olamide olabisi final year project

1

CHAPTER ONE

1.0 BACKGROUND INFORMATION

Lagoon is derived from the Italian word laguna, which refers to the waters

around Venice, the Lagoon of Venice. Laguna is attested in English by at

least 1612, and had been Anglicized to "lagune" by 1673. In 1697 William

Dampier referred to Lagune or Lake of Salt water on the coast of

Mexico.[Lagoons are prominent features along the coastal regions of

South-Western Nigeria. Some of these Lagoons are part of West African

lagoon system in origin and location but are in form and features similar to

freshwater lakes (Webb, 1958). The other types of lagoons are essentially

brackish and tidal effects are experienced particularly in the dry season.

However, all the lagoons of south-western Nigeria enter the sea through

the Lagos Harbor (Nwankwo, 1998a). Epe lagoon the only lagoon in south-

western Nigeria sandwiched between two lagoons (Lagos and Lekki

lagoons).

Out of the six lagoons (Mahin, Lekki, Epe, Lagos, Ologe and Yelwa) on

the south-western coast, the Lagos lagoon is the most extensively studied

in relation to the others. This may obviously be attributed to the

metropolitan nature of Lagos and the ease of access.

2

Just like every other environment of deposition, sediments are deposited in

the Lagoon. Microfossil assemblages in lagoon sediments contain many

valuable clues to paleoclimate and paleo-oceanography, Water Quality.

Unfortunately, our understanding of production, dissolution, redisposition,

and other processes of microfossil sedimentation is but rudimentary.

Lacking direct observations, information largely rests on comparisons

between abundance and composition patterns of life-, death, and sediment-

assemblages (Berger 1971).

According to (Sattarova et al, 2015), Diatom assemblages reflect present-

day water masses characterized by high nutrient content, surface water

circulation, and sedimentation conditions for different parts of the study

area. Analysis of this new data also highlights changes in the response of

diatom flora due to abiotic factors.

Several microfossil groups are particularly useful in bio-stratigraphic

correlation, paleo-environmental reconstruction, and paleoceanography

(Braiser 1995).

Thus, Diatoms are used extensively in environmental assessment and

monitoring.

Furthermore, because the silica cell walls do not decompose, diatoms in

marine and lake sediments can be used to interpret conditions in the past.

3

Paleoecology is a field that utilizes both living and subfossil diatom valves

that are preserved in marine and freshwater sediments (Smol et al 2010).

1.1 STATEMENT OF PROBLEM

Epe lagoon lays in-between two lagoons the Lagos and the Lekki lagoons

which are relatively more documented. The paucity of information on the

micro-paleontological characteristics of this sandwiched lagoon prompted

this present work. A survey of the microfossil of the sediment from Epe

lagoon was carried out in the early April 2015.

The micro-paleontological studies of the Epe lagoon have been carried out

very few times in recent survey. The types of microfossils present; their

structures, morphology, shape, age-range is less known. This study will

add to the wealth and body of existing information and present a more input

into further studies. The study of microfossils, particularly in fresh water

lagoon is used to infer the depositional environment of the lagoon, at the

same rate they are also used for paleo-environmental reconstruction. But

due to the low level of micro-paleontological research carried out in the

Epe lagoon, inferring the depositional environment may pose a difficult

task.

To a very large extent, this research work will be able to proffer solutions

the aforementioned challenge.

4

1.2 AIM

The aim of this study is to determine the microfossil composition of the

Epe Lagoon sediments; its morphology and its characteristics. Also, to use

the microfossils present to infer the depositional environment of the

lagoon.

1.3 OBJECTIVES

Objectives of the study include;

-Identification of Microfossils (Diatoms) present in the sediments

-Estimating the percentage composition of each component

-Identifying Microfossils that serve as indicators

1.4 DESCRIPTION OF THE STUDY AREA

1.4.1 Location of Area

Epe lagoon is located in Lagos state, South-west Nigeria; it lays in-between

two lagoons, the Lagos lagoon (Brackish water) to the west and the Lekki

lagoon (Fresh water) to the east, both of which are relatively more

documented (Fig 1).

Epe lagoon is connected to the Atlantic Ocean through the Lagos harbor,

It lies between longitudes (N 06o 33.710 o E 004 o 03 o.710) and latitudes

(N06 o 31.893o E 003 o 31. 912 o). The Epe lagoon has a surface area of 243

km (Kusemiju 1988).

5

The lagoon has an average depth of about 1.8m and a minimum depth of

2.8m. (Edokpayi et al, 2008).

The Epe lagoon supports a major fishery in Lagos state, Nigeria and it is

also used as transportation route for people, goods and timber logs from

Epe to other places in South-Western Nigeria. The lagoon houses the Egbin

thermoelectric power plant which serves as a major source of electric

power generation in Western Nigeria. The lagoon is the major source of

water for the inhabitants of Epe and other villages situated along its bank.

Over the years the population of Epe and other villages along the bank of

the lagoon has increased through expanding commercial activities.

