Possible ecological impacts caused by sea cage farm activities on surrounding coral reef ecosystem in nha trang bay, vietnam

MINISTRY OF EDUCATION AND TRAINING NHA TRANG UNIVERSITY ___________________________ NGUYEN THU HIEN POSSIBLE ECOLOGICAL IMPACTS CAUSED BY SEA-CAGE FARM ACTIVITIES ON SURROUNDING CORAL R

MINISTRY OF EDUCATION AND TRAINING

NHA TRANG UNIVERSITY _

NGUYEN THU HIEN

POSSIBLE ECOLOGICAL IMPACTS CAUSED BY SEA-CAGE FARM ACTIVITIES ON SURROUNDING CORAL REEF ECOSYSTEM IN NHA TRANG BAY, VIETNAM

MASTER THESIS

KHANH HOA – 2017

MINISTRY OF EDUCATION AND TRAINING

NHA TRANG UNIVERSITY _

NGUYEN THU HIEN

POSSIBLE ECOLOGICAL IMPACTS CAUSED BY SEA-CAGE FARM ACTIVITIES ON SURROUNDING CORAL REEF ECOSYSTEM IN NHA TRANG BAY, VIETNAM

MASTER THESIS

Climate Change

Topic allocation Decision: 772/QD-DHNT, dated 20/9/2016

Decision on establishing the Committee:

Suppervisors:

Dr Nguyen Lam Anh

Chairman:

Associate Prof Ngo Dang Nghia

Faculty of Gradute Studies: Faculty of Economics

KHANH HOA – 2017

Nha Trang, 03, May, 2017

(Signature and full name)

Nguyen Thu Hien

ACKNOWLEDGMENT

I wish to express my sincere appreciation to the following organizations and persons for their invaluable support, help and encouragement to me in conducting this study:

The Norwegian Programme for Capacity Development in Higher Education and Research for Development (Noherd) for giving me the opportunity to study and conduct this master thesis on Marine Ecosystem based Management and Climate Change

The Faculty of Economics and Institute of Marine science and Fishing Technonogy in Nha Trang University; Section of Marine Ecology, Institute of Oceanography of Nha Trang; Nha Trang Institute of Technology Research and Application for supporting facilities, materials, apparatuses, equipment for helping and giving best conditions for me to finish my thesis

My special thanks go to Prof Sigurd Stefansson, Prof Henrik Glenner and Dr Lam Anh for the continuous support of my Master study and research, for their patience, motivation, enthusiasm, and immense knowledge Their guidance helped me in all the time of research and writing of this thesis

To Dr Hoang Trung Du and Dr Pham Trung San for their guidance and invaluable suggestions, their support, encouragement and flexibility, often beyond his call

of responsibility Furthermore, I wish to express my profound gratitude for their stimulating comments and discussions, their ability to positively give and receive information, their openness towards freedom of expression, choices and their monumental patience shown during the research program Actually, their enthusiasm and integral view

on research has made such a deep impression on me

To all members of Section of Marine Ecology, Institute of Oceanography of Nha Trang and my colleagues in Corrosion Research Department, Nha Trang Institute of Technology Research and Application for their cooperation, for all the kindness and friendship

Last but not the least, I would like to thank my family: my parents, my husband

and to my brothers and sisters for supporting me spiritually throughout writing this thesis

Thank you!

Nha Trang, 03, May, 2017

(Signature and full name)

Nguyen Thu Hien

TABLE OF CONTENTS

UNDERTAKING i

ACKNOWLEDGMENT ii

TABLE OF CONTENTS iv

LIST OF SYMBOLS vi

LIST OF ABBREVIATION vii

LIST OF TABLES viii

LIST OF FIGURES ix

ABSTRACT x

INTRODUCTION 1

Research objectives 3

Research contents 3

Hypotheses 3

Research questions 4

CHAPTER 1: LITERATURE REVIEW 5

1.1 OVERVIEW OF RESEARCH SITUATION ABROAD 5

1.1.1 Aquaculture activities 5

1.1.2 The impacts of aquaculture activities to environment and ecosystems 6

1.2 OVERVIEW OF DOMESTIC RESEARCH SITUATION 9

1.2.1 Aquaculture activities 9

1.2.1.1 Aquaculture operations in South Central coastal provinces 9

1.2.1.2 Aquaculture activities in Khanh Hoa province 10

1.2.2 The impacts of aquaculture activities to environment and ecosystems 16

1.3 THE IMPACTS OF EUTROPHICATION AND SEDIMENTATION ON CORAL REEF 18

1.4 CLIMATE CHANGE FROM THE PERSPECTIVE OF STUDYING THE ANTHROPOGENIC IMPACTS BY AQUACULTURE 20

CHAPTER 2 MATERIALS AND METHODOLOGY 22

2.1 DATA SOURCE USED 22

2.2 SAMPLING STRATEGIES 22

2.2.1 Study sites and sampling design 22

2.2.2 Sediment sampling 23

2.2.3 Conducting field experiments (coral cross-transplanted) 24

2.3 THE METHOD OF SAMPLES ANALYZED 25

2.3.1 Sediment samples 25

2.3.2 Coral samples analysis: 27

2.4 DATA PROCESSING METHODS 28

CHAPTER 3 RESULTS AND DISCUSSION 29

3.1 THE ASSESSMENT OF EUTROPHICATION IN DIFFERENT SITES 29

3.2 SEDIMENT CHARACTERISTIC AND SEDIMENT QUALITY 32

3.4 FFIELD EXPERIMENT – CORAL TRANSPLANTATION 38

CHAPTER 4: CONCLUSION AND RECOMMENDATION 41

REFERENCES 43 APPENDICES

LIST OF SYMBOLS

NT1, NT2, NT3: Near-field farming sites

NT4, NT6: Mid-filed farming sites (1.2km from the breeding areas)

