USCG Benthic Report_PR_9Jan2025.pdf

Aids to Navigation Structures in Puerto Rico Benthic Report

Benthic Survey Various Locations

US Coast Guard

USCG Project Number 24878213

USCG Contract No. 70Z05019DBBECPI02

January 09, 2025

ATON Structures in Puerto Rico

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II

Quality information

Prepared by Verified by Lead Verifier

Craig Raffenberg Marine Biologist

Laura Cherney Senior Ecologist

Keith Stannard Associate Vice President

Revision History

Revision Revision date Details

0 12/06/2024 Initial draft submittal to BB&E

1 12/09/2024 Comments from BB&E

2 12/10/2024 Draft incorporating BB&E comments

3 01/09/2025 Document Finalized

III

ATON Structures in Puerto Rico

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US Coast Guard

Civil Engineering Unit Miami

15608 SW 117 Avenue

Miami, FL 33177

Prepared by:

AECOM Technical Services, Inc.

2 Alhambra Plaza, Suite 900

Coral Gables, FL 33134 aecom.com

Prepared in association with:

BB&E

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Northville, MI 48167

Copyright © 2025 by AECOM

All rights reserved. No part of this copyrighted work may be reproduced, distributed, or transmitted in any form or by any means without the prior written permission of AECOM http://www.aecom.com/

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IV

Table of Contents

1.0 Executive Summary .............................................................................................................. 1-1

2.0 Acronyms and Abbreviations .............................................................................................. 2-4

3.0 Introduction ........................................................................................................................... 3-5

4.0 Survey Methodology ............................................................................................................. 4-5

4.1 ATON 1 Survey Area .............................................................................................................. 4-7

4.2 ATON 2 Survey Area .............................................................................................................. 4-8

5.0 Results – ATON 1 Bahia de Guayanilla Entrance Rear Range Light ............................. 5-10

5.1 ATON 1 Structure .................................................................................................................. 5-10

5.2 Benthic/Substrate Characteristics – Physical Setting ........................................................... 5-10

5.2.1 Region 1 – Unconsolidated Sandy Seagrass flats ......................................................... 5-12

5.2.2 Region 2 – Rubble Slope ............................................................................................... 5-12

5.2.3 Region 3 – Hardbottom .................................................................................................. 5-12

5.2.4 Region 4 – Unconsolidated Silt Basin ............................................................................ 5-12

5.2.5 Region 5 – ATON 1 Structure and Footprint .................................................................. 5-13

5.3 Stony Corals .......................................................................................................................... 5-13

5.3.1 Coral Quantity and Area ................................................................................................. 5-13

5.3.2 Coral Locations .............................................................................................................. 5-16

5.3.3 Coral Health ................................................................................................................... 5-16

5.4 Sponges and Octocorals ....................................................................................................... 5-19

5.4.1 Sponges ......................................................................................................................... 5-19

5.4.2 Octocorals ...................................................................................................................... 5-20

5.5 Submerged Aquatic Vegetation: Seagrass and Macroalgae ................................................ 5-20

5.6 Protected Species and Critical Habitat ................................................................................. 5-21

V

5.6.1 Protected Species .......................................................................................................... 5-21

5.6.2 Critical Habitat ................................................................................................................ 5-22

5.7 Additional Species Observations .......................................................................................... 5-25

5.8 Potential for Cultural Resources ........................................................................................... 5-25

6.0 Conclusions – ATON 1 Bahia de Guayanilla Entrance Rear Range Light .................... 6-26

7.0 Results – ATON 2 Bajos Chinchorro Del Sur Light ......................................................... 7-27

7.1 ATON 2 Structure .................................................................................................................. 7-28

7.2 Benthic/Substrate Characteristics – Physical Setting ........................................................... 7-28

7.2.1 Region 1 – Hardbottom .................................................................................................. 7-29

7.2.2 Region 2 – Artificial ........................................................................................................ 7-30

7.3 Stony Corals .......................................................................................................................... 7-30

7.3.1 Coral Quantity and Area ................................................................................................. 7-30

7.3.2 Coral Health ................................................................................................................... 7-35

7.4 Sponges and Octocorals ....................................................................................................... 7-37

7.4.1 Sponges ......................................................................................................................... 7-37

7.4.2 Octocorals ...................................................................................................................... 7-37

7.5 Submerged Aquatic Vegetation: Seagrass and Macroalgae ................................................ 7-41

7.6 Protected Species and Critical Habitat ................................................................................. 7-41

7.6.1 Protected Species .......................................................................................................... 7-41

7.6.2 Critical Habitat ................................................................................................................ 7-42

7.7 Additional Species Observations .......................................................................................... 7-44

7.8 Potential for Cultural Resources ........................................................................................... 7-45

8.0 Conclusions – ATON 2 Bajos Chinchorro Del Sur Light ................................................ 8-45

9.0 Bibliography ........................................................................................................................ 9-48

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VI

List of Figures

Figure 1. ATON 1 Structure ................................................................................................... 5-10

Figure 2. Depth across the ATON 1 survey area moving south to north along the centerline transect. ................................................................................................................................. 5-11

Figure 3. ATON 2 Structure ................................................................................................... 7-28

Figure 4. Depth across the ATON 2 survey area moving west to east along the centerline transect .................................................................................................................................. 7-29

List of Tables

Table 1. Braun-Blanquet Abundance Score Values ..................................................................4-7

Table 2. Bottom Types Observed within the ATON 1 Survey Area .......................................... 5-12

Table 3. Hard Coral Quantities Observed within the ATON 1 Survey Area .............................. 5-14

