Substrate type and microbial interactions as factors affecting ascocarp formation by mangrove fungi

The growth and ascocarp formation of Aigialus parvus, Lignincola laevis and Verruculina enalia in single and mixed cultures on wood of Avicennia alba, Bruguiera cylindrica and Rhizophora apiculata was studied. In pure cultures, these fungi grew well on all three species of wood. Except for Aigialus parvus on B. cylindrica, all three fungi also formed abundant ascocarps. The time needed for ascocarp formation after inoculation ranged from six to eight weeks for L. laevis on all wood species, and for V. enalia on Avicennia alba; to ten weeks for V. enalia on B. cylindrica and R. apiculata; and 12 weeks for Aigialus parvus on Avicennia alba and R. apiculata.Mixed cultures involving two or three of the test fungi delayed the onset of sporulation and affected the abundance of ascocarps formed. Sporulation by Aigialus parvus on Avicennia alba and R. apiculata was markedly reduced by L. laevis alone or in combination with V. enalia. Likewise, sporulation by L. laevis was suppressed by Aigialus parvus and/or V. enalia. In contrast, the presence of L. laevis enhanced ascocarp formation by V. enalia on all types of wood. These observations suggest the presence of interference competition among the test fungi.     

Effects of mangrove soil ageing on the accumulation of hydrogen sulphide in roots ofAvicennia spp

The possibility for accumulation of hydrogen sulphide gas in roots of mangroves (Avicennia spp) which had colonized reclaimed coastal areas in Singapore was investigated using a simple potentiometric technique preceded by an extraction step. The study showed that detectable amounts of hydrogen sulphide gas were present in the underground cable roots of the mangroves and that the concentrations increased with the age of the plant. Furthermore concentrations of hydrogen sulphide in the roots were 30–40 times higher than the concentrations of the gas which were simultaneously generated by anaerobic processes in the surrounding, ageing mangrove sediment. The reasons for these patterns and their possible impact on the succession ofAvicennia spp by a different type of mangrove,Rhizophora spp, are discussed.Author to whom correspondence should be addressed     

Recovery Deficiency Following Tree Mortality in Mangroves of Two Caribbean Islands: Field Survey and Statistical Classification

Mangrove species are well adapted to the harsh ecological conditions of their environment throughout the tropics. However, in the islands of Guadeloupe and Martinique (Lesser Antilles), deficient forest recovery was evidenced in 43 mangrove sites (>1000 m²) affected by apparently natural tree mortality. Such sites were recorded from four chronological sets of aerial photographs between 1950 and 1995, and field-investigated in terms of environment and vegetation characteristics. Given the speculative relationship between the slow-regenerating vegetation and its present environment within non-steady state, disturbed sites, statistical analyses arbitrarily matching physicochemical and biological data were primarily avoided. On one hand, principal component analysis (PCA), combined with an agglomerative hierarchical classification, was performed on environmental, rank-ordered data; on the other hand, multidimensional scaling (MDS) was implemented on vegetation data. Discriminant analyses (DA) further characterized the environment/vegetation interrelationships for each site type. Ultimately, three main types of mortality sites have been distinguished among the study areas. One type clustered the sites showing the lowest salinity values and the highest surge vulnerability whose dominant mangrove species is Rhizophora. Another type presented highly saline sites having clayey soils with pure, stunted, Avicennia stands. The last type consisted of peculiar forest gaps on deep, compact, peat soils. During the rainy season, these sites turned into shallow ponds scattered with living, young Rhizophora and large, standing, dead Avicennia. The authors suggest that this classification may serve as a comprehensive framework to test subsequent hypotheses (hurricanes, droughts…) on the origins of natural massive tree mortality and the causes of recovery deficiency in mangroves of the Caribbean.     

