Freshwater pollution is an actual and relevant issue that requires efficient monitoring tools. For this scope, biological models are researched for evaluating ecological stresses and to provide water-quality status. In this context, Hydra vulgaris may provide a valid contribution, especially for early warning systems, owing to its regenerative ability and standardised morphological biomarkers producing economical, rapid and simple assays.

Understanding route selection by silver eels during their downstream spawning migrations is important for assessing migration success and developing conservation strategies. On the basis of acoustic camera data and replicated mark–recapture experiments, we determined that silver eel route selection at a water-regulating weir was passive and strongly related to the proportion of total river flow to different routes.

Studies of Odonata diversity in the Neotropical region are scarce. Neotropical savanna in Colombia is an ecosystem strongly threatened and rapidly being transformed by human population growth. This study examined the how the richness, composition and abundance of the suborders Anisoptera and Zygoptera are affected by altitude and habitat (lentic or lotic) in the savanna of the Colombian Orinoquía region. The results indicate that only Anisoptera was affected by altitude, and not by habitat.

A better understanding of the stock structure and migratory trends of Pacific cod in South Korea is needed to sustainably manage the fishery. Here, analysis of the elements incorporated into fish otoliths (‘ear stones’) from the environment was used to determine how many distinct stocks of Pacific cod reside around the Korean Peninsula. The elemental signatures from different parts of the otolith were also compared to assess whether fish may return to the same spawning region from which they hatched.

Ita Lake in south-west New South Wales, Australia, is an inland lake that has been dry for 10 years. Through a glasshouse experiment, we watered soil seed bank samples and found that the seed bank was still viable. In addition, intensive land uses, such as ploughing, affected the number of seeds that germinate and the amount of water determined which species emerged. These results will direct the restoration management and prioritisation of environmental water.

This study tested whether the use of copper-free seahorse-friendly net material has any effect on populations of the Endangered seahorse H. whitei. Seahorse populations on a net constructed of seahorse-friendly net material were compared with those on regular copper-braided nets, and panels of both material types were installed at two sites, with comparisons of seahorse density across net types. Net material had no effect on the density or population abundance of seahorses on pre-existing or installed panels of net.

Asian swamp eels are invasive in the United States and difficult to document because they remain hidden in underground burrows most of the time. We used leaf-litter traps that were effective at capturing juveniles of this species. This research was able to use information from juvenile captures in one population near Atlanta, Georgia, to show that this species is more widespread than previously known.

This study examined how the community of key primary producers in Moreton Bay (diatoms) has altered in response to significant land-use changes experienced in the adjacent Brisbane River Catchment. The results show that since the mid-20th century, and coincident with an acceleration of land-use change, the relative abundance of diatoms that primarily inhabit the water column has increased, whereas that of those that inhabiting the sediments on the sea floor has declined.

Fish fin tissue is a suitable non-lethal surrogate for muscle tissue in food web studies. We compared δ¹³C and δ¹⁵N values of caudal fin tissue and dorsal muscle tissue from three species of Australian fish (Cyprinus carpio, Macquaria ambigua and Nematalosa erebi) and established tissue conversion models. Fin tissue is a reliable proxy for muscle tissue, allowing for non-lethal collection of samples for stable isotope analysis.

Etelis coruscans, commonly known as onaga, is a member of the commercial deep-water handline fishery of the Hawaiian Islands and is found throughout the Indo-Pacific. Bomb radiocarbon dating was used to validate the otolith age reading criteria and the lifespan was found to be at least 50 years, exceeding previous estimates by three to fivefold. E. coruscans appears to exhibit differences in growth between sexes, and individuals may mature at a greater age than most other deep-water snappers.

Because of their generally restricted distribution, the endemic Labeobarbus species in Lake Tana are vulnerable to anthropogenic pressures. Although successful conservation of these species demands knowledge of life history traits, such studies are non-existent. In this study, age, natural mortality and length–weight relationships of Labeobarbus species were determined. Three growth models were evaluated to select the model that best fits the length-at-age data, and growth rates were estimated using the best-fitting model.

The introduced Lernaea species in Australia has been poorly studied, with nearly all reported Lernaea infections referred to as L. cyprinacea without genetic characterisation. This study compared the sequences of Lernaea species collected from four native and three introduced fish species with GenBank sequences. For the first time, we have genetically identified the Lernaea species found in the Murrumbidgee catchment as L. cyprinacea.

The backbones of skates and rays, like sharks, have concentric bands that have been used to determine age. Here, we conclude that vertebral shape and number of bands vary within the backbone of an individual. This suggests that the concentric bands are related to body growth rather than to age.

Using molecular markers, we explored the abundance and distribution of autotrophic microbial communities residing in the benthic zone of a pristine pond. RuBisCO genes were detected across all the pond, and interesting correlations with sediment geochemical properties were found, highlighting the genetic potential of these benthic microbial communities in terms of autotrophy based on the Calvin–Benson–Bassham cycle.

Ear stone chemistry provides powerful insights into the lives of fish. We investigated the influence of both physiological and the environmental factors on elemental and isotopic signatures in the ear stones of an iconic fishery species, snapper (Chrysophrys auratus). We identified chemical markers, which displayed potential as physiological proxies, in addition to environmental proxies.