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Journal Articles - UP - MSI

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

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AGROVOC Keyword: search.filters.agrovoc.population dynamicsSDG: search.filters.sdg.SDG 14 - Life below water

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    Age, growth, and population structure of Conomurex luhunuas
    Sanchez-Escalona, Katherine; Aliño, Porfirio (National Fisheries Research and Development Institute, 2022-12)
    Age and growth dynamics of Conomurex luhuanus were investigated to determine the population structure. Age-specific change in shell shape determined with geometric morphometrics revealed discrimination of shape between 0-3 years old at 99–100% while 3–4 years old can be separated with 81% certainty. Using the age discrimination data, K and L∞ were estimated at 1.00 year and 7.28 cm, respectively. Recruitment is bimodal with natural mortality (M) of 0.71 and fishing mortality (F) approximated at 3.92 year. The exploitation rate (E) is 0.85 year, indicating probable overharvesting of the population under study. The presence of a deep-water population, age-specific burying behavior, and bimodal recruitment pattern are possible resilience factors.
    The study was supported by a grant from PCAARRD-DOST.
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    Strong genetic structure and limited gene flow among populations of the tropical seagrass Thalassia hemprichii in the Philippines
    Nakajima, Yuichi; Matsuki, Yu; Fortes, Miguel D.; Uy, Wilfredo H.; Campos, Wilfredo L.; Nadaoka, Kazuo; Lian, Chunlan (MDPI AG, 2023-02-05)
    Seagrasses are marine angiosperms, and seagrass beds maintain the species diversity of tropical and subtropical coastal ecosystems. For proper understanding, management and conservation of coastal ecosystems, it is essential to understand seagrass population dynamics. Population genetic studies can cover large geographic scales and contribute to a comprehensive understanding of reproductive dynamics and potential dispersal among locations. The clonal and genetic diversity and genetic connectivity of Thalassia hemprichii in the Philippines were estimated by a population genetics approach. The geographic scale of this study has a direct distance of approximately 1600 km. Although high clonal diversity was found in some sites (R = 0.07–1.00), both sexual and asexual reproduction generally maintains separate populations. Genetic diversity is not definitely correlated with latitude, and genetic differentiation is significant in all pairs of sites (FST = 0.026–0.744). Complex genetic structure was found in some regions, even at a fine geographic scale. The migration of fruits and seedlings was elucidated as an infrequent and stochastic event. These results suggest the necessity for the conservation of this species due to a deficiency in migrants from external regions.
    We thank members of CECAM project.
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    Calanoides acutus in Gerlache Strait, Antarctica II. Solving an inverse problem in population dynamics
    Huntley, M. E.; Zhou, M.; Lopez, M. D. G. (Elsevier, 1994-01)
    A population dynamics model of the overwintering Southern Ocean copepod, Calanoides acutus, was constructed based on field observations of abundance in the Gerlache Strait during November 1989. We used an analytical solution to solve an inverse problem to determine rates of stage-specific mortality and development as the population emerged from overwintering diapause. Model predictions of mortality rates for CIV, CV and CVI copepodites were 0.068, 0 and 0.131 day−1, respectively. Best fit solutions of the model predict that late-stage copepodites emerge from diapause by “pulse moulting;” overwintering copepodites appear to emerge from diapause en masse in a relatively brief period prior to the annual spring bloom, rather than moulting at the comparatively slow rates observed in summer. We suggest that the modelling approach we used may have application to many species of copepods whose populations overwriter.