AQUATIC ENVIRONMENTAL SURVEY (FAP 413)

BY

SALOME THOMAS

REG NO: - 20U/140032

SUBMITTED TO THE COURSE LECTURER DEPARTMENT OF

FISHERIES AND AQUACULTURE, ADAMAWA STATE UNIVERSITY

MUBIIN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE

AWARD OF FISHERIES AND AQUACULTURE

CHAPTER ONE:

INTRODUCTION
Survey of Aquatic Environment

An aquatic ecological survey is crucial for fisheries, emphasizing the

importance of planning. As the saying goes, "he who fails to plan, plans to fail."

This survey involves proper planning in both capture and culture fisheries.

Definition of Surveying

Surveying is the art of determining the relative position of distinctive features

on the surface of the earth or beneath the earth. It involves measuring distances,

directions, and elevations to accurately determine terrestrial or three-

dimensional positions of points.

Types of Surveys

Surveys fall into two major groups:

1. Geodetic Survey: Deals with the measurement of the Earth's surface.

2. Plane Survey: Deals with the measurement of smaller areas.

Branches of Surveying

Some branches of surveying include:

1. Cadastral (Land) Survey

2. Topographic Survey
3. Engineering Survey
4. Hydrographic Survey
5. Photogrammetric Survey
6. Mine Survey
7. Satellite Survey
Definition of Ecology

Ecology is the scientific study of the relationships between organisms and

their environment. It examines the interactions between living things and their

physical environment.

Aquatic Ecology

Aquatic ecology studies the relationships between aquatic organisms and

their physical, chemical, and biological environment. It encompasses all marine

and freshwater ecosystems.

Aquatic Environment

The aquatic environment refers to the ecosystem that exists in and around

water bodies. It includes the physical, chemical, and biological components that

interact and influence one another.

Objectives of the Course

1. To study the aquatic environment.

2. To learn how to carry out survey and leveling.

3. To identify the different instruments for survey and leveling.

 CHAPTER TWO

What is Levelling in Surveying?

Levelling in surveying is the process of determining the difference in

elevation between two or more points on the Earth's surface. It involves

measuring the vertical distance between a reference point (known as the datum)

and a point of unknown elevation. It is a fundamental technique in civil

engineering that ensures accurate elevation data for construction, roadwork,

drainage systems, and other infrastructure projects. The goal of levelling is to

establish a reference point or benchmark to maintain uniformity in design and

execution.

By using different types of levelling instruments like rods and dumpy

levels, surveyors can achieve precision in their work, ensuring project stability

and compliance with design specifications. This essential method plays a

critical role in creating reliable and sustainable structures.

What is Reduced Level in Surveying?

Reduced Level in surveying refers to the vertical distance of a point from

a reference datum, typically the sea level or a chosen benchmark. It is used to

determine the height of different points on a site relative to the established base

level. In levelling in civil engineering, reduced level is crucial for planning

elevations, designing drainage systems, and ensuring accurate construction

measurements. By using reduced levels, surveyors can make informed decisions

about the topography of the land.

Types of Levelling in Surveying

Here is a list of crucial types of levelling in surveying that every civil engineer

should know.

 Simple Levelling

It is the most basic method, where the instrument is set up between two

visible points, ideal for short distances and provides a simple way to

measure height differences in nearby areas. This type of levelling in civil

engineering is often used for small-scale projects.

 Differential Levelling

This method involves transferring levels between two distant points using

multiple setups. It is widely used for precise elevation measurements in

large-scale projects like roadways and dams. Differential levelling is one

of the most reliable types of levelling in surveying, ensuring accuracy

across long distances.

 Fly Levelling
 This type of levelling connects benchmarks over long distances.

Commonly used in preliminary surveys, it is an efficient method for

establishing temporary benchmarks quickly during construction.

 Profile Levelling

This type creates elevation profiles along a fixed line, such as a roadway

or pipeline path. It provides data for designing gradients and ensuring

proper flow in infrastructure projects.

 Reciprocal Levelling

This method is used when levelling across obstacles like rivers or valleys.

Measurements are taken from both ends to reduce errors caused by

distance and atmospheric conditions, ensuring accurate results.

 Barometric Levelling

This advanced method uses atmospheric pressure differences to calculate

elevations. It is less precise but useful in rugged terrains where traditional

instruments are challenging to use.

 Trigonometric Levelling

By measuring vertical angles and distances, this method calculates

elevations. It is often used in hilly areas and is a valuable tool in modern

surveying. Trigonometric levelling plays a significant role in terrain-

specific and large-scale projects.

 Dumpy Level
 It is a simple yet vital instrument used in direct levelling to establish

height differences. It is ideal for construction sites and infrastructure

development.

