DOI: https://doi.org/10.3354/meps14879
copiedParental guidance required: investigating the role of adult-juvenile interactions in intertidal shellfish populations
- Li Hao Yeoh
- Simon F. Thrush
- Judi E. Hewitt
- Fabrice Stephenson
- Conrad A. Pilditch
- Rebecca V. Gladstone-Gallagher
ABSTRACT: Adult-juvenile interactions are integral for regulating population dynamics in intertidal shellfish beds. Disturbances that reduce shellfish abundance are becoming increasingly frequent and can disrupt these crucial relationships, affecting population dynamics. We manipulated an adult cockle density gradient (Austrovenus stutchburyi) along 23 intertidal sites across four estuaries to explore how reduced adult density affects juvenile retention, shell growth, and condition. Within each site, we reduced adult cockle densities (>15 mm shell length) from 9 m2 ‘removal’ plots and established ‘non-removal’ plots with ambient densities. Juvenile cockles (8–12 mm shell length) were stained with a calcein marker, reseeded into each plot’s centre (0.5 m2), and then sampled after seven months. We hypothesised that relationships between adult cockle density and juvenile retention, shell growth, and condition would be non-linear and influenced by hydrodynamic conditions (i.e., wind-wave exposure) and sediment characteristics such as mud content, microphytobenthic biomass, and shell hash. Our statistical models revealed that adult cockle density and wind-wave exposure were important in driving changes in juvenile retention. Adult density was an important predictor of juvenile shell growth but switched from positive to negative effects in high and low mud, respectively. Juvenile condition was predominantly predicted by sediment chlorophyll a content (a proxy for microphytobenthic biomass). Our study highlights that adult-juvenile interactions are positioned within a network of biophysical interactions, making simple cause-and-effect relationships difficult to detect when seeking generality. Whilst complex, these interactions are critical to inform disturbance-recovery dynamics and restoration of cockle beds.
KEYWORDS
Li Hao Yeoh (Corresponding Author)
- Institute of Marine Science, University of Auckland, 1010, New Zealand
Simon Thrush (Co-author)
- Institute of Marine Science, University of Auckland, 1010, New Zealand
Judi Hewitt (Co-author)
- Department of Statistics, University of Auckland, 1010, New Zealand
Fabrice Stephenson (Co-author)
- School of Natural and Environmental Sciences, Newcastle University, NE17RU, United Kingdom
Conrad Pilditch (Co-author)
- Institute of Marine Science, University of Auckland, 1010, New Zealand
Rebecca Gladstone-Gallagher (Co-author)
- Institute of Marine Science, University of Auckland, 1010, New Zealand
Handling Editor:
Omar Defeo, Montevideo, Uruguay
Reviewers:
3 anonymous referees