Aquatic Ecosystem

2020-04-29 11:24:43

Aquatic Ecosystem
- 1. Marine Ecosystem
- 2. Fresh Water Ecosystem

They are ecosystem that is surrounded by a body of water. The 2 main types of Ecosystem are Marine and Fresh water.

Aquatic Ecosystems based on salt content have 3 types : ^4b58e5

Fresh Water ecosystem very low 5 ppt.
Marine Ecosys have 35 ppt
Brackish water ecosys contain b/w 5-35 ppt. eg salt marshes, mangrooves swamps.
ocean currently has a pH around 8.0. #important

1. Marine Ecosystem

Aquatic Organisms

Q. Aquatic Organisms that are unattached and live at the air water interface such as floating plants, etc

A. Neuston. Image unavailable in web version: Image

Q. Aquatic organisms which remain attached to stems and leaves of rooted plants or substances emerging above the bottom mud such as sessile algae

A. Periphyton. Image unavailable in web version: Image

Q. This group contains both microscopic plants like algae and animals like crustaceans and protozoans. Not found in moving waters eg

A. Planktons. Image unavailable in web version: Image

Q. This group contains animals which are swimmers. They are large and powerful and can overcome water currents are?

A. Nekton

Benthos are found deep in the botton of water mass

The Factors that limit the productivity of aquatic habitats is :

Photic Zone : extends below to the level where the light level is 1% of that of surface
Aphotic Zone : only respiration takes place here aka profundal zone #important
Dissolved Oxygen : depends on air-water interface and photosynthesis and temperature. O2 is less soluble in warm water. Below 3-5ppm organisms start to dies.
Transparency : affects light penetration. Clay, silt, phytoplankton affect transparency.
Temperature : aquatic animals have narrow temp tolerance limit.

Estuary Ecosystem

![[Estuarine-food-web20160719-7591-1aisej5.jpg |500]]

flow of freshwater from river mixes with salt water from the ocean.
==are the most productive water bodies in the world==

Characterstics

semi enclosed coastal body, has free connection with open sea.
salinity ranges from 0-35ppt, have very little wave action.
receives very high amount of nutrients from fresh and marine water
most heavily populated areas are located here.

Formation

rising sea level
movement of sand and sandbars
glacial processes
tectonic processes
Examples are bays, harbors, lagoons, inlets etc.
salinity and amount of flooding affect life here.
Unique animals like sea lions, sea catfish, saltworts, eelgrass, saltgrasses etc are found here.
India has 14 major river estuaries most of which are located in the east coast.

Issues of Indian Estuarine Ecosystem

Water flow is either in excess or very low.
Modification of estuarine catchment
Pollution, recreation and tourism
Ports and shipping
Urbanization, mining, agriculture
Commercial fishing, over exploitation
submergence of catchment area.

Mangrooves

characteristic littoral plant formation of tropical and subtropical sheltered coastlines
Mangroves are trees and bushes growing below the high water level of spring tides.

Characteristics :

Are evergreen land plants, grow on sheltered shore viz tidal flats, deltas, estuaries, creeks, bays and barrier islands.
adapted to high salinty and anaerobic respiration → through pnuematophores.
Rhizophoras have arching prop roots, while Avicennia have vertical pneumatophores.
exhibit viviparity reproduction ie seeds germinate in the tree itself.
Excess salt is either excreted through leaves or is blocked through roots.
They are located in Sunderbans, Mahanadi, Krishna-Godavari, Cauvery, Goa, Ratnagiri, Maharashtra, Gujarat and Andaman and Nicobar.

Role of Mangrooves

Enhance deposition of sediments in the area
reduce inundation of coastal lowlands
prevents coastal soil erosion
protects from tsunami, hurricanes etc
Enhance natural recycling of nutrients, support flora and fauna, env for breeding, supplies wood etc.

