Culex pipiens and Culex restuans larval interactions shape the bacterial communities in container aquatic habitats.

Container aquatic habitats host a community of aquatic insects, primarily mosquito larvae that browse on container surface microbial biofilm and filter-feed on microorganisms in the water column. We examined how the bacterial communities in these habitats respond to feeding by larvae of two container-dwelling mosquito species, Culex pipiens and Cx. restuans. We also investigated how the microbiota of these larvae is impacted by intra- and interspecific interactions. Microbial diversity and richness were significantly higher in water samples when mosquito larvae were present, and in Cx. restuans compared to Cx. pipiens larvae. Microbial communities of water samples clustered based on the presence or absence of mosquito larvae and were distinct from those of mosquito larvae. Culex pipiens and Cx. restuans larvae harbored distinct microbial communities when reared under intraspecific conditions and similar microbial communities when reared under interspecific conditions. These findings demonstrate that mosquito larvae play a major role in structuring the microbial communities in container habitats and that intra- and interspecific interactions in mosquito larvae may shape their microbiota. This has important ecological and public health implications since larvae of the two mosquito species are major occupants of container habitats while the adults are vectors of West Nile virus.

Relationships between biological age, distance from aquatic habitats and pyrethroid resistance status of Anopheles funestus mosquitoes in south-eastern Tanzania.

BACKGROUND: Malaria transmission can be highly heterogeneous between and within localities, and is influenced by factors such as survival and biting frequencies of Anopheles mosquitoes. This study investigated the relationships between the biological age, distance from aquatic habitats and pyrethroid resistance status of Anopheles funestus mosquitoes, which currently dominate malaria transmission in south-east Tanzania. The study also examined how such relationships may influence malaria transmission and control. METHODS: Female An. funestus were collected in houses located 50-100 m, 150-200 m or over 200 m from the nearest known aquatic habitats. The mosquitoes were exposed to 1×, 5× and 10× the diagnostic doses of deltamethrin or permethrin, or to the synergist, piperonyl butoxide (PBO) followed by the pyrethroids, then monitored for 24 h-mortality. Ovaries of exposed and non-exposed mosquitoes were dissected to assess parity as a proxy for biological age. Adults emerging from larval collections in the same villages were tested against the same insecticides at 3-5, 8-11 or 17-20 days old. FINDINGS: Mosquitoes collected nearest to the aquatic habitats (50-100 m) had the lowest mortalities compared to other distances, with a maximum of 51% mortality at 10× permethrin. For the age-synchronized mosquitoes collected as larvae, the insecticide-induced mortality assessed at both the diagnostic and multiplicative doses (1×, 5× and 10×) increased with mosquito age. The highest mortalities at 1× doses were observed among the oldest mosquitoes (17-20 days). At 10× doses, mortalities were 99% (permethrin) and 76% (deltamethrin) among 8-11 day-olds compared to 80% (permethrin) and 58% (deltamethrin) among 3-5 day-olds. Pre-exposure to PBO increased the potency of both pyrethroids. The proportion of parous females was highest among mosquitoes collected farthest from the habitats. CONCLUSION: In this specific setting, older An. funestus and those collected farthest from the aquatic habitats (near the centre of the village) were more susceptible to pyrethroids than the younger ones and those caught nearest to the habitats. These findings suggest that pyrethroid-based interventions may remain at least moderately effective despite widespread pyrethroid-resistance, by killing the older, less-resistant and potentially-infective mosquitoes. Further studies should investigate how and whether these observations could be exploited to optimize malaria control in different settings.

Postmortem submersion interval estimation of cadavers recovered from freshwater based on gut microbial community succession.

