Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Deployments
• Project Information
• Funding

This dataset is from a study examining the influence of structural refuge, competition and their interaction on the early post-settlement survival of transplanted Thalassoma hardwicke (the sixbar wrasse).

This dataset specifically refers to the field experiment used to test how competition with larger residents and structural refuge interact to influence survival of transplanted T. hardwicke. Please see Related Datasets below for additional data associated with this project.

Results from the field assay identified larger Thalassoma quinquevittatum as strongly competing with focal T. hardwicke. A factorial experiment was used to evaluate the effect of competition with larger T. quinquevittatum and the provisioning of structural refuge on the survival of transplanted T. hardwicke. Structural refuge was increased by adding Turbinaria ornata (a structurally complex, locally common, macroalga) to reefs. Twenty reefs were haphazardly selected, with an average surface area of 5.46 m2 (SE = 0.36), a mean height of 0.79 m (SE = 0.03) and isolated from their nearest neighbour by 3.02 m (SE = 0.19). All reefs initially had three to five (mean = 3.38; SE = 0.16) resident Thalassoma quinquevittatum (22.1 mm SL, SE = 0.56) and lacked Turbinaria ornata. The presence/absence of T. ornata was cross-factored with the presence/absence of T. quinquevittatum and treatments were randomly assigned to reefs. On reefs assigned to the presence of T. quinquevittatum, selective removals were conducted so that each reef had three, similarly sized, T. quinquevittatum individuals that were larger than focal T. hardwicke individuals. For T. ornata present treatments, whole T. ornata plants were attached to recipient reefs with cable ties, so that ~15% of habitat cover was T. ornata. Before the experiment, all resident T. hardwicke were removed from the reefs. Three Thalassoma hardwicke individuals (13.69 mm SL, SE = 0.51: collected and tagged as per the field assay) were transplanted onto each reef and their survival surveyed daily (~ 9 a.m.) for five days. Each morning, immigrant T. quinquevittatum (three immigrants were observed) and new T. hardwicke that had settled the previous night (a total of eight settlers) were removed. Neighboring non-experimental reefs were also searched for tagged T. hardwicke immigrants. No tagged immigrants were found; therefore, the disappearance of a tagged fish was assumed due to mortality rather than migration (as for the field assay). Using the same reefs, the experiment was run in two temporal blocks (beginning12 June 2005 and 12 May 2007), yielding ten replicates (five in each temporal block) for each of the four treatments. The mean proportion of T. hardwicke remaining in each treatment on the last day of the experiment was used as the response variable because by the end of each experimental run survival trajectories had stabilized.

Processing notes from the researcher:

This is raw data.

BCO-DMO Processing:

• added conventional header with dataset name, PI name, version date
• modified parameter names to conform with BCO-DMO naming conventions

Description from NSF award abstract:
Ecologists have long been interested in the factors that drive spatial and temporal variability in population density and structure. In marine reef systems, attention has focused on the role of settlement-the transition of pelagic larvae to a benthic stage-and on density-dependent processes affecting recently settled juveniles. Recent data suggest that co-variance in settlement and subsequent density-dependent survival can obscure the patterns of density dependence at larger scales, a phenomenon called cryptic density dependence. This research will explore the mechanisms that underlie the spatial covariance of settlement and site quality - a process that has received little attention in the standard paradigm. These mechanistic studies of cryptic density dependence will facilitate the development of new frameworks for fish population dynamics that incorporate larval ecology, habitat quality, density dependence, life history, and the patterns and implications of spatial covariance among these factors. More generally, the work provides a specific empirical context, and a general theoretical treatment, of cryptic heterogeneity (hidden individual variation in demographic rates).

Note: Drs. Craig W. Osenberg and Ben Bolker were at the University of Florida at the time the NSF award was granted. Dr. Osenberg moved to the University of Georgia during the summer of 2014 (current contact information). Dr. Bolker moved to McMaster University in 2010 (current contact information).