1.4.2 Climate

The wet and dry seasons are observable in the climate of southwestern

Nigeria, which is tropical in nature. The temperature ranges from 21 to 34

0C, while the annual rainfall ranges from 150mm to about 300mm

(Faleyimu et al., 2013). There are two peak periods of annual rainfall,

which are June to July and September to October, with a slight break in

August referred to as “August break” (Onakomaya, 1992; Ikhane et al

2013). The wet season is associated with the southwest monsoon wind

from the Atlantic Ocean, while the dry season is associated with the

northeast trade wind coming from the Sahara desert. Due to its closeness

to metropolitan cities of Lagos state the settlement sites are characterized

6

by floating mate of aquatic vegetation dominated by water hyacinth

(Eichhornia crassipes).

1.4.3 Rainfall

Rainfall season is characterized by two equinoctial maxima in Lagos state

and its environs. Mean monthly rainfall varies between 19mm and 64mm

during the dry season (November to March). During the rainy season

(April-October), mean monthly rainfall ranges between 162mm and

237mm. The first rainfall maxima experienced between May and July is

intense and could be characterized by abnormal rain amounts of between

200 and 264mm daily (Awosika et al., 2011).

1.4.4 Temperature

Air temperature in and around Lagos state vary from high to very high

throughout the year. The maximum temperatures in Lagos range between

32oC and 35oC. These high temperatures are experienced between the

months of January and March (pre-rainy season). Minimum air

temperature in Lagos ranges between 22.5oC and 26.0oC in January, July

and August. However, there are certain periods in January, July and August

when minimum temperatures exceed 25oC. Temperatures in July and

August are unusually low, (between 23oC-25oC).

1.4.5 Vegetation

7

The vegetation around the Epe lagoon (its shores) is characterized by still

rooted trees, the most discernible is the palm trees ranging in heights. There

is also the presence of water hyacinth, Eichhomia crassipes usually are

very many at the edges of the lagoon and also floating like an island on the

surface of the lagoon water. There is also the presence of mangrove trees

e.g. Rhizophora racemosa sp.

Study site: Epe lagoon (2°50′-4°10′N, 5°30′ - 5°40′E)

Fig 1 Epe Lagoon bounded the Lagos and Lekki Lagoon (Clement Aghatise 2011) 1.5 Literature Review

As their name implies, microfossils are very small remains of organisms

that require magnification for study. Collectively, they range in size from

less .001 mm (1 micron), which is invisible to the naked eye, to the 1 mm

size of a coarse sand grain, although some forms grow up to 20 cm. The

latter are still referred to as microfossils because they belong to the same

8

taxonomic group as the minute forms, and they also require microscopic

study for identification. Whereas plants, invertebrates, and vertebrates are

distinct taxonomic groups, the paleontology sub-discipline of

micropaleontology encompasses a heterogeneous array of minute fossils.

They can be plant or animal, unicellular or multicellular, mineralized or

organic, shells or skeletons, seeds or spores, teeth or jaws, or enigmatic

forms of unknown affinity. Because they are so small, thousands of well-

preserved specimens can be retrieved from a small sample of sediment or

sedimentary rock (Bignot, G., 1985).

Micropaleontology can be roughly divided into four areas of study on the

basis of microfossil composition:

a) calcareous, as in coccoliths and foraminifera,

b) phosphatic, as in the study of some vertebrates,

c) siliceous, as in diatoms and radiolarians

d) organic, as in the pollen and spores studied in palynology.

Tests carried out in this project were aimed at determining the microfossil

composition of the Epe Lagoon; its morphology and its characteristics

details, where results will be used to infer the depositional environment for

paleo-environmental reconstruction.

9

A total of 11 sediment samples preserved with formalin were collected

from the lagoon, the various samples composed of microfossils from

various location points of the lagoon notably.

Microfossils of interest in the Epe Lagoon are diatoms, Acid clean

preparation were used to treat the samples to isolate the diatoms present in

the samples.

The most common siliceous microfossils in Quaternary deposits are the

frustules of diatoms whose dimensions are of the order of 10 to 100

micrometers. Diatoms are indeed the dominant component of primary

productivity in most marine and lacustrine environments. Their

concentrations can reach millions of individuals per litre in the water

column, and hundreds of millions of frustules per cubic centimeter in the

sediment.

Diatoms are photosynthesizing algae; they have a siliceous skeleton

(frustule) and are found in almost every aquatic environment including

fresh and marine waters, soils, in fact almost anywhere moist. They are

non-motile, or capable of only limited movement along a substrate by

secretion of mucilaginous material along a slit-like groove or channel

called a raphe (Boardman, R. S 1987), Being autotrophic they are restricted

to the photic zone (water depths down to about 200m depending on clarity),

both benthic and planktic forms exist,

10

According to (Jones, D. J., 1956) many of the commonly studied groups

are unicellular, such as Foraminifera, Calcareous Nanoplankton (e.g.

Coccolithophorids, discoasters), Dinoflagellates, Acritarchs, Diatoms and

Radiolarians. Others are Microinvertebrates (e.g. Ostracodes) or parts of

Macroinvertebrates (e.g. Conodonts), reproductive bodies of plants (e.g.

spores and pollen), or of uncertain affinity (e.g. chitinozoans)

The studies have been primarily on Diatoms, which are unicellular,

although they can form colonies in the shape of filaments or ribbons

(e.g. Fragilaria), fans (e.g. Meridion), zigzags (e.g. Tabellaria), or stars

(e.g. Asterionella). A unique feature of diatom cells is that they are

enclosed within a cell wall made of silica (hydrated silicon dioxide) called

a frustule (Museum of Paleontology, California 1990).