Microbial community succession during decomposition has been proven to be a useful tool for postmortem interval (PMI) estimation. Numerous studies have shown that the intestinal microbial community presented chronological changes after death and was stable in terrestrial corpses with different causes of death. However, the postmortem pattern of intestinal microbial community succession in cadavers retrieved from water remains unclear. For immersed corpses, the postmortem submersion interval (PMSI) is a useful indicator of PMI. To provide reliable estimates of PMSI in forensic investigations, we investigated the gut microbial community succession of corpses submersed in freshwater and explored its potential application in forensic investigation. In this study, the intestinal microbial community of mouse submersed in freshwater that died of drowning or CO2 asphyxia (i.e., postmortem submersion) were characterized by 16S rDNA amplification and high-throughput sequencing, followed by bioinformatic analyses. The results demonstrated that the chronological changes in intestinal bacterial communities were not different between the drowning and postmortem submersion groups. α-diversity decreased significantly within 14 days of decomposition in both groups, and the ß-diversity bacterial community structure ordinated chronologically, inferring the functional pathway and phenotype. To estimate PMSI, a regression model was established by random forest (RF) algorithm based on the succession of postmortem microbiota. Furthermore, 15 genera, including Proteus, Enterococcus, and others, were selected as candidate biomarkers to set up a concise predicted model, which provided a prediction of PMSI [MAE (± SE) = 0.818 (± 0.165) d]. Overall, our present study provides evidence that intestinal microbial community succession would be a valuable marker to estimate the PMSI of corpses submerged in an aquatic habitat.

Assessment of the Toxic Effects of Heavy Metals on Waterbirds and Their Prey Species in Freshwater Habitats.

Waterbirds may be a good indicator of harmful metal levels in aquatic environments. Waterbirds' organs and tissues were tested for the presence of pollutants, such as metals. However, very few reports describe the use of bird feathers and their prey in metal analysis. In the present research, seven metals were measured in the tissue, kidney, liver, and feathers of the Indian pond heron, the black-crowned night heron, and their prey species, including crabs, prawns, molluscs, and fishes from a freshwater lake. Metals were examined using an ECIL-4141-double beam atomic absorption spectrophotometer (DB-AAS). Metal concentrations differed considerably in the tissue, kidney, liver, and feathers of the Indian pond heron and black-crowned night heron (p < 0.001). Indeed, this research discovered a good correlation between the metals of prey species and the tissues, kidneys, liver, and feathers of waterbirds that were tested. The regression model explained that the Cyprinus carpio influence the accumulation of metals about 98.2% in tissues, Macrobrachium rosenbergii and Cyprinus carpio around 86.3% in the kidney, the Labeo rohita almost 47.2% in the liver and Labeo rohita nearly 93.2% on the feathers of the Indian pond heron. On the other hand, the Mystus vittatus, Cyprinus carpio, Labeo rohita influence about 98.8% in tissue, the Claris batrachus and Tilapia mossambica around 93.3% in kidney, the Mystus vittatus, Cyprinus carpio, about 93.2% in liver and the freshwater crab (Travancoriana schirnerae), freshwater prawn (Macrobrachium rosenbergii) and a fish (Cyprinus carpio) nearly 93.2% in feathers in the black-crowned night heron. This research evaluated metals in the dead carcasses of waterbirds, a non-invasive biomonitoring technique for pollution. Overall, the investigation revealed that the lake is severely contaminated with metals. Therefore, the management and protection of aquatic habitats, particularly freshwater lakes, should be enhanced to rescue wild species that rely on aquatic ecosystems and to ensure that people have access to clean drinking water.

Searching Metagenomes for New Rhodopsins.

Most microbial groups have not been cultivated yet, and the only way to approach the enormous diversity of rhodopsins that they contain in a sensible timeframe is through the analysis of their genomes. High-throughput sequencing technologies have allowed the release of community genomics (metagenomics) of many habitats in the photic zones of the ocean and lakes. Already the harvest is impressive and included from the first bacterial rhodopsin (proteorhodopsin) to the recent discovery of heliorhodopsin by functional metagenomics. However, the search continues using bioinformatic or biochemical routes.

Evolution and Physiology of Amphibious Yeasts.

Since the emergence of the first fungi some 700 million years ago, unicellular yeast-like forms have emerged multiple times in independent lineages via convergent evolution. While tens to hundreds of millions of years separate the independent evolution of these unicellular organisms, they share remarkable phenotypic and metabolic similarities, and all have streamlined genomes. Yeasts occur in every aquatic environment yet examined. Many species are aquatic; perhaps most are amphibious. How these species have evolved to thrive in aquatic habitats is fundamental to understanding functions and evolutionary mechanisms in this unique group of fungi. Here we review the state of knowledge of the physiological and ecological diversity of amphibious yeasts and their key evolutionary adaptations enabling survival in aquatic habitats. We emphasize some genera previously thought to be exclusively terrestrial. Finally, we discuss the ability of many yeasts to survive in extreme habitats and how this might lend insight into ecological plasticity, including amphibious lifestyles.

