Artificial Reef Project Final Report

 

 

 

 

 

 

 

Ocean Habitat Restoration Pilot Project

 

New Campbellton, NS

 

 

 

 

 

Shelley Porter, M.Sc. and Donald MacQueen, M.A.Sc.

 

ACAP – Cape Breton

582 George St., Sydney

Nova Scotia

November, 2004

Table Of Contents

 

 

Table Of Contents.. 2

Introduction.. 3

Study Site. 5

Methods.. 6

Module Deployment.. 10

Placing of Permanent Mooring: 11

Dive Reports.. 12

Results.. 14

Discussion.. 15

Recommendations.. 16

Literature and Official Web pages Cited.. 17

Personal Communications.. 17

 

 

Table of Figures/Photos

 

 

Figure 1: Kelly Cove 5

Figure 2: Reef Ball Mold Bases. 6

Figure 3: Rob Duke - Reef Innovations. 6

Figure 4: Two Bay & Two Pallet Ball Molds. 7

Figure 5: Application of Sugar Water Release Agent.. 8

Figure 6: Top View of Bay Mold Prior to Inflation of Polyform Buoy.. 8

Figure 7: Top View of Freshly Poured Mold.. 9

Figure 8: Completed Module, Showing Surface Texture. 9

Figure 9: loading Reef Ball Modules at Municipal Ready Mix.. 10

Figure 10: Three Bay Balls at Stern of Deployment Vessel. 11

Figure 11: Neil MacKinnon of ScubaTech Ltd Preparing for Check Dive. 11

 

 

 

 

 

 

 

 

 

 

Introduction

 

The Bras d'Or Lakes marine fish and invertebrate species communities are at risk due to increased pressure from recreational (boating, etc.) and commercial (fishing, aquaculture) activities.  Eskasoni Fish and Wildlife has expressed concern about threats to the small lobster stock in the Lakes (Lamont et al, 2003), and the possibility of enhancement of lobster habitat.  Due to its geological structure, some areas of the Bras d'Or Lakes' bottom have limited substrate for attachment and colonization by early successional-stage community-building species.  Artificial substrate can increase attachment and colonization opportunities, subsequently increasing nutrients and habitat for species such as lobster, oysters, and finfish. The increase in species' numbers resulting from the creation of new habitat would provide a reserve of individuals able to rebuild populations following contamination (sewage, shellfish contaminants) or physical disturbances in other areas of the lake.

 

Damage to marine fish and invertebrate habitat decreases species populations, affecting local and broad economies and community stability.  Apart from cleaning up pollutants such as oil, little has been done to restore damaged substrate.  The technology to restore degraded substrates exists, in the form of artificial reefs.  Artificial reefs have been deployed in many areas of the world, to either enhance or restore marine habitat, with minimal (and short-term) negative impact, and great success.

 

A concrete artificial reef was installed at New Campbellton, offshore from an area previously used as a loading dock for limestone quarried locally.  This site is an easily accessible shore dive, and the area is already well-known to local divers.  Observations (Hearn, pers. comm.; pers. obs.) in the area indicate that organisms such as lobsters (Homarus americanus), Rock Crab (Cancer irroratus), and scallops (Plactopectes magellanicus) use any substrate (natural and human-built rock formations, metal pier supports) available for attachment and shelter.  Apart from the pier and rocks placed as a berm to support the roadway, no substrate is available in the area.  This site is ideal for monitoring colonization of the artificial reef, as organisms found on and around it would have been drawn to it as dispersers, not simply have moved from adjacent already-existing colonies.  This colonization from non-existent habitat to artificial habitat will give a clear indication of how such artificial habitat may be colonized following a catastrophic disturbance.

 

Concrete is an inert material with no risk of contaminating the surrounding waters.  Concrete closely resembles natural stone, and its texture is preferred over metal or rubber (tires) for attachment of sessile marine organisms.  The perforated, hollow design of the reef provides shelter for fish and motile invertebrates.  The techniques for constructing and deploying these reef ball modules are well-tested internationally, and easily transferable to any area in need of remediation or habitat enhancement.  This pilot project will stand as a test and demonstration site, with results comparable to and easily examined by other communities or agencies in the region.

This reef ball installation provides surface area for attachment of sessile marine organisms equivalent to 62m2; the hollow reef ball structures also provide shelter for fish and invertebrates (e.g. lobster) with total numbers affected relative to the size and social behaviour of the individuals.  The site has been subject to prior disturbance related to construction of a loading pier, the loading of gypsum barges (with associated rock debris), and reinforcement of the roadbed and pier with rock berms.

