T. Ignoffo - Academia.edu (original) (raw)
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California Polytechnic State University at San Luis Obispo
Ashoka Trust for Research in Ecology and the Environment (ATREE)
Maulana Azad National Institute of Technology
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Papers by T. Ignoffo
Limnology and Oceanography, 2013
In most aquatic ecosystems, copepod nauplii outnumber all other mesozooplankton. Although thousan... more In most aquatic ecosystems, copepod nauplii outnumber all other mesozooplankton. Although thousands of studies have examined feeding by later life history stages, the feeding habits of nauplii are poorly known. We offered conspecific adult and naupliar stages of the current-feeding calanoid copepod Pseudodiaptomus marinus and the ambush-feeding cyclopoid copepod Oithona davisae 14 species of phytoplankton from various functional and taxonomic groups that spanned a wide size range. Using a novel epifluorescence microscopy method, we calculated an index of gut pigment for copepods fed each phytoplankton species. We also measured adult and naupliar feeding rates on three species of phytoplankton: the cryptomonad Rhodomonas salina, the prasinophyte Tetraselmis suecica, and the diatom Thalassiosira pseudonana, by an improved gut fluorescence method using a microplate reader. Despite their smaller size, weaker swimming and sensory capabilities, and rudimentary feeding apparatus, nauplii fed on a large range of cell sizes and were capable of consuming many of the same phytoplankton as adults.
Journal of Plankton Research, 2014
We determined reproductive and growth rates of three common copepods in the low-salinity zone of ... more We determined reproductive and growth rates of three common copepods in the low-salinity zone of the San Francisco Estuary during spring -summer of 2006 and 2007. Rates were low, particularly during summer. The egg production rate of Eurytemora affinis in spring averaged 3 eggs female 21 day 21 or 0.04 day 21 , while that of Pseudodiaptomus forbesi in summer averaged 1 egg female 21 day 21 or 0.02 day 21 . Specific growth rates of copepodites were moderate for E. affinis in spring (0.23 and 0.15 day 21 for early and late stages, respectively) and low for P. forbesi in summer (0.15 and 0.03 day 21 , respectively). Growth and egg production rates of both species were generally lower than rates predicted from temperature for well-fed copepods, suggesting chronic food limitation. Previously published estimates for the small cyclopoid Limnoithona tetraspina were also low. None of the measures of growth of any species was related to phytoplankton biomass, primary production or abundance of the species, nor did they differ between the 2 years despite large differences in hydrology. To understand patterns of abundance will require investigation of differential mortality rates.
Limnology and Oceanography, 2013
In most aquatic ecosystems, copepod nauplii outnumber all other mesozooplankton. Although thousan... more In most aquatic ecosystems, copepod nauplii outnumber all other mesozooplankton. Although thousands of studies have examined feeding by later life history stages, the feeding habits of nauplii are poorly known. We offered conspecific adult and naupliar stages of the current-feeding calanoid copepod Pseudodiaptomus marinus and the ambush-feeding cyclopoid copepod Oithona davisae 14 species of phytoplankton from various functional and taxonomic groups that spanned a wide size range. Using a novel epifluorescence microscopy method, we calculated an index of gut pigment for copepods fed each phytoplankton species. We also measured adult and naupliar feeding rates on three species of phytoplankton: the cryptomonad Rhodomonas salina, the prasinophyte Tetraselmis suecica, and the diatom Thalassiosira pseudonana, by an improved gut fluorescence method using a microplate reader. Despite their smaller size, weaker swimming and sensory capabilities, and rudimentary feeding apparatus, nauplii fed on a large range of cell sizes and were capable of consuming many of the same phytoplankton as adults.
Journal of Plankton Research, 2014
We determined reproductive and growth rates of three common copepods in the low-salinity zone of ... more We determined reproductive and growth rates of three common copepods in the low-salinity zone of the San Francisco Estuary during spring -summer of 2006 and 2007. Rates were low, particularly during summer. The egg production rate of Eurytemora affinis in spring averaged 3 eggs female 21 day 21 or 0.04 day 21 , while that of Pseudodiaptomus forbesi in summer averaged 1 egg female 21 day 21 or 0.02 day 21 . Specific growth rates of copepodites were moderate for E. affinis in spring (0.23 and 0.15 day 21 for early and late stages, respectively) and low for P. forbesi in summer (0.15 and 0.03 day 21 , respectively). Growth and egg production rates of both species were generally lower than rates predicted from temperature for well-fed copepods, suggesting chronic food limitation. Previously published estimates for the small cyclopoid Limnoithona tetraspina were also low. None of the measures of growth of any species was related to phytoplankton biomass, primary production or abundance of the species, nor did they differ between the 2 years despite large differences in hydrology. To understand patterns of abundance will require investigation of differential mortality rates.