The abundance and growth of Avicennia marina and Rhizophora stylosa in the low shore zone of Darwin Harbour,Northern Territory

Abstract The growth and distribution of the two mangrove seedling species, Avicennia marina (Forsk.) Vierh. and Rhizophora stylosa Griff., were studied in the low-shore zone at three locations along two estuaries of Darwin Harbour to determine how growth varied along the estuary and within the habitats of the low shore zone. The low shore environment was heterogenous for factors such as salinity and light, with substantial variation within and between locations. Seedlings of Avicennia were in higher densities in light gaps than in the adjacent forest, and density in both habitats decreased towards the mouth of the estuary. Growth of Avicennia seedlings, as measured through in situ growth trials and plant harvests, increased towards the mouth of the estuary. Results for Rhizophora seedlings were more complex although some similar trends were evident. This may have been due to the greater early survival of Rhizophora seedlings compared to Avicennia seedlings. The importance of propagule origin was investigated, for Rhizophora, by transplanting propagules between locations along one estuary. Increased seedling survival was observed at the propagule source site; however, this effect was subtle and probably not the most important factor affecting seedling survival at a site.     

Seedling survivorship,growth, and response to disturbance in Belizean mangal

Species zonation patterns across tidal gradients in mangrove forests are formed by successful seedling establishment and maintained by replacement of adults by conspecific seedlings. These two processes rarely have been examined experimentally in neotropical mangal. We studied survivorship and growth of seedlings of two species of mangrove, Rhizophora mangle L. and Avicennia germinans (L.) Steam, across a tidal gradient in Belize, Central America. Propagules of each species were planted in common gardens at tidal elevations corresponding to lowest low water (LLW), mean water (MW), and highest high water (HHW). Sixty-nine percent of Rhizophora seedlings planted at MW and 56% of those planted at LLW survived 1 year. Forty-seven percent of MW Avicennia seedlings also survived 1 year. No individuals of either species survived at HHW, and neither did any LLW Avicennia seedlings. Among the surviving Rhizophora seedlings, LLW seedlings grew more rapidly in terms of height, diameter, leaf production, and biomass than did MW seedlings. Insect herbivory was twice as high on MW seedlings as on LLW Rhizophora seedlings. We also examined the response of established Rhizophora seedlings to experimental removal of the adult Rhizophora canopy. Seedlings in canopy removal areas had higher survivorship, grew twice as fast, produced more leaves, and had less than half the herbivory of seedlings growing beneath an intact canopy. These results provide insights into underlying causes and maintenance of zonation in Caribbean mangrove forests.     

Holocene mangrove dynamics and sea-level changes in northern Brazil, inferences from the Taperebal core in northeastern Pará State

A 450 cm sediment core from Taperebal, in the mangrove region of northeastern Pará State in northern Brazil has been studied through pollen analysis in order to reconstruct mangrove development and dynamics and to infer relative sea-level (RSL) changes during the Holocene. Six AMS radiocarbon dates, which provide a somewhat limited age control with some uncertainties, suggest early and late Holocene deposits interrupted by a hiatus between them. A patchy vegetation of coastal Amazon rain forest, restinga, salt marsh and some mangrove, which was dominated by Avicennia, covered the study area during the early Holocene period. The occurrence of an early Avicennia dominated mangrove phase has not been reported so far from other sites in northern Brazil. During the mid Holocene mangroves mostly replaced the former coastal Amazon rain forest, restinga and some salt marsh vegetation, reflecting the rise in the RSL. Rhizophora trees expanded markedly and Avicennia became rare. In the sediment core there is apparently a gap between the depths of 115 and 85 cm (possibly starting between 5900 and 5750 b.p.). The deposits above 85 cm are of modern age and were probably deposited during the last decades. This gap can be explained by the lowering of the RSL as is shown for other northern Brazilian coastal sites. The deposition of sediments during the last decades suggests that the modern RSL is high compared to other periods in the Holocene. Pollen data from these deposits show that Rhizophora trees dominate the mangrove forests, also indicating a high RSL.     