Establishing the relationship between benthic macroinvertebrates and water level fluctuation in subtropical shallow wetlands.

Wetland water level fluctuations often influence benthic macroinvertebrate communities through changes in water quality, substrate, and macrophytes and, hence, affect the structure and function of aquatic ecosystems. However, there is lack of understanding on how water level fluctuations affect the structure and composition of benthic macroinvertebrates in subtropical shallow wetlands in Nepal. Here, we assessed the changes in benthic macroinvertebrate community composition in response to water level fluctuations and identified indicator taxa sensitive to such fluctuations. A study was conducted over 4 seasons covering one annual cycle of water level fluctuation in 4 wetlands of Koshi Tappu Wildlife Reserve, Nepal. The study revealed that benthic macroinvertebrate composition significantly differed across water levels. Dissimilarities in macroinvertebrate community composition were mainly attributed by families Atyidae, Dytiscidae, Baetidae, Planorbidae, Chironomidae, Bithyniidae, Sphaeriidae, and Thiaridae. Taxon specific richness, densities, and biomass varied across the water levels while no difference was documented for overall family richness, density, and biomass. Ephemeroptera and Trichoptera richness decreased when water levels were low while Coleoptera and Diptera richness increased. Medium water level supported high benthic macroinvertebrate diversity. Indicator taxa analysis identified Coleoptera: Hydrophilidae and Dytiscidae, Hemiptera: Pleidae, Diptera: Muscidae and Mollusca: Sphaeriidae, Viviparidae, and Thiaridae, as indicators of low water level. Similarly, Coleoptera: Scirtidae, Hemiptera: Micronectidae and Oligochaeta: Tubificidae as indicators of medium water level, and Trichoptera: Polycentropodidae and Ephemeroptera: Caenidae as indicators of high water level. Redundancy analysis identified water level as one of the most influencing factors in benthic macroinvertebrate community variation. Considering the significant response of benthic macroinvertebrates to water level fluctuations, they are important as ecological indicators in research aimed at developing environmental flow frameworks. Indicator species are likely to be a vital tool in environmental impact assessment and monitoring in relation to hydrological development. The outcomes of this research have important implications to conservation and management of wetlands to preserve the valuable ecosystem functions provided by wetlands.

Integrative Taxonomic, Ecological and Genotyping Study of Charophyte Populations from the Egyptian Western-Desert Oases and Sinai Peninsula.

Present-day information available on the charophyte macroalgae in Egypt, including their phylogenetic affinities, remains largely incomplete. In this study, nine charophyte populations were collected from different aquatic biotopes across the Egyptian Western-Desert Oases and Sinai Peninsula. All populations were investigated using an integrative polyphasic approach including phylogenetic analyses inferred from the chloroplast-encoded gene (rbcL) and the internal transcribed spacer (ITS1) regions, in parallel with morphotaxonomic assignment, ultrastructure of the oospore walls, and autecology. The specimens identified belonged to the genera Chara, Nitella, and Tolypella, with predominance of the first genus to which five species were assigned though they presented some interesting aberrant taxonomic features: C. aspera, C. contraria, C. globata, C. tomentosa, and C. vulgaris. Based on our integrative study, the globally rare species C. globata was reported for the second time for the whole African continent. The genus Nitella was only represented by N. flagellifera, and based on the available literature, it is a new record for North Africa. Noteworthy, an interesting Tolypella sp., morphologically very similar to T. glomerata, was collected and characterized and finally designated with the working name 'Tolypella sp. PBA-1704 from a desert, freshwater wetland', mainly based on its concatenated rbcL+ITS1 phylogenetic position. This study not only improved our understanding on the diversity, biogeography and autecological preferences of charophytes in Egypt, but it also broadened our knowledge on this vulnerable algal group in North Africa, emphasizing the need of more in-depth research work in the future, particularly in the less-impacted desert habitats.

