Document: NRC Regulatory Guide
Document ID: e5306f4f-dc8c-4f60-a71c-af7ad4080384
Document Type: regulatory_guide
Title: Aquatic Environmental Studies for Nuclear Power Stations + HISTORY - HISTORY 12/2014 – DG-4023 -Proposed New Guide
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML1318/ML13186A085.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.24
CFR Part: 
CFR Title: 

Content:
ing, reproduction, and communication), and even physiology and integrity of certain tissues of aquatic animals in the area. Analyses can compare projected noise levels in aquatic habitats near project sites with species noise tolerance levels reported in the scientific literature. Responses reported in the literature vary widely among species and are a function of sound level (measured in decibels), sound duration, and pattern and frequency of occurrence. If quantitative noise data are not available in the scientific literature, analysts may substitute qualitative evaluations to account for the effects of existing background noise. Similarly, changes in pressure and resulting effects on aquatic species should be analyzed quantitatively and/or qualitatively as appropriate. Displacement Analyses It is important to consider how habitat loss and other activities displace aquatic biota from affected habitats to nearby habitats. The receiving habitats may lack the resources or environmental conditions necessary to accommodate the displaced biota, or the displaced individuals may compete for DG-4023, Page 21 limited resources with individuals in the existing community, resulting in net losses to affected populations. Habitats can optimally support only a certain population level, called the carrying capacity. Once a habitat that receives displaced individuals exceeds its carrying capacity, displaced individuals compete for resources until the population returns to the carrying capacity. When a habitat exceeds carrying capacity, the resulting resource depletion can affect other species, thus disturbing delicate equilibriums that underlie food chains, ecological communities, and ecosystems. In many areas of the United States, displacing species can lead to indirect impacts in nearby habitats, such as heavy feeding on vegetation or changes in targeted prey species. A qualitative discussion of possible biotic displacement may be adequate. Analysts should confer with federal,