 Automatic Level

This instrument self-adjusts to maintain accuracy, making it easier and

faster for surveyors to measure elevations, especially on uneven terrains.

 Tilting Level

This allows minor adjustments for accuracy, making it versatile in

situations requiring precision, such as building layouts or drainage

systems.

 Direct Levelling

It is the most commonly used method, where a level and staff are

employed to measure vertical differences between points.

Principles of Levelling in Surveying

These are essential to ensure accurate and reliable measurements in land

surveying. Here are some of the vital principles that you should know.

 Horizontal Line of Sight

In levelling in civil engineering, measurements are made using a

horizontal line of sight to minimize errors due to slope or curvature. The

instrument used, such as a level or a theodolite, must be set up correctly

to maintain this reference.

 Use of Instruments

Various instruments like the dumpy level, automatic level, and tilting

level are used in levelling. These instruments help measure height

differences and ensure the horizontal line of sight is maintained

throughout the process.

 Benchmarking

Surveyors establish reference points or benchmarks at known elevations.

These benchmarks serve as the foundation for all levelling operations,

ensuring consistency and accuracy across the project.

 Compensation for Instrument Errors

Instruments need to be calibrated regularly to account for minor errors

that could distort results. This principle is essential in maintaining the

accuracy of the data obtained during levelling in surveying.

 Closure of Levelling

The final principle involves checking the accuracy of the measurements

by closing the levelling loop. This is done by returning to the starting

point to confirm that the initial measurements align with the final results,

ensuring there are no significant errors in the procedure.

Objectives of Levelling in Surveying

Objectives of levelling in surveying ensure the proper alignment and planning

of construction projects, making it essential for precision in civil engineering.

Explore the crucial objectives:

 Establishing relative heights of points to ensure accurate construction and

design.

 Creating a horizontal reference line, crucial for precise measurements in

levelling in civil engineering.

 Determining elevations in relation to a known benchmark, ensuring

reliability in surveys.

 Supporting construction projects by aligning structures like roads and

bridges with the natural landscape architecture.

 Assisting in the creation of contour maps to represent accurate

topographical details.

Instruments Used in Levelling Surveying

Each levelling instrument serves a unique purpose and plays a crucial role in

ensuring the accuracy of elevation measurements. Understanding the

specific requirements of a project helps in selecting the appropriate instrument

for the project. Below are some of the most commonly used types of levelling

instruments.

 Auto Level
 It is an advanced version of the dumpy level that automatically adjusts to

ensure the instrument is perfectly horizontal. This feature reduces human

error and increases accuracy, making it ideal for larger surveying projects

like infrastructure developments. It is typically used for establishing

straight lines and elevation differences.

 Dumpy Level

It is one of the most widely used levelling instruments in surveying,

which is a simple and precise tool consisting of a telescope mounted on a

horizontal axis. It is used to measure the difference in height between

various points and to establish a horizontal reference line. The dumpy

level is particularly helpful in construction of roadworks.

 Digital Level

This instrument uses electronic sensors to measure height differences and

display the results digitally. This type of level is known for its high

precision and ease of use. It’s especially valuable for surveying tasks

where detailed measurements are required.

 Theodolite

While primarily used for angle measurement, theodolite can also be

employed in levelling surveys to measure horizontal and vertical angles

for determining the slope or difference in elevation. It is a versatile

instrument often used in large-scale surveying operations.

 Tilting Level
 It is similar to the dumpy level but features a tilting mechanism that helps

fine-tune the horizontal adjustment. This instrument is suitable for precise

horizontal alignment and is commonly used in large-scale civil

engineering projects.

 Levelling Staff

It is not exactly an instrument in itself but works in tandem with the

above levelling instruments to measure vertical height differences. Made

from a telescopic or graduated pole, the levelling staff is placed at the

point being measured, and the surveyor reads the height using the

levelling instrument.

Methods In Levelling in Surveying

The Levelling method plays a significant role in levelling in civil engineering,

depending on the requirements of the project. Below are some of the most

commonly used methods in surveying.

 Direct Levelling

One of the simplest methods, where a levelling instrument is used to

establish a horizontal line of sight. The difference in height between two

points is measured using a levelling staff. This method is commonly used

for short-distance measurements.

 Differential Levelling
 In differential levelling, the difference in elevation between two or more

points is measured by using a levelling instrument and staff. This method

helps in determining the reduced level (RL) at different locations, often

used in creating profiles and cross-sections for construction.

 Fly Levelling

It is a quick method used for rough levelling. It is typically employed to

establish approximate heights over long distances. Although less precise,

it is helpful in initial survey work before finer adjustments are made with

other methods.