NT5, NT7: Far-field farming sites

M2: Weight of samples and aluminum cup dried in an oven for 48 hours

at 80oC M3: Weight of samples after mashed, restored in other aluminum cup M4: Weight of samples after burned at 550oC in 4 hours

ChA: Chlorophyll-a concentration, as µg/l

aD%O: Oxygen as absolute % deviation from saturation

L: The amount of Nitrogen or Phosporous discharged into the

environment (kg/m2)

Fc /FCR: Feed conversion ratio

Cfeed: The content of N/P in feed (%)

Cfish: The content of N/P in feed inside the lobster, fish meat (%)

LIST OF ABBREVIATION

IPCC: Intergovernmental Panel on Climate Change

LC50: The lethal concentration required to kill 50% of the population NCAR: Anthropologists at National Center for Atmospheric Research

AAA: American Anthropological Association

DIN: Dissolved inorganic nitrogen

DIP: Dissolved inorganic phosphorus

TOM: Total Organic Matter

TOC: Total Organic Carbon

GF/F: The grade of Whatman paper used for filting extremely fine precipitates

such as protein, nucleic acids, or serum precipitates HOBO: The device used for measuring air temperature, relative humidity, dew

point, rainfall, soil moisture, solar radiation, wind speed and direction, barometric pressure, and more

TN: Total Nitrogen

TP: Total Phosphorus

CHNO-S: Elemental analyser for analyzing Carbon, Hydrogen, Nitrogen, Sulfur and

Oxygen content TSM: Total suspended matter

FCR: Feed conversion ratio

LIST OF TABLES

Table 1.1: Production of main species groups of fish from marine and coastal aquaculture

in 2014 5

Table 1.2: Current status of fisheries and aquaculture in the South Central Province from 2009 to 2013 9

Table 1.3: Current status of fisheries and aquaculture in Khanh Hoa Province from 2009 to 2014 10

Table 1.4 Summary of the commonly cultured species in Khanh Hoa Province 13

Table 1.5: The development of lobster farming in Nha Trang bay from 2005 to 2011 15

Table 3.1: The nutrient concentration in Nha Trang Bay in two sampling periods 29

Table 3.2: The Estimation of waste output from lobster cage farm activities in 2015 37

LIST OF FIGURES

Figure 1.1: Distribution of five cultured areas in Nha Trang bay 15

Figure 2.1: Map of sampling sites in the cage farming areas of Nha Trang Bay 23

Figure 2.2: Sediment Grab for sampling sediment samples 24

Figure 2.3: Diagram of sediment traps deployed in the transects 24

Figure 2.4: Coral transplantation sites Red circle: near-field of cage farming area (major affected by cage farming) Green circle: far-field of cage farming area (less affected area) 25

Fig 3.1: The nutrient concentration in Nha Trang Bay in two sampling periods 30

Fig 3.2: TRIX Index in May 2015 31

Fig 3.3: TRIX Index in April 2016 31

Fig 3.4: TOM (%) in surface layer sediment at different sites in 2015 and 2016 33

Fig 3.5: TOC (mg/kg) in surface layer sediment at different sites in 2015 and 2016 33

Fig 3.6: The distribution of TN and TP in surface-layered sediment at different sites in two sampling times 2015 and 2016 35

Fiure 3.7: Sedimentation rates in the study sites of Nha Trang Bay in 2015 and 2016 36

Figure 3.8: The distribution of TOM in sediment traps at the study sites of Nha Trang Bay in May, 2015 and 2016 36

Figure 3.9: the different experiment of coral transplantation in clearly site (2) and near-by the fish farm (1) are in Hon Mot Island Nha Trang bay during 31days 39

Fig 3.10a: The results after one month of experiment at far-field site: (A): At the beginning of experiment (first day); (B) after 31 days 39

Fig 3.10b: The results after one month of experiment at near-field site: (A): At the beginning of experiment (first day); (B) after 31 days 40

Figure 3.11: The results of zooxanthella densities at the staring experimental time and after a month in Hon Mot Island 40

ABSTRACT

Nha Trang Bay is located in the area of Nha Trang City, Khanh Hoa Province, the area of south-central coast, Vietnam It is suitable for the travelling and anchoring of vessels together with surface aquaculture (cages) However, the environment in Nha Trang Bay is suffering serious degradation due to overloading of farming density

Based on the survey and analyzing data of VAST05.03/15-16 project and the results of experiments on sediment samples in Nha Trang Bay We have assessed the impact of sea-cage culture activities on the degradation of coastal waters The results showed that the nitrogen content in the high nutrient (N) in the study area: the average content of dissolved inorganic nitrogen (DIN) was 177.4 μg/l in 2015 and 141.7 μg/l in

2016 At most survey sites The N:P ratios were larger than 16, it has been shown that phosphorus salts may be the limited nutritional factor in these coastal waters TRIX indexs were recorded for both the surface and bottom water bodies in the range of 5-6, which indicated that the level of eutrophication was high and water quality is not good Especially in cage culture areas and surroundings

