An integrated food web model to test the impact of fisheries management scenarios on the coastal ecosystem of Vietnam

Climate change affects ecological communities through its impact on the physiological performance of individuals. However, the population dynamic of species well inside their thermal niche is also determined by competitors, prey and predators, in addition to being influenced by temperature changes. We use a trait-based food-web model to examine how the interplay between the direct physiological effects from temperature and the indirect effects due to changing interactions between populations shapes the ecological consequences of climate change for populations and for entire communities. Our simulations illustrate how isolated communities deteriorate as populations go extinct when the environment moves outside the species' thermal niches. High-trophic-level species are most vulnerable, while the ecosystem function of lower trophic levels is less impacted. Open communities can compensate for the loss of ecosystem function by invasions of new species. Individual populations show complex responses largely uncorrelated with the direct impact of temperature change on physiology. Such complex responses are particularly evident during extinction and invasion events of other species, where climatically well-adapted species may be brought to extinction by the changed food-web topology. Our results highlight that the impact of climate change on specific populations is largely unpredictable, and apparently well-adapted species may be severely impacted.

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Current and potential contributions of the Gulf of Lion Fisheries Restricted Area to fisheries sustainability in the NW Mediterranean Sea

10.1101/2020.02.22.960914 ◽

2020 ◽

Author(s):

Daniel Vilas ◽

Marta Coll ◽

Xavier Corrales ◽

Jeroen Steenbeek ◽

Chiara Piroddi ◽

...

Keyword(s):

Food Web ◽

Management Scenarios ◽

Management Options ◽

Ecosystem Recovery ◽

Restricted Area ◽

Trade Offs ◽

Gulf Of Lion ◽

Before And After ◽

Nw Mediterranean ◽

Food Web Model

AbstractMany commercial species of the world are overexploited resulting in substantial reductions of biomass and ecological changes. Spatial-temporal restrictions of fishing activities are important measures used for the management of marine stocks. However, evidence of whether fishing bans benefit whole ecosystems is still scant. Here, we developed a food-web model approach using the Ecopath with Ecosim (EwE) model representing the Fisheries Restricted Area (FRA) of the Gulf of Lion ecosystem (CoSEGoL model) prior to the establishment of the fisheries restrictions (2006-2008) to characterize the structure and functioning of the ecosystem before and after its establishment. The constructed food-web model was, then, fitted to available time series of data from 2008 to 2016 to verify whether this FRA has contributed to recovery of target demersal species and the demersal community. The fitted model was used to explore alternative future management scenarios to explore feasible management options in order to ensure a full ecosystem recovery under climate change conditions. Both small positive and negative ecosystem changes occurred between prior and after the establishment of the FRA, potentially revealing a lack of protection efficiency and/or enforcement. Scenarios of management options under plausible climate futures revealed possible recovery of targeted species, especially European hake. The study highlighted the importance of considering trophic interactions between predators and prey to identify trade-offs and synergies in fisheries management outcomes and the need to consider both fishing and climate dynamics.

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Food web model to assess the fishing impacts and ecological role of elasmobranchs in a coastal ecosystem of Southern Brazil

Environmental Biology of Fishes ◽

10.1007/s10641-021-01120-9 ◽

2021 ◽

Author(s):

Aurora Rupp ◽

Hugo Bornatowski

Keyword(s):

Food Web ◽

Coastal Ecosystem ◽

Southern Brazil ◽

Ecological Role ◽

Fishing Impacts ◽

Food Web Model

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Assessment of Spatiotemporal Peak Shift of Intra-Urban Transportation Taking a Case in Bangkok, Thailand

Sustainability ◽

10.3390/su13126777 ◽

2021 ◽

Vol 13 (12) ◽

pp. 6777

Author(s):

Masanobu Kii ◽

Yuki Goda ◽

Varameth Vichiensan ◽

Hiroyuki Miyazaki ◽

Rolf Moeckel

Keyword(s):

