Jacksonville 2013 Reef Pre-Deployment Survey Results

Artificial Reef Pre-deployment Survey

Floyds Folly Permitted Area 7-8-13

Final Report

 sea-robin

 

Prepared for:

The City of Jacksonville
Water Quality Branch
Environmental Quality Division
Environmental & Compliance Dept.
407 N. Laural Street
Suite 300
Jacksonville, FL 32202

 

 

Prepared by:

TISIRI Corp

10752 Deerwood Park Blvd. South
Suite 100
Jacksonville, Fl 32256

 

Summary:

TISIRI identified and surveyed an area of seafloor within the boundaries of the Floyds Folly area (Permitted Area SAJ-2007-261) on 7-8-2013.  The Floyds Folly area may also be referred to as “FF” in the remainder of this document.  Results of the survey efforts suggest the area is adequate to place the anticipated concrete artificial reef materials.  Divers that participated in dive survey and data collection efforts included Joe Kistel, Ed Kalakauskis, Nate Tucei, and Dane Shields.

 

Site Selection:

A location within the FF permitted area was to be identified and surveyed to determine its adequacy to accept concrete artificial reef material.  The site selected and surveyed is referenced in the graphic below.

Zoom-survey-scale-web

 

Originally, an area in the southeast corner of the FF permitted reef zone was thought to be an ideal location to create the upcoming reef.  However during TISIRI’s last pre-deployment survey in 2011 it was noted that this area was a bit shallower than anticipated.  To ensure plenty of vertical clearance it was decided to survey in the northern section of FF due to its ideal depths of over 70 feet.

The area surveyed (noted by the yellow pin in the above graphic) is strategically located just under a half mile from the two previous artificial reef deployments in the permitted zone.  After the reef is placed the three reefs will create a triangle footprint perimeter making it easy for offshore enthusiast to visit all three reefs in one offshore outing. Fishermen are already referring to the overall area as the “Trolling Triangle” as the proximity of the reefs in this geometrical position makes for a convenient trolling pattern.

Prior to conducting the dive survey east-west transects were conducted in a southerly direction with the Native Diver II to survey the area at large with the Furuno depth finder.  This area was over 70 feet deep and appeared flat and free of obvious live bottom according to the sonar instrumentation.  Appearing to be an adequate location from the sonar instrumentation findings, the anchor of the Native Diver was drop precisely at 30° 10.353’      81° 09.460.  The anchor location served as the center point of our survey efforts.  This resulting center point location is roughly .4 miles from the nearest permit line boundary and .4 miles from the nearest known existing reef.

The image below identifies the selected site in reference to the Mayport Jetties and St. Augustine Inlet.  The site is just over 20 miles at a south easterly heading from the mouth of the Jacksonville Jetties and just under 20 miles at a north easterly heading from the mouth of the St. Augustine Inlet.

inlet-perspe-web

 

 

Pre-Deployment Scuba Dive Survey:

Once the site referenced above was identified, 2 diving team pairs entered the water for further site analysis.  Divers performed a 300 foot diameter circular sweep, sampled sediment, observed marine life, photographed/filmed the area, and probed the sea floor.

During the dive efforts a thermo cline was observed at 50 feet and the temperature on the sea floor was about 72°F.  Visibility at the sea floor was estimated to be 15 feet and no significant current was noticed.

 

Radial Sweep Circular Survey:

One dive team had a marked line reel at 150 feet and secured the free end to the anchor.  The anchor served as the benchmark and center point of the area surveyed.  The dive team then traveled at a heading of 0° from the anchor until they reached their 150 foot mark.  They made a mark in the sand here to use a visual reference to know when there survey is completed. From that point the team turned towards the east, and with their real line taught, began to swim easterly.  The dive team swam a giant circle swimming until they returned back to their north starting point (where they made their mark in the sand).  The diameter of the sweep completed was 300 feet. The divers reel was never snagged throughout the entire swim.  This indicated that no obvious signs of live bottom as the real line would have snagged any protrusions sticking out of the sea floor.

Observations:

-          No obvious live bottom such as natural reefs, sponge beds, and/or gorgonian forest were encountered within the 300-foot diameter area swept.

-          The bottom appeared primarily flat with a stiff sandy bottom substrate.  Very little ripples were observed in some areas.

-          The bottom substrate was primarily sand with some larger aggregate including shell pieces.

-          Invertebrate life observed included sea stars, crabs, a tube worm, and jelly fish.

-          The few fish observed included sea robins and juvenile wrasse.

