There is a lot of research about the positive benefits of aquaculture.  Much of that research is done by the aquaculture industry and their contracted scientists.  Their argument is that they feed the world.  That is true.  Ten years ago, there was not much information about the negative side of aquaculture.  Fortunately,  more current and unbiased research of this is emerging from reputable sources, universities and governments around the world. 

 Following are just a few of the links to whole articles (or locations of articles) with a brief description of the article or some interesting aspect of the article.  The articles have been broken down by category, however, some articles may cover more than one topic.  Remarks in italics represent the views of APHETI.

                                                                   Definitions:

Carrying Capacity:  For any given environment, the carrying capacity is the amount of activity that can be supported in a sustainable manner. If pressures of population, extraction of materials, or pollution exceed his limit, the environment will suffer long term damage. : www.ideaknowledge.gov.uk/idk/core/page.do

Eutrophication:   over-enrichment of a water body with nutrients, resulting in excessive growth of organisms and depletion of oxygen concentration
www.royalbcmuseum.bc.ca/end_species/es_gloss/es_gloss.html -

Phytoplankton: Microscopic floating plants, mainly algae, that live suspended in bodies of water and that drift about because they cannot move by themselves or because they are too small or too weak to swim effectively against a current.
www.streamnet.org/pub-ed/ff/Glossary/glossaryfish.html 

Seston:  suspended particulate matter in water.
gmbis.marinebiodiversity.ca/BayOfFundy/glossQ-T.html 

GENERAL NEGATIVE IMPACTS

http://govdocs.aquake.org/cgi/reprint/2004/410/4100100.pdf.

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http://www.davidsuzuki.org/files/Oceans/Shellfish.pdf

“Sustainable Shellfish: Recommendations for Responsible Aquaculture” by Heather Deal, M. Sc., David Suzuki Foundation.    Explains clearly all the concerns regarding intensive aquaculture: cumulative effects,biodiversity, carrying capacity, non-native species, siting and disruptions or destruction of fish habitat.  Also offers suggestions.

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http://www.springerlink.com/content/ptybc0qg8y4klr5c/

"Harmful algal blooms: causes, impacts and detection" by Kevin G Sellner, Gregory J Doucette and Gary J Kirkpatrick, Rec'd 5 Feb 2003, Accepted 5 May 2003, Pub online 30 Jul 2003

Abstract  Blooms of autotrophic algae and some heterotrophic protists are increasingly frequent in coastal waters around the world and are collectively grouped as harmful algal blooms (HABs). Blooms of these organisms are attributed to two primary factors: natural processes such as circulation, upwelling relaxation, and river flow; and, anthropogenic loadings leading to eutrophication. Unfortunately, the latter is commonly assumed to be the primary cause of all blooms, which is not the case in many instances. (This is precisely the case of Totten Inlet, WA where there has been NO fecal coliform contamination, and no industrial or agricultural run-off yet the water icreasingly turbid and on the verge of becoming eutrophic -- too much aquaculture?)  Moreover, although it is generally acknowledged that occurrences of these phenomena are increasing throughout the world's oceans, the reasons for this apparent increase remain debated and include not only eutrophication but increased observation efforts in coastal zones of the world. There is a rapidly advancing monitoring effort resulting from the perception of increased impacts from these HABs, manifested as expanding routine coastal monitoring programs, rapid development and deployment of new detection methods for individual species, toxins, and toxicities, and expansion of coastal modeling activities towards observational forecasts of bloom landfall and eventually bloom prediction. Together, these many efforts will provide resource managers with the tools needed to develop effective strategies for the management and mitigation of HABs and their frequently devastating impacts on the coastal environment.

