Use of an Inverse Method for Time Series to Estimate the Dynamics of and Management Strategies for the Box Jellyfish Carybdea marsupialis

PLOS ONE, Dec 2019

Frequently, population ecology of marine organisms uses a descriptive approach in which their sizes and densities are plotted over time. This approach has limited usefulness for design strategies in management or modelling different scenarios. Population projection matrix models are among the most widely used tools in ecology. Unfortunately, for the majority of pelagic marine organisms, it is difficult to mark individuals and follow them over time to determine their vital rates and built a population projection matrix model. Nevertheless, it is possible to get time-series data to calculate size structure and densities of each size, in order to determine the matrix parameters. This approach is known as a “demographic inverse problem” and it is based on quadratic programming methods, but it has rarely been used on aquatic organisms. We used unpublished field data of a population of cubomedusae Carybdea marsupialis to construct a population projection matrix model and compare two different management strategies to lower population to values before year 2008 when there was no significant interaction with bathers. Those strategies were by direct removal of medusae and by reducing prey. Our results showed that removal of jellyfish from all size classes was more effective than removing only juveniles or adults. When reducing prey, the highest efficiency to lower the C. marsupialis population occurred when prey depletion affected prey of all medusae sizes. Our model fit well with the field data and may serve to design an efficient management strategy or build hypothetical scenarios such as removal of individuals or reducing prey. TThis This sdfsdshis method is applicable to other marine or terrestrial species, for which density and population structure over time are available.

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Use of an Inverse Method for Time Series to Estimate the Dynamics of and Management Strategies for the Box Jellyfish Carybdea marsupialis

September Use of an Inverse Method for Time Series to Estimate the Dynamics of and Management Strategies for the Box Jellyfish Carybdea marsupialis Cesar Bordehore 0 1 Verónica L. Fuentes 0 1 Jose G. Segarra 0 1 Melisa Acevedo 0 1 Antonio Canepa 0 1 Josep Raventós 0 1 0 1 Department of Ecology and Multidisciplinary Institute for Environmental Studies “Ramon Margalef”, University of Alicante , Alicante , Spain , 2 Institute of Marine Sciences , CSIC, Barcelona , Spain 1 Editor: Judi Hewitt, University of Waikato (National Institute of Water and Atmospheric Research), NEW ZEALAND Frequently, population ecology of marine organisms uses a descriptive approach in which their sizes and densities are plotted over time. This approach has limited usefulness for design strategies in management or modelling different scenarios. Population projection matrix models are among the most widely used tools in ecology. Unfortunately, for the majority of pelagic marine organisms, it is difficult to mark individuals and follow them over time to determine their vital rates and built a population projection matrix model. Nevertheless, it is possible to get time-series data to calculate size structure and densities of each size, in order to determine the matrix parameters. This approach is known as a “demographic inverse problem” and it is based on quadratic programming methods, but it has rarely been used on aquatic organisms. We used unpublished field data of a population of cubomedusae Carybdea marsupialis to construct a population projection matrix model and compare two different management strategies to lower population to values before year 2008 when there was no significant interaction with bathers. Those strategies were by direct removal of medusae and by reducing prey. Our results showed that removal of jellyfish from all size classes was more effective than removing only juveniles or adults. When reducing prey, the highest efficiency to lower the C. marsupialis population occurred when prey depletion affected prey of all medusae sizes. Our model fit well with the field data and may serve to design an efficient management strategy or build hypothetical scenarios such as removal of individuals or reducing prey. TThis This sdfsdshis method is applicable to other marine or terrestrial species, for which density and population structure over time are available. - Funding: This research was carried out under contract LIFE 08 NAT ES 0064 (to CB and VLF) cofinanced by the European Commission (www. cubomed.eu), the Ministerio de Agricultura, Alimentación y Medio Ambiente, the Dirección General del Agua of the Regional Government of Valencia and the Fundación Biodiversidad. This work was also partially supported by Spanish Ministry of Education and Science co-funded by FEDER Population ecology of marine organisms commonly uses a descriptive approach in which their sizes and densities are plotted over time. This approach is valid for understanding what has program (CGL2012-31668) to JR. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. occurred in the past, but it has limited usefulness for design strategies in management or modelling to anticipate plausible or theoretical scenarios. Population projection matrix models are among the most widely used tools in ecology. A robust body of literature has discussed the merits of demographic models, particularly in the context of their utility for management (reviewed in Crone et al. [1]). For the majority of pelagic marine organisms and some terrestrial species, it is difficult or even impossible to mark individuals and follow them over time to determine their vital rates and build a population projection matrix model. Nevertheless, it is possible to sample periodically to calculate population size structure and densities. Such time-series density data can be used to determine the parameters of a population projection matrix model, as we have done here for the box jellyfish Carybdea marsupialis (Linnaeus, 1758). This approach is known as an “inverse problem” [2], unlike the traditional modelling approach, a “forward problem”, that predicts the dynamics from the model and the initial conditions [3]. This inverse approach has rarely been used on aquatic organisms. Two exceptions are Katsanevakis & Verriopoulos [4], who modelled Octopus vulgaris in the eastern Mediterranean Sea, and Erwin et al. [5], who modelled the invasion of the aquatic plant Alternanthera philoxeroides. To our knowledge, this approach has never been used for jellyfish. Cubozoans, or box jellyfish, are the smallest class of Cnidaria, with only about 50 species [6], which occur in tropical and subtropical waters. Cubozoans are of great biological and social importance [6] because they are active fish and zooplankton predators [7–9], they have complex eyes an (...truncated)


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Cesar Bordehore, Verónica L. Fuentes, Jose G. Segarra, Melisa Acevedo, Antonio Canepa, Josep Raventós. Use of an Inverse Method for Time Series to Estimate the Dynamics of and Management Strategies for the Box Jellyfish Carybdea marsupialis, PLOS ONE, 2015, 9, DOI: 10.1371/journal.pone.0137272