Session B4: New Insights into Schooling Behavior in Response to Flow

Abstract: Gregarious behaviour is found throughout the animal kingdom. Although many fish species live in groups during a certain period of their life cycle, rarely has this collective behaviour been incorporated in fish passage studies, which tend to focus on individual behaviour of target species. Near fish passes, local hydrodynamics are highly variable, potentially affecting school cohesion. Since schooling has several drivers, such as antipredatory benefits and energy savings mechanisms, a loss of school integrity might be a reason fish passes act as an ecological trap for fish species that live in schools. An understanding of how hydrodynamics, encountered near fish passes, affect school cohesion and schooling behaviour is needed. A ‘back-to-basics’ study was executed that explored the response of fish schools to hydrodynamics in an experimental setting. The Common Minnow (Phoxinus phoxinus) was chosen, since it is a strong schooling species and abundant in English rivers. Minnows are quite similar in morphology and swimming movements to the important (migratory) salmonids and could therefore serve as a proxy. Movements of schools of two individuals were recorded in flowing and standing water, and their individual trajectories extracted from video data. Results show that minnows switch from a tandem configuration in standing water to a close side-by-side configuration in flowing water. Modelling work revealed that in this side-by-side configuration, energy savings could not be realised. It was concluded that fish aim to maximize information transfer when encountering flow and therefore have to rely on vision more than their lateral line system as the effectiveness of the latter is disturbed by the flow conditions. These findings suggest that passage of schooling fish is highly dependent on flow characteristics as these determine the success of collective movement and navigation through fish passes

Development and application of an agent based model for glass eel selective tidal stream transport

Temperate eel populations have been in severe decline due to anthropogenic influences. In Europe, acts of regulation are in place for the sustainable management of the European eel (A. anguilla) population, through annual assessment of commercial landings and recruitment trends. Recruitment of juvenile eels into estuaries and subsequent rivers is thought to occur through usage of the flood, ebb and slack tides (Selective Tidal Stream Transport, STST) and other environmental variables. However, instalment of estuarine barriers is known to affect upstream migration with adverse consequences for the population. To evaluate anthropogenic impact (e.g. estuarine barriers) on recruitment and aid in the improvement of population assessment, we present an Agent-Based Model (ABM) for the upstream migration of glass eels/ elvers through estuaries. A systematic review of the impacts of environmental factors based on a meta-analysis of the literature provided the behavioural parameters of the agents. The ABM is coupled to a hydrodynamic model of the Thames Estuary (UK) and simulations are validated with catchment data from different sampling sites along this waterway. Results from the meta-analysis show that the predominant mechanisms for upstream migration include drifting with the flood tide and remaining in the substratum during ebb tide, whereas exploitation of the slack tide is debatable. Water temperature, the salinity gradient, and the moon phase are the most reported environmental variables affecting STST/ migration. Based on this, the ABM proved to be successful in predicting upstream migration along the Thames while explaining the efficiency of STST. Finally, the ABM is applied The Milford Haven Waterway (UK), which is heavily exploited by human activities, to provide information on possible recruitment success here and illustrate its functionality in the context of estuarine barrier management

A review of post-whaling abundance, trends, changes in distribution and migration patterns, and supplementary feeding of Southern Hemisphere humpback whales

Southern Hemisphere humpback whales (Megaptera novaeangliae) were heavily targeted during modern commercial whaling operations, with some 216,000 individuals killed between 1903 and 1973. That impacted the abundance of all the seven breeding stocks of the species. Most of these stocks have been recovering from whaling pressure although the understanding of the current growth rates of some stocks, and how the rates compare across stocks are lacking. Updated information is fundamental for understanding the species’ current status, and to support the review of management plans promoting its protection and recovery, especially considering current changes in ocean environments due to climate change. This work offers a comprehensive overview of the current knowledge on Southern Hemisphere humpback whales breeding stocks’ status. The aim is to provide information on their post-whaling growth trends and changes in distribution and migration patterns. Within that, records of supplementary feeding records (i.e. feeding beyond their formally described feeding grounds) are described. We have also identified knowledge gaps and note that the establishment of research collaborations, as well as standard methodologies for data collection can be important steps for the acquisition of better comparable data sets for the analysis of the current status of humpback whales and to fill such gaps. The compiled information provided can be used as part of an In-Depth Assessment of the species by the International Whaling Commission.Griffith University from a private charitable trust as part of the Whales & Climate Research Program.https://www.frontiersin.org/journals/marine-science#am2024Mammal Research InstituteZoology and EntomologySDG-14:Life below wate

Do whales really increase the oceanic removal of atmospheric carbon?

