Population Dynamics and Diversity of Viruses, Bacteria and Phytoplankton in a Shallow Eutrophic Lake

We have studied the temporal variation in viral abundances and community assemblage in the eutrophic Lake Loosdrecht through epifluorescence microscopy and pulsed field gel electrophoresis (PFGE). The virioplankton community was a dynamic component of the aquatic community, with abundances ranging between 5.5 × 107 and 1.3 × 108 virus-like particles ml−1 and viral genome sizes ranging between 30 and 200 kb. Both viral abundances and community composition followed a distinct seasonal cycle, with high viral abundances observed during spring and summer. Due to the selective and parasitic nature of viral infection, it was expected that viral and host community dynamics would covary both in abundances and community composition. The temporal dynamics of the bacterial and cyanobacterial communities, as potential viral hosts, were studied in addition to a range of environmental parameters to relate these to viral community dynamics. Cyanobacterial and bacterial communities were studied applying epifluorescence microscopy, flow cytometry, and denaturing gradient gel electrophoresis (DGGE). Both bacterial and cyanobacterial communities followed a clear seasonal cycle. Contrary to expectations, viral abundances were neither correlated to abundances of the most dominant plankton groups in Lake Loosdrecht, the bacteria and the filamentous cyanobacteria, nor could we detect a correlation between the assemblage of viral and bacterial or cyanobacterial communities during the overall period. Only during short periods of strong fluctuations in microbial communities could we detect viral community assemblages to covary with cyanobacterial and bacterial communities. Methods with a higher specificity and resolution are probably needed to detect the more subtle virus–host interactions. Viral abundances did however relate to cyanobacterial community assemblage and showed a significant positive correlation to Chl-a as well as prochlorophytes, suggesting that a significant proportion of the viruses in Lake Loosdrecht may be phytoplankton and more specific cyanobacterial viruses. Temporal changes in bacterial abundances were significantly related to viral community assemblage, and vice versa, suggesting an interaction between viral and bacterial communities in Lake Loosdrecht

Forest Plant and Bird Communities in the Lau Group, Fiji

We examined species composition of forest and bird communities in relation to environmental and human disturbance gradients on Lakeba (55.9 km²), Nayau (18.4 km²), and Aiwa Levu (1.2 km²), islands in the Lau Group of Fiji, West Polynesia. The unique avifauna of West Polynesia (Fiji, Tonga, Samoa) has been subjected to prehistoric human-caused extinctions but little was previously known about this topic in the Lau Group. We expected that the degree of human disturbance would be a strong determinant of tree species composition and habitat quality for surviving landbirds, while island area would be unrelated to bird diversity.All trees > 5 cm diameter were measured and identified in 23 forest plots of 500 m² each. We recognized four forest species assemblages differentiated by composition and structure: coastal forest, dominated by widely distributed species, and three forest types with differences related more to disturbance history (stages of secondary succession following clearing or selective logging) than to environmental gradients (elevation, slope, rockiness). Our point counts (73 locations in 1 or 2 seasons) recorded 18 of the 24 species of landbirds that exist on the three islands. The relative abundance and species richness of birds were greatest in the forested habitats least disturbed by people. These differences were due mostly to increased numbers of columbid frugivores and passerine insectivores in forests on Lakeba and Aiwa Levu. Considering only forested habitats, the relative abundance and species richness of birds were greater on the small but completely forested (and uninhabited) island of Aiwa Levu than on the much larger island of Lakeba.Forest disturbance history is more important than island area in structuring both tree and landbird communities on remote Pacific islands. Even very small islands may be suitable for conservation reserves if they are protected from human disturbance

Impact of trampling on the vegetation of sub-Antarctic Marion Island

NatuurwetenskappeBotaniePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Design of the National Flora Monitoring Scheme - Environmental and Nature Quality

Het Landelijk Meetnet Flora - Milieu & Natuurkwaliteit maakt onderdeel uit van het Netwerk Ecologische Monitoring (NEM). Het rapport stelt een ontwerp voor van het LMF - M&N gericht op uitvoering door provincies. In NEM-verband zijn twee meetdoelstellingen aan dit meetnet opgelegd. (1) Het signaleren van landelijke veranderingen in de ecologische kwaliteit van multifunctionele gebieden. (2) Het signaleren van landelijke veranderingen in milieu-aspecten, met name vermesting, verzuring en verdroging, en de gevolgen daarvan voor flora (en fauna). Bovendien moet het LMF - M&N de informatie verzamelen betreffende de algemene plantensoorten van de natuurgraadmeters van het Natuur- en Milieuplanbureau. Aan het meetnet ligt een stratificatiebasis ten grondslag. De dimensionering is statistisch onderbouwd. De methode gaat uit van permanente kwadraten.The National Flora Monitoring Scheme for Environmental- and Nature Quality (LMF - M&N) is part of the Network Ecological Monitoring (NEM). This report documents a design proposal for the LMF - M&N, meant for implementation by provinces. The monitoring scheme has two goals: (1) to indicate national changes in the ecological quality of multifunctional areas and (2) to indicate national changes in the environment, specifically acidification, eutrophication and desiccation, and the consequences of these changes for flora and fauna. The LMF - M&N is also meant for collection of information on the common plant species of the nature indicators of the Nature Policy Assessment Office and the Environmental Policy Assessment Office. The monitoring scheme has a stratification base and the dimensions are statistically underpinned. The method is founded on permanent squares.Milieuplanburea

Design of the National Flora Monitoring Scheme - Environmental and Nature Quality

The National Flora Monitoring Scheme for Environmental- and Nature Quality (LMF - M&N) is part of the Network Ecological Monitoring (NEM). This report documents a design proposal for the LMF - M&N, meant for implementation by provinces. The monitoring scheme has two goals: (1) to indicate national changes in the ecological quality of multifunctional areas and (2) to indicate national changes in the environment, specifically acidification, eutrophication and desiccation, and the consequences of these changes for flora and fauna. The LMF - M&N is also meant for collection of information on the common plant species of the nature indicators of the Nature Policy Assessment Office and the Environmental Policy Assessment Office. The monitoring scheme has a stratification base and the dimensions are statistically underpinned. The method is founded on permanent squares.Het Landelijk Meetnet Flora - Milieu & Natuurkwaliteit maakt onderdeel uit van het Netwerk Ecologische Monitoring (NEM). Het rapport stelt een ontwerp voor van het LMF - M&N gericht op uitvoering door provincies. In NEM-verband zijn twee meetdoelstellingen aan dit meetnet opgelegd. (1) Het signaleren van landelijke veranderingen in de ecologische kwaliteit van multifunctionele gebieden. (2) Het signaleren van landelijke veranderingen in milieu-aspecten, met name vermesting, verzuring en verdroging, en de gevolgen daarvan voor flora (en fauna). Bovendien moet het LMF - M&N de informatie verzamelen betreffende de algemene plantensoorten van de natuurgraadmeters van het Natuur- en Milieuplanbureau. Aan het meetnet ligt een stratificatiebasis ten grondslag. De dimensionering is statistisch onderbouwd. De methode gaat uit van permanente kwadraten