Size structure, sex ratio, and breeding season in two intertidal grapsid crab species from Mar Chiquita Lagoon, Argentina
Size structure, sex ratio, and breeding season in two intertidal grapsid crab species from Mar Chiquita Lagoon, Argentina
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发表时间：
1996
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通讯作者：
E. Spivak;K. Anger;Claudia C. Bas;T. Luppi;D. Ismael
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作者：
E. Spivak;K. Anger;Claudia C. Bas;T. Luppi;D. Ismael
在阿根廷的一个咸水沿海泻湖 Mar Chiquita 研究了两种草蟹的生活史模式。 Chasmagnathus capsulata 是一种生活在潮间带上部的穴居蟹，而 Cyrtograpsus angulatus 主要生活在潮间带下部和潮下带。颗粒 C. capsulata 在春季、夏季和秋季的大部分时间都很活跃（即觅食和繁殖），但在冬季大部分时间都隐藏在洞穴内。在男性和女性的体型频率分布中分别发现了两个主要体型组。由于该物种建造了复杂且相当稳定的洞穴，因此我们发现了相当均匀的空间分布和稳定的性别比例，仅与 1:1 的比例存在微弱的局部偏差。角鳅是一种流动性很强的物种，性别比例在时间和空间上变化很大，表明雄性和雌性局部迁徙的强度或方向存在差异。该物种在不同采样点的成体体型结构相似，雄性的体型频率分布显示出三个主要体型组，而雌性则只有一到两个体型组。在深秋，该物种的大多数个体离开潮间带，并在冬季停留在更深的水中。这两个物种都表现出明显的季节性繁殖活动模式，在夏初发现产卵雌性的最大比例，并且两者似乎都会在夏末之前产下几个卵窝。 C. angulatus 的繁殖季节（9 月至 5 月；冬季也发现了一些产卵雌性）比 C. 管理颗粒（10 月至 3 月）更长。在潮间带，观察到一小部分 C. angulatus 在胚胎晚期携带卵。这表明该物种的产卵雌性可能会迁移到潮下层，在更深的水中释放幼虫。
Life history patterns of two grapsid crab species were studied in Mar Chiquita, a brackish coastal lagoon in Argentina. Chasmagnathus granulata is a burrowing crab living in the upper intertidal, whereas Cyrtograpsus angulatus lives predominantly in the lower intertidal and subtidal. C. granulata is active (i.e. foraging and reproducing) during spring, summer and most of autumn, but remains mostly hidden inside its burrows during winter. Two dominant size groups each were found in the size-frequency distributions of males and females. Since this species builds elaborated and rather stable burrows, we found a rather uniform spatial distribution and a stable sex ratio, with only weak local deviations from a 1:1 ratio. In C. angulatus, which is a very mobile species, the sex ratio varied greatly in time and space, indicating local migrations with differential intensities or directions in males and females. Adult size structure in this species was similar at different sampling sites, with size frequency distribution of males revealing three dominant size groups, but that of females only one or two. In late autumn, most individuals of this species leave the intertidal zone and stay during winter in deeper water. Both species show a pronounced seasonal reproductive activity pattern, with a maximum percentage of ovigerous females found in the beginning of summer, and both appear to produce several subsequent egg clutches until late summer. The reproductive season is longer in C. angulatus (September-May; a few ovigerous females were found also in winter) than in C. granulata (October-March). In the intertidal, a low percentage of C. angulatus was observed to carry eggs in late embryonic stages. This suggests that ovigerous females of this species may migrate to the subtidal to release their larvae in deeper water.