Growth and biochemical composition of Mytilus edulis when reared on effluent from a cod, Gadus morhua, aquaculture facility.
Mytilus edulis (Physiological aspects)
Mytilus edulis (Growth)
Codfish (Physiological aspects)
Parrish, Christopher C.
Penney, Randy W.
|Publication:||Name: Journal of Shellfish Research Publisher: National Shellfisheries Association, Inc. Audience: Academic Format: Magazine/Journal Subject: Biological sciences; Zoology and wildlife conservation Copyright: COPYRIGHT 2012 National Shellfisheries Association, Inc. ISSN: 0730-8000|
|Issue:||Date: April, 2012 Source Volume: 31 Source Issue: 1|
|Topic:||Event Code: 310 Science & research Computer Subject: Company growth|
|Product:||Product Code: 0910100 Fish Farming; 0912035 Cod NAICS Code: 11251 Animal Aquaculture; 114111 Finfish Fishing SIC Code: 0273 Animal aquaculture; 0912 Finfish|
|Geographic:||Geographic Scope: Canada Geographic Code: 1CANA Canada|
ABSTRACT This study determined the growth and biochemical
composition of blue mussels (Mytilus edulis) reared on effluent from
Atlantic cod (Gadus morhua) and compared it with mussels reared on a
standard shellfish diet. Feeding trials lasted 6 mo, and mussels were
sampled on a monthly basis. Dry weight, ash-free dry weight, shell
length, and condition index were all significantly higher in algae-fed
mussels at the end of the experiment compared with effluent-fed mussels.
The carbon content decreased for mussels fed both diets; however, their
nitrogen and protein content increased, with effluent-fed mussels having
significantly more nitrogen and protein than algae-fed mussels,
suggesting that effluent can increase mussel growth. Total lipid and
fatty acid (FA) content decreased for effluent-fed mussels at the end of
the experiment. There were no significant differences in the lipid class
composition between mussels fed the 2 diets. Mussels fed both diets
significantly decreased in the amount of 14:0, 16:1 1[omega]7,
16:2[omega]4, 16:4[omega]l and 20:5[omega]3, and effluent-fed mussels
also decreased in 18:4[omega]3 and 21:5[omega]3, as well as increased in
the amount of 17:1, the zooplankton markers 20:1[omega]11 and
22:1[omega]11, and the dienoic nonmethylene-interrupted fatty acids
(NMIDs) 20:2a and 22:2b. Significant differences in the amount of
individual FAs between mussels fed the 2 diets included a larger amount
of 18:2[omega]6 and 20:4[omega]6 in algae-fed mussels, and a
significantly larger amount of 16:4[omega]1 in mussels fed effluent.
Mussels fed both diets underwent significant increases in the proportion
of bacterial FAs, [omega]6 FAs, zooplankton markers, and NMIDs.
Effluent-fed mussels had a significantly larger proportion of
monounsaturated FAs, zooplankton markers, and NMIDs, as well as a
smaller proportion of polyunsaturated FAs, and [omega]3 and [omega]6 FAs
than algae-fed mussels. The increased presence of zooplankton markers
supports the use of these FAs to track aquaculture wastes.
KEY WORDS: mussel, IMTA, lipid, fatty acid, Mytilus edulis, cod, Gadus morhua, aquaculture
Seafood consumption has been increasing, with a recorded global consumption of 110.4 t equating to a per-capita consumption of 16.7 kg/y in 2006 (FAO 2006). Seafood is a major source of omega 3 ([omega]3) PUFAs. Bivalves are an important source of inexpensive protein (Astorga Espana et al. 2007), among which mussels are also good sources of phytosterols (Murphy et al. 2002). Phytosterols have numerous health benefits, including the ability to lower cholesterol and prevent some forms of tumors (Ling & Jones 1995).
