The Potential of Mangroves in the Treatment of Shrimp Aquaculture Effluent on the Eastern Coast ...

148 Pages·2007·3.01 MB·English

The Potential of Mangroves in the Treatment of Shrimp Aquaculture Effluent
on the Eastern Coast of Thailand
7 Nina Fancy
B. Sc.( Horn), Queen's University, 1999
A Thesis Submitted in Partial Fulfillment of the
Requirements for the Degree of
MASTER OF SCIENCE
in the Department of Geography
O Nina Fancy, 2004
University of Victoria
AII rights reserved. This thesis may not be reproduced in whole or in part,
by photocopy or other means, without the permission of the author.
Supervisor: Dr. Mark Flaherty
ABSTRACT
This thesis examines the potential of low-cost, low-maintenance mangroves in the
treatment of nutrient-rich effluent originating from a shnmp f mon the coast of
Thailand's Chanthaburi province. The objective of this thesis is to identify the
environmental impact of shnmp aquaculture effluent and to determine if mangrove
wetlands can be used as effective biofiltration areas to remove significant quantities of
nitrate, ammonia and nitrite from shrimp wastewater. The study mangrove was found
to remove an average of 44.5% of nitrate, 46.6% of ammonia and 59.0% of nitrite
from shrimp effluent. The ratio of mangrove treatment area to shrimp f mre quired
to adequately treat daily effluxes of wastewater from shrimp f m sw as calculated to
.
be 1: 14. This ratio is significantly less spatially demanding than ratios calculated by
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P 0
previous researchers and reveals the potential of mangroves to be used as large-scale
wastewater treatment areas in shrimp-producing nations.
TABLE OF CONTENTS
..
..............................................................................................................
ABSTRACT
.1.1.
.......................................................................................
TABLE OF CONTENTS UI
...................................................................................................
LIST OF TABLES vi
..
................................................................................................
LIST OF FIGURES W..I.
..................................................................................
ACKNOWLEDGEMENTS WIN
.............................................................................................................
CHAPTER 1 1
....................................................................................................
INTRODUCTION 1
1.1 NATUREO F THE PROBLEM ................................................................................. 1
1.2 PURPOSE OF THE STUDY... ...............................................................................4.. .
1.3 THESIS OUTLINE ............................................................................................... -5
.............................................................................................................
CHAPTER 2 7
.......................................................................................................
BACKGROUND 7
2.1 GLOBALA QUACULTUTRREE ND.S.. .................................................................7.. .
2.2.1 Geographical ShiJi. ................................................................................1.3.
2.2.2System %iJi .............................................................................................. 16
2.3 MANAGEMENPTR ACTICE..S.. ........................................................................1..7.
2.3.1 Site Selection. ..........................................................................................1. 7
2.3.2P ond Preparation and Stocking ................................................................1 9
2.3.3 Feeding ...................................................................................................2. 0
2.3.4 Aeration and Water Exchange .................................................................2. 2
2.3.5 Harvesting ..............................................................................................2. 3
2.4 ENVIRONMENTALI MPACTS. ............................................................................. 23
2.4.1 Land Requirements .................................................................................2. 3
2.4.2 Water Supplies ........................................................................................2. 6
2.4.3 Chemical Discharge .................................................................................2 6
2.4.4 Organic Outputs ......................................................................................2 7
2.5 BESTM ANAGEMENT PRACTICES ......................................................................3 0
2.5.1 Planning and Management ......................................................................3. 1
2.5.2 Physical Techniques. .............................................................................. 3 1
2.5.3 Feed Related Practices. ...........................................................................3. 3
2.5.4 Policy Options ........................................................................................3. 4
2.5.5 Biological Practices ................................................................................. 35
2.6 SUMMAR.Y... ..................................................................................................3. 8
...........................................................................................................
CHAPTER 3 40
......................................................... .. ..........................
