Marine and Freshwater Research

Ocean acidification (OA) is the ongoing change to seawater chemistry caused by oceanic uptake of increasing levels of atmospheric carbon dioxide. ‘Multiple drivers’ is the term used to describe the cumulative effects of multiple environmental factors on organisms or ecosystems. We propose that OA acts as a multiple driver, and discuss how simultaneously changing seawater properties interact to affect vulnerable marine life, including fish, shellfish, seaweeds, coralline algae, phytoplankton and corals.

Increasing concentrations of seawater carbon dioxide, called ocean acidification, could benefit some species of seaweed. Certain seaweed that can use only carbon dioxide, and not the more abundant bicarbonate, are prime candidates to benefit. We demonstrated that, in general, these species that can use only carbon dioxide respond positively to ocean acidification, although some variability exists among species’ responses.

The New Zealand Ocean Acidification Observing Network (NZOA-ON) has been developed to inform the scientific and economic challenges that New Zealand is facing in response to more acidic ocean waters. Remote field sites are distributed across New Zealand coastal waters to better understand how ocean chemistry is changing in response to increasing atmospheric carbon dioxide and how ecosystems will be affected.

The marine cycling of Cd is intriguing because it mimics the essential nutrient phosphorus (P), except at the subtropical convergence (STC). Here, we present a 3-year time series of field measurements of Cd and P concentration across the STC, New Zealand. Cadmium concentration exhibits extreme seasonality (50×), much larger than do other bio-utilised elements. The timing of the drawdown implies a biological role for Cd.

This paper focuses on taxonomy and habitat distribution of groundwater copepods in South-east Asia. We list 48 species from 22 genera documented from groundwater and groundwater-dependent habitats across the region that exhibit higher local endemicity compared to regional scale. A high number of species can still be discovered if more intensive sampling efforts and collaborative work are undertaken in the future.

The dourado Salminus brasiliensis can migrate over 200 km to reproduce in the Ivinheima River and its tributaries, indicating favourable local conditions for migration and spawning. In addition, the species exhibits differential use of biotopes for reproduction, including rivers and backwaters (spawning) and lagoons (refuge and growth). The dourado is a key species for conservation, so ensuring its reproductive success means maintaining a balanced ecological structure.

The ocean wave climate of Victoria, Australia, was analysed using 31 years of hindcast data. Wave height and period are highest on the west coast, decrease within Bass Strait, then increase eastwards to New South Wales. Wave direction is most variable on the east coast. The Southern Annular Mode and El Niño–Southern Oscillation both influence wave climate and storm frequency.

This research explored, for the first time, interactions between mantas and remoras in a marine park in the Mexican Pacific. The aim was to provide general information about the preference of the remoras for this vulnerable species of mantas, because knowledge of both species is still scarce in the area. Ecological implications regarding this interaction are discussed.

Plankton surveys of ice-covered temperate coastal lagoons are rarely conducted, probably due to logistical difficulties. In this study we surveyed plankton in the Baltic Vistula Lagoon while it was covered in ice in 2018. Environmental conditions were determined by freshwater and marine influences, and were related to the patchy distribution of both phyto- and zooplankton. There was a positive correlation between the biomass of phyto- and zooplankton.

Coral-reef ecosystems have been continuously affected by stress conditions, causing bleaching and death, allowing other competitors from the reef to use such space. We evaluated the short- and long-term changes in the cover of three reef coral genera over multi-year periods, some with abnormal temperature. Results showed that anomalies caused an ephemeral decrease in coral cover, with a remarkable presence of coralline algae. However, the communities eventually returned to their coral-dominated state, suggesting that these reef habitats are resilient to such episodes of abnormal seawater temperature.

We have studied the antibiotic pollution in fish, crab–shrimp and crab ponds around Taihu Lake Basin, China. We also evaluated a risk assessment of antibiotics with regard to organisms.