The TOC levels in the analyzed sediments were in the range of sediments with low organic carbon level Research also suggests that sediment rates ranged from 1.24 to 3.03

mg cm-2d-1 may not affect the development and recruitment of coral reefs surrounded The estimation of nitrogen and phosphorus concentrations discharged into the environment, with a yield of 0.389 kg/m2 in 2015, were 58.48 tonnes and 29.79 tonnes, respectively for

1 ton of commercial lobster

The coral transplantation experiments indicated that the amounts of mucus produced per algae was lower but the total amount of algal blooms is higher This study confirms the negative effects that nutrient levels have on corals themselves The increasingly development of human activities that are threatened by anthropogenic pollutants Sea cage farming is one of the stressors negatively impacting coral reefs by being point sources of nutrients and other effluents

Key word: Eutrophication, TRIX index, nutrients, coral reef, and sea-cage farm

INTRODUCTION

Nha Trang Bay is located in the area of Nha Trang City, Khanh Hoa Province, the area of south-central coast, Vietnam It is listed as one of 29 most beautiful bays in the world, with its islands and white sand beaches This place has diverse resources and landscapes with specific ecological characteristics of the tropics, including many marshes, bays, estuaries etc It is suitable for the travelling and anchoring of vessels together with surface aquaculture (cages) Its marine surface area is about 40,000 hectares, adjacent to offshore waters, where has the combination of ocean currents, upwelling zones Therefore, Nha Trang Bay often receives multiple streams of floating and migratory fish

In addition, it has internationally important coral reefs with the highest coral biodiversity recorded in Vietnam Despite the pressure from economic development, Nha Trang Bay retains some of the very few intact coral reefs in Vietnam Coral reef ecosystems have more than 222 species of reef fish, 350 species of coral (40% of the coral reef in the world), 120 species of mollusks, 70 crustaceans, 30 species of echinoderms, 70 species of seaweed and 7 species sea grass etc The environment in Nha Trang Bay is suffering serious degradation due to overloading of farming density From

2009 to present Nha Trang Bay experienced strong growth in the aquaculture industry Water surface area of aquaculture in 2015 was 5.8 thousand ha, has increase of 0.9 thousand ha compared to 2009 Aquaculture output increased 5 times from 2825 tones (2009) to 14 270 tones (2015) (The General Statistics Office, 2015) Moreover, the aquaculture was spontaneous, fragmented and not planned; the disputes of farming grounds always caused chaos which made the environmental situation worsening (Trang,

et al., 2009) Organic wastes from aquaculture including leftover feed, settling, wastes from living activities, chemicals… have caused numerous environmental problems (Du,

et al., 2006) The amount of nutrients as well as organic matter from uneaten feed (only 17% by weight of feed supply is converted to biomass) was directly discharged into the environment (Hoang Trung Du, 2006) It leads to heavily contaminated water bodies, eutrophication and increasing aquatic diseases to livestock, coral reefs and benthic fauna The coral communities in the bay have significantly deteriorated compared to the results

of the first hydro-biological surveys in the early 1980s By the beginning of the 21stcentury, the average coral cover in the bay was less than 30% (Tkachenko, 2015)

Climate change is intensifying the symptoms of eutrophication and sediment on coral reefs However, eutrophication can also conversely promote climate change (Moss

et al., 2011) Eutrophication may lead to lower proportionate dependence on imported organic matter and greater autotrophic fixation of carbon dioxide; nonetheless, it also leads to increased absolute production and respiration, greater release of methane from deoxygenated waters and sediments, (Bastviken et al 2008, 2011), and more nitrous oxide from denitrification (Huttunen et al 2003) Both the latter gases are more effective greenhouse gases than carbon dioxide (Moss et al., 2011)

Different global climate change scenarios can manifest themselves by varying effects on different components of the ecosystem These results may be difficult to detect because of the effects of human-induced changes but are now covered by the inherent

"background" of natural systems (Sanderson et al Halpern et al., 2008) As in the sense of human-induced tensions, we can not completely differentiate between the global climate change aspect and the anthropological aspect of global change for eutrophication Because

of the overlap in pressures and consequences (Rabalais, NN, et al.)

One of the biggest threats to coral reef health is the direct human impacts of eutrophication and sedimentation from concentrated aquaculture Because in coastal areas, the effects of climate change on corals are unclear, mainly related to abnormal rainfall causing floods and high suspended solids into the coastal zone While human impacts on the climate of this period are more prevalent due to changes in the natural processes (IPCC, 2007) Nowadays, the problem is much larger in scale (Wilkinson 1999) 50-70% of coral reefs are directly affected by anthropogenic global climate change (Hoegh-Guldberg 1999)

Recent studies on the impacts of eutrophication and sediment from cage aquaculture on coral reefs have remained modest and have only focused on the effects of sediment pollution in the mangroves as well as tidal flats (Quy, et al., 2011; Tue, 2011) The lack of research data about the impacts of cage aquaculture on coral reef makes decision makers suffer troubles in marine spatial planning for aquaculture, tourism and

conservation (Yee, et al., 2015) Therefore, the study of sediment impacts caused by cage farm activities on coral reef in Nha Trang Bay is a pressing need Recognize the

sea-essential of the problems I carry out the study about “Possible ecological impacts caused

by sea-cage farm activities on surrounding coral reef ecosystem in Nha Trang Bay, Vietnam”

- Determine sediment characteristic and sediment quality at 7 different sites

in Nha Trang Bay, thereby assessing sediment quality and sediment contamination level

- Estimation of Nitrogen/Phosphorous contents from the the cages discharged into the environment

