 |
||||||||||
 |
|
|
|
|
||||||
|
|
|
|
|
||||||
|
|
|
|
|||||||
|
|
|
|
|||||||
|
|
||||||||||
Science Information By:
A SCIENTIFIC REVIEW OF THE POTENTIAL ENVIRONMENTAL EFFECTS OF AQUACULTURE IN AQUATIC ECOSYSTEMS - VOLUME 1
CHEMICAL USE IN MARINE FINFISH AQUACULTURE IN CANADA: A REVIEW OF CURRENT PRACTICES AND POSSIBLE ENVIRONMENTAL EFFECTS
L.E. Burridge
Marine Environmental Sciences, Fisheries and Oceans Canada
St. Andrews Biological Station, St. Andrews, New Brunswick
EXECUTIVE SUMMARY
There has been a great deal of scientific debate regarding the environmental consequences of chemical usage in aquaculture. The debate has also moved into the public domain: where views of the opposing sides are typified by several highly publicized anti-aquaculture articles and, most recently, television documentaries (Ellis 1996; Goldburg and Triplett 1997; Milewski et al. 1997), and the responses to these articles from the finfish aquaculture industry (e.g. Canadian Aquaculture Industry Alliance 2001a,b).
Scientific reviews of the subject have been prepared by Zitko (1994) and GESAMP (1997). Issues raised and recommendations made by these authors have yet to be addressed in a significant manner. In addition, the authors of recent reviews of environmental impacts of aquaculture have identified chemical inputs from aquaculture activity as an area requiring further research (Nash 2001; Anonymous 2002). Several projects recently funded by Fisheries and Oceans Canada’s (DFO) Environmental Science Strategic Research Fund (ESSRF) have allowed scientists to begin to address some of these topics. However, these projects are still in the early stages of identifying sources of contamination and potential effects on the environment, particularly to non-target species.
This review is a summary of potential sources of chemical contamination, chemicals that may be involved and knowledge about the potential effects of these compounds. Each identified class of chemical contaminants could be the subject of its own comprehensive review. Pesticides, drugs, persistent organic pollutants and metals are discussed in the context of the Canadian aquaculture industry.
Two classes of compounds will not require further research. Food additives include antioxidants (preservatives) and carotenoid pigments (flesh coloring) and are unlikely to cause any effects in the environment. MS-222 (tricaine methanesulfonate) is used in the New Brunswick aquaculture industry, and no adverse environmental effects are foreseen with its use (Zitko 1994).
Chemicals used in the Canadian aquaculture industry are identified in Table 1. The table summarizes recent scientific information regarding their use, persistence and potential effects in the environment. There are relatively few publications in the primary literature regarding the environmental fate and effects of chemicals used in aquaculture in Canada. It is clear that a number of gaps in knowledge exist for each compound or class of compound. A more thorough review of each compound would identify further specific gaps related to that chemical.
For antibiotics, there appears to be no published data collected around Canadian aquaculture sites regarding the following: presence of antibiotics in sediments and aquatic biota; presence and prevalence of antibiotic-resistant organisms in sediments and indigenous species; or antibiotic residues in fish and non-target aquatic organisms. Accumulation of antibiotics in sediments may interfere with bacterial communities and affect mineralization of organic wastes (Stewart 1994), but no studies have been published in Canada.
Most work on pesticides to date has been conducted in the laboratory and has focused on determining the acute responses of aquatic organisms (non-target species) to exposure(s) to anti-sea lice chemicals. Limited field trials have focused on lethality of single treatments. Short-term responses to pesticide applications and long-term studies to establish the natural variability in local populations and measures of change in biodiversity need evaluation. Currently, commercially important non-target species have attracted much of the attention regarding effects of chemicals. There are apparently no data regarding the effects of these chemicals on microorganisms and planktonic species that form the foundation of the marine food chain in the near-shore environment. The chemical formulations of pesticide and disinfectant products have not been determined, and many of the 'inert' ingredients may be toxic to aquatic biota (Zitko 1994).