Giant trevally (Caranx ignobilis) are an iconic reef fish common to tropical and subtropical waters from South Africa to Hawaii. Despite their broad range, importance as a top predator and attraction among anglers, the growth and lifespan remain largely undescribed. In this study, giant trevally were aged up to 25 years using otolith (ear stone) growth rings and bomb radiocarbon dating.

We explored how different abiotic drivers interacted to affect recruitment in the river blackfish. We found that temperature was the primary variable that determined recruitment success, whereby highest recruitment happened in cooler streams. In addition, temperature was found to interact with riparian cover, with the highest recruitment found in cooler streams that also had high riparian cover.

This study investigated how differences in carbon and nitrogen isotopes in food sources could affect these values in shrimp. The time needed for isotope values in shrimp to stabilise after a dietary shift was determined, and correlations between isotope values in feed and shrimp were calculated. The results will help refine stable isotope traceability technology.

Determining the age of rockfish is difficult. Their otoliths (ear stones) have growth zones that are difficult to count. Hence, we used bomb-produced radiocarbon to confirm fish age independently. In redstripe rockfish there was a small probability of underageing; in harlequin rockfish there was a large probability that the fish were underaged; and in shortspine thornyhead and shortraker rockfish, the bomb-produced radiocarbon was probably not an effective tool.

The Gulf of Mexico is highly diverse in natural resources. However, some areas, especially the southern Gulf of Mexico remain understudied. Current research has provided new information for ~19 shark species at Campeche Bank, with 70% being threatened or endangered. Many species use this area for reproduction and nursery, such as the bull shark an endangered species. We found an interesting seasonal pattern in shark fishery.

The coastline of northern Australia may be a refuge for elasmobranchs threatened throughout their former ranges in South-East Asia. In this study, baited underwater videos were used to document elasmobranch communities in the Cobourg Marine Park. Overall, the abundance and diversity were high compared with other turbid environments of northern Australia. A predominance of juveniles may also indicate the presence of a nursery.

Understanding how topography and human activities affect cyanobacterial dominance and blooms can effectively protect water ecological health. Based on the dominant species in the cyanobacteria community, key driving environmental factors were identified. Further spatial classification found topography and human activities were highly correlated with the key driving factors. The results can provide references for cyanobacterial bloom prevention across the world.

A spatial knowledge-constrained manual method combined with high-resolution images was adopted for interpretation of China’s coastal wetlands. The results showed that, during the past 6 years, 12 types of coastal wetlands in China had undergone a decrease in distribution. Coastal reclamation was obvious in Bohai Bay, Yancheng tidal and Hangzhou Bay. Farming reclamation mainly occupied mudflats, shallow sea, tidal flats and estuaries waters.

Algal symbionts play a critical role in the energy budget of the coral. In this study, we demonstrate that the algal symbionts are significantly affected at temperatures below when visual coral bleaching signs are observed. It is clear that our current understanding of bleaching has overlooked what is happening to the symbiosis before bleaching is visually evident on coral reefs.

Callianassid shrimp residing in deep burrows have large effects on marine soft-sediment environment and benthic community. In light of top-down forcing in communities, substantial predation impacts on shrimp populations may cause various knock-on effects. This study revealed aspects of stingray feeding on shrimp and provided a substantial approximation to the decline of a shrimp population due to the predation impact.

Cyanobacterial ‘blue–green algal’ toxins are produced by some harmful algal blooms (HABs). To investigate the prevalence of cylindrospermopsin (CYN) and anatoxin-a (ANA) in Singapore’s reservoirs, a hazard analysis was initiated to profile the CYN and ANA levels present. The dominant cyanobacteria genera during that 12-month period (November 2012–2013) were Cylindrospermopsis, Planktolyngbya, Pseudanabaena and Microcystis.

Microcystins (MCs) are a group of toxins produced by certain cyanobacteria that occur naturally in fresh waters and can cause acute poisoning in humans and animals. A comprehensive survey was undertaken over a 12-month period in 17 reservoirs from November 2012 to October 2013 and determined that toxin levels were primarily well below the WHO provisional MC-LR drinking water guideline.