- Carry out field experiment - coral transplantation to determine the effects of sedimentation and eutrophication on coral reefs in the bay

Hypotheses

- Impacts of from sea cage activities on sediment bottom, especially from uneaten feed and faeces causes severe pollution in water and sediment quality in cage farming area and vicinity

- Exposure to elevated sedimentation for repeated or prolonged periods of time has lead to reduced coral recovered and recruitment, or declining biodiversity due to the loss of sensitive taxa

CHAPTER 1: LITERATURE REVIEW 1.1 OVERVIEW OF RESEARCH SITUATION ABROAD

1.1.1 Aquaculture activities

Fish is farmed for many thousands of years However, the farming of marine species is more demanding than freshwater fish Aquaculture in the past and the present periods these kinds of omnivores or shellfish have provided a source of easy and reliable harvesting of food (Kaiser, et al., 2011) Cage aquaculture is increasing worldwide, with the cage aquaculture of high value finfish the fastest growing sector (Delgado, et al., 2003) predicted that fish consumption in developing countries will rise by 57%, from 62.7 million metric tons in 1997 to 98.6 million in 2020, and cage culture is expected to play a important role in meeting the demand (Tacon, et al., 2007)

In Asia, more than 95% of marine finfish aquaculture is in cages, (De Silva, et al., 2007) The production of the Pacific region and Asia in 2010 reached 53.1 million tonnes, accounting for 89% global production (59.9 million tonnes) (Funge-Smith, et al., 2012) The top three marine and coastal aquaculture regions in 2014 were Asia, Europe and Americas and their production were accounting for 81.2%, 9.2% and 8.3% of world production, respectively (FAO, 2016)

Table 1.1: Production of main species groups of fish from marine and coastal aquaculture

1.1.2 The impacts of aquaculture activities to environment and ecosystems

- Redundant feed direct discharged into the environment

The small-scale aquaculture in Asia is currently constrained by a number of factors including inadequate access to finance, a lack of technical innovations, an absence of feed formulation and processing knowledge, and training Therefore, it often encounters with redundant feed and which led to decrease productivity and increase cost (Shipton, et al., 2013) Wastes arised from feeds includes a solid particulate fraction comprising uneaten and undigested feed and faeces, and a dissolved fraction comprising metabolic by-products, urea, phosphate and principally ammonia (Bergheim, et al., 2003) The quality and quantity of the effluent will vary depending on culture species, the production system, and the physical and nutritional characteristics of the feed (Shipton, et al., 2013) For industrial culture ponds, wastes in the pond can hold up to 45% nitrogen and 22% of other organic substances.(Pearson, et al., 1978)

- Organic wastes deposited in sediment

Organic wates generated in aquaculture operation comprise formulated feed and faeces (including urine) and waste (unconsumed) feed (Cho, et al., 1998) Wastes and faeces can be a significant contributor of organic carbon to sediments, approximately 20%

carbon in feed is transformed into faece (Silvert, 1994) Organic pollutants deposited in the sediment will initially provide food to the bottom ecosystem and stimulate the production of macro-fauna and aerobic bacteria When oxygen demand for bottoms exceeds the available amount, aerobic processes are converted to anaerobic processes, reducing and/or altering macro-fauna The bottom becomes oxygen-deficient and can be sterile by gases such as methane and hydrogen sulphide Sedimention rates from 0.1 to 1.0 gC/m2/d (Hargrave, 1985) and those figures for fish faeces and waste feed are lager than 1.0 gC/m2/d cam caused significant organic contamination (Wildish, et al., 2004) It will reduce the flow underneath the fish cages and increases the amount of organic waste

to the seabed; increases physiological stress on the aquatic community under the cages and led to a decrease in biodiversity or, in extreme cases completely remove large organisms living on the bottom, which is then replaced by bacteria (Pearson, et al., 1978)

A portion of solid particles will be brought to downstream due to the tide, gradually reduce organic pollution around the cage Farmers also try to reduce the amount

of leftover feed and move the cages regularly in order to ecosystems undergo restoration However, a few closed waters are overloaded with farms, because it is the place where concentrate adverse impacts of cage culture, eliminating the possibility of solving the problem by moving the cages These systems are reducing dissolved oxygen levels in the water column, increasing the stress levels for fish, susceptible to outbreaks The connection of cages and ropes to the seabed will increase the friction and thus it causes flow turbulence of water bodies around the cages (Hartstein, et al., 2004) found that points which have highest average flow regime, got the lowest organic content percentage and organic matter content at farming area was always higher than the surrounding areas Severely reduced the flow in the central area of ropes increased deposition speed

- Eutrophication caused by redundant feed and feaces

Aquaculture caused eutrophication due to receiving waters is similar to that derivied from other points of polluted sources (Persson, 1991) However, most cultured areas are limited dilution, then, nutrients are generally dissolved in the water and/or built

up in sediment where organic matter accumualted under the cages (Kaiser, et al., 2011)

In common feed regime, nutrients comprises 1.4 – 13.6% N and 0.3 – 5.9% P (Cho, et al., 1998) Organic enrichment may lead to release of nutrients (N, P) from settled organic wastes in sediment and therefore contributing eutrophication by shifting oligotrophic or mesotrophic water bodies to eutrophic state (Environment-Canada, 2009) These environmental changes in water column related to outbreaks of toxic algae and aquatic mass mortality (Smayda, 1990)