Developing Countries ◽

Travel Time ◽

Demand Management ◽

Likelihood Estimation ◽

Road Transport ◽

Peak Shift ◽

Time Shift ◽

Peak Time ◽

Management Scenarios ◽

The Impact

Reducing congestion has been one of the critical targets of transportation policies, particularly in cities in developing countries suffering severe and chronic traffic congestions. Several traditional measures have been in place but seem not very successful. This paper applies the agent-based transportation model MATSim for a transportation analysis in Bangkok to assess the impact of spatiotemporal transportation demand management measures. We collect required data for the simulation from various data sources and apply maximum likelihood estimation with the limited data available. We investigate two demand management scenarios, peak time shift, and decentralization. As a result, we found that these spatiotemporal peak shift measures are effective for road transport to alleviate congestion and reduce travel time. However, the effect of those measures on public transport is not uniform but depends on the users’ circumstances. On average, the simulated results indicate that those measures increase the average travel time and distance. These results suggest that demand management policies require considerations of more detailed conditions to improve usability. The study also confirms that microsimulation can be a tool for transport demand management assessment in developing countries.

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Enhanced Viral Activity in the Surface Microlayer of the Arctic and Antarctic Oceans

Microorganisms ◽

10.3390/microorganisms9020317 ◽

2021 ◽

Vol 9 (2) ◽

pp. 317

Author(s):

Dolors Vaqué ◽

Julia A. Boras ◽

Jesús Maria Arrieta ◽

Susana Agustí ◽

Carlos M. Duarte ◽

...

Keyword(s):

Environmental Factors ◽

Food Web ◽

Physicochemical Characteristics ◽

The Arctic ◽

Microbial Food Web ◽

Surface Microlayer ◽

Polar Regions ◽

Nutrient Inputs ◽

Viral Activity ◽

The Impact

The ocean surface microlayer (SML), with physicochemical characteristics different from those of subsurface waters (SSW), results in dense and active viral and microbial communities that may favor virus–host interactions. Conversely, wind speed and/or UV radiation could adversely affect virus infection. Furthermore, in polar regions, organic and inorganic nutrient inputs from melting ice may increase microbial activity in the SML. Since the role of viruses in the microbial food web of the SML is poorly understood in polar oceans, we aimed to study the impact of viruses on prokaryotic communities in the SML and in the SSW in Arctic and Antarctic waters. We hypothesized that a higher viral activity in the SML than in the SSW in both polar systems would be observed. We measured viral and prokaryote abundances, virus-mediated mortality on prokaryotes, heterotrophic and phototrophic nanoflagellate abundance, and environmental factors. In both polar zones, we found small differences in environmental factors between the SML and the SSW. In contrast, despite the adverse effect of wind, viral and prokaryote abundances and virus-mediated mortality on prokaryotes were higher in the SML than in the SSW. As a consequence, the higher carbon flux released by lysed cells in the SML than in the SSW would increase the pool of dissolved organic carbon (DOC) and be rapidly used by other prokaryotes to grow (the viral shunt). Thus, our results suggest that viral activity greatly contributes to the functioning of the microbial food web in the SML, which could influence the biogeochemical cycles of the water column.

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Assessing the Impact of Management Options on Water Allocation in River Mubuku-Sebwe Sub-Catchments of Lake Edward-George Basin, Western Uganda

Water ◽

10.3390/w13152009 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2009

Author(s):

Caroline Ednah Mwebaze ◽

Jackson-Gilbert Mwanjalolo Majaliwa ◽

Joshua Wanyama ◽

Geoffrey Gabiri

Keyword(s):