Triggerfish play an important ecological role in tropical ecosystems. By combining acoustic and video observation, we open up the field for direct biomass estimation. In addition, oceanic triggerfish assemble around fish aggregating devices used by tuna fisheries. We show that the acoustic response of triggerfish and small tuna overlap, preventing their acoustic discrimination, which may lead to high rates of bycatch.

This report is the first published, detailed description of white sharks attacking and killing a live humpback whale (Megaptera novaeangliae). New behaviours were exhibited, including those that have previously only been described in pinniped-related white shark feeding events.

Spartina alterniflora Loisel. is a coastal invasive species, and biological invasion is a global issue. In this article, previous studies investigating S. alterniflora using molecular biological techniques that have contributed to our understanding of the competitive advantage and invasion mechanism of S. alterniflora are summarised from the individual, population and application perspectives.

Our findings showed that change in land use and cover (natural vegetation to pasture) benefits some generalist species such as Phenacorhamdia somnians. Additionally, we observed that streams located in forests present the highest species richness, followed by streams in pasturelands and eucalypt matrices. We did not observe differences in the composition of fishes among the three matrices (pasture, natural vegetation and eucalypts).

This study documents early evidence of microplastics attached to several species of macrophytes (seaweeds and seagrasses) by measuring the amount of microplastic adhered to their surfaces. Microplastics can enter the food web when herbivores graze on these contaminated macrophytes.

In this study, we explore the likely sequence of events responsible for the radiation of walking sharks in the genus Hemiscyllium using a dated molecular phylogeny. The nine currently recognised species in the genus consist of small, benthic sharks with limited dispersal. Our findings support recent speciation in this genus over the last 10 million years, mediated by major tectonic, geological and oceanographic historical processes.

Soil seed banks are important components of ecological restoration, particularly if seeds of key structural dominants can survive periods of cultivation. We found that the key structural Carex was missing in farmed sedge meadows, although other important wetland species survived cultivation as seeds. This study provides important insights into biodiversity restoration of farmed sedge meadows.

We studied the relative importance of bacterial β-diversity components (turnover and nestedness) in 25 shallow lakes. Turnover was predominantly due to environmental filters, but was replaced by nestedness with increasing geographical distance between lakes due to dispersal limitation and differences in richness due to wind-driven mass effects.

The East and South China seas are important fishing grounds with very limited publicly available data. We digitised historical records of catch and effort from government fishery reports for nine commercial species caught by otter trawl, and reported quarterly from 1970 to 2001, from Taiwan to illuminate species and community changes in this region. We found substantial spatial, temporal and spatiotemporal variation in the distribution of fishes and season-specific patterns.

Half a million mangrove seedlings were planted over 30 years along an artificial causeway of dredged material in the Arabian Gulf, which was showing signs of erosion. Plantings resulted in 16.5 ha of successfully established mangroves along ~7 km of shoreline. Survival rates of ~30% increased markedly when planting sites were established in tidal channels excavated along the causeway, ensuring appropriate tidal inundation.

We assessed the structure and biological characteristics or ‘traits’ of macrofauna from 24 south-east Queensland mudflats to determine the impacts of urbanisation on ecological functioning. Overall, when indexed as a proportion of subcatchment area, no clear effect was apparent, but mudflats from subcatchments producing organic wastes differed in structure. Under current enrichment functioning was conserved; however, compensation may cease as pressures increase.

Marine fish are a major source of human and seabird exposure to methylmercury. Mercury concentrations vary according to the trophic level of commercially important marine fish from South China Sea. In this study, low biomagnification of mercury in the fish food chain is demonstrated in the South China Sea, and factors related to mercury concentrations are discussed.

A series of experiments conducted in a flow-through tank revealed that current velocity, temperature and oil thickness significant affect the refloating process of an oil patty. Furthermore, an empirical model was introduced and found to be closely consistent with the experimental data. The results can be widely used in practice.

