The principle objective of this project is to provide a detailed map for each of the 5 artificial reefs in the Central Basin of Lake Erie off the communities of Lorain and Lakewood, Ohio. This map will document the reef locations and characteristics. The product will be a series of maps for each reef which will have the following information: - A location map. - A plan view of the reef area made from a side scan sonar mosaic to produce an electronic image of the lake bottom in detailed resolution. - A Latitude/Longitude grid overlay which will provide accuracy to .02' ( 2 hundredths of a minute). - A bathymetry contour map. ? A sediment substrate map overlay showing all sediments on the surface. Sub bottom seismic data will also be provided which will aid in determination of sediment types and foundation of existing material. Two sets of maps may be produced from this data; one for general use containing location and bottom surface resolution and one for more detailed needs incorporating the bathymetry and geologic substrate information.

The product of this grant (described in objectives) may be used to provide information of the artificial reef areas that can be used as a guide for scientists and researchers to document the effectiveness of the reefs and to show the reef characteristics such as configuration, texture and geologic composition which are not currently available. The information will also be a valuable tool used by fishermen and recreational divers.

The five reefs to be investigated include 2 off Lorain and 3 off Lakewood. The side scan sonar system to be used is the Division-owned Klein dual frequency 595 system with a Triton Elics ISIS data acquisition system which will acquire, digitize and mosaic the data. Data will be collected using the Ohio Geological Survey's research vessels "GS-1" and "GS-3". The "GS-1" will be used to collect the basic side scan and seismic data and the "GS-3" will be used for ground truthing and additional side scan sonar data. The detailed side scan data will be acquired at a 75 meter scale, 150 meter swath width with track lines spaced on a grid to provide a 50% overlap of data. Geo-referencing of the data will be accomplished in real time by input from a Trimble NT200D Differential Global Positioning System onboard each vessel into the Triton ISIS data acquisition system. Shallow sub-bottom seismic will be collected to provide a perspective of the foundation composition and to aid in interpretation. Bathymetric data will also be collected in a separate survey over each reef and contoured through Spectra Precision contouring software or equivalent.

The Triton ISIS system will allow post processing the data into a geo-referenced mosaic which will form the base map of each reef. The data will be analyzed for quality by staff of the Lake Erie Geology Group under the direction of Dr. Mackey. After initial interpretation, ground truthing and verification will begin by selection of specific locations that will require further inspection. Most ground truth activities employ the use of the Division-owned underwater towed video camera, coring and grab sampling devices. The research vessel "GS-3" will be used for this portion of the project due to the vessels faster speed and ability to be trailered to the work site. Ground truthing is more time consuming than the original electronic data acquisition. The quantity of time spent in the field for ground truthing will depend on complexity of original data acquisition and the corresponding ability to map the reflectivity of the material.

After ground truthing, the reef mosaics will be imported into ©ArcView GIS software where the corrected bathymetry contours and geologic sediment substrate maps will be layered Reproduction and distribution of the data is not a part of this proposal.

During August and October of 2000, the Ohio Department of Natural Resources, Division of Geological Survey employed the division's 25-foot research vessel, R/V GS-3, to make side scan sonar surveys of 8 artificial reefs that have been built in the Central Basin area of the Ohio portion of Lake Erie. The project was requested by the Ohio Sea Grant Program and the goal was to use sidescan sonar to map and verify the locations, characterize the area settings, and produce detailed descriptions of each of the artificial reefs. To accomplish this task, overall views of each of three reef areas were made first. These maps were used to verify each of the individual reef's location, get an over all setting for each reef complex, and make sure that all the parts of the reefs were located. These maps are at 20-centimeter resolution and 1:10,000 scale. Area substrate characteristics were added to give a regional setting perspective for each reef area. Once each reef was located and identified, a detailed set of maps were then produced of each individual reef at 10 centimeter resolution at varying scales to provide better detail. These digitally geo-referenced maps will provide a visual representation of each reef that will be useful for recreational users including fishermen and scuba divers. In addition, the maps can be used as diagrams for researchers to plan research and as base maps on which to present data when evaluating the effectiveness and other characteristics of the reefs.

 

Numerous Ohio Sea Grant publications document the construction history of each of these reefs. The first set of reefs to be constructed were demonstration projects built offshore of both Lorain and Lakewood Ohio. At each location multiple reef mounds were built within a general area. The second set of reefs was built using concrete rubble from the destruction of the old Cleveland Stadium. Two reefs were built on the west side of Cleveland, near the Perkins Beach area of Edgewater State Park and a single reef was built on the east side of Cleveland near Wildwood Park.

Sidescan sonar operates on the principle that sound impulses transmitted underwater produce echoes or reflections from objects and materials on the bottom of the lake, which vary in intensity based, in large part, on the density of the material. This varying of intensity produces light and dark areas on the record called backscatter. The side scan system uses the return from transmitted sound pulses to produce a continuous acoustic backscatter record of the lake bottom along the survey trackline. The side scan records were collected with navigation data and digitized in the field using a Triton Elics Data Acquisition system, then post-processed in the office to geo-reference each record, correct for distortion and assemble side-by-side into a mosaic. These side scan mosaics were then imported into Arcview© Geographic Information System software. Physical and visual sample data were then used to assign physical characteristics to areas of similar backscatter on the mosaiced maps to describe substrates on the bottom surface. The GIS software projects the mosaics as a map is projected and provides a layout which allows attributes and latitude/longitude lines to be added. The resulting image/map produced are reasonably accurate and provide a graphic view of the reef. On these maps, the relief of objects can be interpreted by looking at the shape of the acoustic shadow produced by the object. Similar to a light shadow, the longer the shadow the higher the object protrudes from the surrounding surface at a given distance and angle from the transducer (sound source and receiver). Details of the top and front surfaces can be seen in the patterns of light and dark on the mosaicked record. On these records the light areas are areas where relatively more sound is returned to the sidescan sonar transducer and dark areas are where little to no sound was returned.