Table 4. Hard Coral by Size Class (cm) within the ATON 1 Survey Area ................................ 5-15

Table 5. Hard Coral by Location in ATON 1 Survey Area ........................................................ 5-16

Table 6. Hard Coral Health Summary from ATON 1 ................................................................ 5-18

Table 7. Dead Hard Corals Observed in ATON 1 Survey Area................................................ 5-19

Table 8. Octocoral by Size Class (cm) from ATON 1 .............................................................. 5-20

Table 9. Area (ft2) of Density of Observed Seagrass from ATON 1 Survey Area .................... 5-21

Table 10. Protected Species with the Potential to Occur in the ATON 1 Survey Area ............. 5-22

Table 11. Bottom Types Observed within the ATON 2 Survey Area ........................................ 7-29

Table 12. Hard Coral Quantities Observed within the ATON 2 Subsampled Belt Transects and Full Survey Area ..................................................................................................................... 7-33

Table 13. Hard Coral Size Class (cm) within the ATON 2 Subsampled Belt Transects ........... 7-34

Table 14. Hard Coral Health Summary from the ATON 2 Subsampled Belt Transects ............ 7-36

Table 15. Dead Hard Corals Observed from the ATON 2 Subsampled Belt Transects ............ 7-37

Table 16. Octocoral Quantity and Size (Height; cm) from Subsampled Belt Transects in the ATON 2 Northern and Southern Subsections ......................................................................... 7-39

Table 17. Octocorals by Size Class (cm) On, Under, and Within 5 Feet of ATON 2 ................ 7-40

Table 18. Protected Species with the Potential to Occur in the ATON 2 Survey Area ............. 7-42

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VII

List of Appendices

Appendix A – Maps

Appendix B – Representative Photolog

Appendix C – ATON 1 Benthic Quadrat Results

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1-1

1.0 Executive Summary

The United States Coast Guard (USCG) Civil Engineering Unit (CEU) Miami under Contract No.

70Z05019DBBECPI02, issued Task Order No. 70Z08224FCEUM0033 to perform benthic surveys at multiple locations including Miami Beach, St. Thomas, and Puerto Rico. This report discusses two existing Aids to Navigation (ATON) structures in Puerto Rico (separate reports were produced and submitted for the Miami Beach and St. Thomas locations). The two Puerto

Rico ATON sites surveyed are described as follows:

• ATON 1 – Bahia de Guayanilla Entrance Range Rear Light (LLNR 32075) located in the southeastern part of Guayanilla Bay, Lajas, Puerto Rico

• ATON 2 – Bajos Chinchorro Del Sur Light (LLNR 31380) located offshore west of Puerto

Rico between the islands of Vieques and Culebra

The benthic surveys were conducted to identify and document species of stony corals, soft corals/octocoral, sponge, submerged aquatic vegetation (SAV) including seagrass, species listed under the Endangered Species Act (ESA), critical habitat (CH), and hardbottom habitat present within the survey area at each existing ATON structure below mean high water (MHW).

The survey area includes the existing ATON footprint and surrounding 100-foot buffer of sea bottom. Survey methodology was performed in accordance with the Florida Keys National

Marine Sanctuary (FKNMS) Resource Assessment Survey Protocols for Nearshore

Construction Projects (2022). The survey also evaluated the presence or absence of seagrass including documenting species composition, percent cover, and abundance within the survey limits. Seagrass survey protocol followed the Florida Department of Environmental Protection

(FDEP), Guidance on Surveys for Potential Impacts to Submerged Aquatic Vegetation (dated

December 2020) to identify and map SAV within the survey area.

This report describes the methodology and results from the two benthic surveys for each of the existing ATON structures (ATON 1 and ATON 2) in Puerto Rico. The benthic survey at ATON 1 was conducted over four days from November 16 to November 19, 2024. The benthic survey at

ATON 2 was conducted over five days from November 21 through November 25, 2024. The following information summarizes this report:

• The Scientific Dive Team (SDT) completed a benthic resource survey at each ATON site, including documentation of existing hard corals, soft corals, sponges, seagrass, and other species.

• Each survey area included:

o The existing structure of each ATON below MHW o The existing footprint of each ATON o The benthos within 100 feet of each ATON

• Data was collected utilizing belt transects within the survey areas. The total areas surveyed include:

o ATON 1 survey area included a 220-foot by 220-foot square (totaling 48,400 square feet, ft2; 1.1 acres) centered on the ATON 1 structure.

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1-2 o ATON 2 survey area included 46,200 ft2 (1.06 acres). However, due to the large number of resources present in the ATON 2 survey area, a subsample covering

21,000 ft2 (0.48 acres) was completed. The subsample area quantitatively characterized more than 45% of the benthic resources under and around the

ATON 2 structure. The results of the subsample were used to estimate a total number of resources within the survey area. In addition, the SDT swam though 100% of the survey area to confirm presence or absence of seagrasses and other resources.

• SAV including seagrass and macroalgae was observed within the survey footprint.

o ATON 1: Sparse macroalgae cover and varying densities of two species of seagrass were observed at ATON 1 (midrib grass [Halophila baillonis] and turtle grass

[Thalassia testudinum]) for a total seagrass area of 24,788.6 ft2.

o ATON 2: Macroalgae, primarily Y-branch algae (Dictyota spp.) and green algae

(Halimeda spp.), were present in trace amounts at ATON 2 but no seagrass was observed in the survey area.