DATA AVAILABILITY STATEMENT : The original contributions presented in the study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author.Whales have been titled climate savers in the media with their recovery welcomed as a potential carbon solution. However, only a few studies were performed to date providing data or model outputs to support the hypothesis. Following an outline of the primary mechanisms by which baleen whales remove carbon from the atmosphere for eventual sequestration at regional and global scales, we conclude that the amount of carbon whales are potentially sequestering might be too little to meaningfully alter the course of climate change. This is in contrast to media perpetuating whales as climate engineers. Creating false hope in the ability of charismatic species to be climate engineers may act to further delay the urgent behavioral change needed to avert catastrophic climate change impacts, which can in turn have indirect consequences for the recovery of whale populations. Nevertheless, whales are important components of marine ecosystems, and any further investigation on existing gaps in their ecology will contribute to clarifying their contribution to the ocean carbon cycle, a major driver of the world’s climate. While whales are vital to the healthy functioning of marine ecosystems, overstating their ability to prevent or counterbalance anthropogenically induced changes in global carbon budget may unintentionally redirect attention from known, well-established methods of reducing greenhouse gases. Large scale protection of marine environments including the habitats of whales will build resilience and assist with natural carbon capture.Griffith University from a private charitable trust as part of the Whales & Climate Research Program.https://www.frontiersin.org/journals/marine-science#am2024Mammal Research InstituteZoology and EntomologySDG-14:Life below wate

One-step reforming of CO₂ and CH₄ to high-value liquid chemicals and fuels at room temperature via plasma-driven catalysis

Conversion of CO₂ with CH₄ into liquid fuels and chemicals in a single-step catalytic process bypassing the production of syngas remains a challenge. In this study, one-step synthesis of liquid fuels and chemicals (e.g. acetic acid, methanol, ethanol and formaldehyde) from CO₂ and CH₄ has been achieved at room temperature (30°C) and atmospheric pressure for the first time using a novel plasma reactor with a water electrode. The total selectivity to oxygenates was ca. 50-60%, with acetic acid the major component at 40.2% selectivity, the highest value reported for acetic acid so far. Interestingly, direct plasma synthesis of acetic acid from CH₄ and CO₂ is an ideal reaction with a 100% atom economy, but it is almost impossible via thermal catalysis due to the significant thermodynamic barrier. The combination of plasma and catalyst in this process shows great potential for manipulating the distribution of different liquid chemicals

Quantification of the collective response of fish to hydrodynamics for improving downstream fish passage facilities

Migrating freshwater fish species are limited in their longitudinal movements due to barriers representing anthropogenic water resource management. Technologies, such as physical screens, designed to mitigate the effects of these obstacles on downstream migrating fish, are currently not functioning to a high standard, due to a lack of understanding of the response of fish to hydrodynamics encountered at screens. Furthermore, collective behaviour is often not considered in this context. This thesis addresses these issues through experimental studies conducted in recirculating flumes. There is a lack of understanding on the fundamental interactions that underlie collective fish movement in lotic conditions. To address this, the shoal structure and interaction rules of pairs of Eurasian minnow, Phoxinus phoxinus, were studied under flowing conditions and standing water, and energy expenditure in terms of drag modelled using CFD software. Results indicate that flow promotes shoaling but induces a change in shoal structure due to individuals aiming to maximize information transfer rather than exploiting energetic benefits. Besides economic important species, such as salmonids, the wider fish community is often ignored in fish screening research. Several experiments were carried out to assess the performance of bar racks and wedge-wire screens for downstream moving small groups of chub, Squalius cephalus, and barbel, Barbus barbus, under two discharge regimes. A horizontal alignment of bars was, for the first time, compared to the traditionally used vertical alignment in terms of hydrodynamics created at the screen and performance. Horizontal and vertical bar racks did not differ in the flow fields they induced, with mean flow primarily directed going through the racks. Avoidance responses were stronger in chub than barbel, but for both species this resulted in high numbers of entrained fish, regardless of rack configuration or discharge regime. Wedge-wire screens with a small bar spacing to eliminate entrainment seemed efficient in guiding chub, although strong avoidance behaviour was observed. Vertical wedge-wire screens induced higher sweeping velocities along the screen, however the horizontal one under low discharge produced highest guidance efficiency. The experiments confirm the importance of avoidance behaviour to hydrodynamics in the context of successfully fish screening. Shoal cohesion was weak for both species, and warrants further research into identifying the factors responsible. The results presented in this body of research are an important step to a better understanding of how fish respond to flow, which can have implications for collective modelling of animal movements in complex environments. Furthermore, it helped improve screen design criteria for the fish species used. In turn, this will help maintaining healthy fish populations that can benefit freshwater ecosystems