Identification and characterization of immature Anopheles and culicines (Diptera: Culicidae) at three sites of varying malaria transmission intensities in Uganda.

BACKGROUND: Over the last two decades, there has been remarkable progress in malaria control in sub-Saharan Africa, due mainly to the massive deployment of long-lasting insecticidal nets and indoor residual spraying. Despite these gains, it is clear that in many situations, additional interventions are needed to further reduce malaria transmission. The World Health Organization (WHO) has promoted the Integrated Vector Management (IVM) approach through its Global Vector Control Response 2017-2030. However, prior roll-out of larval source management (LSM) as part of IVM, knowledge on ecology of larval aquatic habitats is required. METHODS: Aquatic habitats colonized by immature Anopheles and culicines vectors were characterized at three sites of low, medium and high malaria transmission in Uganda from October 2011 to June 2015. Larval surveys were conducted along transects in each site and aquatic habitats described according to type and size. Immature Anopheles, culicines and pupae from the described habitats were sampled using standard dipping methods to determine larval and pupae densities. Larvae were identified as anopheline or culicine, and counted. Pupae were not identified further. Binary logistic regression analysis was used to identify factors associated with the presence of immature Anopheles and culicines in each site. RESULTS: A total of 1205 larval aquatic habitats were surveyed and yielded a total of 17,028 anopheline larvae, 26,958 culicine larvae and 1189 pupae. Peaks in larval abundance occurred in all sites in March-May and August-October coinciding with the rainy seasons. Anopheles larvae were found in 52.4% (n = 251) of aquatic habitats in Tororo, a site of high transmission, 41.9% (n = 536) of habitats in Kanungu, a site with moderate malaria transmission, and 15.8% (n = 418) in Jinja, a site with low malaria transmission. The odds of finding larvae was highest in rice fields compared to pools in both Tororo (odds ratio, OR = 4.21, 95% CI 1.22-14.56, p = 0.02) and Kanungu (OR = 2.14, 95% CI 1.12-4.07, p = 0.02), while in Jinja the odd were highest in containers (OR = 4.55, 95% CI = 1.09-19.14, p = 0.03). In Kanungu, larvae were less likely to be found in containers compared to pools (OR = 0.26, 95% CI 0.09-0.66, p = 0.008) and river fringe (OR = 0.19, 95% CI 0.07-0.52, p = 0.001). Medium sized habitats were associated with high odds of finding larvae compared to small habitats (OR = 3.59, 95% CI 1.18-14.19, p = 0.039). CONCLUSIONS: These findings show that immature Anopheles and culicines were common in areas of high and moderate transmission but were rare in areas of low transmission. Although immature Anopheles and culicines were found in all types of water bodies, they were most common in rice fields and less common in open drains and in river fringes. Methods are needed to reduce the aquatic stages of anopheline mosquitoes in human-made habitats, particularly rice fields.

Microbial communities of container aquatic habitats shift in response to Culex restuans larvae.

We examined how larvae of Culex restuans mosquito influences the bacterial abundance, composition and diversity in simulated container aquatic habitats. The microbiota of Cx. restuans larvae were also characterized and compared to those of their larval habitats. The presence of Cx. restuans larvae altered the bacterial community composition and reduced the bacterial abundance, diversity and richness. Azohydromonas sp., Delftia sp., Pseudomonas sp., Zooglea sp., unclassified Enterobacteriaceae and unclassified Bacteroidales were suppressed while Prosthecobacter sp., Hydrogenaphaga sp., Clostridium sp., unclassified Clostridiaceae and Chryseobacterium sp. were enhanced in the presence of Cx. restuans larvae. Cx. restuans larvae harbored distinct and less diverse bacterial community compared to their larval habitats. These findings demonstrate that Cx. restuans larvae play a key role in structuring the microbial communities in container aquatic habitats and may lower the nutritional quality and alter the decomposition process and food web dynamics in these aquatic systems. The findings also demonstrate that mosquito larvae are highly selective of the bacterial taxa from the larval environment that colonize their bodies. These findings provide new opportunities for more focused studies to identify the specific bacterial taxa that serve as food for mosquito larvae and those that could be harnessed for disease control.

Uptake of 133Cs and 134Cs by Ceratophyllum demersum L. under field and greenhouse conditions.

