We provide a comment to highlight and correct some errors contained in a recently published paper on the community composition of fishes in dry-land rivers in north-western Zimbabwe. With its errors, inadequate sampling and data collection, and the superficial and confusing data analysis, this paper cannot be said to have advanced our understanding of the fishes of Zimbabwe.

The biology of angel sharks (Squatina sp.) and sawharks (Pristiophorus sp.) was assessed using animals captured in south-eastern Australia. Data indicated that there are morphological features that allow the separation of concurrent species, and we provide ratios that allow accurate predictions of total lengths from truncated specimens.

This paper investigated population genetic structure of Euastacus armatus across its present range to provide insight into recovery potential in the species. We revealed low levels of gene flow sufficient to maintain population sizes and genetic diversity, but also local genetic structuring and limitations on dispersal were evident. These findings forecast limited potential for natural recolonisation and recovery following the decline of local populations.

The size-specific and composition relationships between zooplankton and phytoplankton were evaluated in a large subtropical lake. The zooplankton to phytoplankton biomass ratio was usually very low, indicating a weak top-down control; however, the strength of this interaction varied with zooplankton composition and temporal or spatial variability of the environmental factors. The environmental variability induced by wind action and diversification of niches played a substantial role in the capacity of zooplankton in controlling the phytoplankton biomass.

Introduced algae have the potential to substantially modify native communities. The present study describes the distribution and density of Sargassum muticum in shallow subtidal areas in Galicia (north-western Spain) and shows what factors might be behind its establishment. The study also demonstrates the usefulness of zero-inflated models to assess early and mid-stages of a seaweed invasion.

The Pacific oyster is a widely spread invasive species globally, with a great influence on native biodiversity and ecosystem functioning. How future climate will influence further spread and establishment of the species in the outer range of its present distribution is important knowledge to assess future risks and to plan mitigation actions. The present paper explores how future climate will affect the species spreading potential at its northern distribution limit in a temperate ecoregion, by three-dimensional oceanographic simulations using different climate scenarios.

In the present study we assessed the origin of introduced populations of Mytilus galloprovincialis in the north-western Pacific, providing new insight into the biogeography of M. galloprovincialis. The results showed that populations of M. galloprovincialis in the north-western Pacific were introduced from the middle Mediterranean Sea and that the Dalian population was the first colonised population in Chinese coastal waters.

The present study used the global and local regression models to explore the relationships between walleye abundance (Stizostedion vitreum) distribution and habitat variables in Lake Erie. The relationship was found to vary spatially and was scale-dependent. Our study highlights the importance of considering local regression. It also provides extra knowledge on zonation of species-habitat relationships and validates walleye management units to a degree.

The present study investigated spatiotemporal variation of key prey fishes in the Murray Estuary and Coorong. Small-mouth hardyhead dominates the South Lagoon, and sandy sprat and Tamar goby occur in the North Lagoon at a low abundance, but both are absent from the South Lagoon. The change of prey-fish abundance is mainly driven by salinity. The study has improved our understanding on the dynamics of small-bodied fish species and key environmental factors regulating fish distribution.

We tested the hypothesis that the hydrological regime of large rivers affects the structure of invertebrate communities and food webs, by investigating two lakes with different connectivity to the fluvial system and over three hydroperiods. The present study exemplifies a quantitative approach to floodplain food-web analysis, which can be a valuable tool for the analysis of spatiotemporal variation in trophic interactions.

This study used a creative mesocosm-approach to explore the effects of water reduction on abiotic and biotic components of streams, primarily on the macroinvertebrate community. The study was performed in two lowland streams with contrasting nutrients and used a before–after–control–impact-paired design. The negative observed effects of stagnation and drought on water quality and benthic invertebrate communities reflect the great susceptibility of lowland streams to global changes.

Fish assemblages of the Middle Paraná River floodplain were studied in the light of water variation. Several increases in water level and three flood pulses occurred during the period of study. Fish assemblage similarity was low between habitats during flood and flow pulses. Apparently, flow pulses would also function like floods, namely as mechanisms of spatio-temporal structuring of fish assemblages.

Some fish species that are protected from fishing in no-take marine protected areas (MPAs) are important in improving the health of the coral reef itself. We show that it is important to determine how the abundance of these species changes over time and at different places so that we might be able to better place MPAs and better predict how the MPAs might function.

Lycengraulis grossidens originated from freshwater lineages and is currently distributed in estuaries and coastal zones. Nevertheless, based on otolith chemistry, there are landlocked individuals in the Uruguay River. The present study investigated the spatiotemporal scenario by which these landlocked individuals reached their current distribution: whether through a north-to-south continental route based on the connection between basins or from the marine environment and showed a phylogenetic history and biogeography consistent with a north-to-south continental colonisation route.

This is the first instance of applying two independent techniques in tandem to validate age-reader interpretations of a New Zealand fish species. From zone counts on otoliths (ear-bones), black cardinalfish had been estimated to live longer than 100 years. The age-validation procedures that confirmed the longevity were lead–radium disequilibria, which uses the natural decay of radium-226 into lead-210 as a natural clock, and bomb radiocarbon (Δ¹⁴C) dating, which relies on the marine signal created by nuclear testing.

Extremely low zinc concentrations have been raising the possibility of a potential limitation for growth and distribution of marine phytoplankton. Representatives of two phytoplankton taxa (a pennate diatom and coccolithophorid) were found to adapt and grow at the extremely low zinc concentrations typical of pelagic Tasman Sea. Modification of cell physiology is suggested to be the common adaptive mechanism, although performed differently by each.

To disentangle the direct and indirect effects of ocean acidification on zooplankton growth, we undertook a study with two model organisms, Oxyrrhis marina and Acartia tonsa. Direct pH effects on consumers seem to be of lesser importance than the associated decrease in algal quality. The decrease in the quality of primary producers under high pCO₂ conditions negatively affected zooplankton growth.

Following associations are composed of nuclear species that disturb the substratum when foraging, and followers that capitalise on food resources. We compared following associations between a marine reef and a freshwater stream. Associations in the freshwater resembled three iconic reef interactions. These similarities between the systems outnumbered the differences, probably because of the shared water environment and the simple requirements for this association.

Current inadequacies in quality control throughout environmental DNA (eDNA) surveys create the potential for method error to produce false negative detections. We show how a secondary, generic primer, designed to co-amplify endogenous DNA sampled during species-specific eDNA surveys, can be used to monitor method success throughout all stages of eDNA analysis. This positive control enables the distinction of method error from informative non-amplification results, improving reliability in eDNA surveys.

We surveyed fish larvae in a semi-isolated mangrove lagoon and tested three different catch methods: minnow traps, light traps, and plankton tow nets. Overall, parrotfish and snapper were the most common larvae from coral-reef fish families, and anchovies were the most common lagoon habitat specialists. Although light traps were the most successful method, they were not as effective in turbid water.