Diatoms generally range in size from 2 to 200µm (Grethe et al 1996) and

build intricate hard but porous cell walls (called frustules or tests)

composed primarily of silica (Homer 2002). Sometimes, they can be up to

2 millimeters long, the cell may be solitary or colonial (attached by mucous

filaments or by bands into long chains). Diatoms may occur in such large

numbers and be well preserved enough to form sediments composed

almost entirely of diatom frustules (diatomites) (Boardman, R. S 1987).

11

This siliceous wall can be highly patterned with a variety of pores, ribs,

minute spines, marginal ridges and elevations; all of which can be used to

delineate genera and species. The cell itself consists of two halves, each

containing an essentially flat plate, or valve and marginal connecting, or

girdle band. One half, the hypotheca, is slightly smaller than the other half,

the epitheca (Lipps, J. H. 1981).

Various attempts have been made to classify diatoms, Diatoms

morphology varies although the shape of the cell is typically circular, and

some cells may be triangular, square, or elliptical.

Diatoms are traditionally divided into two orders:

• centric diatoms (Centrales) (now called the Biddulphiales) which

have valve striae arranged basically in relation to a point, an annulus

or a central areola and tend to appear radially symmetrical.

• Pennate diatoms (Pennales) (now called Bacillariales) which have

valve striae arranged in relation to a line and tend to appear

bilaterally symmetrical. The former are paraphyletic to the latter.

The valve face of the diatom frustule is ornamented with pores (areolae),

processes, spines, hyaline areas and other distinguishing features. It is these

skeletal features which are used to classify and describe diatoms, which is

an advantage in terms of palaeontology since the same features are used to

define extant species as extinct ones.

12

Also, (Medlin et al 2004) propose the following classification for the

diatoms

- Bacillaryophyta

- Coscinodiscophytina

- Coscinodiscophyceae (radial centric)

- Bacillariophytina

- Mediophyceae (polar centric)

- Bacillariophyceae (pennate diatoms) The classification system developed by Simonsen (1979) and further

developed by Round et al. (1990) is currently the most commonly accepted.

Diatoms commonly found in the marine plankton may be divided into the

centric diatoms including three sub-orders based primarily on the shape of

the cells, the polarity and the arrangement of the processes. These are the

Coscinodiscineae, with a marginal ring of processes and no polarity to the

symmetry, the Rhizosoleniineae with no marginal ring of processes and

unipolar symmetry, and the Biddulphiineae with no marginal ring of

processes and bipolar symmetry. The pennate diatoms are divided into two

sub-orders, the Fragilariineae which do not possess a raphe (araphid) and

the Bacillariineae which possess a raphe.

13

Fig 2 Image of Centric Diatoms (microfossil image recovery and circulation and

learning education 2012)

14

Fig 3 Image of Pennate Diatoms (microfossil image recovery and circulation and learning

education 2012)

Diatoms have been studied since the late eighteenth century, however the

first real advances in the field came in the early nineteenth century when

diatoms were popular with utilising the emerging improvements in

microscope resolution. Several European workers produced hand

illustrated monographs on diatoms in the late nineteenth century. Notable

amongst these are the works of Cleve, Ehrenberg, Grunow, Schmidt and

Van Heurck. In the early twentieth century fossil diatoms were first studied

and, most famously, Hustedt (1927-1966) produced a taxonomic and

ecological study of diatoms which remains a key reference today. Perhaps

the most complete treatment of diatoms is that of Round et al. (1990).

15

Diatoms can build up and produce oozes or diatomite. Diatoms are good

stratigraphic markers covering the Cretaceous to present, but are mostly

used in Neogene biostratigraphy. The distribution of diatoms depends upon

temperature, salinity and chemical characteristics of water such as pH and

nutrients. Diatoms are useful in paleo-limnology.

16

CHAPTER TWO

REGIONAL GEOLOGY

2.1 INTRODUCTION

The Benin (Dahomey) Basin is a component of a system of West African

peri-cratonic basin (Klemme, 1975; Kingston et al., 1983) formed during

the early stage rifting associated with the opening of the Gulf of Guinea, in

the Early Cretaceous to the Late Jurassic (Burke et al., 1971; Whiteman,

1982).

Basement subsidence were generated as a result of rifting and graben

formation which likely began in the Late Jurassic to Early Cretaceous,

thereby giving rise to massive deposition of non-marine thick sequence of

pebbly sands and continental grits. These sequences along with the

basement complex were tilted and block-faulted in the late Cretaceous

giving rise to a series of grabens and horsts (Omatsola and Adegoke, 1981).

