GES1021 – Midterm Study Notes
Lecture 01: Introduction
 Total land area in Singapore: 721.5 km2 (as from Jul 2018)
 Human population: 5.889 million (Jan 2018)
 Population density: 8,274/km2 (Jan 2018)
 In 1819, Singapore was covered by natural habitats, now 95% of forests, 98% mangroves
and 60% of coral reefs have been lost
 Urbanization has caused habitat loss and habitat modification
 New species are still being discovered however, in rich habitats that have escaped
attention (e.g Chek Jawa)
 A new mangrove species was discovered in 2005: Bruguiera hainesii and there has been
a rediscovery of Bruguiera sexangula
 Discovery of Tuas in December 2014
 In Singapore: 2145 native vascular plant species, 25 bat species, 392 bird species, 122
dragonfly species, over 800 spider species, 35 true mangrove plant species, 12 seagrass
species, 255 hard coral species, 50 sea anemone species and 200 sponge species
 Singapore Green Plan (2012): Clean air and Climate change, water, waste management,
public health, conserving nature and international environmental relations
 Introduced species brought into the country for a purpose (e.g guppies to control malaria,
tilapia to supplement protein supply, ornamental plants) or accidentally introduced (giant
African land snail, American cockroach, German cockroach)
 Indigenous/native species are species that are found locally, they are well adapted to local
habitats and there are important keystone species
 Introduced species affect native species (e.g the Changeable lizard Calotes versicolor
displaced the indigenous species Bronchocela cristella)
 Another example is the red ear slider which was released in the wild and competed with
native species for food. They are also very aggressive and carry parasites
Lecture 02: Intertidal Habitats
 Intertidal: between the supralittoral and sublittoral area
 In this habitat, animals and plants are submerged at high tide and exposed at low tide,
they must be able to deal with constantly changing environmental conditions
 Incoming tide: high energy situation, wave action, sand particles sweeping about,
substratum instability, more marine predators
 Outgoing tide: Low energy situation, exposure to UV radiation, dessication, exposure to
wind, lowering of salinity with heavy rainfall, osmotic fluctuation, temperature
fluctuation, terrestrial predators
 Some marine organisms can regulate the concentration of their body fluid so that they are
not affected by change in salinity
 Some can partially regulate their body fluid concentration, while others cannot at all.
 Those species have much more difficulty if they cannot tolerate large changes in salinity
levels
 In 2007 there were mass deaths at Chek Jawa due to monsoons
 In 2010, there was a large oil spill south-east of Changi sea
 Other oil spills occurred in 2012 – 2014
 Other factors that affect intertidal species: Climate change, ocean acidification, rising sea
levels, increase in ocean temperature, plastic waste
 Bleaching events due to rising of the ocean temperature (2016)
 Despite highly stressful conditions, intertidal habitats are rich in biodiversity.
 Why? Abundance of nutrients from land and sea, effective mixing of nutrients, strong
solar energy, high concentration of dissolved oxygen, closer contact between producers
and consumers, diversity of micro-habitats and habitat complexity
Habitats
 Habitat diversity: Mudflat (Sungei Buloh), Seagrass (Chek Jawa), Sandflat (Chek Jawa),
Mangrove (Sungei Buloh/Pasir Ris/Mandai), Reef flat (Chek Jawa), Rocky shore
(Labrador/Check Jawa), Algal Bed (Chek Jawa)
 Habitat complexity: A rocky shore is physically more complex than a sandy shore, the
rocks of different shapes and sizes add complexity
 Zonation adds to the biodiversity: upper intertidal zones vs lower intertidal zones
 Species in upper intertidal zones are last to be submerged but first exposed, while species
in the lower intertidal zones are first to be submerged and last exposed
Intertidal Plants
 Macroalgae, Coralline algae, Padina spp. (Mermaid’s fan seaweed), Sargassum spp.
 Sea grapes (Caulerpa spp.), Coin Seaweeds (Halimeda spp.), Sea lettuce (Ulva spp.)
 Seagrass habitat: only group of flowering plants that are fully submerged in water,
highly specialized, have roots, stems, and leaves unlike algae, stems creep
underground, leaves project above seabed, propagates easily, produce flowers and
fruits with seeds
 They are found in shallow coastal waters, usually on sand flats with a mixture of
mud, extending from mangroves or on coral reef flats. They are best developed in
warm, tropical waters where they form extensive meadows.
