Unpalatability of a colonial rotifer, Sinantherina socialis to small zooplanktivorous fishes
Unpalatability of a colonial rotifer, Sinantherina socialis to small zooplanktivorous fishes
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群居轮虫、社会主义轮虫对小型浮游动物食性鱼类的不适口性
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
R. Wallace
中科院分区：
文献类型：
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作者：
A. Felix;M. Stevens;R. Wallace
Sinantherina socialis（轮虫门）的群体形成明显的群体，这应该使它们非常容易受到能够捕获小型活猎物（长度<3毫米）的鱼类的攻击。为了验证这一假设，我们提供了轮虫殖民地作为猎物的14种小口，掠食性鱼类，交替与小枝角类。大多数轮虫（71-100%），但少数枝角类（0-14%）被拒绝后捕获。鱼类对轮虫的摄食行为遵循一致的模式：定位、接近、攻击、反复张嘴和拒绝（吐出）。除了少数个体的损失，被多次拒绝的轮虫群体仍然完好无损。这是第一个轮虫对食动物性鱼类不适口的证据。附加关键词：鱼类摄食，花尾轮虫科，单角目，捕食，捕食性防御，轮虫，难食性，食虫性轮虫（约100-1000| jm）成为各种触觉无脊椎动物捕食者的猎物，如其他轮虫、昆虫幼虫以及微型和大型甲壳类动物（威廉姆森1983; Stemberger &吉尔伯特1987）。它们也是海水和淡水鱼幼体的极好食物来源（Newrkla &邓肯1984; Lubbard 1987; Lubbard等人1989）。即使有替代猎物，幼鱼也可能大量捕食轮虫（朗道等人，1988年）（休伊特和乔治，1987年; Zale和Gregory，1990年）。因此，轮虫被夹在触觉和视觉捕食的两个磨盘之间;除了保持较小的体型，保持对许多触觉捕食者的敏感性外，没有任何地方可以躲避食兽鱼类。轮虫对触觉捕食者的一种防御似乎是群体的形成，至少在那些产生凝胶状基质的物种中（例如，Conochilidae REMANE 1933）。对于这些种类而言，胶状物提供了一个避难所，轮虫在受到攻击时可以缩入其中（吉尔伯特，1980）。然而，轮虫中的菌落形成使有效大小增加了几倍，使菌落的大小范围在0.8至4 mm之间，这是小型食虫鱼类或其幼虫可以消耗的（Siefert 1972; Crecco & Blake 1983;奥布莱恩& Evans 1991）。因此，这似乎是合理的，殖民轮虫应该存在于栖息地的触觉捕食者比视觉捕食者的捕食更激烈。当然，群体的形成可能会产生其他后果，比如增加了信件的收件人。水流过一组密集个体的效率，这些个体从事悬浮喂养（参见Wallace 1987的综述）。在8个有集群种的属中，Sinantherina BORY DE ST. VINCENT 1826属（单角目，Flosculariidae）特别有趣，因为Sinantherinids不具有该科特有的凝胶基质，许多种类形成的集群如此之大和明显，以至于它们很容易从水面上看到。例如，两种sinantherinids产生浮游幼鱼，成年群体是固着在水生植物上：S。ariprepes EDMONDSON 1939（Edmondson 1940），S. socialis（LINNAEUS 1758）（Surface 1906; Wallace 1987）.第三种sinantherinid是全栖于浅水沃茨，S. semibullata（THORPE 1889）（Canella 1952; Gunter & Knight 1978）.由于这些特征，人们可能会认为sinantherinids将非常容易受到鱼类捕食，但他们经常出现在栖息地与小型，捕食性鱼类（R。华莱士，未公开。obs.）。这些群体轮虫如何避免被鱼类灭绝？Kerfoot和他的同事已经证明，许多明显的水生节肢动物（昆虫和hydrocarinids）具有化学防御（例如，类固醇）对鱼类捕食的影响（Kerfoot et al. 1980; Kerfoot 1982; Scrimshaw & Kerfoot 1987）。从这项工作中推断，我们中的一个（华莱士1987）建议，殖民地的S。群居鱼可能具有化学防御能力，使它们对食虫鱼类来说不好吃。在这里，我们描述了一个更简单的假设的测试：此内容从157.55.39.153下载星期一，19九月2016 04：42：00 UTC所有使用受http://about.jstor.org/terms费利克斯，史蒂文斯，和华莱士，S的殖民地。群居鱼是掠食性鱼类所不喜欢的，其捕食率低于其它小型活猎物。
Colonies of Sinantherina socialis (phylum Rotifera) form conspicuous masses that should make them extremely vulnerable to fishes capable of ingesting small live prey (<3 mm in length). To test this hypothesis we offered rotifer colonies as prey to 14 species of smallmouthed, predatory fishes, alternating with small cladocerans. Most rotifer colonies (71-100%), but few cladocerans (0-14%) were rejected after capture. Fish feeding behavior on rotifers followed a consistent pattern: locate, approach, attack, mouth repeatedly, and reject (spit out). Except for loss of a few individuals, rotifer colonies that had been repeatedly rejected remained undamaged. This is the first evidence for unpalatability of rotifers to zooplanktivorous fishes. Additional key words: fish feeding, Flosculariidae, Monogononta, predation, predatory defense, Rotifera, unpalatability, zooplanktivory Rotifers (about 100-1000 |jm) fall prey to a variety of tactile invertebrate predators such as other rotifers, insect larvae, and microand macrocrustaceans (Williamson 1983; Stemberger & Gilbert 1987). They also are