There has been minimal synthesis of the impacts of water-quality degradation from agriculture on freshwater ecosystems in northern Australia. The present study conceptualises the spatial and temporal processes driving water-quality pressures in Australia’s Great Barrier Reef catchment area, with associated ecological impacts. Hydrology mediates the timing and scale of pollutant delivery to freshwater ecosystems, and the risk periods and specific nature of water-quality impacts can differ markedly from those most affecting downstream marine environments.

Environmental (e)DNA sequencing can be used to identify entire biological communities in a rapid and inexpensive way, and has the potential to benefit aquatic biodiversity surveys. The aim of this review is to provide guidance to non-geneticists regarding eDNA sequencing for biological surveys and to outline the requirements that need to be considered before the technique can be incorporated into aquatic biomonitoring programs.

We compared the effects of water allocations, conservation and climate change scenarios on economic returns from irrigation. Land use had the greatest economic returns, but land area suitable for irrigation rather than irrigation water itself was the major limitation. Annexing land for freshwater conservation values had only small effects on economic returns, suggesting that conservation and agricultural development are not necessarily antagonistic goals.

Freshwater sediments harbour minute but diverse microscopic fauna, dominated by rotifers and nematodes. In our research we try to define occurrence and vertical distribution of these organisms in a specific karst sediment – tufa. Deeper parts of sediments are mostly inhabited by surface fauna that is morphologically pre-adapted to life within sediment interstices and this seems to be general rule in freshwater ecosystems.

We surveyed Tibetan streams between 4459 and 5062 m above sea level to obtain data on densities, habitat preferences, feeding selectivity and food web position of the stone loach Triplophysa; some of the world’s highest living and ecologically least studied fish. Densities were highest near lakes (1.6 individuals m^–2) and decreased with altitude and glacial influence. Triplophysa was omnivorous, but was always at the top of the food web.

Using towed imagery in turbid waters enabled a rapid, large-scale survey that observed severe thermal coral bleaching in March 2013 off Onslow, north-western Australia. Despite predominance of bleaching resistant species we found over 50% of all corals bleached in 10–15-m water depth. Recurrent heat stress is assumed to have structured the local coral community, eliminating thermally vulnerable species.

We investigated the potential for zooplankton to emerge following inundation of dry soils on the lower Waikato River floodplain, New Zealand. Our findings indicate that scrub and forested floodplains can be important areas for large-bodied zooplankton production, and that maintaining vegetative heterogeneity on floodplains may promote trophic subsidies for migrating juvenile fish as floodwaters subside.

Relationships between productivity and population biology (abundance, individual size, growth rates, longevity, secondary production and turnover rates) of two intertidal gastropods of different trophic levels, the herbivorous Cerithium atratum and the scavenger Nassarius vibex, in a sandflat environment were investigated. The life-history traits of the gastropod species responded to different trophic levels. Herbivores had higher abundance, growth and production efficiency than did scavengers.

Summary.  American eels commonly occupy bays and estuaries of the southern Gulf of St Lawrence in both summer and winter. Winter use of this region is perplexing because seawater under winter ice is often cold enough to freeze and kill fish. We demonstrate that American eels lack antifreeze proteins, and instead, find thermal protection in mud burrows that are warmer than the overlying water.

Significant regression relationships existed between carbon biomass and cell abundance for phytoplankton based on net samples from the Yellow Sea and the East China Sea. We established carbon biomass : cell abundance relationships for all phytoplankton cells, diatoms, dinoflagellates and each dominant genus. We suggest using these relationships to improve standing stock research in marine ecology.

Status and trends of larval populations of Petromyzon marinus were studied in north-western Spain by annual electrofishing surveys (2007–2011) and data from other European regions were compiled. The largest populations and the main fisheries of this threatened species are located in south-western Europe. Signs of population increases were registered; however, more data are needed to confirm a possible overall recovery.

Human disturbance of the sea–mangrove connection is currently hampering the natural hydrodynamics of both mangroves evaluated in this study (i.e. Conchas and Malanza). This, and the presence of the Mozambique tilapia, as elements of ecological disruption, may act as limiting factors for the potential biodiversity of the systems.

In many coastal areas around the world freshwater inflows are threatened. The San Antonio Bay System (USA) is of particular interest because it is the winter home of the endangered whooping crane. Organisms of higher trophic levels might be deleteriously affected by reduced inflows because our study suggests that shifts in phytoplankton composition and location of productivity maxima will likely result from lower inflows.

Regulated rivers lack large discharge events or floods, which play a critical role in controlling fine sediment deposition and the maintenance of healthy in-channel condition. Five large environmental floods were released into the regulated Snowy River to mitigate fine sediment accumulation within the river channel. This article identifies the effectiveness of multiple intra-annual floods of various magnitudes at mobilising fine sediment within the regulated river channel.

In this study, we investigated spawning responses of Australian grayling to environmental flows over 2 years in three coastal rivers. Spawning activity was highest during within-channel flow pulses, especially during periods of targeted managed flows. Peak spawning occurred in late autumn and was positively related to flow duration. Our study demonstrates the importance of quantifying flow-ecology relationships by targeted monitoring and research in order to develop appropriate flow regimes.

The present study proposes otolith marking as a method to unequivocally detect selected pre-flexion fish larvae in the digestive tracts of their fish predators, even several hours after their ingestion. Mark detection levels were high (>65%) even after 9 h from prey ingestion. This constitutes a single and inexpensive technique that could be applied in both laboratory and field experimental studies of predator–prey interactions.

Management of invasive species largely focuses on early detection and eradication; however, once established, invaders could also be controlled by exploiting local adaptations in native species. The present research demonstrated that dwarf galaxias (Galaxiella pusilla), a threatened Australian freshwater fish, has adaptations to habitat drying that could underpin efforts to control invasive eastern gambusia (Gambusia holbrooki) within critical habitats.

Analysis of COI sequences of the shrimp Caridina cantonensis from streams in Hong Kong showed that populations from different streams are genetically distinct, whereas the genetic diversity within each stream is very low. The results suggested that a substantial amount of biodiversity might have been lost during the development of the city over the past century.

The present study reveals the occurrence of multiple paternity in the bull shark (Carcharhinus leucas) showing high paternal skew. These results tend to support the hypothesis of convenience polyandry. This study contributes to a better understanding of this species reproduction and are important for both shark conservation and management plans.