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Journal Articles - UP - MSI

Permanent URI for this collectionhttps://repository.unesco.gov.ph/handle/123456789/50

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    Insights into the environmental conditions contributing to variability in the larval recruitment of the tropical sardine Sardinella lemuru
    Pata, Patrick R.; Yñiguez, Aletta T.; Deauna, Josephine Dianne L.; De Guzman, Asuncion B.; Jimenez, Cesaria R.; Rosario, Roselle T. Borja-Del; Villanoy, Cesar L. (Elsevier, 2021-07)
    The small pelagic fishery in the southern Philippines is one of the largest contributors to fisheries production in the country, and is dominated by the Bali sardine Sardinella lemuru. This species is a year-round spawner that has its peak spawning period during the northeast monsoon (NEM) months of November to February. However, there is still limited information on the conditions that affect this species’ survival during its early life history stages. Here, we attempt to discern the importance of temperature, prey density and advection on sardine larvae. The larvae were represented as passive particles that were released in known spawning grounds to simulate dispersal. The conditions the larvae experienced, namely, temperature and estimated prey density based on satellite chlorophyll-a values were recorded at each time step until the estimated recruitment age of 60 days. The temporal and spatial averaged conditions of recruited sardines showed that sardines spawned during the NEM months experienced higher chlorophyll-a, lower (more optimal) sea surface temperature, albeit higher advective loss, than sardines spawned during other months. Comparisons between years showed that during higher reported catch years, sardine larvae experienced lower temperatures and higher retention nearshore. Our results emphasize that sardine stock management efforts need to recognize the contribution of the temporally variable sardine environment to patterns in sardine recruitment and consequently in catches.
    The authors would like to thank Dr. Wilfredo Campos, Luke Felix, Dr. Rio Naguit, Denmark Recamara, and the Research for Sardines Volunteer Program (RSVP) volunteers for sharing sardine fisheries data; Arjay Cayetano for helping start the model used; and Iris Salud Bollozos for useful insights on larval ecology. This study was fully funded by the Department of Science and Technology–Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOSTPCAARRD) under the program, “Development of robust tools for managing sardine fisheries in the Philippines: Zamboanga Upwelling Bohol Sea System Program.” The authors declare no conflict of interest.
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    Spatial planning insights for Philippine coral reef conservation using larval connectivity networks
    Pata, Patrick R.; Yñiguez, Aletta T. (Frontiers Media SA, 2021-10-06)
    The marine habitats of the Philippines are recognized to be some of the most biodiverse systems globally yet only 1.7% of its seas are designated as marine protected areas (MPAs) with varying levels of implementation. Many of these MPAs were established based on local-scale conservation and fisheries objectives without considering larger-scale ecological connections. The connectivity of reefs through larval dispersal is important in the regional-scale resilience against anthropogenic disturbances and is considered a significant criterion in planning for MPAs. In this study, we provide insights into the delineation of ecologically connected MPA networks using larval dispersal modeling and network analysis. We characterized the network properties of the Philippine coral reefs, organized as 252 reef nodes, based on the larval connectivity networks of a branching coral, sea urchin, and grouper. We then evaluated the distribution of the existing 1,060 MPAs relative to the connectivity patterns. All reef nodes were found to be highly interconnected with a mean shortest path ranging from 1.96 to 4.06. Reef nodes were then ranked according to their relative importance in regional connectivity based on five connectivity indices. Despite the between-organism and between-index variability in rankings, there were reefs nodes, mostly located offshore and at major straits, which consistently ranked high. We found that the distribution of existing MPAs partially capture some of the regional connectivity functions but there is a spatial mismatch between the primarily coastal MPAs and the high-ranking reef nodes. Furthermore, network partitioning identified subnetworks and dispersal barriers. The existing MPAs were found to be disproportionately distributed to a few subnetworks and that the largest subnetworks do not contain the greatest number of MPAs. Considering these gaps, we suggest expanding the coverage of protected areas especially in underrepresented reef networks to meaningfully capture national-scale connectivity and meet global conservation objectives.
    We would like to thank Dr. Vera Horigue and Andrew Torres for constructive comments and suggestions during the early versions of this paper. We also thank the members of the Biological Oceanography and Modeling of Ecosystems (BiOME) Laboratory who assisted in running model simulations.