Fish predation after weakly synchronized larval release in a coastal upwelling system

Rasmuson, Leif K.; Morgan, Steven G.

doi:10.3354/meps10460

Cited by 4 publications

(8 citation statements)

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“…Potential lingering scent after the removal of predators in our flow-through tanks was not an issue because results were similar in predator and control treatments. Further, larval release during late ebb tide was also common during our field experiment as well as a companion study in natural populations (Rasmuson and Morgan, 2013). Finally, a previous study also concluded that behaviors of P. crassipes are not altered simply by holding them in the laboratory (Bovbjerg, 1960).…”

Section: Discussionmentioning

confidence: 67%

“…In a companion study, predation was indeed highest on newly released larvae of P. crassipes and other shore crabs when larval release peaked away from the safe period (intermediate amplitude ebb tides in twilight; Rasmuson and Morgan, 2013). However, predation was not as high as expected, because planktivorous fishes were not always present while females were releasing larvae.…”

Section: Discussionmentioning

confidence: 94%

“…The timing of larval release by shore crabs in cold nonupwelling regions of the world should be examined to determine whether weak synchrony also occurs there, especially in mixed tidal regimes that are more challenging to track than the regular phasing of environmental cycles in semidiurnal tidal regimes (Morgan, 1996a(Morgan, , 1996bMorgan and Anastasia, 2008;Morgan and Christy, 1994). We also provided the first evidence that predatory fishes do not alter the timing of larval release or other activities of ovigerous females, which spend much of their time in the safety of refuges, despite recent work demonstrating that planktivorous fishes do consume P. crassipes larvae (Rasmuson and Morgan, 2013). Because peak release during the safe period already minimizes predation on larvae, females apparently cannot further increase survival of either adults or larvae by delaying release in response to passing predators.…”

Section: Discussionmentioning

confidence: 97%

“…The number of fishes in each of three predator treatments remained constant throughout the experiment: two juvenile S. marmoratus, five adult G. aculeatus and no predators. More G. aculeatus than S. marmoratus were placed in each tank, because the latter species is smaller and more prevalent (Rasmuson and Morgan, 2013). Three replicate aquaria (110 l) were used for each of the three treatments resulting in a total of nine tanks per trial.…”

Section: Affect Of Predators On the Timing Of Larval Releasementioning

confidence: 99%

“…The predator on adults was the cabezon, Scorpaenichthys marmoratus (Ayers 1854), which feeds on P. crassipes and other benthic invertebrates and fishes (O'Connell, 1953). The planktivore was the three-spined stickleback, Gasterosteus aculeatus (Linnaeus 1758), which preys on P. crassipes larvae and other zooplankton (Rasmuson and Morgan, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Weakly synchronized larval release maintained in the presence of predatory fishes

Rasmuson¹,

Couture²,

Morgan³

2014

Journal of Experimental Marine Biology and Ecology

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a b s t r a c t a r t i c l e i n f oMany marine species minimize predation during hatching or spawning by releasing larvae or gametes synchronously during nocturnal spring ebb tides. Propagules are then rapidly transported away from high densities of predatory fishes into deeper waters under the cover of darkness. Females also suspend foraging in the presence of predators, but it is unknown whether they are able to delay releasing larvae. In a previous study, we found that larval release is only weakly synchronized to the safe period in a cold upwelling region, although the study was conducted on outdoor seawater tables in the absence of tides that reinforce endogenous rhythms. In this study, we experimentally determined whether larval release 1) is better synchronized in the field and 2) delayed in the presence of predatory fishes. Larval release was weakly synchronized to tidal amplitude, tidal and diel cycles, occurring from late flood to late ebb tide on both intermediate and spring tides during twilight as well as darkness. Weak synchrony likely arises because cold temperatures extend incubation of externally brooded embryos, increasing exposure to environmental variation. Larval release was not delayed in the presence of predatory fishes; nor was refuge use or other behaviors of females altered by fishes. Behaviors were not affected by predators presumably because larvae are already being released near the safe period from refuges. Our results likely apply to other cold regions of the world, but it remains to be determined whether predators alter the activities of nonovigerous female and male shore crabs, which may not spend as much time in refuges as ovigerous females, potentially resulting in cascading effects on communities.

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Section: Discussionmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 97%

Section: Affect Of Predators On the Timing Of Larval Releasementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Weakly synchronized larval release maintained in the presence of predatory fishes

Rasmuson¹,

Couture²,

Morgan³

2014

Journal of Experimental Marine Biology and Ecology

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Predation and Competition

Bashevkin¹,

Morgan²

2020

Developmental Biology and Larval Ecology

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Crustacean larvae are subject to predation by a diverse assemblage of invertebrate and vertebrate predators. These predators can find larval prey through visual, tactile, or chemical means and then capture larvae with feeding currents, grasping appendages, suction, or filtering sieves. In response to this predation, crustacean larvae have evolved extensive morphological defenses such as long spines and hard chitinous carapaces. They also exhibit sophisticated behaviors, including extensive vertical and horizontal migrations to avoid encountering predators, rapid darting to evade attacks by nearby predators, and strong swimming to escape after an attack by a predator. Chemical defenses have not yet been documented in crustacean larvae. Interspecific differences in defensive capabilities can be profound, including crab zoeae with spines zero to seven times their body length, and copepod nauplii with dichotomous swimming behaviors that trade off detectability by predators with escape ability. Our review of the literature on predator gut contents and lab feeding experiments found that crustacean larvae are consumed by a vast diversity of predators of all feeding types. These include gray whales, fishes, ascidians, bivalves, octopus larvae, cnidarians, insects, and numerous other crustaceans. Crustacean larvae are important components of many predators’ diets, and the primary food for others, including larvae of commercially important species such as cod. Future research on chemical defenses and phenotypic plasticity are needed to fill gaps in our knowledge of crustacean larval defenses. The predatory threats faced by crustacean larvae and their defensive adaptations have important implications for our understanding of the evolution of larval forms in Crustacea and the factors determining crustacean abundance and distribution.

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Planktonic predation risk: effects of diel state, season and prey life history stage

Kerr

Cornejo

Guichard

et al. 2015

Journal of Plankton Research

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Predation is considered an important source of mortality for plankton, but documenting variation in planktonic predation, particularly across interacting environmental cycles, remains logistically difficult, thus our understanding remains limited. To test for the combined effects of prey life history stage, diel or light level phase (including crepuscular periods) and seasonal upwelling on the risk of predation, we deployed tethered adult and larval brine shrimp Artemia franciscana using dock-based plankton tethering units (PTUs). Risk was higher overall during upwelling, but life history stage also interacted with season. There was no seasonal difference in risk for adults. Larvae were at significantly lower risk of predation during non-upwelling than during upwelling. Larvae were also at lower risk during nonupwelling than were adults during either season. During upwelling, there was no significant difference in risk between the two prey categories. With respect to the diel cycle, dusk was safer than daytime. For larvae, the diel pattern in risk remained consistent across seasons while risk for adults at night was slightly lower during upwelling than during nonupwelling. Variation in planktonic predation risk across diel and seasonal cycles differs for different life history stages and thus, generalizations fail to capture the complexity of interactions between factors.

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Fish predation after weakly synchronized larval release in a coastal upwelling system

Cited by 4 publications

References 58 publications

Weakly synchronized larval release maintained in the presence of predatory fishes

Weakly synchronized larval release maintained in the presence of predatory fishes

Predation and Competition

Planktonic predation risk: effects of diel state, season and prey life history stage

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