• Hard corals were identified, located, and measured or estimated by the SDT within the survey area.

o ATON 1: A total of 2,421 hard corals comprised of sixteen species were reported at

ATON 1, totaling 99,387.5 square centimeters (cm2) of coral area.

o ATON 2: A total of 3,876 hard corals (and fire corals) comprised of twenty species were subsampled at ATON 2, totaling 3,067,463.2 cm2 of coral area. Coral counts were scaled up by a factor of 2.2 to estimate coral coverage across the entire

ATON 2 survey area as 8,531 hard corals, totaling 6,749,805.0 cm2 of coral area.

• No ESA-listed coral species were observed at ATON 1. ESA-listed coral species observed at ATON 2 included five species of federally protected coral, mountainous star coral (Orbicella faveolata), boulder star coral (O. franksi), lobed star coral (O. annularis), elkhorn coral (Acropora palmata), and staghorn coral (A. cervicornis).

• Other federally protected species were observed within and surrounding the survey limits including:

o ATON 1: Twenty separate observances of queen conch (Aliger gigas) within the

ATON 1 survey area.

o ATON 2: One A. gigas within the ATON 2 survey area and unidentified species of sea turtles outside of the survey area, a few hundred feet west of ATON 2.

• Total sponge cover was estimated across the survey area.

o ATON 1: Sponges were too numerous to count at ATON 1; therefore total coverage was estimated using quadrats to subsample the areas where observed. Total sponge cover within the ATON 1 survey area is estimated to be 9.14 ft2 (8,488.5 cm2).

o ATON 2: Sponges were recorded during the subsection survey at ATON 2. Based on the subsection transects, sponge cover was recorded as less than 0.01%. Scaled to the full survey area, estimated sponge cover at ATON 2 is 4.62 ft2 (4,292.1 cm2).

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• Total octocoral cover was estimated across the survey area.

o ATON 1: All octocorals within the ATON 1 survey area were measured and identified to species level when possible (otherwise reported at genus level). A total of 67 individual octocoral were observed comprised of eight species.

o ATON 2: Octocorals were recorded during the subsection survey at ATON 2. A total of 8,884 individuals were recorded. Applying the same 2.2 scaling factor, it can be estimated that there are 19,545 octocorals across the entire survey area.

• Construction and/or dredging activities that may impact seagrass, hard corals, sponges and/or octocorals will likely require regulatory coordination including the United States Army Corps of Engineers (USACE), National Marine Fisheries Service (NMFS), and Puerto Rico Department of Natural and Environmental Resources (DNER).

• Work proposed in areas where coral colonies meet relocation size guidelines may require transplantation to an appropriate recipient site, or rescue through local coral rescue organizations or universities for research, coral reproduction, etc. Additionally, mitigation may be required by the regulatory agencies for non-relocatable corals within the impact area to be determined during the permitting process.

• No potential cultural resources were noted. However, manmade objects including the

ATON structures themselves and artificial debris, were observed during the benthic surveys.

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2-4

2.0 Acronyms and Abbreviations

AAUS American Academy of Under Water Scientists

AECOM AECOM Technical Services, Inc.

ATON Aids to Navigation

CEU Civil Engineering Unit

CH Critical Habitat

DNER Department of Natural and Environmental Resources

EFH Essential Fish Habitat

ESA Endangered Species Act

FDEP Florida Department of Environmental Protection

FKNMS Florida Keys National Marine Sanctuary

FWC Florida Fish and Wildlife Conservation Commission

GPS Global Positioning System

IPaC Information for Planning and Consultation

MHW mean high water

MLW mean low water

NMFS National Marine Fisheries Service

NOAA National Oceanographic and Atmospheric Administration

SAV submerged aquatic vegetation

SDT Scientific Dive Team

USACE United States Army Corp of Engineers

USCG United States Coast Guard

USFWS United States Fish and Wildlife Service

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3.0 Introduction

AECOM Technical Services Inc. (AECOM), as part of the BB&E, Inc. team, was contracted by the United States Coast Guard (USCG) to conduct scientific diving in support of proposed facilities improvements. The work was issued by USCG Civil Engineering Unit (CEU) Miami under Contract No. 70Z05019DBBECPI02, Task Order No. 70Z08224FCEUM0033. This report describes the marine benthic survey conducted at two Aids to Navigation (ATON) structures in

Puerto Rico. Separate reports have been prepared for the Miami Beach and St. Thomas survey locations. A brief description of each ATON follows:

ATON 1 – Bahia de Guayanilla Entrance Range Rear Light

ATON 1 is located in the southeastern part of Guayanilla Bay, Lajas, Puerto Rico (17.985274°N, -66.764133°W). The ATON 1 structure is located approximately 600 feet from shore near

PR-337 road in Guayanilla, Peñuelas, Puerto Rico. The ATON 1 structure serves as a range rear light to guide mariners and is situated in twelve feet of water. The survey area was specified to encompass a 100-foot buffer zone around ATON 1 (Appendix A, Figure 1-1).

ATON 2 – Bajos Chinchorro Del Sur Light

ATON 2 is located offshore between the islands of Vieques and Culebra

(18.234275°N, -65.519302°W). The ATON 2 structure is located approximately six miles offshore of Ceiba, Puerto Rico in the Puerto Del Rey Marina. The structure is situated in twelve feet of water and the survey area was specified to encompass a 100-foot buffer zone around

ATON 2 (Appendix A, Figure 2-1).

The designated benthic survey area for each location includes the following elements

(Appendix A, Figure 1-2 and Figure 2-2):

• The existing structure of each ATON below MHW,

• The existing footprint of each ATON, and

• The benthos within 100 feet of each ATON.

