EVSC30006 Lecture Notes - Lecture 11: Estuaries And Coasts, Marine Debris, Habitat Fragmentation
1 Jun 2018
School
Department
Course
Professor
LECTURE 11: URBANISATION & MARINE ENVIRONMENTS
• Development of agriculture has led to decreasing trends in all species due to increasing nitrogen, phosphorous,
sediment, PP, eutrophic plankton & invasive species
• Main drivers of loss: exploitation, habitat loss, pollution, disturbance (in that order of severity)
IMPACT OF MARINE URBANISATION
Impact
Description
Exploitation:
Fisheries
• Urbanisation increases access of fishers to estuaries & coasts
• People in cities consume more fish than in rural areas, spend more income on food & eat out
more frequently
Sydney Harbour
• Historical use of industry, high levels of pollution run-off, commercial fishing banned 2006
• Guidelines for recreational fishing
• 70% of fishers rate quality of fishery as good & ignore regulation, less fishing in restricted areas
Oysters
• 85% oyster reefs lost globally, around highly populated areas
• Port Phillip Bay: direct harvest of oysters, indirect effects of scallop dredging – 100 years of
harvesting, then dredged
• Ecosystem services: maintenance of wildlife, raw material/food, fisheries provision, water
purification
Invasive
Species
• Urban areas high in invasive species: ballast water, hull, & introduction (accidental & deliberate)
• Urban areas can promote the secondary spread of invasive species – altered biotic and
environmental conditions
• Northern Pacific Sea Star: in P.P Bay, first recorded 1995, prolific breeders & fierce predators
Contamination
• Heavy metal and chemicals due to direct dumping and through drains, due to impervious
surfaces
• Elevated nutrients & turbidity: eutrophication – algal blooms
• Rise of turfs: disturbed kelp forests results in small turfing algae where no kelp can recolonise –
urban areas provide feedback loop which aids algae
• Marine Debris: plastics and microplastics higher in urban areas
Habitat
Modification
• Urbanisation, growing populations, in biodiversity hotspots & coastal zone, in areas of low
economic & human capacity = exacerbation of the problem
• Mangroves: 65% lost since 1900’s due to aquaculture & developments – habitat fragmentation &
loss
• Proliferation of artificial structures: marinas, oil platforms, canal living, wind turbines in oceans,
especially coastal defence (sea walls, breakwaters)
• Introduce novel habitats: vertical, flat & featureless – good for exotic species
• Reduce natural habitats, support low native biodiversity, habitat for exotic species
Document Summary
Fisheries: urbanisation increases access of fishers to estuaries & coasts. People in cities consume more fish than in rural areas, spend more income on food & eat out more frequently. Sydney harbour: historical use of industry, high levels of pollution run-off, commercial fishing banned 2006, guidelines for recreational fishing. 70% of fishers rate quality of fishery as good & ignore regulation, less fishing in restricted areas. 85% oyster reefs lost globally, around highly populated areas. Port phillip bay: direct harvest of oysters, indirect effects of scallop dredging 100 years of harvesting, then dredged. Ecosystem services: maintenance of wildlife, raw material/food, fisheries provision, water purification. Species: urban areas high in invasive species: ballast water, hull, & introduction (accidental & deliberate, urban areas can promote the secondary spread of invasive species altered biotic and environmental conditions.
