Draft Genome Sequence of Strain HIMB100, a Cultured Representative of the SAR116 Clade of Marine Alphaproteobacteria

Strain HIMB100 is a planktonic marine bacterium in the class Alphaproteobacteria. This strain is of interest because it is one of the first known isolates from a globally ubiquitous clade of marine bacteria known as SAR116 within the family Rhodospirillaceae. Here we describe preliminary features of the organism, together with the draft genome sequence and annotation. This is the second genome sequence of a member of the SAR116 clade. The 2,458,945 bp genome contains 2,334 protein-coding and 42 RNA gen

Draft genome sequence of strain HIMB100, a cultured representative of the SAR116 clade of marine Alphaproteobacteria

Strain HIMB100 is a planktonic marine bacterium in the class Alphaproteobacteria. This strain is of interest because it is one of the first known isolates from a globally ubiquitous clade of marine bacteria known as SAR116 within the family Rhodospirillaceae. Here we describe preliminary features of the organism, together with the draft genome sequence and annotation. This is the second genome sequence of a member of the SAR116 clade. The 2,458,945 bp genome contains 2,334 protein-coding and 42 RNA genes

Nitrogen response of natural phytoplankton communities: a new indicator based on photosynthetic efficiency Fv/Fm

The availability of the primary limiting nutrient plays a major role in driving the productivity, biomass and community composition of coastal phytoplankton, but there is an ongoing challenge to define the relationship between nutrient enrichment and phytoplankton response. This study explored a new indicator (N95) for quantifying nutrient response in natural phytoplankton communities. In this study, N95 specifically represented the required nitrogen addition (normalised to chlorophyll a) for the sampled phytoplankton population to reach 95% of nitrogenreplete photosynthetic efficiency. To calculate N95, an asymptotic model was applied to measures of phytoplankton photosynthetic efficiency (F-v/F-m) taken after 24 h incubations under a range of nitrogen enrichment treatments. Applying the method in an Australian subtropical bay, Moreton Bay, nitrogen response was lowest nearshore and high, yet variable, offshore. This pattern reflected the ambient nutrient gradient of declining concentrations with distance offshore. A Moreton Bay-specific threshold in phytoplankton nutrient response was identified at the ambient dissolved inorganic nitrogen concentration of 2 mu mol l(-1), above which the response to nitrogen enrichment did not increase for 82% of samples. Advantages to measuring N95 were that incubations were simple to set up, incubation period was short, and F-v/F-m measures were simple to make. This approach advances options for using F-v/F-m measures to assess phytoplankton nutrient response and provides a new and sensitive biological indicator applicable to long-term water quality monitoring programs, relevant to parameterising ecological models and supporting decision making on nutrient management

Beyond proximity: How subjective perceptions of enablers and constraints influence patterns of blue space recreation

Recreational blue space use generates important social benefits, that are supported by proximity to coastal and freshwater spaces. Yet, little research has explored different patterns of blue space use and how this is influenced by subjective perceptions about blue spaces. Here we draw on data from a representative survey of residents of South East Queensland (Australia) (N = 3128) to develop a typology of blue space use and quantify the frequency with which different types of blue spaces are used. We identified five distinct groups of blue space users: three frequent use groups, and two low use groups. Greater proximity to coastal areas which permit diverse types of activities supported all three frequent use groups, while greater distance from the coast limited low use groups. However, subjective perceptions about enablers and constraints also influenced use. For example, frequent exercisers and regular users do report constraints, but these tend to be related to place (suggesting structural constraints), and these groups also report high motivations. Non-users represented 13% of the sample, and reported low motivation, and high intrapersonal constraints such as not-belonging. Our findings suggest that behaviour patterns in and around waterways reflect both perceptions of the environment, and individual-level constraints that may transcend environmental context.</p

Nutrient metrics to compare algal photosynthetic responses to point and non-point sources of nitrogen pollution

Point- and non-point source nutrients are likely to have different ecological impacts in receiving waters, due to differences in the concentration and proportions of nutrient fractions. However, the direct comparison of their ecological impacts in receiving waters has barely been quantified. We undertook algal bioassays with algal communities from river sites and showed that there was a photosynthetic yield (Fv/Fm) response to nutrient enrichment when river nutrient concentrations were relatively low, but not at higher nutrient concentrations. To combat this variability in the photosynthetic state of algae, we developed a standardized algal bioassay (3-day), using a cultured species of algae which was starved of nitrogen, to compare the photosynthetic response to three nitrogen sources: treated wastewater, aquaculture farm discharges, and soil erosion-derived nutrient sources. This study showed that the nutrient parameter that had the highest correlation with algal photosynthetic response was total dissolved nitrogen (TDN), i.e., the sum of dissolved inorganic and organic nitrogen, rather than dissolved inorganic nitrogen alone. This was true across all three nutrient sources (R2 = 0.58–0.78). Additionally, the same concentrations of TDN from soil erosion-derived and aquaculture samples resulted in a significantly higher algal photosynthetic response, compared to the treated wastewater. This indicates that TDN from soils and aquaculture farms was significantly more bioavailable to the cultured algae than treated wastewater. When a range of parameters were correlated with algal responses, organic and inorganic nutrients, and organic carbon were the parameters that had the highest explanatory power for soil erosion-derived and aquaculture samples (R2 = 0.75–0.87). The importance of organic compounds in these equations points to the potential of microbial transformation of organic nutrients into more bioavailable forms during the 3-day bioassay. This highlights the need to understand the relationship between algal and microbial communities in natural systems for nutrient source impact assessment. This study provides an improved understanding and metrics for comparing the algal growth response to different nutrient sources

Science to Support Management of Receiving Waters in an Event-Driven Ecosystem: From Land to River to Sea

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Flow events drive patterns of phytoplankton distribution along a river-estuary-bay continuum

Freshwater flow events drive phytoplankton productivity in subtropical coastal river systems. However, few studies have the necessary temporal and spatial resolution to fully characterise the effect of events on the distribution of phytoplankton across the full river-estuary-bay continuum. The present study characterised the response of phytoplankton to high-flow events in an Australian subtropical system; and identified the primary drivers of this response. During high-flow events, the concentration of phytoplankton chlorophyll a (Chl a) initially declined in the estuary, a response primarily driven by the shortened water-residence time. In the bay, phytoplankton growth in the near-shore zone was light limited; however, nutrients stimulated phytoplankton growth on the seaward edge of the river plume. During the post-high-flow phase, the concentration of Chl a in the freshwater reaches peaked downstream, where catchment-derived nutrients accumulated. In the estuary, elevated nutrient loads stimulated phytoplankton growth upstream and downstream of the light-limited zone. In the bay, nitrogen availability declined, and Chl a declined with an increasing distance offshore. The phytoplankton response to events documented in the present study can be used to identify when and where phytoplankton in subtropical systems may be strongly influenced by changes in the magnitude of nutrient, sediment and freshwater loads associated with high-flow events which result from anthropogenic pressures within the catchment