17

Fig. 4 General geological framework of the Dahomey Basin (Modified after Bilman, 1992)

Fig. 5 Geology of the Nigerian Sedimentary Basin (OLANIYI ODEBODE)

The crustal separation which gave rise to the Dahomey Basin was preceded

by crustal thinning and accompanied by a long period of thermally

influenced basin subsidence through the Middle –Upper Cretaceous to

18

Tertiary times as the South American and the African plates entered a drift

phase to accommodate the emerging Atlantic Ocean (Mpanda, 1997). The

basin extends from southeastern Ghana in the west, through southern Togo

and southern Benin Republic to the western flank of Niger Delta in

southwestern Nigeria. The Ghana Ridge, believed to be an offset extension

of the Romanche Fracture Zone, binds the basin to the west while the Benin

Hinge Line, a basement escarpment which separates the Okitipupa

Structure from the Niger Delta basin binds it to the east. The Benin Hinge

Line defines the continental extension of the Chain Fracture Zone (figure

2.1). In the onshore the basin occupies a broad arc-shaped profile area of

about 600 km2 in extent. It attains a maximum width of about 130km in the

N-S axis around the Nigerian/Republic of Benin border. The basin narrows

to about 50 km on the eastern side where the basement assumes a convex

upwards outline with accompanying thinning of sediments. Along the

northeastern margin of the basin where it makes contact with the Okitipupa

high (Ekweozor and Nwachukwu, 1989).

19

Table 1 Stratigraphy of the Eastern Dahomey Basin as coupled by various authors

A good number of scholars including Jones and Hockey (1964); Ogbe

(1972); Omatsola and Adegoke (1981); Billman (1992), Nton (2001);

Elueze and Nton (2004), Ministry of Mines and Steel Development

(MMSD, 2010) etc. have analyzed the stratigraphy of the eastern Dahomey

basin and came up with different classifications as shown in table 1.1. The

major differences in the various classifications are in the area of

nomenclatures and age assignments of the lithological units in the basin.

The paragraphs below give brief descriptions of the lithostratigraphic units

of the Cretaceous to Tertiary sedimentary sequences of the eastern

20

Dahomey basin as put up by Omatsola and Adegoke (1981). The described

units starting from the oldest are the Ise Formation, Afowo Formation,

Araromi Formation, Imo group, Ilaro Formation and Coastal Plain/Benin

Sands Formation. Agagu (1985) however is in agreement with John and

Hockey (1964) and Reyment (1965) that Recent Alluvium overlies the

Coastal Plain Sands.

2.1.1 Ise Formation

The Ise is the oldest formation in Abeokuta Group and unconformably

overlies the Precambrian basement complex. It comprises a basal section

of predominantly conglomerates which gives way to gritty coarse to

medium-grained loose sands interbedded with whitish kaolinitic clays. The

formation is essentially sandy. The maximum thickness of the member is

about 1865m and the age has been given to be Neocomian.

2.1.2 Afowo Formation

Succeeding the Ise formation is the Afowo Formation and is Neocomian -

Albian in age based on its palynomorph content. It indicates the

commencement of deposition in a transitional environment after the entire

basal and continental Ise Formation. The sediments are composed of

interbedded sands, shales and clays, which range from medium to fine

grains in sizes. The formation has been found to be bituminous in both

surface and sub-surface sections.

21

2.1.3 Araromi Formation

The Araromi Formation is the topmost unit of the Abeokuta Group and the

sediments represent the youngest topmost sequence in the group. The

formation is composed of shales, fine-grained sand, thin interbeds of

limestone, clay and lignite bands. It is an equivalent of a unit known as

Araromi shale by Reyment. The shales are grey to black in colour, marine,

and rich in organic matter. The age ranges from Maastrichtian to

Paleocene.

2.1.4 Imo Group

The Imo group consists of the two lithostratigraphic units namely Ewekoro

and Akinbo Formations. As observed at Ewekoro and Sagamu quarries as

well as cored sections at Ibeshe, the Ewekoro Formation directly overlies

the Abeokuta Group. It is made up of grayish white and occasionally

greenish limestone which is sandy toward the base and having a thickness

that varies between 15-30m. This formation is dated Paleocene age.

Akinbo Formation on the other hand is mostly found in the western part of

the Imo Group, directly overlying the Ewekoro Formation. It consists of

thick grey highly fossiliferous shale, which is greenish in colour and

thickly laminated. The age of Akinbo Formation is considered to be

Paleocene.

2.1.5 Ilaro Formation

22

The Ilaro Formation consists of fine to coarse grained sands, clays and

shales with occasional thin bands of phosphate beds. The formation is

Eocene in age.

2.1.6 Coastal Plain/Benin Sand Formation

The Coastal Plain Sand is believed to lie on top of the Ilaro Formation,

though there is no evidence to support this belief. The coastal plain sands

consist of very poorly sorted, clayey, pebbly sands, sandy clay and rare thin

lignite. The age of the Coastal plain sands ranges from Oligocene to

Pleistocene.

2.1.7 Recent Alluvium

This is the youngest unit in the Eastern Dahomey basin. It has been thought

to overlie the Ilaro Formation, though without a convincing evidence. Road

cut exposures between Ofada and Mokoliki around Ogun River show that

the sediments of this Formation are littoral/lagoon sediments which are

mostly clays and loose sands, with occasional pebbles.

