Aquatic Food Production Systems

benthic

bottom of the seabed

pelagic

mid water column

density dependent factors

• biotic

• depend on the size of the population

• food availability, competition

density independent factors

• abiotic

• not dependent on the size of the population, but will impact it

• water temperature, pH

definition of aquaculture

cultivation of aquatic organisms in controlled environments like ponds, tanks, or ocean enclosures

description of demersal trawling

• deep sea

• high catch effectiveness

• high energy impacts

• low selectivity

• seabed damage

impact of aquaculture on habitat loss

• conversion of natural habitats into fish farms

  • cleared & modified

• affects ecosystems & local communities

impact of aquaculture on pollution

• excess nutrients from waste & uneaten feed leaches into surrounding water bodies

• causes eutrophication, algal blooms, and anoxia

• antifouling agents (preventing the growth of marine organisms) are biocides

• antibiotics could lead to antibiotic resistance

impact of aquaculture on spread of disease

• high stocking density = rapid spread of disease

• lack of biosecurity can spread disease to wild fish populations

impact of aquaculture: escaped species

• outcompete wild population

• interbreeding = transmission of genetic diseases

• genetically modified fish

impact of aquaculture on ethical issues & biorights

• conflict with rights & interests of indigenous communities

• establishment of facilities on traditional fishing grounds

• impact cultural heritage

impact of aquaculture on rights of indigenous cultures

• conflict with rights & interests of indigenous communities

• establishment of facilities on traditional fishing grounds

• impact cultural heritage

desirable factors for GM of fish

• taste

• range of tolerance (temperature/disease/saline)

• texture

• bright colour

• carnivorous = higher energy inputs

goods provided by mangroves

• wood for construction/fuel

• nursery for fish/crabs/shellfish

• provide fruit

• provide $20k/ha/year

services provided by mangroves

• hold sediment

• reduce soil erosion

• nurseries = shelters from predators

• ecotourism

• sequester CO2 in troposphere = temperature regulation

• high biodiversity = high resilience

description of mangroves

• ecotone

• roots in intertidal zone (exposed to high/low tide)

• shallow, brackish, warm water

• found in tropical regions

• complex food chains

Impacts of escapee GMOs

• may outcompete other species

• may predate other species

• carry disease to other species

• breed with wild stock

  • fast growth = high inputs unavailable naturally

  • bright coloured individuals at higher risk of predation

  • gene pool contamination

• e.g. signal crayfish