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Home My WebLink AboutMarine Resource SurveyMARINE RESOURCE SURVEY VIRGINIA KEY - RICKENBACKER MARINA 3301 Rickenbacker Causeway Key Biscayne, Florida 33149 Section 17 — Township 54S — Range 42E Prepared for: City of Miami Department of Capital Improvements 444 SW Second Ave, 8 Capital Miami, FL 33130 Prepared by: T—YLINJI\j T E-ki 201 Alhambra Circle, Suite 900 Coral Gables, Florida 33134 November 16, 2012 City of Miami Marine Resource Survey -Virginia Key TABLE OF CONTENTS 1.0 INTRODUCTION......................................................... 2.0 SITE DESCRIPTION ..................... November 16, 2012 3.0 MARINE RESOLTRCE SURVEY .................................................. 3.1 Marine Resource Mapping and Survey Methodology ........ 3.2 Marine Resource Survey Results ........................................ 4.0 CONCLUSIONS List of Tables Table 1 Classification System Used for Mapping of Benthic Habitat. Table 2 Seagrass Species Percent Cover, Abundance, and Density Table 3 Estimated Acreage for Each Habitat Classification. List of Figures Figure 1 Site Map Figure 2 Marine Resource Map .....................1 City of Miami November 16, 2012 Marine Resource Survey -Virginia Key 1.0 Introduction The City of Miami Department of Capital Improvements proposes to develop a master plan for the extension of the Rickenbacker Marina at Virginia Key. In order to meet regulatory requirements, and to assist in the development of the master plan, a benthic resource survey must be performed between July 1 and September 30 within the proposed project area. TY Lin International I HJ Ross (TYLI I HJR) was contracted by the City of Miami to provide environmental services for a marine resource survey. TYLI I HJR, along with their sub -consultant RS Environmental, conducted a marine resource survey at the Rickenbacker Marina located at 3301 Rickenbacker Causeway, Key Biscayne, Florida. 2.0 Site Description The project site is located on the northwest side of Virginia Key within the Biscayne Bay Aquatic Preserve. The site includes an existing full service marina with approximately 190 wet slips and mooring areas and 298 dry slips. The survey area included the existing marina and the area of potential expansion for a total of 42.45 acres (Figure 1). 3.0 Marine Resource Survey A marine resource survey was conducted between September 25 to 27, 2012 with additional survey work completed on November 1, 2012, to document marine resources within the Rickenbacker Marina and the potential expansion area (Figure 1). Following the National Marine Fisheries Service (NMFS) Johnson's seagrass protocol for large sites (2002), a diver visual assessment survey methodology was used to document benthic resources and habitat types, including seagrasses, macroalgae, sponges, corals, and bottom types (i,e., sand). 3.1 Marine Resource Mapping and Survey Methodology After an overall site reconnaissance survey, 18 transects were surveyed within the Rickenbacker survey site. A stratified approach was used where transects were laid every 50 meters outside of the marina. Inside the marina, due to the presence of Johnson's seagrass (Halophila johnsonil), transects were spaced on average every 30 I City of Miami November 16, 2012 Marine Resource Survey -Virginia Key meters. Transect positions were recorded using Hypack Navigational software and Differential Global Positioning System (DGPS) with greater than 1 -meter accuracy. Marine resource data including the location, occurrence, abundance, and density of marine seagrass species were collected at 5 -meter intervals along each transect within a 1M2 quadrat. Each quadrat was further subdivided into 100 10cm2 sub -units. Data recorded within each 1M2 quadrat included seagrass species present, the number of sub -units containing at least one shoot, an average cover abundance score (Braun- Blanquet, 1965), a description of substrate type, and any other observations considered useful (e.g., macroalgae). The cover abundance scale is shown below. Braun-Blanquet scale values: 0.1 = Solitary shoots with small cover 0.5 = Few shoots with small cover 1.0 = Numerous shoots but less than 5% cover 2.0 = Any number of shoots but with 5-25% cover 3.0 = Any number of shoots but with 25-50% cover 4.0 = Any number of shoots but with 50-75% cover 5.0 = Any number of shoots but with >75% cover A line point intercept (LPI) survey was performed along a one -meter wide swath of the transect to document transition between habitat types (i.e., sand, seagrass) and to document notable features that did not fall within quadrats. Both the quantitative and qualitative data were used to create the habitat cover map (Figure 2). Table 1 shows the habitat classification used in the Rickenbacker Marina survey. 