Integrated multitrophic aquaculture (IMTA) is a practice during which fed organisms (e.g., fish) are grown alongside extractive organisms (e.g., mussels) in an attempt to reduce wastes (Barrington et al. 2009). Blue mussels grown adjacent to Atlantic salmon cages in the Bay of Fundy have been reported to have increased growth rates and are currently being sold commercially (Reid et al. 2008a, Reid et al. 2008b). It is known that the fatty acid (FA) profile of the diet fed to mussels can affect directly the FA profile of the mussel itself (Khan et al. 2006). Any changes in the biochemical composition of mussels can affect their nutritional value for their human consumers. With regard to IMTA, it is therefore important to understand how the biochemical composition of mussels will be changed through feeding them fish waste as opposed to their normal diet.
The aim of this study was to determine the performance of Mytilus edulis when reared on wastes generated from an onshore Atlantic cod (Gadus morhua) aquaculture site. This was done by assessing the physical characteristics of mussels (shell length (SL), dry weight (DW), ash-free dry weight (AFDW), and condition index (CI)) as well as the biochemical characteristics (C and N, lipid profile, FA profile, and amino acid profile) of mussels fed fish waste and by comparing them with that of mussels fed an algae diet.
Six tanks were arranged into 2 rows of 3, with 1 row being elevated above the other. The elevated tanks were set up to drain into the lower tanks. Two of the top 3 tanks contained juvenile Atlantic cod (age, 1 y; body weight, 30 g), whereas the other tank remained empty as a control. The lower row of tanks each contained 250 mussels (SL, 1.8-2.2 cm).
Fish were fed a commercial fish feed twice daily for a total of 1.5% of their body weight. Based on effluent concentrations found in previous experiments, the body mass of fish in each of the tanks was expected to provide the mussels below with at least 1.5% of their DW daily, with waste particles less than 70 gm. The standpipe for the fish tanks was pulled daily, after which the water supply was turned off for 2 h to allow the mussels more time to filter the larger concentration of waste.
Mussels below the control tank were fed 1.5% of their DW daily with a commercial shellfish diet. Water to the tank was turned off after addition of the diet for 2 h or until water clarity returned. Water samples were taken over time during this period and analyzed via a Coulter counter to determine how much algae food was removed over time.
Twenty mussels were removed from each tank on a monthly basis and sampled for SL, wet weight (WW), DW, AFDW, lipid composition, FA composition, and C/N and amino acid composition. Replacements were added to maintain a constant biomass, so the amount fed did not increase inadvertently.
Procedures used to extract and determine lipid content were based on Parrish (1999). Samples were placed in a mixture of ice-cold chloroform (methanol (2:1)) and were homogenized using a Polytron PCU-2-110 homogenizer (Brinkmann Instruments, Rexdale Ontario, Canada). Chloroform-extracted water was added creating a chloroform-to-methanol-to-water ratio of 8:4:3, after which the sample was sonicated in an ice bath for 4 to 10 min. The sample was then centrifuged at 5,000 rpm for 2 min, and the bottom organic layer was removed with a double-pipetting technique. Chloroform was added, and the entire procedure was repeated 3 more times, pooling the organic layers together in a lipid-cleaned vial. Samples were then concentrated using a flash evaporator (Buchler Instruments, Fort Lee, NJ).
Lipid composition was determined using an Iatroscan Mark V TLC-FID, and silica-coated Chromarods, using a 3-step development method. Lipid extracts were applied to the silica rods and then focused into a narrow band using 100% acetone. In the first development system, rods were developed twice for 25 min and 20 min, respectively, in hexane:diethyl ether:formic acid (98.95:1:0.05). The second development system consisted of a 40-min development in hexane:diethyl ether:formic acid (79:20:1). The third development system involved 2 15-min developments in 100% acetone followed by two 10-min developments in chloroform:methanol:chloroform-extracted water (5:4:1). The rods were equilibrated in a constant humidity chamber before each development, and rods were dried and scanned after each development system. Peak data were analyzed using PeakSimple 3.72 (SRI Inc.). Standards from Sigma Chemicals (St. Louis, MO) were used to calibrate the Chromarods.