 

Sediment Probing:

A copper ½ inch diameter plumbing pipe was used to randomly probe the sea floor throughout the area surveyed. The sea floor firmness, noted by the depth the probe penetrated the substrate, perhaps provides some indication of future reef materials ability of not sinking into the sea bed.  The diagram below shows the depths of probe penetration at various locations of the surveyed area.  On average, the probe penetrated roughly 6 inches deep indicating a stable substrate.

reef-survey-sweep-results

 

 

Sediment Sampling:

Sediment samples were collected to determine the total composition of sand grain/particulate sizes.  The procedure intent was to use a 1 inch diameter pipe to core vertical samples of sediment however this did not work as expected.  The sea floor had fairly large pieces of aggregate on top of and within the sediment making it difficult to penetrate the sediment with the PVC coring device.  Samples were instead collected using a shovel type method where one scoop of sediment to a depth of about 5-6 inches made up each sample.  Three samples were collected in this fashion in random locations within ten feet of our benchmark location.  The sediment samples were placed in sealed bags with some seawater before being brought to the surface.

Sediment analysis was conducted at the MSRI Laboratory at Jacksonville University. To prepare for sediment analysis, seawater was removed from the three samples and replaced with fresh water.  The freshwater was then decanted and replaced with more fresh water. This procedure was repeated 3 times per sample and after the third addition of fresh water the sediment was allowed to bathe for a period of 12 hours.  The intent of the preceding procedure was an attempt to remove as much organic matter from the samples as possible (to reduce smell) and to also remove salt (as salt would crystallize during the drying process).  After the bathing period, the water was decanted from the sediment samples and the wet samples were placed on aluminum foil in an air condition lab for a period of 36 hours.  This allowed the sediments to dry completely.

The dry samples were run through a series of sieves as described in the table below.  Each individual sieve was weighed using a lab scale prior the application of sediment.  The sieve weight allowed determination of the actual sediment weights remaining in the various sized sieves.  Of course the sediments were run through the sieves in the order of largest opening to smallest open, meaning the biggest aggregates would remain in the 1st sieve and the finest grains would end up in the last sieve.  See the results below.

 

Table 1: Sediment Analysis

 reef-sediment-analysis

The results above indicate nearly 92% of the total sample consisting of large to medium sized sand and aggregate.  The picture shows the distribution of sediment sizes.

 

reef-sediment-distribution

 

Other considerations:

Divers also visited the nearby artificial reef that was deployed in 2009.  The existing reef is approximately .4 miles away (in an east heading) from the surveyed area discussed in this report.  Since the reef to be deployed will consist of the same type of material as the existing reef, observations of the 2009 reef could provide some indication of how the new reef may appear as it matures.

General observations:

-Visibility: 20 feet at the sea floor

-Water temp: at sea floor around 72 degrees

-Some of the fish encountered included Tomtates, flounder, barracuda, Amberjack, Gag Grouper, and Black Sea Bass.

-Reef material had obvious evidence of encrusting growth including small establishments of stony coral colonies

-The most densely populated fish species were the tomtates

 

Pictures of the reef below:

 Conclusions:

Based on the results of the survey efforts, TISIRI believes the area located at 30° 10.353’ N, 81° 09.460’ is adequate for the future deployment of concrete artificial reef materials.

-The recommended site is within FF permitted area (Permit # SAJ-2007-261).

-No obvious signs of “live bottom” were discovered within the area surveyed and 200 feet outside the surveyed area boundaries.

-Sediment penetration suggests a relatively firm substrate base.

-Sediment analysis suggest primarily medium to large sized sand grains which implies less probability of material sinking into the substrate.

-The average depth of the site appeared to be around 72 feet based on scuba divers instrumentation.  This depth allows for over 20 feet of relief of reef materials to stay within the permit requirements of a 50 foot sea surface clearance.

 

Sediment photographs:

 

Video:

-Pre-deployment survey @ 30°10.353’N, 81°09.460’W

 

Special Thanks:

 - Divers Joe Kistel, Ed Kalakauskis, Nate Tucei, and Dane Sheilds

-Larry Davis for equipment support

-The City of Jacksonville

-The FWC

-Captain Steve Park and the Native Diver II

-Nassau Web Design

-Office Suites Plus

5 Responses

  1. tom t

    Awesome. Nice report. Looking forward to the new reef.

  2. Always a pleasure to assist.

  3. roberto

    That is awesome the three reefs will be laid out in a triangular footprint. I will be able to do all my fishing in diving in one general area. Thanks for this huge convenience and accessibility!

  4. Clara

    Will there be sea turtles?

  5. Capt Nathan Hale

    Have a third reef near two others will make my three hour tour worth it.
    My guests will enjoy the convenience.

    Thank you for doing this..

  6. […] Deployment (a different video): Click here Loading time-lapse: Click here Pre-deployment survey: Click here Near by placement: Click […]

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