This study aimed to better comprehend the reproductive biology of the genus Potimirim. We analysed the sexual systems of P. brasiliana and P. potimirim under the hypothesis that both shrimps also have sequential protandry. Both species are gonochoric and our findings led us to conclude that there is no common shared sexual system pattern for this genus.

The knowledge of reproductive parameters is essential to develop effective management and conservation plans. The present study provides the first information on the reproductive biology of an abundant trawl by-catch skate, Bathyraja magellanica, in the south-western Atlantic. Our results indicated that this species has a low reproductive efficiency, suggesting that populations should be monitored closely.

Tropical insular hydrosystems are dominated by amphidromous species whose life cycle remains poorly known. Otolith microstructure and composition revealed for the first time the amphidromous life traits for two ancestral gobioids, Rhyacichthys guilberti and Protogobius attiti, and a shorter pelagic larval phase for the widespread species. This suggests that factors other than the pelagic larval duration control endemism and dispersal processes.

Algae growing in intermittently flowing streams recolonise via regrowth from dry cells and the arrival of drifting cells. These recolonisation processes may influence algae until spring but in most streams, the duration of influence will be shorter. Because flow regimes and algal composition vary among streams, the effects of flow regulation also vary, making them difficult to predict.

Given the behavioural variability among species, predatory species have distinguishable effects on lower trophic levels. Using experimental in situ mesocosms, we show that hyperbenthic and pelagic predators regulate different planktonic copepods in shallow temperate estuaries. Understanding the varied effects of predator species on lower trophic levels has implications for biodiversity conservation.

Common carp (Cyprinus carpio) is a highly invasive fish in several freshwater systems worldwide, including wetlands of the Murray–Darling Basin (south-eastern Australia). A 2-year field experiment in a wetland of the River Murray evaluated the species effects on turbidity, aquatic macrophytes, zooplankton, benthic invertebrates and fish. Within 1 year, there was a shift from clear- to turbid-water state and this was related to a carp biomass level lower than previously reported for Australia.

The nature of the link between periphyton biomass and macroinvertebrate diversity in streams remains unclear, which may be due in part to the growth form of plants. We examined this relationship in 24 streams of Cantabria, Spain, and found no link between periphyton biomass and macroinvertebrate diversity, but the relationship was underpinned by specific links with the growth form of periphyton. These findings suggest that bioassessment programs may benefit from the addition of periphyton growth-form assessment, rather than focussing specifically on biomass measures.

Unobserved by-catch is often poorly understood and rarely accounted for in fisheries management. Our assessment of protected and vulnerable species by-catch in an Australian fish trawl fishery showed that by-catch reduction devices were limited in their efficacy and unaccounted by-catch was substantial. We propose gear modifications and the use of in-trawl video cameras alongside observer coverage to improve by-catch estimates and mitigation.

Marine sponges are capable of metal bioaccumulation but the mechanisms are not well understood, in particular whether the capacity to accumulate metals is due to the sponge or the microbes they harbour. We discovered that a rod-like bacterium is responsible for high molybdenum concentrations a tropical sponge. We speculate that this potentially new species of bacterium is involved in metabolic processes and provides a step towards understanding host–microbe relationships.