 


 

Study Site

 

The site was chosen because it was subject to human disturbance historically, is actively used by local dive masters as a training site, and for its potential for building local capacity for 1) knowledge of reef colonization under local conditions and 2) reef installation and volunteer monitoring expertise.  The reef site is located at 46 17.250N; 60 26.435W, 75 metres directly east offshore from Bluenose Point.  The bottom is flat, silty, and barren, variously described by local divers and fishermen as “a desert”.  The area immediately adjacent to the road and the pilings of the loading pier are fished for lobster, but no other fishing activity takes place here, as there are no species of commercial value.

 

Figure 1: Kelly Cove

 

 

 

Methods

 

Reef Ball Module Casting:

The bases for the reef ball molds were built by ACAP-CB and CEIP staff at the CEIP workshop. Two sizes of bases were produced: 4’x4’ for the bay ball molds and 5’6”x5’6” for the pallet ball molds. Two bases were constructed for each mold to allow for a longer curing period for each module prior to removal of the casting from the base. The bases were delivered to be set up at the Municipal Ready-Mix facility in Sydney River on September 28, 2004.  The trainer from Reef Ball Foundation, Bradenton, FL, USA, Robbie Duke, arrived September 29, 2004.

 

 

Figure 2: Reef Ball Mold Bases

 

 

 

Figure 3: Rob Duke - Reef Innovations

 

 

 

 

Manufacture of the reef ball modules (hereafter referred to as “modules”) was as according to the Reef Ball Mold Systems Training Manual (Reef Ball Development Group Ltd., 1995/1996) (attached), with the following amendments:

 

1)     the mold bases were not trimmed to form circles, as the extra material was required for the correct positioning of the hold-down plates for the molds;

2)     used a combination of “3/4 inch” and “3/8 inch” stone for aggregate in the concrete mix, based on availability;  the former is the industry standard; the latter was not readily obtainable.

3)     used 2.5 cm. diameter PVC tubing as spacers (colloquially referred to as “chickens”) to ensure proper concrete thickness in the bay ball molds;

4)     a Calcium Chloride accelerant was used to compensate for cold ambient temperature conditions during the first day of casting.   

 

 

Casting of the modules began September 30, 2004.  Four ACAP-CB staff, one ACAP-CB environmental intern, one Reefball Foundation trainer, and various staff from Municipal Ready-Mix were involved with the casting.  Staff from Municipal Ready-Mix provided technical and practical expertise, including proper cement to aggregate/water/additive mixtures.  The concrete was a standard medium-strength mixture, to which was added Advaflow (plasticizer), microsilica, and fibreglas reinforcing fibre.  These additives are recommended to improve the flowability of the concrete, to increase the concrete’s strength, to lower the concrete’s pH, and to improve durability of the modules (with these additives, the life expectancy of a module is 500 years). 

 

 

Figure 4: Two Bay & Two Pallet Ball Molds

 

 

 

 

 

 

Figure 5: Application of Sugar Water Release Agent

 

The interior of each mold was coated with sugar-water, to inhibit the hardening of the outermost layer of concrete; when the mold is removed, this soft outer layer is washed away to expose the aggregate, creating the desired rough surface texture.

 

 

Figure 6: Top View of Bay Mold Prior to Inflation of Polyform Buoy

 

 

 

 

 

 

 

Figure 7: Top View of Freshly Poured Mold

 

 

Figure 8: Completed Module, Showing Surface Texture

 

 

 


 

Module Deployment:

The modules were removed from Municipal Ready Mix, Sydney River, site via boom truck and transported to the shore at New Campbellton. The modules were removed from the boom truck individually, and placed on the beach; after this point, operations were assumed by ScubaTech Ltd. divers and boat crew.   The boat used for this operation was a 13.8 metre commercial scallop dragging vessel, Canadian Coast Guard certified for placing concrete buoys weighing up to 3 tonnes. The individual modules were winched aboard the boat, maximum boatload being two bay balls and one pallet ball.  The target locations were marked with buoys, using the map as per permit requirements. The modules were transported to their target locations on board the boat, then winched over the side and guided into position by ScubaTech commercial SCUBA divers in the water.  Underwater video footage of this process was filmed during the installation.  Each module was checked following release from the winch, to ensure proper positioning.  Some modules landed on their sides or tops, but were easily rolled into position by the divers.

 

 

Figure 9: Loading Reef Ball Modules at Municipal Ready Mix

 

 

Figure 10: Three Bay Balls at Stern of Deployment Vessel

 

 

 

 

Figure 11: Neil MacKinnon of ScubaTech Ltd Preparing for Check Dive

 

All markers and buoys were cleared from the area once the modules   were in place and the area was left for a week to allow the disturbed sediments to settle.  A “check” dive and attempted survey were done October 28, 2004 (see dive reports, above).

