Research Papers

New Data Assessing the Concentrations and Potential Toxicity of Copper in Sediments

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Bob Dwyer & Hal Stillman, Copper Alliance

Svein Midtoy, Lerow AS

Daniel Steitz, Wieland

Alex Brown, EcoSea SA

Using Life Cycle Assessment(LCA) to Measure Improvements in Salmonid Aquaculture Performance from Copper Alloy Mesh Materials

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Robert Dwyer1, Nathan Ayer2, Lise Laurin2 , Hal Stillman1

1International Copper Association, New York USA

2 EarthShiftGlobal, Kittery, ME USA

Environmental Monitoring Around an Offshore Fish Farm with Copper Alloy Mesh Pens in the Northern Aegean Sea

In the present study, environmental monitoring was undertaken around an offshore fish farm with copper alloy mesh pens located in the Northern Aegean Sea. From the water velocity results obtained at the farm site, located in the Strait of Canakkale (formerly the Dardanelles) it was recorded that the horizontal water velocity reached 36cms-1 at select times. The average water velocity was found to be 22cms-1. Water quality measurements were made over an 11 months period between September 2011 and July 2012. Other than occasional wind drawn mixing events, the two different water masses can be clearly indicated depending on the temperature and salinity values recorded throughout the study period in the Strait of Canakkale. Inorganic nutrient concentrations such as NO- 2+NO- 3, NH4, PO4, TP and SiO2, changed from low to moderate through most of the sampling period. The data for TSS varied among sampling depths between 0.06 and 10.40 mgL-1, being below the typical seawater quality measurement threshold of 30 mgL-1 pronounced by Water Pollution Control Regulations. Chlorophyll-a concentration, ranged between 0.143-2.633μgL-1, 0.055-1.519 μgL-1, and 0.110-2.288 μgL-1, at the surface, 15m, and 30m, respectively. It has been observed that starting from March 2012, especially in Stations 2 and 3, the phytoplankton abundance controlled the TSS, rather than terrestrial sources.

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Yesim Buyukates1, Barbaros Celikkol2, Murat Yigit3, *, Judson DeCew4, Musa Bulut3
1Department of Marine Biology, Faculty of Marine Science and Technology, Canakkale Onsekiz Mart University, Canakkale, Turkey

2Department of Mechanical and Ocean Engineering, University of New Hampshire, Durham, NH – USA

3Department of Aquaculture and Marine Technology, Faculty of Marine Science and Technology, Canakkale Onsekiz Mart University, Canakkale, Turkey

4Jere A. Chase Ocean Engineering Laboratory, School of Marine Science and Ocean Engineering, University of New Hampshire, Durham, NH – USA

Engineering procedures for design and analysis of submersible fishcages with copper netting for exposed marine environment

Novel design and analysis procedures are needed for engineering of the offshore fish farms utilizing copper alloy netting. Existing technologies developed for fish cages with polymer nets are not directly transferrable to the fish cages with copper netting. In particular, the structural integrity of fishcage/mooring systems, and initial high costs of fish cages with copper netting are two major concerns in the engineering for open ocean aquaculture. We propose the modified engineering procedures, which address these concerns and allow for retrofitting of existing fish farming systems with polymer nets. These procedures are illustrated by considering two case studies: design of a rigid-frame and flexible gravity-type fish cages. Performance of both designs is analyzed after the field trials in the North Atlantic and South Pacific oceans, correspondingly.

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Andrew Drach a, Igor Tsukrov a,∗, Judson DeCewb, Barbaros Celikkol a a Mechanical Engineering Department, University of New Hampshire, Durham, NH USA
b HALO Maritime Defense Systems, Inc., Newton, NH USA

EFFECT OF THE BENDING STIFFNESS ON THE VOLUMETRIC STABILITY OF FISH CAGES WITH COPPER ALLOY NETTING

It has been well established that aquaculture will supply an increasing share of the world’s seafood demand in the future. Most finfish are raised in marine fish cages consisting of a floating superstructure, polymer net chamber and a sinker weight(s). These systems are susceptible to large deformations, which can lead to reduction of the cage’s volume and severely impact the health of the fish stock.
Net chamber deformation could be mitigated with the use of stiffer netting, such as copper alloy mesh. However, little is known regarding the bending characteristics of copper alloy nets and their relationship to the volumetric deformation of a fish cage. In this study, numerical modeling tools and techniques are developed and used to predict the dynamic structural behavior of gravity fish cages with copper alloy. An analytical model is validated by experimental testing to obtain an equivalent flexural rigidity. The model is used for finite element studies of the effect of bending resistance on the volume loss of fish cages with copper alloy netting. The contribution of the copper alloy’s bending resistance to the volumetric stability is found to be minimal for the tested configurations. Thus, the traditional numerical modeling techniques (i.e. using truss elements) are sufficient for analyzing copper alloy cage configurations.

