Production and Respiration in Animal Populations

Humphreys, W. F.

doi:10.2307/4171

Cited by 283 publications

(120 citation statements)

References 77 publications

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“…Small differences in food-chain length between our stream and lagoon food webs may therefore be expected. Even small differences in food-chain length may result in large differences in the amount of energy required to support upper trophic-level consumers due to low energetic assimilation efficiency of trophic interactions (10% on average; Humphreys, 1979). Small differences in trophic position can therefore have important natural resource management and conservation implications, such as for fisheries sustainability (e.g.…”

Section: Centropomus Undecimalis Diapterus Auratus Eugerres Plumiermentioning

confidence: 99%

Aquatic food webs in mangrove and seagrass habitats of Centla Wetland, a Biosphere Reserve in Southeastern Mexico

et al. 2010

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Mangrove and seagrass habitats are important components of tropical coastal zones worldwide, and are conspicuous habitats of Centla Wetland Biosphere Reserve (CWBR) in Tabasco, Mexico. In this study, we examine food webs in mangrove-and seagrass-dominated habitats of CWBR using stable isotope ratios of carbon and nitrogen. Our objective was to identify the importance of carbon derived from mangroves and seagrasses to secondary production of aquatic consumers in this poorly studied conservation area. Carbon and nitrogen isotope ratios of basal sources and aquatic consumers indicated that the species-rich food webs of both habitats are dependent on riparian production sources. The abundant Red mangrove Rhizophora mangle appears to be a primary source of carbon for the mangrove creek food web. Even though dense seagrass beds were ubiquitous, most consumers in the lagoon food web appeared to rely on carbon derived from riparian vegetation (e.g. Phragmites australis). The introduced Amazon sailfin catfish Pterygoplichthys pardalis had isotope signatures overlapping with native species (including high-value fisheries species), suggesting potential competition for resources. Future research should examine the role played by terrestrial insects in linking riparian and aquatic food webs, and impacts of the expanding P. pardalis population on ecosystem function and fisheries in CWBR. Our findings can be used as a baseline to reinforce the conservation and management of this important reserve in the face of diverse external and internal human impacts.Manguezais e pradarias de gramíneas são importantes componentes das zonas costeiras tropicais em todo o mundo, sendo habitats comuns nos "Pântanos de Centla", uma Reserva da Biosfera localizada em Tabasco, México. Nesse trabalho, são investigadas as teias alimentares de habitats dominados por manguezais e pradarias de gramíneas, através de isótopos estáveis de carbono e nitrogênio, tendo como objetivo identificar a importância do carbono derivado desses produtores para a produção aquática secundária nessa unidade de conservação tão pouco estudada. As razões isotópicas de carbono e nitrogênio das fontes basais e dos consumidores aquáticos indicam que as teias alimentares, ricas em espécies, de ambos os habitats, são dependentes da produção ripária. O abundante mangue-vermelho Rhizophora mangle parece ser a fonte primária de carbono no habitat dominado por manguezais. Em contraste, muito embora as pradarias de gramíneas sejam conspícuas no ambiente lagunar estudado, muitos dos consumidores da teia alimentar nessa região parecem depender do carbono oriundo da vegetação ripária (e.g. Phragmites australis). A espécie de bagre exótica Pterygoplichthys pardalis possui assinaturas isotópicas que se sobrepõem a das espécies nativas (incluindo algumas de elevado valor comercial na pesca), sugerindo competição potencial por recursos. Novas investigações deveriam avaliar o papel dos insetos terrestres como elo de conexão entre as teias alimentares da mata ripária e do ambiente aquático, b...

