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Fish farming leads to pollution due to faces_ uneaten feed and

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Fish farming leads to pollution due to faces_ uneaten feed and Powered By Docstoc
					STABLE ISOTOPIC AND FATTY ACID EVIDENCE FOR
  UPTAKE OF FISH FARMING INDUCED ORGANIC
POLLUTANTS BY FILTER-FEEDING MUSSELS (PERNA
      VIRIDIS) IN A POLYCULTURE SYSTEM



Kevin Q F Gao1, S G Cheung1, G H Lin2,3; S P Chen2; Paul K S Shin1

1Department of Biology and Chemistry, City University of Hong Kong.
2Laboratory of Quantitative Vegetation Ecology, Institute of Botany, the

 Chinese Academy of Sciences.
3Department of Global Ecology, Carnegie Institution of Washington, USA.




                                                                     1
Introduction: Fish farming is an important economic
activity world-wide.




                                                  2
Introduction: Fish farming leads to pollution due
to uneaten feed, faeces and excretion.




                                                    3
Introduction: Bivalve mussels can filter particulate
matter in high efficiency.




                                                       4
Introduction: Polyculture, combining fish and
mussels, can achieve an environmental and
economic Win-Win solution.

                         Canadian Mussel Export Values (X106 US$)

                 25
                 20
  Export Value




                 15
                 10
                  5
                  0
                      1992   1993   1994   1995   1996   1997   1998   1999   2000   2001
                                                     Year



                                                                                            5
Introduction: Trophic markers

                  Stable Isotopes:
                  Changes in stable
                  isotope ratios (e.g.,
                  13C/12C and 15N/14N) are

                  predictable when matter
                  is transported along
                  trophic levels; they can
                  thus be used as markers
                  to trace matter flow: food
                  or pollutant sources and
                  fates.


                                               6
Introduction: Trophic markers


                       Fatty Acid Profile
                       Sink-specific and
                       conservative in
                       transportation and
                       transformation


                       Use of Multiple
                       Markers
                       Improve the accuracy
                       of determining source
                       and sink
                                          7
                   Objectives

1 To quantify the contribution of potential food sources
  to the mussel ration.



2 To evaluate the feasibility and capability of filter-
  feeding bivalves as biofilters for organic wastes from
  fish farming activities in a polyculture system.




                                                           8
Experimental site: Kau Sai marine fish
culture zone - a semi-enclosed bay




                                         9
                        Methods




1 Mussels transplanted to fish rafts and a reference site
  (without effects from fish farms).
                                                        10
                               Methods

2. Sampling from fish raft and reference site: mussels,
   particulate matter, fish feed and fish faeces after 3
   months in the field.

3. Sample analysis: 2 aliquots for all samples
  Aliquot 1 for stable isotope ratios (13C/12C and 15N/14N) with EA-IRMS;
  Aliquot 2 for fatty acid profiles with GC-FID


4. Data analysis:
   Comparison: Mussel tissue between fish raft and reference site with t-test.
   Isotope mixing model: Contribution of food sources to mussel tissue.
                                                                             11
   Principle Component Analysis (PCA) ordination: For fatty acid profiles.
Results: Stable Isotopes


                                              δ13C=[(13C/12C)smpl/ (13C/12C)std-1]X1000‰
                                              δ15N=[(15N/14N)smpl/ (15N/14N)std-1]X1000‰


 15

 10

  5           13
             δ C (‰)
  0
                                    15
 -5                                δ N (‰)

-10
                                 Reference site
-15                              Fish Raft
-20

-25


      Comparison of stable isotope values in mussel
                                                                               12
      tissue between fish raft and reference site
                Results: Stable Isotopes
           15
           14
                                                                 fish feces
                                                                                      Contributions of
           13                                                                         food sources to
           12                                               fish feed                 mussel ration:
           11
δ15N (‰)




           10                                                                         Based on isotope
                                          mussel
           9                                                                          mixing model,
           8
           7
                           POM                                                        POM: 68.3%;
           6                                                                          Fish feed: 27.5%;
           5
           -22.0   -21.0         -20.0    -19.0     -18.0      -17.0          -16.0   Fish faeces: 4.2%,
                                         δ13C (‰)




Dual isotope plot showing the food source of mussels at fish raft site

                                                                                                     13
Results: Overall Fatty Acid Profiles

Fatty Acids             MFR          MRS          PFR          PRS          FFD          FFC
Saturated Fatty Acids
11:0                    0.00         0.00         0.00         0.00         0.01±0.00    0.00
12:0                    0.00         0.01         0.00         0.00         0.17±0.02    0.00

14:0                    7.55±0.51    5.96±0.45    3.41±0.35    3.06±0.22    5.27±0.88    1.17±0.68

15:0                    0.90±0.22    0.71±0.03    0.24±0.02    0.42±0.09    0.72±0.06    0.23±0.01

16:0                    30.31±3.82   35.04±3.22   29.41±2.33   24.34±2.15   32.70±1.66   8.80±1.11

18:0                    10.59±0.78   7.53±0.46    2.48±0.30    4.26±0.48    9.16±1.10    7.72±0.35

17:0                    1.73±0.55    2.36±0.55    0.46±0.03    0.90±0.08    1.01±0.05    0.41±0.02

20:0                    0.97±0.08    0.55±0.06    0.49±0.07    0.00         0.83±0.07    0.75±0.06

21:0                    0.13±0.01    0.76±0.05    0.00         0.02         0.00         1.24±0.16

22:0                    0.00         0.00         0.24±0.01    0.00         0.00         0.00
subtotal                52.18±1.85   52.92±1.66   36.72±1.58   33.00±1.55   49.87±1.34   20.32±1.22


