Environmental biology topic Ecotonebk.pptx

Environmental biology topic ecotone

1. 1

2. 2 An ecotone is a transition area between two ecological communities . Ecotone For example, mangrove forests represent an ecotone between marine and terrestrial ecosystems grasslands  (between forests and deserts) riverbanks, or swamps  or marshland (between dry and wet water) estuaries  (between fresh water and saltwater)

3. 3 Ecocline Ecocline is a zone of gradual but continuous change from one ecosystem to another when there is no sharp boundary between the two in terms of species composition. Ecocline occurs across the environmental gradient It is characterized by gradual change in abiotic factors such as altitude temperature (thermocline), salinity (halocline), depth

4. 4 Edge Effect: Edge effect refers to the changes in population or community structures that occur at the boundary of two habitats ( ecotone ). Or Increased variety and diversity of organisms ( Odum ). Because the area is a transition between two ecosystems or biomes, it is natural that it contains a large variety of species of fauna and flora as the area is influenced by both the bordering ecosystems ( ecotone ). Organisms which primarily or more abundantly present in this zone is called edge species.

5. 5 Characteristics of Ecotone It may be narrow (between grassland and forest) or wide (between forest and desert). It has conditions intermediate to the adjacent ecosystems. Hence it is a zone of tension. A well-developed ecotone contains some organisms which are entirely different from that of the adjoining communities. Ecotones are dynamic, sometimes with strong fluctuations.

6. 6 Estuaries ……. These are areas where both ocean and land contribute to a unique ecosystem Estuary Ecosystem There are a number of estuaries present in Pakistan located along the Indus River that leads up to the Indus Delta. Freshwater from the river flows into these estuaries and merge with saline water from the Arabian Sea. Estuaries of Pakistan

7. 7 Location of Estuaries in Pakistan Pakistan have three major estuaries . One out of three is present along the coastline of Sindh while others are located along with coastal areas of Baluchistan. The estuary in Sindh is known as the Indus estuary that finishes up in the Indus Delta. The Indus delta is present at the inlet of the Indus River. This delta is covering approximately the total coastal area of Sindh primarily south of Karachi.  

8. 8 The two estuaries in Baluchistan are known as Dash and Hingol . Both estuaries are dependent on seasonal variations forming small deltas and have minimal to no vegetation at all.

9. 9 Importance of Estuaries Estuaries have high productivity Estuarine environments are among the most productive on earth, creating more organic matter each year than comparably-sized areas of forest, grassland or agricultural land. Estuaries are Critical Natural Habitats The ecosystem of estuaries supports a diverse variety of biodiversity including animals, aquatic plants, shellfish, fishes, etc. Estuaries are protected water that provides ranges of habitats to many species. The biodiversity includes sea lions, sea turtles, seagrass , pelicans, etc. Estuaries Have Economic Value Estuaries have important commercial value and their resources provide economic benefits for tourism, fisheries and recreational activities. The economy of many coastal areas is based primarily on the natural beauty and bounty of estuaries. When those natural resources are imperiled, so too are the livelihoods of those who live and work in estuarine watersheds.

10. 10 Environmental Degradation of Estuaries There are a number of factors accountable for the environmental degradation of estuaries in Pakistan. These are human activities and natural events. Natural events are floods and sea storms. Human activities that degrade estuaries include urbanization and coastal development. Other factors that are threatening the ecosystem of estuaries include increased level of sedimentation, nutrients flow resulting in algal bloom, climate change, invasive species, pollutants and toxins, wastewater discharges from industrial facilities, etc.