Diel vertical movement by mesograzers on seaweeds

Rogers, Cary N.; Williamson, Jane E.; Carson, David G.; Steinberg, Peter D.

doi:10.3354/meps166301

Cited by 23 publications

(25 citation statements)

References 23 publications

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“…Due to their diel movement on these algae (Rogers et al 1998), A. parvula were rarely visible on either host seaweed during the day compared to at night. This cryptic behaviour in combination with cryptic body colouration may reduce encounters with fishes, and suggests that visual predators are an important selective force (e.g.…”

Section: Predation By Fishesmentioning

confidence: 99%

“…Hay et al 1989), and this property could be an important component of host choice by this sea hare. Delisea pulchra and Laurencia obtusa have complex habits which A. parvula exploit as cover during daylight by moving into the enclosed basal parts (Rogers et al 1998). The performance of A. parvula varies greatly between these host algae, yet a poor-quality host like D. pulchra which is costly to consume may have compensatory benefits.…”

Section: Predation By Fishesmentioning

confidence: 99%

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Effects of algal diet on the performance and susceptibility to predation of the sea hare Aplysia parvula

Rogers¹,

Nys²,

Steinberg³

2002

Mar. Ecol. Prog. Ser.

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Although sea hares are well known for acquiring algal secondary metabolites from their diet, the effects of diet on fitness and the susceptibility of sea hares to predators are poorly understood. We examined the effects of diet on the performance of the sea hare Aplysia parvula, and measured predation by reef fishes on sea hares raised on different seaweeds. Diet-switching, body size, the presence of conspecifics, and the presence of epiphytes on dietary algae were also investigated experimentally. A. parvula were fed the chemically rich red algae Delisea pulchra or Laurencia obtusa in laboratory experiments, and consumption, growth, egg production, conversion efficiency, and survivorship were measured. Sea hares fed L. obtusa consumed more algae, grew faster, laid more eggs, and had higher survivorship compared to sea hares fed D. pulchra. Most other factors investigated -body size, the presence of conspecifics or epiphytes -were in general unimportant relative to the effects of diet. The disparity in fitness of A. parvula fed D. pulchra versus L. obtusa is primarily due to different levels of consumption of each seaweed, as conversion efficiencies were similar. Predation on sea hares raised on different diets and containing different types and levels of acquired secondary metabolites was measured in field experiments in which sea hares were exposed to mixed assemblages of reef fishes. A high proportion of both chemically rich (fed red algae) and chemically poor sea hares (fed the green alga Ulva sp.) were eaten by fishes (with predation rates of 25 to 55% over 1 to 2 h), although this sea hare was relatively unpalatable compared to squid tissue. Juvenile A. parvula were eaten at a significantly greater rate than adults. Sea hare ink did not deter some fishes, which consumed both de-inked and untreated sea hares. Predation by fishes was similar in adjacent habitats, but varied between sites, and was not restricted to A. parvula as reef fishes also ate juvenile A. dactylomela of equivalent size. The benefit A. parvula gain from acquiring algal secondary metabolites is unclear, as these compounds appear ineffective as defences against some fishes. A. parvula may sequester algal secondary metabolites as part of a broader defensive strategy that includes crypsis and escape movements.

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Section: Predation By Fishesmentioning

confidence: 99%

Section: Predation By Fishesmentioning

confidence: 99%

Effects of algal diet on the performance and susceptibility to predation of the sea hare Aplysia parvula

Rogers¹,

Nys²,

Steinberg³

2002

Mar. Ecol. Prog. Ser.

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“…Thus, activities of the mobile fauna such as feeding, reproduction and dispersal should be more concentrated in nocturnal periods (ROGERS et al, 1998;JØRGENSEN & CHRISTIE, 2003). However, few works evaluated this hypothesis, which was generally tested through observational studies.…”

Section: Discussionmentioning

confidence: 99%

“…However, few works evaluated this hypothesis, which was generally tested through observational studies. For example, ROGERS et al (1998) evaluated the activities of mesograzers during the day and at night, and found a higher proportion of sighted individuals at night. However, the effects of predators on prey behavior are generally complex, and indirect effects can be common.…”

