Metabolite benthic

Meroplankton comprise organisms that spend only part of their life in the plankton. Primarily eggs and larvae of benthic or actively swimming adults fulfill this criterion, and the study of their chemical defense is often supported by the knowledge of defensive metabolites of their adult life stages. 

In contrast to our sparse knowledge about the action of chemicals as defense in plankton, the identified metabolites with defined defensive activities from benthic organisms are numerous. Nearly every habitat from the Antarctic [94] to coral reefs [95] has been extensively investigated - often motivated by the... 

These dynamic strategies also play important roles in the chemical defense of benthic organisms. Only in recent years have marine scientists started to apply methods that allow these defensive strategies to be monitored. This opens the field for the identification of signals that play a role in species-species interactions in the marine environment and for the elucidation of hormones responsible for regulating the production of secondary metabolites. 

Importantly, Lindquist et al.53 also document that ascidians can exhibit chemical differences between defensive secondary metabolites among adults and larvae. For example, larvae from colonies of Sigillina cf. signifera contained more tambjamine C, less tambjamine E, and no tambjamine F as compared to adults.65 Moreover, larvae of Trididemnum solidum contain only four of the six didemnins found in adults.53 This could be the result of different selective pressures during planktonic vs. benthic life history phases. In contrast, Lucas et al.44 found no differences in the saponin chemical defenses of the embryos, larvae, and adults of the sea star Acanthaster planci. Clearly, additional studies are needed to expand the evaluation of ontogenetic shifts in defensive chemistry in marine organisms. 

Many of the studies reviewed in this chapter have focused on the meroplankton. However, little is known about ontogenetic shifts in concentrations and patterns of defense in marine invertebrate larval forms.40 Further work is needed to determine if, for a wider range of species, developing larvae are capable of secondary metabolite synthesis or if defensive compounds are derived directly from adults. While a number of studies have been conducted on chemical defenses in lecithotrophic larvae of benthic invertebrates, the database is still quite small for planktotrophic larvae. Additional carefully controlled studies of aposematism in marine invertebrate larvae are also needed to determine if there is indeed a general pattern of chemical defenses in conspicuously colored larvae. 

Further directions for the study of both meroplankton and holoplankton chemical ecology include development of field bioassays to couple with laboratory studies. Studies are needed to determine how consumers may perceive secondary metabolites produced by plankton.166 The ability of planktonic organisms to sequester defensive chemistry in specific tissues or mucus, as seen in benthic invertebrates, is unknown. Very little is known about the specific compounds responsible for chemical defenses in plankton, and we expect the library of secondary metabolites produced... 

The marine environment is a vast resource for the discovery of structurally unique bioactive secondary metabolites, some belonging to totally novel chemical classes.8 Sessile benthic organisms including the Porifera, Cnidaria, Bryozoa, and Tunicata as well as marine algae have developed an arsenal of compounds which have been demonstrated to confer a competitive advantage in ecosystems characterized by extreme resource limitations. Interactions of these organisms at the genetic,... 

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