Study of some species of mollusks living clung, perforated on the tree mangrove and management capabilities in reducing their harm

In Vietnam, mollusks also been interested in research and have remarkable results in the fields of investigation classification, species composition; biology, ecology; Biodiversity resea

MINISTRY OF EDUCATION MINISTRY OF AGRICULTURE AND AND TRAINING RURAL DEVELOPMENT

VIETNAM ACADEMY OF AGRICULTURAL SCIENCES



HOANG THI THUY DUONG

Study of some species of mollusks

living clung, perforated on the tree mangrove

and management capabilities

in reducing their harm

Specialization: Plant Protection

Code: 62.62.01.12

SUMMARY OF Ph.D THESIS

HA NOI - 2016

The research work was conducted at:

VIETNAM ACADEMY OF AGRICULTURAL SCIENCES

Supervisiors:

1 Prof.Dr Nguyen Van Tuat – Vietnam Academy of Agriculture Sciences

2 Assoc.Prof.Dr Nguyen Dang Hoi – Vietnam- Russian Tropical Center

This thesis an be referred to at:

- Vietnam National Library

- The Library of Vietnam Academy of Agricultural Sciences

INTRODUCTION

1 The urgency of research

The great role of mangrove forestfor nature and man been known as prevent soil erosion, limit the impact of natural disasters, where the livelihood of the people, the breeding ground and the habitat of many marine species There are many reasons degrade mangrovesin the world and our country, including the cause of global climate change, human abilities deforestation, pollution Very early

on, the Party and state have plans to develop mangrove area nationwide, reforestation work is done in the coastal localities Some difficultiesinplanting mangrovesis detected,e.g.: locals not fully understand the role of mangroves, plants are not adapted for growing conditions, environment pollution.Actual investigation lasted several years, focusing on the 2009 - 2015 show that the influence of mollusks for the life of the mangroves is that needs close attention and is one of the elements impair the development of mangroves in both acreage and quality

Mollusks mangroves are diverse and plentiful, they include species of bivalve layer, a shell plate, gastropods, cephalopods, Due

to the wide distribution, has an important role in nature and in human life, were very much scientists worldwide research interest in various aspects such as research on taxonomy, biology, ecology,

In Vietnam, mollusks also been interested in research and have remarkable results in the fields of investigation classification, species composition; biology, ecology; Biodiversity research and resources; food and nutrition; breeding and rearing However, until now, research the harmful mollusks mangroves is very limited and there is no adequate research has been published

Derived from the practical requirements above, the consent of the Ministry of Education and Training, Institute of Agricultural Sciences Vietnam, thesis " Study of some species of mollusks living clung, perforated on the tree mangrove and management capabilities

in reducing their harm " has been made

2 The aim and requirements

2.1 Aim

Identification of species harmful mollusks on mangroves: study the characteristics of biology, ecologyand proposed management measures to reduce the harmful effects of mollusks for mangrove trees

2.2 Requirement

- Investigate to determine the composition mollusk species in some typical areas of mangroves in Vietnam

- Identify mollusk species have caused damage to the mangroves

- Study biological characteristics, ecology of some harmful mollusks

- Studyandevaluate the impact of mollusksonmangrove trees

- Proposed management measures to minimize the harmful effects of mollusks on mangroves

3 The scientific and practical significances of subject

3.1 Scientific significance

- Identify the major species in mangrove 3 areas Cat Ba National Park, Con Dao National Park, Biosphere Reserve of Can Gio

- Provide data on some biological characteristics, ecology of mollusks

in the mangrove sand their harmful ways

3.2 Practical significance

- The results of the study help to build integrated management measures for species at risk of harm to the protection and development

of mangroves efficient and sustainable

- To preserve and exploit the beneficial mollusks serve economic development of mangroves, risk prevention, damage in the development of mangroves, especially in new growing areas

4 Objects and scope of the research

4.1 Objects

- Mollusks (Mollusca), with primitive mouth (Protostomia), Delimitating multicellular animals (Metazoa) and belong to the invertebrates (Invertebrate)

- The mangrove species of mangroves Cat Ba National Park, Con Dao National Park and Biosphere Reserve of Can Gio

4.2 Scope of the research

+ Scope of the study: The study of species harmful mollusk in mangrove area Cat Ba National Park, Con Dao National Park and Biosphere Reserve of Can Gio; study the characteristics of biology, ecology of mollusks; recommended management measures to minimize harm caused mollusks for mangrove trees

5 New contributions of the thesis

- Develop a list of species of mollusks mangrove area Cat Ba National Park, Con Dao National Park, the Biosphere Reserve of Can Gio