Occurrence and colonization of nematophagous fungi in different substrates,agricultural soils and root galls

Seventeen species of nematophagous fungi were recorded, three species were endoparasitic and fourteen species were predacious fungi. Among the predacious fungi Arthrobotrys oligospora, Dactylaria brochopaga and Monacrosporium eudermatum were very frequent, whereas others were recorded at lower frequency. Twelve species of nematophagous fungi from compost as well as cow dung manure, 15 species from leaf litter and only eight species from agricultural soils were recorded. In general, substrate colonization by nematophagous fungi was higher in leaf litter, compost and cow dung manure. The agricultural soil amended with FYM (farm yard manure) recorded nine species of nematophagous fungi while unamended soil recorded only seven species. Thirteen species of nematophagous fungi were recorded from soils under banyan tree. Of all these fungi unidentified net-forming fungus, M. eudermatum, A. cladodes, D. brochopaga, S. hadra, A. oligospora and A. dactyloides had higher percentage of soil colonization. In soil collected under pipal tree only eight species were recorded, of which A. oligospora, A. cladode and an unidentified fungus were more predominant as their percentage colonized in soil samples was higher. Few studies have examined root galls as a substratum for colonization of nematophagous fungi. Of all the root gall samples, okra root galls recorded maximum colonization by predacious fungi. Maximum percentage of root gall colonization was recorded for M. eudermatum followed by A. oligospora and M. ellipsosporum. M. eudermatum was also most predominant colonizer of balsam, brinjal and rice root galls.     

Quantitative distribution of meiobenthos and the structure of the free-living nematode community of the mangrove intertidal zone in Nha Trang bay (Vietnam) in the South China Sea

Meiobenthic studies were performed in an intertidal area in the Be River estuary (Nha Trang Bay, Vietnam). The study area is an area of riverine-type mangroves that have been heavily damaged by human impacts, including timber cutting and waste. Three biotopes are situated in the middle intertidal zone: a fringe of Rhizophora stylosa, a bush area composed of Avicennia aff. alba behind it, and muddy sand with fiddler crabs (Uca spp.), which is free of mangrove plants. Three replicate samples of meiobenthos were collected in each biotope and each sample was subdivided into two layers: 0–1 and 1–4 cm. The abundance of metazoan meiobenthos varied from 735 specimens/10 cm² in the Uca spp. biotope to 244 specimens/10 cm² beneath the Rhizophora trees. Six taxonomic groups of high rank were found among the meiofauna: Nematoda, Copepoda (Harpacticoida), Oligochaeta, Turbellaria, Kinorhyncha, and Foraminifera (Allogromiida). The spatial variability of meiobenthos and its key taxa was estimated and the spatial distribution patterns of free-living nematode species were described. About 90% of the total meiobenthos inhabited the upper 0–1 cm of the sediments. Nematodes constituted 90–95% of all meiobenthic organisms in the samples. A total of 48 species of free-living nematodes were found in the investigated mangrove intertidal area. In terms of species composition and set of dominants, the nematode community is comprised of three local assemblages: one of them inhabits the uppermost centimeter in the Uca and Avicennia biocenoses; the second assemblage occupies the upper sediment layer in the Rhizophora stand; a less abundant but specific assemblage of several nematode species occurs in the subsurface sediments at all three sites.     

Effects of waterlogging and salinity on plant-water relations and on the accumulation of solutes in three mangrove species

Dispersal units of Avicennia marina (Forsk.) Vierh., Rhizophora mucronata Lam. and Bruguiera gymnorrhiza (L.) Lam. were cultivated in mangrove sediment under greenhouse conditions. After 7 months plants were subjected to the following waterlogging and salinity treatments for 60 days: drained non-saline, drained saline, waterlogged non-saline and waterlogged saline. Measurements were made of stomatal resistance (r_s), tissue water potentials, relative water content, and the concentration of Na, K, Ca and Mg in plant organs. Measurements were made 4 days before the termination of waterlogging and continued for 12 days thereafter. Generally, the highest stomatal resistance occurred in the waterlogged saline treatments and the least stomatal resistance occurred in the drained non-saline treatments. Water potentials were usually lower in the saline treatments than in the non-saline treatments. Depression in water potential was greatest in Avicennia and least in Bruguiera. In all 3 species, the concentration of cations was high in the roots. Salinity had greater effects on the concentration of ions in Avicennia than in Rhizophora or Bruguiera. The low stomatal resistance, low tissue water potentials, high relative water content and high tissue cation concentration in Avicennia suggest that it is ideally suited as the pioneer in the mangrove association. Generally, Rhizophora was more tolerant of salinity than Bruguiera. The responses of the plants reveal the remarkable adaptability of mangroves to the saline environment. The adaptive features of each species determine its characteristic habitat in intertidal areas.     

