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The Role of Pelagic Crags in the Grazing of Phytoplankton Off Baja California
Author(s) -
Longhurst Alan R.,
Lorenzen Carl J.,
Thomas William H.
Publication year - 1967
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1933100
Subject(s) - grazing , pelagic zone , phytoplankton , zooplankton , upwelling , grazing pressure , oceanography , diatom , ecology , bloom , environmental science , algal bloom , biology , geology , nutrient
The galathied crab Pleuronocodes planipes, which occurs in very dense and extensive pelagic concentrations to the west of Baja California, is capable of filter—feeding on natural diatom blooms. Its filtering mechanism is similar to that previously known in Porcellana. It is only in regions of coastal diatom blooms that Pleuroncodes feeds exclusively on Phytoplankton; elsewhere, it feeds on protista and zooplankters. A study of production and grazing in a coastal upwelling situation suggested that the observed zooplankton community would have incapable of sustaining more than about 10% of the apparent grazing rate, and calculations based on estimated grazing rates for Pleuroncodes suggested that the observed standing stock of this species could go far towards supplying the remainder of the apparent grazing pressure. Pelagic crabs may thus, at least in certain situations, play a dominant role in grazing down diatom blooms in the southern part of the California Current.