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http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADP006836

Title :   Relationship Between Sediment Pollution and Macrobenthic Communities in Hiroshima Bay, Japan, Yoshida, K. for Japan Sediments Management Association Tokyo, Apr 1992

Abstract : Distribution of sediment, macrobenthos, and the anoxic water mass in Hiroshima Bay was investigated. The accumulation of organic matter in the sediment was considerable in the semi-closed bays, such as Kure and Edajima, and in the mouth of the Ota River. In Kure Bay, particularly, the benthic communities were of very poor condition or had disappeared, apparently due to the anoxic water mass. It is thought that the occurrence of the anoxic water mass in Kure Bay was mainly caused by the oxygen demand due to decomposition of the organic matter in the sediment, which can be determined from the distribution of the temperature, salinity, and dissolved oxygen and from the subtidal current.

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http://www.bim.ie/uploads/text_content/docs/ECOPACT.pdf

“Environmental Code of Practice for Irish Aquaculture Companies and Traders”, Federation of European Aquaculture Producers Stocking Density: “The stocking density for fish should be adjusted to the specific requirements of the species and include respect for 1) the average live weight of the fish; 2) the population’s health and behavioral needs; 3) the population’s demands on the growing environment.  In particular their behavioral needs, the availability of an adequate oxygen supply and the removal of wastes to avoid the excessive accumulation of substances that may cause stress or toxic effects (e.g. C)2 and ammonia)” per page 78, and odor control on p. 27.  Carrying capacity, waste

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http://www.dfo-mpo.gc.ca/csas/Csas/status/2006/SAR-AS2006_005_E.pdf  explains parameters of assessment for near field and far field impacts of intensive mussel farming  “Assessing Habitat Risks Associated With Bivalve Aquaculture within the Marine Environment”, 10 pages.  Canadian Science Advisory Secretariat 2005   

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http://66.102.7.104/search?q=cache:fA0vLaw8wn0J:lingzis.51.net/papers/  “Development of Mariculture and its Impacts in Chinese Coastal Waters” by Feng et al, Springer 2005  Reviews in Fish Biology and Fisheries 2004 14:1-10.  A report re various forms of intensive aquaculture, including mussels and other shellfish, and impacts, and the needs for better controls

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http://govdocs.aquake.org/cgi/reprint/2004/628/6280160.pdf   

“Impacts of Marine Farming on Wild Fish Populations” by Russell Cole – includes mussel farming impacts.

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http://darwin.nap.edu/books/0309046750/html/92.html

“Marine Aquaculture: Opportunities for Growth 1992”       Commission on Engineering and Technical Systems, Environmental Impacts, Shellfish Intensive Farming p. 93-94

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http://www.psat.wa.gov/Programs/shellfish/fact_sheets/ecology_web1.pdf  Article put out by the PSAT (Puget Sound Action Team) with photos from Taylor.  (Again they claim that bivalves clean the water by having the shellfish suck up all inorganic matter to prevent eutrophication, however, they neglect to mention that eutrophication occurs under mussel rafts due to the detritus from the mussels.  There is a Taylor photo no eel grass in Totten, and after 116 years of aquaculture by the Taylor Industry, Totten should be teeming with eelgrass if their claims were true)

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WATER CIRCULATION TO REMOVE WASTE AND BRING IN PHYTOPLANKTON

http://www.ices.dk/reports/MCC/2003/WGMASC03.pdf

“Roles of tidal flushing, internal production, bivalve grazing on seston levels”  International Council for the Exploration of the Seas, 13-15 August 2003  Quote “These order of magnitude calculations strongly suggest that intensive bivalve culture has the capacity to alter particulate food supplies for long periods in some coastal systems as a result of limitations in the tidal exchange of food from outside the system . . ." section 7.3, ,pp 7-9. 

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http://www.nwfsc.noaa.gov/publications/techmemos/tm45/background.htm -  “Status Review of Pacific Herring (Clupea pallasi) in Puget Sound, Washington” by Heather A Stout, et al, Northwest Fisheries Science Center.  Distribution of sea grasses, esp. eel grass,”largely devoid in South Puget Sound”, also speaks to poor mixing (getting nutrients in and pollutants out) in South Sound compared to rest of Puget Sound. 