Isolation of Eutypa lata from Juglans regia, and Pathogenicity Studies on Different Wood Plants

The fungus Eutypa lata was isolated from diseased walnut trees (Juglans regia) exhibiting small cankers. The morphological characteristics of the culture and the pathogenicity were compared with those of known isolates of the fungus from other hosts. Inoculation tests with walnut isolates on grape, walnut, almond and apricot yielded characteristic cankers. Furthermore, pathogenicity tests on walnut with isolates from other different hosts resulted in differences in virulence. Similar differences in virulence were observed between 13 single ascospore isolates of the fungus ex apricot inoculated on walnut.     

Fungal diversity and plant disease in mangrove forests: salt excretion as a possible defense mechanism

Keywords. Salt excretion in leaves of some mangrove species may serve as an important defense against fungal attack, reducing the vulnerability of typically high-density, monospecific forest stands to severe disease pressure. In field surveys of a Caribbean mangrove forest in Panama, Avicennia germinans suffered much less damage from foliar diseases than did Laguncularia racemosa or Rhizophora mangle. Similarly, Avicennia leaves supported the least superficial fungal growth, endophytic colonization, and diversity, followed by Laguncularia and Rhizophora. Host specificity of leaf-colonizing fungi was greater than expected at random. We hypothesize that the different salt tolerance mechanisms in the three mangrove species may differentially regulate fungal colonization. The mangroves differ in their salt tolerance mechanisms such that Avicennia (which excretes salt through leaf glands) has the highest salinity of residual rain water on leaves, Laguncularia (which accumulates salt in the leaves) has the greatest bulk salt concentration, and Rhizophora (which excludes salt at the roots) has little salt associated with leaves. The high salt concentrations associated with leaves of Avicennia and Laguncularia, but not the low salinity of Rhizophora, were sufficient to inhibit the germination of many fungi associated with mangrove forests.     

Pollen fertility and intraspecific and interspecific compatibility in mangroves of Fiji

 Pollen fertility and compatibility status were investigated in three species of mangroves: Bruguiera gymnorhiza, Rhizophora samoensis, R. stylosa and a hybrid between the two Rhizophora species. Pollen fertility was greater than 80% in the three species but less than 10% in the hybrid. Also, all three species were intraspecifically compatible, while the hybrid showed very low compatibility which may be due to its low pollen fertility. The genera Bruguiera and Rhizophora were found to be completely cross incompatible, while a low reciprocal cross compatibility was observed in interspecific crosses between Rhizophora stylosa and R. samoensis. Received: 5 June 1997 / Revision accepted: 10 October 1997     

Observations on the Occurrence of Entomophthorales Infecting Aphids (Aphidoidea) in Slovakia

The species spectrum of entomophthoralean fungi parasiting aphids was investigated in Slovakia. The surveys focused on aphid fauna occupying both agricultural crops and vegetation at non-crop sites. During the surveys, 15 different entomophthoralean species were identified from 66 aphid species. Of these 15 fungal species, eight had not previously been recorded in Slovakia and one species, Erynia erinacea (Ben-Ze’ev et Kenneth) Remaudière et Hennebert, had not been recorded previously in Central Europe. New hosts for some parasitic fungi were also recorded. The occurrence of fungal infection and the fungal species spectrum varied with sampling period and sampling area. In general, the fungi were observed parasiting aphid populations from April until November. Pandora neoaphidis (Remaudière et Hennebert) Humber was the predominant fungal pathogen and could effectively reduce aphid populations. Entomophthora planchoniana Cornu and Conidiobolus obscurus (Hall et Dunn) Remaudière et Keller were also common pathogens of aphids, but without an epizootic potential. On the other hand, Neozygites fresenii (Nowakowski) Remaudière et Keller had a strong tendency to establish epizootics in dense aphid colonies, especially in those of the black bean aphid. Other entomophthoralean species observed in the country were considered to be minor aphid pathogens on account of their low occurrence, lower specificity to aphids, or high specificity to a single aphid species. This is the first detailed report to date on the occurrence of Entomophthorales in Slovakia.     