 

 

Placing of Permanent Mooring:

A permanent mooring consisting of a 1.2 x 0.15 metre diameter pulley wheel weighing approximately 450 kg. was placed at the eastern end of the reef ball field.  The wheel had been previously cleaned, and contained no bearings, grease or oil.  A polyform buoy was attached to the mooring with a rope.

Dive Reports:

August 19, 2004

(Shore dive)

Conditions: air temperature, 24o C; bottom temperature, 19o C; maximum depth, 10.1m; visibility, 5m.

The purpose of this dive was to take photos of the substrate, and place a small concrete marker at the study site.  Marine species observed were: Rock Crab (Cancer irroratus); Cunner (Tautogolabrus adspersus) and Northern Lobster (Homarus americanus).  A concrete marker was placed at the 81 metre point from shore; this is intended to help divers locate the reef ball field.

 

October 14, 2004

(Shore dive)

Dive One Conditions: air temperature, 15o C; bottom temperature, 12o C; max. depth,10.2m; visibility, 2m.

The purpose of this dive was to locate the rock cairn and move it 150 metres further offshore, in accordance to recently acquired permitting information.

The divers swam a 100m line from the shoreline to the initial study site. Two (2) Rock Crabs (Cancer irroratus); one (1) lobster (Homarus americanus) under the rock cairn; one (1) flounder (Pleuronectes americanus), (approx. 30 cm in length) were observed.  It was noted that the silt around the cairn had eroded somewhat, leaving an approx. 15 cm deep by 10 cm wide trench around the structure.  A large lobster had taken up residence under the cairn.  Five Sea Perch (Tautogolabrus adspersus) varying in size from 2.5 to 6 cm., were swimming amongst the Laminaria sp. (small pieces of which had been attached to one of the rocks we placed in the cairn).

 

October 14, 2004

(Shore dive)

Dive Two Conditions: air temperature, 18oC; bottom temperature,12oC; maximum depth, 9.8m; visibility, 2m.

The divers swam a 250m line to the centre of the final reef site.  They observed one (1) Sea Star (Asterias vulgaris); two (2) small (3 and 5 cm diameter) Deep Sea Scallops (Plactopectes magellanicus); and a 30 cm diameter clump of Cordweed (Chorda filum).  The bottom is scattered with clam and limpet shells; rarely a market-size scallop shell is noted.

 

The bottom in this entire area is flat, silty, and barren; broken pieces of oarweed and cordweed are observed floating in the current. At the tide change, a strong northwest current was noted but we were unable to measure its intensity. A marker buoy (cotton cloth bag of bricks anchoring a plastic 4 litre water jug, attached with cotton line) was left at the middle of the reef site as a guide for placement of the reef modules.  No transect markers were placed, as these would likely be destroyed upon placement of the modules.  Transect markers were to be placed during the survey dive following installation.

 

October 28, 2004

(Boat dive)

Conditions: air temperature, 7oC; water temperature, 11oC; maximum depth, 10.1m; visibility, 4m.

A local lobster fisherman’s boat was volunteered for this dive, in order to cut down on time spent swimming from shore to the reef, and to use GPS to locate the reef, thus reducing time spent searching for the modules.   However, a strong current and high wind conditions made it necessary to tie the boat to the loading pier near shore, as the boat was dragging its anchor.  The GPS location of the reef centre was marked with a rope, and divers swam from the tied boat to the rope.  Once on bottom a search began for the modules. Visibility was very poor. Four modules were located, all containing at least one Rock Crab.  Three Rock Crab were noted on one “pallet ball”.  One lobster was observed walking across the silt bottom, approximately 4 metres outside the northeastern perimeter of the reef.  A small number of Sea Perch were noted briefly inside one of the modules, but water/silt movements and varying visibility made it impossible to count them.

 

After 30 minutes of searching in conditions of severe cold and poor visibility with very little success, it was decided to end the dive.  It was concluded by the divers assembled that for future surveys, each module must be marked with an identification tag, and that the transect points be given a permanent underwater marker.  This will facilitate locating the modules even in conditions of poor visibility, and save diver time and confusion.

 


Results

 

ACAP-CB has four reef ball module molds: two “pallet” ball (1.22 x 0.88 meters, 700kilograms), and two “bay” ball (0.91 x 0.61 meters, 170 kilograms), and all additional tools and materials required to construct modules at any site.  Four ACAP-CB staff are trained to construct the modules, and capable of training others.

 

Six pallet balls and six bay balls are now positioned, in U-formation, at GPS 46.17.250N; 60.26.435W in Kelly’s Cove at New Campbellton.  This site includes a permanent mooring on the eastern perimeter of the formation. (See diagram, attached).