Lipid extracts were "transesterified" into fatty acid methyl esters (FAMEs) in 14% [BF.sub.3]/MeOH at 85[degrees]C for 1.5 h. FAME composition was determined using an HP 6890 Series GC FID equipped with a 7683 autosampler and a 30-m (0.25-[micro]m internal diameter) ZB wax + column (Phenomenex), using hydrogen as the carrier gas at 2 mL/min. Column temperature began at 65[degrees]C for 0.5 min then ramped up to 195[degrees]C at a rate of 40[degrees]C/min, and was held for 15 min. Temperature then ramped up to 220[degrees]C at a rate of 2[degrees]C/min, and was held for 3.25 min. Injector temperature started at 150[degrees]C and ramped up at a rate of 200[degrees]C/min until reaching a final temperature of 250[degrees]C, whereas the detector remained a constant 260[degrees]C. FA retention times were determined with Supelco's 37-component FAME mix (product no. 47885-U).
C and N content was determined using a Perkin Elmer Series II. Mussel samples were dried at 80[degrees]C, weighed, and then ground using mortar and pestle. Small amounts of mussel powder (1.9-2.1 rag) were placed in tin foil capsules and returned to the oven until they were run on the analyzer.
Amino acid content was determined using EZ:faast amino acid analysis kits (Phenomenex) and a Varian CP-3800 GC. The carrier gas was helium, with a constant flow of 1.5 mL/min. Oven temperature started at 110[degrees]C and ramped up to 320[degrees]C at a rate of 32[degrees]C/min. Split injection (1:15) of 2 [micro]L was used at 250[degrees]C, with a detector temperature of 320[degrees]C.
Significant differences were determined using I-way ANOVAs followed by Holm-Sidak tests to determine where those significances lay. Holm-Sidak tests can be used for both pairwise comparisons and a comparison versus a control group, and is more powerful than the Tukey and Bonferroni tests. Kruskal-Wallis 1-way ANOVA on ranks and a Dunn's method test were used when data failed the assumption of equal variance or normality. Statistical analysis was performed using SigmaStat 2.03 (SPSS Inc.). All results are given as mean [+ or -] SD.
There were no differences between replicate effluent tanks at the end of the experiment, so they were averaged to compare with the algae-fed tank. However, there were some small differences among the replicates for the intermediate dates (largest differences were SL, 0.4 cm; DW, 0.04 g; AFDW, 0.04 g; and CI, 1.4). When both effluent fed tanks were averaged and compared against the algae-fed tank, many differences were seen. Algae-fed mussels had a significantly higher DW, AFDW, SL, and CI at the end of the experiment than mussels fed fish effluent (Fig. 1). The only significant difference between the start and end of the experiment was a significantly higher SL for mussels fed algae.
There were no differences in C or N content between replicate effluent tanks at the end of the experiment, so they were averaged to compare against the algae tank. When the averaged effluent tanks were compared with the algae-fed tank, there were no significant differences. Protein content, calculated from N via a conversion factor of 5.8, of mussels fed algae and fish effluent increased from 454.2 [+ or -] 42.4 mg/g DW and 434.6 [+ or -] 36.0 mg/g DW at the start of the experiment to 591.7 [+ or -] 26.9 mg/g DW and 628.1 [+ or -] 17.3 mg/g DW, respectively. Effluent-fed mussels had a significantly larger protein content than algaefed mussels (Fig. 2).
There were no significant differences in total lipid content (measured in milligrams per gram WW) between mussels fed the 2 diets. However, lipid content of effluent-fed mussels decreased significantly throughout the experiment (Fig. 3).
There were no significant differences in lipid class content among replicate effluent tanks at the end of the experiment, so they were averaged and compared with the algae-fed tank. There were still no significant differences between mussels fed the 2 diets after the replicates were averaged (Fig. 4). There were some significant changes from the start of the experiment for mussels fed both diets. There was a decrease in HC, TAG, and ST for mussels fed both diets, as well as an increase in PL. Effluent-fed mussels also showed a significant decrease in their AMPL content.