Water Use ◽

Water Demand ◽

Water Allocation ◽

Management Scenarios ◽

Management Options ◽

Available Water ◽

Lake Edward ◽

Western Uganda ◽

The Impact ◽

Sustainable Water Resources

Limited studies in East Africa and particularly in Uganda have been carried out to determine and map water use and demands. This study aimed at assessing the impact of management options on sustainable water allocation in environmentally sensitive catchments of Mubuku and Sebwe of Lake Edward-George basin in Western Uganda. We used hydro-meteorological data analysis techniques to quantify the available water. We applied Mike Hydro model to allocate water to the different ongoing developments in the catchment based on 2015 and 2040 water demand management scenarios. We used the Nile Basin Decision Support System to assess the sustainability of the different water management scenarios for sustainable water resources use. Reliability computation did not consider hydropower in this study. Results show that water available in 2015 was 60 MCM/YR and 365 MCM/YR for Sebwe and Mubuku, respectively and is projected to decrease by 15% and 11% by the year 2040 under climate scenario RCP8.5. We project water demand to rise by 64% for domestic, 44% for livestock, 400% for industry, 45% for hydro power and 66% for irrigation by 2040. Mubuku water demand is projected to increase from 5.2 MCM in 2015 to 10.7 MCM in 2040. Mubuku available water is projected to fall from 364.8 to 329.8 MCM per annum. Sebwe water demand is projected to increase from 9.7 MCM in 2015 to 22.2 MCM in 2040 and its available water is projected to fall from 60 to 52 MCM per annum by the year 2040 from 2015. Water managers ought to allocate water based on the reliable water allocation which prioritizes domestic and environmental water demands, allocates 90% of industrial demand, 70% of irrigation and 60% of livestock demand. We recommend institutionalizing this model to guide water allocation in the Mubuku-Sebwe sub catchments. Water users should employ more efficient water use techniques to achieve high reliability and sustainable water resources management.

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INCORPORATING TEMPERATURE-DEPENDENT FISH BIOENERGETICS INTO A NARRAGANSETT BAY FOOD WEB MODEL

10.23860/thesis-heinichen-margaret-2021 ◽

2021 ◽

Author(s):

◽

Margaret Heinichen

Keyword(s):

Food Web ◽

Narragansett Bay ◽

Temperature Dependent ◽

Fish Bioenergetics ◽

Food Web Model

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Functional diversity alters the effects of a pulse perturbation on the dynamics of tritrophic food webs

10.1101/2021.03.22.436420 ◽

2021 ◽

Author(s):

Ruben Ceulemans ◽

Laurie Anne Myriam Wojcik ◽

Ursula Gaedke

Keyword(s):

Food Web ◽

Food Webs ◽

Functional Diversity ◽

Feedback Loop ◽

Environmental Changes ◽

Biodiversity Loss ◽

Trophic Levels ◽

Nutrient Pulse ◽

Trade Offs ◽

Food Web Model

Biodiversity decline causes a loss of functional diversity, which threatens ecosystems through a dangerous feedback loop: this loss may hamper ecosystems' ability to buffer environmental changes, leading to further biodiversity losses. In this context, the increasing frequency of climate and human-induced excessive loading of nutrients causes major problems in aquatic systems. Previous studies investigating how functional diversity influences the response of food webs to disturbances have mainly considered systems with at most two functionally diverse trophic levels. Here, we investigate the effects of a nutrient pulse on the resistance, resilience and elasticity of a tritrophic---and thus more realistic---plankton food web model depending on its functional diversity. We compare a non-adaptive food chain with no diversity to a highly diverse food web with three adaptive trophic levels. The species fitness differences are balanced through trade-offs between defense/growth rate for prey and selectivity/half-saturation constant for predators. We showed that the resistance, resilience and elasticity of tritrophic food webs decreased with larger perturbation sizes and depended on the state of the system when the perturbation occured. Importantly, we found that a more diverse food web was generally more resistant, resilient, and elastic. Particularly, functional diversity dampened the probability of a regime shift towards a non-desirable alternative state. In addition, despite the complex influence of the shape and type of the dynamical attractors, the basal-intermediate interaction determined the robustness against a nutrient pulse. This relationship was strongly influenced by the diversity present and the third trophic level. Overall, using a food web model of realistic complexity, this study confirms the destructive potential of the positive feedback loop between biodiversity loss and robustness, by uncovering mechanisms leading to a decrease in resistance, resilience and elasticity as functional diversity declines.

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