MANGROVE ECOLOGY 40
3.1 DEFINITION.. ................................................................................................4..0.
3.2 GEOGRAPHICADLI STRIBUTIO..N... .................................................................. 41
3.3 BIOL~GOYF MANGROVE..S.. ...........................................................................4. 2
3.3.1 Anatomy .................................................................................................4..2
3.3.2 Environmental Adaptations .....................................................................4. 4
3.3.3N utrient Dynamics ...................................................................................4 7
3.3.4A ssociated Hora and Fauna ..................................................................4..9
3.3.5 Natural and Anthropogenic Impacts .........................................................5 2
3.4 USESO F MANGROVE..S... ................................................................................. 54
3.4.1 Local Subsistence. ...................................................................................5. 4
3.4.2 Coastal Function ......................................................................................5 5
3.4.3 Tourism. ................................................................................................-.5. 6
3.4.4 Wastewater Filtration .............................................................................5. 6
3.5 CONSTRUCTED AND MODIFIED MANGROVES .................................................... 60
3.5.1 Design. ..................................................................................................6.. 0
3.5.2 Can Mangroves be Constructed?A Question of Environmental Feasibility
......................................................................................................................... 61
3.5.3 Economic Feasibility. ............................................................................... 64
3.6 SvMMARY .....................................................................................................6..6
...........................................................................................................
CHAP'lXR 4 67
..............................................................
STUDY AREA AND METHODOLOGY 67
4.1 REGIONAL CONTEX.T... .................................................................................... 67
4.2 FARMA REA. ..................................................................................................- 70
4.3 MANGROVDEE SCRIPTIO..N... ..........................................................................7. 4
4.4 EXPERTMENTDAELS IGN.. ...............................................................................7..6
4.5 DATAC OLLECTIOONV ERVIEW... ....................................................................7. 7
4.5.1 Pre-TreatPnent Samples: Mondays ............................................................7 7
4.5.2 Post-Treatment Samples: Wednesdays ....................................................7. 8
4.6 INSTRUMENTATION AND LABORATORAYN ALYSES ...........................................7 9
4.7 LIMITATION..S.. .............................................................................................8..0
...........................................................................................................
CHAPTER 5 82
.............................................................................
RESULTS AND DISCUSSION 82
5.1 SAMPLEI D ~ C A T I O...N.... .........................................................................8. 2
5.2 PH AND RAWFALLDAT.A.. ...........................................................................8..3.
5.3 BOD ANALYSI.S.. ..........................................................................................8. 6
5.4 PJUSE ANALYSIS .............................................................................................8 9
5.5 PRE-TREATMENT DATA:E FFLUENSTA MPLE.S.. .............................................. -92
5.6 PRE-TREATMENT DATA:M ANGROV.E.. ...........................................................9. 7
5.7 POST-TREATMENDTA TA. ...............................................................................9. 8
5.8 COMPARISOONF PRE-TREATMENT AND POST-~XI~ATMNEITNRTO GEN DATA. . 103
5.8.1 Nitrate. ...................................................................................................1 04
5.8.2A mmonia ...............................................................................................I.0 7
5.8.3 Nitrite .................................................................................................1 08
5.9 PERCENTR EMOVALO F NUTRIENT..S.. ............................................................1 09
5.10 NITROGENLO ADINGO F THE COASTO F CHANTHABUR..I. ..............................1 11
5.1 1 L~ATIONANSD FUTURE RESEARCHN EEDS. .............................................1 13
5.12 MANAGEMENIMTP LICATIONS ......................................................................1 16
5.12.1.M angrove to Shrimp Pond Ratio ........................................................1. 16
5.12.2R ecirculation. ......................................................................................I.2 1
5.12.3 Global Impacts ..................................................................................... 122
5.13 SVMMAR..Y... ............................................................................................1..2 3
.........................................................................................................
CHAPTER 6 125
.....................................................................................................
CONCLUSION 125
6.1 SUMMARY ..................................................................................................... 125
6.2 MAJORR ESEARCHFI NDINGS.. ........................................................................1 26
6.3 FUTURE RESEARCHD IRECTION.S.. ................................................................. 127
.....................................................................................................