an excellent food source for marine and freshwater fish larvae (Newrkla & Duncan 1984; Lubzens 1987; Lubzens et al. 1989). Larval fishes may feed extensively on rotifers (Landau et al. 1988), even when alternate prey are available (Hewitt & George 1987; Zale & Gregory 1990). Thus, rotifers are caught between the two millstones of tactile and visual predation; there is no refuge from zooplanktivorous fishes other than preserving a small body size, which maintains susceptibility to many tactile predators. One defense against tactile predators used by rotifers appears to be the formation of colonies, at least in those species that produce a gelatinous matrix (e.g., Conochilidae REMANE 1933). For those species the jelly mass provides a refuge into which the rotifers may retract when attacked (Gilbert 1980). However, colony formation in rotifers increases effective size by several fold, placing the colonies within a size range consumable by small zooplanktivorous fishes or their larvae: 0.8 to 4 mm (Siefert 1972; Crecco & Blake 1983; O'Brien & Evans 1991). Therefore, it seems plausible that colonial rotifers should be present in habitats where predation by tactile predators is more intense than by visual predators. Of course, colony formation may have other consequences, such as increasing the a To whom correspondence should be addressed. efficiency of water flow over a group of closely spaced individuals engaged in suspension feeding (see Wallace 1987 for a review). Of 8 rotifer genera with colonial species, the genus Sinantherina BORY DE ST. VINCENT 1826 (Monogononta, Flosculariidae) is particularly interesting because sinantherinids do not possess the gelatinous matrix that is characteristic of the family and many species form colonies so large and conspicuous that they are easily seen from above the water surface. For example, two sinantherinids produce pelagic juveniles with adult colonies that are sessile on aquatic plants: S. ariprepes EDMONDSON 1939 (Edmondson 1940), S. socialis (LINNAEUS 1758) (Surface 1906; Wallace 1987). A third sinantherinid is holoplanktonic in shallow waters, S. semibullata (THORPE 1889) (Canella 1952; Gunter & Knight 1978). As a consequence of these features, one might expect that sinantherinids would be extraordinarily vulnerable to fish predation, yet they are often present in habitats with small, predatory fishes (R. Wallace, unpubl. obs.). How do these colonial rotifers avoid extirpation by fishes? Kerfoot and his co-workers have demonstrated that many conspicuous aquatic arthropods (insects and hydracarinids) have chemical defenses (e.g., steroids) against predation by fishes (Kerfoot et al. 1980; Kerfoot 1982; Scrimshaw & Kerfoot 1987). Extrapolating from that work, one of us (Wallace 1987) suggested that colonies of S. socialis might possess chemical defenses rendering them unpalatable to zooplanktivorous fishes. Here we describe a test of a simpler hypothesis: This content downloaded from 157.55.39.153 on Mon, 19 Sep 2016 04:42:00 UTC All use subject to http://about.jstor.org/terms Felix, Stevens, & Wallace that colonies of S. socialis are unpalatable to predatory fishes and will be preyed upon at lower rates than will other small live prey.