 Trigonometric Levelling

This is used to determine the height difference between points based on

observed angles and distances. It is especially useful when measuring

over long distances or when physical access is difficult.

2.0 LEVELING

Levelling is a branch of surveying, the object of which is to establish or

verify or measure the height of specified points relative to a datum. Levelling is

a fundamental surveying technique used to determine the difference in elevation

between two or more points on the Earth's surface. It is widely used in geodesy

and cartography to measure geodetic height, and in construction to measure

height differences of construction artifacts. It is also known as spirit levelling

and differential levelling. This deals with the determination of the relative
heights of points on the earth’s surface. The process of this determination is

either direct or indirect.

2.1 SOME TERMS USED IN LEVELLING OPERATIONS

1. Bench mark (BM): it is a fixed point on the earth’s surface whose level

above ordnance datum is known.

2. Ordnance Datum (OD): it is the mean sea level to which all other levels

are related.

3. Back sight (BS): is the first sight taken after the level has been set up. A

sight taken to a point whose height is known or can be calculated.

4. Foresight (FS): The last sight taken. A sight taken to a point whose

height is required to carry on the line of level.

5. Intermediate Sight (IS): it is any other sight taken.

6. Reduced Level (RL): calculated level of a point above or below the

datum.

7. Height of Instrument (HI): The height of the line of collimation above

the datum.

8. Line of Collimation (LM): It is an imaginary horizontal line drawn

between two points. 9. Rise and fall: The difference is height or is level

between two is referred to as a rise or fall.

9. Change Point (CP): the point at which both a foresight and then a back

sight are taken.

2.2 LEVELING INSTRUMENTS

These include: A Level e.g. theodolite, transit dumpy level (automatic

level),e.t.c.

A staff. Devices for angle measurements e.g. Graphometer, magnetic compass,

prismatic compass, orientation compass. Chain or tape. Pegs, arrows and

ranging poles

2.3 LEVELLING INSTRUMENT AND THEIR FUNCTION

THEODOLITE

A theodolite is a precision optical instrument for measuring angles between

designated visible points in the horizontal and vertical planes. The traditional

use has been for land surveying, but they are also used extensively for building

and infrastructure construction, and some specialized applications such as

meteorology and rocket launching.

TRANSIT DUMPY LEVEL

A level is an optical instrument used to establish or verify points in the

same horizontal plane in a process known as levelling, and is used in

conjunction with a levelling staff to establish the relative heights levels of

objects or marks. It is widely used in surveying and construction to measure

height differences and to transfer, measure, and set heights of known objects or

marks.

GRAPHOMETER

The Graphometer, semicircle or semi Circumferentor is a surveying

instrument used for angle measurements. It consists of a Semicircular limb

divided into 180 degrees and sometimes subdivided into minutes. The limb is

subtended by the diameter with two sights at its ends. In the middle of the

diameter a "box and needle" (compass) is fixed. On the same middle the alidade

with two other sights is fitted.

TAPE

A tape measure or measuring tape is a flexible ruler used to measure size or

distance.

PRISMATIC COMPASS

Prismatic compass is a navigation and surveying instrument which is

extensively used to find out the bearing of the traversing and included angles

between them, waypoints (an endpoint of the course) and direction or A

prismatic compass is a type of surveying instrument used for measuring

directions and angles between reference points. It is also known as a "prismatic

surveying compass" or "prismatic direction finder".

RANGING POLE

A ranging rod (or range rod) is a surveying instrument used for marking the

position of stations, and for sightings of those stations, as well as for ranging

straight lines. Initially these were made of light, thin and straight bamboo, or of

well-seasoned wood such as teak, pine or deodar.

GUNTERS CHAIN

Gunter's chain (also known as Gunter’s measurement) is a distance measuring

device used for surveying. Or Gunter's Chain is a measuring device used in

surveying to measure distances and lengths. It is a chain of 100 links, each link

being 7.92 inches (20.116 cm) long.

MAGNETIC COMPASS

The magnetic compass is the most familiar compass type. It functions as a

pointer to "magnetic north", the local magnetic meridian, because the

magnetized needle at its heart aligns itself with the horizontal component of the

Earth's magnetic field. The magnetic field exerts a torque on the needle, pulling

the North end or pole of the needle approximately toward the Earth's North
magnetic pole, and pulling the other toward the Earth's South magnetic pole.

The needle is mounted on a low-friction pivot point, in better compasses a jewel

bearing, so it can turn easily.

