Carbon productivity and flux in the marine ecosystems of the Galapagos Marine Reserve based on cetacean abundances and trophic indices
ABSTRACT The role of cetaceans in marine ecosystems and food webs is scarcely known in the southeastern Pacific. Estimates of secondary and tertiary (carbon) production and daily food intake were deduced for five species of representative cetaceans for different marine habitats of the Galapagos by u...
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| Lenguaje: | English |
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Universidad de Valparaíso. Facultad de Ciencias del Mar
2009
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| Acceso en línea: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-19572009000100010 |
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| Sumario: | ABSTRACT The role of cetaceans in marine ecosystems and food webs is scarcely known in the southeastern Pacific. Estimates of secondary and tertiary (carbon) production and daily food intake were deduced for five species of representative cetaceans for different marine habitats of the Galapagos by using associated calculations of annual primary production and carbon flux, as well as estimations of relative abundance, biomass, absolute density and trophic levels (TL) reported elsewhere. Under these premises, sperm (Physeter macrocephalus) and carnivore-generalist killer whales (Orcinus orca) for open ocean (i.e. no upwelling regions) had the lowest values of tertiary production at the top predator level (0.01-1.01 gC m-2 yr-1), while Bryde's (Balaenoptera edeni) and blue (B. musculus) whales from upwelling zone located at southwest Galapagos Island yielded the highest cetacean production (13.7 and 35.4 gC m-2 yr-1, respectively). Significant positive correlations at a 15% of efficiency transfer were found between the estimated annual primary production and tertiary production of baleen whales, and between annual primary production and tertiary production of toothed cetaceans. When both groups of cetaceans were combined a no significant correlation was observed between cetacean production and annual primary productivity. This outcome was influenced by their different trophic positions in the food chain and different scenarios values of annual primary productivity of the marine ecosystems selected. More research is needed to determine abundance, prey selection, feeding rates, and fecal matter sinking rates from marine mammals in Galapagos waters, as well as their function in the vertical carbon flux. |
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