Freshwater Swamp Research Articles

Intersexual mimicry and flowering phenology facilitate pollination in a dioecious habitat specialist species, Myristica fatua (Myristicaceae)

Myristica fatua is a dioecious specialist species restricted to the endangered, freshwater Myristica swamp forests in the Western Ghats, India. Earlier studies have alluded to pollination by deception in members of the Myristica genus, and thus we examined the pollination ecology comprising floral biology, flower production, flower visitors, and reproductive success in M. fatua and inferred the potential strategies that could permit such deception in this habitat specialist tree. Male flowers provide pollen rewards for an extended period of time while female flowers are rewardless and both sexes are visited by generalist insects, mainly by honeybees and stingless bees. Bee visits were significantly more frequent and longer on male than on female flowers as bees collected pollen from male flowers. We found that flower production patterns create a preponderance of males compared to females in the swamp populations. Using a model of honeybee color vision, we found the distance between the color loci of male and female flowers and based on minimum visual angle subtended by these flowers, we suggest that the two floral sexes cannot be discriminated by bees. Bees are likely deceived by the perceptual similarity of rewardless female flowers to pollen-offering male flowers and pollination is the consequence of foraging errors made by pollinators that encounter largely male–rarely female flower mosaics as they forage among clump-distributed M. fatua trees in the swamp habitat.

Population genomics of Culiseta melanura, the principal vector of Eastern equine encephalitis virus in the United States.

BackgroundEastern Equine Encephalitis (EEE) (Togaviridae, Alphavirus) is a highly pathogenic mosquito-borne arbovirus that circulates in an enzootic cycle involving Culiseta melanura mosquitoes and wild Passeriformes birds in freshwater swamp habitats. Recently, the northeastern United States has experienced an intensification of virus activity with increased human involvement and northward expansion into new regions. In addition to its principal role in enzootic transmission of EEE virus among avian hosts, recent studies on the blood-feeding behavior of Cs. melanura throughout its geographic range suggest that this mosquito may also be involved in epizootic / epidemic transmission to equines and humans in certain locales. Variations in blood feeding behavior may be a function of host availability, environmental factors, and/or underlying genetic differences among regional populations. Despite the importance of Cs. melanura in transmission and maintenance of EEE virus, the genetics of this species remains largely unexplored.Methodology and principle findingsTo investigate the occurrence of genetic variation in Cs. melanura, the genome of this mosquito vector was sequenced resulting in a draft genome assembly of 1.28 gigabases with a contig N50 of 93.36 kilobases. Populations of Cs. melanura from 10 EEE virus foci in the eastern North America were genotyped with double-digest RAD-seq. Following alignment of reads to the reference genome, variant calling, and filtering, 40,384 SNPs were retained for downstream analyses. Subsequent analyses revealed genetic differentiation between northern and southern populations of this mosquito species. Moreover, limited fine-scale population structure was detected throughout northeastern North America, suggesting local differentiation of populations but also a history of ancestral polymorphism or contemporary gene flow. Additionally, a genetically distinct cluster was identified predominantly at two northern sites.Conclusion and significanceThis study elucidates the first evidence of fine-scale population structure in Cs. melanura throughout its eastern range and detects evidence of gene flow between populations in northeastern North America. This investigation provides the groundwork for examining the consequences of genetic variations in the populations of this mosquito species that could influence vector-host interactions and the risk of human and equine infection with EEE virus.