- Destruction of the natural ecological environment

In the early years of the shrimp industry, the areas occupied by mangrove forests (mangroves) which are considered less economic value, are ideal for the development of shrimp farms They are natural habitats for many shrimp species and the best location for shrimp farms (Fegan, 1996) The digging – pond preparation for breeding purposes has destroyed 20% of the mangrove forests in Ecuador (Phillips, et al., 2003)

Today most countries culturing shrimp have recognized the importance of mangroves They are natural habitats and nurturing, foraging ecology of birds and animals They also prevent coastal erosion under the impact of storms and waves The balance between the profitability of shrimp farming and ecological benefits while protecting mangroves in some countries have taken place to protect In Thailand, only 12% of mangrove forests is outside protected areas are allowed shrimp farming and 61%

of the areas are maintained its natural state (Pongthanapanich, 1996)

Seed collection process also affect the ecological environment by capturing the natural seed from the wild These actions reduce feed intake of birds and increase the physical impact on the seabed by fishing gear, trampling all over the beach In addition, the introduction of alien species when selecting brood stock can lead to habitat disturbance when adding gravel, stone and other materials to create a solid foundation for the bivalve development Remove birds, fish, crabs from feeding grounds by using protective nets In harvest process can cause bottom disturbance by using mechanical harvesting equipment and mass mortality of by-catch creatures in the culture areas

1.2 OVERVIEW OF DOMESTIC RESEARCH SITUATION

1.2.1 Aquaculture activities

1.2.1.1 Aquaculture operations in South Central coastal provinces

The South Central coastal provinces including: Da Nang, Quang Nam, Quang Ngai, Binh Dinh, Phu Yen, Khanh Hoa, Ninh Thuan and Binh Thuan

The largest resource of these regions is marine economy in which fishery resources (accounting for nearly 20% of the Vietnam’s catches) and aquaculture such as shrimp, lobster, grouper, pearl etc It is advantageous because of the appearance of many shrimp and fishing grounds In recent years, marine fish yield in the South Central coastal regions accounted for more than 29% of the Vietnam’s catches Particularly at the poles of South Central, there are huge fishing grounds, many bays, lagoons etc which are favorable for aquaculture in Hoang Sa (Danang) and Truong Sa (Khanh Hoa) In Phu Yen and Khanh Hoa, farming of lobster, black tiger shrimp are thriving

According to the Department of Aquaculture (2012), lobster in Vietnam distributed from Quang Binh to Binh Thuan, but is most concentrated in Phu Yen and Khanh Hoa province Lobster cage farming has really developed since 2000 Until now, the number

of estimated cages are more than 53,000 cages, over 23,627 cages in Phu Yen, Khanh Hoa Province: 28 455 cages with approximately 8,000 - 10,000 households, production reached 1,600 tons / year, bringing the turnover nearly 4,000 billion/year

Table 1.2: Current status of fisheries and aquaculture in the South Central Province from

2009 to 2013

Water surface area of aquaculture

(thousand ha) 24.7 25.8 26.3 29.4 26.4 Offshore fishing vessels (unit) 11838 12027 11617 12209 12586

Fishery production (ton) 720303 748123 795201 846776 884352

Exploitation of fishery production

(ton) 644709 684974 713945 764139 801084

Exploitation of marine fish

production (ton) 485.7 516.9 539.6 578.8 600.3

Aquaculture production (ton) 75594 77850 81254 82638 83261

Cultured fish production (ton) 16215 18104 19772 20194 21099

Farmed shrimp production (ton) 52095 51964 54985 53954 52967

Source: the General Statistics Office 2014

As seen from Table 1.2, in 2013, the water surface area of aquaculture of this area is 26.4 thousand hectares, increased of 2.27% compared to 2010, but decreased 10.2% compared

to 2012 because government launched a policy to protect the ocean and tourism (Decision

No 2293 / QD-UBND) However the total aquaculture production of the whole region still reached 83 261 tones, slightly decreased compared to 2012 Among them, farmed shrimp production accounted for 63.6%, cultured fish production accounted for 25.3% of total production

1.2.1.2 Aquaculture activities in Khanh Hoa province

Aquaculture and fishing are mainly taken place in Nha Trang Bay, Khanh Hoa Province Nha Trang Bay focused on exploiting two main resources are fishing, aquaculture and tourism Fishing operations tend to develop in order to cater for the processing industry and tourism Presently, the aquaculture areas include: Tri Nguyen, Hon Mot, Bich Dam and Dam Bay, Hon Mieu with a total area of about 263 ha Fish stock in the Bay accounts for approximately 30% of the total reserves of the province,

including pelagic fish stock about 70% (The General Statistics Office 2014)

Table 1.3: Current status of fisheries and aquaculture in Khanh Hoa Province from 2009

to 2014

Year 2009 2010 2011 2012 2013 2014 Preliminary

2015 Water surface area of

Fisheries production

(tons) 74356 75242 75178 80160 82300 85000 88000 Captured marine fish

production (ton) 1535 2787 3501 3468 3527 -

Farmed shrimp

production (ton) 6949 7188 7857 7620 7047 6530

Source: the General Statistics Office 2014

* Captured fisheries: fishing yield in 2014 reached 85 thousand tons, equal to 95.18% of the plan, an increase of 3.16% in comparison with 2013, of which more than 76 thousand tons of fish, increased of 3.86%, more than 1.3 thousand tons of shrimp, increased 13.17% and other seafood