 

A roster of eight volunteer divers has been established, several with commercial diving experience.  Due to delays with construction and deployment of the modules, and conflicts with Nervous Wrecks meeting scheduling, volunteer training will not take place until Dec. 8.  A two hour introduction to underwater surveying and species identification will take place on that date.  This session will be repeated in May 2005, as a refresher for present participants and introduction for new volunteers.

 


Discussion

 

Many delays were experienced during this very short project.  Shipment of the reef ball molds was delayed by one month due to hurricanes in Florida while our order was being processed; the arrival of the module construction trainer was also delayed for this reason.  Concurrent delays were experienced during the permitting process with Navigable Waters and the Nova Scotia Department of Natural Resources.  Weather conditions at the time of module curing and on the originally scheduled date of deployment resulted in added delays in the installation of the reef.

 

ACAP-CB now has the materials and expertise to construct and deploy reef ball modules at any site.  ACAP-CB is unique in this capacity: no other organization within the Maritimes possesses reef ball module molds, nor does any organization in Atlantic Canada have similar size molds - the Newfoundland and Labrador government has “oyster” ball molds, intended for lobster habitat enhancement only; these modules are smaller and more limited in usefulness (aimed at very specific species) than those belonging to ACAP-CB.  With these tools and several trained staff, ACAP-CB has the capacity to assist any organization with marine habitat enhancement and remediation projects where this technology is appropriate.  Assistance will be available to government, community, fishermen’s, and environmental groups.

 

The preliminary dive surveys indicate that the modules are attractive to both fish and crustacean species.  Observations of other artificial habitat (sunken boats, our rock cairn, etc.) indicate that micro-organisms and sessile marine species colonize substrate within two to six months (Hearn, pers.comm.; Jardine, pers.comm.).  The growth of algae on the concrete marker, which took place over a period of less than one month, would make us optimistic that colonization of the modules will occur, and that the reef has high potential to become a productive area for many marine species.  When the permanent mooring was installed, a market-size lobster exhibiting territorial behaviour was noted ensconced in one of the bottom holes of the bay ball nearest the mooring, complete with gravel consistent with the building of a “nest site”.

 

The artificial reef will be a recreational dive destination, contributing to local tourism and related business, and an environmental education tool for local and visiting divers.  This type of enhancement of recreational potential for the lakes is of much lower ecological impact than such projects as boat launches and other onshore development, which disturb or even destroy marine species habitat.  The reef is maintenance free once installed.  SCUBA diving is environmentally a low-impact sport: at this type of site, divers come to view the marine life and leave it undisturbed.

 

The dive surveys were not as comprehensive as originally planned.  The delays mentioned above resulted in dives being conducted late in the season, after the onset of cold, inclement Autumn weather.  Poor visibility and cold water made the individual modules difficult to locate, and the surveys taxing for volunteers.  In subsequent years, official surveys will be shifted to the summer season; individual modules will be marked and numbered by volunteer efforts this Autumn, and a guide rope strung amongst the modules to make them easier to locate.

 

Very few species were observed; this was not considered unusual nor unexpected by the experienced divers and fishermen in the area (Hearn, Newcombe, Jardine, Fraser, Hendrickson pers. comm.). Subsequent surveys (casual spot surveys by club divers as well as official annual surveys) will be compiled to note any changes in species numbers or distribution.

 

Recommendations

 

The material to be used for “chickens” should be specified – the directions in the manual are unclear and led to confusion on the day of casting.  Differences in commercial measurements for materials in Canada vs. the USA should be taken into account: the true thickness of plywood specified in the manual differed from what was available in our region.  The wood had to be thinned to enable the mold hold-down brackets for fit properly. A barge deployment with a boom is probably the best option for this region, as there are few sand beaches.

 

In order to facilitate data collection by divers in this region, each module should be numbered and tagged before deployment. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Literature and Official Web pages Cited

 

Lamont, S.; Keefe, J.; and J. Naug. 2003. Draft Proceedings of the Bras d'Or Lakes 2003 Workshop. Wagmatcook. 64 pp.

 

Reef Ball Foundation, 2004 http://www.reefball.org/

 

Personal Communications

 

Fraser, Lloyd; Big Bras d’Or Fishermen’s Association member and Commercial Lobster licence holder, Big Bras d’Or, 2004

 

Hearn, William; President, Nervous Wrecks Dive Club, 2004

 

Hendrickson, Paul; Commercial Scallop and Lobster licence holder, Big Bras d’Or, 2004.

 

Jardine, Ken; Owner and Operator, ScubaTech Ltd., 2004

 

Newcombe, Ron, Dive Instructor/Commercial Diver/Nervous Wrecks member, 2004.