2.4 HOW TO CARRYOUT LEVELLING

A direct measurement is one taken up or down from one point to another

which may be made by spirit level, water level, and brick layer’s level or

indirect measurement made depression from one point to the other. Data from

levelling operations are used to prepare topographical plans and map. These

drawings show the main physical features on the ground, such as rivers, lakes,

roads,etc as well as the changes in elevation between land forms such as valleys

and hills( called vertical reliefs).Plans are usually large-scale (e.g. 1cm for

100m) drawings; maps are small-scale (e.g. 1cm for 200m) drawings. A plan

shows information on farm features such as dikes, ponds, drainage canals or

outlets structures. Topographical map shows the fish farm site. These are very

important in fish farm construction. They help guide in choosing a site, planning

the fish farm, and designing the structures that are needed for the farm. They

also guide in the layout, so that one can follow the plan that has been made for

the fish farm, and build the structures on it correctly

2.5 SURVEY
 A survey is the process of collecting and analyzing data about a specific

area or population. In the context of surveying, it involves measuring and

mapping the Earth's surface to gather data about its shape, size, and features.

Surveying is the branch of applied mathematics which deals with

measuring and recording of the size and shape of any portion of the earth’s

surface, and the delineation of the same in a map or plan. It deals with the

setting out of works such as roads, railways, waterworks, drainage schemes etc

and the calculation of areas and volumes. It may be taken to include levelling

i.e. determination of the relative heights of different points on the earth surface.

TYPES OF SURVEYING

1. Trigonometrical surveying : - This is for the preparation of maps of large

extents of territory

2. Land surveying: - this is ranging from the land division system and

extensive topographical surveys and work for boundary commission to

small ones such as farms and estates.

3. Hydrographical surveying: - ranging from coast surveys to plans for harbour

works.

4. Engineering location surveying: - For the construction of highways,

railways and various public works.

5. Preliminary or parliamentary surveys: - This is in connection with a

projected scheme such as the construction of a railway or a waterworks.

6. Exploratory surveying: - This is for geological, engineering and mining

enterprises including archaeological expeditions.

7. Environmental survey: - his is survey carried out for forest and water

parameters.

2.6 SURVEY IN POND CONSTRUCTION

Through topographic survey, the proposed site is inspected and

professionally approved. The water, soil and other parameters are determined.

Using levelling instrument, the topography of the site is ascertained and the area

to be dug/ excavated or filled is pegged out with the use of lines.

TOPOGRAPHIC SURVEY

A topographic survey is a type of survey that measures and maps the

natural and man-made features of an area, including elevation, relief, and land

cover. Or Topographic survey Topographic survey is carried out at the site

selected for a fish farm project. This is based on a convenient datum marked

with a temporary bench mark (TBM) at the site. There are several methods

used for topographic surveys, depending on the nature and size of the land

required for the project. The following methods are the most commonly applied

for topographic surveying:

i. Gridding
 ii. Plane tabling

iii. Cross-section method with traverse survey

iv. Radiating lines method with traverse survey

v. Tachometry.

Methods (i) and (ii) are ideal on relatively flat land, while methods (iii) and (iV)

may also be used but are best suited to hilly terrain or in narrow long valley.

The following topographic maps and plans are generally needed for a

project:

i. Index or location map

ii. Boundary map

iii. Contour map

iv. Cross and longitudinal section and

v. Land map

i. Index or Location Map

An index or location map is a small-scale map that shows the location of the

project area in relation to surrounding areas, such as cities, towns, or landmarks.

ii. Boundary Map

A boundary map is a map that shows the property boundaries, including the

location of property lines, corners, and other reference points.

iii. Contour Map

A contour map is a topographic map that shows the shape and elevation of the

land using contour lines, which connect points of equal elevation.

iv. Cross and Longitudinal Section

A cross and longitudinal section is a graphical representation of the terrain,

showing the elevation and shape of the land along a specific line or axis.

v. Land Map

A land map, also known as a cadastral map, is a map that shows the ownership

and boundaries of land parcels, including information such as property owners,

parcel numbers, and zoning designations.

General Information and data needed for topographic survey

A. The Project site.

 Location

 Accessibility

 Communication

 Power supply

 Land status
  Existing improvements

B. Hydrological data

 Design flood

 Runoff

 Ground water potential

C. Meteorological data

 Mean monthly temperature

 Mean monthly rainfall

 Mean monthly evaporation

 Mean monthly humidity

 Mean monthly sunshine

 Mean monthly wind speed and prevailing direction

VIRSUAL SURVEY

This is also called reconnaissance survey. It is the preliminary inspection

of an area to be surveyed. It is a see-for-yourself walk-over of the ground to be

used for a fish pond or a fish farm. It is first done with a view to visualise the

work to be done. It is the venture taken to note and identify all the parameters to

be measured or surveyed. It is a rough sketch of the field or fields in which all

positions and stations are made in the field book. It is preliminary work done

whereby the routes of the main chain lines are noted.