* Aquaculture activities: Aquaculture in Nha Trang Bay is mainly semi-intensive (intensive form of farming accounts for 20%, 80% semi-intensive) Aquaculture production in 2014 reached 14 thousand tons, an increase of 1.81% compared to 2013, of which over 6.1 thousand tons of whiteleg shrimp, an increase of 6.57%; 0.43 thousand tons of shrimp, an decrease of 25.42% compared to 2013,due to many black tiger shrimp farming households have switched to culture white shrimp (because of their short culture period, high yield, less disease, high efficient economy) The shrimp and fish production reached their peak in 2011 From 2012 to 2015, the production was lower due to in some aquaculture areas were in cleared areas, must be relocated and some areas turn to other aquatic species such as snail, sea bass, grouper aquaculture area in 2014 reached 5829.4 hectares, an increase of 1.5% in comparison with 2013 due to favorable weather for farming all kinds of seafood, including black tiger shrimp farming area was 330 ha decreased 36.3%, an area of white shrimp culture 2992.7 hectares, up 8.9%

* The number of vessels in province around 3140, of which 2000 vessels operates in Nha Trang Bay area However, the vessels whose capacity of under 20 CV account for about 40% (1.246 vessels), about 780 vessels of high capacity (> 90 CV) Therefore, the

overexploitation of coastal resources is inevitable Besides, destructive fishing and collective methods such as bottom trawling, dynamiting, electrical impulses etc make the resources in the Bay are seriously threatened

* The main cage culture types: are “lobster (Panulirus ornatus, P hormarus, P timpsoni, and P longipes) Groupers (Epinephelus bleekeri, E akaara, sexfasciatus, E malabaricus, E coioides, E merra and Cephalopholis miniata), Seabass Lates calcarifer, Yellowtail Seriola dumerilli, Sea bream Parargyrops edita, Snapper Lutjanus spp., Sea- horse Hippocampus, Pearl oyster (Pinctada maxima, and P martensii), and ornamental

fishes were also cultured in cages” (Tuan, 2003)

Table 1.4 Summary of the commonly cultured species in Khanh Hoa Province

Scientific name

& synonyms

Common names Distribution Habitat Seed supply Culture form

E malabaricus

Malabar grouper, Estuarine grouper

Ton Kin gulf, Southern Central Sea

Marine and brackishwater

Coral, rocky reefs, sandy and muddy bottoms, tidepools, estuaries, mangrove; juveniles occur in shallow coastal waters

Ton Kin gulf, Southern Central Sea

Marine, demersal; common in

grouper

Ton Kin gulf, Southern Central Sea

Shallow-water coral reefs in

grouper

Ton Kin gulf,

E.bleekeri

Duskytail grouper, Yellow spotted grouper

Ton Kin gulf,

Cephalopholis

Well-developed exposed coral

Lates calcarifer Seabass,

* Lobster cage aquaculture: There are 6 lobster cage-farming areas in Nha Trang Bay: Vung Ngan, Dam Bay, Tri Nguyen, Bich Dam and Vung Me as shown in figure 1.1

No of cages (cages)

Culture area (ha)

No of

HH (HHs)

No of cages (cages)

Culture area (ha)

No of

HH (HHs)

No of cages (cages)

Culture area (ha) Vung Ngan 50 1191 2.050 82 2622 - 79 2576 3.7600

the period of 6-year, Vung Ngan has the largest farming area, number of households and cages compared to the rest areas while Bich Dam has the lowest number of cages and cultured areas

The economic development policy of the provincial People's Committee towards Nha Trang Bay was exculsive development of marine eco-tourism and entertainment Therefore, all forms of fishing and aquaculture are strictly prohibited ( http://baokhanhhoa.com.vn/kinh-te/201106/khai-thac-nuoi-trong-trong-vinh-nha-trang-can-huong-toi-muc-dich-ben-vung-2078691/) The plan is that by 2015, sea-cage aquaculture in Nha Trang Bay will be reduced to 62.5 hectares of water surface (current state of 78.3 hectares); the total cages are reduced to 3518 cages/232 rafts with 221 - 232 households (http://www.khafa.org.vn/?cmd=newspub&cmdid=newspub-detail&idnew=835.) However, until the end of 2015, aquaculture activities in Nha Trang Bay was still chaos, concentrating mainly in Hon Mieu, Vung Ngan, Bich Dam, Dam Bay and Hon Mot (Vinh Nguyen Ward); accounting for 85% of water surface area with 3645 cages (Aquaculture Department - Khanh Hoa Aquaculture Department, 2016) mainly lobster and marine fish

1.2.2 The impacts of aquaculture activities to environment and ecosystems

In Nha Trang Bay, due to lack of planning, aquaculture developed at coastal zone quite massive and spontaneous, fragmented and not planned, increasing area expansion, scale and farming methods are also diverse, mostly extensive

The uncontrolled aquaculture without planning and regulation has had a negative impact on the sorrounded water bodies and benthic fauna and flora (An, et al., 2005) The disputes of farming grounds always caused chaos which made the environmental situation worsening (Trang, et al., 2009) Organic wastes from aquaculture including leftover feed, settling, wastes from living activities, chemicals… have caused numerous environmental problems (Du, et al., 2006) The coral communities in the bay have significantly deteriorated compared to the results of the first hydro-biological surveys in the early 1980s By the beginning of the 21st century, the average coral cover in the bay was less than 30% (Tkachenko, 2015)