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http://www.piercecountywa.org/xml/abtus/ourorg/exec/specialprojects/chinookrecovery/Nearshore/

SPSSR%20Plan%20Draft%20V1.pdf           

Excellent paper by So. Puget Sound Salmon Recovery Group written in 2004.  Starts off by stating poor circulation, lack of mixing and diluting nutrients and slow flushing of south Sound; mud and sand flats of the intertidal region of So. Puget Sound are typically devoid of emergent vegetation but can support benthic invertebrates and eel grass that are essential food for higher organisms, like fin fish. ( The desired habitat for bull trout and Chinook and what is occurring with aquaculture does not mesh.  Pages 27 – 30 talk about how decreased light impedes growth of eel grass.  Interesting are the “human induced stressors” which the aquaculture industry is listed as one, but there are other things that industry does that are also stressors, such as overwater structures (nets, bags, rafts, tubes) on p. 35, high high water line landfill ( such as the detritus below the mussel rafts) on p. 38, wetland and estuary modification on p. 40, invasive species like the introduced Mytilus galloprovincialis and it’s attraction for club and colonial tunicates on p. 45.  There are graphs indicating that Aquaculture is heavily influencing Totten, and they also mention riparian loss (which is minimal) and armoring (also minimal compared to other inlets) on p. 53.  The only identified intact eel grass beds are located in Case Inlet on p. 57.  On p. 64, it is mentioned that the Pacific Coast Shellfish Growers Industry has developed Environmental Codes of Practice, but they don’t mention that the players in that organization are aquaculture promoters (fox in charge of the henhouse), and on p. 67 it talks that shellfish regulations are needed, and that not too much is known about shellfish impacts to finfish.  This is a critical piece of information, even in its draft form!!)

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http://www.scotland.gov.uk/library2/doc06/mff-27.htm

ADVICE NOTE : MARINE FISH FARMING AND THE ENVIRONMENT

Sustainable marine fish farming requires that the levels of nutrient and chemical inputs are not allowed to exceed the carrying capacity of the surrounding aquatic environment. There is clearly a need to ensure that, within any enclosed body of water, the total nutrient input from fish farming and other sources does not exceed the threshold above which an unacceptable increase in phytoplankton production or undesirable changes in species composition would occur. . .   . . .

 . . .Although shellfish cultivation does not rely on food input, the material discarded by filter-feeding molluscs can result in accumulations of organically-rich detritus on bottom sediments beneath shellfish farms.

In inshore marine locations it is important to select sites with good water exchange characteristics. Strong the case of shellfish cultivation, provide fresh supplies of planktonic food. Sites in deeper water permit higher levels of production per unit surface area, are less susceptible to souring as a result of the accumulation of waste material, and generally have more stable salinities. Seabed survey can assist in marine site selection. Sites with thick, muddy sediments tend to have less vigorous water exchange characteristics. Sand and gravel sediments indicate that the site is well flushed.

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http://www.piercecountywa.org/xml/abtus/ourorg/exec/specialprojects/chinookrecovery/

Nearshore/SPSSR%20Plan%20Draft%20V1.pdf#search=%22South%20Puget%20

Sound%20Recovery%20Group%20Chinook

%20and%20Bull%20Trout%20Recovery%20report%22

Draft%20V1.pdf

“South Puget Sound Salmon Recovery Group:  Chinook & Bull Trout Recovery Approach for the South Puget Sound Nearshore, Draft Version July 2004”, for review purposes only – page 4:  Numerous shallow, blind-end inlets divide South Puget Sound that causes poor circulation.  As a result, water does not mix or dilute nutrient inputs to the same degree as the deeper, more tidally mixed areas such as the central Puget Sound basin, which has depths that often exceed 200 meters.  The shallow nature of South Puget Sound, along with the slow flushing time, provides a greater amount of sandy habitat and makes many of the bays and inlets more productive than the rest of Puget Sound.  Two consequences of such conditions are:  1)  Different florae and faunae associated with the different sediment and benthos of South Puget Sound, and 2) An increased risk of pollutant concentration from land derived sediments in the South Puget Sound catchment area.  Llanso (1998) investigated these types of effects and found that the inlet ends of South Puget Sound had lower species diversity compared to the rest of Puget Sound.  Furthermore, the species present appear to be associated with a combination of fine sediments and low DO (dissolved oxygen).   ( Does intensive aquaculture contribute to this?)