The Impact of Anthropogenic Intervention on the Walauwewaththa Wathurana Fresh Water Swamp Forest in Sri Lanka

Swamp forests are considered as the late succession stage of a freshwater marsh ecosystem and it is the rarest wetland type in Sri Lanka, rich in biodiversity thus providing a number of ecosystem services. The Walauwewatta Wathurana has been identified as the most dynamic fresh water ecosystem in Sri Lanka. These rare forest ecosystems have been subjected to degradation over the past decades due to various reasons especially anthropogenic activities. A study was conducted to explore the magnitude of these impacts caused by anthropogenic activities. A household survey was conducted using a structured questioner and Participatory Rural Appraisals (PRA) and discussions were made to gather information from the people living close by the swamp. Data analysis based on both quantitative and qualitative techniques. It was revealed that, a large number of activities carried out in the surrounding area of the forest by the neighboring communities directly or indirectly were related to their livelihoods as well as for their daily household needs. The richness of the species and the abundance have decreased over the past two decades due to the unsustainable fishing activities, contamination of agro-chemicals as well as chemical effluents of rubber based industries, sand mining, bamboo and rattan industries located around the forest area. Therefore the Wathurana fresh water swamp forest has been subjected to degradation due to anthropogenic activities. Conservation strategies should be implemented to strengthen the sustainability of the ecosystem services provided by this freshwater swamp forest.

Middle and late Badenian palaeoenvironments in the northern Vienna Basin and their potential link to the Badenian Salinity Crisis

AbstractHydrocarbon exploration in the Bernhardsthal and Bernhardsthal-Sued oil fields documents an up to 2000 m thick succession of middle and upper Badenian deposits in this part of the northern Vienna Basin (Austria). Based on palaeontological analyses of core-samples, well-log data and seismic surveys we propose an integrated stratigraphy and describe the depositional environments. As the middle/late Badenian boundary is correlated with the Langhian/Serravallian boundary, the cores capture the crucial phase of the Middle Miocene Climate Transition. The middle Badenian starts with a major transgression leading to outer neritic to upper bathyal conditions in the northern Vienna Basin, indicated byBathysiphon-assemblages and glass-sponges. A strong palaeo-relief and rapid synsedimentary subsidence accentuated sedimentation during this phase. The middle/late Badenian boundary coincides with a major drop of relative sea level by about 200 m, resulting in a rapid shift from deeper marine depositional environments to coastal and freshwater swamps. In coeval marine settings, a more than 100 m thick unit of anhydrite-bearing clay formed. This is the first evidence of evaporite precipitation during the Badenian Salinity Crisis in the Vienna Basin. Shallow lagoonal environments with diverse and fully marine mollusc and fish assemblages were established during the subsequent late Badenian re-flooding. In composition, the mollusc fauna differs considerably from older ones and is characterized by the sudden appearance of species with eastern Paratethyan affinities.

Acoustic monitoring reveals diversity and surprising dynamics in tropical freshwater soundscapes

Abstract Freshwater systems are globally threatened and in need of enhanced monitoring and assessment. We applied soundscape recording and analysis—which presents an opportunity for long‐term, high‐resolution animal community monitoring and assessment—to a freshwater context to better understand the acoustic diversity and dynamics of these systems. We recorded the aquatic soundscape of a Neotropical freshwater swamp in Costa Rica for 23 days in January and February 2015 during the dry season. We classified biological sound types in these recordings and developed measurements of richness and occupancy based on this classification. We also calculated six complementary acoustic indices to assess soundscape diversity and daily and longer‐term soundscape dynamics, and we examined correlations between these acoustic indices and sound type metrics. We found rich soundscapes in which biological sounds were almost always present, and we classified 18 sound types that we attribute to aquatic insects. These sound types showed distinct daily patterns and exhibited temporal and spectral acoustic niche partitioning. Sound type richness was most correlated with the number of peaks index (correlation = .36; p < .001), while sound type occupancy was most correlated with the Bioacoustic Index (correlation = .92; p < .001). In contrast to generally high levels of acoustic activity, there were brief (approximately 1 hr), unexpected quiet periods around dawn and dusk. This study represents an early attempt to comprehensively describe tropical freshwater soundscapes in a systematic and quantitative manner. We demonstrate that sound type classification and the quantification of acoustic occupancy capture aspects of soundscape diversity and dynamics that are complementary to those assessed by acoustic indices. Our analyses reveal that the soundscapes of this tropical wetland were diverse and exhibited daily dynamics that differed from those found in other ecosystems.

