Exploring Lake Victoria ecosystem functioning using the Atlantis modeling framework

Nyamweya, Chrisphine S.; Sturludóttir, Erla; Tómasson, Tumi; Fulton, Elizabeth A.; Taabu‐Munyaho, Anthony; Njiru, M.; Stefansson, Gunnar

doi:10.1016/j.envsoft.2016.09.019

Cited by 32 publications

(13 citation statements)

References 32 publications

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“…The perch biomass in the lake started to decline by 1990, due largely to the exhaustion of its prey, and intense fishing pressure driven by an emergent lucrative export market (Nyamweya et al . ). There has been a resurgence of the native species in the recent past, being attributed among other factors to the decline in the predatory Nile perch (Fig.…”

Section: Ecological Impacts Of Nile Perchmentioning

confidence: 97%

Impacts of Nile Perch, Lates niloticus, introduction on the ecology, economy and conservation of Lake Victoria, East Africa

Aloo¹,

Njiru

Balirwa

et al. 2017

Lakes & Reservoirs

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Nile perch were secretly introduced into Lake Victoria in the 1950s, and officially in the 1960s, amid unresolved controversy. Proponents were of the view that the introduction would improve fisheries production and sport fishing. Although the former objective was achieved, the side effects were dire, including extinction of many native species, especially the ecologically important haplochromines, because of predation. The introduction also changed the habitat, trophic dynamics and water clarity. The change in water clarity is thought to be responsible for hybridization of haplochromines, further contributing to the loss of species diversity among cichlids. The establishment and expansion of the Nile perch also altered the fishery and socio‐economic settings characterizing the lake. A local economy which, until the early 1980s, was based on native fish species has been replaced by an export‐oriented exotic fish processing industry that destroyed the once‐cherished traditional resource. Other socio‐economic issues associated with Nile perch include the high HIV/AIDS prevalence among fishers, and border conflicts attributable to the migratory and transboundary nature of the fishery resource. Conservation measures for the fishery should include establishment of co‐management units that have so far registered both successes and challenges. Other efforts include establishment of the Nile perch Fisheries Management Plans that focus on curbing overfishing and eradicating illegal fishing.

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Section: Ecological Impacts Of Nile Perchmentioning

confidence: 97%

Impacts of Nile Perch, Lates niloticus, introduction on the ecology, economy and conservation of Lake Victoria, East Africa

Aloo¹,

Njiru

Balirwa

et al. 2017

Lakes & Reservoirs

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“…Nonetheless, even slow-running Atlantis simulations and other dynamic models can be compared against standardized data sets (e.g. time series of predator and prey abun-dance) to evaluate model fit to data (see Atlantis examples such as Nyamweya et al 2016, Olsen et al 2016. Model fit, for instance in a MICE, can be expressed as the probability of the model given the data, which can be used to weight models for prediction (Ianelli et al 2016).…”

Section: Next Stepsmentioning

confidence: 99%

A multi-model approach to understanding the role of Pacific sardine in the California Current food web

Kaplan¹,

Francis²,

Punt³

et al. 2019

Mar. Ecol. Prog. Ser.