Little is known about the relationship between aquaculture and environmental contaminants, such as persistent organic pollutants (POPs) and metals. Feeds may be a source of contaminants to farmed fish. Knowledge of the constituents of each formulation is required for an accurate assessment of potential risk. Metals may be deposited near aquaculture sites from at least two other sources: leaching from metal cage structures and antifoulant paints. Chlorinated compounds (Hellou et al. 2000) and metal concentrations (Chou et al. 2002) were found to be higher when the total organic carbon content was high in sediments. Wooden cages with styrofoam floats may be a source of plastic contaminants (Zitko 1994). However, little known is known about the effects of plastics on aquatic organisms.
In addition, generic gaps can be identified in relation to the scientific approach and methodology:
- Chemical-related research is needed in all areas where marine finfish aquaculture is practiced in Canada. Research needs to be continued in New Brunswick, where scientists have a considerable database upon which to build and have the best opportunity to monitor long-term trends. In addition, work needs to be expanded in Newfoundland, Nova Scotia and British Columbia, where little such work has been conducted.
- Toxicity data are limited to lethality tests conducted over short time frames (e.g. 24, 48 and 96 h). More work is required to determine chronic lethal and sublethal effects and the effects of realistic exposures of these compounds on indigenous species.
- While there are laboratory-derived data on many compounds, there is almost no information regarding effects of chemicals of aquaculture origin in the field. Field surveys and experiments that investigate short-term responses to chemical application as well as long-term studies to establish natural variability in local populations and measure changes in biodiversity (and other indicators of environmental health) are needed.
- Toxicity testing relies on single species and single compound testing in the laboratory. There is a serious lack of data regarding the cumulative effect of exposure to chemicals and the concentration and fate of chemicals of aquaculture origin. The cumulative impact of chemicals and impact of multiple exposures to non-target organisms need to be determined.
Table 1. A Summary of Chemical Compounds Used in the Canadian Aquaculture Industry**
Chemical |
Use |
Persistence in Sediment |
Bioaccumulation |
Potential Effects |
Oxytetracycline |
Antibiotic |
Persistent for long periods depending on environmental factors (Björklund et al. 1990; Samuelsen 1994; Hektoen et al. 1995; Capone et al. 1996); Half-life 419 days under stagnant, anoxic conditions (Björklund et al. 1990) |
Uptake by oysters and crabs either in the laboratory or in close proximity to salmon cage sites (DFO 1997); Concentration in tissues of rock crabs over US FDA limit (Capone et al. 1996) |
Resistance to oxytetracycline may occur in fish, non-target organisms and bacterial community near aquaculture sites (Björklund et al 1991; Hansen et al. 1993; Hirvelä-Koski et al. 1994) |
| Tribrissen |
Antibiotic |
Estimated half-life of 90 days at 6-7 cm deep (Hektoen et al. 1995) |
||
| Romet 30 |
Antibiotic |
Uptake by oysters (Jones 1990; LeBris et al. 1995; Capone et al. 1996; Cross unpublished data) |
||
| Florfenicol |
Antibiotic |
Estimated half-life of 4.5 days (Hektoen et al. 1995) |
||
| Teflubenzuron |
Drug; In-feed sea lice control |
Solubility 19 mg·L-1 with a log Kowa of 4.3, indicating a potential to persist (Tomlin 1997); Persistence >6 months in area <100 m from treated cage (SEPA 1999b) |
