Haque Md Ayenuddin, Raka Rayhana Akhtar, Ali Md Raihan, Uddin Md Jasim, Mondol Md Mostafizur Rahman
Department of Oceanography and Blue Economy, Faculty of Fisheries, Habiganj Agricultural University, Habiganj, 3300, Bangladesh.
Department of Fisheries, University of Rajshahi, Rajshahi, 6205, Bangladesh.
Heliyon. 2024 Oct 28;10(21):e39916. doi: 10.1016/j.heliyon.2024.e39916. eCollection 2024 Nov 15.
Freshwater mussel is an ecologically important species endemic to south-east Asia, which has been suffering from a dramatic decline in recent years. The present study investigated the population dynamics and reproductive strategy of in a changing climate of Bangladesh waters. Mussels were sampled monthly from January to December 2021 from the Padma River near the Rajshahi city of Bangladesh. A total of 809 specimens were collected with a sizes ranging from 36.07 to 101.41 mm shell length and 7.92-87.54 g weight, respectively. The mussels displayed a growth pattern characterized by negative allometry in body weight-shell length relationship. The asymptotic length () was 106.05 mm, the growth coefficient () was 0.370 per year, and the growth performance index () was 3.58. The recruitment of was occurred throughout the year, with a peak during the month of February. The annual total mortality () was 1.15, and natural mortality () and fishing mortality () were 0.61 and 0.54 per year, respectively. The exploitation level was = 0.47 which indicates a state of under exploitation. Sex was identifiable throughout the study period and the sex ratio of the mussels did not differ significantly from the 1:1 (M: F) ratio (( = 15.80, P > 0.05). In terms of gonadal development, maturation, and spawning activity, both sexes had similar trends. Histology identified five gonad development stages for both male and female mussels: early developing, late developing, ripe, spawning, and spent. Monthly GSI data showed significant seasonal fluctuations with the highest GSI in April and it was sharply declined in May indicating the peak spawning of the mussels, which was in consistent with condition index and gonadal histology. All the physicochemical parameters showed significant variation except for pH. The most important factors explaining mussel body condition ( value) and reproductive strategies (GSI and CI) were water temperature, dissolved oxygen and water level. Although no known major threats of this species have been documented from Bangladesh, conservation measures could be adopted to protect the natural habitats of from adverse physicochemical and hydrological factors.
淡水贻贝是东南亚特有的具有重要生态意义的物种，近年来其数量急剧下降。本研究调查了孟加拉国水域气候变化下淡水贻贝的种群动态和繁殖策略。2021年1月至12月每月从孟加拉国拉杰沙希市附近的帕德玛河采集贻贝样本。共收集了809个样本，壳长范围为36.07至101.41毫米，体重范围为7.92至87.54克。贻贝呈现出体重与壳长关系为负异速生长的生长模式。渐近长度（L∞）为106.05毫米，生长系数（K）为每年0.370，生长性能指数（Ø）为3.58。淡水贻贝全年都有补充，2月为高峰期。年总死亡率（Z）为1.15，自然死亡率（M）和捕捞死亡率（F）分别为每年0.61和0.54。开发率E = 0.47，表明处于未充分开发状态。在整个研究期间都可以识别性别，贻贝的性别比例与1:1（雄:雌）比例没有显著差异（χ² = 15.80，P > 0.05）。在性腺发育、成熟和产卵活动方面，两性具有相似的趋势。组织学确定了雄性和雌性贻贝的五个性腺发育阶段：早期发育、晚期发育、成熟、产卵和耗尽。每月的性腺成熟度指数（GSI）数据显示出明显的季节性波动，4月GSI最高，5月急剧下降，表明贻贝产卵高峰期，这与状况指数和性腺组织学一致。除pH外，所有理化参数均显示出显著变化。解释贻贝身体状况（Condition value）和繁殖策略（GSI和CI）的最重要因素是水温、溶解氧和水位。尽管孟加拉国尚未记录到该物种已知的主要威胁，但可以采取保护措施来保护淡水贻贝的自然栖息地免受不利的理化和水文因素影响。