REFERENCES 129
LIST OF TABLES
Table 2.1 : Comparison of extensive, semi-intensive and intensive shrimp farms in
Thailand.. ................................................................,. ... ............... 18
Table 2.2: Common chemical and biological compounds used in intensive shrimp
culture in Thailand. ........................................................................ 21
Table 2.3: Optimum water quality parameters for culture of P. monodon... ........... 24
Table 2.4: Concentrations of key nutrients in shrimp farm effluent from an
intensively managed shrimp pond in Thailand.. .......................................2 9
Table 2.5: Regulations for shrimp farming issued by the Thai government,
November 1991... ..........................................................................- 36
Table 3.1 : Examples of mangrove loss in Asia and Oceania.. ............................ 43
Table 4.1 : Land use practices along the coast of Chanthaburi in 1991... ............... 70
Table 5.1: Mann-Whitney tests to detect differences between nitrate, ammonia
and nitrite concentrations in the 2 distinct phases ...................................... 91
Table 5.2: Pretreatment mean concentrations of nitrate, ammonia and nitrite in
effluent. ...................................................................................-.9. 3
Table 5.3: Mean concentrations of nitrate, ammonia and nitrite during weeks
1-4 and weeks 5-8.. ......................................................................... 93
Table 5.4: Mann-Whitney test to detect if differences in nitrate, nitrite and
ammonia concentrations exist between weeks 1-4 and 5-8.. ......................... 93
Table 5.5: Comparison of mean nitrate, ammonia and nitrite concentrations
in eMuent in this study (averaged over 8 weeks). ....................................... 96
Table 5.6: Post-treatment mean concentrations of nitrate, ammonia and nitrite
in the mangrove... ........................................................................- 100
Table 5.7: Concentration of nitrate, ammonia and nitrite in well samples... .......... lo0
Table 5.8: Comparison of pre-treatment values of nitrate, ammonia and nitrite
compared to the upper bound of the 95% confidence interval of
post-treatment values.. ...................................................................1 06
vii
LIST OF FIGURES
Figure 2.1: Aquaculture production of shrimp (by weight) in 19 98 .......................... 10
Figure 2.2. Aquaculture production (by weight) of P.monodon in Thailand ...........1 5
Figure 3.1. Photo of Avicennia marina pneumatophores. ................................. 46
Figure 3.2. Simplified nitrogen cycle in mangrove ecosystems. ........................ SO
Figure 4.1 : Map of Chanthaburi with approximate location of the study site. .......... 68
Figure 4.2. Average monthly temperature in Chanthaburi, Thailand ....................6 9
Figure 4.3. Average monthly rainfall in Chanthaburi, Thailand ..........................6 9
Figure 4.4. Layout of the shrimp farm and mangrove study site. ........................7 2
Figure 4.5: Magnified view of the modified mangrove area with approximate
location of the submersible pump ........................................................ 75
Figure 5.1. Field schedule with sample week and day identification .................... 84
Figure 5.2. pH values for pre and post-treatment samples .................................8 5
Figure 5.3. BOD2 data for pre-treatment effluent samples ................................ 87
Figure 5.4: Residual Dissolved Oxygen concentration after 2-day incubation
period ......................................................................................... 87
Figure 5.5. Average nitrate concentrations for effluent and mangrove samples ........9 9
Figure 5.6. Average ammonia concentrations for effluent and mangrove samples ....9 9
Figure 5.7. Average nitrite concentrations for effluent and mangrove samples .........9 9
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Figure 5.8: Concentration values for all pre-treatment samples plotted in
ascending order. .........................................................................-.1 05
Figure 5.9: Percent of nitrate, ammonia and nitrite removed from effluent by the
treatment mangrove throughout the field season ...................................... 110
...
Vlll
ACKNOWLEDGEMENTS
There are a number of people I would like to thank for making this research
possible. Thank you to CIDA for providing the funding for the field research portion
of this thesis. My warmest thanks also goes to my supervisor, Dr. Mark Flaherty
whose support throughout this degree has been invaluable. To my committee, your
knowledge and insight enabled me to delve further into my results to uncover the true
value of my research.
