We studied changes in geochemical variables in the middle section of Río de la Plata estuary during the 2009–2010 ENSO event. Protein, organic matter, chlorophyll-a and phaeopigment content of surface sediments were correlated with increased freshwater input associated with high total monthly rainfall. River flow was 5-fold larger than historical levels, which led to decreased salinity and increased geochemical levels.

The unique lifecycle of diadromous fishes enables them to migrate between a range of aquatic environments; however, these migrations also place them at risk from a range of anthropogenic factors. Despite these apparent risks, little information is available on the lifecycle of many Australian species and this review investigates new and improved research tools that could be used to address information gaps and enable appropriate management of these species.

Information concerning the drivers of seasonal variation in algal biomass in subtropical mountain streams is limited. We found that episodic typhoon-induced floods, and the levels of agricultural activity and riparian vegetation, shape the seasonal variations in algal biomass in subtropical mountain streams. This study has important implications for establishing ecological standards for stream, riparian and watershed ecosystem management.

The choice of appropriate conservation strategies for reef fishes depends on their mobility, degree of site fidelity and residence times. Here we report the results of a small-scale mark–recapture and resighting study conducted to investigate the spatial dynamics of the Argentine sandperch, Pseudopercis semifasciata. High site fidelity and long residence times in the reefs suggest that relatively small reserves (in the order of a few kilometres) could be effective at protecting this species within the northern Patagonian gulfs of Argentina.

Organic carbon is a key component of riverine ecosystems. During a period of extreme flow variability in the the Lachlan River catchment in 2010–2011, analysis of organic carbon showed that flow variability is one of multiple factors that influence organic carbon in rivers. These findings have implications for the future management of rivers in Australia and elsewhere.

We investigated, for the first time, the population genetic structure and evolutionary history of Scyllarides brasiliensis. High genetic homogeneity was observed along 2700 km of south-west Atlantic coast, suggesting levels of gene flow promoted by the high dispersal potential of its larvae. This result has important implications for the conservation of the most commercially important slipper lobster species in South America.

The determination of organic phosphorus compounds in lake sediments can provide information on the potential for internal phosphorus loading. Several potentially bioavailable phosphorus compounds in the bottom sediments of Lake Okaro, New Zealand, were identified that were likely to contribute to recycling of phosphorus from the sediment to the water column. The time scales on which these compounds were recycled indicate that high internal phosphorus loadings may persist for decades, potentially hindering restoration efforts.

Macrobrachium acanthurus is a common amphidromous shrimp in estuaries and rivers of the western Atlantic; however, many aspects of the population dynamics of this shrimp are still unclear. This study shows that the reproduction is seasonal and females do not migrate down river towards the estuary to hatch larvae. Also, population-level reproductive parameters, including size at first maturity and sex ratio, vary considerably at moderate spatial scales throughout the year.