AQUATIC science and wetland management


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BONGA UNIVERSITY
College of Natural and Computational Science
Department of Biology
MODULE TITLE: FISHERIES AND AQUATIC SCIENCES COURSE TITLE: AQUATIC SCIENCE AND WETLAND
MANAGEMENT (BIOL3091)
PREPARED BY: - 1.ASRAT AERO (MSC) 2. MELAKU
EDITED BY: - HUSNIA ABDULKERIM (MSC)

Table of Contents
CHAPTER ONE .......................................................................................................................3 1.1. Definitions and Global Proportions ...................................................................................4 1.2. Inland Aquatic Ecosystems ...............................................................................................8 1.2.1. Lentic Freshwater Ecosystems ....................................................................................8 1.2.2. Lotic Freshwater Ecosystems ...................................................................................11 1.3. Marine Ecosystems .........................................................................................................13 1.4 Estuarine Ecosystems.......................................................................................................14 1.5 Wetland Ecosystems ........................................................................................................14
CHAPTER TWO ....................................................................................................................17 2. Major Freshwater Bodies and Wetlands of Ethiopia ..............................................................17
2.1. Catchments/Drainage Basins...........................................................................................17 2.2. Drainage Basins of Ethiopia............................................................................................20
2.2.1. The Ethiopian Drainage Systems ..............................................................................20 2.2.2. Lakes........................................................................................................................22 2.2.3. Rivers.......................................................................................................................23 2.2.4. Wetlands ..................................................................................................................26 CHAPTER THREE ................................................................................................................30 3. Ecology of Aquatic Ecosystems ............................................................................................30 3.1. Zonation‟s in Aquatic Ecosystems ..................................................................................30 3.1.1. Zonations in Freshwater Ecosystems ........................................................................30 3.1.2. Zonations in Marine Ecosystems ..............................................................................32 3.2. Autochotonus and Allochtonous Inputs...........................................................................36 3.3. Community Structure......................................................................................................36 3.3.1. Plankton community.................................................................................................37 3.3.2. Nekton and Benthic communities .............................................................................43 3.4. Aquatic Ecology .............................................................................................................44 3.4.1. Abiotic Components.................................................................................................44 3.4.2. Functional Feeding Groups.......................................................................................44 CHAPTER FOUR...................................................................................................................47 4. Water Pollution .....................................................................................................................47 4.1. What is Water Pollution? ................................................................................................47

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4.2. Sources of Water Pollution .............................................................................................48 4.3. Types of Water Pollutions and the Contaminants ............................................................49 4.4. Forests and Water Quality...............................................................................................56 CHAPTER FIVE.....................................................................................................................60 5. Water Quality Assessment .................................................................................................60 5.1. Water Quality .................................................................................................................60 5.2. Water Quality Assessment Parameters ............................................................................61
5.2.1. Physico-chemical Parameters ...................................................................................63 5.2.2. Biological Parameters ..................................................................................................69
5.2.3. Sampling of Surface Waters .....................................................................................74 CHAPTER SIX .......................................................................................................................79 6. Aquatic Resources .............................................................................................................79
6.1. Fish and Fisheries ...........................................................................................................79 6.2. The Ethiopian Fish and Fisheries ....................................................................................90
6.2.1. The Classification of Ethiopian Fish .........................................................................90 6.2.2. The Ethiopian Fisheries ............................................................................................93 CHAPTER SEVEN .................................................................................................................97 7. Water Basin Management and Monitoring .........................................................................97 7.1. Basic Water Management and Monitoring Programs.......................................................97 7.2. The Nile Basin Initiative (NBI) .......................................................................................98 7.3. The Water Framework Directive ...................................................................................102 7.4. Convention on Wetlands Management ..........................................................................103 REFERENCES ...................................................................................................................... 106 APPENDIX-1 ........................................................................................................................107 APPENDIX 2.........................................................................................................................110 APPENDIX-3 ........................................................................................................................113 APPENDIX-4 ........................................................................................................................114 APPENDIX-5 ........................................................................................................................115

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CHAPTER ONE
1. Introduction to Aquatic and Wetland Ecosystems
Chapter Objectives:
At the end of this chapter you will be able to:
 Distinguish between wetlands and uplands using soils, hydrological and vegetation criteria
 Describe the various ecosystem functions that are provided by wetlands  Evaluate the economic value of ecological services provided by wetlands  Define an aquatic ecosystem  Distinguish between the freshwater, marine and estuarine ecosystems  Describe the freshwater, marine and estuarine ecosystems  Distinguish between the lentic and lotic inland aquatic ecosystems  Describe the wetland ecosystems  Explain the global and relative proportions of aquatic ecosystems.

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This photograph of the Salmon River Estuary on the central Oregon coast illustrates the beauty and interconnectedness of a tidal wetland. Above - and below – surface runoff flows from the forested upland in the background through the wetland in the center of the photo and ultimately into the estuary.
1.1. Definitions and Global Proportions Activity:
 Dear student, from your ecology course can you remember about ecosystem? What is an ecosystem? What are the two major categories of world ecosystems?
Dear student let us now proceed on defining one of the two major ecosystem categories: i.e. Aquatic ecosystem. These are ecosystems that occupy the largest part of the biosphere and are covered with water. There are two major categories of aquatic biomes.

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Fresh water ecosystems: with salt concentration of < 3 gm/l or 3 parts per thousand (ppt.).
 These inland water bodies are closely linked to soils and biotic components of terrestrial biomes through which they pass and are influenced by patterns and speed of water flow and climate of area in which it‟s located.
There are two categories of freshwater ecosystems:  Standing (lentic) bodies of water which include lakes, ponds and inland wetlands; and  Moving (lotic) bodies of water which include rivers and streams.