In terms of total FA, content there were no differences between algae-fed and effluent-fed mussels at the end of the experiment. Total FA content (measured in milligrams per gram WW) for effluent-fed mussels did, however, decrease significantly throughout the experiment.
There was no difference in individual FA content (measured in milligrams per gram WW) among replicate effluent tanks, so they were averaged and compared with the algae-fed tank and the start of the experiment (Fig. 5). Mussels fed both diets decreased in their 14:0, 16:1[omega]7, 16:2[omega]4, 16:4[omega]1, and 20:5[omega]3 content, as well as increased in their 20:4[omega]6 content. Effluent-fed mussels also decreased in their 18:4[omega]3 and 21:5[omega]3 content, and increased in 17:1, the zooplankton markers 20:1[omega]9 and 22:1[omega]11, as well as the nonmethylene-interrupted fatty acids (NMIDs) 20:2a and 22:2b. The only other significant change for mussels fed algae was an increase in their 18:2[omega]6 content.
[FIGURE 1 OMITTED]
When the FA composition (measured in milligrams per gram WW) of mussels fed both diets were compared without the starting point, there were a few significant differences between diets. Algae-fed mussels had significantly more 18:2[omega]6 and 20:4[omega]6, as well as less 16:4[omega]1 than effluent-fed mussels (Fig. 5).
There were no significant differences in the amount of different FA groups (measured as a percentage of total FAs) among the replicates at the end of the experiment, so the effluent-fed tanks were averaged and compared with the algae-fed tanks and the starting period (Fig. 6). Mussels fed both diets increased significantly in the proportion of bacterial FAs between the beginning and the end of the experiment. Both diets decreased in the proportion of SFA, and algae-fed mussels decreased in the amount of MUFA, whereas effluent-fed mussels increased in MUFA. The proportion of [omega]3 FAs decreased for both diets, and algae-fed mussels increased in the proportion of PUFAs.
[FIGURE 2 OMITTED]
When the proportion of FA groups (measured as a percentage of total FAs) for mussels fed both diets was compared without the starting point, there were several significant differences (Fig. 6). Mussels fed effluent had significantly smaller proportions of PUFAs, [omega]3s, and [omega]6s than algae-fed mussels. Effluent-fed mussels also had a significantly larger proportion of MUFAs, zooplankton markers, and NMIDs than algae-fed mussels.
When the amino acid composition (measured as a percentage of total amino acids) of mussels in the replicate effluent tanks were averaged (no significant differences at end of experiment) and compared with the algae tank and the starting period, there were some significant changes in effluent-fed mussels (Fig. 7). Effluent-fed mussels were found to have decreased in their proportion of asparagine (ASN), glutamine (GLN), and hydroxylysine (HLY), whereas their proportion of alanine (ALA) increased throughout the experiment. Algae-fed mussels showed no significant changes in their amino acid composition (measured as a percentage of total amino acids) throughout the experiment.
[FIGURE 3 OMITTED]
When the amino acid composition (measured as a percentage of total amino acids) for mussels fed both diets were compared at the end of the experiment alone, only one significant difference was found. Mussels fed algae had a significantly larger proportion of the essential amino acid leucine (LEU) than effluent-fed mussels.
The proportion of FA groups for mussels at the beginning of the experiment was compared with that of mussels from Charles Arm and Fortune Harbour, NL (Alkanani et al. 2007) (Table 1). There were some significant differences; there was a smaller proportion of SFAs, PUFAs, and [omega]3s, as well as an increased proportion of MUFAs compared with cultured mussels.
At the end of the experiment, the proportions of FA groups for mussels fed both diets showed several significant differences when compared with mussels from Charles Arm and Fortune Harbour, NL (Table 1) (Alkanani et al. 2007). Both diets had significantly less SFAs, PUFAs, and m3 FAs, as well as a larger proportion of MUFAs.