Integrated research, conservation and management of Nee Soon freshwater swamp forest, Singapore: hydrology and biodiversity

The current paper acts as an introduction to nine following papers concerning the hydrology and biodiversity of Nee Soon freshwater swamp forest. Freshwater swamp forest is a threatened and overlooked

Diversity of terrestrial snails and slugs in Nee Soon freshwater swamp forest, Singapore

Diversity of terrestrial snails and slugs in Nee Soon freshwater swamp forest, Singapore

The hydro-geomorphic status of Nee Soon freshwater swamp forest catchment of Singapore

The hydro-geomorphic status of Nee Soon freshwater swamp forest catchment of Singapore

The biological, ecological and conservation significance of freshwater swamp forest in Singapore

The Nee Soon stream drainage in the Central Catchment Nature Reserve is virtually the last remaining fragment of primary freshwater swamp forest in Singapore. The forest type has been poorly studied i

Next-Generation identification tools for Nee Soon freshwater swamp forest, Singapore

Next-Generation identification tools for Nee Soon freshwater swamp forest, Singapore

Diversity, distribution and habitat characteristics of dragonflies in Nee Soon freshwater swamp forest, Singapore

Biodiversity baselines were established for dragonflies of Nee Soon freshwater swamp forest based on quantitative sampling across the eight sub-ctachments. Surveys were conducted from december 2014 to

Projected impacts of climate change on stream flow and groundwater of Nee Soon freshwater swamp forest, Singapore

As Singapores only remaining patch of primary freshwater swamp forest, the good management of the Nee Soon catchment is of utmost importance if a large proportion of the flora and fauna in Singapore i

Conservation outputs and recommendations for Nee Soon freshwater swamp forest, Singapore

The current paper acts as a summary to the Nee Soon Swamp Forest biodiversity and hydrology baseline studies project, including results published previously and the results from papers of the current

Aquatic macroinvertebrate richness, abundance and distribution in the Nee Soon freshwater swamp forest, Singapore

The Nee Soon freshwater swamp forest is a vital area for biodiversity conservation in Singapore. A survey of the aquatic macroinvertebrates in the streams of the Nee Soon drainage was carried out to c

Recycling of phenolic compounds in Borneo\u2019s tropical peat swamp forests

BackgroundTropical peat swamp forests (TPSF) are globally significant carbon stores, sequestering carbon mainly as phenolic polymers and phenolic compounds (particularly as lignin and its derivatives) in peat layers, in plants, and in the acidic blackwaters. Previous studies show that TPSF plants have particularly high levels of phenolic compounds which inhibit the decomposition of organic matter and thus promote peat accumulation. The studies of phenolic compounds are thus crucial to further understand how TPSF function with respect to carbon sequestration. Here we present a study of cycling of phenolic compounds in five forests in Borneo differing in flooding and acidity, leaching of phenolic compounds from senescent Macaranga pruinosa leaves, and absorption of phenolics by M. pruinosa seedlings.ResultsThe results of the study show that total phenolic content (TPC) in soil and leaves of three species of Macaranga were highest in TPSF followed by freshwater swamp forest and flooded limestone forest, then dry land sites. Highest TPC values were associated with acidity (in TPSF) and waterlogging (in flooded forests). Moreover, phenolic compounds are rapidly leached from fallen senescent leaves, and could be reabsorbed by tree roots and converted into more complex phenolics within the leaves.ConclusionsExtreme conditions—waterlogging and acidity—may facilitate uptake and synthesis of protective phenolic compounds which are essential for impeded decomposition of organic matter in TPSF. Conversely, the ongoing drainage and degradation of TPSF, particularly for conversion to oil palm plantations, reverses the conditions necessary for peat accretion and carbon sequestration.