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CARRYING CAPACITY

http://www.govdocs.aquake.org/cgi/reprint/2004/628/6280090.pdf

“An Overview of Factors Affecting the Carrying Capacity of Coastal Embayments for Mussel Culture” by Graeme J. Inglis, et al.  Ministry for the Environment (NZ)   carrying capacity of mussel farm areas of Beatrix Bay NZ.  Great article with parameters for determining phytoplankton abundance, and the effects of intensive farming locally and of the benthic community.  Sections 3.2.1, 3.3, 3.3.2, 3.3.3.2, p. 13-14, and 3.3.3.3 reports that the Mytilus galloprovincialis is a fouling organism, comprising the growing of their own stocks of green mussels

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http://www.aquachallenge.org/workshop_materials/Qisheng.pdf

“Impacts of Intensive Mariculture on Coastal Ecosystems and Environment in China and Suggested Sustainable Management Measures” by Qishing Tang and Jianguang Fang for the Yellow Seas Fisheries Institute, published 2000.  Even the Chinese are weighing in on carrying capacity and too much aquaculture.

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http://www.springerlink.com/content/xj526u6m2681r450/      

“A Review of the Feedbacks between Bivalve Grazing and Ecosystem Processes” Abstract:  “This paper gives an overview of interactions between bivalve grazing and ecosystem processes, that may affect the carrying capacity of ecosystems for bivalve suspension feeders. These interactions consist of a number of positive and negative feedbacks. Bivalve grazing can result in local food depletion, which may negatively influence bivalve growth. On a larger scale, it may induce a top-down control of phytoplankton biomasss, and structural shifts in phytoplankton composition. In the case of harmful algal blooms, phytoplankton may negatively affect bivalve grazing rates. The processing of large amounts of particulate matter may change nutrient cycling on the scale of estuaries, and can result in changes in the inorganic nutrient pool available for phytoplankton, through regeneration and reduced storage of nutrients in algal biomass. This can reduce nutrient limitation of the phytoplankton and stimulate algal growth rates.  Observations from mesocosm studies suggest that a positive feedback from bivalve grazing on phytoplankton growth may also change the physiological state of the algae and improve food quality.” Authors: AC Smaal, RF Dame, TC Prins Netherlands Institute of Ecology, Centre for Estuarine and Coastal Ecology, PO Box 140, 4400 AC Yerseke, The Netherlands,

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http://www.fra.affrc.go.jp/english/bull/s1eng.html#The2

“The Present Situation and Problems of Oyster Culture in Hiroshima Bay” by  Yasushi HIRATA and Satoru AKASHIGE - Hiroshima Bay including its adjacent area is one of the most important oysters farming areas in Japan. During 1980s, the oyster production in Hiroshima Bay was about 30,000 metric tons (t) scale by fresh meat weight (FMW) a year. In the early 1990s, the oyster production began to decrease and was about 20,000t in 2000. We analyzed the present situation and problems of oyster culture in Hiroshima Bay to show the problem solution. This decrease in oyster production in the 1990s was caused directly by typhoon damages; shellfish poisoning by Alexandrium spp.; and mortality by harmful dinoflagellate Heterocapsa circularisquama: and was caused by dense cultivation indirectly. The postponing of harvesting the oyster caused by shellfish poisoning prolonged the oyster culture period. The prolongation of the culture period in a limited culture ground caused eventually dense cultivation of oyster. Aged and large-sized oysters took much feed, therefore growth of all oysters in culture grounds were slowed down under low feed level. The low growth rate accelerated prolongation of a culture period. These vicious spirals promoted dense cultivation, and changed the environment of the culture ground into favorable environment for H. circularisquama. To analyze these situations, an oyster culture process model was built. This model showed that the reduction in oyster biomass in the culture grounds is needed to escape from the vicious spiral, and shortening of the culture period was the most effective method for this reduction without reducing harvest magnitude.