The quantity (measured in milligrams per gram DW) of essential amino acids at the beginning of the experiment in mussels fed both diets was compared with that recorded for Mytilus galloprovincialis (Sengor et al. 2008) (Table 2). The amount of threonine (THR), phenylalanine (PHE), and lysine (LYS) was lower in mussels used for the current experiment than that of M. galloprovincialis.
[FIGURE 4 OMITTED]
At the end of the experiment, when the essential amino acid composition of mussels fed the 2 diets was compared with values for M. galloprovincialis (Sengor et al. 2008), there were still several apparent differences (Table 2). Again, the amounts of THR, PHE, and LYS were much higher in M. galloprovincialis. The LEU content of effluent-fed mussels was significantly lower than algae-fed mussels, which was closer to the recorded values for M. galloprovineialis.
Although no significant growth occurred (with the exception of SL) for mussels fed either algae or effluent, based on the significantly higher DW, AFDW, and CI values at the end of the experiment, algae-fed mussels performed better than effluent-fed mussels. This result indicates that effluent is either a lower quality food source or that mussels rejected a larger portion of the diet. It is important to note that algae-fed mussels were given a ration of 1.5% of their soft-tissue DW/day, whereas the amount of material available to effluent-fed mussels was calculated to be up to almost 10% of their soft-tissue DW/day in particles smaller than 70 [micro]m.
The decrease in C content for mussels fed both diets indicates that mussels may have been fed an inadequate ration. The increase in protein content between the start and the end of the experiment for mussels fed both diets indicates that some growth did occur. The larger protein content of effluent-fed mussels suggests that effluent has some potential as a diet for mussels. The C-to-N ratios for mussels in this experiment were comparable with the values recorded by Rodhouse et al. (1984). The significant decrease in the C-to-N ratio for all mussels suggests that both diets were rich in N.
The significant decrease in total lipid content (measured in milligrams per gram WW) in effluent-fed mussels, coupled with the lack of any significant decrease in algae-fed mussels, suggests that mussel performance was inferior when fed effluent.
Based on the lack of significant differences between mussels fed the 2 diets for lipid class composition, it appears that effluent did not affect mussel lipid composition negatively. Mussels fed both diets underwent a decrease in their TAG content, accompanied by an increase in their PL content throughout the experiment. This change from TAG to PL as the predominant lipid class is expected. The main lipid class in M. galloprovincialis during the spring and summer is TAG; however, during the autumn and winter, PL comprises the largest portion of lipids (Prato et al. 201[omega]. The mussels used for this experiment were collected during the spring, and the experiment concluded in the winter, which supports this trend.
Results for total FA content (measured in milligrams per gram WW) were similar to those for total lipid content (measured in milligrams per gram WW). Mussels fed effluent showed a significant decrease in their total FA content (measured in milligrams per gram WW), whereas algae-fed mussels did not. This again suggests that effluent is an inferior diet to algae.
Some of the observed differences in FA composition between the 2 diets at the end of the experiment were expected, such as the increased proportion of zooplankton markers in effluent-fed mussels (Fig. 6). This result supports the potential use of these markers as indicators of fish farm wastes. The increased amount of NMIDs in mussels fed effluent, and the increase in 22:2b for algae-fed mussels at the end of the experiment suggest that they were deficient in essential FAs (Fig. 6).
[FIGURE 5 OMITTED]
[FIGURE 6 OMITTED]
The higher level of the zooplankton marker supports the idea for their use as indicators of fish farm wastes; however, caution must be taken in the use of these markers as indicators of fish farm wastes because mussels are capable of ingesting mesozooplankton (Davenport et al. 2000). The essential FA 20:4[omega]6, which was higher in both algae-fed mussels and effluent-fed mussels, was present in small quantities in both the commercial shellfish diet used as well as the effluent. It is likely this FA was retained by the mussels selectively. Budge et al. (2001) reported levels of 20:4[omega]6 five times greater in mussels than their phytoplankton diet, and suggested mussels were capable of retaining this FA selectively.
