Table 1.
Potential effects of offshore renewable energy developments in the United States considered to be of greatest importance based on results of a literature review and expert judgment (see Supplementary Appendix A). Effects are organized by ecosystem component and are paired with a proposed indicator of that effect.
| Impact/monitoring objective | Indicator | |
|---|---|---|
| Benthic habitat and resources | Changes to seafloor morphology and structure (compared to preconstruction) | Increase or decrease in seabed volume |
| Changes in median grain size, or organic content | (i) Deposition: decrease in median grain size, increase in organic content, increase in seabed volume (ii) Scour: increase in median grain size, decrease in organic content, decrease in seabed volume |
|
| Turbidity during construction/decommissioning | Change in water column turbidity | |
| Change in target species abundance and distribution (e.g., species of importance) | Change in abundance, diversity, % cover, multivariate community composition | |
| Current speed/direction inside and outside farm | Change in residual flow rates | |
| Reef effects, colonization on foundations | Increase in % cover, biomass of epifaunal organisms; increase in presence of nonnative species | |
| Change in density, diversity, dominance structure of infauna | Change in abundance, diversity, % cover, multivariate community composition | |
|
| ||
| Fish | Reef or aggregation effects | Increase in fish abundance around devices, shift in species composition, increase in presence of nonnative species |
| Changes to abundance/distribution caused by disturbance or habitat alteration | Increase or decrease in fish abundance; increase or decrease in target species; shift in species composition; change in density, diversity, and dominance structure of fish species; increase in presence of nonnative species | |
| Blade strikes/pressure gradients (tidal power) | Observation of blade strike incidents | |
| EMF effects | Not feasible to monitor directly—changes in fish abundance, behavior, or species composition are indicators | |
| Installation or operational noise effects | Not feasible to monitor directly—changes in fish abundance, behavior, or species composition are indicators | |
|
| ||
| Fisheries | Catchability (catch per unit effort) during construction | Catch per unit effort increases or decreases for target species |
| Catchability (catch per unit effort) during operation | Catch per unit effort increases or decreases for target species | |
| Loss of access to grounds | Changes in numbers of vessels fishing near or inside of the renewable energy area, change in the presence of fixed fishing gear inside of or around a renewable energy installation | |
| Changes in species distribution | Shift in species composition, increase in presence of nonnative species | |
| Reef effects (aggregation) | Increase in fish abundance around devices; shift in species composition; increase in presence of nonnative species | |
|
| ||
| Avian | Displacement/attraction | Increase or decrease in avian species-specific densities postconstruction in development area |
| Barrier effects—effects on foraging, roosting, migratory movements | Migrating or commuting birds avoiding developed areas | |
| Collision mortality | Birds found dead or injured due to direct collision with infrastructure above the water | |
|
| ||
| Marine mammals and sea turtles | Vessel strikes | Detection of dead or injured animals |
| Noise generated during construction | Detection of dead or injured animals; changes in distribution, abundance, or behavior of populations | |
| Disturbance or injury during all stages of development, including from vessels | Detection of dead or injured animals; changes in distribution, abundance, or behavior of populations | |
| Noise generated during operation | Changes in distribution, abundance, or behavior of populations | |