23

Fig 6 - OUTCROP GEOLOGY OF THE EASTERN DAHOMEY BASIN (OLANIYI ODEBODE)

25

CHAPTER THREE

METHODOLOGY

Methodology deployed for study site: Epe lagoon (2°50′-4°10′N, 5°30′ -

5°40′E).

-Field Work

-Sample Preparation

-Preparation & Viewing Micro-Paleontological slides under Optical

Microscope

3.1 Field work

The study was carried out in the month of April 2015. Ten (10) sampling

points were established for this study along the Epe lagoon, each with its

longitude and latitude positions. Sample locations were taken using a

Global Positioning System (GPS).

Ten sediment samples were collected from the sample points in the lagoon

for micro-paleontological studies.

Sediment samples at each sample point were collected using a sample

grabber. The sediments were collected at the base of the lagoon at each

sample point with corresponding latitude and longitude. The sediments

were emptied into polyethylene bags and preserved with formalin. The

essence of formalin was to preserve the microfossils present in the

sediment.

26

S/N Sample Points Co-ordinates Depth (m)

Ph Temp (Celcius)

PPM

Diss.Oxygen (mg/l)

(Ns) Sediment Colour/Texture

1

Location 21

Lat; 063322.2N

Lon; 0040057.8E

2

7.58

31.6

72

18.7

140

-

2

Location 8a

Lat; 063448.9N

Lon; 0035936.5E

6

7.0

32.0

-

-

-

Slightly

Brackish Water

3

Location 8b

Lat; 063433.9N

Lon; 0035930.1E

7

7.1

31.9

-

-

-

Brackish water

4 Location 9 Lat; 063442.3N

Lon; 0040018.8E

7

7.3

32.1

68

1.0

135

Brackish water

5 Location 10 Lat; 063413.7

Lon; 0040057.8E

3

7.4

32.0

69

16.4

137

-


Lon; 0040132.5E

4

7.55

32.1

72

30.1

144

Dark grey

Very Fine Silt


Lon;0040222.3E

2.2

7.57

32.1

72

-

143

Dark-Grey

Very Fine Mud


Lon; 0040208.7E

2.5

7.77

31.9

72

-

143

-


Lon; 004133.6E

2

7.6

31.6

72

14.9

141

Dark grey

Very Fine Silt


Lon; 0035959.2E

2

7.1

31.9

71

1.0

141

-


Lon; 035920.0E

2.5

7.48

31.8

68

17.0

131

-

Table 2 showing data collected from different sample points at the Epe Lagoon

3.2 Sample Preparation

Out of 20 samples collected, 10 samples were selected as representative

samples for micro-paleontological studies.

3.2.1 Autoclave water (Preparation of distilled water)

27

Equipment: Autoclave Machine

Materials: Conical Flask, Foil Paper and Cotton Wool

1. Water was put into the conical flask and air-tight with cotton wool

and foils paper to prevent evaporation & contamination.

2. The conical flask was placed into the autoclave machine for

duration of 20minutes to reach a temperature of 125 degree Celsius

3. The water was brought out and allowed to cool; the end product

was pure, clean distilled water.

3.2.2 Dissolution of Sediments

Equipment: Weigh Balance

Materials: Conical Flask, Distilled Water, Palette and Cotton Wool

1. Exactly 2g of sediment (from each of the 11 different samples) is

chopped off using a scalpel and measured into 11 different conical

flasks; each labeled appropriately while using a weigh balance to

get the accurate measurement.

2. Distilled water is measured at varying ratios up to the top of the

conical flask to allow sediments dissolve properly.

3. This solution is left for 24hours to dissolve properly and settle.

4. After 24hours, the sediment is agitated to mix, and then allowed to

settle briefly then it was decanted into bottle containers and

labeled with their corresponding Locations.

28

Fig 7 Image of Preparation and Dissolution of Samples

3.2.3 Acid Clean

Equipment: Hot Plate

Material: Conc. HNO3 (Nitric Acid), Distilled water, Conical Flask, Lab

Coat, Gas Masks, Hand Gloves.

1. The 10 different samples in bottle containers were poured into 10

different conical flasks each labeled appropriately; the samples fill

the conical flasks half-way.

2. Concentrated HNO3 was added to the sample solutions to fill

conical flasks up to a quarter-full

3. Hotplate was allowed to warm gently at moderate heat temperature,

and then the 11 different solutions were placed gently on the

hotplate to boil

29

4. The technique was to allow the solution boil & evaporate to half of

its original measurement at a constant heat temperature in

approximately 4 Hours.

5. After 4hours of constant boiling and evaporation, distilled water

was added to fill up the evaporated portion and subsequently left

for 8hours.

6. after 8 Hours, the solution was decanted to allow rested sediments

remain in the conical flask and waste water was disposed safely

because of the hazardous nature of the solution and chemical used.

7. Distilled water was added again to fill up decanted portion, the

essence; to clean & wash the solution of impurities, this new

solution is left for another 8 hours.

3.3 Centrifuge of Samples

Equipment: Centrifuge Machine

Materials: Centrifuge Tube

1. The settled solution was poured into a centrifuge tube, total number

of centrifuge tubes were 10 as a result of 10 samples.