Based on the changes in the proportions of FA groups between the start and end of the experiment, it is likely that mussels fed both diets were stressed nutritionally. The loss of SFA suggests that the amount fed to the mussels was insufficient, and that they were utilizing their SFA reserves for energy; the loss of [omega]3 FAs along with [omega]6 FAs suggests that mussels were deficient in essential FAs. Although it appears mussels fed both diets were stressed nutritionally, based on the significantly lower levels of PUFAs and [omega]3 FAs in effluent-fed mussels compared with algae-fed mussels, it is likely that effluent is an inferior quality diet in terms of FAs. The increase in bacterial FAs for mussels fed both diets was expected. The effluent was known to contain bacterial FAs, and the commercial shellfish diet likely accumulated bacteria with age.
[FIGURE 7 OMITTED]
It is possible that the elevated levels of bacterial FAs caused a decrease in the proportion of FAs (measured as a percentage of total FAs) for the other groups. The lower level of SFAs and [omega]3s in both diets compared with the recorded values further supports the idea that mussels fed both diets were stressed nutritionally.
The only significant difference in the amino composition between both diets was a larger amount of the essential amino acid LEU in algae-fed mussels as opposed to effluent-fed mussels both qualitatively (measured as a percentage of total amino acids) and quantitatively (measured in milligrams per gram DW). LEU is an important precursor to sterols (Meister 1965, Rosenthal et al. 1974). This fact could explain the lower ST levels in effluent-fed mussels compared with other mussels.
Arginine (ARG), which was reported to be present in M. galloprovincialis, was not found in any of the mussels analyzed in the current experiment. The reason no ARG was found is a result of the fact that ARG is not recoverable with the amino acid kit used in this experiment.
It is likely that the lower amount of PUFAs as well as essential FAs present in effluent-fed mussels will result in poor mussel performance. The increase in NMIDs for mussels fed effluent suggests that the diet was lacking essential FAs. However, there was an increase in protein content of effluent-fed mussels, and M. edulis has been reported to have increased growth rates when grown in an IMTA setting (Reid et al. 2008a). Although the FA composition of effluent was inferior, it is likely that it may be used as a replacement food source when a better diet is unavailable, as has been suggested by Stirling and Okumus (1995). This fact could explain the increased growth reported for mussels in an IMTA setting in the Bay of Fundy (Reid et al. 2008a).
The accumulation of zooplankton markers 20:1[omega]9 and 22:1[omega]1, which were present in the effluent and feed, in effluent-fed mussels supports the use of these FAs as markers of aquaculture waste. Further study needs to be undertaken to determine the full use of these FAs as markers of fish farm wastes.
We thank NSERC and the Department of Fisheries and Oceans Canada for funding this study, as well as the staff members at the Ocean Science Centre for all their help throughout the project.