Dataset for: Collective behaviour of fish in the presence and absence of flow

This dataset supports the publication: de Bie, Jasper, Manes, Costantino &amp; Kemp, Paul S. (2020). Collective behaviour of fish in the presence and absence of flow. Animal Behaviour.</span

Evaluation of horizontally and vertically aligned bar racks for guiding downstream moving juvenile chub (Squalius cephalus) and barbel (Barbus barbus)

Highlights• Horizontally and vertically oriented bar racks were evaluated for fish screening • Downstream movements of groups of chub and barbel were recorded and analysed• Sweeping flows across the rack face to the bypass were not established • Consequently, total guidance was low for both species under all treatments• The bar racks used were not suitable for fish guidance under the tested conditionsAbstractBar racks are commonly installed to divert fish away from water intakes, such as those at hydropower stations or other abstraction points. In temperate regions their effectiveness has predominantly been assessed in relation to diadromous species, such as salmon and eel. This study compared the efficacy of horizontally and vertically oriented racks (5 mm diameter and 10 mm spacing) to guide downstream moving groups of five chub (Squalius cephalus) and barbel (Barbus barbus) to a bypass channel in a recirculating flume under two discharge regimes, and with the rack angled at either 30° or 45° to the direction of flow. Regardless of treatment, the bulk flow predominantly passed through the bars resulting in a lack of a well-established sweeping flow across the rack face, and consequently many instances of entrainment and impingement occurred. Total guidance (the number of bypass entries expressed as a percentage of the total number of approaches) was low and comparable between species with means of 21.3% and 24.8% for chub and barbel, respectively. Bar orientation had limited influence on all metrics, with the exception of the number of guidance events which was higher for the vertical treatment. Interspecific differences in the number of entrainments and guidance events and the exhibition of fine-scale avoidance behaviours were apparent, being higher for chub. In conclusion, the racks used here were not suitable for guiding juvenile cyprinids under conditions similar to those tested. Accounting for interspecific differences and reducing avoidance behaviour are important factors that should be considered in advancing guidance screens for multiple species. Keywords: Avoidance, Bar racks, Cyprinidae, Fish passage, Guidance <br/

Collective behaviour of fish in the presence and absence of flow

Spatial patterns in moving fish shoals originate from social interactions and are driven by factors that benefit individuals, such as predator avoidance or reduced energy expenditure. How shoaling is influenced by the presence and absence of a flow field is only partially understood. Adopting a reductionist approach, time spent shoaling, shoal structure, and information transfer between pairs (the smallest subsystem of a shoal) of Eurasian minnow (Phoxinus phoxinus) were investigated in a recirculating flume in the absence (control) and presence of flow (low and high). Minnow spent more time shoaling under high flowing conditions. The pairs tended to swim in a tandem and side-by-side configuration under static and high flowing water, respectively, while under low flow, the neighbour’s position was more uniformly distributed around the focal fish. Our approach involved analysis of fish accelerations and velocity correlations and indicated that, with the potential for hydrodynamic masking in flowing water, the relative positions adopted reflect the individual’s propensity to enhance information transfer with its neighbour by visual means so that an energy efficient configuration can be maintained. Conversely, when the energetic benefits of a side-by-side configuration are lost in the absence of flow, fish limit the costs of the partial visual impediment (on one side) imposed by the presence of a close neighbour by employing a “follow-the-leader” tactic