2. These tubes were placed inside the centrifuge Machine at a speed

of 50rounds for 10 Minutes

3. After completion of centrifuge rounds, the 11 samples were

brought out from machine and placed on a wooden holder.

30

3.4 Preparation & Viewing Micro-Paleontological Slides under

Microscope

Equipment; Optical Microscope, Photo Micrograph

Material; Slides, Dropper, /Beaker, Hand Gloves, Distilled water

the standard smear slide preparation is the same as described by Bown and

Young (1998), the settling preparation follows Geisen et al. (1999). The

steps of the settling preparation method are summarized as follow:

1. The centrifuged samples were used to prepare slides to be viewed

under the optical microscope

2. A dropper was used to take tiny amounts of samples from the tube,

this tiny amount of samples were placed on the slides and enclosed

with a cover plate.

3. The dropper is washed thoroughly after use for a particular location

samples to avoid contamination of samples.

4. This process was used to create the slides and to continually view

under the optical microscope to determine the abundance and

presence of microfossils.

5. Viewing was done using microscope lense x 40.

31

CHAPTER FOUR

4.1 RESULTS AND INTEPRETATION

The diatoms were of special interest in the entire microfossil content of the

Epe Lagoon. Thus, a total of 11 species of diatoms were identified in the

Epe lagoon, 8 centric diatoms and 4 pennate diatoms lettered A to K.

A – Aulacoseira

B – Amphora

C – Cyclotella striata

D – Coscinodiscus

E – Cocconeis placentula

F – Nitzschia

G – Conscinodiscus lineatus

H– Cymatopleura

I – Synedra

J– Fragilaria

K – Diploneis

4.2 IDENTIFICATION AND MORPHOLOGY

The number of species of diatoms is enormous; (Helmcke 1961) cites that

of some 100,000 species only some 10,000 may be recognized as valid.

32

A - Aulacoseira; It is a centric diatom; the frustules of Aulacoseira are

linked to one another by spines to form filaments. Cells are typically seen

in girdle view, because of the deep valve mantle. Cells often form colonies

and, depending on the species, may be joined by linking spines. The shape

of the linking and separation spines and relationship between spines and

striae are important characters that distinguish species within Aulacoseira

(Spaulding S et al 2008). Some of the species found in the Epe Lagoon are

Varida, Undulata, Granulata Var. Angustissima,

B – Amphora; It is a centric diatom; The Valves of amphora are

asymmetrical to the apical axis and symmetrical to transapical axis. On the

dorsal margin, the valve mantle is deeper than on ventral margin. As a

result, the frustule is wedge-shaped, similar to a section of an orange

(Spaulding, S. 2011).

C – Cyclotella Striata; It is a centric diatom; Cells are short and drum-

shaped and are rarely found in chains. The valve view is most commonly

seen. Valves are usually circular (sometimes elliptical) with a tangential or

concentric undulation of the valve face (rarely flat).

D – Conscinodiscus; This are very large centric diatoms, Cells are disc-

shaped, cylindrical or wedge-shaped, and solitary. Distinct rosette of large

areolae in the center of the valve, numerous chloroplasts.

33

E– Cocconeis Placentula; Valves are elliptic to linear-elliptic and

relatively flat. The raphe valve has a narrow axial area and a small circular

or oval central area.

F– Nitzschia; Nitzschia possesses an eccentric raphe, positioned in a canal

along one valve margin. The raphe systems within a frustule are positioned

on opposite, in the manner of line symmetry.

G – Conscinodiscus Lineatus; they are photosynthetic

H– Cymatopleura; Cells are linear, panduriform in valve view and

somewhat rectangular in girdle view. The valve surface is flat.

The raphe runs around the perimeter of the entire valve and is elevated by

a shallow keel (Hendey 1964).

I– Synedra; They are Centric, Cells approximately rectangular in girdle

view, typically long and thin attached by mucilage pads at the base to form

radiate colonies. There are two long plastids lying against the girdles and

overlapping slightly onto the valve face. In unhealthy material, these

plastids may split up, giving the appearance of many small discoid plastids.

J– Fragilaria; They are pennate; Valves are lanceolate, with an inflated

central margin. Valve apices are rounded to capitate. Spines are positioned

on the margin, a spine present at the end of a stria. Frustules are joined in

ribbon-like colonies (W. Smith 1980).

34

K– Diploneis; They are pennate; Frustules of Diploneis are typically

elliptical to panduriform, with bluntly rounded apices. Each valve

possesses two longitudinal canals, one on each side of the raphe. The canals

are positioned within the silica cell wall and open to the exterior through

pores, but lack openings to the interior of the cell.

