, and thermal limits of heartand nerve function reflect microhabitat conditions. Speciesliving higher in the intertidal zone are more eurythermal thanlow-intertidal congeners, tropical species have the highestthermal limits, and the differences in thermal tolerance betweenlow- and high-intertidal species is greatest for temperate crabs.Acclimation of thermal limits of high-intertidal species isrestricted as compared to low-intertidal species. Thus, becausethermal limits of high-intertidal species are near current habitattemperature maxima, global warming could most strongly impactintertidal species.     

Intertidal zonation and latitudinal gradients on macroalgal assemblages: Species,functional groups and thallus morphology approaches

Macroalgae are unavoidable biological elements when monitoring and assessing costal environments. However, these tasks can be difficult to address because macroalgae a) present a high natural variability across a range of spatial and temporal scales, b) they imply a high sampling and laboratory processing effort and good taxonomical expertise (as they are a very diverse group of species), and c) there is insufficient knowledge about their structural and functional characteristics. This work addressed how the vertical (intertidal zonation) and horizontal (latitudinal gradient) variability of macroalgae assemblages are structured across continental Portugal, as well as how some surrogates for species-level biodiversity measures (namely functional groups and thallus morphology approaches) respond to such large-scale variability. Particularly, it was tested if intertidal zonation patterns are higher than fine-scale horizontal variation, and however, if vertical variation decreases along broad-scale horizontal variation. To do so, cover per species was taken (using a photographical and GIS methodological approach) from five sites located along the shoreline and along respective upper- mid- and lower-intertidal zones. The work findings include that both intertidal and latitudinal gradients impose deep structural changes on assemblages patterns. That is, broad-scale processes along Portuguese latitudes act as strongly as vertical stress gradients on assemblages patterns. Functional groups and thallus morphology approaches were useful to generalize the latitudinal assemblages patterns, where some groups emerge at the expense of others, and may improve biodiversity understanding and ecological synthesis. Because these surrogates decrease taxonomical expertise needs and can provide insight into the functional structure of macroalgal communities, their patterns founded may be particularly useful as reference data for further monitoring, so that shifts in such patterns might represent early warning surrogate approaches to detect environmental impact changes. Ultimately, to generate broader databases on rocky shore assemblages diversity (from species-level to functional groups and thallus morphologies approaches) can be useful for large-scale comparisons and for establishing ecological reference conditions, including for monitoring programs and environmental impact studies.     

The distribution and state of mangroves along the coast of Transkei,Eastern Cape Province,South Africa

The mangrove communities along the coastline of the former Transkei, now part of the Eastern Cape Province, have not been looked at in detail since Ward and Steinkes survey in 1982. Mangroves previously occurred in 17 estuaries but were now found in only 14 of the 76 estuaries visited, with a complete loss of mangroves evident in the Mnyameni, Mzimvubu and Bulungula estuaries amounting to 7.5 ha. Total mangrove loss amounted to 17.6 ha which represents a 6.5% loss over 17 years or 1.04 ha per annum. Tree cover had increased by 16.15 ha in eight other estuaries. This increase could be attributed to the inaccessibility of mangrove stands or to protection afforded by provincial nature reserves and hotel resorts. No new mangrove stands were recorded, although Steinke (pers. comm.) has recently recorded mangroves along the north bank of the Kei River. There has been little change in mangrove species composition in the different estuaries over the past 17 years. Total mangrove loss amounted to 17.6 ha which represents a 6.5% loss over 17 years or 1.04 ha per annum and the species recorded included Avicennia marina, Bruguiera gymnorhiza and Rhizophora mucronata. The mangrove fern Acrostichum aureum L. was recorded for the first time in the Mkozi estuary. Tree density for all estuaries was between 10 and 2594 trees ha^–1. The Mngazana and Mntafufu estuaries had the highest tree densities of 2594 and 1402 trees ha^–1 respectively, typical of riverine mangrove forests. Fringe mangroves were evident in most other systems. Removal of trees for wood has the greatest impact on mangrove cover. Fringe mangrove stands are particularly accessible to harvesters. Only 6% of the current area of trees is afforded some protection in conservation areas. The Mdumbi, Mzamba and Kobonqaba estuaries receive no conservation protection and harvesting has resulted in more than 50% of the trees being removed. The density of dead tree stumps was greater than the number of living trees and no seedlings or juvenile trees were found. Further removal of mangroves within the estuaries south of the Mzimvubu River is expected in the fringe mangroves, as most are unprotected and easily accessible.     

