Most marine animals have complex life cycles, with two stages — the familiar adult stage, and tiny dispersive stages (usually larvae) that disperse through the plankton. The role of these larval stages received considerable attention from marine ecologists in the 1980s and 1990s, because populations of many species, including many commercially important ones, are limited by the recruitment of these larval stages. Recruitment of most species is also highly variable in space and time, and explaining this variability is central to understanding population fluctuations and helping resource managers maintain or enhance commercially exploited or vulnerable species.
Do larval experiences in the plankton influence their success later in life?
One intriguing suggestion that emerged in the marine ecological literature was that experiences of larvae in the plankton “carry over” to affect their fate later in life. This contrasts with earlier views that because marine animals undergo such massive tissue reorganisation during metamorphosis, they start life afresh after settlement.
We showed a wide range of sources of carry-over effects:
- We provided the first demonstration that exposure to pollutants during the larval stage can have serious effects that show up months later in the adults.
- For a range of species, the energy resources invested in each larva by its maternal parent affects its ability to swim for sustained periods, its responses to settlement cues, and its growth and survival after metamorphosis.
These results support the view that settling larvae are not a pool of similar organisms, but a heterogeneous collection reflecting parental investment, exposure to stresses, and time spent in the plankton.
Life history and ecology of sessile invertebrates
The two-phase nature of invertebrate life histories raises interesting questions about the links between larval and adult stages. Larval condition at settlement can have far-reaching effects on post-metamorphic success, influencing growth, survival, and the timing and extent of reproduction. Larval quality in turn depends on parental — particularly maternal — investment, and on larval experiences during dispersal. We addressed these questions with a number of model species, most notably bryozoans.
Keough Lab 