Transcript PRODUCTION IN INLAND AND MARINE WATERS IKENWEIWE Bolatito Nafisat (PhD) ,

PRODUCTION IN INLAND AND MARINE WATERS
IKENWEIWE Bolatito Nafisat (PhD)
DEPARTMENT OF AQUACULTURE AND FISHERIES
MANAGEMENT
UNIVERSITY OF AGRICULTURE, ABEOKUTA
[email protected], 08033770265
Production in inland and Marine
Waters
FIS 702
(2 Units) Elective
Course outline
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Types of aquatic ecosystem,
Limiting factors controlling fish production.
Allochthonous and autochthonous
migration and
Resource distribution
INTRODUCTION
• The current overall fish production is estimated at
500.000 metric tones, whereas the requirement
or demand for fish production is about 5 million
metric tones (Dada 2004).
• This clearly shows that there exist a wide gap
between fish production and demand for fish
products.
• Fish production can only be increased when the
spatially variable production factors controlling
aquaculture and inland fisheries are well
understood and properly addressed.
CONCEPT OF ECOSYSTEM
• An ecosystem is defined as “a spatially explicit
unit of earth that includes all of the
organisms, along with all the components of
the abiotic environment within its
boundaries” (Likens, 1992).
• An Ecosystem is a combination of two words
"Ecological" and " system“.
• An ecosystem is a biological
environment consisting of all the
organisms living in a particular area, as
well as all the nonliving, physical
components of the environment with
which the organisms interact, such as
air, soil, water and sunlight
Types of ecosystem
• There are two broad classification of
ecosystem:
– Natural and
– Artificial
A. Natural ecosystem
It is classified into two parts
1) Terrestrial ecosystem
• Few examples are:
* Forest Ecosystem
* Sahara Desert Ecosystem
* A Grassland Ecosystem
* A Semi-forest Ecosystem
* An ecosystem on a snow field
* A Scrubland ecosystem
* A Cold desert ecosystem
* Wetland ecosystem
* Wild Life Sanctuaries, National Parks, Animal
Reserves
2) Aquatic ecosystem (to be discuss later)
B. Artificial ecosystem
• Artificial ecosystems are created by humans.
• Examples include
– animal reserve or a giant terrarium e.g. zoo
– Gardens are also artificial ecosystem
– Crop lands like maize, sugarcane, rice-fields,
wheat, orchards,
– dams, aquarium, cities, and manned spaceship.
• The basic biotic and abiotic components are
defined by man in artificial ecosystem.
TYPES OF AQUATIC ECOSYSTEM
Aquatic ecosystem is divided into two partsMarine ecosystem and freshwater ecosystem.
Marine
• Marine ecosystems cover approximately 71%
of the Earth's surface and contain
approximately 97% of the planet's water. They
generate 32% of the world's net primary
production.
• Marine ecosystems can be divided into the
following zones:
– oceanic (the open part of the ocean where
animals such as whales, sharks, and tuna live);
– profundal (bottom or deep water);
– benthic (bottom substrates);
– intertidal (the area between high and low tides);
– estuaries;
– salt marshes;
– coral reefs; and
– hydrothermal vents (where chemosyntheticsulfur
bacteria form the food base).
• Classes of organisms found in marine ecosystems
include
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brown algae,
dinoflagellates,
corals,
cephalopods,
echinoderms, and
sharks.
• Fish caught in marine ecosystems are the biggest
source of commercial foods obtained from wild
populations.
• Environmental problems concerning
marine ecosystems include unsustainable
exploitation of marine resources (for
example overfishing of certain species),
marine pollution, climate change, and
building on coastal areas.
Freshwater
• Freshwater ecosystems cover 0.80% of the
Earth's surface and inhabit 0.009% of its total
water. They generate nearly 3% of its net
primary production. Freshwater ecosystems
contain 41% of the world's known fish species.
• There are three basic types of freshwater
ecosystems:
• Lentic: slow-moving water, including pools,
ponds, and lakes.
• Lotic: rapidly-moving water, for example
streams and rivers.
• Wetlands: areas where the soil is saturated or
inundated for at least part of the time
Lake ecosystems
• Lake ecosystems can be divided into zones:
– pelagic (open offshore waters);
– profundal;
– littoral (nearshore shallow waters); and
– riparian (the area of land bordering a body of
water).
• Two important subclasses of lakes are ponds,
which typically are small lakes and water
reservoirs.
Abiotic characteristics
• Abiotic environmental factors of aquatic
ecosystems include temperature, salinity, and
flow.
• 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.
Biotic characteristics
• The organisms (also called biota) found in aquatic
ecosystems are either autotrophic or heterotrophic.
• Autotrophic organisms
– Autotrophic organisms are producers that generate organic
compounds from inorganic material.
– Algae use solar energy to generate biomass from carbon
dioxide and are the most important autotrophic organisms
in aquatic environments.
– Chemosynthetic bacteria are found in benthic marine
ecosystems. These organisms are able to feed on hydrogen
sulfide in water that comes from volcanic vents.
• Heterotrophic organisms
– Heterotrophic organisms consume autotrophic
organisms and use the organic compounds in their
bodies as energy sources and as raw materials to
create their own biomass.
– Euryhaline organisms are salt tolerant and can
survive in marine ecosystems, while
– stenohaline or salt intolerant species can only live
in freshwater environments.
Other forms of Aquatic ecosystem
– lake
– ocean
– creek
– lagoon
– bog
– sea
– glacier
– tidal pool
– geyser
– fen
– flood plain
– bog
– estuary
– aquifer
– salt lake
• Marsh - shallow water with non-woody plants
growing above water level
• Swamp - like a marsh but with bushes and trees
growing from the water as well
• Pond - a small and shallow body of water with plants
growing above water level only on the edges;
• River - a moving body of water that flows from one
place to another.
• Stream - smaller than a river,
• Puddles - body of water that lasts for a few days
• Spring - area where underground water is discharged
onto the land surface forming a pond or stream
LIMITING FACTORS CONTROLLING
FISH PRODUCTION
• Fish production is dependent on a number of
factors: these factors have been termed
production factors because fish yield/output
is' a function of various combinations of
parameters or factors.
• The factors fall under environmental, physical,
economic, and social factors and all these will
show spatial variability within and between
given areas or zones.
Attempt is made here to identify some
production functions controlling aquaculture
and inland fisheries based on FAO 1991 are:
– Land availability
– Capital ownership
– Topography
– Climate
– Season and area
– Water availability
– Water quality
– Potential for competitive water use
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Soil properties
Predators
Adjacent land uses
Proximity to supporting infrastructure
Access roads
Local political, social & economic factors
Environmental constraints
Security
Availability of skilled manpower
Exploitation method
Pollution
Aquatic macrophytes
Communication, Etc
• The greatest threat to the maintenance of
ecological integrity is habitat destruction
(Biodiversity Working Party 1991).
• Such changes could include serious pollution
of sediments, reduction in stream flow by
river regulation, removal of habitat (desnagging, draining wetlands) or significant
changes in catchment land use, any of which
could cause significant ecosystem
deterioration.
Further Readings
• Beverton, R.J.H. 1984. Dynamics of single species.
p.13-58, in: R.M. May (ed). Exploitation of Marine
Communities. Berlin: Springer Verlag.
• Beverton, R.J.H. 1990. Small marine pelagic fish
and the threat of fishing; are they endangered?
Journal of Fish Biology, 37(Supplement A): 5-16.
• Christensen, V. 2000. Indicators for marine
ecosystems affected by fisheries. Marine and
Freshwater Research, 51: 447-450.