4.0 Survey Methodology

The benthic survey was planned and conducted in accordance with the Florida Keys National

Marine Sanctuary (FKNMS) Resource Assessment Survey Protocols for Nearshore

Construction Projects (2022), which requires identification and documentation of hard corals, soft corals/octocoral, sponge, seagrasses and macroalgae (submerged aquatic vegetation

[SAV]), mangroves, Endangered Species Act (ESA) listed species, critical habitat (CH), and hardbottom habitat. The survey was also conducted in accordance with the Florida Department of Environmental Protection’s (FDEP) Guidance on Surveys for Potential Impacts to Submerged

Aquatic Vegetation (2020) to identify, assess, and map the limits of SAV, including seagrass.

The AECOM Scientific Dive Team (SDT) that conducted the survey consisted of four marine biologists endorsed by the American Academy of Underwater Sciences (AAUS) with extensive

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4-6 experience in marine benthic resource, coral and seagrass assessments in South Florida, the

Florida Keys, and the Caribbean Sea. Throughout the extent of the survey, SDT personnel rotated the roles of two divers in the water, one Dive Supervisor/Site Safety Officer that remained on the surface, and one Rescue Diver/Divers Attendant that remained topside ready to deploy as a safety measure and provide the divers with surface support. The benthic survey included Craig Raffenberg, Ashley Matthews, Isaiah Mosley, and James Salafia, all experienced

AAUS divers.

The team of two divers in rotation were outfitted with underwater cameras, slates, data sheets, scale bars marked in centimeters, a one-meter by one-meter quadrat, and six 100/300-foot fiberglass open reel measuring tapes for data collection purposes. The team also utilized a

Trimble R2 Global Navigation Satellite System receiver to establish global positioning system

(GPS) reference points within the survey limits.

At each ATON site, the SDT collected resource and habitat data for the following:

• Location, size (measured in three axes [length, width and height]) and overall health of hard coral, soft coral, and sponges, noting the underlying substrate type (hardbottom, riprap, or artificial debris);

• Following the FKNMS Resource Assessment Survey Protocols for Nearshore

Construction Projects, surface area calculations for corals < 1 cm high are calculated as length by width. Surface area calculations for corals ≥ 1 cm high are calculated as length by width by height. Because the surface area of a dome (or ½ of the surface area of an oblate, prolate, or scalene ellipsoid) cannot be easily expressed by a simple elementary function, the following formula for an ellipsoid was used and the result divided in half to approximate the surface area of a dome:

S 4 [ ( apbp + apcp + bpcp ) / 3 ] 1/p, where p=1.6075 (relative error of at most

1.178%).

• Documentation of habitat characterization by bottom type within each belt transect;

• Documentation of quadrats to quantitatively assess SAV absolute cover, relative cover and substrate characterization;

• Documentation of sponges and octocorals;

• Documentation of observed threatened or endangered species within and directly adjacent to the survey area; and

• Delineation of sandy areas/non-hardbottom areas and hard-bottom substrate defined in the protocols.

Seagrass species composition and density within the quadrats were observed and reported in accordance with the Braun-Blanquet cover abundance by randomly placing one-square-meter

(1 meter by 1 meter) quadrats throughout the survey area. An absolute coverage and relative cover value was assigned to each quadrat for SAV resources (Table 1).

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Table 1. Braun-Blanquet Abundance Score Values

In areas where resources were too abundant to collect individually, quantities were estimated by subsampling in accordance with FKNMS protocols. Specific subsampling procedures are noted by ATON in Section 4.1 and Section 4.2, below. A separate cultural resources survey to identify archaeological resources was not performed as part of the benthic survey.

4.1 ATON 1 Survey Area

The benthic survey at ATON 1 was conducted over four days, from November 16 through

November 19, 2024, with an average of four dives performed per day. Durin the survey, the currents within the survey area were calm, less than one knot, and dive times were not restricted by peak high and low slack tide windows.

An initial two person SDT team created a centerline transect by laying 220 feet of tape from a fiberglass measuring reel in the north/south direction centered at the ATON 1 central support leg, establishing an equal transect over a distance of 110 feet to the north and south of the

ATON 1 central support leg (encompassing the designated 100-foot buffer area). The centerline transect was used to separate the survey area into an eastern and western subsection with the

ATON 1 positioned in the center (Appendix A, Figure 1-2).

The boundaries of the eastern subsection were demarcated by deploying two 110-foot cross transects running perpendicular and east from the northern and southern end of the centerline transect. A second 220-foot long transect was deployed parallel (north/south direction) and 110-feet to the east of the centerline transect to establish the terminal end of the eastern subsection ultimately creating a rectangular survey area. The total demarcated dimensions of the rectangular eastern subsection survey area measured 220 feet by 110 feet totaling 24,200 ft2

(0.55 acre).

Within the survey area boundaries of the eastern subsection, 110-foot-long belt transects running in the east/west direction were established every 5 to 20 feet based on visibility at the time of the survey. To the south of the ATON 1 structure, belt transects were spaced at distances ranging from five to ten feet. To the north of the ATON structure, increased visibility allowed for belt transects to be spaced 20 feet apart. The measuring reels were used as visual aids to document the location of resources and map the boundaries of substrate changes along

Density Value Description

Absent 0.0 Species absent from quadrat

Trace

0.1 Species represented by a solitary short shoot, < 5% cover

0.5 Species represented by a few (< 5) short shoots, < 5% cover

1.0 Species represented by many (> 5) short shoots, < 5% cover

Sparse 2.0 Species represented by 5% - 25% cover

Moderate 3.0 Species represented by 25%- 50% cover

Dense 4.0 Species represented by 50%- 75% cover

Very Dense 5.0 Species represented by 75%-100% cover

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4-8 the benthos to further characterize and delineate benthic habitats. The locations of the belt transects are depicted in Appendix A, Figure 1-2.

