More Like this

1. Departures from isotropy: the kinematics of a larval snail in response to food

   https://doi.org/10.1242/jeb.239178  

   DiBenedetto, Michelle H. ; Meyer-Kaiser, Kirstin S. ; Torjman, Brooke ; Wheeler, Jeanette D. ; Mullineaux, Lauren S. ( January 2021 , Journal of Experimental Biology)

   null (Ed.)

   ABSTRACT The swimming behavior of invertebrate larvae can affect their dispersal, survival and settlement in the ocean. Modeling this behavior accurately poses unique challenges as behavior is controlled by both physiology and environmental cues. Some larvae use cilia to both swim and create feeding currents, resulting in potential trade-offs between the two functions. Food availability is naturally patchy and often occurs in shallow horizontal layers in the ocean. Also, larval swimming motions generally differ in the horizontal and vertical directions. In order to investigate behavioral response to food by ciliated larvae, we measured their behavioral anisotropy by quantifying deviations from a model based on isotropic diffusion. We hypothesized that larvae would increase horizontal swimming and decrease vertical swimming after encountering food, which could lead to aggregation at food layers. We considered Crepidula fornicata larvae, which are specifically of interest as they exhibit unsteady and variable swimming behaviors that are difficult to categorize. We tracked the larvae in still water with and without food, with a portion of the larvae starved beforehand. On average, larvae in the presence of food were observed higher in the water column, with higher swimming speeds and higher horizontal swimming velocities when compared with larvae without food. Starved larvae also exhibited higher vertical velocities in food, suggesting no aggregation behavior. Although most treatments showed strong anisotropy in larval behavior, we found that starved larvae without food exhibited approximately isotropic kinematics, indicating that behavioral anisotropy can vary with environmental history and conditions to enhance foraging success or mitigate food-poor environments. 

   more » « less
2. Larval cross‐shore transport estimated from internal waves with a background flow: The effects of larval vertical position and depth regulation

   https://doi.org/10.1002/lno.11632  

   Garwood, Jessica C. ; Lucas, Andrew J. ; Naughton, Perry ; Roberts, Paul L. D. ; Jaffe, Jules S. ; deGelleke, Laura ; Franks, Peter J. S. ( October 2020 , Limnology and Oceanography)

   Cross‐shore velocities in the coastal ocean typically vary with depth. The direction and magnitude of transport experienced by meroplanktonic larvae will therefore be influenced by their vertical position. To quantify how swimming behavior and vertical position in internal waves influence larval cross‐shore transport in the shallow (~ 20 m), stratified coastal waters off Southern California, we deployed swarms of novel, subsurface larval mimics, the Mini‐Autonomous Underwater Explorers (M‐AUEs). The M‐AUEs were programmed to maintain a specified depth, and were deployed near a mooring. Transport of the M‐AUEs was predominantly onshore, with average velocities up to 14 cm s⁻¹. To put the M‐AUE deployments into a broader context, we simulated > 500 individual high‐frequency internal waves observed at the mooring over a 14‐d deployment; in each internal wave, we released both depth‐keeping and passive virtual larvae every meter in the vertical. After the waves' passage, depth‐keeping virtual larvae were usually found closer to shore than passive larvae released at the same depth. Near the top of the water column (3–5‐m depth), ~ 20% of internal waves enhanced onshore transport of depth‐keeping virtual larvae by ≥ 50 m, whereas only 1% of waves gave similar enhancements to passive larvae. Our observations and simulations showed that depth‐keeping behavior in high‐frequency internal waves resulted in enhanced onshore transport at the top of the water column, and reduced offshore dispersal at the bottom, compared to being passive. Thus, even weak depth‐keeping may allow larvae to reach nearshore adult habitats more reliably than drifting passively.