Assessment of the diversity and abundance of terrestrial mangrove arthropods in southern New South Wales,Australia

Abstract The diversity and abundance of arboreal and flying arthropods, in three mangrove patches along the south coast of New South Wales, Australia, was investigated to determine the degree of spatial variability in the assemblages among patches. Intercept traps and restricted canopy fogging were used to sample the communities at Minnamurra, Bonnievale and Kurnell. Twelve orders of arthropods were detected, incorporating 252 morphospecies. Abundance, species richness and species composition were very similar across all patches, the variation being much smaller than expected. These findings suggest that the composition of the arboreal and flying fauna associated with mangrove patches are very similar among patches, but preliminary results also showed that species composition could be highly variable within a patch. Variation between the trapping methods was large, as expected . Intercept trapping and restricted canopy fogging techniques were found to sample different suites of species and therefore complement each other well in sampling programs. Cumulative species curves differed between time periods but generally were flatter for intercept traps than for restricted canopy fogging. Results suggested, for a given level of effort, intercept traps caught a more representative sample of the species composition available to them.     

The spatial and vertical distribution of living (stained) benthic foraminifera from a tropical,intertidal environment,north Queensland,Australia

We investigated the distribution of living (stained) benthic foraminifera across a tropical, intertidal shoreline adjacent to Cocoa Creek, Queensland, Australia for the purpose of better understanding the nature of test production and ultimately fossil assemblage development within such environments. Short cores (up to 1 m) were collected during the wet and dry season, along an elevational gradient comprising non-vegetated intertidal mudflat and higher-intertidal mangrove forest environments. The distribution of stained specimens can be broadly delineated into assemblages characterising ‘upper mangrove’ (2.64–2.91 m above Lowest Astronomical Tide (LAT)) and ‘low mangrove-mudflat’ (1.62–2.18 m above LAT) environments. Agglutinated species were generally limited to upper mangrove stations. Calcareous species occurred within all of the intertidal environments examined but differ in their composition between upper and lower intertidal settings. Upper mangrove faunas were characterised by the agglutinated species Arenoparrella mexicana, Haplophragmoides wilberti, Miliammina fusca, Miliammina obliqua and Trochammina inflata and the calcareous species Helenina anderseni. Live (stained) assemblages at lower intertidal elevations were dominated by the calcareous species Ammonia aoteana, as well as Rosalina spp., Elphidium oceanicum, Triloculina oblonga, Ammonia pustulosa and Shackoinella globosa.     

The influence of mangrove-derived tannins on intertidal meiobenthos in tropical estuaries

Summary Mangrove-derived tannins negatively effected laboratory-reared nematode populations and natural communities of meiobenthos in tropical mangrove forests along the northeastern coast of Australia. In the low and mid intertidal zones of five mangrove estuaries, nearly all of the dominant meiofaunal taxa correlated negatively with concentrations of sediment tannins. Only nematodes correlated with low tannin concentrations in the high intertidal zones. The negative exponential equation y=be ^-mx represented the best-fit for most of the meiofauna-tannin relationships. The mangrove-dwelling nematode, Terschellingia longicaudata did not grow (r=0.001) in the laboratory on fresh, tannin-rich leaves of the red mangrove, Rhizophora stylosa. Population growth of the nematode was significantly greater on fresh, tannin-poor leaves of the grey mangrove, Avicennia marina (r=0.081) with best growth (r=0.112) attained on a diet of tannin-free, mixed cereal. These preliminary field and laboratory results suggest that hydrolyzable tannins leached from mangrove roots and leaf litter are an important factor regulating intertidal meiobenthic communities in tropical mangrove forests along the northeastern Australian coast.     

Ecological Genetics of Mpi and Gpi Polymorphisms in the Acorn Barnacle and the Spatial Scale of Neutral and Non-neutral Variation

Different allozyme genotypes at the mannose phosphate isomerase(Mpi) locus in the northern acorn barnacle (Semibalanus balanoides)show a strong association with distinct intertidal microhabitats.In estuaries along the Maine Coast, the FF homozygote has higherfitness in exposed, high-tide level microhabitats while theSS homozygote has higher fitness under algal cover or at low-tidemicrohabitats. These patterns are consistent with a Levene (1953)model of balancing selection. In these same samples, polymorphismsat the glucose phosphate isomerase locus (Gpi) and mitochondrialDNA (mtDNA) show no fitness differences among microhabitats,providing intra-genomic controls supporting selection at ornear Mpi. Here we report a similar analysis of genotype-by-microhabitatassociations at sites in Narragansett Bay, Rhode Island, closeto the southern range limit of S. balanoides. Genotype zonationat Mpi between high- and low-tide microhabitats is significantlydifferent between Maine and Narragansett Bay due to oppositezonation patterns for the SF and FF genotypes. Enzyme activitydata are consistent with this "reverse" zonation. At Gpi, thereis significant microhabitat zonation in Narragansett Bay, whilethis locus behaves as a neutral marker in Maine. Mt DNA showsno significant microhabitat zonation in either Rhode Islandor Maine. The Mpi data suggest that Levene-type selection foralternative genotypes in alternative habitats may operate atscales of both 10's of meters and 100's of kilometers. The Gpidata show how an apparently neutral locus can exhibit non-neutralvariation under different environmental conditions. We arguethat both Mpi and Gpi provide important genetic variation foradaptation to environmental heterogeneity that is recruitedunder distinct conditions of stress and carbohydrate substrateavailability.     

