Ecological monitoring to support Water Sharing Plan evaluation and protect wetlands of inland New South Wales,Australia

Government‐funded flow response monitoring and modelling programmes (flow science) provided by the New South Wales Office of Water (NOW) have supported water resource management since 1997. Flow science has a core technical component defined by hypothesis‐driven long‐term monitoring and analysis, but it also represents many activities that support committees involved in environmental flow management. This is done through collaborations and contracting and has fostered considerable research and analysis into flow ecology, including modelling for the recent Murray–Darling Basin Plan. We describe the performance of environmental flows against legislated wetland objectives to improve wetland function and diversity using flow science. On‐ground monitoring at wetland sites has largely ceased but the flow science done so far indicates that the environmental flow rules written into Water Sharing Plans improve wetland diversity and function. Determination of the long‐term flow needs of NSW wetlands, including how well current Water Sharing Plans aid the delivery of environmental flows, requires finding the means to build on current flow science knowledge from across Australia.     

Effects of flooding on recruitment and abundance of Golden Perch (Macquaria ambigua ambigua) in the lower River Murray

Flooding is often considered a stimulus for production of fish in floodplain rivers. In the southern Murray–Darling Basin (MDB), Australia, however, few native fish species have been shown to use the floodplain for spawning, and recruitment has been positively and negatively associated with flooding. In 2010/11, extensive flooding in the lower River Murray provided an opportunity to investigate the recruitment response of Golden Perch (Macquaria ambigua ambigua) following 10 years of drought and floodplain isolation. Annual variation in Golden Perch abundance and recruitment were investigated in anabranch and main channel habitats at Chowilla in the floodplain geomorphic region of the lower River Murray over a 7‐year period incorporating the flood and 6 years of in‐channel flow. Spatial variation in recruitment in the lower River Murray was also investigated by comparing the age structure of Golden Perch in the swamplands/lakes, gorge and floodplain geomorphic regions. Golden Perch abundance in the Chowilla region increased significantly postflooding compared with drought years. Age structures indicated that increased abundance was due predominantly to fish spawned during the flood (2010/11) and the previous year (2009/10), which was characterised by in‐channel flows. Age structure was similar in the nearby Katarapko Anabranch system indicating a uniform postflood recruitment response in the floodplain geomorphic region. Juvenile Golden Perch from the 2010/11 and 2009/10 cohorts were less apparent in the gorge and swamplands/lakes regions. Golden Perch have flexible life histories and will spawn and recruit in association with in‐channel rises in flow and overbank flows, but significant increases in abundance in the lower River Murray may result from overbank flooding. Contemporary approaches to flow restoration in the MDB emphasise overbank flows and floodplain processes. We suggest, however, that environmental flow management that incorporates floodplain and in‐channel processes, at appropriate spatio‐temporal scales, will result in more robust populations of Golden Perch.     

The case for environmental flow determination for the Phongolo River,South Africa

The construction of Pongolapoort Dam in 1973 on the Phongolo River in KwaZulu-Natal, South Africa, has considerably altered the hydrological behaviour and ecological response of the downstream floodplain. Changes in the flooding regime have had implications for the socio-economic importance of the floodplain and for the structure and functioning of its associated wetlands. Previous studies have recommended annual releases of water from the dam to sustain floodplain ecosystem goods and services. The current artificial water releases are limited by the size of the dam's sluices and by the demand for water from the local community. Therefore, water releases do not always follow the original natural flooding regime. To date, the influence of the changed hydrology on the ecology of the Phongolo floodplain system remains poorly known. As a basis for future integrated interdisciplinary research we synthesised the ecological and hydrological work conducted to date on the Phongolo floodplain. We suggest hydro-ecology as an important research direction needed to set environmental flows for the sustainable utilisation and management of the floodplain. Understanding the hydrological behaviour and ecological response of the Phongolo floodplain could help in the implementation of environmental flows by managers at the Department of Water and Sanitation and other stakeholders such as Ezemvelo KZN Wildlife.     

Species-specific impact of introduced largemouth bass Micropterus salmoides in the Groot Marico Freshwater Ecosystem Priority Area,South Africa

Largemouth bass Micropterus salmoides are among the world's 100 worst invaders and negatively affect aquatic biodiversity in many regions worldwide. In South Africa there is a paucity of empirical studies describing their impacts. The impact of M. salmoides on the fish community in the Groot Marico River catchment, an otherwise near-pristine river ecosystem and a freshwater ecosystem priority area, was assessed from surveys conducted in 2012. Fish presence and abundance were enumerated using multiple survey techniques, and their association with key habitat variables and the presence or absence of M. salmoides were assessed. A total of 14 native fish species were recorded, besides introduced M. salmoides, which occupied the majority of the mainstem and several tributaries downstream of barriers to upstream movement. Canonical correspondence analysis showed that only one native species, the Marico barb Barbus motebensis, had a negative spatial association with M. salmoides. Assessment of relative distributions showed this species to be excluded from M. salmoides-invaded river reaches, whereas the other native species were not visibly affected by the invader. This species-specificity of the impact of M. salmoides indicates that their impacts in South African streams may be dependent on predator-naiveté of prey.     

Ontogenetic structure and distribution patterns of ichthyoplankton in the confluence zone of two river systems in the Eastern Amazon

The ontogenetic structure and longitudinal variability of ichthyoplankton in a confluence zone of two river systems in the Eastern Amazon were evaluated between December 2018 and April 2019, at the time 137 eggs and 7,687 larvae of fish were captured. Ichthyoplankton proved to be heterogeneous between sections of rivers with differences in the number of taxa and abundance. The assemblages were distinguished by a NMDS Analysis, a ANOSIM, a SIMPER and a CCA, they presented a spatial zonation pattern with strong distinction and variability in the composition of the species between the river systems, under strong influence of limnological variables. The assemblages were mainly represented by larvae of Clupeiformes and Perciformes in the clear waters of the Tapajós river and Characiformes and Siluriforms in the cloudy waters of the Amazon river, influenced by the existence of a limnological gradient. Larvae in more advanced development stages were predominant in the Tapajós river while early stages were dominant in the Amazon river. The confluence zone does not seem to be a spawning area, but it is an important transport site for the larvae to reach the nursery areas in the lower stretch of the Amazon river. The encounter of these two river systems seems to guarantee the survival and biological recruitment of several fish species.     