Molecular ecology and biogeography of mangrove trees towards conceptual insights on gene flow and barriers: A review

In this review the most recent contributions to the field of molecular ecology and biogeography of mangrove trees are considered. Emphasis is on the obtained information of the different molecular marker methods used in mangrove genetics and on the potential to infer biogeographical patterns. Isozymes on average showed low or even no polymorphism in mangrove trees similar as known in seagrasses. The outcrossing Avicennia seems to be the most variable mangrove tree for isozymes. Both low amounts of interpretable allozymes and difficulties in maintaining the enzyme activity have reduced the number of successful studies during the isozyme era. Dominant marker methods (RAPD, AFLP and ISSR) were successful to demonstrate differences in amplified DNA products at large-scale geographical distances within Avicennia species and to estimate species relationships. Hybrid testing seldom revealed hybridization among tree species. The most promising markers (microsatellites or SSR) were only recently developed and will continue to provide evidence in future studies. SSR loci in Avicennia seem to show relatively low levels of polymorphism, though clearly demonstrating that populations located at the edge of the species range can be even more depauperated. Populations located more central in their native range and situated along the same coastline such as reported in Rhizophora, are expected to be only weakly differentiated due to increased levels of gene flow. Haplotypic chloroplast variants (PCR-RFLP) or sequences revealed strong genetic structuring between populations of Avicennia, Kandelia and Ceriops from different biogeographical oceanic regions. Recent views on long-distance dispersal and on gene flow across oceans as well as along the same coastline are discussed. A comparative analysis on genetic variables across species and regions indicated general trends in the partitioning of genetic variation. A conceptual map with a worldwide overview of those regions where high levels of gene flow were reported and of other regions that were considered as effective barriers, is presented. As an aim to increase the number of reliable comparisons of genetic variables across species or regions and to increase the relevance of mangrove genetics for local conservation issues, recommendations on the molecular markers and on the sampling design of individuals and populations are given within a conceptual context of evolutionary significant units.     

A review of mangrove rehabilitation in the Philippines: successes,failures and future prospects

From half a million hectares at the turn of the century, Philippine mangroves have declined to only 120,000 ha while fish/shrimp culture ponds have increased to 232,000 ha. Mangrove replanting programs have thus been popular, from community initiatives (1930s–1950s) to government-sponsored projects (1970s) to large-scale international development assistance programs (1980s to present). Planting costs escalated from less than US$100 to over $500/ha, with half of the latter amount allocated to administration, supervision and project management. Despite heavy funds for massive rehabilitation of mangrove forests over the last two decades, the long-term survival rates of mangroves are generally low at 10–20%. Poor survival can be mainly traced to two factors: inappropriate species and site selection. The favored but unsuitable Rhizophora are planted in sandy substrates of exposed coastlines instead of the natural colonizers Avicennia and Sonneratia. More significantly, planting sites are generally in the lower intertidal to subtidal zones where mangroves do not thrive rather than the optimal middle to upper intertidal levels, for a simple reason. Such ideal sites have long been converted to brackishwater fishponds whereas the former are open access areas with no ownership problems. The issue of pond ownership may be complex and difficult, but such should not outweigh ecological requirements: mangroves should be planted where fishponds are, not on seagrass beds and tidal flats where they never existed. This paper reviews eight mangrove initiatives in the Philippines and evaluates the biophysical and institutional factors behind success or failure. The authors recommend specific protocols (among them pushing for a 4:1 mangrove to pond ratio recommended for a healthy ecosystem) and wider policy directions to make mangrove rehabilitation in the country more effective.     