What do you do during visual survey?

(i) The purposes of the survey should be noted.

This includes (a) is it for pond construction? (b) Is it for damming? (c) Is it for

irrigation purposes; (d) Is it for Hydro-electric power (HEP)?

The purpose will determine the extent of the reconnaissance survey.

(ii) The water parameters to be measured should be noted as from the

beginning.

Such parameters include : (a) Water level; (b) Geological attributes; (c) Soil

conditions (texture, structure and permeability); (d) Water pH, hardness,

alkalinity, chloride, phosphate, ammonia, sulphide, sulphite, dissolved oxygen

etc

DIFFERENCE BETWEEN SURVEYING AND LEVELLING:

Surveying consists in making measurements in the horizontal plane while

Levelling is making measurements in the vertical plane. In surveying, the

measurements consist in fixing position of points in the horizontal plane; 2

points fix a straight line while 3 or more straight lines determine the plan of a

plane figure.
2.7 BOOK KEEPING

Bookkeeping is the recording of financial transactions, and is part of the

process of accounting in business and other organizations. It involves preparing

source documents for all transactions, operations, and other events of a

business. Transactions include purchases, sales, receipts and payments by an

individual person or an organization/corporation. There are several standard

methods of bookkeeping, including the single-entry and double-entry

bookkeeping systems. While these may be viewed as "real" bookkeeping, any

process for recording financial transactions is a bookkeeping process.

OVERALL EFFECTS OF TEMPERATURE IN FISH

Most fish are classified as ectotherms, i.e. their metabolic heat

production, and retaining mechanisms are insufficient to provide body warming.

They are therefore strict temperature conformers and obligate poikilotherms i.e.

the ambient environmental temperature determines their body temperatures. As

a consequence, in fish, temperature sets the rates of virtually all biochemical

reactions and thus the pace of physiological processes. Since temperature has

such a large impact on fish, it is labeled the abiotic ecological master factor.

When uncompensated, metabolic processes increase 2- to 3-fold with a 10°C

increase in environmental temperature, the influence of temperature on

physiological processes being described by the Q 10 temperature coefficient (i.e.

the rate at which a physiological response changes with a 10°C increase in

temperature). However, the magnitude of these changes varies with the

temperatures considered, as Q10 values are not constant for different 10°C

increments and usually decrease at higher temperatures. Consequently,

enzymatic reactions, cellular respiration, oxygen consumption, and thus

metabolic rates vary with temperature.

Since biochemical reaction rates increase with temperature, the standard

metabolic rate (SMR, the metabolic rate required to maintain life and routine

activity) in the ectothermic fish also increases with temperature. The maximum

metabolic rate (MMR or metabolic rate at maximum sustained exercise) on the

other hand, usually has a dome-shaped response to temperature, where it

increases, and subsequently plateaus or decreases. The metabolic (or aerobic)

scope, calculated as the difference between MMR and SMR , is the surplus

energy left after the basal maintenance costs are met and is available for

functions such as digestion, locomotion, growth, and reproduction. Aerobic

scope is used as a proxy for performance.

RECORD KEEPING IN AQUACULTURE

There should be a records of all the activities carried out on the farm from

first day till harvesting time. This will not only help for the coming production

year but will also help to compute farm expenses and income accurately.
Record of pond number and size, fish species cultured, source of fingerlings and

juvenile, date of stocking, number and size of fish stocked, mortality, water

quality data, types of feed used and quantity, sampling record, and fish health

treatment etc.

It is important for the fish manager to keep accurate records of all fish

farm activities. Such records may include labour cost, cost of lime/fertilizer and

rate of application; cost of fingerlings and fish feed; harvest and sales. Fish

farm records aim in good farm management and in evaluating the economic

viability of the project.

 CHAPTER THREE

3.0 FIELD STUDY OF AQUATIC PLANTS

Aquatic plants are plants that have adapted to living

in aquatic environments (saltwater or freshwater). They are also referred to as

hydrophytes or macrophytes to distinguish them from algae and other

macrophytes. A macrophytes is a plant that grows in or near water and is either

emergent, submergent, or floating. Many small aquatic animals use plants such

as duckweed for a home, or for protection from predators. Some other familiar

examples of aquatic plants might include floating heart, water lily, lotus, and

water hyacinth. The term is normally used for plants that grow completely

underwater or with leaves floating on the surface. Parts of the shoot, particularly

flowering stems, will often grow up above the water.