Grapsoid assemblages were surveyed in six mangrove sites in the Malay Peninsula. Species composition differed among sites with different types of substrate and forest area. Most species appear to be stenotopic or have patchy distribution. Management actions should consider the marked variability in species composition and environmental factors, to prevent local extinctions of species and sustainably manage these ecosystems ecological diversity.

The seagrass Zostera muelleri has, in recent decades, declined massively along the eastern coastline of Australia. To restore this important marine plant, we tested multiple techniques for transplanting mature adult seagrass shoots. Results showed that transplantation works best when shoots are anchored and bioturbating animals are excluded. However, in areas where grazing fish are present, the transplanted shoots should be further protected by placement of cages above the shoots.

We explored a multilevel approach to providing a monitoring tool to detect teratogens dissolved in waters by extending the potential of tracking human-mediated detrimental environmental changes using overlapping information from short-term responses in an embryo toxicological assay based on freshwater polyps and two biotic indices based on plants and invertebrates. The findings show that the embryo toxicological assay may be considered a good early-warning system of potential teratogenic threats.

After incubating river water with carbon-13-labelled glyphosate for 6 days, we found significant shifts in bacterioplankton community composition. Bacterial richness and diversity were decreased in the 100 µg L^–1 glyphosate treatment, where 1.2% of glyphosate was converted to AMPA and a significant enrichment of carbon-13 in the bacterial biomass was detected. These results suggest that glyphosate in the water is likely more resistant to degradation than reported.

A study of biological communities associated with the last known remaining native flat oyster reefs, in north-eastern Tasmania, Australia, found that they contained greater biodiversity of fishes and invertebrates and three times the abundance compared with surrounding soft sediment sites. These diverse animal assemblages were probably lost when oyster reefs disappeared around southern Australia after European settlement.

Halophila ovalis was subjected to shading treatments for 12 weeks to investigate the effects of reduced light level on seagrass morphology, chlorophyll concentration and optimal temperatures for net productivity. Shaded seagrasses experienced reductions in shoot density and leaf size, and increases in chlorophyll concentration. The range of optimal temperatures for net productivity did not vary with light availability.

Murray crayfish (Euastacus armatus) were historically abundant in Australia’s Murray–Darling Basin, but river regulation, pollution and overfishing have reduced their range and abundance. Angler surveys quantified recreational catch, effort and harvest of crayfish in the Murrumbidgee River, which were then used to predict likely outcomes from changing harvest regulations. The model predicted that the change to a harvest-slot length limit would stabilise the population in the first 25 years and slowly increase it thereafter.

Two low-cost (less than A$10 000) commercially available towed video and remotely operated vehicles were compared for their abilities to collect photographs of marine habitats and videos of fish assemblages. Both systems performed equally well for these purposes, but towed video was simpler to operate and required significantly less time to collect data.

This study shows that current thresholds designed to protect the health of streams in South Australia need to be more stringent. We used a type of algae known as diatoms to assess whether the concentration of salt and phosphorus affected the species found in South Australian streams. The species composition changed at salinity and phosphorus concentrations well below existing thresholds.

Samples from 15 farms were used in the present study and analysed by nine microsatellite DNA loci. High heterozygosity and polymorphism information content values were obtained. The genetic differentiation was small, suggesting genetic homogeneity among hatchery-produced offspring. The most immediate and effective conservation priority should be maintaining the current genetic diversity.

Cyanobacteria are an influential and widely acknowledged biological component of lake water quality assessment. Nevertheless, there are gaps in the monitoring of cyanobacteria. In this article we review widespread problems in the use of cyanobacteria in Water Framework Directive-related water quality assessment (i.e. exclusion of taxa, mucilage carbon of the colonial species, sampling depth) and suggest solutions to optimise water quality assessment.

The witch guitarfish is caught incidentally in bottom trawl nets used in the shrimp fishery in the Gulf of Tehuantepec. Adults are probably concentrated at depths >60 m in the Gulf of Tehuantepec during most of the year and migrate towards shallow waters (from 25 to 37 m) to reproduce in February. The incidental catch of witch guitarfish during its reproductive cycle using bottom trawl nets could negatively affect the reproductive success and long-term viability of this species.