- Detect 4 mollusk species harmful mangrove areas in Cat Ba National Park, Con Dao National Park, the Biosphere Reserve of Can Gio and study the characteristics of biology, ecology live mollusks clinging, harmful to mangroves

- Proposed measures to reduce the harmful effects of mollusks in mangroves and building synthetic process their harm reduction

6 The thesis structure

The thesis has 163 pages, including the opening 5 pages Chapter 1 is introductry and defines scientific basic and documents use in research (28 pages) Chapter 2 illustrates the materials, content and methodology (17 pages); Chapter 3 shows the results of research and discussion (82 pages); Conclusions and recommendations (2 pages) include 22 tables, 42 figure Reference Documents including 110 items, which 64 Vietnamese documents, 43 England documents and 3 Russian documents

CHAPTER I: BASIS OF SCIENCE AND OVERVIEW OF

DOCUMENT 1.1 The scientific basis of the research

The harmful mollusks to mangrove trees had been dentified in the field and researchers mention in their study as Phan Nguyen Hong(2004), Nguyen Quang Hung(2008) However, until now, there are no studies completed on the composition of harmful animals

The general situation of our country's mangrove forests and the world are in decline, while natural disasters, environmental pollution, climate change and increasingly complex threats to human safety Consequently, the plantation and protection of mangroves are a matter

of urgency However, in fact, mangrove planting not achieve good results for many reasons, but one of the most important cause is the destruction and killing trees by live mollusks and perforated on the tree caused

According to Phan Nguyen Hong (1999), along with the investigation, the study from 2005, in which the focus from 2009 to present, up to 30% of young trees die due to causes mollusks

Determining the composition of species harmful mollusks and their characteristics are the basis of the proposed mitigation measures, improve the efficiency of crops, expanding the area of mangroves,

Determining the composition of species harmful mollusks and their characteristics are the basis of the proposed mitigation measures, improve the efficiency of crops, expanding the area of mangroves, meet forestationtargets in the coastal localities

1.2 The recently status of mangrove forests in the world and Vietnam

1.2.1 The recently status of the world's mangroves

The world has about 18 million hectares of mangrove forests, the Southeast Asian countries accounted for 35% of the area, which, in

the Indian Ocean are the most diverse mangrove forest with 50 species (Spalding, 2010) Mangroves have been faced with many challenges such as mangrove forests in the world continuously declining

1.2.2 The recently status of mangroves in Vietnam

In the report of biodiversity in Vietnam 5th by the Ministry of Natural Resources and Environment shall, (2014), has statistics: in

2012, 56% of the total areas of mangrove forests in Vietnam are considered "plantation"with the variety of species is very low The natural mangrove forests have almost completely disappeared Mangrove forest degradation is evident through the rapid decline in both area and quality of forests In 1943, there are over 408 500 hectares of mangroves, in 1990, the area of mangroves to about 255,000 hectares, 209,741 hectares reduced to in 2006, and 140,000

ha in 2010, only 131, 520 hecta of forest rest by the end of 2012

1.3 Research situation mollusks

1.3.1 Research situation mollusksworldwide

1.3.1.1 Classify

Mollusksareinvertebrate - mollusks, with features such as body puree, can have limestone crust to protect and support, depending on the environment that the crust and body composition subject to change

Research classify mollusks were conducted very early From ancient Greece (322-384 years BC), the philosopher Aristode has many studies on mollusks classification.He was the first founder of the discipline of mollusks and given classification method, he divided them into two big groups are groups with no crust and crust groups However, his method of classification is mainly based on external morphological characteristics of them By the mid 18th century, Linne and his colleagues have inherited, developed a method of Aristode classification and construction of "Systema Nature, 1758" The second half of the 19th century to the early 20th century, scientists like Deshayer (1853), Tryon (1884) studied and classified many species of mollusks distributed in many seas of the world, especially in regions Indian Ocean and the Pacific To 1939, Shintaro described, identifiedis 359 species of mollusks and distribution characteristics outlined in the Sea of Japan, Pacific In Southeast Asia, Zhang Billion (1960) studied and described the morphological characteristics, structure, distribution of more than 200 species of mollusks in the East Sea, of which many species are discovered in Vietnam