Chitin formation inhibitor; Juvenile lobster mortalities reported (SEPA 1999b); Mitigation possible by depuration prior to molting (McHenery 1997; SEPA 1999b) |
|
| Emamectin benzoate |
Drug; In-feed sea lice control |
Solubility 5.5 mg·L-1 with log Kow of 5, indicating potential to persist (SEPA 1999b) |
Withdrawal period of 25 days prior to marketing salmon |
Chloride ion movement disruptor (Roy et al. 2000); Lethal to lobsters at 735 mg·kg-1 of food (Burridge et al. 2002); Induces molting in lobsters (Waddy et al. 2000c) |
| Ivermectin |
Drug; In-feed 'off-label' treatment for sea lice control |
Solubility of 4 mg·L-1 (Tomlin 1997); Could persist for 28 days (Wislocki et al. 1989; Roth et al. 1993) |
Withdrawal period of 180 days prior to marketing; Accumulated in lobster tissue over 10 days (Burridge, Haya and Zitko unpublished data) |
Chloride ion movement disruptor (Roy et al. 2000); Cumulative 80% Atlantic salmon mortality to 0.2 mg·kg-1 for 27 days (Johnson et al. 1993); 96h LC50 at 8.5 mg·kg-1 food for shrimp; NOECb was 2.6 mg·kg-1 food (Burridge and Haya 1993) |
| Azamethiphos |
Pesticide; Bath treatment for sea lice control |
Solubility 1.1 mg·L-1 with a log Kow of 1.05, not expected to persist (Tomlin 1997) |
Unlikely to accumulate in tissues (Roth et al. 1993, 1996) |
Neurotoxin, acetylcholinesterase (AChE) inhibitor, but not cumulative (Roth et al. 1993, 1996); Mutagenic in vitro (Committee for Veterinary Medicinal Products 1999; Zitko 2001); 1-h bath at 1 mg·L-1: lethal to 15% salmon after 24 h (Sievers et al. 1995); Larval/adult lobster 48-h LC50 at 3.57-1.39 μg·L-1 /NOEC 120 min at 1 μg·L-1 (Burridge et al. 1999a, 2000a); Behavioral responses at >10 μg·L-1 (Burridge et al. 2000a,b) |
| Copper-based antifouling paints |
Antifoulant; Reduce fouling biota on nets |
Elevated copper (Cu) reported in sediments (Burridge et al. 1999a) |
May accumulate in aquatic biota |
100-150 mg(Cu)·kg-1 in sediment may affect benthic fauna diversity (Debourg et al. 1993); Most sample locations > ISQGc of 18.7 mg·kg-1 , lethal to amphipods and echinoids (Burridge et al. 1999a) |
| Iodophors |
Disinfecting equipment |
Not expected (Zitko 1994) |
Formulations may contain compounds harmful or toxic to aquatic biota (Zitko 1994; Madsen et al. 1997; Ashfield et al. 1998) |
|
| Chlorine/Hypo-chlorite |
Disinfectant; Net cleaning |
Toxic to aquatic organisms (Zitko 1994) |
||
| PCBs, PAHs,p,p”-DDE |
Found in fish feed (Zitko 1994) |
PCBs not detectable at 0.05-0.10 mg·g-1 dry wt (Burridge et al. 1999a); p,p’-DDE detected at DL=1 ng·g-1, dry wt (Hellou et al. 2000) |
Changing lipid profiles in wild fish (Zitko 1994) |
|
| Cadmium, Lead, Copper, Zinc, Mercury |
From cage structures; Fish feed |
Copper >2, zinc 1-2 times higher in sediments below cages than in fish feed (Chou et al. 2002); Cadmium exceeded 0.7 mg·g-1 (Burridge et al. 1999a) |
May be toxic or accumulate in aquatic biota |
|
| Polystyrene beads |
Styrofoam floats |
Source of low molecular weight contaminants (Zitko 1994) |
Benthic fauna altered by altering pore water gas exchange, by ingestion or by providing habitat for opportunistic organisms (Goldberg 1997) |
** The table includes only compounds known to be used (presently or historically) in Canada. Other classes of compounds are used routinely in other jurisdictions and may be introduced to Canada in the future.
a – log Kow = logarithm of the octanol-water partition coefficient. It is internationally accepted that log Kow >= 3 indicates a potential to bioaccumulate. The Canadian Environmental Protection Act (CEPA) recognizes log Kow >= 5 as indicative of potential to persist and/or bioaccumulate (Beek et al. 2000).