Most aquatic plants live in freshwater in lakes, ponds, reservoirs, canals, or

rivers and streams. Aquatic plants require special adaptations for living

submerged in water, or at the water's surface. The most common adaptation is

the presence of lightweight internal packing cells, aerenchyma, but floating

leaves and finely dissected leaves are also common. Aquatic plants can only

grow in water or in soil that is frequently saturated with water. They are

therefore a common component of wetlands. One of the largest aquatic plants in

the world is the Amazon water lily; one of the smallest is the minute duckweed.

Many small aquatic animals use plants such as duckweed for a home, or for
protection from predators. Some other familiar examples of aquatic plants might

include floating heart, water lily, lotus, and water hyacinth.

3.1 ICHTYOPLANKTON

Ichthyoplankton (from Greek ikhthus, "fish"; and planktos, "drifter") are

the eggs and larvae of fish. They are mostly found in the sunlight zone of the

water column, less than 200 metres deep, which is sometimes called the

epipelagic or photic zone. Ichthyoplankton refers to the planktonic stages of

fish, including eggs and larvae. These early life stages of fish are usually found

in the water column and are an essential part of the marine food chain.

Ichthyoplankton are planktonic, meaning they cannot swim effectively under

their own power, but must drift with the ocean currents. Fish eggs cannot swim

at all, and are unambiguously planktonic. Early stage larvae swim poorly, but

later stage larvae swim better and cease to be planktonic as they grow into

juveniles. Fish larvae are part of the zooplankton that eat smaller plankton,

while fish eggs carry their own food supply. Both eggs and larvae are

themselves eaten by larger animals.

Fish can produce high numbers of eggs which are often released into the open

water column. Fish eggs typically have a diameter of about 1 millimetre (0.039

in). The newly hatched young of oviparous fish are called larvae. They are

usually poorly formed, carry a large yolk sac (for nourishment) and are very

different in appearance from juvenile and adult specimens. The larval period in
oviparous fish is relatively short (usually only several weeks), and larvae

rapidly grow and change appearance and structure (a process termed

metamorphosis) to become juveniles. During this transition larvae must switch

from their yolk sac to feeding on zooplankton prey, a process which depends on

typically inadequate zooplankton density, starving many larvae.

Ichthyoplankton can be a useful indicator of the state and health of an

aquatic ecosystem. For instance, most late stage larvae in Ichthyoplankton have

usually been preyed on, so Ichthyoplankton tends to be dominated by eggs and

early stage larvae. This means that when fish, such as anchovies and sardines,

are spawning, Ichthyoplankton samples can reflect their spawning output and

provide an index of relative population size for the fish. Increases or decreases

in the number of adult fish stocks can be detected more rapidly and sensitively

by monitoring the Ichthyoplankton associated with them, compared to

monitoring the adults themselves. It is also usually easier and more cost

effective to sample trends in egg and larva populations than to sample trends in

adult fish populations.

PLANKTON

Plankton are small, usually microscopic, organisms that drift in the water

column of oceans, seas, and freshwater bodies. They are an essential component

of aquatic ecosystems, serving as a food source for many animals and playing a
critical role in the global carbon cycle. Plankton are the diverse collection of

organisms found in water (or air) that are unable to propel themselves against a

current (or wind). The individual organisms constituting plankton are called

plankters. In the ocean, they provide a crucial source of food to many small and

large aquatic organisms, such as bivalves, fish and whales.

Plankton are primarily divided into broad functional (or trophic level)

groups:

 Phytoplankton (from Greek phyton, or plant), are autotrophic

prokaryotic or eukaryotic algae that live near the water surface where

there is sufficient light to support photosynthesis. Among the more

important groups are the diatoms, cyanobacteria, dinoflagellates and

coccolithophores.

 Zooplankton (from Greek zoon, or animal), are small protozoans or

metazoans (e.g. crustaceans and other animals) that feed on other

plankton. Some of the eggs and larvae of larger nektonic animals, such as

fish, crustaceans, and annelids, are included here.

 Mycoplankton include fungi and fungus-like organisms, which, like

bacterioplankton, are also significant in remineralisation and nutrient

cycling.
  Bacterioplankton include bacteria and archaea, which play an important

role in remineralising organic material down the water column (note that

prokaryotic phytoplankton are also bacterioplankton).

 Virioplankton are viruses. Viruses are more abundant in the plankton

than bacteria and archaea, though much smaller.

IMPORTANCE OF PLANKTONS TO FISH

Zooplankton are the initial prey item for almost all fish larvae as they

switch from their yolk sacs to external feeding. Fish rely on the density and

distribution of zooplankton to match that of new larvae, which can otherwise

starve. Natural factors (e.g., current variations) and man-made factors (e.g. river

dams, ocean acidification, rising temperatures) can strongly affect zooplankton,

which can in turn strongly affect larval survival, and therefore breeding success.