Coral Reefs

living animals and have a symbiotic relationship with ‘zooxanthellae’ microscopic algae which live on corals → assist in nutrient production by providing carbon compounds, also give them colours.
are 2 types hard corals and soft corals. ==Only hard corals build reefs==. ==Polyps are coral reef builders==.
Various shapes associated with them are table like, branched, cups like, boulders etc.
Majority are found in tropical and sub-tropical water but they are also found in deep water in colder regions. Largest cold water reef is Rost Reef of Norway.

Features :

Occur in shallow tropical areas where water is clean, clear and warm.
most productive and complex coastal ecosystems
corals are slow growing zooxanthallae are fast growing.
they help in recycling of scarce nutrients.

Classification

![[Pasted image 20220303070349.png]]

depending on their location they are
- fringing → contiguous to the shore and are most common type eg Andaman
- patch → Ex palk bay, Mannar;
- barrier → parallel to the coastlines separated by lagoons eg Nicobar and
- atoll → circular or semi circular Ex Lakshadweep.
protect against storm surges and erosion, capture nutrients, largest biogenic Calcium carbonate producer, provides substrates to mangrooves, habitat to flora and fauna.

Bleaching :

Occurs when densities of zooxanthellae decline and concentration of photosynthetic pigments within them falls.
usually recovers within a few weeks but if it is prolonged coral host dies.

Causes of Bleaching

Temperature inc and sudden temp drops
Solar irradiance during summer when it is maximum.
Sub aerial Exposure to events like extreme low tides, sea level drops, tectonic uplift
Sedimentation, fresh water dilution, Inorganic nutrients.
Xenobiotics : substances that are foreign to animal life. Ex. during elevations concentrations of Cu, herbicides and oil.
Epizootics : outbreak of disease that affect many animals of the same kind. Ex pathogens that induce bleaching.

Mitigation Measures #important #scheme

To enforce and implement the CRZ and IPZ Notifications MoEFCC has introduced Coastal Zone Management Authorities.
In addition ==Coral reef is included in Schedule I of the Wild Life Protection Act, 1972==.
National Parks, Sanctuaries and Marine Biosphere reserves have been created under the provision of WPA 1972. [[5.3 Environmental Organisations#Wildlife Crime Control Board WCCB 2007 |WCCB]] has also been set up to strengthen law enforcement.
Coastal Ocean Monitoring and Prediction System (COMAPS) : assesses the health of coastal waters.
Land Ocean Interactions in the Coastal Zone (LOICZ) : Investigates the effects of global change on coastal zones.
Integrated Coastal and Marine Area Management (ICMAM) :
Ganga Action Plan and National Ganga River Basin Authority (NGRBA)

Namami Ganga Program #scheme :

Nirmal Dhara : ensuring sustainable municipal sewage management, with Mo Urban Dev and
Nirmal Dhara with Mo Drinking water for rural areas
Aviral Dhara : Enforcing River Regulatory Zones on Ganga Banks
NRI Ganga Fund Clean Ganga Fund :
funds from residents, NRIs/PIO and others, operated through a trust.
Domestic donors will be eligible for tax benefits.

2. Fresh Water Ecosystem

Lentic Ecosystem (Lakes)

Ageing occurs due to accumulation of minerals
Are classified on the basis of salinity as Freshwater, Brackish or Saline lakes.
On the basis of nutrient content as Oligotrophic(low nutrient), Mesotropic(moderate nutrients) and Eutrophic(Highliy nutrient)

Nutrients from lakes can be removed by :

Flushing w/ nutrient low water
Deep water abstraction
On site removal through flocculation/flotation
On site algae removal by filters and P adsorbers.
On site algae skimming.
Artificial mixing/ Destratification
Fish harvesting
Sludge removal

Types of Lakes

Image unavailable in web version: Image

==Lakes have been defined by National Lake Conservation Programme NCLP== as having min depth of 3m and water spread of 10ha having low or very little vegetation. They are less important when compared to wetland.
But ‘Urban Lakes’ has no specific definition

Image unavailable in web version: Image

Harmful Algal Blooms HABs

Algae/ Phytoplankton multiply rapidly resulting in colour change of water, most commonly red or brown
some produce toxins affecting birds, fishes etc
Nutrient enrichment, inc in water temp are causes
similar to [[#^cfb845 |Alagal Blooms]] algal blooms they deplete oxygen
Red tide occurs due to pigment in algae it is a misnomer because blooms are not always red, and not associated w/ tides, are not always harmful.