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http://www.fra.affrc.go.jp/english/bull/s1eng.html#The3

“Influence of Environmental Changes in the Tidal Flats on the Filtration and Respiration of Bivalve Mollusks” by Junya Higano.  Manila clam Ruditapes philippinarum and the other filter feeding bivalves in tidal flat are not only commercially important as seafood, but also ecologically significant because of their filtration activity. The volume of water filtration by bivalves in Ariake Sound is estimated to be equivalent to daily water exchange on the tidal flat in 1970s. However, the annual catch of Japanese littleneck has been decreased during the past 20 years in Japan. Especially, rapid decrease in the clam population in Ariake Sound since 1980s forced to depress the nationwide production. Recent coastal changes such as land reclamation, dike, port, barrage, and dam construction presumably brought about the environmental impact for filter feeding bivalves through water and sediment movement. Higher intertidal zone and supralittoral zone are intercepted by artificial structure such as dike and breakwater. Consequently suspended sediments are prevented from depositing at the higher intertidal zone and are drifted in littoral zone. High concentration of mud particles suppresses the water clearance of the clams. On the other hand, reduction of water current by barrages encourages the stratification.  Hypoxia and anoxia often occur in subtidal zone of eutrophied sheltered coast under the stratified layer in summer. Complex effects of mud increase and oxygen shortage are considered to be physiologically harmful to filter feeding bivalves. The ecological function of tidal flat has been destroying and it disturbs the recovery of the bivalve resources.

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http://www.fra.affrc.go.jp/english/bull/s1eng.html#The3  "Environmental Carrying Capacity in an Aquaculture Ground of Seaweeds and Shellfish in Sanriku Coast” by Ken Furuya.  In non-feeding aquaculture of seaweeds and shellfish the culture organisms compete with natural populations for resources, viz. nutrient salts and food particles. Therefore evaluation of carrying capacity of coastal waters is crucial for sustainable exploitation of biological productivity. For this two major criteria are proposed: accurate estimation of phytoplankton primary production which governs the magnitude of total biological productivity, and understanding of oxygen dynamics based on a preliminary study in a bay on the northeastern coast of Japan.

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http://www.ifremer.fr/docelec/doc/2002/publication-481.pdf

“Shellfish Farming and Coastal Zone Management (CZM) Development in the Marennes-Oleron Bay and Charentais Sounds (Charente Maritime, France): a review of recent developments” by P. Goulletquer and O. Le Moine, 2002   Carrying capacity exceeded  by overgrowth of oysters leading to decreased economic yield, progressive increase of culture stocking mass which led to increased oyster mortality rate and decrease in growth performance.  Oyster larvae require decreased salinity to survive so less fresh water flow (from upland irrigation) led to increased larval mortality.  Land farmers vs. sea farmers compete with each other, so France considering moving all oyster production off shore, away from potential point sources of pollution.  Shellfish farmers also compete with commercial finfishers, public fishermen/women, tourism, and shipping companies when their long lines interfere with navigation and of course, environmentalists.

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ESCAPEMENT, HYBRIDIZATION, SPECIES DISPLACEMENT

http://fishweb.ifas.ufl.edu/Faculty%20Pubs/SBaker%20Pubs/SBAKER2003.PDF

“Selective Feeding by Three Native North American Freshwater Mussels Implies Food Comptetion with Zebra Mussels” by Shirely Baker, et al.  article re different freshwater mussels capable of sorting particles and all sharing preferences for similar types of phytoplankton, and the zebra mussel outcompeting the native mussels - pseudofeces examined - Florida 

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http://fishweb.ifas.ufl.edu/Faculty%20Pubs/SBaker%20Pubs/SBakerMusselFeed.pdf,

“Selective Feeding and Biodeposition by Zebra Mussels and their Relation to Changes in Phytoplankton Composition and Seston Load” by Shirley Baker, et al.  more of the same type as previous article but of Hudson Bay, replication