Floristic Composition and Diversity of Freshwater Swamp Forests in the Niger Basin of Nigeria

Freshwater swamp forests are wetland ecosystems with poorly understood ecology. With increasing degradation across the Niger basin (where it is the most extensive across West Africa), it is deemed important to understand its distribution, patterns and composition. This is aimed at both increasing botanical inventories in the ecosystem and also elucidate vital steps that could guide its effective conservation. This study assessed the floristic composition and diversity across 16 one hectare forest plots and sought to show how varied the sites were in terms of diversity, stem density and basal area. The survey showed that the area had 116 species within 82 genera and 36 families. The number of species found in each of the disturbed sites was generally higher than the intact forest sites, which was not diverse but comprised many trees with higher basal area. While the stem density which ranged from 94 - 409 stems·ha-1 is comparable with that of other tropical forests, species richness was low (ranging from 8.65 - 0.52). Diversity ranged from 3.38 - 0.98 and was higher in disturbed sites than in intact locations. Species richness was generally low and implies that loss of species in the ecosystem could threaten species’ existence and conservation in the ecosystem. Disturbed locations had more species than the intact zones and as such show the importance of targeted conservation not only in the undisturbed locations but also in the disturbed locations with a higher species value and potential for species stability of the ecosystem.

Ecological patterns and sustainability of freshwater swamp forest ecosystems: assessing climate and disturbance interactions

Species composition and factors that control the distribution of freshwater swamp forests in West Africa are largely unknown. To achieve this, 24, one‐hectare forest plots were established to assess the tree species (DBH ≥ 10 cm) distribution across the ecosystem. A total of 138 species within 100 genera and 41 families were distributed across the forest plots and 47 species were identified as indicator species. These indicator species were used to constrain the species‐environmental categories across three broad habitat types: the disturbed freshwater zone, the mangrove‐freshwater transition zone and the intact freshwater zone. While 40 species are associated with one of the three forest categories, seven of them coexisted in disturbed and mangrove‐freshwater zones. Disturbance (local factors) was identified as the most important determinant of the species distribution followed by the climatic factors. Future climate predictions for the locations are quite variable and suggest that some species may be non‐viable as the ecosystem's composition may alter. While the indicator species provides insights on the species‐environment relationships, and is useful for informing forest conservation and planning, their tendency to continually co‐exist with others and provide vital functions is dependent on how sustainably the people use them.

Small-scale variability in a mosaic tropical rainforest influences habitat use of long-tailed macaques.

Pristine habitats have generally been considered to be the most important ecological resource for wildlife conservation, but due to forest degradation caused by human activities, mosaics of secondary forests have become increasingly prominent. We studied three forest types in a mosaic tropical forest consisting of short secondary forest (SS), tall secondary forest (TS) and freshwater swamp forest (SF). These forests differed in stand structure and floristic composition, as well as phenological productivity of fruits, flowers and young leaves. We examined habitat use of long-tailed macaques (Macaca fascicularis) in relation to indices of phenological activity. The macaques used the SS for feeding/foraging more than the TS and the SF. This was because the SS had higher productivity of fruit, which is a preferred food resource for macaques. Stem densities of young leaves in the SS and the TS also influenced habitat use, as they provided more clumped resources. Use of SF was limited, but these forests provided more species-rich resources. Our results showed that M. fascicularis responded to small-scale variability in phenological activity between forest types found in a heterogeneous mosaic forest, with young secondary regrowth forests likely providing the most important food resources. Mosaic landscapes may be important as they can buffer the effects of temporal food resource variability in any given forest type. In our increasingly human-altered landscapes, a better understanding of the role of secondary forest mosaics is crucial to the conservation and management of wildlife habitats and the animals they support.

Conservation of Freshwater Fishes

The global diversity of freshwater fishes, estimated in 2013 as 15,750, is nearly half of the global diversity of all fishes (currently estimated at 33,984), yet freshwater lakes, swamps, and strea...

Ground dwelling pygmy grasshoppers (Orthoptera: Tetrigidae) in Southeast Asian tropical freshwater swamp forest prefer wet microhabitats

Ground dwelling pygmy grasshoppers (Orthoptera: Tetrigidae) in Southeast Asian tropical freshwater swamp forest prefer wet microhabitats