Wendt D E
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Biol Bull. 2000 Jun;198(3):346-56. doi: 10.2307/1542690.
The amount of energy available to larvae during swimming, location of a suitable recruitment site, and metamorphosis influences the length of time they can spend in the plankton. Energetic parameters such as swimming speed, oxygen consumption during swimming and metamorphosis, and elemental carbon and nitrogen content were measured for larvae of four species of bryozoans, Bugula neritina, B. simplex, B. stolonifera, and B. turrita. The larvae of these species are aplanktotrophic with a short free-swimming phase ranging from less than one hour to a maximum of about 36 hours. There is about a fivefold difference in larval volume among the four species, which scales linearly with elemental carbon content and, presumably, with the amount of endogenous reserves available for swimming and metamorphosis. Mean larval swimming speeds (in centimeters per second) were similar among species. Specific metabolic rate and larval size were inversely related. For larvae of a given species, respiration rates remained similar for swimming and metamorphosis; however, because metamorphosis lasts about twice as long as a maximal larval swimming phase, it was more energetically demanding. Larger larvae expended more energy to complete metamorphosis than did smaller larvae, but in terms of the percentage of larval energy reserves consumed, swimming and metamorphosis were more "expensive" for smaller larvae. A comparison of the energy expended during larval swimming calculated on the basis of oxygen consumption and on the basis of elemental carbon decrease suggests that larvae of Bugula spp. may not use significant amounts of dissolved organic material (DOM) to supplement their endogenous energy reserves.
幼虫在游泳期间可获得的能量、合适附着地点的位置以及变态过程会影响它们在浮游阶段所能停留的时间。我们对四种苔藓虫（丽苔虫、单苔虫、匐茎苔虫和塔苔虫）的幼虫测量了能量参数，如游泳速度、游泳和变态期间的耗氧量以及元素碳和氮含量。这些物种的幼虫是非浮游营养型的，自由游泳阶段较短，从不到一小时到最长约36小时不等。这四个物种的幼虫体积相差约五倍，与元素碳含量呈线性比例关系，大概也与可用于游泳和变态的内源性储备量相关。各物种间幼虫的平均游泳速度（厘米/秒）相似。特定代谢率与幼虫大小呈负相关。对于给定物种的幼虫，游泳和变态期间的呼吸速率保持相似；然而，由于变态持续时间约为幼虫最大游泳阶段的两倍，其能量需求更高。较大的幼虫完成变态比小幼虫消耗更多能量，但就消耗的幼虫能量储备百分比而言，游泳和变态对较小的幼虫来说更“昂贵”。基于耗氧量和基于元素碳减少量计算的幼虫游泳期间消耗能量的比较表明，丽苔虫属的幼虫可能不会利用大量溶解有机物质（DOM）来补充其内源性能量储备。