1.3.1.2 Biology, ecology

Due to the wide distribution in most of the world's seas and importance in the fields of economic, biological, ecological and

environmental protection, should mollusks were so many scientists on the world of research interest, typically such studies Barnes & Hughes (1999) on ecological characteristics of the class Bivalve In his research, Barnes & Hughes has described mollusk has 3 parts: head, body and legs, the body of most species have bilateral symmetry These characteristics continue to be studied and used in the descriptionof mollusksinthe recent Brand's research (1972) on the

mechanism of blood circulation Anodonta anatina species showed an

open circulatory system of species including the atrium and ventricle, circulation cycle: heart - gaping slit system - the kidneys –gills - heart; According Coe (1943), mollusk is gender division as: male and female clear or bisexual, male and female in one individua Between these two categories, there are intermediate forms The vast majority of primitive mollusks are clear gender division The distinction maybe based on the male genitalia or copulatory organs, shapes and different sizes of males and females; Research of Comfort (1957) about the life cycle and reproductive characteristics, the growth of many species of mollusks, reproductive method of mollusks are plentiful There are self-fertilized species, there are species which have both male and female However, generally there is coordination between the male and female elements The phenomenon of mating between the male element can be fertilized in or external fertilization

1.3.1.3 Research on the harm of mollusks and control measures harmful mollusks

Studies of harm and prevent harmful mollusks almost exclusively focused on the yellow snail species live on land and harm agricultural crops There are also some studies on mollusks published mentioned the pests, but these studies have not addressed specifically about harmful influence of mollusks On the other hand, subject to harmful mollusks are not host plants, such astypical: Studies of harm and prevent harmful mollusks almost exclusively focused on the yellow snail species live on land and harm agricultural crops Also, there are some studies on mollusks published mentioned the pests, but these studies have not addressed specifically about harmful influence

of mollusks On the other hand, subject to harmful mollusks are not host plants, such as typical: Hunt &Scheibling studied (1998) on ecological distribute in space and time of the green mussel on the stone reefs in coastal zones The researchs by Hunt & Schilling (1998) about the distribution of spatial ecology and time of green mussel on the stone reef in the coastal zones published Researchs had shown the distribution of green mussel in the stone reefs zones, although not rated harm that study the distribution of green mussel but this study has shown the influence of this mollusks species for stone reef and stone works Quayle's study (1988) on the Pacific oyster in waters

Columbia This oyster species are bred for commercial, however, the Ministry of Natural Resources and Environment said the Pacific oyster species that affect survival of many species of zooplankton and larger animals

It is easy to see that the research works on harmful mollusks are rarely The mollusks are studied and perceived to be harmful primarily for the hosts as the reef, ships, boats and other construction work Studies onthe effects of harmful mollusks and control measures harmful mollusks should be supplemented and further strong interest 1.3.2 The situation of domestic research

1.3.2.1 Investigation of species composition

Vietnam is a country located in the tropics, the East and South are landlocked, many bays, there are hundreds estuary empties into the sea, creating diverse mollusk fauna is rich in species composition , including many species of high economic value, many rare species characteristic for the waters of Vietnam (Nguyen Huu Phung and cs.1996) Since 1905-1906, Dautzenberg and Fisher (1906) was the first to conduct investigations, fundamental research on species composition, structure, distribution of mollusks Vietnam Until 1906, the two authors have collected 97 species in the coastal areas of Thanh Hoa The general survey of Vietnam-China cooperation in the North Bay (from year 1959 to 1960), has identified 336 species of mollusks, for the years 1974 to 1980, the authors conducted a test, determined all kinds of mollusks form The results have identified 369 species belonging to 174 genera and 87 families in the same 5 layers In particular, the class of bivalve (Bivalvia) has 160 species, 74 varieties

of 36 of them (Nguyen XuanDuc, 2003) In 1978, Nguyen Van Chung

et al also announced 190 species of mollusks investigation BinhCang Bay - NhaTrang, where animals classes Bivalvia includes 70 species,

common species is common Mitram elegera, Vexillum cruentata,

cerithium kochi, Turitella terebra, Meretrix tribulus (Nguyen Van

Chung et al, 1997) Nguyen Chinh (1996) summarized the research and introduction of 88 species of mollusks have economic value in Vietnam Sea, bivalve class includes 24 species, each specie is described on characterized morphology, geographical distribution and economic value, this is one of the important documents for reference and distinguish the types of fauna quickly Bivalvia in Vietnam

1.3.2.2 Biology, ecology

Nguyen Huu Phung (1999) investigated the biological

characteristics and resources Blood cockle (Anadara granosa) in the

coastal region of Vietnam has described, in the natural, blood cockle distribution mainly in the small and medium bay tidal Besides, Nguyen Huu Phung et al (2001) also studied and described some of

the biological characteristics of species of brown shell (Modiolus

philippinarum Hanley, 1843) in the waters of NinhThuan By 2003,

this author continues to research and describe some of the biological

characteristics of species of brown shell (Modiolus philippinarum Hanley, 1943) in the waters of BinhThuan Nguyen Thi Xuan Thu

