In this paper, the influence of additive Allee effect in prey and periodic harvesting in predator to the dynamics of the Leslie-Gower predator-prey model is proposed. We first simplify the model to the non-dimensional system by scaling the variable and transform the model into an autonomous system. If the effect Allee is weak, we have at most two equilibrium points, else if the Allee effect is strong, at most four equilibrium points may exist. Furthermore, the behavior of the system around equilibrium points is investigated. In the end, we give numerical simulations to support theoretical results.
Abstract. Achmad DS, Gani S, Ardiansyah W, Mokoginta MM, Nurdin MS, Jompa J, Indrianti MA, Achmad N. 2022. Population dynamics of reef fish in the Kwandang Bay, Sulawesi Sea, Indonesia. Biodiversitas 23: 5217-5226. The grouper stocks in Kwandang Bay, Sulawesi Sea, Indonesia, are dominated by orange-spotted grouper (Epinephelus coioides) and coral trout (Plectropomus leopardus). However, the Kwandang Bay grouper fishery is currently experiencing serious challenges due to population decline resulting in a decline in both the average size of fish caught and the production volume. This study was conducted in Kwandang Bay, Sulawesi Sea, from January to December 2021. The population dynamics parameters estimated were growth, recruitment, mortality, exploitation rate and yield per recruit. The results showed that the total length (TL) of E. coioides and P. leopardus ranged from 16.50-101 cm and 17.90-60 cm, respectively, with Von Bertalanffy K-coefficients of 0.38 and 0.69, respectively. Recruitment occurred during most of the year, with respective recruitment value ranges of 0.99-17.11% and 0.08-19.22%. Natural and fishing mortality was 0.69/year-1 and 0.87/year-1 for E. coioides, 1.16/year-1 and 1.47/year-1 for P. leopardus. Beverton and Holt yield per recruit analysis indicated recruitment overfishing of both E. coioides and P. leopardus. Fishing regulations are needed to maintain a sustainable grouper fishery, including a 25% reduction in fishing vessels and gear, to enable the groupers of Kwandang Bay to spawn at least once during their life cycle.
Penelitian ini bertujuan untuk mendeskripsikan Penggunaan media e-learning dalam pembelajaran matematika di masa pandemi (Covid-19). Penelitian ini adalah penelitian deskriptif kuantitatif dengan populasi seluruh peserta didik kelas IX SMP N 4 Kota Gorontalo yang berjumlah 217 peserta didik. Sampel dalam penelitian sebanyak 22 orang. Teknik pengambilan sampel yaitu simple random sampling. Data penelitian diperoleh dari lembar pengamatan guru dan peserta didik terkait penggunaan media e-learning ( Zoom, Whatsapp, Google Classroom), tes hasil belajar angket respon peserta didik serta wawancara guru dan peserta didik tentang penggunaan media e-learning dalam pembelajaran matematika di masa pandemi. Hasil penelitian menunjukan bahwa penggunaan media e-learning dalam pembelajaran matematika di masa pandemi berada pada kategori kurang baik yang ditunjukan dengan Kegiatan Guru memperoleh rata-rata presentase 54,4%, kegiatan Peserta didik memperoleh rata-rata 60%, respon peserta didik memperoleh rata-rata 73,6%, dan tes hasil belajar presentase peserta didik yang tuntas adalah 45.4% dan peserta didik yang tidak tuntas sebesar 54,5%.
This study aims to describe students' mathematics learning outcomes through online learning for the 2019/2020 academic year on the subject of flat-sided space geometry. This descriptive study was conducted at SMP Negeri 5 Paguyaman involving 28 students of class VIII as a sample selected using the purposive sampling technique. Data collection techniques in this study were tests in the form of multiple-choice questions and student response questionnaires. The results of the research that refer to the cognitive domain of the revised Bloom taxonomy by Anderson and Krathwohl show that the C1 cognitive domain is remembering, the ability of students to remember, recognize or know a concept of the material being asked in the questions given an average of 77.36% is in a good category. C2 cognitive domain is understanding; students' ability to understand the material on average 35.75% is in the poor category. C3 cognitive realm applies, on this indicator, students' ability to apply the formula to the questions given an average of 17.85% is in the poor category. C4 cognitive domain analyzes students' ability to analyze the average question is 39.70% who are in the poor category. With the average percentage of all cognitive domains, namely 45.71%, students' mathematics learning outcomes through online learning on the subject of flat-side space geometry is still in the low category, and learning using Facebook Messenger has not provided maximum results.
Highlight Research There are 26 species identified to be originated from the bay, which the highest diversity in Indonesia Six species found in Kwandang Bay is showing trends of decreasing populations and two species vulnerable based on IUCN conservation list Growth model and Fulton condition factor determined for 14 species indicates that they live in a good state of well beings in the bay The models and condition factors also reflect the adequate food resources required for grouper growth which makes Kwandang Bay as a good habitat for groupers Abstract Grouper fishery has been the source of income for 3,700 fishermen in Kwandang Bay. Since 2017, grouper populations in Kwandang have been depleting due to the absence of management. This research aimed to analyze species composition, length-weight relationship, and condition factor of the groupers. Samples were collected from fishers who caught the fish using traps, speargun, and handline. Samples were identified through a method by Heemstra and Randall, while the length-weight relationship was estimated using log-linear regression and t-test. The number of specimens identified during January - December 2021 was 1,571 individuals. Research showed that those samples consisted of 26 species under eight genera. Six species found in Kwandang Bay were showing trends of decreasing populations and two species were vulnerable based on the IUCN conservation list. Length-weight relationship analysis of 14 grouper species resulted in b value ranging from 1.6359 to 3.4417 and R2 ranges from 0.7718 to 0.9858. A significant test at a 95% confident interval showed that 14 species had an isometric growth pattern. Fulton condition factors show that Kwandang Bay is an essential habitat for groupers, and the bay can support the fish growth due to the adequate food availability.
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