Equipment used on the project included a dual frequency Klein 595© system and a Triton Elics Data Acquisition System© for acquiring and processing the records. The Differential Geographic Positioning System was employed for navigation utilizing a Trimble DSM-212H DGPS receiver which is capable of receiving updates at 10 Hz (10 times per second). Due to the close proximity of the track lines, Trimble HydroPro Hydrographic Survey software employed on a laptop received the DGPS signals and calculated the offset and layback distances between the side scan transducer and the DGPS antenna. A computerized Raytheon autopilot was also utilized on this project to provide minimal movement of the boat, straight track lines in a very tight survey pattern and removed the need for another person to steer. Both 100 and 500 kHz frequencies from the Klein 595© system were recorded but only the more detailed 500 kHz records were used to construct all mosaics. At each reef complex the first sidescan traverses were made using the 150-meter range. This records the acoustic bottom characteristics out to 150 meters from each side of the transducer.

During the field visit, a second set of closely spaced traverses over each individual artificial reef location was made using the 75-meter range. The shorter range was selected to provide detailed records that would be used to characterize each particular artificial reef.

There are two reefs listed off of Lorain as part of the Lorain artificial reef complex. The nearshore reef is the "Polish Fisherman's Club Reef" and was built about 1 mile west of Lorain Harbor, about half mile offshore. It is a series of dump mounds in a serpentine form that provide relief on a nearly featureless bottom. The dump mounds generally range in height from about 3 feet to 6 feet. The other artificial reef in this complex is "Mountain Reef". It is about 300 feet north of the Polish Fisherman's Club Reef. Mountain Reef is a straight-line pile with a tall mound at the west end. Continuing to the west are a couple of low dump mounds offset toward the north and then a couple of more low mounds that are back in line with the main part of Mountain Reef. The height of crest of the main reef ranges from about 9 feet near the west end to 3 feet at the east end. Between Polish Fisherman's Club Reef and Mountain Reef are two low dump mounds that were described as dump mistakes when the reefs were being constructed. All of these artificial reefs are very close together and they have all been placed on a hard clay surface that has cobbles and sandy areas. Inshore from the reefs is a poorly defined outcrop of bedrock (probably shale). Offshore and to the east of the reefs are a couple of narrow bands of muddy sand.

The Lakewood artificial reef complex includes the "Cuyahoga County Commissioners Reef" (CCC). It is about half mile offshore and about 2.6 miles east-northeast of the Rocky River Breakwater light. In the same area are the "Little Test Reef", about 1300 feet to the west-northwest, and the "Big Test Reef", about 1000 feet to the east-northeast of the Cuyahoga County Commissioners Reef. Another dumpsite was possible, "Bratton's Barge Reef", but it was not defined as a specific site and is probably included in the Cuyahoga County Commissioners Reef site. The Cuyahoga County Commissioners Reef is a curving series of continuous and discontinuous dump mounds of varying heights (range from 6 to 10 feet) that have been placed on a bedrock (shale) outcrop. Little Test Reef is made up of 6 low dump mounds (about 3 feet in height) that are about 30 to 40 feet in diameter which rest on a muddy bottom, less than 500 feet north of the edge of the bedrock outcrop. Big Test Reef is a group of four low mounds (about 5 feet in height) that are about 40 to 50 feet in diameter, these are also sited on the mud bottom and are also less than 500 feet north of the edge of the bedrock outcrop.

Artificial Reef General Mid Points of Area or Main Feature
Reef	Latitude	Longitude	Easting	Northing
Stadium East	41° 35' 55.785475" N	81° 33' 48.682088" W	453038.31000	4605389.59000
Stadium West #2	41° 29' 58.087320" N	81° 45' 24.552960" W	436832.94000	4594481.68000
Stadium West #1	41° 30' 08.748858" N	81° 45' 35.514123" W	436581.70000	4594812.70000
Big Test Reef	41° 30' 15.146696" N	81° 47' 03.172584" W	434551.26000	4595028.15000
Little Test Reef	41° 30' 16.365287" N	81° 47' 32.032438" W	433882.55000	4595071.83000
Cuyahoga County Commissioners	41° 30' 10.688341" N	81° 47' 15.184795" W	434271.53000	4594893.19000
Lorain Mountain Reef	41° 28' 08.912933" N	82° 12' 44.971266" W	398753.09000	4591547.94000
Lorain Polish Fishermans Club	41° 28' 05.049949" N	82° 12' 43.223573" W	398791.96000	4591428.24000

Lakewood and Stadium West Artificial Reef Complex, Overall View	View
Lorain Artificial Reef Complex, Overall View	View
Lakewood and Stadium West Artificial Reef Complex, Big Test Reef	View
Lakewood and Stadium West Artificial Reef Complex, Cuyahoga County Commissioners Reef	View
Lakewood and Stadium West Artificial Reef Complex, Little Test Reef	View
Lorain Artificial Reef Complex, Mountain Reef (upper) and Polish Fisherman's Club Reef (lower)	View