b – NOEC = No Observed Effect Concentration
c – ISQG = Interim Sediment Quality Guidelines
The complete papers can be found in the following document: Fisheries and Oceans Canada. 2003. A scientific review of the potential environmental effects of aquaculture in aquatic ecosystems. Volume 1. Far-field environmental effects of marine finfish aquaculture (B.T. Hargrave); Ecosystem level effects of marine bivalve aquaculture (P. Cranford, M. Dowd, J. Grant, B. Hargrave and S. McGladdery); Chemical use in marine finfish aquaculture in Canada: a review of current practices and possible environmental effects (L.E. Burridge). Can. Tech. Rep. Fish. Aquat. Sci. 2450: ix + 131 p. |
REFERENCES
Anonymous. 2002. Review and synthesis of the environmental impacts of
aquaculture. A report by the Scottish Association for Marine Science and
Napier University. Submitted to the Scottish Executive Central Research
Unit 2002. 71 p.
Ashfield, L.A., T.G. Pottinger and J.P. Sumpter. 1998. Exposure of female
rainbow trout to alkylphenolic compounds results in modifications to growth
and ovasomatic index. Environ. Toxicol. Chem. 17: 679-686.
Beek, B., S. Bohling, U. Bruckmann, C. Franke, U. Johncke and G. Studinger.
2000. The assessment of bioaccumulation, p. 239-276. In B. Beek [ed.].
The handbook of environmental chemistry Vol. 2 (Part J): Bioaccumulation
new aspects and developments.
Björklund, H., J. Bondestam and G. Bylund. 1990. Residues of oxytetracycline
in wild fish and sediments from fish farms. Aquaculture 86: 359-367.
Björklund, H., C.M.I. Råbergh and G. Bylund. 1991. Residues
of oxolinic acid and oxytetracycline in fish and sediments from fish farms.
Aquaculture 97: 85-96.
Burridge, L.E. and K. Haya. 1993. The lethality of Ivermectin, a potential
agent for treatment of salmonids against sea lice, to the shrimp Crangon
septemspinosa. Aquaculture 117: 9-14.
Burridge, L.E., K. Doe, K. Haya, P.M. Jackman, G. Lindsay and V. Zitko.
1999a. Chemical analysis and toxicity tests on sediments under salmon
net pens in the Bay of Fundy. Can. Tech. Rep. Fish. Aquat. Sci. 2291:
iii + 39 p.
Burridge, L.E., K. Haya, S.L. Waddy and J. Wade. 2000a. The lethality
of anti-sea lice formulations Salmosan (azamethiphos) and Excis? (cypermethrin)
to Stage IV and adult lobsters (Homarus americanus) during repeated short-term
exposures. Aquaculture 182: 27-35.
Burridge, L.E., K. Haya and S.L. Waddy. 2000b. The effects of azamethiphos
on survival and spawning success in female American lobster (Homarus americanus)
(abstract), p. 58. In K.C. Penney, K.A. Coady, M.H. Murdoch, W.R. Parker
and A.J. Niimi [eds.]. Proceedings of the 27th Annual Aquatic Toxicity
Workshop: October 1-4, 2000, St. John’s, Newfoundland. Can. Tech.
Rep. Fish. Aquat. Sci. 2331.
Burridge, L.E., S.L. Waddy, K. Haya, M.N. Hamilton, S.M. Mercer and R.
Endris. 2002. The effects of pesticides used in aquaculture on American
lobsters (abstract), p. 65. In C.V. Eickhoff, C.V., G.C. van Aggelen and
A.J. Niimi [eds.]. Proceedings of the 29th Annual Aquatic Toxicity Workshop:
Oct 21-23, 2002, Whistler, British Columbia. Can. Tech. Rep. Fish. Aquat.
Sci. 2438.
Canadian Aquaculture Industry Alliance. 2001a. Anne McMullin comment.
Press Release from CAIA. (www.aquaculture.ca/English/PressReleases/CAIA_PressReleases10.
html) (accessed 9 January 2003).
Canadian Aquaculture Industry Alliance. 2001b. Dave Rideout comment. Press
Release from CAIA. (www.aquaculture.ca/English/PressReleases/CAIA_PressReleases
16.html) (accessed 9 January 2003).