Zonation of intertidal macrobenthos in the estuaries of Schelde and Ems

Based on data, collected in 1980–1990, the intertidal benthic macrofauna of the Schelde and Ems estuaries was compared. The spatial occurrence of the benthic macrofauna along the salinity gradient, including the freshwater tidal area was emphasized. Both estuaries appeared to have a very similar species composition, especially at genus level. The higher number of species observed in the Schelde estuary was probably due to a greater habitat diversity. In both estuaries species diversity decreased with distance upstream. The total density did not vary along the estuarine gradient, whereas biomass is highest in the polyhaline zone.In both estuaries distinct intertidal benthic communities were observed along the salinity gradient: a marine community in the polyhaline zone, a brackish community in the mesohaline zone, and a third community in the oligohaline and freshwater tidal zones of the estuary. These three communities were very similar between both estuaries. Their main characteristics were discussed together with the occurrence and distribution of the dominant species.For the Schelde estuary and to a lesser extent also for the Ems estuary, there was evidence that anthropogenic stress had a negative effect on the intertidal macrobenthic communities of the oligohaline/freshwater tidal zone. Only Oligochaeta were dominating, whereas the very euryhaline and/or true limnetic species were missing. In the mesohaline zone, the Schelde estuary was dominated by large numbers of short-living, opportunistic species, whereas in the Ems estuary relatively more stable macrobenthic communities were observed. A comparison with some other European estuaries showed in general similar trends as those observed for the Schelde and Ems estuaries.     

Meiobenthic distribution and nematode community structure in five European estuaries

Meiofauna from the intertidal zone of five European estuaries (Ems, Westerschelde, Somme, Gironde, Tagus) was investigated. Samples represented a cross section of various benthic habitats from near-freshwater to marine, from pure silts to fine-sandy bottoms. The meiobenthic community comprised everywhere a fauna strongly dominated by nematodes, with meiobenthic density increasing with increasing salinity. The Ems differed from the other estuaries due to the presence of a well developed community of Copepods, Gastrotrichs, large Ciliates and/or soft-shelled Foraminiferans in some sites. The Westerschelde stood out due to the near-absence of harpacticoid copepods and, as in the Tagus, the lower meiobenthic densities in the marine part of the estuary. For nematode community analysis, we also included data from the Tamar which were obtained from the literature (Warwick &; Gee, 1984). This resulted in the enumeration of 220 species, belonging to 102 genera, each with a characteristic distribution along the salinity, sedimentary and latitudinal gradients. Using the multivariate technique CANOCO, a zonation along these different physicochemical determinants was observed as well although salinity and sediment characteristic (scale of hundreds of meters to kilometers) proved to be more important in explaining community structure than latitudinal differences (scale of hundreds of kilometers). Nematode diversity was nearly entirely determined on the genus level and was positively related to salinity. Deviations from this general trend in the Gironde and the Tamar were attributed to sedimentary characteristics or to low macrobenthic predation. The presence of a typical opportunistic colonizing nematode species Pareurodiplogaster pararmatus in the low-salinity region of the Gironde could indicate (organic?) pollution or disturbance of the intertidal mud-flats.     

Palynomorph distribution in a mangrove ecosystem along environmental and salinity gradient: a tool for palaeoecological reconstruction

Pollen assemblages closely reflect the local vegetation that characterizes the salinity status, providing useful analogs for paleoecologxical reconstruction in regional deposits. Palynological evidences of surface sediments from the Coringa mangrove wetland were correlated with the physicochemical and sediment salinity records to observe the relationship between them. The statistical analysis of the data obtained here revealed a marked horizontal salinity gradient from north to south.. In this study, ordination (detrended correspondence analysis) of palynomorph groups has identified a salinity gradient of 1.1 to 3.0 PSU from the north to the south in the wetland. High palynomorph deposition and lower salinity are observed along channel margins due to the mixing of estuarine water during the rainy season. The mudflats along the transects show a lower diversity of plants in the pollen record and high total dissolved solids (TDS) than commonly found in the coastal wetlands. The presence of scrubby halophytic vegetation in the upper saltmarsh and oligohaline-freshwater vegetation in the low tidal saline marshes is a zonation pattern related to the localized influence of freshwater conditions. Palynomarine Index (PMI) reveals the highest freshwater/tidal inundation along Ramannapalem due to the presence of numerous riverine channels while the remaining part of the wetland has restricted tidal inundation leading to the conversion of mangrove forests to salt pans and paddy fields. Thus, the health and productivity of the mangrove ecosystem are also governed by hydrodynamics, catchment land use, water discharge in the channels, and tidal flushing.