The prevalence and antimicrobial resistance phenotypes of Salmonella,Escherichia coli and Enterococcus sp. in surface water

Surface water is prone to bacterial contamination as it receives wastes and pollutants from human and animal sources, and contaminated water may expose local populations to health risks. This review provides a brief overview on the prevalence and antimicrobial resistance (AR) phenotypes of Salmonella, Escherichia coli and Enterococcus, found in natural freshwaters. These bacteria are frequently detected in surface waters, sometimes as etiological agents of waterborne infections, and AR strains are not uncommonly identified in both developed and developing countries. Data relating to Salmonella, E. coli and Enterococcus present in environmental water are lacking, and in order to understand their development and dissemination using the One Health approach, understanding the prevalence, distribution and characteristics of the bacteria present in surface water as well as their potential sources is important. Furthermore, AR bacteria in natural watersheds are not well investigated and their impacts on human health and food safety are not well understood. As surface water is a receptacle for AR bacteria from human and animal sources and a vehicle for their dissemination, this is a crucial data gap in understanding AR and minimizing its spread. For this review, Salmonella, E. coli and Enterococcus were chosen to evaluate the presence of primary pathogens and opportunistic pathogens as well as to monitor AR trends in the environmental water. Studies around the world have demonstrated the widespread distribution of pathogenic and AR bacteria in surface waters of both developing and developed countries, confirming the importance of environmental waters as a reservoir for these bacteria and the need for more attention on the environmental bacteria for emerging AR.     

Evidence of a landlocked reproducing population of the marine pejerrey Odontesthes argentinensis (Actinopterygii; Atherinopsidae)

In South America, the order Atheriniformes includes the monophyletic genus Odontesthes with 20 species that inhabit freshwater, estuarine and coastal environments. Pejerrey Odontesthes argentinensis is widely distributed in coastal and estuarine areas of the Atlantic Ocean and is known to foray into estuaries of river systems, particularly in conditions of elevated salinity. However, to our knowledge, a landlocked self-sustaining population has never been recorded. In this study, we examined the pejerrey population of Salada de Pedro Luro Lake (south-east of Buenos Aires Province, Argentina) to clarify its taxonomic identity. An integrative taxonomic analysis based on traditional meristic, landmark-based morphometrics and genetic techniques suggests that the Salada de Pedro Luro pejerrey population represents a novel case of physiological and morphological adaptation of a marine pejerrey species to a landlocked environment and emphasises the environmental plasticity of this group of fishes.     

Characterization of Dinophysis spp. (Dinophyceae,Dinophysiales) from the mid-Atlantic region of the United States1

Due to the increasing prevalence of Dinophysis spp. and their toxins on every US coast in recent years, the need to identify and monitor for problematic Dinophysis populations has become apparent. Here, we present morphological analyses, using light and scanning electron microscopy, and rDNA sequence analysis, using a ~2-kb sequence of ribosomal ITS1, 5.8S, ITS2, and LSU DNA, of Dinophysis collected in mid-Atlantic estuarine and coastal waters from Virginia to New Jersey to better characterize local populations. In addition, we analyzed for diarrhetic shellfish poisoning (DSP) toxins in water and shellfish samples collected during blooms using liquid-chromatography tandem mass spectrometry and an in vitro protein phosphatase inhibition assay and compared this data to a toxin profile generated from a mid-Atlantic Dinophysis culture. Three distinct morphospecies were documented in mid-Atlantic surface waters: D. acuminata, D. norvegica, and a “small Dinophysis sp.” that was morphologically distinct based on multivariate analysis of morphometric data but was genetically consistent with D. acuminata. While mid-Atlantic D. acuminata could not be distinguished from the other species in the D. acuminata-complex (D. ovum from the Gulf of Mexico and D. sacculus from the western Mediterranean Sea) using the molecular markers chosen, it could be distinguished based on morphometrics. Okadaic acid, dinophysistoxin 1, and pectenotoxin 2 were found in filtered water and shellfish samples during Dinophysis blooms in the mid-Atlantic region, as well as in a locally isolated D. acuminata culture. However, DSP toxins exceeded regulatory guidance concentrations only a few times during the study period and only in noncommercial shellfish samples.     

Conspecific density and environmental complexity impact behaviour of turquoise killifish (Nothobranchius furzeri)

Fish models are essential for research in many biological and medical disciplines. With a typical lifespan of only 6 months, the Turquoise killifish (Nothobranchius furzeri) was recently established as a time- and cost-efficient model to facilitate whole-life and multigenerational studies in several research fields, including behavioural ecotoxicology. Essential information on the behavioural norm and on how laboratory conditions affect behaviour, however, is deficient. In the current study, we examined the impact of the social and structural environment on a broad spectrum of behavioural endpoints in N. furzeri. While structural enrichment affected only fish boldness and exploratory behaviour, fish rearing density affected the total body length, locomotor activity, boldness, aggressiveness and feeding behaviour of N. furzeri individuals. Overall, these results contribute to compiling a behavioural baseline for N. furzeri that increases the applicability of this new model species. Furthermore, our findings will fuel the development of improved husbandry protocols to maximize the welfare of N. furzeri in a laboratory setting.