The phytoremediation abilities of Hornwort (Ceratophyllum demersum L.) were tested under greenhouse and field conditions. Plants were exposed for 8, 16, and 24 days (greenhouse with stable isotope 133Cs), 8 days (field with 133Cs), and 8 days (climabox with radioactive isotope 134Cs). The plants were exposed to different concentration of stable Cs provided as CsCl (0.008, 0.033, 0.133, 0.267, 0.533, 0.800, 1.067, and 1.333 mM) and different activities of 134Cs (4.46, 4.46, 4.74, 4.64, 2.23 and 2.26 kBq). The results of the experiment revealed a significant effect (p < 0.001) of exposure time on Cs uptake. The results showed highest average 133Cs removal rates of 11%, 17% and 19% for 8, 16, and 24 days, respectively, in the greenhouse, 10% for the 134Cs experiment, and 27% for the field experiment with 133Cs. The results indicated that increasing the length of exposure lowered the uptake ability, hence indicating that the plant has limited capacity for Cs removal. The accumulated amount of Cs by plants is significantly dependent (p < 0.001) on the concentration of treatment and complies to a sigmoid curve. Comparison of experiments revealed the greenhouse experiment with 133Cs and the experiment with 134Cs did not differ significantly in their removal rate. However, the field experiment was significantly different from the previous two (p < 0.001), providing a higher removal rate. C. demersum was also able to resist phytotoxic effects of Cs in the greenhouse experiment for 16 days without significant effects (p > 0.05) on health. Even after 24 days of exposure, the plant resisted up to 0.267 mM treatment concentration with no significant tissue lesion (p > 0.05). These results indicate that C. demersum has potential for remediating aquatic habitats, especially in the case of acute events, where a short duration of phytoremediation may take place.

Detection and quantification of Anopheles gambiae sensu lato mosquito larvae in experimental aquatic habitats using environmental DNA (eDNA).

Background: Growing insecticide resistance and changes in biting and resting behavior of malaria vectors threaten efficacy of insecticide treated nets and indoor residual spraying. Larval source management (LSM) is a promising approach that can target mosquitoes irrespective of their behavior as adults. However, the use of traditional monitoring methods for immature stages of Anopheles mosquitoes is a major challenge to LSM due to the variability in their breeding habitats.  We evaluate the use of an environmental DNA (eDNA) analysis technique in monitoring Anopheles gambiae sensu lato larvae in experimental aquatic habitats. Methods: eDNA was simultaneously sampled and extracted from different volumes of water, number of larvae, and occupation time. Larval presence was detected using PCR and eDNA concentration in samples from 1 L habitats quantified using an IGS and cyt b TaqMan assays. The limit of detection of the two assays was tested and larval density correlated with eDNA positivity. Results: 74% of replicates in the 50 mL habitats were PCR positive with at least 6h required to get a signal from a single larva (0.02 larvae/mL). All 12 replicates where 1 L of water was used were positive with stronger PCR bands than replicates with the same larval density in 50 mL for 24 h. There was a correlation between larval densities and eDNA detection in both assays: IGS, r = 0.503, p = 0.047; and cyt b,r = 0.558, p = 0.025. There was stochasticity in eDNA detection rates, using both PCR and qPCR across all the dilutions. Conclusion: This study has demonstrated the potential use of eDNA analysis for detection and quantification of An. gambiae s.s. mosquito larvae in aquatic habitats. The stochasticity observed in eDNA detection suggest that this technique is best for monitoring aquatic habitats with many larvae at low densities.

Madicolous Chironomidae from the Brazilian Atlantic Forest: a checklist with notes on altitudinal distributions (Diptera, Insecta).

Thin layers of water running over rocky surfaces are characteristic of madicolous habitats, which harbor a peculiar Chironomidae community. However, information on the identity, distribution, and ecology of madicolous chironomids in the Neotropical region are still sparse. The main purpose of this research is to reveal and contribute to the ecology of madicolous Chironomidae species, especially regarding their altitudinal distribution in the Atlantic Forest. Sampling was performed using our own designed emergence traps deployed from 0 to 2700 m a.s.l. in 70 sites in three mountains in southeastern Brazil. Sixty taxa of chironomids were collected and identified, of which only 22 are known to science. Most of the species showed a wider distribution than previously known, both in terms of geographic and altitudinal ranges, while others showed significant association with particular altitudinal bands (as evidenced by the indicator species analysis). Atlantic Forest mountainous regions are known to harbor one of the richest fauna in the world and have been suffering from several types of environmental impacts, including climate change, which will especially affect taxa living in specialized habitats. The narrow range of tolerance to environmental conditions verified for mountain species, and the fact that many of them are rare and endemic, make the conservation efforts in these areas indispensable.