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V International Conference on Computational Methods in Marine Engineering MARINE 2013 B. Brinkmann and P. Wriggers (Eds)

JUDSON C. DECEW*, MICHAEL OSIENSKI*, ANDREW DRACH†, BARBAROS CELIKKOL†, IGOR TSUKROV†
* Center for Ocean Engineering University of New Hampshire Durham, NH 03824, USA e-mail: jud.decew@unh.edu

† Department of Mechanical Engineering University of New Hampshire Durham, NH 03824, USA e-mail: igor.tsukrov@unh.edu

Field Studies of Corrosion Behaviour of Copper Alloys in Natural Seawater

research_corrosionEight copper alloys were tested in a one-year field deployment in the North Atlantic Ocean. The corrosion behaviour was characterized by weight loss, optical and electronic microscopy analyses. The biofouling performance was quantified in terms of the biomass accumulation. The testing program included specimens in tensioned and untensioned configurations, as well as a set for seasonal deployments. The seasonal corrosion rates were 140% higher, and the rates of tensioned specimens were 39% higher than those of the untensioned specimens after 12 months of deployment. Good biofouling resistance was observed for all but one alloy, which exhibited heavy fouling by barnacles.

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Authors:
Andrew Drach (a), Igor Tsukrov (a), Judson DeCew (a), Jochen Aufrecht (b), Adolf Grohbauer (b), Uwe Hofmann (b)
(a) Mechanical Engineering Department, University of New Hampshire, Durham, NH 03824, USA
(b) Wieland-Werke AG, Ulm, Germany

Copper Alloy Mesh Pens Easily Meet Stringent Water Quality Standards for Copper in British Columbia

Researchers monitoring copper concentrations from two copper-alloy mesh (CAM) pens installed in the Fortune Channel in British Columbia (BC), found full compliance with strict BC environmental regulations. The International Copper Association worked with Mainstream Canada to install the copper alloy mesh pens in the Fortune Channel near Tofino, B.C. in November of 2012.

An aquatic chemistry team from Wilfrid Laurier University in Ontario monitored copper concentrations in the channel before, during, and after CAM pen installation, to identify any increases in copper concentrations above preexisting background levels associated with the installation. The team also monitored the potential corrosion of the CAM materials. The monitoring was required to ensure compliance with British Columbia’s marine water quality standards for copper – the most stringent in the world (2.0 ug/L total copper average and no single value higher than 3.0 ug/L).

The results of this monitoring study were presented by the Wilfrid Laurier Team at Aquaculture Canada 2013 in Guelph, Ontario in the “Innovative Technologies” session on June 3.

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The results were quite favorable. Pre-installation background copper concentrations averaged 0.3 ug/L, with a few excursions as high as 1.5 ug/l. Copper concentrations were monitored for 15 days once the installation started. Concentrations downcurrent of the pens averaged about 0.4 ug/l, with one set of samples, nine days after the installation was completed, with a maximum of 2.6 ug/L. The team concluded that all of the monitoring data demonstrated full compliance with the BC copper standards.

The Laurier team also showed that the BC copper standards were more protective than necessary. The marine Biotic Ligand Model (BLM) was used. This model estimates how much of the total copper is bioavailable (and thus potentially toxic) to aquatic organisms. The BLM was also used to predict an alternative standard based on the copper’s bioavailability to blue mussels (the most sensitive organism to copper). The BLM model’s predictions indicated that copper concentrations in these waters could be as high as 7 to 11 ug/L before being toxic to mussels and other aquatic biota (post-installation measured concentrations averaged 0.4 ug/L, up to one sample at 2.6 ug/L). Thus, the BLM predictions show that the BC standards for copper are 3-to 5-times more protective than needed for all aquatic biota in these waters.

The Copper Alliance advocates the adoption of copper bioavailability and the use of tools like the BLM to set science-based copper standards with regulatory agencies worldwide. Environment Canada is now reviewing both freshwater and marine versions of the BLM for updating its copper standards.

Prepared May 30, 2013
By: Bob Dwyer
Associate Director for Environment in the Health, Environment and Sustainable Development (HESD) Initiative
International Copper Association (ICA)

Van Diemen Aquaculture Study

There is a great deal of complexity associated with the analysis of performance of Atlantic salmon in brass nets at Van Diemen Aquaculture (VDA) and it is challenging to succinctly portray the advantages of brass nets based on VDA performance over the last six years – having said that VDA would no longer be a commercially viable Atlantic salmon farm if it were farming in netting technology other than brass nets. It is not possible to make direct comparisons with the performance of other Tasmanian salmon farming operations as there is no access to verifiable performance data from those companies, and the farming conditions at VDA differ greatly from southern Tasmania – research scientists from an international feed company have described VDA as the world’s only “hot water” salmon farm.

