EVSC30006 Lecture Notes - Lecture 10: Eutrophication, Species Richness, Thermophile
1 Jun 2018
School
Department
Course
Professor
LECTURE 10: EFFECTS OF URBANISATION ON PONDS
• Urbanisation is a main driver of wetland & natural pond destruction – drastic reduction in abundance of ponds
• Density of ponds can sometimes be higher in cities than natural areas – create for parks, gardens, storm water
URBAN PONDS
• Features: designed to trap pollutants & sediments, protect against flooding, irrigation, water reserve & habitat
• Have different functions and design from rural ponds:
o Smaller and shallower
o Younger, constructed environment
o Isolated & poor connectivity
o Low water quality & exotic organisms
• Habitat destructions, fragmentation & obstacles to biodiversity impair ponds at the landscape scale in urban areas
• Changes to water physio-chemistry: warming, eutrophication, pollution
• Physical disturbances: hydrological (permanent to temporary ponds), light (photosynthesis) & noise regimes altered
• Habitat transformation and management has led to decreased habitat diversity – need to maintain when cleaning
• Ecological Traps: habitat attractive to native species, but contaminated with presence of exotic predators
o Pond becomes trap for animals that cannot assess habitat quality
Dispersal
Active Aerial
Active Terrestrial
Passive Aerial
Passive Terrestrial
Example
Dragonflies,
most insects
Amphibian,
Freshwater turtle
Plants (seeds)
Snails
Transport
Flying
Locomotion
Wind
Attaches to mammals
or birds
Water Quality
• Lower quality than rural systems overall, sometimes can be better quality
• Stormwater run-off including pollutants: nutrients, heavy metals, suspended solids
• Frogs: heavy metal pollution contributing to global declines
o Endocrine disrupting chemical conduct to male feminisation in frogs, also case for fishes in stream
• Eutrophication: too many nutrients, making pond too productive, water coloured and turbid due to phytoplankton
(cyanobacteria) = low biodiversity
o Due to run-off with lots of nutrients, inputs through leaf litter (wind and rain), and input through humans
(feeding species - nutrients accumulate)
Biodiversity
• Low species richness compared to rural
• Frog species richness is lower with increasing urbanisation
• Macro-invertebrates decreasing most, followed by amphibians, then fish
• Favoured by generalists, pollution resistants, thermophilous, disperse by air, exotic
• Threatened species can colonise cities
• Specie traits: temperature and body size - small body size dominate urbanised ponds, increasing thermal tolerance
need in more urban areas
Pond: a man-made or natural waterbody between 1m2 and 2ha in area, with a maximum depth of 8m
Document Summary
Urban ponds: have different functions and design from rural ponds: Features: designed to trap pollutants & sediments, protect against flooding, irrigation, water reserve & habitat. Low water quality & exotic organisms: habitat destructions, fragmentation & obstacles to biodiversity impair ponds at the landscape scale in urban areas, changes to water physio-chemistry: warming, eutrophication, pollution. Physical disturbances: hydrological (permanent to temporary ponds), light (photosynthesis) & noise regimes altered: habitat transformation and management has led to decreased habitat diversity need to maintain when cleaning. Ecological traps: habitat attractive to native species, but contaminated with presence of exotic predators: pond becomes trap for animals that cannot assess habitat quality. Lower quality than rural systems overall, sometimes can be better quality. Stormwater run-off including pollutants: nutrients, heavy metals, suspended solids. Frogs: heavy metal pollution contributing to global declines: endocrine disrupting chemical conduct to male feminisation in frogs, also case for fishes in stream. Frog species richness is lower with increasing urbanisation.