The importance of both phytoplankton and zooplankton is also well-recognized

in extensive and semi-intensive pond fish farming. Plankton population-based

pond management strategies for fish rearing have been practised by traditional

fish farmers for decades, illustrating the importance off

PHYTOPLANKTON

Phytoplankton (/ˌfaɪtoʊˈplæŋktən/) are the autotrophic (self-

feeding) components of the plankton community and a key part of ocean and

freshwater ecosystems. Phytoplankton are microscopic plant-like organisms that

live in aquatic environments, such as oceans, seas, and freshwater bodies. They

are a crucial component of aquatic ecosystems, serving as the primary producers

of organic matter. The name comes from the Greek words φυτόν (phyton),

meaning "plant", and πλαγκτός (planktos), meaning "wanderer" or "drifter".

Phytoplankton obtain their energy through photosynthesis, as do trees and

other plants on land. This means phytoplankton must have light from the sun, so

they live in the well-lit surface layers (euphotic zone) of oceans and lakes. In

comparison with terrestrial plants, phytoplankton are distributed over a larger

surface area, are exposed to less seasonal variation and have markedly faster

turnover rates than trees (days versus decades). As a result, phytoplankton

respond rapidly on a global scale to climate variations.

Phytoplankton form the base of marine and freshwater food webs and are

key players in the global carbon cycle. They account for about half of global

photosynthetic activity and about half of the oxygen production, despite

amounting to only about 1% of the global plant biomass. Phytoplankton are

very diverse, varying from photosynthesising bacteria to plant-like algae to

armour-plated coccolithophores. Important groups of phytoplankton include the

diatoms, cyanobacteria and dinoflagellates, although many other groups are

represented. Most phytoplankton are too small to be individually seen with the

unaided eye. However, when present in high enough numbers, some varieties
may be noticeable as colored patches on the water surface due to the presence of

chlorophyll within their cells and accessory pigments (such as phycobiliproteins

or xanthophylls) in some species.

ZOOPLANKTON

Zooplankton are tiny, usually microscopic, animals that drift in the water

column of oceans, seas, and freshwater bodies. They are an essential component

of aquatic ecosystems, serving as a food source for many animals. Zooplankton

are the animal component of the planktonic community ("zoo" comes from the

Greek word for animal). They are heterotrophic (other-feeding), meaning they

cannot produce their own food and must consume instead other plants or

animals as food. In particular, this means they eat phytoplankton.

Zooplankton are generally larger than phytoplankton, mostly still

microscopic but some can be seen with the naked eye. Many protozoans (single-

celled protists that prey on other microscopic life) are zooplankton, including

zooflagellates, foraminiferans, radiolarians, some dinoflagellates and marine

microanimals. Macroscopic zooplankton include pelagic cnidarians,

ctenophores, molluscs, arthropods and tunicates, as well as planktonic arrow

worms and bristle worms.

Categories of zooplankton
 Zooplankton is a categorization spanning a range of

organism sizes including small protozoans and large metazoans. It includes

holoplanktonic organisms whose complete life cycle lies within the plankton,

as well as meroplanktonic organisms that spend part of their lives in the

plankton before graduating to either the nekton or a sessile, benthic existence.

Although zooplankton are primarily transported by ambient water currents,

many have locomotion, used to avoid predators (as in diel vertical migration)

1.2 EFFECT OF TEMPRATURE ON FISH FEED

Temperature has substantial effect on fish feed. In response to decrease in

water temperature, the enzyme activity of tissues increases. In a stressful and

unfavorable environmental Survival rate in this study were not affected

significantly by different levels of dietary protein but was more affected by

temperature as the groups held at 18 °C had significant (P < 0.05) mortality at

lowest level of dietary protein. On the other hand, mortality at 26 °C water

temperature was not recoded even at the lowest level of dietary protein. The

results are in line with various other finfish and shellfish studies. it was

described that the survival rate of Nile tilapia, Oreochromis niloticus was

significantly lower when it was reared at lower and upper level of its optimum

water temperature.
 Stress resistance of the fish in different life period is affected by levels of

salinity, temperature, environment, and nutrition. The results of present study

showed that resistance rate to thermal stress significantly higher (P < 0.05) in

fish fed dietary protein at 26 °C water temperature who were able to withstand

temperature challenge for longer duration (Table 5) than those fish fed at 18 °C

water temperature which were found to be more prone to temperature challenge

test and exhibited mortality in comparatively less time. Based on the 95%

maximum response of second-degree polynomial regression analyses of PD

g/fish data, it is recommended that fry H. fossilis could perform well if fed with

dietary protein levels between 40.8 and 41.8% with a P/DE ratio of 27.21–27.88

mg protein/kJ DE at 26 °C water temperature. This study also corroborates that

the performance of the fish and protein requirement was strictly governed by the

rearing temperature as fish reared at 18 °C water temperature could not perform

well in terms of growth, feed conversion, and protein deposition even if fed

with the same level of dietary protein.