A. Lakes are large, natural bodies of standing water which could be fresh or saline. Lakes are formed when precipitation, runoff, groundwater seepage fills depressions in earth‟s surface. These depressions can be formed by:-

 glaciation (Great Lakes, NA)  tectonic or crustal displacement (Lake Victoria, East Africa; Lake Baikal,
Russia; Rift valley lakes)  volcanic activity (Bishoftu crater lakes)

Lakes could have different shapes (morphometry) depending on how they were formed and how geological processes have modified them. Large lakes may have many characteristics similar to oceans, such as a large pelagial (open water) region, deep depth, an extensive bottom area (benthic region), etc.

This is a water ecosystem that provides many vital environmental functions both to human being and other organisms. For example:

They are important in nutrient recycling, flood attenuation and habitat provision to wildlife (biodiversity) The largest proportion of rainfall comes from evaporation of water bodies They are also used for human recreation, and are very important to the tourism industry, especially in coastal regions

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Activity:  As it is a case with any type of ecosystem, what are the two major factors or components of aquatic ecosystems? Write down before you pass on to read the following sections.
Aquatic ecosystems are composed of biotic communities (also called biota) and a biotic environmental factor, which form a self-regulating and self-sustaining unit. The biotic components of aquatic ecosystems are either autotrophic or heterotrophic as it described in chapter 3. Activity:
 What is the difference between autotrophic and heterotrophic organisms in aquatic habitats? Give examples
Abiotic environmental factors of aquatic ecosystems include the amount of dissolved oxygen (DO), temperature, amount of light, salinity, pH, nutrients such as nitrogen (in the form of mainly nitrates) and phosphorus (in the form of phosphates). For more information on the abiotic components of aquatic ecosystem refer to section 5.2.1. of chapter 5.
The amount of dissolved oxygen in a water body is frequently the key substance in determining the extent and kinds of organic life in the water body. Fish need dissolved oxygen to survive. Conversely, oxygen is fatal to many kinds of anaerobic bacteria. The salinity of the water body is also a determining factor in the kinds of species found in the water body. Organisms in marine ecosystems tolerate salinity, while many freshwater organisms are in tolerant of salt. Freshwater used for irrigation purposes often absorb levels of salt that are harmful to freshwater organisms.
Activity:  Aquatic ecosystems can be broadly categorized in to three. What do you call them? What are the major differences that lie among the three?

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 There are three major types of aquatic ecosystems:  Inland (mainly freshwater) Ecosystems  Marine Ecosystems  Estuarine Ecosystems
The inland aquatic ecosystems include lakes, rivers and streams that have negligible salinity (salt content) of a little greater than or equal to 10 grams of salt per 1 liter of water. The waters of inland aquatic ecosystems are said to be largely freshwater with an exception of a few salty lakes.
Activity:  In Ethiopia can you give examples of salty lake? Name it
The marine ecosystems include seas and oceans and are characterized by high salinity reaching 370 gram of salt per liter of water. All marine waters are salty. The estuarine ecosystems are areas formed at the junction of the freshwater and marine waters.
Activity:  How do you compare the salt content of estuarine waters to that of freshwaters and marine waters? Explain
The largest proportion, about 75%, of the Earth‟s surface is covered by water. Marine ecosystems cover approximately 71% of the Earth's surface and constitute about 97% of the planet's water. The inland aquatic ecosystems, in contrast, account only for smaller proportion covering about 0.8 % of the Earth's surface and constituting 3% of its total water. About 68.7% of this is either frozen in glaciers and ice and 30.1% is buried in aquifers as groundwater. The remainder is found as surface waters (in lakes, ponds, rivers, and streams) and as moisture. Lakes constitute the largest proportion (87%) of the surface waters.

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Figure 1.1. Distribution of Earth‟s Water
1.2. Inland Aquatic Ecosystems These refer to the bodies of water that are totally land locked and include freshwater ecosystems typically the lakes and rivers characterized by having low salinity of about 0.1 % or 1 ‰ (i.e.1 gram of salt per 1kg or 1 L of water).The inland water bodies are closely linked to the terrestrial biomes that surround them or through which they flow. Overall characteristics of freshwater ecosystems are influenced by the pattern and speed of water flow, and the local climate.
The freshwater ecosystems generate nearly 3 % of net primary production and contain 41% of the world's known fish species. Three basic types of inland aquatic ecosystems can be recognized. These are lentic, lotic and wetland ecosystems.
Lentic freshwater ecosystems are standing freshwater ecosystems such as lakes and ponds Lotic freshwater ecosystems are the rapidly moving freshwater ecosystems such as rivers and streams
1.2.1. Lentic Freshwater Ecosystems Lakes and deeper ponds exhibit temperature stratification known as thermal stratification during the summer (warmer) and winter seasons in temperate zones.

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Activity  What is thermal stratification of lakes and deeper ponds? How is it formed?  What factors cause the creation of thermal stratification?
However, the effect of thermal stratification is more pronounced during summer season when still air condition is more prevalent. Sunlight heats the upper layers of water as far as it penetrates and the deeper water remains cold. Consequently, the warmer upper water (known as epilimnion) becomes separated from the lower colder water (known as hypolimion). A narrow zone of water that separates between the warmer and colder waters undergoes a rapid or exponential temperature change and it is known as thermocline (See Fig. 1.2. below)

Activity:  How do you compare the density of epilimnion and hypolimnion?  Why does epilimnion float? Why does hypolimnion lie beneath?

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AQUATIC science and wetland management