Analysing ethnobotanical and fishery-related importance of mangroves of the East-Godavari Delta (Andhra Pradesh, India) for conservation and management purposes

Mangrove forests, though essentially common and wide-spread, are highly threatened. Local societies along with their knowledge about the mangrove also are endangered, while they are still underrepresented as scientific research topics. With the present study we document local utilization patterns, and perception of ecosystem change. We illustrate how information generated by ethnobiological research can be used to strengthen the management of the ecosystem. This study was conducted in the Godavari mangrove forest located in the East-Godavari District of the state Andhra Pradesh in India, where mangroves have been degrading due to over-exploitation, extensive development of aquaculture, and pollution from rural and urbanized areas (Kakinada). One hundred interviews were carried out among the fisherfolk population present in two mangrove zones in the study area, a wildlife sanctuary with strong conservation status and an adjacent zone. Results from the interviews indicated that Avicennia marina (Forsk.) Vierh., a dominant species in the Godavari mangroves, is used most frequently as firewood and for construction. Multiple products of the mangrove included the bark of Ceriops decandra (Griff.) Ding Hou to dye the fishing nets and improve their durability, the bark of Aegiceras corniculatum (L.) Blanco to poison and catch fish, and the leaves of Avicennia spp. and Excoecaria agallocha L. as fodder for cattle. No medicinal uses of true mangrove species were reported, but there were a few traditional uses for mangrove associates. Utilization patterns varied in the two zones that we investigated, most likely due to differences in their ecology and legal status. The findings are discussed in relation with the demographic and socio-economic traits of the fisherfolk communities of the Godavari mangroves and indicate a clear dependency of their livelihood on the mangrove forest. Reported changes in the Godavari mangrove cover also differed in the two zones, with significantly less perceptions of a decrease in the protected area, as compared to the adjacent non-protected area. A posteriori comparisons between sequential satellite imagery (retrospective till 1977) and respondents that were at least 15 years back then, revealed a mangrove decrease which was however perceived to different extents depending on the area with which the fishermen were familiar. While local needs had not been incorporated in the existing policy, we created a framework on how data on ethnobotanical traditions, fishery-related activities and local people's perceptions of change can be incorporated into management strategies.     

Molecular phylogeny of mangroves V. Analysis of genome relationships in mangrove species using RAPD and RFLP markers

 DNA from pooled leaf samples of 11 true major mangrove, three true minor mangrove, two mangrove associate, two mangrove parasite, three terrestrial and one cultivated species were isolated for the present study. In total, 198 random amplified polymorphic DNAs (RAPDs) and 180 restriction fragment length polymorphism (RFLP) loci were scored by using ten primers and 14 enzyme-probe combinations respectively. The polymorphism observed for these markers revealed a high degree of genetic diversity in mangroves at both inter-specific or inter-generic levels. A dendrogram, constructed after pooling both RAPD and RFLP data, using a similarity index was analysed for genome relationships among these species. The dendrogram showed clustering of all the major mangroves, except for Nypa fruticans (Arecaceae), into one group. All species under the tribe Rhizophorae formed a sub-cluster, to which Xylocarpus granatum was found to be the most closesly related species. The clustering pattern implied that Excoecaria agallocha and Acanthus ilicifolius should be considered as true minor mangroves. The present study also provided molecular data favouring the separation of Avicennia spp. from the Verbenaceae to create a monotypic family the Avicenniaceae. The separation of Viscum orientale into the Viscaceae was also favoured. Received: 5 March 1998 / Accepted: 1 April 1998     

Diversity and abundance of nematode-trapping fungi from decaying litter in terrestrial, freshwater and mangrove habitats