Capone, D.G., D.P. Weston, V. Miller and C. Shoemaker. 1996. Antibacterial
residues in marine sediments and invertebrates following chemotherapy
in aquaculture. Aquaculture 145: 55-75.
Chou, C.L., K. Haya, L.A. Paon, L. Burridge, and J.D. Moffatt. 2002. Aquaculture-related
trace metals in sediments and lobsters and relevance to environmental
monitoring program ratings (EMP) for near-field effects. Mar. Pollut.
Bull. 44 (11): 1259-1269.
Committee for Veterinary Medicinal Products. 1999. Azamethiphos. Summary
report (2). EMEA/MRL/527/98-FINAL. The European Agency for the Evaluation
of Medicinal Products, Veterinary Evaluation Unit, London, U.K.
Debourg, C., A. Johnson, C. Lye, L. Tornqvist and C. Unger. 1993. Antifouling
products pleasure boats, commercial vessels, nets, fish cages, and other
underwater equipment. KEM Report No. 2/93. The Swedish National Chemicals
Inspectorate. 58 p.
Department of Fisheries and Oceans. 1997. Report to the Provincial Environmental
Assessment Review of Salmon Aquaculture in British Columbia. 114 p.
Ellis, D.W. 1996. Net loss: the salmon netcage industry in British Columbia.
The David Suzuki Foundation, Vancouver, BC. 195 p.
GESAMP (IMO/FAO/UNESCO-IOC/WMO/WHO/IAEA/UN/UNEP Joint Group of Experts
on the Scientific Aspects of Marine Environmental Protection). 1997. Towards
safe and effective use of chemicals in coastal aquaculture. Rep. Stud.
GESAMP No. 65, Rome, Italy. 40 p.
Goldberg, E.D. 1997. Plasticizing the seafloor: an overview. Environ.
Technol. 18: 195-202.
Goldburg, R. and T. Triplett. 1997. Murky waters: environmental effects
of aquaculture in the United States. Environmental Defense Fund. 16 p.
Hansen, P.K., B.T. Lunestad and O.B. Samuelsen. 1993. Effects of oxytetracycline,
oxolinic acid, and flumequine on bacteria in an artificial marine fish
farm sediment. Can. J. Microbiol. 39: 1307-1312.
Hektoen, H., J.A. Berge, V. Hormazabal and M. Yndestad. 1995. Persistence
of antibacterial agents in marine sediments. Aquaculture 133: 175-184.
Hellou, J., K. Haya, L. Burridge, S. Steller and C. Chou. 2000. Organic
contaminants including PAHs, PCBs, and DDTs in sediments collected under
aquaculture cages, p. 111. In K.C. Penney, K.A. Coady, M.H. Murdoch, W.R.
Parker and A.J. Niimi [eds.]. Proceedings of the 27th Aquatic Toxicity
Workshop: October 1-4, 2000, St. John’s, Newfoundland. Can. Tech.
Rep. Fish. Aquat. Sci. 2331.
Hirvelä-Koski, V., P. Koski and H. Niiranen. 1994. Biochemical properties
and drug resistance of Aremonas salmonicida in Finland. Dis. Aquat. Org.
20: 191-196.
Johnson, S.C., M.L. Kent, D.J. Whitaker and L. Margolis. 1993. Toxicity
and pathological effects of orally administered ivermectin in Atlantic,
chinook, and coho salmon and steelhead trout. Dis. Aquat. Org. 17: 107-112.
Jones, O.J. 1990. Uptake and depuration of the antibiotics, oxytetracycline
and Romet-30 in the Pacific oyster, Crassostrea gigas (Thunberg). M.Sc.
Thesis, University of British Columbia, Vancouver, BC. 221 p.
LeBris, H., H. Pouliquen, J-M. Debernardi, V. Buchet and L. Pinault. 1995.
Preliminary study on the kinetics of oxytetracycline in shellfish exposed
to an effluent of a land-based fish farm: experimental approach. Mar.
Environ. Res. 40: 587-595.
