A flat-bed passive integrated transponder antenna array for monitoring behaviour of Atlantic salmon parr and other fish

A system for monitoring automatically the movements of individually identified small fish in natural habitats is described. The system incorporates novel flat-bed antennae to detect the passage of miniature passive integrated transponders.     

Development of a flatbed passive integrated transponder antenna grid for continuous monitoring of fishes in natural streams

This paper describes a flatbed antenna grid designed for continuous remote monitoring of fish tagged with 23 mm passive integrated transponder (PIT) tags in a natural stream with extensive spatial coverage. A range of applications of the system is presented.     

Over-summering behaviour of Atlantic salmon Salmo salar returning to rivers in the Cromarty Firth, north–east Scotland

In 2005, a high percentage (50%) of Atlantic salmon Salmo salar fitted with acoustic transmitters, which entered rivers in the Cromarty Firth area of north–east Scotland dropped back to the estuary and ascended adjacent rivers after 33–80 days of freshwater residence. Fish residing in non-natal rivers generate mixed stock fisheries, and movements of fish between rivers could increase the risk of disease transmission between catchments.     

A method for prioritizing the reestablishment of river continuity in Austrian rivers

River continuity is one of the hydro-morphological elements supporting the classification of the ecological status of rivers. In order to achieve good ecological status in the continuity of rivers, the impacts of anthropogenic activities must be limited to the extent that some fish age classes may be missing and there may only be slight changes in species composition and abundance from the type specific community. The main goal of the project is to list priorities for removing obstruction to migration within 12 years to reestablish river continuity so as to allow undisturbed migration of aquatic organisms. The ecological status of the river, the cost–benefit ratio of the proposed restoration and the distance between obstructions are analysed. More than 200 obstructions in about 170 km of river were evaluated. A 1st ranking of the parameter “extension of undisturbed river length” shows significant alterations in comparison with the 2nd and 3rd ranking, where the river length is weighted over the parameters “ecological status” of the river reach and the “cost–benefit ratio” of the measure. The ecological status is classified by comparing the present versus the potential natural morphological conditions (Leitbild). The cost–benefit ratio takes into account the increase of the fish species composition and the cost of the measures in relation to local circumstances of available property and height of the drop. Examples of obstructions in the Pinka R. move back in the priority list to a maximum of −9 places and forwards to a maximum of +8 places. As a result the list of obstructions by priority for removal to be removed first at the top is analysed. The financial policy and a schedule for removal for the period 2003–2015 are based upon the results of the priority list. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: R. L. Welcomme & G. Marmulla Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries     

The evaluation of passive integrated transponder (PIT) tags and visible implant elastomer (VIE) marks as new marking techniques for the bullhead

To test the reliability of PIT tags and VIE marks as new marking techniques for the bullhead Cottus gobio , different tagging treatments were assayed. The relatively high recapture rates suggest the applicability of both marking techniques for this small benthic fish species.     

城市河流的景观生态学研究:概念框架

城市河流作为城市景观中一种重要的生态廊道,其功能的正常实现与否关系到整个城市的可持续发展。通过分析当前城市河流的研究概况,发现应用景观生态学原理对城市河流展开多尺度、多学科的综合研究是实现“自然-人类-水体”可持续发展的必然趋势。从景观生态学的角度出发,结合城市河流的特点,提出了更为综合的、景观水平上的城市河流研究的概念框架。特别针对景观生态学研究的核心问题,对城市河流的研究尺度、格局分析、干扰程度等重要方面进行了详细论述,以期在景观水平上构建城市河流的可持续发展预案。     

Long‐term effects of passive integrated transponder tagging (PIT tags) on the growth of the yellow European eel (Anguilla anguilla (Linnaeus, 1758))

Passive Integrated Transponder tags (PIT tags) are recommended as the most suitable method for tagging fish on the basis of their high retention and fish survival rates. The objective of this study was to determine the long‐term effects (between 1 and 11 years) of the PIT tag on the growth of the yellow European eel (Anguilla anguilla). A difference of more than 50% was observed in the growth of marked and unmarked yellow eels. If this is a general long‐term effect in all eels, it would seriously restrict the use of PIT tags for studying the dynamics of European eel populations, and so for their management.     