The same methodology was repeated on the west side of the centerline transect to establish the boundaries of the western subsection with the same 220 feet by 110 feet rectangular dimensions. Thus, the total survey area inclusive of the east and west subsections was 220-foot by 220-foot square (48,400 ft2; 1.1 acres) centered on the ATON 1 structure. In addition to the belt transects on the benthos, all five legs of the ATON structure were surveyed from the mean high water (MHW) line to the substrate.

The SDT collected resource and habitat data for hard coral, octocoral coral, sponges, and SAV following the standard procedures as outlined above. For the ATON 1 site, it was feasible to measure and identify all hard corals and octocorals individually. Seagrass was delineated and cover quantified using randomly placed one-square-meter (1 meter by 1 meter) quadrats throughout the survey area for a total of 97 deployed quadrats. Locations of each of the quadrats are shown in Appendix A, Figure 1-3. The quadrats were also used to quantify sponge coverage.

4.2 ATON 2 Survey Area

The benthic survey at ATON 2 was conducted over five days between November 21 through

November 25, 2024, with an average of four dives performed per day. The currents within the survey area were calm, less than one knot, and dive times were not restricted by peak high and low slack tide windows.

The ATON 2 structure base was a triangle, with faces points north, southeast, and southwest.

The centerline transect was run along the north face of the ATON 2 footprint to align the survey and to allow the centerline to run across the depth contours. An initial two-person team ran the centerline transect by laying 220 feet of tape from a fiberglass measuring reel in an east/west direction along the northside of the ATON, establishing an equal transect distance over a distance of 110 feet to the west and east of the ATON 2 center point (encompassing the designated 100-foot buffer area). The centerline transect was used to separate the survey area into a northern and southern subsection with the ATON 2 positioned in the southern subsection

(Appendix A, Figure 2-2).

The boundaries of the northern subsection were demarcated by deploying two 100-foot perpendicular cross transects at the western and eastern ends of the centerline transect running north from the centerline. A second 220-foot long transect was deployed parallel (east/west direction) at 100-feet to the north of the centerline transect to establish the terminal end of the northern subsection, ultimately creating a rectangular survey area. The total demarcated dimensions of the rectangular northern subsection measured 220 feet by 100 feet totaling

22,000 ft2 (0.50 acre). The same methodology was repeated to the south of the centerline to establish the boundaries of the southern subsection except the cross transects were 110-feet in length to account for the footprint of the ATON 2 structure and a 100-foot offset beyond the face of the southern ATON structural support leg. The total demarcated dimensions of the rectangular southern subsection measured 220 feet by 110 feet totaling 24,200 ft2 (0.56 acre).

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4-9

Thus, the total survey area was 220 feet by 210 feet (46,200 ft2; 1.06 acres). The northern and southern subsections are depicted in Appendix A, Figure 2-2.

During initial dive operations, it was noted that the survey limits were located in an area dominated by hardbottom habitat with an abundance of hard corals and octocorals. In cases where resources are too numerous to quantify, the FKNMS protocols allow for an estimate using a subsample of the area scaled to the full survey size. A visual inspection via swim-through of the full survey area to confirm the presence/absence of seagrass and other threatened or endangered species is warranted in conjunction with the quantitative subsample transects. Consistent with FKNMS protocols, the dive team first conducted a visual inspection of the entire survey area noting the coral species present (but not the size and quantities of all species observed) and presence/absence of any seagrasses and other protected resources.

Based on the results of the swim-through, twenty 10-foot-wide belt transects were established as the subsample (ten belt transects in the north subsection and ten in the south subsection), biased around the ATON 2 structure, but also spread to capture the various differences across the full survey area.

Within the northern subsection, the ten belt transects were established to provide a representative subsample of the benthic habitat. Each belt transect was 10-foot wide by

100-foot long running in the north/south direction north of the centerline for a total of 10,000 ft2

(0.23 acres) of benthos quantitatively surveyed within the northern subsection (45.5% overall coverage). Within the southern subsection, each of the ten belt transects were established as

10 feet wide by 110 feet long running in the north/south direction, south of the centerline for a total of 11,000 ft2 (0.23 acre) of benthos quantitatively surveyed within the southern subsection

(45.5% overall coverage). In total, 20 belt transects totaling 21,000 ft2 (0.48 acres) of the total

46,200 ft2 (1.06 acres) survey area were subsampled to quantitatively characterize 45.5% of the benthic habitat under and around the ATON 2 structure. The location of belt transects comprising the subsampled area are depicted in Appendix A, Figure 2-2. In addition, the

ATON 2 structure was evaluated for resources between the mean high-water line and the seafloor.

Within each belt transect, measuring reels were used as visual aids to document the location of resources and map the boundaries of substrate changes to further characterize and delineate benthic habitats. Hard corals were identified to the species level, measured in centimeters along three dimensions (length, width, height) and coral health was documented. Representative photographs for each coral species were recorded using underwater cameras. Due to the significant cover of branched finger coral (Porites furcata), this species could not be enumerated. Instead, the total areal cover was determined using a combination of measuring individual branching colonies and estimating area by delineating the extent of P. furcata patches the using one-square-meter (1 meter by 1 meter) quadrats to determine percent cover. Soft coral cover even within the subsample was too numerous to measure individually. Therefore, coverage of soft coral within each belt transect was quantified within a 10-foot section of each transect. Soft coral average size, maximum size, and health were documented on data sheets and photographs. In addition, all soft coral observed on the ATON 2 structure, and within five feet of the immediate footprint of the ATON structure, were documented and hand measured to provide size class information.

