Chemical composition of midwater fishes as a function of depth of occurrence off the Hawaiian Islands: Food availability as a selective factor?

Childress, James J.; Price, Michael H. H.; Favuzzi, J.A.; Cowles, David L.

doi:10.1007/bf01344292

Cited by 56 publications

(27 citation statements)

References 41 publications

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“…Diverse micro-nekton taxa can differ substantially in potential energy content (on a per gram basis). For example, lipid contents of myctophid fishes (the primary species component of our 'zooplanktivorous fishes' group) can be up to an order of magnitude greater than those of mature epipelagic fish and squid prey (Childress et al 1990, Van Pelt et al 1997. Thus, lower levels of consumption of high energy density prey items will contribute disproportionately more to overall energy flow and declines in these species are likely to inordinately impact the fitness of their predators.…”

Section: Discussionmentioning

confidence: 99%

Finding the way to the top: how the composition of oceanic mid-trophic micronekton groups determines apex predator biomass in the central North Pacific

Choy

Wabnitz²,

Weijerman³

et al. 2016

Mar. Ecol. Prog. Ser.

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We updated and expanded a model of the pelagic ecosystem for the area of the central North Pacific occupied by the Hawaii-based longline fishery. Specifically, results from the most recent diet studies were used to expand the representation of the lesser-known non-target fish species (e.g. lancetfish, opah, snake mackerel) and 9 mid-trophic micronekton functional groups. The model framework Ecopath with Ecosim was used to construct an ecosystem energy budget and to examine how changes in the various micronekton groups impact apex predator biomass. Model results indicate that while micronekton fishes represented approximately 54% of micronekton biomass, they accounted for only 28% of the micronekton production. By contrast, crustaceans represented 24% of the biomass and accounted for 44% of production. Simulated ecosystem changes resulting from changes to micronekton groups demonstrated that crustaceans and mollusks are the most important direct trophic pathways to the top of the food web. Other groups appear to comprise relatively inefficient pathways or 'trophic dead-ends' that are loosely coupled to the top of the food web (e.g. gelatinous animals), such that biomass declines in these functional groups resulted in increased biomass at the highest trophic levels by increasing energy flow through more efficient pathways. Overall, simulated declines in the micronekton groups resulted in small changes in biomass at the very top of the food web, suggesting that this ecosystem is relatively ecologically resilient with diverse food web pathways. However, further understanding of how sensitive micronekton are to changes in ocean chemistry and temperature resulting from climate change is needed to fully evaluate and predict potential ecosystem changes.

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Section: Discussionmentioning

confidence: 99%

Finding the way to the top: how the composition of oceanic mid-trophic micronekton groups determines apex predator biomass in the central North Pacific

Choy

Wabnitz²,

Weijerman³

et al. 2016

Mar. Ecol. Prog. Ser.

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“…The distinction between benthic and pelagic is important as similar declines are not evident, or are not as pronounced, in benthic species (figure 2a). These declines are mirrored by patterns of enzymatic activity (Childress & Somero 1979;Sullivan & Somero 1980;Gibbs & Somero 1990;Seibel et al 1998Janssens et al 2000;Seibel 2007; figure 4), buffering capacity (Castelini & Somero 1981;Dickson & Somero 1987;Seibel et al 1997) and protein content (Childress & Nygaard 1974;Bailey & Robison 1986;Childress et al 1990b;Drazen 2002b;Seibel et al 2004) in locomotory muscles.…”

Section: Rates Of Metabolism In Relation To Environmental Variablesmentioning

confidence: 98%

The rate of metabolism in marine animals: environmental constraints, ecological demands and energetic opportunities

Seibel

Drazen

2007

Phil. Trans. R. Soc. B

280

213

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The rates of metabolism in animals vary tremendously throughout the biosphere. The origins of this variation are a matter of active debate with some scientists highlighting the importance of anatomical or environmental constraints, while others emphasize the diversity of ecological roles that organisms play and the associated energy demands. Here, we analyse metabolic rates in diverse marine taxa, with special emphasis on patterns of metabolic rate across a depth gradient, in an effort to understand the extent and underlying causes of variation. The conclusion from this analysis is that low rates of metabolism, in the deep sea and elsewhere, do not result from resource (e.g. food or oxygen) limitation or from temperature or pressure constraint. While metabolic rates do decline strongly with depth in several important animal groups, for others metabolism in abyssal species proceeds as fast as in ecologically similar shallow-water species at equivalent temperatures. Rather, high metabolic demand follows strong selection for locomotory capacity among visual predators inhabiting well-lit oceanic waters. Relaxation of this selection where visual predation is limited provides an opportunity for reduced energy expenditure. Large-scale metabolic variation in the ocean results from interspecific differences in ecological energy demand.Keywords: metabolism; deep sea; scaling; oxygen consumption; locomotion; marine INTRODUCTIONThe rates of metabolic processes in animals vary tremendously throughout the biosphere (e.g. Bennett 1991; Seibel 2007). The origins and scope of this variation are a matter of active debate. Some emphasize geometric and environmental constraints or resource limitation as its source (e.g. Gillooly et al. 2001;Brown et al. 2004), while others emphasize the diversity of ecological roles that organisms play and the associated energy demands (Childress 1995;Suarez 1996;Reinhold 1999;Clarke 2004;Seibel 2007) as a primary driver of metabolic variation. With this in mind, the present paper addresses three seemingly simple questions: (i) what is the extent of variation in the rate of metabolism across diverse taxa and environments, (ii) what environmental and ecological demands act on organisms to drive selection for high metabolic capacity, and (iii) under what environmental circumstances might such selection be relaxed or capacity be constrained?These questions have been pursued vigorously for decades but the clarity of the debate has been diminished by the subtlety of differences in capacity between the taxa most thoroughly studied, that often

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“…The overall average number of nemerteans/tow, average number/tow for each cruise, and average number/volume water filtered over all depth intervals sampled, were consistently 8-13 times greater off California than off Hawaii. Waters off California are generally characterized as having higher primary productivity and greater macrozooplankton biomass than waters in the Central Pacific, including those off Hawaii (Childress et al, 1990). This higher productivity might account, at least in part, for the greater abundance of pelagic nemerteans off California.…”

Section: Discussionmentioning

confidence: 99%

Observations on depth distribution, diversity and abundance of pelagic nemerteans from the Pacific Ocean off California and Hawaii

Roe

Norenburg

1999

Deep Sea Research Part I: Oceanographic Research Papers

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Chemical composition of midwater fishes as a function of depth of occurrence off the Hawaiian Islands: Food availability as a selective factor?

Cited by 56 publications

References 41 publications

Finding the way to the top: how the composition of oceanic mid-trophic micronekton groups determines apex predator biomass in the central North Pacific

Finding the way to the top: how the composition of oceanic mid-trophic micronekton groups determines apex predator biomass in the central North Pacific

The rate of metabolism in marine animals: environmental constraints, ecological demands and energetic opportunities

Observations on depth distribution, diversity and abundance of pelagic nemerteans from the Pacific Ocean off California and Hawaii

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