3.3 EVALUATION OF MAN IMPACT ON AQUATIC ECOSYSTEM

Human activities affect marine life and marine habitats through

overfishing, habitat loss, and the introduction of invasive species, ocean

pollution, ocean acidification and ocean warming. These impact marine

ecosystems and food webs and may result in consequences as yet unrecognized

for the biodiversity and continuation of marine life forms.

 Chemical and industrial pollutant

 Agricultural fertilizers: run off from land have created dead zone in the

ocean where the oxygen is low and therefore the survival of species is low

 Increase in ocean acidity due to high carbon dioxide emission

 Petroleum hydrocarbon: oil spills cause mass mortality of benthos sea fish.

 Sewage and radioactive waste: local power plants and agricultural and

domestic runoff

Global cumulative human impact on the ocean

According to the IPCC (2019), since 1950 "many marine species across

various groups have undergone shifts in geographical range and seasonal

activities in response to ocean warming, sea ice change and biogeochemical

changes, such as oxygen loss, to their habitats." Or The global cumulative

human impact on the ocean refers to the combined effects of various human

activities on the ocean's ecosystems, biodiversity, and overall health.

It has been estimated only 13% of the ocean area remains as wilderness,

mostly in open ocean areas rather than along the coast.

Overfishing
 Overfishing is the removal of too many fish from a fishery, leading to a

decline in the fish population and potentially causing long-term damage to the

ecosystem. Fishing down the food web, overfishing of high trophic fish like tuna

can result in them being replaced by low trophic organisms, like jellyfish.

Overfishing is occurring in one third of world fish stocks, according to a 2018

report by the Food and Agriculture Organization of the United Nations. In

addition, industry observers believe illegal, unreported and unregulated fishing

occurs in most fisheries, and accounts for up to 30% of total catches in some

important fisheries. In a phenomenon called fishing down the food web, the

mean trophic level of world fisheries has declined because of overfishing high

trophic level fish.

Marine pollution

Marine pollution refers to the contamination of the ocean and its

ecosystems by human activities, resulting in harm to marine life, habitats, and

human health. Pathways for this pollution include agricultural runoff into rivers

and wind-blown debris and dust. The Asian brown cloud, a layer of air pollution

that covers much of South Asia and the Indian Ocean for several months every

year, also hangs over the Bay of Bengal. Because of this cloud, satellites

attempting to track ocean acidification and other ocean health indicators in the

Bay have difficulty obtaining accurate measurements.

Toxic Chemicals

Toxic chemicals can adhere to tiny particles which are then taken up by

plankton and benthic animals, most of which are either deposit feeders or filter

feeders. In this way, toxins are concentrated upward within ocean food chains.

Many particles combine chemically in a manner which depletes oxygen, causing

estuaries to become anoxic. Pesticides and toxic metals are similarly

incorporated into marine food webs, harming the biological health of marine

life. Many animal feeds have a high fish meal or fish hydro lysate content. In

this way, marine toxins are transferred back to farmed land animals, and then to

humans.

Phytoplankton concentrations have increased over the last century in

coastal waters, and more recently have declined in the open ocean. Increases in

nutrient runoff from land may explain the increases in coastal phytoplankton,

while warming surface temperatures in the open ocean may have strengthened

stratification in the water column, reducing the flow of nutrients from the deep

that open ocean phytoplankton find useful.

Global Warming

Until recently, ice sheets were viewed as inert components of the carbon cycle

and largely disregarded in global models. Research in the past decade has

transformed this view, demonstrating the existence of uniquely adapted

microbial communities, high rates of biogeochemical/physical weathering in ice

sheets and storage and cycling of organic carbon in excess of 100 billion tonnes,

as well as nutrients. Carbon stores and fluxes in present day ice sheets (2019),

and the predicted impact on carbon dioxide (where data exists).

CONCLUSIONS

The aquatic ecological survey deals with proper planning in both capture

and culture fisheries; planning (survey) in capture fisheries involve the use of a

sophisticated instrument to check the aquatic resources of economic importance

prior to fishing activities, while in the culture fisheries it involves the

appropriate survey of the vegetation, topography, water source, soil type among

others before siting a fish farm. Therefore, before any project is embarked upon,

there is need to survey the land and area where the project is to be done
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