Brass nets were first introduced in February 2005 alongside both nylon and galvanized steel nets. They quickly demonstrated many advantages and the phase out of steel nets was completed in March 2007 with the installation of the first URX nets, however the company continues to use nylon nets inside brass nets for the initial stocking of small fish. The raw data on fish performance is available for all year classes stocked since 2002 and allows some limited fish performance analysis.

The transition to brass net technology has allowed VDA to significantly change farm management and production strategies, expand the farm in to a more physically challenging environment, and maintain adequate environmental conditions for the farming of Atlantic salmon despite external factors that on occasions are at the limits for successful culture of salmon.

Background to Van Diemen Aquaculture

Van Diemen Aquaculture P/L is a small privately owned company that farms Atlantic salmon, (Salmo salar), on a single farm site in northern Tasmania. It commenced operations in 1998 at a small trial site approximately one kilometre upstream from the existing site. Farming commenced at the current site in early 2000 with the installation of four steel cages. (See Figure 1) Since 2000 the operation has expanded from 4 to 28 cages (24*24m, volume of 6500 cubic metres per cage), increasing annual production to over 2600 tonnes. The farm is unique in the Tasmanian industry context – it utilizes a steel cage platform with a fixed link to the shoreline enabling vehicular and pedestrian access. The company does not need a fleet of boats to operate, smolt are delivered by pipe direct from shore to cage on arrival, feed is delivered from a shore based storage facility by pipeline to each cage and harvest fish are pumped ashore to a purpose built harvest facility.

Annual smolt intake of 750,000 occurs from April to August, and harvest is from June in the following year to January. Average harvest size over recent intakes has reached 4.3kg ITR (round weight). The site carries mixed year classes for 8-9 months of each year, with juvenile fish held in the relatively calmer conditions inshore, while larger production fish are held in outer farm positions in fast moving water. Van Diemen fish have a distinctive shape to help them cope with life in strong currents, characterized by a condition factor at harvest of 1.6 – 1.8; fish have strong shoulders, firm flesh and fillet recovery up to 2% greater than the Tasmanian industry average.

The annual production cycle is significantly influenced by water temperature and to a lesser degree by fluctuating salinity. Summer water temperatures generally exceed 20oC for at least some of the season, and this has a significant impact on growth potential.

To request the full report, please contact aquaculture@copperalliance.org.

Report prepared by Michael Hortle, The Aquaculture Advisor

Effect of Netting Materials on Fouling and Parasite Egg Loading on Offshore Net Pens in Hawaii

Parasitic skin flukes, primarily Capsalid Monogeneans, Benedenia sp. and Neobenedenia sp. are a scourge to the marine aquaculture industry worldwide. These parasites infect a wide range of hosts in tropical and temperate waters, causing immediate irritation and stress to the animal and, if levels are left unchecked, can lead to bacterial infections and eventual death. The life cycle and physiology of these two genera lend themselves to exponential growth in fish tanks and seacages. A series of topical chemical treatments can often remedy the problem in land-based containment systems, but topical treatments are less effective in offshore net pens.

Neobenedenia, the parasite of concern in Hawaiian offshore mariculture, reproduces by releasing (up to) several hundred eggs daily (Whittington and Horton, 1996). These eggs are composed of a rugged shell and a long tendril. The tendrils allow the eggs to attach directly to netting or to fouling on the netting. Bathing of contained fish in a chemical compound such as Hydrogen peroxide only removes the infective stage of the parasite from the skin of the fish, leaving unhatched eggs attached to the netting unharmed. These eggs will tend to hatch and re-infect the fish within the net pen. Preventing reinfection requires a significant reduction in the ability of parasite eggs to efficiently colonize the netting material. The virulence of Neobenedenia infection can be greatly reduced by identifying netting materials which inhibit the efficacy of parasite egg colonization.

Several attributes make a netting material more or less resistant to parasite egg colonization. First, is the material porous or contain areas of overlap, such as in a braided rope? The small crevices formed by the strands of a braided rope give egg attachment mechanisms greater purchase. Second, is the material easy to clean? Smooth surface netting materials tend to facilitate easier removal of eggs and fouling with active cleaning methods such as pressure washing. Third, is there an antifoulant compound coated on the netting, or is it made of a compound that has antifoulant properties that will inhibit egg attachment or health?

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Prepared July 17, 2012
By: Jennica Lowell, M.S.
Blue Ocean Mariculture