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http://www.nywea.org/clearwaters/pre02fall/314080.html 

 “Diminishing species richness of mollusks in Oneida Lake" ,NY, USA, the Nautilus 114 (3): 120-126   Oneida Lake:  Undergoing Ecological Change - Zebra mussel efficiently CLEARING the water of Lake Oneida, NY with peak clearing in 1994, 1995, and 1997, caused native bivalve clam population to decline (Harman 2000) reports “that six species of bivalves have gone extinct from direct competition from zebra mussels.”  Clearing the turbidity has allowed some unwanted organisms to grow disproportionately and allowed other natives to go extinct.  (Harman, W.N. 2000)

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http://www.blackwell-synergy.com/links/doi/10.1046/j.1523-1739.1999.97470.x/abs/

“Decline of a Native Mussel Masked by Sibling Species Invasion” bv J. B. Geller 1999, Mytilus galloprovincialis displacing native M. trossolus.

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http://english.dirnat.no/archive/attachments/01/26/Actua059.pdf

“Research Report 2001-1, Actual and Potential Effects of Introduced Marine Organisms in Norwegian Waters Including Svalbard”, Directorate for Nature Management.  Good report on negative impacts when non-native species are introduced or farmed in areas; causes are aquaculture and ballast water.  Note pp. 9-11, and 31.

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NON-NATIVE INVASIVE SPECIES – IMPACTS

http://www.davidsuzuki.org/files/Oceans/Shellfish.pdf  -     "Sustainable Shellfish" by David Suzuki Foundation – p. 12 Gallos on the most invasive species list there – (good article, 41 pp. about negative impacts and poor study of many impacts and need for better science, etc.)

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http://praise.manoa.hawaii.edu/news/Priorityspecies_draft2.doc

Draft document May 6, 2003, “State of Hawaii Aquatic Nuisance Species Plan Priority Species – Freshwater and Marine” by Mike Yamamoto, Dept. of Land and Natural Resources.  Introductions by aquaculture and ballast water.  Note p. 7: “Mytilus galloprovincialis (Smooth-shelled Blue Mussel)

Of the three species of smooth mussel M. galloprovincialis is the most widely distributed and typically occurs in warm temperate regions. It is native to the southwest coast of Europe and the Mediterranean Sea and has been introduced into Japan, Hong Kong, South Africa and the West Coast of North America. Evidence from locations in which it has invaded shows that it is a competitively dominant species and has established alongside native competitors or has displaced local established species. Maritime commerce activities and aquaculture have transported this species outside its native range.”

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http://www.engr.washington.edu/epp/psgb/2005psgb/2005proceedings/Papers/P2_RENSE.pdf

"Will the introduced mussel Mytilus galloprovincialis outcompete the native mussel M. trossulus in Puget Sound?"  A study of relative survival and growth rates among different habitats by Michelle Rensel, Joel Elliott, and Peter Wimberger, Dept of Biology, University of Puget Sound, 2006

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http://www2.ups.edu/biology/thesistitles.html

“Distribution, Hybridization and Morphology of Mytilus trossulus, Mytilus galloprovincialis and their hybrids in marine communities adjacent to aquaculture operations in Puget Sound”, by Kathleen J. Holmes, Dec. 5, 2003 University of Puget Sound Biology Department– morphology compared to dna – cheaper method of identification, includes process and ratio; evidence of introduction of the non-native species Mytilus galloprovincialis mussel into Puget Sound.

