A qualitative model of limiting factors for a salmon life cycle in the context of river rehabilitation

Qualitative Reasoning modelling has been promoted as a tool for formalising, integrating and exploring conceptual knowledge in ecological systems, such as river rehabilitation, which draw different information from multiple domains. A qualitative model was developed in Garp3 to capture and formalise knowledge about river rehabilitation and the management of an Atlantic salmon population, for use in an educational setting. The model integrated information about the ecology of the salmon life cycle, the environmental factors that may limit the survival of key life stages and their links with human activities such as agriculture, habitat rehabilitation and fishing. Whilst the compositional approach to qualitative modelling allowed simple representation of component concepts, the successful integration of these components in simulations of complex scenarios required a number of abstract representations, assumptions and technical modelling solutions to handle aspects of ambiguity and complexity, and to obtain the desired system behaviour. The final scenarios and simulations produced were able to represent river rehabilitation concepts in the context of a complete life cycle, but at this scale processing the simulations was very time consuming. Therefore, to handle this complexity an additional series of smaller demonstrator scenarios was developed that succinctly explored individual concepts within the system. This study indicates that qualitative modelling may be a valuable tool for exploring large systems, provided suitable means can be used to handle complexity and ambiguity. © 2009 Elsevier B.V. All rights reserved

O uso de modelos de raciocínio qualitativo para investigar a teoria e a dinâmica de metapopulações

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Ecologia, 2011É preciso entender melhor a dinâmica de populações, diante da aceleração e da intensificação das mudanças em paisagens naturais. Um conjunto de modelos qualitativos foi desenvolvido nos softwares Garp 3 (www.garp3.org) e DynaLearn (www.dynalearn.eu) com o objetivo de sintetizar e formalizar o conhecimento sobre a biologia das populações resumido pela teoria de Metapopulações. A modelagem qualitativa é considerada uma ferramenta para a integração e exploração do conhecimento conceitual de sistemas ecológicos e também da dinâmica de populações. Três abordagens foram modeladas para explicar o comportamento de metapopulações: 1) o conceito clássico desenvolvido por Levins; 2) a proposta de Pulliam sobre metapopulações do tipo fonte-sumidouro; e 3) o modelo integrado de conservação, que teve como base as idéias de Ilkka Hanski. Esses modelos resumem o desenvolvimento de idéias incorporadas à base da teoria de metapopulações e são úteis para comparar hipóteses e pressupostos envolvidos nos diferentes pontos de vista sobre esse tema. Os modelos têm por objetivo responder: ‘Como funcionam os principais processos ecológicos capazes de explicar a estrutura e a dinâmica de metapopulações?´. Para que uma população seja considerada metapopulação, a existência de um balanço entre as forças migratórias e de extinção deve estar presente, assim como a influência da permeabilidade da matriz e da qualidade de habitat, as quais afetam a comunicação entre os fragmentos de população. Este estudo também investigou, com o apoio de modelos baseados em raciocínio qualitativo, o impacto do uso de modelos conceituais no entendimento das relações de causalidade relacionados à biologia de populações, metapopulações e outras questões relacionadas à biologia da conservação. Os resultados mostram que os modelos qualitativos são ferramentas valiosas para explorar a dinâmica de metapopulações e promover o melhor entendimento sobre cenários de maior complexidade nos quais se aplicam diferentes restrições sobre flutuações populacionais no tempo e no espaço. _______________________________________________________________________________________ ABSTRACTA better understanding on population dynamics is needed in face of the accelerating changes and modification on natural landscapes. A set of qualitative models were developed in Garp3 (www.garp3.org) and DynaLearn (www.dynalearn.eu) to capture and formalize knowledge about population biology summarized by the Metapopulation theory. Qualitative Reasoning modeling has been considered as a tool for integration and exploration of conceptual knowledge in ecological systems and population dynamics. Three types of approaches to explain metapopulation behavior were modeled: 1) the classical concept developed by Levins; 2) Pulliam’s view on source and sink populations; and 3) an integrated model of conservation, based on I. Hanski ideas. These models summarize the development of ideas incorporated to the basis of metapopulation theory and are useful for comparing hypotheses and assumptions involved in different viewpoints. These models aim to answer the question: “How the main ecological processes can explain metapopulation structure and dynamics?” The most fundamental message from taking a metapopulation perspective is that it can be recognized as a result of the balance between emigration and extinction forces, considering the influence of conservation and landscape ecology elements, like the matrix permeability and patch quality, that affect the communication between the fragments of population. This study also investigated the impact of conceptual modeling on the understanding of the causality relations related to population biology, metapopulation and conservation issues. The results show that qualitative models are a valuable tool for exploring metapopulation dynamics providing better understanding of complex scenarios dealing with constraints on population fluctuations over time and space

Processos ecológicos em zonas ripárias : o efeito da integridade da vegetação ripária sobre as comunidades aquáticas em riachos de cabeceira

