These data represent critical habitat proposed for designation (November 30, 2023) under the Endangered Species Act for the coral Isopora crateriformis at 3 island units in American Samoa (Tutuila, Ofu & Olosega, and Ta'u). Please refer to the Code of Federal Regulations and the supporting information report for more details and consider the regulatory language when using these spatial data.

https://www.fisheries.noaa.gov/action/proposed-rule-designate-critical-habitat-indo-pacific-corals

Specific areas of critical habitat for the Indo-Pacific coral species Isopora crateriformis proposed for designation include marine area around 3 island units in American Samoa (Tutuila, Ofu & Olosega, and Ta'u) with suitable hard-bottom habitat within the depth range 0-20 m, as described below.

Specific areas of critical habitat were delineated in four steps: (1) General information was used to delineate soft vs. hard substrates, leaving only hard substrate areas; (2) for the hard substrate areas identified in Step 1, specific substrate information was used to delineate unsuitable vs. suitable hard substrates, leaving only the latter; (3) for the suitable hard substrate areas identified in Step 2, we used water quality information to further delineate suitable vs. unsuitable areas; and (4) from the suitable areas identified in Steps 1-3, we removed any overlapping artificial substrates and managed areas. The four steps were implemented for each of the 18 units as follows:

1. For Step 1, we used comprehensive hard-soft substrate maps developed by PIFSC (PIFSC 2021) to delineate soft vs. hard substrates, leaving only hard substrate areas within the combined depth ranges of all listed species in each unit for 16 of the 18 units. For Wake Atoll, we used the substrate map from PIBHMC (2021). For French Frigate Shoals, we used the geomorphological structure component of the maps developed by NCCOS (2003).

2. For Step 2, we started with the hard substrate areas identified in Step 1, then distinguished unsuitable vs. suitable hard substrates. Many hard substrates are unsuitable because: (1) highly-fluctuating physical conditions cause extreme changes in water quality (e.g., shallow pavement and rubble, especially on reef flats); (2) water motion continuously mobilizes sediment (e.g., pavement with sand channels) or unstable substrate (e.g., rubble); or (3) flat, low-relief areas provide poor settlement and growth habitat (e.g., pavement). Removal of these areas left suitable hard substrates, including spur-and-groove, individual patch reef, aggregate reef, aggregated patch reef, scattered coral/rock, and rock/boulder. For this step, primary information sources were Brainard at al. (2008, 2012, 2019), NCCOS (2003, 2005, 2010), PIBHMC (2021), PIFSC (2021), the detailed public comment letters from the Territories (AS DMWR 2021, CNMI DLNR 2021, Guam DOAG 2021), and the American Samoa, Guam, CNMI, PRIA, and NWHI chapters in Waddell and Clarke (2008). Additional sources for individual units are cited in the unit sections below.

3. For Step 3, starting with the suitable hard substrate areas identified in Step 2, we used water quality information to further delineate suitable vs. unsuitable areas. Some of the areas identified in Step 2 are chronically subject to pollution such as excessive nutrients, excessive sediment, contaminants, or other water quality problems, making them unsuitable. Generally, such areas occur in enclosed lagoons and inner harbors where there is high runoff and limited water circulation. Outside of such areas, point and non-point sources of pollution generally do not overlap with suitable hard substrates because wastewater outfalls are located on soft substrates beyond the reef slopes, and stormwater and freshwater discharge occurs primarily on soft substrates (sand or mud) or unsuitable ard substrates (pavement or rubble) along or near shorelines. For this step, primary information sources were Brainard at al. (2008, 2012, 2019), EPA (2021a-f), the detailed public comment letters from the Territories (AS DMWR 2021, CNMI DLNR 2021, Guam DOAG 2021), Territory water quality assessments (AS EPA 2020, CNMI BECQ 2018), and sources for individual units cited in the unit sections below.

4. For Step 4, from the suitable areas identified via the above three steps, we removed any artificial substrates and managed areas, because they do not provide the essential feature, as explained in section 3.2.3 above. This only applies to existing artificial substrates and managed areas, not proposed or planned artificial substrates and managed areas.

For more details and complete citations see the Critical Habitat Information Report: https://www.fisheries.noaa.gov/s3/2023-11/03-coral-critical-habitat-report-20231114-final.pdf

Links to the full text of the proposed rule in the Federal Register and other supporting materials can be found here: https://www.fisheries.noaa.gov/action/proposed-rule-designate-critical-habitat-indo-pacific-corals