The first record of azaspiracid (AZA)-2 in plankton samples from Argentinean waters is presented herein, together with the first detection of Azadinium obesum in the southern hemisphere and four other Azadinium species, of which two are potentially toxigenic. The diversity, wide latitudinal distribution and high abundances of Azadinium plus the detection of AZA-2 found in this study highlights the potential risk of AZA shellfish contamination episodes in the south-west Atlantic Ocean.

We compared aquatic leaf breakdown between an arboreal and a grass species in two streams of the Brazilian Atlantic Forest, one draining mostly forests and the other draining mostly pasture lands. Grass breakdown was faster than that of arboreal plants in the forest stream, but not in the pasture stream. In both streams, aquatic invertebrates assimilated more forest leaves than grass leaves.

Indigo barb Pethia setnai is one of the endemic fish species present in the Western Ghats of India. This species is currently exploited from the wild for the ornamental fish trade. This study is the first report of the population dynamics of this endemic cyprinid and will help in planning future sustainable management practices.

In the past two decades, half of the once oligotrophic lakes of Montebello, Chiapas, have been affected by eutrophication, which has led to many changes in water quality and ecological interactions. We found a marked change in dominance in turbid lakes and that the relationship between turbidity and richness is unimodal, consistent with the intermediate productivity theory.

A review of trace elements and hydrocarbon contamination in Australian sea port environments revealed marked trace metal (As, Cu, Pb, Cd, Zn and Ni) contamination in the water and sediments of Port Derwent, Port Kembla, Port Botany Bay and Port Newcastle, and polychlorinated biphenyls, dichlorodiphenyltrichloroethane and chlordane contamination in the aquatic biota at Port Jackson and Port Brisbane.

We describe the structure of eight remnant Sydney rock oyster (Saccostrea glomerata) reefs and estimate the density, biomass, productivity and composition of mobile macroinvertebrate and infaunal communities associated with them. The oyster reefs had a distinct assemblage of macroinvertebrates, with fivefold higher biomass and almost fivefold higher productivity than adjacent bare sediments.

Trochus are large tropical marine snails that are collected across the Indo-Pacific region for their beautiful mother of pearl shells, but are often overharvested. This investigation used genetics to measure how often trochus larvae are transported between coastal reefs and offshore atolls in north-western Australia. Results confirm that such movement is rare, and so separate management of these regions is appropriate.

The diet composition of silver carp and bighead carp in two lakes with varying productivity was investigated by high-throughput sequencing analysis. Silver carp feed primarily on phytoplankton and exhibit feeding selectivity. Bighead carp feed primarily on zooplankton, but exhibit a dietary shift to phytoplankton with increasing levels of algae. Gaining knowledge of the feeding habits of planktivorous fish can provide insights into the management of water eutrophication problems.

This study revealed differences in the ecological role of soft-substrate tide pools between estuary and coastal tidal flats. The different types of tidal flat play different roles for groups of transient species, but similar roles for residents. Accordingly, we should consider not only species diversity, but also habitat use patterns of individual species through their life history when evaluating habitat value.

Impoundment of the Yangtze River formed the largest reservoir in the world and led to spatial and seasonal fluctuations in food availability for native fish. In less than a decade, dietary plasticity facilitated the adaptation of three generalist catfish species to the novel habitats formed by the dam. This study enhances understanding of mechanisms that allow generalist species to maintain co-occurring populations in such dramatically changing habitats.

The effects of climate on fish in the Bohai Sea and Yellow Sea were evaluated, and highly vulnerable fish species were identified. Nearly half the dominant fish species were highly vulnerable, whereas 84% of species were at high impact risk. Miichthys miiuy was found to have the highest impact risk, whereas Acropoma japonicum had the lowest. Demersal fishes tended to be more vulnerable than pelagic fishes.