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http://www2.ups.edu/biology/thesistitles.html

"Factors influencing the distribution and abundance of the Mediteranean mussel Mytillus galloprovincialis, the Native Mytilus trossulus, and their hybrids in Puget Sound" by Rachel A. Chambers, May 16, 2003 University of Puget Sound Biology Department – evidence of introduction of he non-native species M. galloprovincialis into Puget Sound Waters

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http://darwin.nap.edu/books/0309046750/html/92.html

“Marine Aquaculture: Opportunities for Growth 1992”       Commission on Engineering and Technical Systems, Environmental Impacts, Shellfish Intensive Farming p. 93-94

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CONTAMINANTS – BIVALVES CLEAR WATER OR CLEAN IT?

http://www.westcoastaquatic.ca/WCVI%20Water%20Quality%20Report%20Sept%202005.pdf    “Marine Water Quality on the West Coast of Vancouver Island”, good overview of shellfish concerns re contaminants, fecal coliforms (NOT human caused), testing, bacterial and viral testing/excretion – pp. 13-14, 19 – 22 (cadmium levels), 24 (international market standards), 44 (shellflish concentrating pathogens, biotoxins and chemicals from 3 to 20 times the level of surrounding waters)

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http://www.cvm.ncsu.edu/wb/bivalves.html

Very interesting experiment via North Carolina State Univ. 1998-2000 – looks like no new data since 2000.  Wilson Bay Water Quality Initiative.  It states “Bivalves (i.e.. Oysters, clams, etc) are one of nature’s filtering systems.  Bivalves filter large volumes of water CLEARING suspended phytoplankton, bacteria and organic debris.  Bivalves are being planted in Wilson Bay to increase natural biologic filtration.  Progeny that are recruited from the reproduction of planted bivalves will help sustain achieved water quality improvement”.  (Note:  this is not a cure but one method they mention in addition to improving the riparian habitat above).  Under Water Quality Objectives #2, Planting Bivalves to improve water quality, it states “Bivalves help improve water CLARITY by reducing turbidity and reducing the total organic load.  The feces and pseudofeces (from material they cannot digest) is more readily available to other organisms for degradation.”  (Does not talk about anoxic conditions that occur with bacterial digestion of excess phytoplankton, smothering due to excess shellfish nutrient, in other words, what happens below the shellfish. So again, they clear, not clean – there is a distinction.  There is also no mention of inorganic substances like metals, dioxins, etc. or if these bivalves go to market for human consumption.  It looks like it only existed from 1998-2000)

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http://www.glerl.noaa.gov/pubs/brochures/wcontflyer/wcont.html

"Waterborne Contaminants in the Great Lakes," short article that states bivalves ingest some of the sediment particles and contaminants associated with them

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http://www.pices.int/publications/scientific_reports/Report16/Report16.pdf

“Environmental Assessment of Vancouver Harbor: Data Report for the PICES Practical Workshop” 2001. Interesting science on a number of issues coming out of Canada -- see p. 35 of article for discussion of PCB's and other contaminants

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http://www.pac.dfo-mpo.gc.ca/sci/osap/projects/contaminants/marine_e.htm 

B.C. studies that should be completed by now, but last few paragraphs (very short abstract) re cadmium and PCB's, dioxin studies in bivalves, oysters, mussels and phytoplankton (and we eat this shellfish??) 

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http://www.int-res.com/articles/meps/221/m221p303.pdf

“Bivalve Clearance Rates: Inaccurate Measurements or Inaccurate Reviews and Misrepresentations” by John Widdows.  very interesting and short article that alludes to that even bivalves have limits to polluted water intake

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OTHER INTERESTING SCIENCE

http://www.protectourshoreline.org/ThesisGeoduckHarvestImpacts.pdf   18

"The Potential Impacts of the Commercial Geoduck 

(Panope generosa) Hydraulic Harvest Method on Organisms in the 

Sediment and at the Water-Sediment Interface in Puget 

Sound.Plan" </a></b> Georgina Wilner, Masters Thesis of Distinction, TESC, June 2006

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http://web2000.wes.army.mil/conf/ltms/dredging.pdf

"Dredging Activities:  Marine Issues, white paper" submitted to DFWL, WA Dept of Ecology an WDOT July 2001 prepared by Barbara Nightingale and Charles Simenstad, University of Washington Wetland Ecosystem Team, School of Aquatic and Fisheries Sciences some interesting facts about what the act of dredging has on small finfish and benthos, and that more science is needed. (Note the conclusions.  This article included because high pressure hose harvesting used in geoduck harvesting very  much resembles dredging.)