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ADRIANUS BOTH, (1) * CHRISTOPHER C. PARRISH (1) AND RANDY W. PENNEY (2)
(1) Ocean Science Centre, Memorial University of Newfoundland, St. John's, NL, Canada A1C 5S7;
(2) Department of Fisheries and Oceans, Science, Oceans, and Environment Branch, St. John's, NL, Canada A1C 5X1
* Corresponding author. E-mail: email@example.com
TABLE 1. Sum of fatty acid groups (in percent total FA) for mussels fed algae and effluent at the end of the growth experiment in comparison with the fatty acid groups of Newfoundland mussels recorded by Alkanani et al. (2007). Alkanani et al. (2007) 2000 2001 Fatty acid n = 67 n = 75 [SIGMA]SFA 25.4 [+ or -] 1.8 (a) 23.6 [+ or -] 2.3 (b) [SIGMA]MUFA 14.5 [+ or -] 3.0 (a) 17.7 [+ or -] 4.1 (b) [SIGMA]PUFA 61.9 [+ or -] 3.0 (a) 60.8 [+ or -] 4.0 (a) [SIGMA][omega]3 47.8 [+ or -] 3.7 (a) 49.5 [+ or -] 3.5 (b) [SIGMA][omega]6 5.5 [+ or -] 0.8 (a) 6.4 [+ or -] 1.3 (b) [SIGMA]Zoo 5.0 [+ or -] 1.1 (a) 4.0 [+ or -] 2.4 (b) [SIGMA]NMID 7.3 [+ or -] 1.0 (a) 3.8 [+ or -] 1.7 (b) [SIGMA]PUFA/ 2.4 [+ or -] 0.2 2.6 [+ or -] 0.4 Growth Experiment Start Algae Fatty acid n = 10 n = 4 [SIGMA]SFA 21.6 [+ or -] 1.5 (c) 19.5 [+ or -] 0.3 (c) [SIGMA]MUFA 25.7 [+ or -] l.1 (c) 23.1 [+ or -] 2.0 (c) [SIGMA]PUFA 51.4 [+ or -] 1.9 (b) 54.6 [+ or -] 1.5 (b) [SIGMA][omega]3 43.0 [+ or -] 1.6 (c) 36.8 [+ or -] 1.9 (c) [SIGMA][omega]6 1.7 [+ or -] 0.2 (c) 10.5 [+ or -] 1.1 (d) [SIGMA]Zoo 1.8 [+ or -] 0.2 (c) 4.2 [+ or -] 0.3 (abc) [SIGMA]NMID 1.3 [+ or -] 0.2 (c) 6.6 [+ or -] 0.7 (a) [SIGMA]PUFA/ 2.4 [+ or -] 0.2 2.8 [+ or -] 0.1 Growth Experiment Effluent Fatty acid n = 4 [SIGMA]SFA 19.3 [+ or -] 0.5 (c) [SIGMA]MUFA 26.8 [+ or -] 1.9 (c) [SIGMA]PUFA 51.4 [+ or -] 2.1 (b) [SIGMA][omega]3 34.4 [+ or -] 1.3 (c) [SIGMA][omega]6 7.0 [+ or -] 0.7 (e) [SIGMA]Zoo 6.9 [+ or -] 0.4 (a) [SIGMA]NMID 9.2 [+ or -] 1.0 (d) [SIGMA]PUFA/ 2.7 [+ or -] 0.2 [SIGMA]SFA Groups with different letters are significantly different from each other. TABLE 2. Essential amino acid composition (in milligrams per gram DW) of mussels fed 2 different diets (algae and effluent) at the beginning of the experiment in comparison with that found by Sengor et al. (2008) for M. galloprovincialis. Sengor et al. Growth Experiment Amino (2008) M. Acid galloprovincialis Start Algae THR 26.59 7.3 [+ or -] 5.9 7.72 [+ or -] 10.13 VAL 24.44 19.8 [+ or -] 7.0 17.48 [+ or -] 11.88 MET 9.22 8.0 [+ or -] 3.1 7.40 [+ or -] 4.72 ILE 21.93 22.1 [+ or -] 5.7 19.49 [+ or -] 12.27 LEU 35.33 24.8 [+ or -] 25.7 32.98 [+ or -] 20.21 PHE 31.26 18.5 [+ or -] 6.1 15.76 [+ or -] 11.13 HIS 15.78 9.4 [+ or -] 9.9 6.35 [+ or -] 7.32 LYS 38.74 8.2 [+ or -] 10.5 3.25 [+ or -] 5.63 ARG 32.19 -- -- Growth Experiment Amino Acid Effluent THR 7.72 [+ or -] 2.90 VAL 12.56 [+ or -] 3.56 MET 6.02 [+ or -] 1.71 ILE 15.06 [+ or -] 4.04 LEU 7.82 [+ or -] 6.48 PHE 13.20 [+ or -] 3.22 HIS 9.86 [+ or -] 5.55 LYS 5.07 [+ or -] 7.87 ARG --
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