- Redundant feed direct discharged into the environment

The floating cages are only visible buoys above the surface water, anchor ropes and the zone beneath the cages will be affected by the falling uneaten feed and fish faeces Some studies show that only 17% of the dry weight of feed supply is converted to biomass, the rest is discharged into the environment as faeces and excess decaying organic matter (Du, et al., 2013) It leads to heavily contaminated water bodies, eutrophication and increasing aquatic diseases to livestock (due to lack of conditioning and adjustment factors), coral reefs and benthic fauna

- Organic wastes deposited in sediment

Organic wastes deposited in sediment lead to reduced natural productivity and biodiversity loss Composition of wastes in sediment are mainly organic substances such

as proteins, lipids, fatty acids with the general formula CH3(CH2)nCOOH, photpholipids, sterols - vitamin D3, hormones, carbohydrates, minerals and vitamins, molting shrimp shell etc These kind of wastes are always submerged, anaerobic which makes anaerobic microorganisms thrive These decomposition sediment compounds formed hydrogen sulfide (H2S), ammonia (NH3), methane (CH4) (Tuan, 2005) The sedimentation on the bottom which is anaerobic reflected in the low ratio of (Fe2O3/FeO), the low amount of sodium nitrate In contrast, the amount of toxic substances such as H2S, NH3 are high

H2S gas is maximum between 0 - 20cm in the sediment The above substances show strong reducibility in sediments, causing a lack of oxygen, inconsistent with bottom living animals (Binh, 2008)

- Destruction of the natural ecological environment

Almost farming areas have been a particular ecosystem for many aquatic creatures occupied However, the farming procedures disturbed its residents because farmers did not understand the process of environmental changes in the farming sector, lack of understanding of ecological characteristics of cultured species, lack of capital Many farmers have failed on cultured species or these areas could only be used in a short time After several years, degradation happens and is abandoned Farmers come to the new

region to culture, destroying the new region caused huge waste of natural resources (Hong, 1995)

On the other hand, biological products, chemicals used in aquaculture that may impact on the environment, these products include: antibiotics, toxic chemicals and nutrition group The degree of use of chemicals in intensive farming was highest There are many drugs on the hazardous list but still sold on the market Most drug dealers are not eligible in business Many products are not properly labeled (Tai, 2003) Trung, et al.,

2011, claimed that using the antibiotics to treatment has been effective in reducing the mortalities in the short times; but they are not effect on increasing output of production In addition, discharging waste water (may contain antibiotics and chemical pollutants) from the hatchery to surrounding areas can cause the risk of pollution

1.3 THE IMPACTS OF EUTROPHICATION AND SEDIMENTATION ON CORAL REEF

One of the biggest threats to coral reef health was direct anthropogenic effects such

as effects of eutrophication and sediment from intensive aquaculture activities Elevated nutrient concentrations levels beyond certain thresholds can have fatal direct effects on the physiology of the coral holobiont, especially under heat and light stress, such as reduced reproductive success, calcification rates, skeletal density or linear extension Indirect negative effects of elevated nutrient levels can contribute to increase the productivity of coral reef macroalgae The algal cover can lead to competitive inhibition

of coral recruitment by shading/overtopping, reducing water exchange, and causing mechanical abrasion or chemical disturbance Algal blooms and resulted in thick mats of filamentous algae covering of the reef and in extensive coral death (Cecilia, et al., 2014) Nowadays, the problem is much larger in scale (Wilkinson, 1999) 50-70% of coral reefs are directly affected by anthropogenic global climate change (Hoegh-Guldberg, 1999) The human impact on climate during this era greatly exceeds that due to known changes

in natural processes (IPCC, 2007) The coral communities in Nha Trang bay have significantly deteriorated compared to the results of the first hydro-biological surveys in the early 1980s By the beginning of the 21st century, the average coral cover in the bay was less than 30% (Tkachenko, 2015) Sediment originating from fish farms has become

one of the most important disturbance factors on the degradation of inshore coral reefs in the world (Hoegh-Guldberg, et al., 2007) (Rogers, 1990) (Smith, et al., 2010) Deposited sludge in aquaculture that contains faeces of fish and shellfish species, decomposing feed, residues of materials used in aquaculture such as: Chemicals, Lime and Diatomite minerals, Dolomite, sulfur, toxic substances in alkaline soil Fe2+, Fe3+, Al3+, SO42-, H2S, NH3 etc are the products of the anaerobic decomposition process Especially, with high-tech farming models, high stocking densities such as intensive culture and industrial farming, the higher the waste volume and the more polluting the environment For shrimp farming in the southern part of Vietnam, the sediment content in seawater is very high, 200-888mg/l, this amount of sediment is deposited in the shrimp pond creating a very thick mud layer Residues of persistent organic matter accumulate in sediment Contamination of persistent organic matter has long lasting effects, as organisms living in the environment will gradually adapt and have the ability to accumulate in human body More seriously, this accumulation will increase steadily along the food chain in the ecosystem and lead to long-term effects (especially harmful organic substances such as pesticides and aromatic polycyclic compounds) (Du, et al., 2013)