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We develop a multi-model approach to explore how abundance of a forage fish (Pacific sardine Sardinops sagax) impacts the ecosystem and predators in the California Current, a region where sardine and anchovy Engraulis mordax have recently declined to less than 10% of contemporary peak abundances. We developed or improved applications of 3 ecosystem modeling approaches: Ecopath, Model of Intermediate Complexity for Ecosystem assessment (MICE), and Atlantis. We also used Ecopath diets to predict impacts to predators using a statistical generalization of the dynamic Ecosim model (Predator Response to the Exploitation of Prey [PREP]). Models that included brown pelican Pelecanus occidentalis at the species level (MICE and Ecopath/PREP) both predict moderate to high vulnerability of brown pelicans to low sardine abundance. This vulnerability arises because sardine comprises a large fraction of their diet, and because other important prey (anchovy) also exhibit large population fluctuations. Two of the ecosystem models (MICE and Atlantis) suggest that California sea lions Zalophus californianus exhibit relatively minor responses to sardine depletion, due to having broader diets and lower reliance on another fluctuating species, anchovy. On the other hand, Ecopath/PREP suggests that sardine declines will have a stronger impact on California sea lions. This discrepancy may in part reflect structural differences in the models: Atlantis and MICE explicitly represent density dependence and age-structure, which can mitigate effects of prey depletion in these models. Future work should identify fisheries management strategies that are robust to uncertainties within and among models, rather than relying on single models to assess ecosystem impacts of management and forage fish abundance. KEY WORDS: Forage fish • Pacific sardine • California Current • Ecosystem model • California sea lion • Brown pelican • Multi-model approach Contribution to the Theme Section 'Drivers of dynamics of small pelagic fish resources: biology, management and human factors'

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“…The technical specifications of the Atlantis framework, including process equations, can be found in Fulton (2001) and Fulton et al (2004aFulton et al ( ,b, 2011. Further information can also be found on the Atlantis wiki 1 and published model applications (i.e., Smith et al, 2015;Nyamweya et al, 2016). Briefly, the Atlantis code base is structured in submodels that can be selectively implemented, including ecology, fisheries, monitoring, assessment, and management.…”

Section: Atlantis Ecosystem Modeling Frameworkmentioning

confidence: 99%

Ocean Futures Under Ocean Acidification, Marine Protection, and Changing Fishing Pressures Explored Using a Worldwide Suite of Ecosystem Models

et al. 2018

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Ecosystem-based management (EBM) of the ocean considers all impacts on and uses of marine and coastal systems. In recent years, there has been a heightened interest in EBM tools that allow testing of alternative management options and help identify tradeoffs among human uses. End-to-end ecosystem modeling frameworks that consider a wide range of management options are a means to provide integrated solutions to the complex ocean management problems encountered in EBM. Here, we leverage the global advances in ecosystem modeling to explore common opportunities and challenges for ecosystem-based management, including changes in ocean acidification, spatial management, and fishing pressure across eight Atlantis (atlantis.cmar.csiro.au) end-toend ecosystem models. These models represent marine ecosystems from the tropics to the arctic, varying in size, ecology, and management regimes, using a three-dimensional, spatially-explicit structure parametrized for each system. Results suggest stronger impacts from ocean acidification and marine protected areas than from altering fishing pressure, both in terms of guild-level (i.e., aggregations of similar species or groups) biomass and in terms of indicators of ecological and fishery structure. Effects of ocean acidification were typically negative (reducing biomass), while marine protected areas led to both "winners" and "losers" at the level of particular species (or functional groups). Changing fishing pressure (doubling or halving) had smaller effects on the species guilds Olsen et al. Ocean Futures Explored Using Models or ecosystem indicators than either ocean acidification or marine protected areas. Compensatory effects within guilds led to weaker average effects at the guild level than the species or group level. The impacts and tradeoffs implied by these future scenarios are highly relevant as ocean governance shifts focus from single-sector objectives (e.g., sustainable levels of individual fished stocks) to taking into account competing industrial sectors' objectives (e.g., simultaneous spatial management of energy, shipping, and fishing) while at the same time grappling with compounded impacts of global climate change (e.g., ocean acidification and warming).

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Exploring Lake Victoria ecosystem functioning using the Atlantis modeling framework

Cited by 32 publications

References 32 publications

Impacts of Nile Perch, Lates niloticus, introduction on the ecology, economy and conservation of Lake Victoria, East Africa

Impacts of Nile Perch, Lates niloticus, introduction on the ecology, economy and conservation of Lake Victoria, East Africa

A multi-model approach to understanding the role of Pacific sardine in the California Current food web

Ocean Futures Under Ocean Acidification, Marine Protection, and Changing Fishing Pressures Explored Using a Worldwide Suite of Ecosystem Models

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