Gammarus roeselii is one of the successful non-indigenous species recently established in the Ticino River basin. In this study we assessed the spatial distribution of this amphipod in the secondary hydrographic system of the southern part of the sub-lacustrine Ticino River basin and examined substrate preferences on the basis of laboratory experiments.

The survival of eastern school prawn increased significantly with increasing dissolved oxygen concentrations. Total fatty acid and amino acid concentrations were significantly greater in prawns subjected to hypoxia, regardless of aluminium exposure, with differences in fatty acid and amino acid profiles attributed to docosahexaenoic acid, stearic acid, palmitic acid and behenic acid (fatty acids) and leucine, isoleucine, phenylalanine and asparagine (amino acids).

Using satellite telemetry, this paper unravels aspects of the horizontal and vertical movements of scalloped hammerhead sharks (Sphyrna lewini) for the first time in the equatorial and south Atlantic Ocean and helps fill the gap on the species’ ecology.

We sampled fish and evaluated herbivory on the reef platform at Browse Island, 200 km off north-western Australia. We found 99 fish species, 18 of which are known to eat turf, but only 4 that eat macroalgae. Fish were eating turf on the reef, but we found no evidence they were eating macroalgae. This may make the reef more vulnerable to overgrowth of algae in the future.

Population dynamics provide crucial information for management and conservation. In this study we analysed the spatiotemporal patterns in reproductive biology, age and growth of Astyanax aff. fasciatus from a Neotropical river affected by human activities. The reproductive behaviour of the species was not homogeneous along the river due to geomorphology and human activities in surrounding areas, with some sites becoming unavailable for breeding.

Populations of the apple snail Pomacea dolioides are more affected by egg predation in rural areas of the Amazon than in urban areas. In urban areas, it is likely that human action and subsequent changes in the natural environment are favouring the reproductive success of P. dolioides by reducing egg predation. The main predators of the eggs of P. dolioides were the ants Solenopsis invicta and Crematogaster cf. carinata.

Analysis of a long-term tag–recapture dataset for Australian east-coast snapper (Chrysophrys auratus) indicated they are largely resident on a decadal time scale and at reasonably small spatial scales. However, the population exhibited ‘partial migration’, whereby a small percentage of fish moved considerable distances (up to 1000 km). Growth rates of recaptured fish were affected by latitude, with higher growth rates at lower (more northern) latitudes.

The plankton trophic structure determines how efficiently energy is transferred through aquatic food webs. We evaluated the seasonal dynamics of phytoplankton, microzooplankton and mesozooplankton in a well-mixed, highly polluted tropical estuary and, based on their interactions, proposed a conceptual trophic model for the plankton community. Rainfall is the most important environmental variable in this system and microzooplankton play a key role in its food web.

This study provides information on the bioaccumulation and potential health risks of polycyclic aromatic hydrocarbons (PAHs) in oysters and gastropods collected from the Can Gio Coastal Wetland, Vietnam. The results indicate that both oysters and gastropods contained PAHs, especially those collected from port sites, but there is no current risk to humans due to oyster and gastropod consumption.

Detailed size and sex compositions were obtained from catches of the shark longline fishery in Papua New Guinea. Silky sharks were the dominant shark caught in this fishery, constituting more than 90% of the catches. Misidentifications of species by observers was low (~10%) reflecting the use of regional identification guides and observers who are well trained.

The reproductive strategy of the small-spotted catshark was studied based on both macroscopic and microscopic observations of the reproductive tract in 2253 individuals sampled as bycatch in Hellenic waters (eastern Mediterranean Sea). The species exhibited a K-selective strategy, and information regarding its reproductive period, size at maturity, fecundity, morphometrics of oocytes and egg cases and somatic indices is presented and discussed.

Weather variables affect eutrophication indicators in estuaries. We tested the hypothesis that cool and rainy weather in midsummer has a stronger stimulatory effect on indicators of eutrophication in the Neva Estuary than warm weather. The analysis showed that total phosphorus and chlorophyll concentrations and primary production in the estuary were positively correlated with the amount of precipitation and the number of rainy days in the region.