MFR-mussel of Fish Raft, MFS-Mussel of Ref. Site, PFR-POM of Fish Raft
PFS-POM of Ref. Site, FFD- Fish Feed, FFC-Fish faeces (meanSD, N=3-9)
                                                                                                      14
 Results: Overall Fatty Acid Profiles
Monounsaturated Fatty Acids
15:1n5                    0.00         0.00         0.84±0.03    1.79±0.01    0.04         0.00
17:1n7                    0.21±0.01    0.68±0.02    3.16±0.16    7.25±0.22    0.60±0.03    0.64±0.03
16:1n7                    10.65±0.68   8.47±0.56    17.76±1.23   17.73±1.33   8.28±1.02    8.67±0.89
18:1n9                    4.66±0.16    2.27±0.09    2.38±0.09    2.11±0.11    12.75±1.35   24.86±1.88
18:1n7                    3.85±0.11    3.52±0.15    7.67±0.22    9.78±0.36    3.89±0.11    3.55±0.15
20:1n9                    2.35±0.08    3.21±0.18    0.00         0.00         0.16±0.02    0.00
22:1n9                    0.45±0.05    0.61±0.03    0.00         0.00         0.00         0.39±0.05
subtotal                  22.16±1.55   18.75±1.63   31.80±2.15   38.66±2.30   25.71±2.10   38.11±1.59
Polyunsaturated Fatty Acids
18:2n6                    1.46±0.12    1.50±1.08    1.58±0.15    0.35±0.01    0.91±0.09    1.47±0.12
18:3n6                    0.20±0.01    0.00         0.00         0.00         0.05         0.28±0.01
20:2n6                    0.72±0.03    0.48±0.05    0.21±0.02    0.00         0.00         0.00
20:3n3                    0.14±0.01    0.20±0.01    0.21±0.01    0.00         0.00         0.00
20:4n6                    3.30±0.22    2.97±0.36    0.77±0.05    0.00         3.42±0.25    5.26±0.26
20:5n3                    8.24±0.22    12.21±1.23   16.06±1.25   14.37±1.36   7.00±0.79    7.74±0.88
22:2n6                    0.00         0.92±0.05    0.25±0.02    0.00         0.00         0.00
22:6n3                    11.59±0.98   10.04±0.88   12.41±1.23   13.62±1.33   13.07±1.56   26.84±2.32
subtotal                  25.66±1.52   28.32±2.21   31.48±3.32   28.34±2.35   24.45±2.01   41.59±3.32 15
      Results: Overall Fatty Acid Profiles
                                                            2
                                                                                                                                 Mussels at reference site
                                                      1.5
                                                                                                                          MFR
                                                            1
                                                                                                                          MRS
                                                      0.5
                                                                                                                          FFD    Mussels at fish raft
                                                            0
                                                  -0.5
   Fish feed, fish raft only                                -1
                                                  -1.5
                                                            -2
                                                              -1.2   -1        -0.8      -0.6   -0.4      -0.2        0




                                                 3 3
                                                 2 2                                                                            POM at reference site
                                                 1 1                                                                  MFR
                                                                                                                    MFR
                                PC2 (21.8%)
                                              PC2 (21.8%)




                                                                                                                      MRS
                                                                                                                    MRS
                                                 0 0
                                                                                                                    PFR
                                                                                                                      PFR        POM at fish raft
                                              -1 -1
                                                                                                                      PRS
                                                                                                                    PRS
                                              -2 -2
                                                                                                                      FFD
                                                                                                                    FFD
                                              -3 -3
Fish feces, fish raft only                                                                                            FFC
                                                                                                                    FFC
                                              -4 -4
                                              -5 -5
                                                   -1.5
                                                -1.5                    -0.5
                                                                     -0.5             0.50.5     1.51.5          2.52.5
                                                                                  PC1 (34.9%)
                                                                                PC1 (34.9%)



                               PCA ordination plot showing the Overall fatty                                                                                 16
                               acid profiles of mussels and their food sources
                                          Results: Single Fatty Acids




                                                                                                                                                          Sources identical
                                          45
                                                                                                                                          No effect
                                          40
                    Fatty acid conc (%)




                                          35
                                          30                                                                             Negative
                                          25                                                                             Effect
                                          20
                                                                  Positive Effect
                                          15
                                          10
                                          5
                                          0
                                                                 14:0              18:0 18:1n9                             20:5n3       16:0   18:1n7    22:6n3
Mussel, fish raft


                                          Fish feed, raft only


                                                                  POM, fish raft


                                                                                    POM, ref. site


                                                                                                     Mussel, ref site




                                                                                                                        Effects of fish feed fatty acids on mussel tissue


                                                                                                                                                                              17
                   Discussion
 1. The distinct stable isotopic and fatty acid signatures of
    different sources can be used as trophic markers to
    trace the transfer of organic matter along the food
    chains.
2. Combined evidence of stable isotopes and fatty acid
  profiles showed that filter-feeding mussels could
  directly consume the organic wastes derived from fish
  farming activities.
3. Eutrophic nitrogen and phosphorus could be fixed by
  mussel assimilation before the waste mineralization.
4. The mussels in a polyculture system can function as
  biofilters to reduce the nutrient released from uneaten
  fish feed and egested fish faeces in fish farms.      18
        Acknowledgements
• Agriculture, Fisheries and Conservation
  Department (AFCD) of Hong Kong
  government for funding;
• Group colleagues for sampling assistance;
• Technicians in Institute of Botany, the
  Chinese Academy of Sciences;
• Department technicians

                                         19
Thank You!


             20

				
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