Distinct diversity patterns of Planctomycetes associated with the freshwater macrophyte Nuphar lutea (L.) Smith.

Members of the phylum Planctomycetes were originally described as freshwater bacteria. Most recent studies, however, address planctomycete diversity in other environments colonized by these microorganisms, including marine and terrestrial ecosystems. This study was initiated in order to revisit the specific patterns of planctomycete diversity in freshwater habitats using cultivation-independent approaches. The specific focus was made on planctomycetes associated with Nuphar lutea (L.) Smith, an emergent macrophyte with floating leaves, which is widespread in the Holarctic. As revealed by Illumina pair-end sequencing of 16S rRNA gene fragments, the bacterial assemblages colonizing floating leaf blades of waterlilies sampled from two different boreal lakes displayed similar composition but were distinct from the planktonic bacterial communities. 16S rRNA gene fragments from the Planctomycetes comprised 0.1-1 and 1-2.2% of total 16S rRNA gene reads retrieved from water samples and plant leaves, respectively. Planktonic planctomycetes were mostly affiliated with the class Planctomycetaceae (77-97%), while members of the Phycisphaerae were less abundant (3-22%). The relative proportion of the latter group, however, increased by 13-45% on leaves of N. lutea. The Phycisphaera-related group WD2101, Pirellula-like planctomycetes, as well as Gemmata, Zavarzinella and Planctopirus species were the most abundant groups of planctomycetes associated with plant leaves, which may suggest their involvement in the degradation of plant-derived organic matter.

Longitudinal assessment of hydropeaking impacts on various scales for an improved process understanding and the design of mitigation measures.

Hydropeaking is one of the main pressures on the aquatic ecology in alpine rivers. Beside studies on abiotic process and biotic response on the local scale there is a lack in process understanding on the reach scale. Especially longitudinal changes of hydropeaking impacts based on retention processes have not been studied yet. Thus, based on unsteady one-dimensional and two-dimensional depth averaged modelling it was targeted to investigate possible changes in vertical ramping velocity for the discussion of possible mitigation measures at the local scale. Here, we compared artificial and natural sheltering habitats in terms of peak flow. Additionally, the hydropeaking assessment on various river scales was supported by an evaluation of tributaries in an alpine river system. Based on the modelling results and the discussion of the impact assessment of hydropeaking in different case studies we state, that on the first 5km downstream of the turbine outlet a significant decrease in vertical ramping velocity occurs. In this reach, habitat improvements should focus on increasing retention processes considering the higher risk of stranding for juvenile fish and macroinvertebrates. For morphological mitigation measures at the local scale, it turned out that self-formed, near-natural morphology should be targeted in terms of mitigation measure design compared to artificial sheltering habitats. Abundance and biomass of macroinvertebrates are directly linked to substrate variability in self-formed sheltering habitats downstream of gravel bars. Moreover, we ascertained that tributaries are able to contribute to the 'ecological potential' in multi-stressed hydropeaking rivers by providing spawning and rearing habitats for fish. However, for a sustainable improvement of the aquatic environment on all relevant scales, both sediment and flood dynamics have to be considered as important drivers to establish self-formed sheltering habitats in terms of hydropeaking.

Molecular Characterization and Phylogenetic Analysis of Pseudomonas aeruginosa Isolates Recovered from Greek Aquatic Habitats Implementing the Double-Locus Sequence Typing Scheme.