Fish mortality through floodplain pumping stations is a recognised global issue, but few studies have quantified the impact of such infrastructure. This study aimed to use passive acoustic monitoring to record and identify the sounds generated when fish move through pumping stations. It is envisaged that this tool has application not only in quantifying eel mortality, but also as an early detection tool to illicit and test an appropriate management response.

Oxygen consumption in the aquatic environment is often assumed to be constant over time in the dark. Here we report non-constant respiration rate on the basis of analysis of a diverse dataset and describe how the patterns in respiration rate vary with the community structure and the trophic status of the ecosystems. These findings will help us better understand carbon cycling in the aquatic ecosystem.

Catch data from commercial fisheries can provide an indicator of stock status. Naïve, univariate and multivariate time series models of monthly catch per unit effort were developed for King George whiting, snapper and southern calamari. Predictive models that included seasonality or environmental variables performed the best, particularly for species that are vulnerable to fishing during short phases in their life history or for which intra-annual variation in abundance occurs through environmental variability.

Human activities alter the growth of coastal wetland vegetation. In the present study, we showed that the use of canopy hyperspectral data can reveal the biomass of Suaeda salsa under the influence of different types of human activity. This study provides technical support for the use of quantitative remote sensing-based methods to monitor the fragile ecology of coastal wetlands under the influence of human activities.

We analysed a historic database of blue marlin catch. We used a numerical model to evaluate the effects of marine climate indexes in the variations of blue marlin catch. These variations are more affected by operational changes in the longline fishery than by variations in marine climate. Blue marlin catch showed an important decrease from the early 2000s, and the causes of this decline should be investigated.

We investigated the number and distribution of trevally species in the Pseudocaranx dentex complex in Australian waters. We found one species (P. sp. ‘dentex’) that shows close affinities with trevallies from southern Africa and the Mediterranean Sea, another (P. georgianus) that is widespread in southern Australia and a third (P. dinjerra) from deep water in Western Australia. These results will facilitate the management of harvested stocks of this complex.

Alimentary exposure is the main factor determining halogenated organic compound pollution of wildlife. Comparisons of two aquatic environments, namely marine coast (Gdansk Bay) and an inland reservoir (Włocławek Dam on the Vistula River), indicated significant differences in contamination of birds’ eggs. Concentrations of polychlorinated dibenzo-p-dioxins and furans as well as polychlorinated biphenyls were similar but TEQ were several times higher in fish eating birds. The same was observed for hexabromocyclododecane isomers

Large Cladocera species are considered as keystone species in many freshwater ecosystems. Fish predation usually reduces their populations, with a cascading effect on phytoplankton biomass. A mesocosm experiment suggested that an intentional elimination of Daphnia females with more visible advanced embryos can strengthen the top-down effect of fish predation on reproduction success of daphnids and, therefore, decelerate their population growth.

Remote sensing constitutes a tool to complement field monitoring of massive growths of cyanobacteria (blooms). In a South American reservoir with recurrent blooms, we obtained 75 hyperspectral signatures in the field under conditions of cyanobacteria dominance. We used the field signatures to simulate signatures in seven satellites, and developed mathematical formulas (algorithms) for each satellite to estimate the number of cyanobacterial cells in the field.

Managing a fish population often requires understanding its diet, which involves many hours spent using a microscope to examine the contents of the fish guts. We used a DNA-technique that rapidly identified the prey of two species of blackfish that can cohabit zones of rivers. We showed that some prey were consumed by both species, but other prey were only present in one of the species. Different diets can allow two species to coexist.

Cyanobacteria can undergo rapid proliferation and lead to hazardous environmental conditions, including the production of toxins. Anatoxin-a and its analogues are cyanobacterial neurotoxins that have been found globally. This study examined their occurrence in various surface waterbody types and organisms around the world and associated aquatic toxicity, and identified research needs for understanding exposure conditions and risks for wildlife and humans.