Development, maintenance and role of riparian vegetation in the river landscape

1. Riparian structure and function were considered from a longitudinal perspective in order to identify multiscale couplings with adjacent ecosystems and to identify research needs. 2. We characterized functional zones (with respect to vegetation development in association with various biogeochemical processes) within geomorphological settings using a delineation based upon erosional, transitional and depositional properties. 3. Vegetation dynamics within the riparian corridor are clearly influenced substantially by hydrological disturbance regimes. In turn, we suggest that vegetation productivity and diversity may widely influence riverine biogeochemical processes, especially as related to the consequences of changing redox conditions occurring from upstream to downstream. 4. However, surface and groundwater linkages are the predominant controls of landscape connectivity within riparian systems. 5. The importance of riparian zones as sources and sinks of matter and energy was examined in context of structural and functional attributes, such as sequestering or cycling of nutrients in sediments, retention of water in vegetation, and retention, diffusion or dispersal of biota. 6. The consequences of interactions between different communities (e.g. animals and plants, micro-organisms and plants) on biogeochemical processes are notably in need of research, especially with respect to control of landscape features. Multiscale approaches, coupling regional and local factors in all three spatial dimensions, are needed in order to understand more synthetically and to model biogeochemical and community processes within the river-riparian-upland landscape of catchments.     

No effect of passive integrated transponder tagging method on survival or body condition in a northern population of Black‐capped Chickadees (Poecile atricapillus)

Passive integrated transponder (PIT) tags allow a range of individual‐level data to be collected passively and have become a commonly used technology in many avian studies. Although the potential adverse effects of PIT tags have been evaluated in several species, explicit investigations of their impacts on small (<12 g) birds are limited. This is important, because it is reasonable to expect that smaller birds could be impacted more strongly by application of PIT tags. In this study, we individually marked Black‐capped Chickadees (Poecile atricapillus), a small (circa 10 g) passerine, at the University of Alberta Botanic Garden to evaluate potential lethal and sublethal effects of two PIT tagging methods: attachment to leg bands or subcutaneous implantation. We used a Cox proportional hazards model to compare the apparent survival of chickadees with leg band (N = 79) and implanted PIT tags (N = 77) compared with control birds that received no PIT tags (N = 76) over the subsequent 2 years based on mist net recaptures. We used radio‐frequency identification (RFID) redetections of leg band PIT tags to evaluate sex‐specific survival and increase the accuracy of our survival estimates. We also used a generalized linear regression model to compare the body condition of birds recaptured after overwintering with leg band PIT tags, implanted PIT tags, or neither. Our analysis found no evidence for adverse effects of either PIT tagging method on survival or body condition. While we recommend carefully monitoring study animals and evaluating the efficacy of different PIT tagging methods, we have shown that both leg band and subcutaneously implanted PIT tags ethical means of obtaining individualized information in a small passerine.     

Ecological research for the restoration and management of rivers and reservoirs in Japan

In Japan the River Law was amended in 1997 to expand the traditional roles of flood control and water supply in river management to include environmental conservation. Two major multidisciplinary research groups were also founded to address the environmental issues arising from the management of rivers and watershed areas in Japan. One called the River Ecology Research Group was formed in 1995 to search for an ideal dynamic state of rivers to be managed. Six case studies commenced involving measurements of natural and human impacts on representative rivers and their biota selected from different regions of the country. Restoration of natural rivers has also been attempted. The other, called the Watershed Ecology Research Group, was formed in 1998 to study the natural environment surrounding dams. It consists of four groups concerned with forest ecology in the headwaters, raptor management research, reservoir ecology, and flow regime research. The topics include modeling of regeneration dynamics of riparian forests, GIS mapping of endangered raptor habitats, developing measures to reduce eutrophication of reservoir water, and the use of biodiversity of benthic faunas as an indicator of environmental change in the downstream. In both groups, ecologists collaborate with engineers who are responsible for the river infrastructure, to predict future impacts and keep ecological perspectives for the maintenance of the healthy environment of rivers and reservoirs.     

Female‐biased migration of stream‐dwelling Dolly Varden in the Shiisorapuchi River, Hokkaido, Japan

The first evidence for female‐biased migration in a partially migratory stream‐dwelling salmonid the Dolly Varden Salvelinus malma , a phenomenon well known in sea‐run and lake‐run populations, is presented. Dolly Varden in the Shiisorapuchi River in central Hokkaido, Japan, used both tributaries, of which there are many, and the main stem, but spawned only in tributaries. The size structures of Dolly Varden (≥age 1 + years) in tributaries were unimodal (<100 mm fork length, L _F) during non‐spawning seasons but changed to bimodal during spawning seasons (lower mode <110 mm, upper mode >120 mm L _F). Mature individuals were observed in both modal groups. From the trapping and census data, the small group appeared to be tributary resident and the large group main stem migrant. Males were common in both resident and migrant components. Most females, however, migrated to the main stem to mature, indicating female‐biased migration.     

