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Dobson, J. Y.

Publications and source records attributed to Dobson, J. Y..

2 recordsLinked to original sources

Modelling the invasion, management strategies and economic impact of the invasive alien aquatic plant Egeria densa

Egeria densa is a south American aquatic plant considered as an invasive alien species with a very aggressive and expansionist behaviour out of its native ecosystems. The widespread decorative use of E. densa in aquariums, coupled with the potential for subsequent disposal malpractice, has resulted in its introduction into a range of vulnerable ecosystems across the globe. This work presents a dynamic model of a population of E. densa based on its accidental introduction into an ecosystem in southeastern Spain. The model allows the simulation of colonisation process and management and disposal strategies. The model considers the influence of environmental variables such as temperature, light and water turbidity on the growth of the species. Among the management strategies tested, the optimal appears to be those of a preventive nature before the plant spreads, given that the costs of removal will be very high at that stage, and with high ecological impacts.

ecology↗

Integrating complexity in population modelling: from matrix to dynamic models using the jellyfish Carybdea marsupialis

Matrix models are widely used in population ecology studies and are valuable for analysing population dynamics. Nonetheless, this approach is somewhat rigid in terms of generating complex scenarios. Starting from the values of the transition matrix, we can build a dynamic model to incorporate more biological-based reality into the model (e.g. polyp stage) and provide a higher flexibility in generating scenarios. As an example, we used the transition matrix calculated for a time series data of a population of the box jellyfish Carybdea marsupialis (L. 1758) in the Western Mediterranean in a previously published study. Dynamic models can help us to better understand the complex relationships that drive populations, test different hypotheses and compare scenarios. The dynamic model was developed in STELLA Architect, calibrated and optimised and it has been used to simulate various scenarios of ecological interest, including a decline in food supply, jellyfish removal strategies, changes in drift currents and changes in substrate availability for planulae to settle. A sensitivity analysis showed that polyp strobilation rate and strobilation pattern were two of the most sensitive variables. This matrix-to-dynamic model approach could be useful to integrate more biological complexity into population models and, in turn, obtain a better fit to the field data.

ecology↗