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Ecologia, 2013.Apesar da elevada biodiversidade encontrada no Cerrado brasileiro, o crescimento populacional e a atividade humana têm afetado diretamente os ambientes naturais, sobretudo os cursos d’água. Uma das principais dificuldades encontradas em frear esse processo de degradação é a falta de conhecimento de como os mecanismos naturais que operam esses sistemas, tais como a dinâmica de matéria orgânica e energia e as ligações tróficas entre o ecossistema terrestre e aquático, são afetados pela degradação. Por isso, reconhecer que efeitos da degradação, tanto para o ecossistema em si como para a biota, torna-se fundamental e está entre as principais questões em ecologia do século XXI. Nesse sentido, a modelagem qualitativa e o estudo de campo se mostraram complementares na obtenção de respostas quanto à esses efeitos. Os modelos proporcionaram a possibilidade de explorar de maneira heurística diferentes cenários e avaliar os efeitos da interferência humana nos ecossistemas. Enquanto isso, as observações obtidas em campo possibilitaram discutir como a integridade da vegetação ripária atua na seleção da biota em riachos de cabeceira, interferindo nos padrões de composição, estrutura e dieta da assembléia de peixes. Os resultados mostraram que a perda da vegetação, ou redução da integridade da zona ripária, tem efeito principalmente na composição de espécies, porém não alterando a composição da cadeia trófica das comunidades. As evidências obtidas são claras ao demonstrar que ambientes perturbados pela retirada da vegetação são permissivos ao estabelecimento de espécies oportunistas em função da redução de espécies mais sensíveis, devido sobretudo a dependência das espécies ao recurso alóctone. O impacto na vegetação ripária afetou a dieta das espécies, com maior proporção de itens alóctones consumidos por peixes em trechos impactados e menor nos riachos naturais. Os mesmos padrões tróficos funcionais foram observados nos modelos, que ainda mostraram que possíveis alternâncias nas condições tróficas podem ser observadas em riachos naturais sazonalmente devido a variações nos fluxos de energia e matéria. Os resultados contribuíram ainda para indicar potenciais relações ecológicas em riachos de cabeceira e demonstram o potencial do uso de modelos qualitativos como ferramenta para investigar os efeitos da atividade humana sobre os processos ecológicos e a biota

Implications of small-scale run-of-river hydropower schemes on fish populations in Scottish streams

In the past few years there has been a resurgence of interest in hydropower as a direct consequence of the UK government’s commitment to renewable energy and associated financial incentives. The majority of new schemes are run-of-river, which have no significant storage of water, the turbine only making use of the available flow at the site. Hydropower is often presented as a clean and renewable energy, and thus portrayed as having no negative impacts on the environment. However this description has been challenged by numerous authors who consider the impacts on fish and other biota as significant, particularly on salmonid fish populations in relation to migration.This study investigated the implications of small-scale run-of-river hydropower schemes on fish populations in Scottish streams. In these schemes, water is abstracted from an intake above a mall weir to drive a turbine before the water is returned to the watercourse at a downstream location. Abstracted water is channelled down a pipeline to the turbines in a powerhouse before release at the outfall position; this results in a depleted reach. The term “depleted reach” refers to the stretch of river between the intake and outfall of high-head run-of-river hydropower schemes that experiences reduced flow due to abstraction. The main impact in the depleted reach is a reduction in the amount of water, leading to associated changes in habitat including important spawning/nursery areas. The main impact upstream of the intake is reduced access because of the intake weir, which may be exacerbated by the reduction in the amount of water downstream. Therefore, impacts can be observed upstream of an intake (barrier effect), upstream and downstream of an intake (barrier and abstraction effect) and downstream of an intake (abstraction effect). In total, ten schemes were included within this study; five with extensive pre-and post-monitoring and a further five that were considered to have less extensive data. At Kinnaird Burn, Keltney Burn and Innerhadden Burn, salmonid populations varied over the study period. Densities of fish varied both within and outside the depleted reaches, therefore, the inter annual variations in salmonid densities made it difficult to detect any impacts, specifically in response to commissioning of the hydropower schemes, when comparing before/after and control/impact data, despite having extensive pre- and post-commissioning data. It was difficult to detect any impacts of the Ardvorlich Burn, Douglas Water, Camserney Burn and Allt Gleann Da-Eig hydropower schemes on fish densities due to the limitations of the data sets, including a lack of baseline and post-commissioning data and control sites to account for temporal and spatial variations in the fish populations. Consequently, confident conclusions could not be drawn. In the River Callop, 0+ salmonid densities declined at several sites in the depleted reach post hydropower commissioning. However, a lack of spatial and temporal data made it difficult to conclude whether the decline was in response to the hydropower scheme or natural variability. At Rottal Burn and Inverhaggernie Burn, a reduction in ≥1+ and 0+ salmon density respectively, was observed in the depleted reach, post hydropower commissioning. These declines were not reflected in the fish densities at the control site downstream of the depleted reach and thus suggest an impact of flow regulation.The meta-analysis of historical data and subsequent monitoring raised issues about the Environmental Impact Assessment strategies on some of the schemes. Therefore the concerns that existing sampling protocols and impact assessments are inadequate to provide robust, defensible information about the impact of small-scale run-of-river hydropower schemes on fisheries, was upheld. A proposed survey protocol was developed using Before After Control Impact analysis that is intended to answer this need and to be used in conjunction with appropriate guidance documents provided by the regulatory agencies, such as the Scottish Environment Protection Agency (2010) “Guidance for developers of run-of-river hydropower schemes” and the Environment Agency (2009a) “Good practice guidelines to the Environment Agency hydropower handbook”