Nematode-trapping fungi are ubiquitous in terrestrial habitats in dung, soils, litter and woody debris and they also occur in freshwater, but only one species has been found in marine habitats. The purpose of this study was therefore to investigate whether nematode-trapping fungi occurred in mangrove habitats. To achieve this we assessed the diversity of nematode-trapping fungi on decaying litter from mangroves, freshwater and terrestrial habitats (22 sites) in Hong Kong. Composite samples (n = 1,320) of decaying litter (wood and leaves) were examined and a total of 31 species of nematode-trapping fungi belonging to four genera, Arthrobotrys, Monacrosporium, and Dactylella were recorded. Twenty-nine species reported in this study are new records for Hong Kong and 16 species are new records from mangrove habitats worldwide. Nematode trapping fungi are therefore present in marine environments. Commonly encountered taxa were Arthrobotrys oligospora and Monacrosporium thaumasium which are abundant in all habitats. A. oligospora, M. thaumasium and Arthrobotrys musiformis were frequent (F > 10%). Twenty-six species were rare (0.16–9.32%). Species richness and diversity was higher in terrestrial than in freshwater and mangrove habitats (ANOVA, P < 0.001). A higher mean diversity was observed on decaying leaves as compared to decaying wood in all habitats (P < 0.001). Based on Shannon diversity index, it was also observed that taxa characterized by adhesive nets were more frequent in all habitats. This can be explained by the fact that these taxa may have a better competitive saprotrophic ability which would allow them to compete favourably in nutrient limited environments. Abiotic factors that could be linked to differences in species diversity between decaying wood and leaves are also discussed.     

An 800 year record of mangrove dynamics and human activities in the upper Gulf of Thailand

A multiproxy record comprising pollen, charcoal, loss on ignition and particle size analyses from two radiocarbon dated sediment cores from Klong Kone subdistrict on the western coast of the Gulf of Thailand provides insights on mangrove dynamics, environmental changes and human activities during the last 800 years. The mangroves were dominated by Rhizophora which indicates that the area has been influenced by the sea level from at least 820 cal bp until 720 cal bp. An intertidal area may have formed that supported mangrove development as part of an old shoreline during 820–720 cal bp. After 720 cal bp, mangroves decreased and were replaced by grasses, suggesting that a lower sea level caused the mangroves to grow closer to the sea until around 140 cal bp. Cereal pollen increased from 720 cal bp suggesting probable use of the shoreline for intensive cultivation. The mangroves were characterised by Avicennia, which increased toward the top of the 2 cores, suggesting that the mangroves then grew further inland, probably due to recent sea-level rise. Intensive human activity is recorded during the 20th century, as indicated by increased particle size, charcoal and carbonate content. At present, human activity in the area includes dams and construction as well as aquaculture.     

Frequency of occurrence of fungi on wood in Malaysian mangroves

Over one hundred fungi have been reported on mangrove wood (Hyde and Jones, 1988; Jones and Kuthubutheen, 1989; Hyde and Jones, unpublished) from tropical and subtropical locations. A variety of factors affect the frequency of occurrence of these fungi, e.g . salinity, length of exposure of substrate, wood species and location within the mangrove. Two aspects are addressed in this paper: a) Comparison of the fungi present at three mangroves in Malaysia (Morib, Kuala Selangor, Port Dickson); and b) The fungi colonising specific mangrove wood, e.g. Avecennia marina, Bruguiera gymnorrhiza. Species diversity was greatest at Port Dickson with 63 fungi recorded while species composition varied from site to site. Common fungi at Morib and Kuala Selangor were Halocyphina villosa and Leptosphaeria australiensis along with Kallichroma tethys and Lulworthia grandispora at the latter site. None of these were common at Port Dickson, the dominant species at this site were Hypoxylon oceanicum and Massarina ramunculicola. A comparison of the fungi occurring on Avicennia marina and Bruguiera gymnorrhiza indicated that Halocyphina villosa was common on both timbers. Species diversity and abundance were greatest on Avicennia with the following fungi listed as common: Eutypa sp., Kallichroma tethys, Marinosphaera mangrovei, Phoma sp. and Julelia avicenniae.