Food availability, competition, predation and salinity affect the survival and growth of aquatic invertebrates, such as rotifers. Brachionus plicatilis (saline) and Brachionus calyciflorus (freshwater) coexist in Salado River basin waterbodies (Argentina) depending on particular conditions. The findings of this study indicate that B. calyciflorus is more adversely affected than B. plicatilis by competition and high salinity, which explains how both species can coexist.

In this study we assessed how often flatback turtles returned to nest and the environmental cues they use to time their nesting attempts. Turtles nested every 13 days within a season and returned to nest every 2 years on average within ~450 m of their previous nesting location. Turtles preferred to nest on the least exposed side of the island and when air temperature and humidity were lowest and tides were highest.

Studies on keystone species will contribute to the understanding of community stability and mechanisms underlying ecosystem degradation. Leptochela gracilis, Loligo sp., Larimichthys polyactis, Alpheus japonicus and Oratosquilla oratoria were identified as keystone species in the Haizhou Bay food web, and their absence may have considerable effects on the complexity and stability of the Haizhou Bay food web. This study provides a scientific basis for the protection of maintenance of ecosystem health in Haizhou Bay.

The coupling of a dynamic energy budget (DEB) model with an integral projection model (IPM) is a promising new method to predict the population-level dynamics of species based on individuals. We present a DEB-IPM to describe the dynamics of a population of individuals. The predicted demographic rates were well within observed ranges, and fit within average recorded values, and captured known seasonal trends.

This study used a sampling strategy designed to examine the relationship between the seasonality of a tropical river and community structure, using data from Amazonian benthic fish assemblages. It was found that species composition varies seasonally, and these differences may suggest a narrow relationship between the benthic ichthyofauna inhabiting the main channel and the marginal wetlands.

Lay summary. To gather information on oceanic life histories and possible differences in spawning times and locations of freshwater eels in the western South Pacific, otoliths of three species occurring in Fiji were studied. Significant differences between the life histories of all three species were observed. Furthermore, separate peak seasonal spawning periods for each of the three species was revealed.

Cyanobacteria can cause water quality problems through excessive biomass and the production of toxins. Their ability to become abundant is aided by specialised cells (heterocysts) that obtain nitrogen from the atmosphere. A simulation model describes the dynamics of these specialised cells, of biomass and of the nutrients nitrogen and phosphorus. This model can be used to aid predictions of cyanobacterial biomass and toxins.

Little is known about the response of soil microbes to changing inundation frequency in floodplain wetlands. This issue was investigated in the Macquarie Marshes, south-east Australia. We found significant differences in response among soil microbes, including Cyanobacteria. Changing inundation frequency is likely to affect wetland soil health and microbial diversity by altering the subtle balance of microbial communities.

Food web network interactions among micro-organisms induce or inhibit blooms. This paper reviews interactions between cyanobacteria, zooplankton and other micro-organisms, because these biotic interactions are not well recognised. The paper describes new areas of research, the results of which provide us with a better understanding of the processes of proliferation, migration and invasion of cyanobacteria.

This paper describes the first attempt to use a drone and marker pigments for fast determination of phytoplankton in harmful cyanobacterial bloom studies in selected Bulgarian shallow waterbodies. Microcystins, saxitoxins and cylindrospermopsin were detected in samples with the highest cyanobacterial content. Further use of drones and marker pigments in the monitoring of harmful algal blooms is recommended.

Cyanobacterial blooms pose a serious risk to human health and the environment in urban reservoirs. Monitoring these events using traditional methods can be expensive and impractical. Using remote sensing technologies, like satellite imagery, can be an effective and inexpensive alternative. In this study we show that concentrations of chlorophyll-a, a cyanobacteria indicator, can be inferred from Sentinel-2 images.

Mitigating global expansion of harmful cyanobacterial blooms is a major challenge. In addition to reducing nutrient inputs and optimising hydrological controls, there is the challenge of addressing effects of climate change, including warming, more extensive droughts and extreme precipitation events. Currently used control approaches will need to be re-evaluated in light of the synergistic effects of climate change with nutrient enrichment.