4.2 PHOTOMICROGRAPH OF SAMPLES A-K

Plate 1; A – Aulacoseira

35

Plate 2; B - Amphora

Plate 3; C –Cyclotella Striata

36

Plate 4; C - Cyclotella and D- Conscinodiscus

Plate 5; E - Cocconeis placentula and C - Cyclotella Striata

37

Plate 6; F - Nitzschia

Plate 7; I-Synedra Acus

38

Plate 8; H- Cymatopleura

Plate 9; J - Fragilaria

39

4.3 PERCENTAGE COMPOSITION OF DIATOM SPECIES

Location 8

Diatoms Species Percentage composition (%)

Aulacoseira 44.1

Amphora 10

Cyclotella Striata 20

Conscinodiscus 15

Nitzsichia 9.6

Cocconeis Placentula 1

Cymatopleura -

Synedra -

Fragilaria -

Diploneis -

Table 3 for Location 8

Location 10


Aulacoseira 50.4

Amphora 13.7

Cyclotella Striata 15.4

40

Conscinodiscus 4.2

Nitzsichia 16.3

Cocconeis Placentula -

Cymatopleura -

Synedra -

Fragilaria -

Diploneis -


Location 24


Aulacoseira 52.1

Amphora 3.2


Conscinodiscus 18

Nitzsichia 3.3

Cocconeis Placentula 2.3

Cymatopleura -

Synedra -

Fragilaria -

41

Diploneis 1


Location 9


Aulacoseira 41.4

Amphora 2.2


Conscinodiscus 14.5

Nitzsichia 1.6


Cymatopleura -

Synedra 1

Fragilaria -

Diploneis -

Table 6 for location 9

Location 11


Aulacoseira 40.2

Amphora 2.5


42

Conscinodiscus 13.2

Nitzsichia 4.9


Cymatopleura -

Synedra 6.2

Fragilaria -

Diploneis 3.2


Location 19


Aulacoseira 80.2

Amphora 2.1


Conscinodiscus 0.5

Nitzsichia -


Cymatopleura -

Synedra -

Fragilaria -

43

Diploneis -


Location 23


Aulacoseira 42.1

Amphora 9.9


Conscinodiscus 7.1

Nitzsichia 4.1


Cymatopleura 10.3

Synedra -

Fragilaria 8.2

Diploneis -

Table 9 for location 23 Location 21


Aulacoseira 48.8

Amphora 5.9


44

Conscinodiscus 6.9

Nitzsichia -


Cymatopleura 3.2

Synedra 5.1

Fragilaria 1.4

Diploneis 1.5


Location 20


Aulacoseira 40.5

Amphora 4.9


Conscinodiscus 9.9

Nitzsichia 8.1


Cymatopleura 3.5

Synedra 2.9

Fragilaria 2.3

45

Diploneis 3.2

Table 11 for location 21

Location 12


Aulacoseira 46.2

Amphora 4.1


Conscinodiscus 15.5

Nitzsichia 1.8


Cymatopleura -

Synedra 8.2

Fragilaria -

Diploneis -


46

DISCUSSIONS

Diatom assemblages and individual species provided reliable indicators of

stream conditions throughout the Epe lagoon. A multi-dimensional

ordination showed that dissolved oxygen, alkalinity, temperature, depth

and substratum conditions were the most significant environmental

determinants influencing diatom community structure in the region. While

floater organisms may infer the climatic conditions, the benthic organisms

infer the depositional environment and substratum condition, whilst the

centric diatoms are found at the top of the stream sediments the pennate

diatoms are found at the depth of the stream sediment.

Thus, the most abundant specie of the centric diatom was the Aulacosiera

and Cyclotella while the most abundant specie of the pennate diatoms is

the Synedra and Cymatopleura.

The results show that the Aulacoseira and its many varieties constitute the

most dominant diatom throughout the Epe lagoon occurring in all Ten (10)

sample locations with very high abundance, this species are recognized as

good indicators of pollution as well as the amphora specie which was

scarcely found, these diatoms are referred to as pollution tolerant species

(S.A. Akinyemi 2007).

The high abundance of the aulocoseira brings to the fore the authenticity

of lagoon as a fresh water lagoon.

47

The second most abundant diatom is the cyclotella which were found at

varying depths ranging 2-2.5m indicates an organic-enriched lagoon

between Latitude 063423.3N and Longitude 035920.0E. The presence of

these diatoms suggests eutrophication (Mau, D.P., 2002)

Similarly, mid to high brackish water / marine forms included

Coscinodiscus, According to (Onyema 2006), the Synedra specie suggest

fresh water situation / low - moderate level nutrient levels/ moderate

organic pollution.

The pennate datoms; Fragilaria, Diploneis, Mesidictyopsis occurred in

assemblages together with centric diatom; Aulacoseira islandica at the

furthest part of the Epe lagoon study area which suggests that the different

species types exist in different parts of the deposits, which reflect temporal

and spatial variations in water depth, dissolved oxygen and salinity.

CONCLUSION

The existence of different species of diatoms in different parts of the study

area of the lagoon lead to the conclusion that the various diatoms specie

were tolerating the change in pH, salinity and dissolved oxygen of the

environment.

RECOMENDATION

48

I strongly recommend that the Micro-paleontological Study of Epe lagoon

should be carried out as often as possible; the micro-paleontological

content of the Epe lagoon is less known.

If this can be ensured, it will pave an easy way for subsequent research on

that field.

49

REFERENCES

A.G. Fischer and S. Judson (eds), Petroleum and Global Tectonics.

Princeton, New Jersey, Princeton Univ. Press, pp. 251-304.

Bignot, G., (1985), Elements of Micropaleontology, Graham & Trotman

Ltd.