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5.0 Results – ATON 1 Bahia de Guayanilla Entrance Rear

Range Light

The benthic survey at ATON 1 was conducted over four days from November 16 to November

19, 2024. Weather conditions during the survey were generally calm and favorable, with generally light winds and clear skies, though a few rain bands did pass through the area. The water temperature was approximately 87 degrees Fahrenheit (°F). Underwater visibility ranged between 10 and 20 feet.

5.1 ATON 1 Structure

The underwater structure of ATON 1 was comprised of five support legs including a central support leg and four surrounding support legs approximately orientated in each cardinal direction and positioned approximately six feet from the central support (Figure 1). Support struts approximately three to five feet below the surface connected each of the five support legs.

Significant corrosion of the metal structural support legs could be seen at approximately two feet above the waterline (Figure 1).

Figure 1. ATON 1 Structure

5.2 Benthic/Substrate Characteristics – Physical Setting

This section describes the physical setting, characteristics, and bottom types within the survey area of ATON 1. The survey area, as depicted in Appendix A, Figure 1-2, totaled a footprint of

48,400 ft2 (1.1 acres), exclusive of the faces of the ATON 1 structure, which was also surveyed.

Water depths gradually increase from 9 to 13 feet when moving south along the centerline transect from the northern end towards the ATON 1 structure. The ATON 1 structure is situated at the edge of a steep slope on its southern side with depths dropping to 36 feet before leveling out towards the southern end of the centerline transect. An approximate depth profile along the

N

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5-11 centerline of the survey is shown in Figure 2, which depicts the depth across the survey area where a start distance of 0 feet is at the southern end of the centerline transect and the end distance of 220 feet marks the northern end of the centerline transect.

Figure 2. Depth across the ATON 1 survey area moving south to north along the centerline transect.

The overall survey area was observed to consist of four benthic substrate habitat types listed in

Table 2. These include unconsolidated (sandy), unconsolidated (silty), rubble, and hardbottom, which were closely correlated with water depth. The dominant bottom habitat type observed within the survey area consists predominately of unconsolidated sediment comprised of either fine grain sand or silt. Rubble habitat consists of predominantly calcium carbonate (coral skeleton) rubble ranging in size from 1 to 70 centimeters. Hardbottom habitat as defined in the

FKNMS Protocols is an area of natural consolidated hard substrate that is suitable to support corals, coral larval settlement, reattachment, and recruitment of asexual coral fragments. These areas of hardbottom or dead coral skeleton are sufficiently free from fleshy or turf macroalgae cover and sediment cover to allow coral settlement.

Based on depth and benthic substrate characteristics, the survey area was divided into five regions, each with unique benthic habitat characteristics. These regions are shown in

Appendix A, Figure 1-4. Representative photographs depicting the observed benthic habitats throughout the survey area are included in Appendix B, Representative Photolog. The five regions are defined as follows:

• Region 1 – Unconsolidated Sandy Seagrass Flats

• Region 2 – Rubble Slope

• Region 3 – Hardbottom

• Region 4 – Unconsolidated Silt Basin

• Region 5 – ATON 1 Structure and Footprint

0 20 40 60 80 100 120 140 160 180 200 220

D e p th fe e t)

Distance Along Center Transect Line (feet)

ATON 1

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Table 2. Bottom Types Observed within the ATON 1 Survey Area

Bottom Type Total Area (ft2)

Unconsolidated (sandy) 23,910.6

Unconsolidated (silty) 16,712.6

Rubble 6,208.3

Hardbottom 1,568.6

Total 48,400.0

5.2.1 Region 1 – Unconsolidated Sandy Seagrass flats

The dominant bottom habitat type in the shallow (approximately 9 to 12 feet deep) survey area north of the ATON 1 structure in the eastern and western subsections was an unconsolidated sediment consisting of a fine grain silt/sand mixture with small shell fragments, and occasional but rare small pieces of coral/rock rubble. This sandy unconsolidated sediment was dominated by dense seagrass and trace macroalgae cover (discussed below in Section 5.5).

5.2.2 Region 2 – Rubble Slope

Rubble predominately comprised of coral skeleton occurred along the steeply sloping survey area which begins at approximately 12 feet of water depth at ATON 1, deepening in the southward direction to approximately 32 feet. The rubble slope stretched across the eastern and western subsections of the survey area. While loose and not consolidated, the relatively low energy of the bay appeared to allow coral settlement and growth on the rubble without it overturning or moving to a significant degree. The deeper regions of the slope exhibited substantial accumulation of unconsolidated silty sediments, characterized by the presence of exposed rubble at the surface.

5.2.3 Region 3 – Hardbottom

Intrusions of hardbottom habitat exist along the rubble slope to the south of ATON 1, as described above in Region 2. These hardbottom areas range in depths from 12 to 30 feet. A substantial area of hardbottom habitat was observed in the western subsection near the edge of the survey area. This western area south of ATON 1 is predominately hardbottom small packets of sandy/silty infill in low lying areas. Larger-sized corals were observed attached directly to hardbottom substrate.

5.2.4 Region 4 – Unconsolidated Silt Basin

The rubble and hardbottom habitat as described above in Regions 2 and 3 transitions to a very fine unconsolidated silt near the bottom of the sloped southern survey area across the western and eastern subsections. The deeper regions of the southern survey area (depths below approximately 32 feet) are marked by decreased visibility due to the suspension of the fine particles. This area was almost devoid of all resources, except scattered trace amounts of seagrass (discussed below in Section 5.5).

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5.2.5 Region 5 – ATON 1 Structure and Footprint

ATON 1 is situated on the top of the rubble slope between Region 1 and Regions 2, 3 and 4.

The footprint of ATON 1 lies within an area of unconsolidated sandy sediments, but seagrass was absent from the structure footprint area. Artificial metal debris with corals attached were present within the footprint. The structure itself provided a substrate for sparse amounts of hard corals, octocorals, and sponges.

5.3 Stony Corals

5.3.1 Coral Quantity and Area

A total of 2,421 hard corals, also known as stony corals (Scleractinian), were observed and measured throughout the ATON 1 survey area, totaling 99,387.5 cm2 of coral area. The observed hard corals consisted of 16 different coral species. None of the species identified

(Table 3) are ESA-listed.

The most abundant stony coral by number of individuals was the massive starlet coral

(Siderastrea siderea) with 1,308 individuals and a total area of 62,001.6 cm2. The next most abundant species was the lesser starlet coral (Siderastrea radians) with 398 individuals, followed by the hidden cup coral (Phyllangia americana americana) with 327 individuals.

The majority of observed hard corals were small in size, with 78% of corals measuring 5 cm or less. The only observed hard coral greater than 50 cm was a single knobby brain coral

(Pseudodiploria clivosa) within the 60-69 cm size class. S. siderea was the most numerous coral observed in the larger size classes with 27 individuals greater than 19 cm in length.

Smooth star coral (Solenastrea bournoni) displayed a wide range of sizes with at least one individual in every size class up to 49 cm. A list of coral species observed with counts by size class is included in Table 4.

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Table 3. Hard Coral Quantities Observed within the ATON 1 Survey Area

Common Name Scientific Name Quantity Total Area (cm2)

Massive starlet coral Siderastrea siderea 1,308 62,001.60

Lesser starlet coral Siderastrea radians 398 4,309.10

Hidden cup coral Phyllangia americana americana 327 762.7

Mustard hill coral Porites astreoides 197 8,755.50

Smooth star coral Solenastrea bournoni 54 14,284.70

Golfball coral Favia fragum 46 493.5

Blushing star coral Stephanocoenia intersepta 30 1,459.70

Knobby brain coral Pseudodiploria clivosa 21 3,846.40

Symmetrical brain coral Pseudodiploria strigosa 13 882

Boulder brain coral Colpophyllia natans 9 1,015.80

Tube coral Cladocora arbuscula 7 119.4

Artichoke/Solitary disk coral1 Scolymia spp. 5 40.2

Maze coral Meandrina meandrites 2 51.1

Knobby star coral Solenastrea hyades 2 1,262.10

Whitestar sheet coral Agaricia lamarcki 1 86.5

Grooved brain coral Diploria labyrinthiformis 1 17.4

Total 2,421 99,387.50

1These species are visually indistinguishable in the field and are reported at the genus level.

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Table 4. Hard Coral by Size Class (cm) within the ATON 1 Survey Area

Common Scientific 0-5 6-10 11-19 20-29 30-39 40-49 50-59 60-69 Total

Massive starlet coral Siderastrea siderea 935 305 41 24 3 0 0 0 1,308

Lesser starlet coral Siderastrea radians 381 16 1 0 0 0 0 0 398

Hidden cup coral Phyllangia americana americana 327 0 0 0 0 0 0 0 327

Mustard hill coral Porites astreoides 135 53 7 2 0 0 0 0 197

Smooth star coral Solenastrea bournoni 15 22 10 5 1 1 0 0 54

Golfball coral Favia fragum 46 0 0 0 0 0 0 0 46

Blushing star coral Stephanocoenia intersepta 17 10 2 1 0 0 0 0 30

Knobby brain coral Pseudodiploria clivosa 13 6 1 0 0 0 0 1 21

Symmetrical brain coral Pseudodiploria strigosa 9 3 0 1 0 0 0 0 13

Boulder brain coral Colpophyllia natans 6 2 0 1 0 0 0 0 9

Tube coral Cladocora arbuscula 7 0 0 0 0 0 0 0 7

Artichoke/Solitary disk coral1 Scolymia spp. 5 0 0 0 0 0 0 0 5

Maze coral Meandrina meandrites 1 1 0 0 0 0 0 0 2

Knobby star coral Solenastrea hyades 0 0 0 2 0 0 0 0 2

Whitestar sheet coral Agaricia lamarcki 0 1 0 0 0 0 0 0 1

Grooved brain coral Diploria labyrinthiformis 1 0 0 0 0 0 0 0 1

Total 1,898 419 62 36 4 1 0 1 2,421

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5.3.2 Coral Locations

Hard corals were present throughout the ATON 1 survey area where there was sufficient available hard surface to allow coral attachment. As outlined in Section 5.2 the benthic substrate of the survey area was closely correlated with depth (Appendix A, Figure 1-4). The shallow survey area north of ATON 1 in the eastern and western subsection (Region 1 in

Section 5.2) was dominated by unconsolidated sandy substrate and dense seagrass providing limited coral habitat. The 168 corals observed north of ATON 1 (73 in the eastern subsection and 95 in the western subsection) were mainly limited to individuals attached to scattered pieces of rubble (Table 5). The ATON 1 structure (Region 5 in Section 5.2) had limited hard coral cover with only ten individuals present, one mustard hill coral (Porites astreiodes) and nine

S. siderea, on the ATON 1 structure. In addition, one S. bournoni and two S. siderea were identified on the benthos of the ATON 1 footprint.

The majority of hard corals were found on the rubble and hardbottom habitat that occurred in the sloping region of the study area to the south of ATON 1 (Regions 2 and 3 in Section 5.2).

Eighty two percent of the coral cover comprised of 2,243 individuals was recorded in the area south of ATON 1 (Table 5). The majority of these corals (1,821 individuals) were concentrated in the western subsection, as the western survey area provided more rubble and hardbottom habitat compared the eastern survey area with a large presence of unconsolidated silt (Region 4 in Section 5.2).

Table 5. Hard Coral by Location in ATON 1 Survey Area

Survey Area Location Quantity Total Area (cm2)

Eastern Subsection North of ATON 1 73 4,595.7

South of ATON 1 422 2,703.0

Western Subsection North ATON 1 95 12,908.6

South of ATON 1 1,821 78,858.1

ATON 1 Structure Vertical Faces 10 322.1

Total 2,241 99,387.5

5.3.3 Coral Health

Of the 2,421 hard corals observed, 189 individuals or about 8% of the hard corals showed signs of paling or bleaching. As shown in Table 6, 134 total individuals showed signs of paling

(change in coloration), and 54 total individuals showed signs of bleaching (full loss of coloration but with live tissue still present). Only one coral, a S. siderea, was noted as diseased with a large black patch and a clear delineation of paling tissue. The disease may have been

Caribbean ciliate infection, a photograph showing the black patch and ring of white tissue is included in Appendix B, Representative Photolog. Nearly half of the observed P. astreoides individuals showed signs of bleaching (30 individuals) or paling (61 individuals). Healthy golfball corals (Favia fragum) were less prevalent than pale or bleached (13 healthy, 10 paling, 23 bleached). Other species of bleached or pale corals included S. siderea, S. radians, S. bournoni, blushing star coral (Stephanocoenia intersepta), and P. clivosa.

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In addition to the live hard corals observed, 154 dead hard coral skeletons were found with no live tissue in various levels of early algal overgrowth (see Table 7). These dead individuals are not included in the coral quantities reported above. The majority of dead corals were F. fragum with 141 observed dead individuals with an area of 1,554.4 cm2. Half of the total area of dead coral was comprised of two large dead boulder brain coral (Colpophyllia natans) totaling

2,227.40 cm2.

There was no clear pattern in the location of these corals with deteriorating health. Significant turbidity was noted in the survey area, especially in areas adjacent to the silt basin (Region 4 in

Section 5.2) at the southern end of the survey area. Further, the local dive shop indicated that they have observed extended periods of elevated water temperatures in the area.

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Table 6. Hard Coral Health Summary from ATON 1

Healthy Paling Bleached Diseased

Common Name Scientific Name Quantity

Total Area (cm2)

Quantity Total Area (cm2)

Quantity Total Area (cm2)

Quantity Total Area (cm2)

Massive starlet coral Siderastrea siderea 1,303 61,228.2 4 286.8 0 0 1 486.6

Lesser starlet coral Siderastrea radians 350 3,779.7 48 529.4 0 0 0 0

Hidden cup coral Phyllangia americana americana 327 762.7 0 0 0 0 0 0

Mustard hill coral Porites astreoides 106 5,208.3 61 2,599.9 30 947.3 0 0

Smooth star coral Solenastrea bournoni 47 12,912.8 7 1,371.9 0 0 0 0

Golfball coral Favia fragum 13 120.6 10 87.3 23 285.6 0 0

Blushing star coral Stephanocoenia intersepta 28 1,317.1 2 142.6 0 0 0 0

Mountainous star coral Pseudodiploria clivosa 18 617.9 2 2,950.6 1 277.9 0 0

Symmetrical brain coral Pseudodiploria strigosa 13 882.0 0 0 0 0 0 0

Boulder brain coral Colpophyllia natans 9 1,015.8 0 0 0 0 0 0

Tube coral Cladocora arbuscula 7 119.4 0 0 0 0 0 0

Artichoke/Solitary disk coral1 Scolymia spp. 5 40.2 0 0 0 0 0 0

Maze coral Meandrina meandrites 2 51.1 0 0 0 0 0 0

Knobby star coral Solenastrea hyades 2 1,262.1 0 0 0 0 0 0

Whitestar sheet coral Agaricia lamarcki 1 86.5 0 0 0 0 0 0

Grooved brain coral Diploria labyrinthiformis 1 17.4 0 0 0 0 0 0

Total 2,232 89,421.70 134 7,968.50 54 1,510.70 1 486.6

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Table 7. Dead Hard Corals Observed in ATON 1 Survey Area

Common Name Scientific Name Quantity Total Area (cm2)

Golfball coral Favia fragum 141 1,544.4

Mustard hill coral Porites astreoides 7 534.5

Boulder brain coral Colpophyllia natans 2 2,227.4

Maze coral Meandrina meandrites 1 8.5

Artichoke/Solitary disk coral1 Scolymia spp. 1 6.0

Lesser starlet coral Siderastrea radians 1 25.1

Massive starlet coral Siderastrea siderea 1 17.4

Total 154 4,363.2

1These species are visually indistinguishable in the field and are reported at the genus level.

5.4 Sponges and…