Marine and Freshwater Research
Volume 67
Number 11 2016
Factors such as areas of unsuitable habitat, physical geography, ocean currents and sea surface temperatures explain many features of the phylogeography of the coasts of south-eastern Australia. More research is needed to explain how genetic variation can remain partitioned after barriers to gene flow are dissolved, to understand the phylogeographic effects of biotic interactions and to elucidate the cause(s) of population genetic instability frequently observed within both marine and estuarine species.
We contrasted dietary ecology of two river turtles across four monsoonal river systems of the Kimberley Plateau in Western Australia. The study sites crossed a rainfall gradient and variable land use practices. The effects of biological invasion (short term), land use (medium term) and climate change (long term) affect the foraging habitats of turtles in these rivers. The dietary results offer a benchmark in before–after studies as invasive cane toads are expected to reach the study sites in 1–2 years.
A novel approach was developed for observing attempted predation on live juvenile spiny lobster (Jasus edwardsii) by presenting the lobster in a transparent container that was lit with infrared light to enable continuous monitoring, by video recording. This technique can be used to provide valuable information on overall relative predation pressure from comparative locations and habitats, as well as identify potential predators.
Marine subsidies represent a key element for the maintenance of biodiversity and functioning of sandy beaches. The colonisation patterns of macroinvertebrates associated with detached seaweed and mangrove propagules was investigated on Atlantic beaches. Marine subsidies were promptly invaded by a wide range of species, but a directional replacement was not detected. The results suggest that the colonisation process is driven by organic-debris characteristics and biological strategies of the species.
Functional approaches improve the understanding of how ecological communities respond to environmental changes. We compared functional diversity of aquatic insects among natural ponds, and organic and conventional rice fields, and the highest functional redundancy and richness were observed in natural ponds. As organic rice fields showed some functional similarity with natural ponds, the ecological benefits of organic production are highlighted.
This study identified sulfidic sediments in reaches of an inland freshwater river in south-eastern Australia. Sulfidic sediments preferentially accumulated where coarse sandy bed material was found. Conversely, limited sulfidic sediment accumulated where bed material was clay or silt dominated. Sulfidic sediment accumulation was not limited to lower-energy parts of the channel highlighting the dynamism of the system.
Hydrological regimes are important drivers of community dynamics in intermittent streams. Investigation of stream fish communities from north Texas, USA, before, during and after a prolonged drought disturbance revealed that drought had significant impacts on fish abundance and diversity and population and community recovery. Continued alteration of stream habitats and changes in global climate may intensify future drought disturbances and have potentially large impacts on freshwater biodiversity at multiple scales.
Monthly dynamics of eukaryotic phytoplankton diversity and community structure in a freshwater reservoir were studied using small subunit ribosomal RNA (SSU) pyrosequencing. Molecular analyses represented a typical pattern of seasonal phytoplankton succession in temperate regions and this was denoted predominantly by diatoms, dinoflagellates, cryptophytes and chlorophytes. This work emphasises the importance of pyrosequencing in monitoring phytoplankton communities.
Predator–prey mass ratio (PPMR) and trophic positions of the pelagic food web in the East China Sea and the Sea of Japan were estimated by using the stable isotope ratios (δ15N). The PPMRs based on additive and scaled models were respectively 5032 and 3430. The comparatively high PPMRs could reflect low ecosystem transfer efficiency and high metabolic rate.
Recent research has determined that bacteriophages (viruses that infect bacteria), play a crucial role in environmental processes. However, phage diversity is understudied in freshwater environments. The current study utilises data collected from extracting DNA directly from the environment, and begins to examine the phage community in Lake Michigan. The research finds that, within the lake, phages are highly diverse, but also highlights the importance of combined methodological approaches.
Baños tarn is a low-altitude Pyrenean glacial lake with both geothermal and surface influxes, and significant local anthropic stressors. Hydrological changes affecting lake tributaries are the foremost factors driving seasonal changes in the ionic composition of the lake, determined by a slightly alkaline pH and a medium–high ionic content, whereas resuspension of organic matter and nutrients trapped in floor sediments by a long history of untreated waste water input is the main nutrient source for the Baños tarn water mass.
This paper reports observations of turbidity currents and internal waves made in 2012–13 in Lake Ohau, New Zealand. Sediment input from river inflow occurs throughout the year but exhibits strong seasonal variation. We utilise these observations to establish a conceptual model to explain the observed infill stratigraphy in Lake Ohau and guide interpretation of the longer sedimentary record.
Accurately detecting the presence of threatened species is vital for effective conservation management. Investigation of the detection power of six sampling methods for the endangered Macquarie perch found that fyke nets were far superior to all other methods. Some commonly used generic sampling methods had low detection efficiency, with such false negatives having serious implications for conservation management.
This study aims to understand the biological drivers of KwaZulu–Natal Bight, South Africa, which until now were believed to be oceanographic. Particulate material and zooplankton were collected from marine and riverine environments. Rivers were extremely important for biological communities close to shore in the wet season. In the dry season and offshore this was not the case. Highlighting the role of terrestrial particulate matter to the marine environment.
This study presents an important first description of spatio-temporal spawning patterns of two riverine Macquarie perch Macquaria australasica populations in south-eastern Australia. Spawning intensity was highly variable between sample sites, and displayed a strong positive association with water temperature. Our results provide opportunity for further testing of the environmental effects, habitat associations and subsequent management options aimed at enhancing spawning of this endangered species.
The knowledge of the distribution of substrate sediments is crucial to understanding and managing wetland aquatic bodies. We tested the ability of a hydroacoustic system to discern and map substrates in three rivers from the largest wetland in Jamaica, by using various classification algorithms and interpolation methods. At a lower spatial resolution, comparable maps were obtained by interpolating discrete sample points acquired from grab samples.