Billman, A., (1992), Offshore stratigraphy and paleontology of the

dahomey basin (benin embayment), West Africa. NAPE Bull., 7:

121-130.

Boardman R. S, Cheetham, A. H. and Rowell A. J. (Editors) (1987), An

advanced college-level text on fossil invertebrates with exellent

descriptions and good illustrations. Blackwell Science, 238 Main

St., Cambridge, MA 02142. p713.

Brasier M. D, (1981), Microfossils George Allen & Unwin.

Burke, K., Dessauvagie, T. F. J., & Whiteman, A. J. (1971), Opening of

the Gulf of Guinea and geological history of the Benue depression

and Niger Delta. 233, 51-55.

Clement Aghatise , Ikharo E.A (2011), The malaco-faunal characteristics

of the ‘sandwiched’ Epe Lagoon Researcher 3(10, 15-21.

Edokpayi CA, Nkwoji JA (2007), Annual changes in the physicochemical

and macrobenthic invertebrate characteristics of the Lagos lagoon

sewage dump site at Iddo, Southern Nigeria. Ecol. Environ.

Conserv. 13(1): 13 – 17.

Ekweozor CM, Nwachukwu JI (1989), The Origin of Tar Sand of

Southwestern.

Elueze, A.A. and M.E. Nton, (2004), Organic geochemical appraisal of

limestones and shales in part of Eastern Dahomey basin,

Southwestern Nigeria. Mining Geol., 40: 29-40.

Federal Ministry of Mining, Abuja Nigeria (2010).

50

Helmcke J.G (1961), Versuch geiner getstanalyse an diatomeenschalen

Rec. adv bot pg 216 -221.

Jones D.J and Hockey R.D (1964), the geology of part of S. W. Nigeria,

Geol. Survey Nigeria, Bull 31, 87p.

Jones D. J (1956), Introduction to Microfossils (Harper & Brothers )

(Also 1969 edition, Hafner Pub. Co).

Kingston, D.R., Dishroon, C.P. and Williams, P.A., (1983), Global Basin

Classification System. AAPG Bull, Vol. 67, pp. 2175-2193.

Klemme, H.D, (1975), Geothermal Gradients, Heat flow and Hydrocarbon

Recovery.

Kusemiju, K, Oke K.L, A.M.A. Imevbore and T.A. Farri (1988),

Strategies for effective management of water hyacinth in the creeks

and lagoons of south-western Nigeria ., 39-45.

Lipps, J. H. (1981), What, if anything, is micropaleontology?

Paleobiology, vol. 7, p. 167-199. An essay on the history, use, and

potential of microfossils in paleontology.

Microfossil image recovery and circulation and learning education (2012).

Mau, D.P., (2002), selected water-quality characteristics in the Lake Olathe

watershed [abst.], in Proceedings of the 11th Annual Kansas

Hydrology Seminar, November 22, 2002, Manhattan, Kansas:

American Institude of Hydrology--Kansas Section and Association

of Engineering Geologists--Kansas City/Omaha Section, 1 p.

Museum of Paleontology , California United States of America (1990).

Medlin L.K. & Kacmarska. I (2004), Evolution of the diatoms, V.

Morphological and cytological support for the major clades and a

taxonomic revision. Phycologia, 43: 245–270.

Mpanda, S. (1997), Geological development of East African coastal basin

of Tanzania: Acta Universities Stockholmiensis, v. 45, 121p.

51

Nwankwo, D.I. and Akinsoji, A. (1989), The Benthic Algal Community of

a Sawdust Deposition Site in Lagos Lagoon , International Journal

of Ecology and Environmental Sciences. 15: 197-204.

Ogbe, F. G. A., (1972), Stratigraphy of strata exposed in the Ewekoro

quarry, western Nigeria. Cont. on African Geology Ibadan (1970).

Omatsola M.E. and Adegoke S. O. (1987), Tectonic evolution and

Cretaceous stratigraphy of the Dahomey Basin Jour. Min. Geol. Vol.

18[1], pp. 130- 136.

Onyema, I.C (2006), Phytoplankton Bio-indicators of Water Quality

Situations in the Iyagbe Lagoon, South-Western Nigeria Department

of Marine Sciences, University of Lagos, Akoka, Lagos, Nigeria.

Smol, J.P. and Stoermer, E.F. (2010), The Diatoms: Applications for

Environmental and Earth Sciences. Second Edition, Cambridge

University Press. 667 p.

Spaulding, S and Edlund, M. (2008), Aulacoseira. In Diatoms of the

United States from http://westerndiatoms.colorado.edu/

taxa/genus/Aulacoseira

Spaulding, S. (2011), Amphora. In Diatoms of the United States.

Valentina Sattarrova and Antonio V. Artemova (2001), Geochemical and

micropaleontological character of Deep-Sea sediments from the

Northwestern Pacific near the Kuril–Kamchatka Trench.

Webb, J.E. (1958), The Ecology of Lagos lagoon. 1: The lagoons of the

Guinea Coast. Philosophical Transaction Royal Society London.

Ser B: 241-283.

W. Smith Lange-Bertalot (1980), Fragilaria tenera.

olamide olabisi final year project

Documents