     

Predicting changes in molluscan spatial distributions in mangrove forests in response to sea level rise

Mollusks are an important component of the mangrove ecosystem, and the vertical distributions of molluscan species in this ecosystem are primarily dictated by tidal inundation. Thus, sea level rise (SLR) may have profound effects on mangrove mollusk communities. Here, we used dynamic empirical models, based on measurements of surface elevation change, sediment accretion, and molluscan zonation patterns, to predict changes in molluscan spatial distributions in response to different sea level rise rates in the mangrove forests of Zhenzhu Bay (Guangxi, China). The change in surface elevation was 4.76–9.61 mm year⁻¹ during the study period (2016–2020), and the magnitude of surface‐elevation change decreased exponentially as original surface elevation increased. Based on our model results, we predicted that mangrove mollusks might successfully adapt to a low rate of SLR (2.00–4.57 mm year⁻¹) by 2100, with mollusks moving seaward and those in the lower intertidal zones expanding into newly available zones. However, as SLR rate increased (4.57–8.14 mm year⁻¹), our models predicted that surface elevations would decrease beginning in the high intertidal zones and gradually spread to the low intertidal zones. Finally, at high rates of SLR (8.14–16.00 mm year⁻¹), surface elevations were predicted to decrease across the elevation gradient, with mollusks moving landward and species in higher intertidal zones blocked by landward barriers. Tidal inundation and the consequent increases in interspecific competition and predation pressure were predicted to threaten the survival of many molluscan groups in higher intertidal zones, especially arboreal and infaunal mollusks at the landward edge of the mangroves, resulting in a substantial reduction in the abundance of original species on the landward edge. Thus, future efforts to conserve mangrove floral and faunal diversity should prioritize species restricted to landward mangrove areas and protect potential species habitats.     

Multiple markers pyrosequencing reveals highly diverse and host-specific fungal communities on the mangrove trees Avicennia marina and Rhizophora stylosa

Fungi are important actors in ecological processes and trophic webs in mangroves. Although saprophytic fungi occurring in the intertidal part of mangrove have been well studied, little is known about the diversity and structure of the fungal communities in this ecosystem or about the importance of functional groups like pathogens and mutualists. Using tag-encoded 454 pyrosequencing of the ITS1, ITS2, nu-ssu-V5 and nu-ssu-V7 regions, we studied and compared the fungal communities found on the marine and aerial parts of Avicennia marina and Rhizophora stylosa trees in a mangrove in New Caledonia. A total of 209,544 reads were analysed, corresponding to several thousand molecular operational taxonomic units (OTU). There is a marked zonation in the species distribution, with most of the OTU being found specifically in one of the microhabitat studied. Ascomycetes are the dominant phylum (82%), Basidiomycetes are very rare (3%), and 15% of the sequences correspond to unknown taxa. Our results indicate that host specificity is a key factor in the distribution of the highly diverse fungal communities, in both the aerial and intertidal parts of the trees. This study also validates the usefulness of multiple markers in tag-encoded pyrosequencing to consolidate and refine the assessment of the taxonomic diversity.     

Heterogeneity in intertidal fish fauna assemblages along the world's longest mangrove area in northern Brazil

The first comparison of the intertidal fish fauna from three estuaries within the longest contiguous mangrove area of the world, in north Brazil, revealed a significant heterogeneity in the species composition and functional and ecological guilds with an increase of Tetraodontidae and Engraulidae and a decrease of Sciaenidae and Mugilidae towards the Amazon mouth. A classification of the mangrove estuaries to identify types of estuaries and coastal sectors is urgently required to provide a tool for regional management systems in order to improve research, monitoring and conservation of this unique mangrove ecosystem.     

Mangrove distribution in Northwestern Australia in relationship to regional and local freshwater seepage

The regional distribution of mangrove species along the tropical NW coast of Australia is closely related to climate. In subhumid regions with rainfall >1000 mm/yr mangals have 12 species which are recurring and common. The climate becomes more arid southwards and species richness decreases: 8 species are common in mangals in semiarid regions and 5 species are common in arid regions. Rainfall influences the distribution of species across tidal flats because of direct recharge to groundwater systems and also because of subsurface seepage along the hinterland edge. Much of the increase in species diversity is located along high parts of tidal flats and along the edge of the hinterland. At the local level stratigraphy forms an important part of the hydrology by determining the distribution of aquifers and aquacludes. Fresh water seeps into the tidal lands via buried, discrete aquifers and dilutes the highly hypersaline groundwater. Mangroves inhabit these local areas above the less saline groundwater. The influence of rainfall and freshwater seepage on mangals is presented as a unifying theme which helps to explain distribution and diversity of mangroves at both a regional and local level.