In this study, we investigated the composition of the gill tissue relative to the reproductive status of the lucinid clam Loripes orbiculatus (sensus Poli, 1791) according to seasonal as well as biological parameters to provide insights into the physiological variability of this symbiotic bivalve. Temporal variation in population density was also studied. The species was investigated in Zostera noltii seagrass beds in the Thau lagoon (43°26′52.27′′ N, 3°39′6.25′′ E) in the south of France in a monthly sampling study from May 2013 to July 2015. A total of 257 individual adults of different sizes were analysed according to water temperature and salinity variations. The findings revealed a very stable Loripes density over time, with one single reproductive period during late spring/early summer. We also found that bacteriocytes and mucocytes in the gills were negatively correlated and highly variable in their respective proportions. Bacteriocytes remained dominant during cold periods, whereas mucocytes appeared mainly in the gills of large individuals when the water temperature increased in the spring. As mucocytes were also related with gonadal maturation, we hypothesize that these may allow the host to increase the proportion of heterotrophy in its nutrition during spring primary production to face the metabolic demands required for reproduction. It is possible that mucocytes may also be involved in host immunity.

中文翻译：

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Loripes orbiculatus 鳃（双壳类，Lucinidae）中粘液细胞和细菌细胞之间的权衡：对共生物种的季节性和生殖状态的混合营养适应？

在这项研究中，我们根据季节和生物参数调查了鳃组织的组成与 lucinid clampes orbiculatus (sensus Poli, 1791) 生殖状态的关系，以深入了解这种共生双壳类动物的生理变异性。还研究了人口密度的时间变化。2013 年 5 月至 2015 年 7 月，在法国南部 Thau 泻湖（北纬 43°26'52.27''，东经 3°39'6.25''）的海草床中对该物种进行了每月抽样研究。根据水温和盐度的变化，对总共 257 只不同大小的个体进行了分析。研究结果显示，随着时间的推移，Loripes 密度非常稳定，在春末/夏初只有一个繁殖期。我们还发现鳃中的细菌细胞和粘液细胞呈负相关，并且它们各自的比例变化很大。细菌细胞在寒冷时期仍然占优势，而当春季水温升高时，粘液细胞主要出现在大型个体的鳃中。由于粘液细胞也与性腺成熟有关，我们假设这些可能使宿主在春季初级生产期间增加其营养中的异养比例，以应对繁殖所需的代谢需求。粘液细胞也可能参与宿主免疫。而当春季水温升高时，粘液细胞主要出现在大型个体的鳃中。由于粘液细胞也与性腺成熟有关，我们假设这些可能使宿主在春季初级生产期间增加其营养中的异养比例，以应对繁殖所需的代谢需求。粘液细胞也可能参与宿主免疫。而当春季水温升高时，粘液细胞主要出现在大型个体的鳃中。由于粘液细胞也与性腺成熟有关，我们假设这些可能使宿主在春季初级生产期间增加其营养中的异养比例，以应对繁殖所需的代谢需求。粘液细胞也可能参与宿主免疫。