Increased suspended sediment concentration in the water column would lead to an increase in seawater turbidity, reduce light availability for zooxanthellae (Fabricus, 2005) (Fabricus, 2011), may result in smothering and bacterial infection of coral tissues and lead eventually its death (Hodgson, 1990) (Staffordsmith, 1993) and reduced coral recruitment, declining biodiversity due to the loss of sensitive taxa (Fabricus, 2005) (Fabricus, 2011) (Van-Woesik, et al., 1999) (Lia, et al., 2013) The large volume of waste accumulated in the pond increases the oxygen demand in the sediment, causing oxygen depletion in the pond bottom, creating anaerobic conditions leading to the production of

undesirable gases such as hydrogen sulfide (According to Aquaculture Times - March 16, 2017) Hydrogen sulfide in sediment can diffuse into the upper surface water, it can also

be mixed into the water column by biological activity and sediment disturbance for pulling nets and strong water currents due to wind or mechanical ventilation If the speed

of hydrogen sulfide diffuses into the water beyond its oxidation rate, it will be detected concentration of this potential toxin in the water column - especially in the few

centimeters above the interface between sediment and water LC50 values of 96 hours (killing 50% of the test animals in 96 hours) of hydrogen sulfide for freshwater fish species ranged from 20-50 μg / L, the concentrations causing stress and make the fish

susceptible to infection are much lower (According to the Global Aquaculture Advocate - March 16, 2017)

1.4 CLIMATE CHANGE FROM THE PERSPECTIVE OF STUDYING THE

ANTHROPOGENIC IMPACTS BY AQUACULTURE

Climate change is intensifying the symptoms of eutrophication and sediment on coral reefs Blue-green algae, which cause noxious blooms, are favored high water temperature Warmer water will have higher densities of fish species that eat zooplankton, the microscopic animals that normally feed on and control algae However, eutrophication can also conversely promote climate change (Moss, et al., 2011) Eutrophication may lead

to lower proportionate dependence on imported organic matter and greater autotrophic fixation of carbon dioxide; nonetheless, it also leads to increased absolute production and respiration, greater release of methane from deoxygenated waters and sediments (Bastviken, et al., 2008) (Bastviken, et al., 2011), and more nitrous oxide from denitrification (Huttunen, et al., 2003) Both the latter gases are more effective greenhouse gases than carbon dioxide (Moss, et al., 2011)

Various global climate change scenarios will likely manifest in many different effects on various components of ecosystems These outcomes may be difficult to detect because there are effects resulting from other human-caused changes but they are currently masked by the inherent “background” variability of natural systems, (Sanderson

et al., 2002; Halpern et al., 2008) As in the sense of multiple human-induced stressors,

we are unable to differentiate completely the global climate change aspect and the anthropogenic activities aspect of global change on eutrophication There is considerable overlap in the pressures and consequences (Rabalais, et al., 2009)

In coastal areas, the current impact of climate change on coral reefs is not clear (the impacts only associated with abnormal rainfall, causing floods and high suspended solids in the coastal zone) One of the biggest threats to coral reef health was direct anthropogenic effects such as effects of eutrophication and sediment from intensive

aquaculture activities (Cecilia, et al., 2014) Growth reduction of coral species occurs due

to smothering, reduced light levels and reduced zooxanthellae photosynthesis caused by eutrophication and sediment (Tomascik, et al., 1987) Nowadays, the problem is much larger in scale (Wilkinson, 1999) 50-70% of coral reefs are directly affected by anthropogenic global climate change (Hoegh-Guldberg, 1999) The human impact on climate during this era greatly exceeds that due to known changes in natural processes (IPCC, 2007)

Anthropologists at National Center for Atmospheric Research (NCAR), along with members of the American Anthropological Association (AAA) Task Force on Global Climate Change stated that it is essential for understanding climate change from the perspective of studying the anthropogenic impacts “Climate change is not a natural problem, it is a human problem.” However, attention to the effects of anthropogenic

impacts is often left out of the climate change discussion anthropology-of-climate-change] Clearly this is a new perspective for coastal

[https://ncar.ucar.edu/press/the-management and reef survival under the anthropogenic impacts on climate change

CHAPTER 2 MATERIALS AND METHODOLOGY

2.1 DATA SOURCE USED

The results of DIN - Dissolved inorganic nitrogen (NH4- N, NO2-N, NO3-N) and DIP - Dissolved inorganic phosphorus (PO4-P), Chlorophyll a were supported from the

VAST05.03/15-16 project which carried out from 2015 – 2016 in Nha Trang Bay All data of sample analysis from coral cross-transplanted in this study was supported from the VAST05.03/15-16 project leader

2.2 SAMPLING STRATEGIES

2.2.1 Study sites and sampling design

The cage-farming area in study site is located southwest of Tre Island (12o10,663’

N, 109o16,535’ E), the biggest one, is located on Southeast of Nha Trang Bay and considered a barrier blocking East waves Thus it can avoid against strong wind and wave actions Water depth along the coast is from 0 to 50m and at farming-cage area, water depth varies from 12 to 20 meters Average wind speed is 2,1m/s and 9,1m/s is the highest value captured in convention condition (Vi, et al., 2006) The depth of cage-farming area is about 10 to 20m The farms use the cages of 16-20 m2 (surface area) consist of cage frame, cage net, floating buoyant and anchor system The cages are often assembled into “rafts” of four or more cages The main cage-farming species are lobster, grouper, red snappers, rabbit-fish etc Lobster and fish are fed by trash fish, crab, mollusc etc twice a day in the morning and in the afternoon with 8kg of feed each cage in August, and decreasing in winter and summer

The study was carried out in May, 2015 and April, 2016 with seven sampling sites were established based on the distance from cage farming area, surrounding and outwards (less affected area): near-field farming cage (NT1 - farming area, NT2 - was set at the center of farming area, NT3 - nearby Mot island which located coral reef areas), mid-

field cage farming (within 1.2km from the cages) (NT4, NT6), far-field of cage farming area about 3km from the cages (NT5, NT7) (Fig.2.1)