Marine and Freshwater Research
Volume 70
Number 11 2019
The Ramsar Convention is the world’s most important international wetland initiative. In recent years, its tools of implementation have been called into question. One of those is the Montreux Record (MR), a kind of ‘in-danger list’ for at-risk wetlands. This paper provides the first comprehensive academic analysis of the MR and makes suggestions for how the system could be improved.
Eggs and larvae of three fish species were exposed to different elevated fluid shear levels at a high-velocity jet in a laboratory flume. Eggs were very susceptible to mortality at low strain rates, whereas larvae were typically most vulnerable at higher strain rates and at younger ages. Knowing such thresholds can assist designing and operating river infrastructure to protect fish.
One hectare of wetlands dominated by tea trees (Melaleuca) has the potential to remove 400 kg of nitrogen per year. The capacity of these wetlands to remove nitrogen is mostly driven by how much nitrate is in the water. We should protect, restore and create new wetlands for improving water quality within tropical catchments.
Phosphorus (P) in the environment is present in different forms, some more available to organisms than are others. We found that the most bioavailable form of P, orthophosphate, is also the dominant form of P in the Lower Murray River region. Although river red gum leaf litter contains a large amount of organic P, this is quickly released and converted to bioavailable P on wetting. The findings have implications for the management of floodplain wetting events.
This study provides valuable information for improving programs of translocation, restocking and captive breeding, for both the wild barramundi fishery and the aquaculture industry. The results point to the existence of two distinct genetic stocks and a central region of admixture, located in an area where a historic land bridge once connected northern Australia with Papua New Guinea. Understanding the population structure of fish stocks is important for the sustainable exploitation of fisheries and the collection of founder broodstock for aquaculture.
Considering the importance of chemical risk assessment in fish for human consumption set by international legislation, the aim of this study was to evaluate the safety of Ohrid trout from Lake Ohrid for human consumption. Specifically, Pb and Cr concentrations in muscle were below the thresholds set by European Union (EU), Food and Agriculture Organization of the United Nations and World Health Organization legislation, whereas the concentration of Cd in muscle tissue was above the critical limit suggested by EU legislation.
In this study we investigated whether trophic interactions between a native muricid gastropod and an invasive barnacle may have facilitated the latter’s invasion. We found that Trophon geversianus primarily consumes mytilids, but also consumes Balanus glandula at low rates. Gastropods would be exerting little top-down control on B. glandula on Patagonian rocky shores, a harsh environment where desiccation stress is extreme.
Brown macroalgae belonging to Fucales are canopy-forming organisms that urgently calls for research to fill knowledge gaps and support effective measures for protection. We characterised the molluscan assemblages associated with three Cystoseira taxa (Fucales) and tested whether different congeneric taxa may syntopically support a different biota. The present findings shedded light on the importance of such habitat-forming macroalgae in structuring the local infralittoral invertebrate biodiversity and as a nursery for species-specific associated molluscs.
Experiments were conducted to evaluate the effects of El Niño on morphofunctional changes to the phytoplankton community in tropical ecosystems. In semi-arid reservoirs, the El Niño event decreased the relative biomass of filamentous cyanobacteria and favoured central diatoms because of changes to sulfate concentrations.
The Daly River, a large tropical river in northern Australian, has a pronounced seasonal pattern of sediment concentrations and water clarity. The wet season has high flows and high concentrations of sediments with poor water clarity, whereas dry-season low flows are clear with low sediment concentrations. The total amount of sediment being carried by the river every year is low compared with other Australian catchments that have catchments more affected by human activity.
This study investigated differences in the nitrogen removal processes (nitrification and denitrification) in the rhizosphere soil of Typha orientalis and Phragmites australis in a horizontal surface flow constructed wetland in winter. We further investigated the relationships between the nitrification and denitrification processes and the abundance of functional microorganisms, and analysed the effects of environmental factors on microbial abundance. The findings of this study could help increase nitrogen removal efficiency in constructed wetlands in winter.
The distribution of functional traits revealed a clear temporal variation at different water depths. The colonisation pattern at 1- and 2-m depths were significantly different from those at 3.5 and 5 m. The functional diversity generally showed similar temporal variation as functional traits, thus 1 to 2 m may be the optimal sampling strategy for bioassessment using functional traits.
The passage efficiency and flow structure of the diagonal brush fish pass was investigated at the İncirli Small Hydropower Plant, which is located in the Eastern Black Sea region in Turkey. The passage efficiency of five fish species was calculated to be 67%. The brush fish pass provides passage for small-bodied fish.
Two species of killifishes from Lake Salda, Turkey, were studied to characterise their reproductive characteristics. The results show that they reproduced synchronously from April to September. This synchronous pattern of reproduction for genetically similar species could lead to the development of hybrids, which could affect monitoring and conservation methods. Nematode infection was also found to significantly decrease reproductive parameters.