The recently described double-locus sequence typing (DLST) scheme implemented to deeply characterize the genetic profiles of 52 resistant environmental Pseudomonas aeruginosa isolates deriving from aquatic habitats of Greece. DLST scheme was able not only to assign an already known allelic profile to the majority of the isolates but also to recognize two new ones (ms217-190, ms217-191) with high discriminatory power. A third locus (oprD) was also used for the molecular typing, which has been found to be fundamental for the phylogenetic analysis of environmental isolates given the resulted increased discrimination between the isolates. Additionally, the circulation of acquired resistant mechanisms in the aquatic habitats according to their genetic profiles was proved to be more extent. Hereby, we suggest that the combination of the DLST to oprD typing can discriminate phenotypically and genetically related environmental P. aeruginosa isolates providing reliable phylogenetic analysis at a local level.

AM fungal communities inhabiting the roots of submerged aquatic plant Lobelia dortmanna are diverse and include a high proportion of novel taxa.

While the arbuscular mycorrhizal (AM) symbiosis is known to be widespread in terrestrial ecosystems, there is growing evidence that aquatic plants also form the symbiosis. It has been suggested that symbiosis with AM fungi may represent an important adaptation for isoëtid plants growing on nutrient-poor sediments in oligotrophic lakes. In this study, we address AM fungal root colonization intensity, richness and community composition (based on small subunit (SSU) ribosomal RNA (rRNA) gene sequencing) in five populations of the isoëtid plant species Lobelia dortmanna inhabiting oligotrophic lakes in Southern Sweden. We found that the roots of L. dortmanna hosted rich AM fungal communities and about 15 % of the detected molecular taxa were previously unrecorded. AM fungal root colonization intensity and taxon richness varied along an environmental gradient, being higher in oligotrophic and lower in mesotrophic lakes. The overall phylogenetic structure of this aquatic fungal community differed from that described in terrestrial systems: The roots of L. dortmanna hosted more Archaeosporaceae and fewer Glomeraceae taxa than would be expected based on global data from terrestrial AM fungal communities.

The occurrence of bioactive micromonosporae in aquatic habitats of the Sunshine Coast in Australia.

Screening strategies based on the ecological knowledge of antibiotic producing microorganisms and their roles in the natural environment are being increasingly employed in the search for novel antibiotic agents. Micromonosporae are common inhabitants of aquatic habitats and have proved to be a continuing source of novel bioactive compounds including antibacterial and antitumor agents. The ecological distribution and frequency of bioactive micromonosporae in Sunshine Coast region aquatic habitats were studied through a range of selective isolation procedures designed to negatively select against the isolation of unwanted microbial taxa commonly associated with marine environments. It was revealed that bioactive compound producing species of micromonosporae were present in the aquatic habitats of the Sunshine Coast region in Australia.

Negative effects of habitat drying and prior exploitation on the detritus resource in an ephemeral aquatic habitat.

Ephemeral aquatic habitats are characterized by cycles of drying and subsequent inundation, and by production of sequential non-overlapping cohorts of organisms. Both processes may alter the quantity or quality of resources, and may therefore affect survival and development of cohorts that subsequently colonize ephemeral habitats. We examined these effects of habitat drying and non-overlapping cohorts on experimental cohorts of the tree hole mosquito Aedes triseriatus, testing specifically whether the value of leaf litter as a food resource is altered by cycles of inundation and drying, or by exploitation by a prior non-overlapping cohort. We created four treatments of leaf litter: (1) no prior cohort, continuously wet; (2) no prior cohort, one␣wet/dry cycle; (3) prior cohort, continuously wet, and (4) prior cohort, one wet/dry cycle, and tested for effects on individual fitness components (survivorship, mean dry mass at, and median days to eclosion) and on population growth (estimated finite rate of increase -λ'). Both resource drying and the presence of a prior cohort negatively affected individual fitness components in tires, increasing days to eclosion, and decreasing mean dry mass at eclosion for both sexes. Resource drying also negatively affected estimated rates of increase (λ') in tree holes. A prior cohort had no significant effects on λ'. These results indicate that intraspecific interactions among mosquito larvae may include amensalistic effects of earlier, non-overlapping cohorts, and that resource drying reduces resource quality. The latter effect indicates that enhanced production of A. triseriatus from recently filled containers is not due to resource drying per se, and may result from more complex community-level effects of habitat drying. Extreme cycles of drying and inundation seem likely to increase intraspecific resource competition among drought-adapted species like A. triseriatus.