2 City of Miami Marine Resource Survey -Virginia Key November 16, 2012 Table 1: Classification System Used for Mapping of Benthic Habitat Habitat Classification Description Halophila decipiens Monospecific bed of this species Halophila johnsonii Monospecific bed of this species Halodule wrightii Monospecific bed of this species Syringodium filiforme Monospecific bed of this species Thalassia testudinum Monospecific bed of this species H. decipiens / T. testudinum Mixed beds H. wrightii / S. filiforme Mixed beds H. wrightii / T. testudinum Mixed beds H. wrightii/H. johnsonii Mixed beds H. wrightii / S, filiforme / T. testudinum Mixed beds Shelly sand with macroalgae Shelly sand with macroalgae with occasional rubble material; may also contain occasional sponge and/or coral Sand Sand, no vegetation Muddy sand Muddy sand, no vegetation 3.2 Marine Resource Survey Results The marine resources at the Rickenbacker Marina survey site included seagrasses, shelly sand with macroalgae, sand, and muddy sand habitat classification categories (Figure 2). The federally threatened Halophila johnsonii (Johnson's seagrass) was documented within the existing marina. Other seagrasses were typical of the area and included Halodule wrightii (Shoal Grass), Syringodium filiforme (Manatee grass), Halophila decipiens (Paddle grass), Thalassia testudinum (Turtle grass) in single or mixed beds. Macroalgae documented included Batophora, Avrainvillea, Halimeda, Udotea, Dictyota, Caulerpa, Penicilus species and red macroalgae. Sponges identified included Ircinia. Several hard coral colonies were documented in the southwestern portion of the survey area, including Solenastrea bournoni and Siderastrea siderea. 3 City of Miami November 16, 2012 Marine Resource Survey -Virginia Key Braun-Blanquet data were used to describe the percent cover, abundance and density of the seagrasses across transects at the Rickenbacker Marina site and is shown in Table 2. Acreages of resource types were also estimated using transect data and are presented in Table 3. 4.0 Conclusions The majority of the study area (29.46 acres) is comprised of shelly sand with macroalgae, sand, and muddy sand, particularly in the northwest of the study area and within the existing marina. Of the 42.4-5 acre survey area, approximately 12.638 acres contained monospecific and mixed beds of five seagrass species. Several hard coral colonies were documented in the southwestern portion of the survey area and included Solenastrea bournoni and Siderastrea siderea. Halodule wrightii was found to be the most abundant seagrass species present with 2.666 acres of monospecific beds and 7.069 acres within mixed beds. It was found in over 14 percent of the quadrats. Braun-Blanquet data for H. wrightii abundance and density were also the highest at 1.74 and 0.76, respectively. The federally Threatened Halophila johnsonii was detected in 0.08 percent of the quadrats surveyed. H. johnsonii was found within the existing marina and included a small monospecific bed of 0.005 acres and a mixed bed consisting of H. johnsonii and H. wrightii of 0.158 acres. M City of Miami Marine Resource Survey -Virginia Key November 16; 2012 Table 2. Seagrass Species Percent Cover, Abundance, and Density Species Percent Cover Abundance Density Halodule wrightli 14.23 1.74 0.76 Halophila decipiens 0.03 0.50 0.01 Halophila johnsonii 0.08 1.00 0.04 Thalassia testudinum 2.08 1.36 0.11 Syringodium filiforme 6.14 1.37 0.29 Table Notes: Percent cover is the number of occupied subunits /total number of subunits"100. Abundance is the sum of cover scores/total number of occupied quadrats. Deosily is the sum of cover scores/total number of quadrats. Table 3. Estimated Acreage for Each Habitat Classification. Habitat Types Acreage Halophila decipiens 0.018 Halophila johnsonii 0.005 Halodule wrightii 2.666 Syringodium filiforme 0.211 Thalassia testudinum 1.768 H. decipiens / T. teStUdinum 0.901 H. wrightii / S. filiforme 2.536 H. wrightii / H. johnsonii 0.158 H. wrightii/ T. testudinum 3.091 H, wrightii / S. filiforme / T. testudinum 1.284 Shelly sand with macroalgae 15.557 Sand 4.152 Muddy sand 9.751 City of Miami Marine Resource Survey -Virginia Key FIGURES November 16, 2012 Legend Approximate Rickenbacker Marina Survey Sox (42.45 ac.) Survey Transect (2012. DCA) ®9. ft Legend = Approximate Rickenbacker Marina Survey Box (42.45 ac.) H. john sonii/H. wrightii Benthic Habitat Description (DCA, 2012) H. wrlghtfi/S, fiiiforme Halophiia decipiens H. wrightii /T. testudinum Halophila johnsonii H. wrighthIS. filiformelT. te: Haioduie wrightii Shelly sand with macroalgae Syringodium fiiiforme Sand Thalassia testudinum Muddy sand H. decipiens/T. testudinum !�i i 417b ' s• C; Marine Resource Map Marine Resource Survey and Mapping Rickenbacker Marina, Virginia Key, FL Scale: 1 inch = 100 meters Drawn By: MDR Date: November 2012 Approved By: MLR DIAL C ORDY J12-1243 Figure 2