(1998), have studied in some detail and full of reproductive characteristics, growth and production techniques of species Scallops

(Chlamys nobilis Reeve, 1952) have described, Scallops large shells,

nearly round, length and height are equal, diverse in color casing, the growth plates closely together

1.3.2.3 Research on the damage and control measures

From the old days till now, the most mollusks are studied with the purpose of assessing the value of diversity and resources, only a handful of which are soft-bodied research and assess damage on some crops shallow planting as slugs, snails and yellow snail

Năm 1967 - 1969, Nguyen Xuan Duc et al thematic survey they Ha wood (Teredinidae) in coastal waters from Mong Cai (QuangNinh) to Door Day (Ninh Binh) obtained multiple animal samples Bialvia Result analysis has identified 22 specimens of their species Teredinidae (including 10 species sp) Existing specimens stored at the Institute of Marine Environment and Natural Resources However, this study limited at the level of investigation of their species composition (Nguyen XuanDuc, 2003)

In our country, since the 1960s the harmful mollusks began to be interested in, research Derived from the ships, rafts, wooden materials

at sea was the attack of a damaged mollusks The researchers sought

to understand, classify and identify some of their species Teredinidae Then, the method toprotecg vessels and rafts and marine equipment made of wood materials have been proposed in two directions is the use of high temperature fire and used chemicals destroy

Chapter II: RESEARCH CONTENT, MATERIALS AND

METHODOLOGY 2.1 Materials research

Use of equipment, chemicals and laboratory instruments, laboratory chemicals field

2.2 Research content

1 Study on characteristics of mangrove area of Cat Ba, Con Dao, Gio

2 Study on mollusk species studied area

3 Identify pests and characteristics of the pests

4 Study the effect of the pests to the mangroves

5 Recommend measures to reduce the harmful effects of the mollusks to mangroves

2.3 Research methods

2.3.1 Study methodology natural features mangrove area Cat Ba National Park, Con Dao National Park and Biosphere Reserve of Can Gio

• Investigation of mangrove plant research areas: according to section, online surveys ensure passing define habitat of mangrove trees Classification is based on the classification system of Pham Hoang Ho combined evaluation and classification of experts

• Distribution of the intertidal zone, based on the principle of division of Stephenson tidal area (1949)

• Measure the water environment indicators: using portable measuring equipment Hanna Establish measuring stations in the study area and measured seasonally Classification of countries according to the scale of distribution of Zernop (1934)

2.3.2 Research methods for components of mollusk species Survey methods, data collection in the field, analyze, evaluate biodiversity and resources mollusks shall comply with the instructions

in the documentation of the WWF (2003) Classification Model: Using the latest classification system now Author Beesley et al (1998) 2.3.3 Method of determining the pests and their characteristics: Identifying pests based on their behavior

2.3.4 Research Methodology effects of the pests to mangroves Count mortality (CC) and mollusks live clinging plants (TMSB) using the formula:

CC or plant number TMSB

Rate% CC or TMSB = - x 100

The total number of trees to be monitored

2.3.5 Construction propose measures to reduce the harmful effects of mollusks to mangroves: Effectiveness of plant protection products on mollusks formula Henderson – Tilton

2.3.6 Data processing methodology: To Use Excel and Primer 6.0 software to process and analyze the data

2.4 Research location and time:

2.4.1 Research location:

- Laboratory of Tropical Ecology Institute (Vietnam-Russia Tropical Centre); Plant Protection Institute, Fisheries Research Institute,

- Mangrove Area Cat Ba National Park, Con Dao National Park and Biosphere Reserve of Can Gio The following mainly research areas: + Cat Ba National Park (HaiPhong): mainly research area Gia Luan, Ghenh Goi and Phu Long

+ Con Dao National Park (Vung Tau): mainly research area in Dam Tre

+ Can Gio Biosphere Reserve (Ho Chi Minh City):

2.4.3 Research time: From May 01/2009 to 9/2015

CHAPTER III: RESULTS AND DISCUSSION

3.1 Characteristics of mangrove research area

Investigation components mangrove species of mangrove forests

of Cat Ba, Con Dao, Gio shows, the mangrove species found mainly

in these areas is Su (Aegiceras corniculatum), Vet (Bruguiera

gymnorrhiza), Đươc(Rhizophora apiculata), Mam (Avicenia alba)

and some other species such as Cha la (Phoenix paludosa), Coc (Lumnitzera littoralis), Gia(Excoecaria agallocha), In particular,