Eutrophication :

caused by leaching of phosphate and/ or nitrate containing fertilisers from agricultural run offs.
growth of algae called algal bloom - unsustainable and algaes start to die consuming oxygen leaving little for fishes thereby killing them. Algal blooms are of different colour and can be caused due to warm waters ^cfb845
Animals start to feed on this dead algae(detritus) and there is an inc in their population. More O2 is consumed than is created leading to the death of animals.
Anaerobic conditions also produces various toxins.
There are 2 sources of Eutrophication : Point Sources → can be pin pointed and Non Point sources → different sources difficult to regulate.

They can be mitigated by :

Riparian buffers : vegetated area to protect streams from impact of adjacent land use.
Minimise non-point pollution
Nitrogen testing and modelling
Treatment of run off ex N-Testing
Organic farming, integrated farming system
Reduction of livestock densities, improve efficiency of fertiliser
Reduction in N2 emission from vehicles

The nutrient-enrichment of the lakes promotes the growth of algae, aquatic plants and various fauna. This process is known as natural eutrophication.

Similar nutrient enrichment of lakes at an accelerated rate is caused by human activities and the consequent ageing phenomenon is known as ‘cultural eutrophication’.

Wet Land Ecosystem

Ex : lakes/ponds,estuary, lagoon, creek, backwater, bay, coral reef, tidal flat, salt marsh, etc
Are ==areas intermediate in character between deepwater and terrestrial habitats== and are also transitional.
see frequent flooding from deepwater habitats
include lake littorals(marginal areas b/w highest and lowest water level of lakes), flood plains, marshy or swampy area where water gets stagnated
==Depth of wet lands do not exceed 6mts at low tide==
They have adopted plant life and hydric soils

Functions of Wetlands

habitats to flora and fauna
Nutrients recycling
water purification
flood mitigation
maintenance of stream flow
stabilizes the climate, source of livelihood etc.

Mitigation of degradation :

Survey and demarcation
protection of natural regeneration
Artificial regeneration
Removing encroachments

Wetlands in India occupy 18.4% of the country’s area of which 70% is under paddy cultivation.

National Wetlands Conservation Programme (NWCP) #scheme :

was implemented in the year 1985-86
115 wetlands (Annexure) have been identified
Objectives : policy guidelines for conservation, financial assistance, monitor implementation. Central Govt is responsible for overall coordination. State gov resp for management.

Criteria for Identification of National Importance is the Same as that for Ramsar Convention

contains a representative, rare, or unique example of a natural or near-natural wetland type.
supports vulnerable, endangered, or critically endangered species; or threatened ecological communities
supports populations of plant and/or animal species important for maintaining the biological diversity
supports plant and/or animal species at a critical stage in their life cycles, or provides refuge during adverse conditions.
regularly supports 20,000 or more water birds
regularly supports 1% of the individuals in a population of one species or subspecies of water birds
supports a significant proportion of indigenous fish subspecies
important source of food for fishes, spawning ground, nursery etc
important source of food and water resource, increased possibilities for recreation and eco tourism, improved scenic values, educational opportunities.

Montreau Record :

register of wetland sites on the List of Wetlands of International Importance.
highlights those sites where adverse changes in ecological character have occurred or are likely to occur.
employed to identify priority sites for positive national and international conservation attention.
==Chilika lake==, Orissa was placed on the Montreux Record in 1993 due to siltation in the mouth of the lake. It was ==removed in 2002==
==Loktak lake, Manipur== was included on the Montreux Record in 1993 due to habitat degradation.
==Keoladeo NP placed in 1990 for over grazing== and water shortage.

The largest floating treatment Wetland in the country is Neknampur lake of Hyderabad.

Lotic Ecosystem (Rivers)

River ecosystem are flowing waters that drain the landscpae and include biotic and abiotic components.