The use of passive integrated transponder systems (PIT) triggered by infrared-gates for behavioural studies in nocturnal, bottom-dwelling fish species

The movements of juvenile burbot Lota lota were monitored continuously with an overall efficiency of 92·5%. The results show that passive integrated transponder (PIT) systems (or variations of them) are highly valuable for behavioural studies of small nocturnal fish species at the laboratory or mesocosm scale.     

Genetic evidence for lacustrine spawning of the non‐anadromous Atlantic salmon population of Little Gull Lake, Newfoundland

Allozyme markers were used to investigate the spatial boundaries of the non‐anadromous Atlantic salmon population of Little Gull Lake, Eastern Canada. Mixed year class samples of juvenile salmon were analysed from inlet streams, upstream lakes, the outlet river and sites downstream. No evidence was found that individuals from the Lake's non‐anadromous population were present in these samples, strongly suggesting that the non‐anadromous population is confined to the lake and has a lacustrine spawning habit.     

Studies on fish movement dynamics in a tropical floodplain river: Prerequisites for a procedure to monitor the impacts of mining

Abstract Towards the end of the Wet season in the tropical coastlands of northern Australia, there are dramatic upstream movements of many fish species in some seasonally flowing streams. These movements are considered to be a part of refuge-seeking migrations. Aspects of the dynamics of the movements in Magela Creek (in the ‘Top End’ of the Northern Territory) downstream from the Ranger Uranium Mine have been examined with a range of techniques (mainly direct observation) to facilitate the development of a possible procedure for monitoring impacts of the mine on the fish community of the creek system. Data on diel patterns of movements validated that monitoring, for 1 h at midday at a single point adjacent to the mine, reflects day-to-day changes in total diel movements. To help identify the location of any impacts arising in the future, information on upstream progress rates, longitudinal changes in movements, and movements between the creek and lowland billabongs, were used to (i) demonstrate the creek-long continuity of movements and (ii) indicate the possible sources and destinations of fish approaching the mine. Marked differences in sources were apparent for two groups of species: terapontids originating from the lowland creek channels, and chequered rainbowfish and ambassids originating from the floodplain and lowland billabongs. Identification of the relative contributions from these habitats will require additional monitoring effort.     

A review of Morphological and Behavioural Changes in the Cave Molly, Poecilia Mexicana, from Tabasco, Mexico

The poeciliid fish Poecilia mexicana successfully colonised a sulfur cave in Tabasco, Mexico. The eye size, melanin pigmentation and scale tuberances as well as aggressive and schooling behaviour are reduced in the cave fish. Besides these regressive characters some constructive ones have been found. The genital region of the female is enlarged to a genital pad and in both sexes the number of taste buds is considerably increased on the upper side of the head. The cephalic lateral line shows a hyperdevelopment with an incomplete covering of some channels. Nearly all of these characters studied form a genetically based gradient from the beginning to the end of the cave, which seems to be the result of gene flow from the outside to the inner part of the cave. A special behavioural adaptation was found among females which prefer bigger males during courtship. In darkness, only the cave females show this preference.     

A model for rapid growth evaluation in fishes: the case of the Cyprinids of some large French rivers

Starting from previous work on tropical african fishes (de Merona et al., 1983), we calculate a relationship between Loo and k and between L_OO and the maximum observed length in cyprinid populations of some French great rivers and associated man-made lakes (basins of Garonne and Rhone). 45 populations are used, and they seem to conform to the model well. The growth of both groups of populations differs only by the value of some constants. This follows from differences in the individual growth pattern of fishes, climate, and from differences in food and feeding habits.     

Plant invasions in the rivers of the Iberian Peninsula,south-western Europe: A review

Aquatic and riparian ecosystems are known to be highly vulnerable to invasive alien species (IAS), especially when subjected to human-induced disturbances. In the last three decades, we have witnessed a growing increase in plant invasions in Portugal and Spain (Iberian Peninsula, south-western Europe), with very detrimental economic, social and ecological effects. Some of these species, such as the giant reed (Arundo donax L.) and the water hyacinth (Eichhornia crassipes (Mart.) Solms-Laub.), number among the world's worst weeds. We present an appraisal of this invasive alien river flora and the most problematic aquatic weeds. We review various aspects of invasion ecology, including spatial and temporal patterns of invasion, species invasiveness, species traits of invasive weeds, and relationships between human disturbance in rivers and surrounding areas and invasibility, and contextualize them in overall state-of-the-art terms. We also acknowledge the use of IAS as bioindicators of the ecological quality of rivers, wetlands and riparian zones. Remote-sensing tools and Geographic Information Systems for detecting and monitoring IAS in Iberian rivers are presented.     