Section: Discussionmentioning

confidence: 99%

“…For example, mobile epifauna can associate with substrates less susceptible to predators due to the presence of chemical defenses (HAY et al, 1987), or present activity patterns that differ from that shown by predators, mainly those which are visually oriented (ROGERS et al, 1998;LINKE et al, 2001). In this case, some studies found greater activity of macro invertebrates at night in periods of new moon, when compared with densities during the day or full moon nights, although variation among faunal groups has been found (TAYLOR, 1998;SÁNCHEZ-JEREZ et al, 1999;LINKE et al, 2001;JØRGENSEN & CHRISTIE, 2003).…”

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confidence: 93%

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Diel density variation of amphipods associated with Sargassum beds from two shores of Ubatuba, Southeastern, Brazil

Leite

Tanaka

Sudatti

et al. 2007

Iheringia, Sér. Zool.

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ABSTRACT. Densities of mobile epifaunal assemblages associated with macrophytes are very variable during the day and the activity of visually-oriented predators is thought to have an important influence on this pattern. Here we compared densities of amphipods associated with a common brown alga, Sargassum stenophyllum (Phaeophyceae), at sites contrasting in water turbidity. We expected that diel variation of amphipods would occur in a shore with clear waters (Perequê), whereas no variation was expected in a shore with turbid waters (Lamberto). Amphipod density varied during the day at both shores, with no indication of a larger variation at Perequê. Most species showed two density peaks, one at night and the other in the afternoon. These peaks occurred close the times of high tide, suggesting that tidal rhythms could influence more amphipod densities than the activity of predators. Thus, more studies are necessary to understand factors that influence short-term variation of epifaunal assemblages. KEYWORDS. Diel variation, amphipods, Sargassum.RESUMO. Variação ao longo do dia na densidade de anfípodos associados a bancos de Sargassum em duas praias de Ubatuba, SP, Brasil. As densidades da epifauna móvel associada a macrófitas variam muito ao longo do dia, sendo a atividade de predadores visualmente orientados um dos principais fatores apontados para explicar este padrão. Neste estudo, comparamos as densidades de anfípodos associados a uma alga parda comum, Sargassum stenophyllum (Phaeophyceae), em praias contrastando em turbidez da água. Era esperada a ocorrência de variação ao longo do dia numa praia com águas claras (Perequê) e nenhuma variação na praia com águas turvas (Lamberto). A densidade de anfípodos variou ao longo do dia em ambas as praias, sem indicação de maior variação em Perequê. A maioria das espécies apresentou dois picos de densidade: um à noite e outro à tarde. Estes ocorreram próximos aos períodos de maré alta, sugerindo que o ritmo de maré poderia influenciar mais as densidades de anfípodos que a atividade de predadores. Assim, mais estudos são necessários para se compreender os fatores que influenciam a variação de curto prazo das comunidades epifaunais. PALAVRAS-CHAVE.Variação temporal, anfípodos, Sargassum.

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Fitness benefits of size-dependent diet switching in a marine herbivore

Williamson

Steinberg

2012

Mar Biol

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Although diet is one of the most important parameters affecting the fitness of terrestrial and marine herbivores, host plant choice and subsequent fitness on that host are not always correlated. This study investigated the effect of diet on fitness of the sea urchin Holopneustes purpurascens, which show an ontogenetic change in host plant use subsequent to recruitment. To test whether fitness on host plant mirrored host plant choice, small and large individuals were collected from both hosts and fed either host plant (Ecklonia radiata or Delisea pulchra). Small urchins survived better than large individuals. Those fed E. radiata produced fewer test lesions, grew faster and were more fecund than those fed D. pulchra, irrespective of size. This pattern was enhanced when the host plant the urchin previously inhabited was assessed. Our results show that diet is driving the previously recorded ontogenetic change in host plant use associated with increasing size in H. purpurascens, where medium-sized individuals switch from D. pulchra to E. radiata.

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Diel vertical movement by mesograzers on seaweeds

Cited by 23 publications

References 23 publications

Effects of algal diet on the performance and susceptibility to predation of the sea hare Aplysia parvula

Effects of algal diet on the performance and susceptibility to predation of the sea hare Aplysia parvula

Diel density variation of amphipods associated with Sargassum beds from two shores of Ubatuba, Southeastern, Brazil

Fitness benefits of size-dependent diet switching in a marine herbivore

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