 There are 50 species of seagrass worldwide, 20 in southeast Asia and 12 in Singapore
 Seagrass beds: very high productivity, supports high species diversity, leaf blades
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provide extensive surface area that promote growth of epiphytes (non-prasitic plants
that need support), swimming animals move in between the leaf blades seeking
shelter and food, benthic animals crawl about the bottom feeding on rich organic
detritus
Their stems and roots are underground, roots penetrate deep into the substrate, gives
good anchorage and at the same time stabilize the substrate, occurring in extensive
patches they provide refuge and nursery grounds for fish, seahorses, crabs, shrimps
and molluscs
They are a good store of carbon
Seagrass systems support endangered species such as green sea turtle, Olive Ridley,
Wart snake, or Sea Cow (Dugong). The sea cow is fully dependent on sea grass
Intertidal Animals
 They need to protect themselves against harsh conditions
 Prevent themselves from being swept about with the tides
 Prevent themselves from drying out and against solar radiation
 Size of sediment particles: large grain size provides greater space between particles, and
allows better movement of water and dissolved oxygen into deeper layers of the substrate
 Sand anemones – found in sandy habitats
 Barnacles: most common and widely distributed of all intertidal and sometimes subtidal
animals
 Oysters attached to rocks but subjected to predation
 Mud mobsters are a keystone species
 Keystone species are species that have a disproportionately large effect on its
environment relative to its abudance
 Plays a critical role in maintaining the structure of an ecological community, affecting
many other organisms in an ecosystem and helping to determine the types and number of
various other species in the community
 Mudskippers: semi-terrestrial fish that can live above water for extended periods of time
provided they are kept moist, modified pectoral fins are effective for slithering quickly
over the ground, very common in mangroves and mudflats
 Corals, especially those in intertidal habitals contain UV protectants
 Sandcrabs (Scopimera) has a membrane on each leg for exchange of air
 Sand tubeworm: exposed part of tube is made by incorporating small pebbles, all stuck
on by mucus secreted by the worm, provides strength to the exposed tube
 Marine snails: secrete protective calcium carbonate shell throughout life, protective
reflex is to withdraw entire body completely into shell; opening is sealed with a
protective plate carried on the foot of the animal, forms an effective seal
 Examples of marine snails: Tochus (Top shells), Strombus urceus (Black-lipped conch),
cowries, Lambis lambis (Spider conch), Xanthid crabs, Pilumnid crab, Leucosid crabs,
Red Egg crab (Atergatis integerrimus), Velcro crab (Camposia retusa), Fiddler crab,
Brittle stars, Protoreaster nodosus (Knobby sea star), Sea cucumbers
Lecture 03: Subtidal Habitats
 Seafloor or seabed, can be muddy, sandy, or rocky, muddy or sandy seabeds are
referred to as ‘soft bottom habitats’, not easy to study seabed habitats
 Equipment used for shallow water sampling: Smith-McIntyre grab, dredges, sledge.
Submarines and others for deep sea exploration
 Common benthic organisms: Sea fans, sea pens, Noble volute, Sponges, Baler shell,
Basket star
 Benthic organisms, particularly sessile forms and filter feeders are more affected by
sedimentation.
 Importance of seabed benthic habitats: Benthic animals help to condition the bottom
sediment (bioturbation), they make use of accumulated nutrients, contribute to the
marine food chain, many species are exploited for food
 Open sea: three-dimensional environment
 Depth of water column offers wide range of opportunities, fully exploited by marine
organisms
 Three principal lifestyles:
 Drifting (plankton): limited swimming ability, dependent on water currents for
transport
 Swimming (Nekton): strong swimmers (includes most adult fishes, squid, turtles,
prawns and whales), movement between areas independent of currents, Pelagic
species occupy the upper water column, while demersal species stay closer to the
bottom
 Attached (Benthos): bottom-dwelling organisms, generally attached to the substratum
or lifestyle associated with the substratum
 Plants not found on Singapore’s seabed at a depth greater than 7m: sediments, light
penetration, water temperature, water pressure
 Singapore waters: shallow, average 20m depth
 Organisms: Sargassum, Diatoms, Dinoflagellates (Red Tide), Copepods
 Fishes: Rays, Sharks, Bony fishes
 Marine turtles: Loggerhead turtles, Chelonia mydas (Green Sea turtle), Dermochelys
coriacea (Leatherback turtle)
 Also found are sea snakes (Laticauda colubrina), Sousa chinensis (Indo-pacific
Humpbacked Dolphins), Tursiops (Bottlenose Dolphins), Whalebone whale, False
Killer whale, Sperm Whale (Found dead in Jurong in July 2005), Dugong, Jelly
Fishes, Flower crabs, Mosaic reef crabs, Stone fish, Razorfish, Cone shell
 Poisonous (after eating), Venomous (Injection), Traumatogenic (cause physical
injury)
Coral Reefs
 Fringing reefs – extending from land to water
 Patch reefs – associated with a raised seafloor with no connection to land mass
 Main impact on existing reefs is sedimentation, average visibility reduced from 10m in
the 1960s to 2m today. Sedimentation caused by land reclamation
 Of the 197 coral species known from Singapore reefs, two are believed to be locally
extinct (Seriatopora hystrix and Stylophora pistillata)
 Zooxanthellae: Specialized algae that live in a symbiotic relationship with corals. They
photosynthesize and provide nutrition to corals, while the corals provide a home to them
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Hard corals: Branching corals, Boulder corals, Foliose corals, Encrusting coral
There are 255 species of corals, after the bleaching event in 1998 water reached up to 35
degrees C, 90% of corals were bleached and 20% of them failed to recover
Corals are however surprisingly resilient
Intertidal reef flats: only species that can tolerate periodic exposure
Habitat loss: Artificial barriers, risk from toxic chemicals and oil spills, threat from
invasive species. Species loss, climate change
Lecture 04: Primary Vegetation
 Biodiversity: “the variability among living organisms from all sources including, inter
alia, terrestrial, marine, and other aquatic ecosystems and the ecological complexes of
which they are part; this includes diversity within species, between species and of
ecosystems.”