    

   more » « less
3. Salinity Conditions during the Larval Life Stage Affect Terrestrial Habitat Choice in Juvenile Wood Frogs (Lithobates sylvaticus)

   https://doi.org/10.1670/20-123  

   Vegso, Zachary T. ; Kalonia, Anila A. ; Stevens, Skyler ; Rittenhouse, Tracy A. ( March 2022 , Journal of herpetology)

   Anthropogenic salinization is a pervasive pollutant in much of the northeastern United States because of the widespread use of chemical deicing agents on roads. Although studies have examined the physiological effects of salinization on amphibians across life stages, behavioral responses to salinization of habitats are less studied. In this study, we experimentally test how salinity and temperature conditions experienced as larvae affect behavioral and physiological responses as juveniles. We first experimentally test whether juvenile Wood Frogs (Lithobates sylvaticus) can detect and avoid road salt in terrestrial soils and whether this avoidance behavior differs depending on temperature and salinity conditions in which individuals were raised as larvae. We also experimentally test whether temperature and salinity conditions experienced as larvae affect desiccation rates in juvenile Wood Frogs. We found a significant correlation between larval salinity conditions and choice of soil, with frogs raised in high salt aquatic conditions spending the majority of time on high salinity soils and frogs raised in low salt aquatic conditions spending the majority of time on low salinity soils. This behavioral response was muted in frogs raised in elevated temperature conditions. We were unable to detect a correlation between larval treatment and desiccation rate. Our experiments demonstrate that Wood Frogs can detect and respond to salinity levels in terrestrial habitats and that this juvenile response depends on environmental conditions experienced as larvae. 

   more » « less
4. Temperature and salinity, not acidification, predict near-future larval growth and larval habitat suitability of Olympia oysters in the Salish Sea

   https://doi.org/10.1038/s41598-020-69568-w  

   Lawlor, Jake A. ; Arellano, Shawn M. ( August 2020 , Scientific Reports)

   Most invertebrates in the ocean begin their lives with planktonic larval phases that are critical for dispersal and distribution of these species. Larvae are particularly vulnerable to environmental change, so understanding interactive effects of environmental stressors on larval life is essential in predicting population persistence and vulnerability of species. Here, we use a novel experimental approach to rear larvae under interacting gradients of temperature, salinity, and ocean acidification, then model growth rate and duration of Olympia oyster larvae and predict the suitability of habitats for larval survival. We find that temperature and salinity are closely linked to larval growth and larval habitat suitability, but larvae are tolerant to acidification at this scale. We discover that present conditions in the Salish Sea are actually suboptimal for Olympia oyster larvae from populations in the region, and that larvae from these populations might actually benefit from some degree of global ocean change. Our models predict a vast decrease in mean pelagic larval duration by the year 2095, which has the potential to alter population dynamics for this species in future oceans. Additionally, we find that larval tolerance can explain large-scale biogeographic patterns for this species across its range.

    

   more » « less
5. Interdisciplinary analysis of larval dispersal for a coral reef fish: opening the black box

   https://doi.org/10.3354/meps13971  

   Counsell, CWW ; Coleman, RR ; Lal, SS ; Bowen, BW ; Franklin, EC ; Neuheimer, AB ; Powell, BS ; Toonen, RJ ; Donahue, MJ ; Hixon, MA ; et al ( February 2022 , Marine Ecology Progress Series)

   Many marine animals have a biphasic life cycle in which demersal adults spawn pelagic larvae with high dispersal potential. An understanding of the spatial and temporal patterns of larval dispersal is critical for describing connectivity and local retention. Existing tools in oceanography, genetics, and ecology can each reveal only part of the overall pattern of larval dispersal. We combined insights from a coupled physical-biological model, parentage analyses, and field surveys to span larval dispersal pathways, endpoints, and recruitment of the convict surgeonfish Acanthurus triostegus . Our primary study region was the windward coast of O‘ahu, Hawai‘i. A high abundance of juvenile A . triostegus occurred along the windward coast, with the highest abundance inside Kāne‘ohe Bay. The output from our numerical model showed that larval release location accounted for most of the variation in simulated settlement. Seasonal variation in settlement probability was apparent, and patterns observed in model simulations aligned with in situ observations of recruitment. The bay acted as a partial retention zone, with larvae that were released within or entering the bay having a much higher probability of settlement. Genetic parentage analyses aligned with larval transport modeling results, indicating self-recruitment of A . triostegus within the bay as well as recruitment into the bay from sites outside. We conclude that Kāne‘ohe Bay retains reef fish larvae and promotes settlement based on concordant results from numerical models, parentage analyses, and field observations. Such interdisciplinary approaches provide details of larval dispersal and recruitment heretofore only partially revealed. 

   more » « less