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Section: Centropomus Undecimalis Diapterus Auratus Eugerres Plumiermentioning

confidence: 99%

Aquatic food webs in mangrove and seagrass habitats of Centla Wetland, a Biosphere Reserve in Southeastern Mexico

et al. 2010

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“…Assuming the summer rates measured 21 to be valid for about 100 days year and the relation between production and respiration to be P¯0.87 ? R (Humphreys, 1979), annual production of Barents Sea m year ) and the 500-700 m depth stratum (2.1 g C m year ). Unfortunately, Piepenburg et al (1995) do not provide biomass data for the total macro / megafauna, and hence we cannot decide whether the Barents Sea community shows lower biomass or lower P/B ratio than the Weddell and Lazarev Sea community.…”

mentioning

confidence: 99%

High Antarctic macrobenthic community production

Brey

Gerdes

1998

Journal of Experimental Marine Biology and Ecology

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Production and productivity (P/B ratio) of the high Antarctic Weddell Sea and Lazarev Sea macrozoobenthos are estimated by an empirical multiple non-linear model (artificial neural network) based on biomass data and other biotic and abiotic parameters. Average community (1500-4300 m). Community P/B ratio increases with depth from 0.18 year to 0.55 year . Taking into account the effects of water depth on production and of temperature on P/B ratio, Antarctic communities show no evidence of unique characteristics with respect to overall energy flow.

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“…Nevertheless, the model estimates of respiration fell within acceptable ranges as described in the literature for taxonomic groups. P/R ratios of fish groups ranged between 0.117 and 0.181, which is slightly higher than the mean value of 0.11 presented by Humphreys (1979). Benthic invertebrate P/R ratios had a wide range (0.193-0.948), but the average value of 0.475 is also very close to mean values of 0.482 and 0.439 for aquatic invertebrates as described by Humphreys (1979) and Schwinghamer et al (1986), respectively.…”

Section: Trophic Modelmentioning

confidence: 53%

“…P/R ratios of fish groups ranged between 0.117 and 0.181, which is slightly higher than the mean value of 0.11 presented by Humphreys (1979). Benthic invertebrate P/R ratios had a wide range (0.193-0.948), but the average value of 0.475 is also very close to mean values of 0.482 and 0.439 for aquatic invertebrates as described by Humphreys (1979) and Schwinghamer et al (1986), respectively. All but one (Scallops-0.838) of our R/A estimates for benthic invertebrates fell within the expected range of 0.5-0.75 given by Mann (1982).…”

Section: Trophic Modelmentioning

confidence: 53%

Trophic and environmental drivers of the Sechura Bay Ecosystem (Peru) over an ENSO cycle

et al. 2007

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Interannual environmental variability in Peru is dominated by the El Niño Southern Oscillation (ENSO). The most dramatic changes are associated with the warm El Niño (EN) phase (opposite the cold La Niña phase), which disrupts the normal coastal upwelling and affects the dynamics of many coastal marine and terrestrial resources. This study presents a trophic model for Sechura Bay, located at the northern extension of the Peruvian upwelling system, where ENSO-induced environmental variability is most extreme. Using an initial steady-state model for the year 1996, we explore the dynamics of the ecosystem through the year 2003 (including the strong EN of 1997/98 and the weaker EN of 2002/03). Based on support from literature, we force biomass of several non-trophicallymediated 'drivers' (e.g. Scallops, Benthic detritivores, Octopus, and Littoral fish) to observe whether the fit between historical and simulated changes (by the trophic model) is improved. The results indicate that the Sechura Bay Ecosystem is a relatively inefficient system from a community energetics point of view, likely due to the periodic perturbations of ENSO. A combination of high system productivity and low trophic level target species of invertebrates (i.e. scallops) and fish (i.e. anchoveta) results in high catches and an efficient fishery. The importance of environmental drivers is suggested, given the relatively small improvements in the fit of the simulation with the addition of trophic drivers on remaining functional groups' dynamics. An additional multivariate regression model is presented for the scallop Argopecten purpuratus, which demonstrates a significant correlation between both spawning stock size and riverine discharge-mediated mortality on catch levels. These results are discussed in the context of the appropriateness of trophodynamic modeling in relatively open systems, and how management strategies may be focused given the highly environmentally influenced marine resources of the region.

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Production and Respiration in Animal Populations

Cited by 283 publications

References 77 publications

Aquatic food webs in mangrove and seagrass habitats of Centla Wetland, a Biosphere Reserve in Southeastern Mexico

Aquatic food webs in mangrove and seagrass habitats of Centla Wetland, a Biosphere Reserve in Southeastern Mexico

High Antarctic macrobenthic community production

Trophic and environmental drivers of the Sechura Bay Ecosystem (Peru) over an ENSO cycle

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