Larval dispersal in a changing ocean with an emphasis on upwelling regions

Abstract

Dispersal of benthic species in the sea is mediated primarily through small, vulnerable larvae that must survive minutes to months as members of the plankton community while being transported by strong, dynamic currents. As climate change alters ocean conditions, the dispersal of these larvae will be affected, with pervasive ecological and evolutionary consequences. We review the impacts of oceanic changes on larval transport, physiology, and behavior. We then discuss the implications for population connectivity and recruitment and evaluate life history strategies that will affect susceptibility to the effects of climate change on their dispersal patterns, with implications for understanding selective regimes in a future ocean. We find that physical oceanographic changes will impact dispersal by transporting larvae in different directions or inhibiting their movements while changing environmental factors, such as temperature, pH, salinity, oxygen, ultraviolet radiation, and turbidity, will affect the survival of larvae and alter their behavior. Reduced dispersal distance may make local adaptation more likely in well‐connected populations with high genetic variation while reduced dispersal success will lower recruitment with implications for fishery stocks. Increased dispersal may spur adaptation by increasing genetic diversity among previously disconnected populations as well as increasing the likelihood of range expansions. We hypothesize that species with planktotrophic (feeding), calcifying, or weakly swimming larvae with specialized adult habitats will be most affected by climate change. We also propose that the adaptive value of retentive larval behaviors may decrease where transport trajectories follow changing climate envelopes and increase where transport trajectories drive larvae toward increasingly unsuitable conditions. Our holistic framework, combined with knowledge of regional ocean conditions and larval traits, can be used to produce powerful predictions of expected impacts on larval dispersal as well as the consequences for connectivity, range expansion, or recruitment. Based on our findings, we recommend that future studies take a holistic view of dispersal incorporating biological and oceanographic impacts of climate change rather than solely focusing on oceanography or physiology. Genetic and paleontological techniques can be used to examine evolutionary impacts of altered dispersal in a future ocean, while museum collections and expedition records can inform modern‐day range shifts.

Coupling and Decoupling of Reproduction and Larval Recruitment

“…By considering both larval mortality and dispersal, my review demonstrates that coupling as a whole is common, which reinforces the conclusions drawn regarding the implications of larval retention being common. Climate change will affect both larval dispersal and mortality, but the effect on coupling of reproductive output and larval recruitment likely will depend on life histories, with planktotrophs, calcifiers, poor swimmers and habitat specialists being most affected (Bashevkin et al 2020).…”

Costs and compensation in zooplankton pigmentation under countervailing threats of ultraviolet radiation and predation

“…We provide evidence for the impacts of weather (sunniness) and UVR on selective planktivory, vertical position, and behavioral color change in crab larvae. A better understanding of the factors determining the survival and vertical migrations of larvae will be key to constructing better mechanistic models of larval survival and dispersal under current conditions and future climate change scenarios (Bashevkin et al 2020b). More broadly, these results improve our understanding of the selective pressures acting on pigmentation and vertical distribution of holoplankters as well as meroplankters in both freshwater and marine systems.…”

Often Overlooked: Understanding and Meeting the Current Challenges of Marine Invertebrate Conservation

“…because longer pelagic larval duration gives the individuals more time to reach an appropriate habitat, but every day adrift increases the probability of being eaten (Bashevkin et al, 2020). This larval development is one of the most significant eco-evolutionary traits, with implications for conservation and society (Treml et al, 2015;Fuchs et al, 2020).…”

“…This is going to have implications for population connectivity and survival rates, which will make pinpointing areas of conservation and discerning which species will be affected more difficult. Not only will changing physical oceanographic processes impact transport, but larvae are more sensitive to shifts in water parameters such as temperature, salinity, and turbidity than adults; the consequences of these changes force larvae to contend with lack of food, hypoxia, and warming that most species may not be able to adapt to (Pandori and Sorte, 2018;Bashevkin et al, 2020). Stress tolerance has been shown to increase as marine invertebrates mature and develop their physiological responses (Pörtner and Farrell, 2008), so future research should work toward understanding species' tolerance thresholds to various abiotic factors at different stages in their development.…”