Cannibalism of newly metamorphosed juvenile sea stars
Cannibalism of newly metamorphosed juvenile sea stars
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新变态的幼年海星的同类相食行为
DOI：
10.1002/ecy.3352
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发表时间：
2021
期刊：
影响因子：
4.8
通讯作者：
Allen, Jonathan D.
中科院分区：
文献类型：
--
作者：
Brocco French, Karina Inge;Allen, Jonathan D.
两周内每天都对剩余的海星进行计数。自然密度处理中的死亡率百分比比孤立幼年的背景死亡率高四倍（图2B；双尾t检验P = 0.012）。考虑到我们对同类相食的观察可能是由于缺乏合适的替代食物来源，我们随后测试了幼年蓝贻贝（Mytilus edulis）的存在对幼年海星同类相食的影响。将幼年海星 (SS) 和幼年贻贝 (M) 以 1SS+ 1M、2SS+ 2M、10SS+ 10M 和 15SS+ 15M 的密度随机分配到 250 mL 烧杯中。连续 2 周，每天对每个烧杯中剩余的海星（圆盘直径 800–1,200 µm）和贻贝（壳长 400–800 µm）的数量进行计数。有或没有贻贝作为替代食物来源的福贝西贻贝幼鱼的死亡率再次与密度相关（双向方差分析，F3，42 = 12.478，P < 0.001），但不受贻贝存在的影响（双向方差分析，F1，42 = 0.009，P = 0.924；图 2C），即使贻贝也存在时消耗。密度和贻贝的存在之间也没有显着的相互作用（双向方差分析，F3，42 = 1.429，P = 0.248）。我们还通过在每个 20 个 250 毫升烧杯中测量和随机分配幼体成对，测试了大小对幼体同类相食的影响。连续两周每天计数每个烧杯中剩余海星的数量。比较了同类相食与非同类相食的幼年体盘直径的差异（图2D）。在同类相食的个体中，圆盘直径的差异显着更大（双尾 t 检验；P < 0.001），并且仅当同类相食个体与其受害者之间的圆盘直径差异至少 300 µm 时才能观察到。这些数据强烈表明，幼年同类相食在这个小行星物种中具有特定的体型大小。
Remaining sea stars were counted every day for 2 weeks. Percent mortality in the natural density treatment was fourfold higher than the background mortality of isolated juveniles (Fig. 2B; two-tailed t-test P= 0.012). Concerned that our observations of cannibalism may be due to the lack of a suitable alternate food source, we then tested the effects of the presence of juvenile blue mussels (Mytilus edulis) on juvenile sea star cannibalism. Juvenile sea stars (SS) and juvenile mussels (M) were randomly distributed into 250-mL beakers at densities of 1SS+ 1M, 2SS+ 2M, 10SS+ 10M and 15SS+ 15M. The number of remaining sea stars (800–1,200-µm disk diameter) and mussels (400–800-µm shell length) in each beaker was counted every day for 2 weeks. Percent mortality for A. forbesi juveniles with and without mussels as an alternative food source was again density dependent (two-way ANOVA, F3, 42= 12.478, P< 0.001), but unaffected by the presence of mussels (two-way ANOVA, F1, 42= 0.009, P= 0.924; Fig. 2C) even though mussels were also consumed when present. There was also no significant interaction between density and the presence of mussels (two-way ANOVA, F3, 42= 1.429, P= 0.248).We also tested the effects of size on juvenile cannibalism by measuring and randomly assigning juveniles into pairs in each of 20, 250-mL beakers. The number of remaining sea stars in each beaker was counted every day for 2 weeks. Differences in disk diameters were compared across cannibalistic vs. noncannibalistic juvenile pairs (Fig. 2D). The differences in disk diameter were significantly greater in the cannibalistic pairs (two-tailed t-test; P< 0.001) and was only observed when there was at least a 300-µm difference in disk diameter between the cannibalizing individual and its victim. These data strongly suggest that juvenile cannibalism is size-specific in this asteroid species.