Madsen, S.S., A.B. Mathiesen and B. Korsgaard. 1997. Effects of 17?-estradioal
and 4-nonylphenol on smoltification and vitellogenesis in Atlantic salmon
(Salmo salar). Fish Physiol. Biochem. 17: 303-312.
McHenery, J.G. 1997. Predicted environmental concentrations and risk assessment
for use of calicide in an environmental effects study at two salmon farms
under commercial use conditions. Report to Nutreco ARC. Referenced in
SEPA (1999b).
Milewski, I., J. Harvey and B. Buerkle. 1997. After the gold rush: the
status and future of salmon aquaculture in New Brunswick. Conservation
Council of New Brunswick, Fredricton, NB. 61 p.
Nash, C.E. [ed.]. 2001. The net-pen salmon farming industry in the Pacific
northwest. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-49. 125 p.
Roth, M., R.H. Richards and C. Sommerville. 1993. Current practices in
the chemotherapeutic control of sea lice infestations in aquaculture:
a review. J. Fish Dis. 16: 1-26.
Roth, M., R.H. Richards, D.P. Dobson and G.H. Rae. 1996. Field trials
on the efficacy of the organophosphate compound azamethiphos for the control
of sea lice (Copepoda: Caligidae) infestations of farmed Atlantic salmon
(Salmo salar). Aquaculture 140: 217-239.
Roy, W.J., I.H. Sutherland, H.D.M. Rodger and K.J. Varma. 2000. Tolerance
of Atlantic salmon, Salmo salar L. and rainbow trout, Oncorhynchus mykiss
(Walbaum), to emamectin benzoate, a new orally administered treatment
for sea lice. Aquaculture 184: 19-29.
Samuelsen, O.B. 1994. Environmental impacts of antimicrobial agents in
Norwegian Aquaculture, p 107-113. In A. Ervik, P. Kupa Hansen and V. Wennevik
[eds.]. Proceedings of the Canada-Norway Workshop on the Environmental
Impacts of Aquaculture. Fisken Havet 13.
SEPA. 1999b. Calicide (teflubenzuron) – authorization for use as
an in-feed sea lice treatment in marine cage salmon farms. Risk assessment,
EQS and recommendations. Policy 29. Scottish Environmental Protection
Agency, Fish Farming Advisory Group. 13 p.
Sievers, G., P. Palacios, R. Inostroza and H. Dolz. 1995. Evaluation of
the toxicity of eight insecticides in Salmo salar and the in vitro effects
against the isopod parasite, Ceratothoa gaudichaudii. Aquaculture 134:
9-16.
Stewart, J.E. 1994. Aquaculture in Canada and the research requirements
related to environmental interactions with finfish culture, p. 1-18. In
A. Ervik, P. Kupa Hansen and V. Wennevik [eds.]. Proceedings of the Canada-Norway
Workshop on the Environmental Impacts of Aquaculture. Fisken Havet 13.
Tomlin, C.D.S. [ed.]. 1997. The pesticide manual – A world compendium.
British Crop Protection Council, Surrey, U.K. 1606 p.
Waddy, S.L., L.E. Burridge, M.N. Hamilton, S.M. Mercer, D.E. Aiken and
K. Haya. 2002c. Emamectin benzoate induces molting in American lobster,
Homarus americanus. Can. J. Fish. Aquat. Sci. 59: 1096-1099.
Wislocki, P.G., L.S. Grosso and R.A. Dybas. 1989. Environmental aspects
of abamectin use in crop protection, p. 182-200. In W. Campbell [ed.].
Ivermectin and Abamectin. Springer-Verlag, New York, NY.
Zitko, V. 1994. Chemicals in aquaculture (an overview), p. 97-106. In
A. Ervik, P. Kupa Hansen and V. Wennevik [eds.]. Proceedings of the Canada-Norway
Workshop on the Environmental Impacts of Aquaculture. Fisken Havet 13.
Zitko, V. 2001. Alkylating potency of azamethiphos. Bull. Environ. Contam.
Toxicol. 66: 283-286.