 Biodiversity value: ethical, aesthetic, mental health, economic, potential
 Ethical values: our duties to protect wildlife
 Aesthetic value: organisms are beautiful works of nature; degraded and polluted
environments also have biodiversity but not necessarily what we desire
 Mental health value: researchers have found correlation between nature and better mental
health
 Economic values: what people will pay for a product or service
 Different kinds of economic value: direct value (from harvested items), can be
consumptive (consumed locally, not sold), or productive (consumed locally or
elsewhere, sold)
 Indirect value: non-consumptive, potential
 Non-consumptive Value: Ecosystem services provided by biodiversity which are not
consumed by their use (eg water filtration by the forest surrounding reservoirs, forest
provides space for recreation, landscape for photography, greenery ameliorating heat
island effect in cities, improves human happiness and mental health)
 Potential value: potential to provide an economic benefit to humankind in the future
 Example: Pacific Yew (Taxus brevifolia): not useful, so considered a ‘weed’ tree. Almost
made extinct, however it is a source of paclitaxel for curing different types of cancers
 Genes: can be patented, patent holder controls research and obtain royalties for products
utilizing gene, humans genes highly competitive, conservation for gene preservation
 Habitat: locality, site and particular type of local environment occupied by an organism
 Habitats can be abiotic (non-living) or biotic (living)
 Abiotic environmental components include: latitude, altitude, climate, soil, disturbance
 Biotic environmental components: organism itself, other members of its species, other
species (competitors, parasites, predators, prey, symbionts)
 Vegetation: all the plant life in particular area
 Forest: large area covered by trees
 Tree: usually, large woody plant with a single main stem or trunk
 Singapore habitats: terrestrial (primary, secondary vegetation, waste, and reclaimed land,
coastal vegetation)
 Singapore habitats: Aquatic
 Primary Vegetation: vegetation in which continuity with the primeval vegetation has
never been broken by clearance, vegetation that resembles known primary vegetation of
the same vegetation type, under suitable conditions (very long durations, no disturbance,
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suitable seed sources) a secondary forest may recover to become primary forest
Primary forests in Singapore are now very rare (from 100% to 0.52%) in small isolated
patches
Synusiae: Plant life forms with similar ecological requirements (because of high species
diversity and many microhabitats in primary forests, many life forms have evolved in
tropical rain forests)
Main types of synusiae: autotrophic (green, can photosynthesize) or heterotrophic (nongreen, cannot photosynthesize)
Autotrophic: mechanically independent (erect), mechanically dependent (leaning or
climbing, growing on or into)
Mechanically independent: woody (single trucked or multiple – shrub), non-woody
(herb)
Mechanically dependent plants – growing in water (hydrophyte), growing in air (leaning
or climbing on another plant or support or ground (climber or creeper), growing on
another plant’s stem or branches (epiphyte), growing as epiphyte then sending roots to the
ground (hemi-epiphyte), growing on another plant’s leaves (epiphyll), growing into the
stem of another plant to extract water and mineral nutrients from that plant (hemiparasite)
Hydrophyte: growing in water, supported by water, so very little support tissues and
cannot stand erect outside water
Climber or trailer: weak stems, cannot stand erect, non-woody(herbaceous) or woody,
with support, grows on the support, without support grows on ground
Epiphyll: plant which grows on the leaf of another plant, usually mosses, liverworts or
algae, in very wet habitats, harms the support leaf by blocking off sunlight so reduces
photosynthesis
Hemi-parasite: green-colored, so has chlorophyll for photosynthesis, takes water and
mineral nutrients from host plant
Hemi-epiphyte: half-epiphyte because first grows as epiphyte then sends roots down to
the ground (stranglers – figs)
Saprophyte: Achlorophyllous plant, nutrition obtained from rotting matter, association
with a fungus, Thismia aseroe (now extinct in Singapore), also called a mycoheterotroph
Parasite: Achlorophyllous plant, nutrition obtained from other plants, Rafflesia arnoldii –
largest flower in the world (absent in Singapore)
Canopy stratification: canopy – forest from the ground up
Primary dryland forest has the most (5) strata because of high diversity, complexity of
structure, and great height of the canopy
Secondary forest has 1-2 strata
Temperate forests have fewer strata
Stratum A – Emergent trees, Stratum B – Main canopy, Stratum C – Sub-canopy, Stratum
D – Treelet or shrub layer, Stratum E – forest floor herbs and seedlings
Forest trees, although long-lived die from – