ATTACHMENT NO. 9

WETLANDS ASSESSMENT OBSERVATION REPORT CB&I, 2015

WETLANDS ASSESSMENT OBSERVATION REPORT

Date: September 14-15, 2015 Project: 10th Street Outfall Dredging and Stormwater Treatment Design Project Location: 10th Street Boat Basin and Outfall, Sarasota County, Florida Commission No.: 155093.00148126 Field Representatives: Katy Brown (biologist), Cody Bliss (biologist), Adam Harris (field support), and Scott Tillman (captain)

CB&I completed a wetlands assessment in support of the 10th Street Outfall Dredging and Stormwater Treatment Design Project from September 14-15, 2015. The project area is located within the boat basin at Centennial Park and leads into Sarasota Bay (Figure 1). The proposed project includes a stormwater quality retrofit, dredging of the boat basin, and a seawall replacement. This investigation was conducted in order to locate benthic resources (e.g. , oysters) that may be present in and adjacent to the anticipated dredging area and along the existing seawall. This report includes the general conditions, biota observed (including and abundance) and a map showing resource locations. Results from this report will be used in support of project planning and permitting.

Photographs 1-2. 10th Street Outfall Dredging and Stormwater Treatment Design Project Area. Photograph 1 shows location of the outfall in the southeast corner of the boat basin. Photograph 2 shows a close-up of the outfall.

METHODS

Basin Investigation CB&I biologists developed the survey protocol in coordination with FDEP (pers. comm., J. Peterson, 2015). In order to locate potential seagrass resources within the boat basin, biologists surveyed seven (7) transects (TS1-TS7) running north/south and spaced approximately 100 ft. apart (Figure 1). Biologists conducted the survey in a zig-zag pattern to also observe potential seagrass resources between the transects. Depending on the depth of water, which ranged from

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1094500 477500 478000 1094500478500 Notes: Legend: 1. Coordinates are in feet based on the Florida State Transects Plane Coordinate System, West Zone, North American Datum of 1983 (NAD 83). Edge of Seagrass 2. 2014 aerial photography flown by Photo Science, Inc., date flown January 18, 19, 20 & 22, 2015. 3. Seagrass survey was performed by CB&I on £ September 14 &15, 2015. 0100 200 Feet CB&I TITLE: 10th Street Outfall Dredging and 2481 N. W. Boca Raton Blvd. Stormwater Treatment Design Project Boca Raton, FL 33431 Wetland Assessment Ph. (561) 391-8102 Fax (561) 391-9116 September 14-15, 2015 Date: 10/5/15 By: HMVComm. No.: 155093 Figure No.1 G:\Enterprise\Sarasota\155093\Mxd\Project Location Map.mxd Location G:\Enterprise\Sarasota\155093\Mxd\Project approximately 0-6 ft., biologists either swam or walked along (and between) each of the seven transects. When seagrass was observed, the seagrass patch was mapped by a diver towing a buoy equipped with a DGPS antennae along the edge of the seagrass patch. The buoy was on the shortest possible tether, such that the buoy was directly over the diver’s head. The DGPS buoy was connected by a cable to the topside laptop running Hypack navigational software to record positioning data.

After biologists mapped the edge of the seagrass patch they then collected quantitative seagrass data using 0.25 m2 quadrats. Eleven (11) transects (SG1-SG11) were laid across the entire width of the seagrass patch and four (4) quadrats were sampled at evenly spaced intervals along each transect (Figure 2). This method was determined to be the most efficient way to characterize the seagrass patch based on the size and shape of the patch. Two types of seagrass data were collected in each quadrat: (1) the Braun-Blanquet (BB) cover-abundance score was recorded for the total seagrass present and for each species present and (2) the percent cover of total seagrass present and percent cover of each species present was recorded. Also included in the quadrat data were percent cover (genus level) and substrate percent cover. Additional notes were recorded to describe other species (i.e. fish, invertebrates) present, epiphyte load, canopy height, and substrate type. Representative photographs were taken and video was recorded along each of the eleven transects.

Seawall Investigation The seawall that is proposed to be replaced is located on the southern edge of the boat basin; the section to be replaced begins approximately 100 ft. from the southeast corner of the basin and extends approximately 345 ft. west (Figure 1). A biological assessment was conducted along the section of seawall, including 50 feet to the west and north, to document existing biota. Biologists qualitatively assessed the biotic assemblages along the length of the seawall and supplemented observations with photographs and video.

RESULTS

Basin Investigation - Seagrass Resources During the basin investigation, seagrass was only observed at the northern end of Transect TS7 (Figure 1); all of the other transects were characterized by a silty/sandy/mucky substrate. Visibility was extremely poor as this substrate was suspended throughout the water column and any movement only exacerbated the low light and murky conditions.

The observed seagrass resources are located at the mouth of the boat basin along the northern rocky point (Figure 2). For description purposes of this report, the seagrass will be referred to as a patch even though it is more accurately defined as a continuous bed that extends beyond the study area. The seagrass patch delineated during this survey is approximately 0.12 acres; however, the seagrass continues north around the rocky point and along the shoreline of Centennial Park. To approximate the size of the seagrass patch, a line was drawn starting at the northwest terminus of the mapped seagrass edge, continuing due east to the edge of the rocks, around the edge of the rocks, and finally connecting to the other mapped seagrass edge. The

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1095100 1095100 477600 477700 477800 477900 Notes: Legend: 1. Coordinates are in feet based on the Florida State Oyster Bed Plane Coordinate System, West Zone, North American Datum of 1983 (NAD 83). Transects 2. 2014 aerial photography flown by Photo Science, Inc., Edge of Seagrass date flown January 18, 19, 20 & 22, 2015. 3. Seagrass survey was performed by CB&I on £ September 14 &15, 2015. 05025 Feet CB&I TITLE: 10th Street Outfall Dredging and 2481 N. W. Boca Raton Blvd. Stormwater Treatment Design Project Boca Raton, FL 33431 Seagrass Investigation Ph. (561) 391-8102 Fax (561) 391-9116 September 14-15, 2015 Date: 10/5/15 By: HMVComm. No.: 155093 Figure No.2 G:\Enterprise\Sarasota\155093\Mxd\Seagrass Patch Map.mxd Patch G:\Enterprise\Sarasota\155093\Mxd\Seagrass seagrass patch primarily consists of Halodule wrightii (shoal grass); however, there is also (turtle grass) present at the southwestern edge of the patch.

Following delineation of the seagrass patch, 11 transects were surveyed in order to characterize the seagrass resources (Figure 2). Due to the shape of the patch, Transects SG1-SG8 were oriented south/north and Transects SG9-SG11 were oriented west/east. The length of each transect varied based on the location and extent of seagrass present. Table 1 provides seagrass data for Transects SG1-SG11. Overall, there was 38.3 ± 37.9 % mean seagrass cover throughout the patch, and a Braun-Blanquet (BB) Cover-Abundance Scale of 3 (rounded up from 2.7 ± 1.7 %), which is defined as 25-50% cover. Macroalgae (Caulerpa sp.) was only recorded in the 0 m quadrat at the southern end of Transect SG4. The substrate was comprised of silt, sand, and shell and had a mean percent cover of 61.7 ± 37.9 % across all transects. The overall mean canopy height was 20.7 ± 10.1 cm, which includes the one measurement of T. testudinum (without this species the mean canopy height slightly decreases to 20.4 ± 10.1 cm). Appendix A provides all of the quadrat level data for each of the transects. Representative photographs (Photographs 3-8) of the seagrass patch are provided below.

Table 1. Transect level seagrass data are reported by mean with standard deviation. Quadrat Data (100% total cover) Canopy Transect Transect Overall Species Height Seagrass Algae Substrate Length (m) BB Scale (cm) Percent Percent Percent Cover Cover Cover SG1 6 1.8 ± 1.3 H. wrightii 26.0 ± 3.5 13.8 ± 18.0 0 86.3 ± 18.0 SG2 7.4 1.8 ± 1.7 H. wrightii 16.0 ± 10.2 18.5 ± 27.9 0 81.5 ± 27.9 SG3 7 3.3 ± 1.0 H. wrightii 19.0 ± 5.1 46.3 ± 34.7 0 53.8 ± 34.7 SG4 7.5 4.0 ± 1.2 H. wrightii 19.3 ± 5.7 62.3 ± 40.2 0.5 ± 1.0 37.3 ± 39.7 SG5 10 3.3 ± 2.1 H. wrightii 19.3 ± 6.1 48.0 ± 48.6 0 52.0 ± 48.6 SG6 10 3.0 ± 2.4 H. wrightii 18.3± 11.1 52.3 ± 54.1 0 47.8 ± 54.1 SG7 9 3.3 ± 2.1 H. wrightii 23.5 ± 10.7 50.8 ± 48.5 0 49.3 ± 48.5 SG8 5.2 2.6 ± 1.9 H. wrightii 19.8 ± 11.1 35.3 ± 43.5 0 64.8 ± 43.5 SG9 15 2.4 ± 1.5 H. wrightii 17.8 ± 13.2 28.3 ± 28.1 0 71.8 ± 28.1 SG10 8 3.5 ± 1.7 H. wrightii 31.0 ± 12.8 52.5 ± 43.5 0 47.5 ± 43.5 H. wrightii 16.0 ± 15.6 SG11 5 1.4 ± 1.1 13.3 ± 21.3 0 86.8 ± 21.3 T. testudinum 32* Overall - 2.7 ± 1.7 - 20.7 ± 10.1 38.3 ± 37.9 0.0 ± 0.3 61.7 ± 37.9 *Thalassia testudinum was present in only one quadrat on Transect SG11; therefore, only one canopy height measurement was taken.

The condition of the seagrass patch was highly influenced by the silty/sandy substrate present at the site and the seagrass blades all had some degree of sedimentation (Photographs 5-6). Epiphytes were only observed in one quadrat along Transect SG11 and hermit crabs were noted on four of the eleven transects. Dead/drift seagrass was also present within and around the seagrass patch. Videos were taken along each transect to supplement this report in describing the overall condition of the seagrass.

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Photographs 3-8. Representative photographs of the seagrass patch; Halodule wrightii is the only species shown. Photographs 3-4 show the survey methods used; Photographs 5-7 show the influence of sediment on the seagrass within the site; and, Photograph 8 is a close up of H. wrightii.

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Basin Investigation - Hardbottom Resources During the initial survey along Transects TS1-TS7 biologists observed octocorals ( virgulata) along the base of the seawall on a silty/sandy/rocky substrate at the southern end of Transect TS7 (Photographs 9-10). Based on measurements taken of nine L. virgulata colonies, the species had a mean height of 49.4 ± 16.2 cm, with a range from 31 cm to 76 cm.

Photographs 9-10. Octocorals (Leptogorgia virgulata) observed along the base of the seawall at the southern end of Transect TS7.

Oysters (Crassostrea virginica) were observed along the northern edge of the seagrass patch (Figure 2; Photographs 11-12) at the end of Transects SG1-SG7. This intertidal shoreline had mounds of both dead and living oysters surrounded by dead/drift seagrass, rocks, and silty/sand substrate.

Photographs 11-12. Oyster bed located along the northern edge of the seagrass patch.

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Seawall Investigation The seawall survey was conducted at low tide which allowed biologists to walk along the entire extent of the seawall that is proposed to be replaced (Figure 1), including 50 feet to the west and north. Oysters covered the entire base of the seawall up to the high tide line. and crabs were also present along portions of the seawall and no species were observed. (Photographs 13-16)

Photographs 13-16. Oysters and crabs (top right) present along the southern seawall.

REFERENCES

Peterson, Jennifer. 2015. Personal communication between Lauren Floyd (CB&I) and Jennifer Peterson (FDEP) regarding the seagrass monitoring protocol. September 4, 2015.

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