A field test of the use of pop‐off data storage tags in freshwater fishes

In the present study, pop‐off data storage tags (pDST) without any transmitting capabilities were attached to 118 adult salmonids in a 19 000 km² freshwater system (Lake Ontario). The 9·3 cm long cylindrical tags were externally attached to fishes using a backpack‐style harness, set to record pressure (dBar ≈ depth in m) and temperature every 70 s (and at some key times, every 5 s) and programmed to release from the harness and float to the surface after c. 1 year. Recapture of the bright‐orange tags for data retrieval relied on members of the public finding tags on shore, or on anglers capturing fishes with tags attached and using the contact information displayed on each tag to mail tags to the research team in exchange for a monetary reward. Thirty‐seven tags were found and returned from the 118 released (31%), while 26 of the 118 tags (22%) remained scheduled to pop‐off in summer 2017. Of the 37 tags returned, 23 were from wild‐caught fishes (out of 88 wild‐caught and tagged fishes; 26%) and yielded useful data whereas 14 were from hatchery‐reared fishes that were opportunistically tagged and appear to have been unable to acclimate to life in the wild and died days to weeks after release. The field study described here thus demonstrated that pDSTs can be a viable option for collecting large amounts of high‐resolution depth and temperature data for salmonids in freshwater systems. Technical challenges, limitations and unknowns related to the use of pDSTs with freshwater fishes are discussed. In addition, pDSTs are compared with alternate electronic tagging technologies and assessed for their potential as a more widespread tool in research on freshwater fishes.     

Targeted and passive environmental DNA approaches outperform established methods for detection of quagga mussels,Dreissena rostriformis bugensis in flowing water

1. The early detection of invasive non‐native species (INNS) is important for informing management actions. Established monitoring methods require the collection or observation of specimens, which is unlikely at the beginning of an invasion when densities are likely to be low. Environmental DNA (eDNA) analysis is a highly promising technique for the detection of INNS—particularly during the early stages of an invasion.
2. Here, we compared the use of traditional kick‐net sampling with two eDNA approaches (targeted detection using both conventional and quantitative PCR and passive detection via metabarcoding with conserved primers) for detection of quagga mussel, Dreissena rostriformis bugensis, a high priority INNS, along a density gradient on the River Wraysbury, UK.
3. All three molecular tools outperformed traditional sampling in terms of detection. Conventional PCR and qPCR both had 100% detection rate in all samples and outperformed metabarcoding when the target species was at low densities. Additionally, quagga mussel DNA copy number (qPCR) and relative read count (metabarcoding) were significantly influenced by both mussel density and distance from source population, with distance being the most significant predictor.
4. Synthesis and application. All three molecular approaches were more sensitive than traditional kick‐net sampling for the detection of the quagga mussel in flowing water, and both qPCR and metabarcoding enabled estimates of relative abundance. Targeted approaches were more sensitive than metabarcoding, but metabarcoding has the advantage of providing information on the wider community and consequently the impacts of INNS.

     

Feeding Ecology and Energetic Relationships with Habitat of Blue Catfish, Ictalurus furcatus, and Flathead Catfish, Pylodictis olivaris, in the Lower Mississippi River, U.S.A.

We examined feeding of blue catfish, Ictalurus furcatus, and flathead catfish, Pylodictis olivaris, collected from floodplain lake, secondary (side) river channel, and main river channel habitats in the lower Mississippi River (LMR), U.S.A. We described the feeding ecology of two large river catfish species within the context of whether off-channel habitats in the LMR (i.e., floodplain lakes and secondary channels) potentially provided energetic benefits to these fishes as purported in contemporary theory on the ecology of large rivers. We used diet composition and associated caloric densities of prey consumed as indicators of energetic benefit to catfishes. Differences in diet among habitats were strong for blue catfish, but weak for flathead catfish; consumed foods generally differed among habitats in caloric (energy) content. Caloric densities of consumed foods were generally greatest in floodplain lakes, least in the main river channel, and intermediate in secondary river channels. Strong between-year variation in diet was observed, but only for blue catfish. Blue catfish fed disproportionately on lower-energy zebra mussels in the main river channel during 1997, and higher-energy chironomids and oligochaetes in floodplain lakes during 1998. Results suggested that although off-channel habitats potentially provided greater energetic return to catfishes in terms of foods consumed, patterns of feeding and subsequent energy intake may vary annually. Energetic benefits associated with off-channel habitats as purported under contemporary theory (e.g., the ‘flood-pulse concept’) may not be accrued by catfishes every year in the LMR.