Aldehyde suppression of copepod recruitment in blooms of a ubiquitous planktonic diatom

Abstract

The growth cycle in nutrient-rich, aquatic environments starts with a diatom bloom that ends in mass sinking of ungrazed cells and phytodetritus. The low grazing pressure on these blooms has been attributed to the inability of overwintering copepod populations to track them temporally. We tested an alternative explanation: that dominant diatom species impair the reproductive success of their grazers. We compared larval development of a common overwintering copepod fed on a ubiquitous, early-blooming diatom species with its development when fed on a typical post-bloom dinoflagellate. Development was arrested in all larvae in which both mothers and their larvae were fed the diatom diet. Mortality remained high even if larvae were switched to the dinoflagellate diet. Aldehydes, cleaved from a fatty acid precursor by enzymes activated within seconds after crushing of the cell, elicit the teratogenic effect. This insidious mechanism, which does not deter the herbivore from feeding but impairs its recruitment, will restrain the cohort size of the next generation of early-rising overwinterers. Such a transgenerational plant-herbivore interaction could explain the recurringly inefficient use of a predictable, potentially valuable food resource--the spring diatom bloom--by marine zooplankton.

A Multifunctional Lipoxygenase with Fatty Acid Hydroperoxide Cleaving Activity from the Moss Physcomitrella patens

“…This suggests that only one single enzyme is required for the formation of several oxylipins found in wounded P. patens tissue. A comparable fast formation of ␣,␤,␥,␦-unsaturated aldehydes has also been observed in previous investigations of the fatty acid metabolism of wounded diatoms where these metabolites act as chemical defense molecules (32). After tissue disruption a rapid onset of aldehyde production occurs in wounded diatoms and stationary levels of these metabolites are present within the first minutes after cell disruption (25).…”

Apoptosis-Inducing Galactolipids from a Cultured Marine Diatom, Phaeodactylum tricornutum

“…Chloroplast-derived glycolipids and membrane-bound phospholipids have been shown to be the main substrates for the biosynthetic pathway that produces antiproliferative polyunsaturated aldehydes 23,31 in wounded and nutrient-starved cells of marine diatoms. [32][33][34] It is also known that fatty acid hydroperoxides display teratogenic and proapoptotic properties. 35 It is conceivable that an enzymatic reaction (lipoxygenase/O 2 ) of the two side chains of compound 1 would produce hydroperoxidecontaining fatty acids, which, in turn, by enzymatic breakdown (lyase) would produce polyunsaturated aldehydes (decatrienal and octadienal).…”

Extracellular polysaccharide-protein complexes of a harmful alga mediate the allelopathic control it exerts within the phytoplankton community

“…Although there have been various biological and non-biological studies of the distribution and growth of flagellate populations (Erga and Heimdal, 1984;Karentz and Smayda, 1984;Haigh et al, 1992;Smayda, 1997;Miralto et al, 1999;Diehl et al, 2002;Ianora et al, 2004;Bruggeman and Kooijman, 2007), it is not always clear how certain phytoplankton species can come to dominate a community. Empirical approaches to studying the allelopathic effects and inter-specific interactions among phytoplankton have developed relatively slowly (Figueredo et al, 2007;Gentien et al, 2007;Strom, 2008).…”