Su, Vet are two mangrove species frequently encountered in all 3 areas of study; Mangrove trees are regularly caught in the mangroves and Gio Con Dao; Mam is frequently encountered tree in mangrove forests of Cat Ba

3.2 Diversity and distribution of species of mollusks research area

Results of species of mollusks collected through survey research

in three areas: mangroves Cat Ba Island and Con Gio mangrove forest

52 species, belonging to 20 families, focusing on Gastropoda and Bivalve In particular, the Can Gio mangrove forest with high levels

of species diversity, the number of species surveyed 40 species (= 77% of total species recorded) of 18 families (4 species of Gastropoda, 36 species bivalve class), followed by the Cat Ba with 27 (= 52% of the recorded species) species belonging to 16 species of the family of 4 and 23 Gastropoda class bivalve species The lowest is the region Con Dao with mangrove species number 17 (= 33% of total species recorded)

3.3 Characteristics of harmful mollusks for mangroves

3.3.1 Species composition harmful mollusks

As mentioned in Part components mollusk species in three research areas (mangroves Cat Ba, Con Dao, Gio), in addition to distribution in the intertidal zone, the sand, mud, also recorded get some mollusk species distributed on the leaves, stems and live perforated in the trunk When mollusks clinging on a tree will cause damage to the mangroves.There are two main types of damage include:

+ Type 1: When mollusks clinging on a tree, the tree was sticking section shaggy, stunted This is a symptom caused by mollusks

+ Type 2: When molluskswere perforated in the trunk, the tree section

is perforated, broken items, with the hole through the trunk This is the kind of symptoms caused by mollusks living in the trees

According to preliminary investigations, with 15 random plots (10m x10m) and along the routes observed in every region of mangrove forests, the proportion of cells that live mollusks clinging trees up to 40-50% of plots From the 52 species investigated mangrove area of Cat Ba, Con Dao, Gio identify pests 4 for mangroves Include:

- Live grip on the leaves, stems: 3 species identified as Diep (Anomia

cytaeum), Hau (Saccostrea cucullata) and Queo (Brachyodontes emarginatus).Mollusk species cling on mangroves, individually or

into dense crowds on the trees causing stunted, deformed or dead

trees

- Live perforated in the trunk: Identify species Bankia Sauli (Wright,

1866) in the area of Can Gio mangrove forest This mollusk species gradually carve into the trunk, live in the trunk and destroying trees

In 4 mollusk species in the mangrove harmful,3 species in all

three study areas are: Diep (Anomia cytaeum), Queo (Brachyodontes

emarginatus) and Hau (Saccostrea cucullata); Ha (Bankia saulii) only

found only in the area of Can Gio mangrove forest So, 3 species:

cucullata be brought into the next study

Table 3.9.Species compositionof harmful mollusks to mangroves

Can Giơ

3.3.2 Characteristics of harmful mollusks on mangroves

3.3.2.1 Characteristics of Saccostrea cucullata(Born, 1778)

ClassisBivalvia

OrdoOstreoida

FamiliaOstreidea

Genus Saccostrea

• Morphological characteristics and structure of the body

Crust thick, heavy, abdomen edges curved Crust shape significant changes, usually oval shaped or triangular, height and length of the shell is not stable, opaque white, outside shaggy, rough Oysters have uneven shell 2 piece, a large shell containing introspective piece, small is piece lids Deep concave surface of milky white crust, stain adductor muscle behind his back near the edge of the shell, light brown The two crusts are closed in, opened by two front adductor muscle and the rear muscle

Simple digestive system, intestine before mouth, the two sides have two lobes mouth, long midgut section, are rolled into song in the body, into the hindgut in the back position There siphon drainage and suction Unisexual reproductive system Gonads are in the body, surrounded by intestines Respiratory system included 4 gill plates, two outer plates thinner than mitral in Gill's surface have natatory hair, always active causing the water enters, bring food and dissolved oxygen Structure characteristics of gills, their shaped is plates, including gill filaments arrangement the two parties Water goes into gills, bring food The food selection to follow physical properties These lightweight beads, small, finely taken to the mouth, the grained, heavy falling edge of the mantle and was taken out

• Characteristics of distribution:

Oysters live mainly on the mangrove trees, rocks and other substrates in the intertidal zone

• Nutritional characteristics:

Saccostrea cucullata is powerful filter feeders group, favorite

food is algae and detritus small size Thus, they act as biological filters, water purification

• Growth characteristics:

Individual size Oysters grown at about 9-10cm shell length, 250g weight The growth rate of Oyster crusts vary by region and are affected by environmental conditions Water temperature is the most influential factor Low winter water temperatures influence on the growth of the crust