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Physical conditions in coastal ecosystems can vary dramatically in space and time, influencing marine habitats and species distribution. However, such physical variability is often overlooked in ecological research, particularly in coral reef research and conservation. This study aims to quantify fine-scale variability in the physical conditions of a coastal environment to provide critical context for coastal ecosystem conservation and coral reef restoration. By developing and analyzing a 50 m-resolution hydrodynamic model, we characterize the physical oceanographic environment around the tropical island of St. John, U.S. Virgin Islands. Model simulations reveal that tides, winds, and the Amazon and Orinoco River plumes, interacting with the complex coastline and seafloor topography, create significant spatial and temporal variability in the coastal environment. Differences in tidal characteristics between the north and south shores generate strong oscillatory tidal flows in the channels surrounding St. John. The mean flow around the island is predominantly westward, driven by prevailing easterly winds. Water temperature and salinity exhibit variability over relatively smalllengthscales, with characteristic alongshore length scales of 3–10 km, depending on the season. Hydrodynamic conditions also vary across multipletimescales. Strong tidal flows interacting with headland geometry produce transient eddies with strong convergent/divergent flows and variability on the scale of hours. Synoptic-scale flow variations are driven by weather events, while seasonal variations are strongly influenced by the Amazon and Orinoco River plumes. During summer and fall, these river plumes freshen the waters on the south shore of St. John, creating significant salinity differences between the north and south shores. These fine-scale physical variabilities can exert a strong influence on the coastal ecosystem and should be considered in the management of coastal resources. By providing a detailed understanding of the physical environment, this study supports efforts to conserve and restore coastal ecosystems, particularly coral reefs, in the face of dynamic and complex oceanographic conditions.
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Re-connecting ecosystems: Integrating coral reefs into monitoring of island restoration
Ecosystems are intrinsically linked, such that management actions in one ecosystem can influence adjacent ecosystems. However, adequate data, and even protocols, for monitoring cross-ecosystem responses to conservation initiatives are lacking. Here, we evaluate potential indicators, operating on different spatial, temporal, and biological scales, for measuring the effects of island-based restoration on coral reef ecosystems. We show that island restoration status had consistent effects on populations of tropical seabirds across spatial scales from 100 m to entire islands. Seabirds, in turn, provided nutrient subsidies that were incorporated by marine algae and coral-reef fishes, with the most pronounced effects closer to shore, at leeward sites, and at low trophic levels. Microbes and macroalgae exhibited assemblage-level responses to seabird-derived nutrients entering the marine environment, but there were few differences in coral reef benthic and fish assemblages. By identifying and focusing on specific indicators such as macroalgal nutrients, managers can better monitor cross-ecosystem responses to conservation interventions with limited resources.
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- Award ID(s):
- 2224354
- PAR ID:
- 10591801
- Publisher / Repository:
- Ecological Indicators
- Date Published:
- Journal Name:
- Ecological Indicators
- Volume:
- 170
- Issue:
- C
- ISSN:
- 1470-160X
- Page Range / eLocation ID:
- 113042
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.ecolind.2024.113042