There are a few people without whom both my sanity and smile would have been
lost long ago. Michey, your endless laughter, your overwhelming understanding of all
my quirks, your cleverness and your adoption into the Fancy Family has made you the
better halfmanx I never thought I'd find. Without you Operation Man-Grove and
Operation My-Probe would have been a disastra rather than a pleasure. I can't thank
you enough for getting me through this! Krissy - you always know how to make the
whole world seem right again, even when I don't know whaaahappened and the
walskis crumble, thanks sweets! Curls, ahhh, sweet Curls, the autumn leaves blow in
the wind and I wonder what we all would have done without the brains of the
operation! Billy, my friend through thick and thm, armed with bevvies and a huge
smile at every turn of life - cheers to the next chapter. And to J-cks, my muse for
everything un-academic and my reminder that magic truly exists. To my family - no
words exist for the thanks I'd like to express. You have all been my rock when I
wavered in the wind, you've shown me the paths and walked beside me as I choose
my way, even when I make wrong turns. I thank you not just for your support
throughout this degree, but for your unfaltering knowledge, wisdom and love. Thanks
for always believing in me and making me realize I can move mountains - I just have
to put a little heart into it!
CHAPTER 1
INTRODUCTION
1.1 Nature of the Problem
Aquaculture has traditionally been viewed as a low-impact technique for rearing
aquatic species with little alteration to their natural environments (Csavas 1993). The
ever-increasing demand for aquatic protein on international markets, coupled with
declining global finfish and shellfish stocks, however, has transformed aquaculture
from a low-intensity farming practice, capable of sustaining small rural communities,
into a thriving industry contributing over 27% to world fisheries production ( FA0
2002). The economic success of the recent boom in aquaculture has brought much
needed foreign exchange and employment opportunities into previously impoverished
areas (Flaherty and Kamajanakesom 1995). Unfortunately, as with many industries
that expand at such a high rate, this so-called "Blue Revolution" does not come
without some negative political, social and, of most concern, environmental
repercussions (Moss et al. 2001).
Yields obtained from low-impact, extensive practices are minimal and farm
expansion is neither spatially nor financially feasible (Hopkins et al. 1995b, Nunes
and Parsons 1999). In order to increase production, given land scarcity and monetary
constraints, intensive high-input farming techniques were developed. However, the
degree of nahual system manipulation necessary for intensively rearing aquatic
species renders this farming technique unsuitable for many animals sensitive to
environmental fluctuations (Folke and Kautsky 1992, Boyd 2001). Of the aquatic
species harvested for human consumption, shrimp appear to be the most resilient to
variations in environmental conditions and are also a highly profitable commodity,
making them one of the most commonly intensively farmed aquatic animals (FA0
2002).
The widespread adoption of intensive shrimp farming has provided financial
benefits to numerous communities. However, when environmental degradation is
considered, the true costs of such high input practices are generally much greater than
their monetary benefits (Folke and Kautsky 1992, Naylor et aZ. 2000). The increased
popularity of intensive shrimp aquaculture, along with a lack of environmental
regulations in most of the producer nations, allowed for the establishment of high
input f m sa djacent to sensitive tropical coastlines and estuarine waters (De Silva
1998). Although many of the effects of intensive practices were initially unknown,
the environmental impacts of shrimp farming have since been extensively researched
and include mangrove destruction, the introduction of exotic species and land
salinisation as common side-effects of these techniques (Pbz-Osuna 2000, Dierberg
and Kiattisimkul 1996). These impacts all degrade the ecological integrity of
surrounding ecosystems to varying degrees. The most serious of these result from the
large effluxes of untreated nutrient-rich waters released into neighbouring waters
(Dierberg and Kiattisimkul 1996).
Shrimp farm effluent contains high concentrations of organic compounds
containing nitrogen and phosphorus (Funge-Smith and Briggs 1998). The continuous
draining of such eutrophic waste into surrounding irrigation canals and coastal waters
is extremely handid to the health of proximal ecosystems. Eutrophication of
receiving waters is of primary concern where shrimp farms are densely situated along
coastlines that serve as nursery and breeding grounds for numerous marine species.
This is most prevalent in Thailand, the largest producer of farm-reared black tiger
shrimp (Penaeus monodon) in the world (Kongkeo 1994, FA0 2002).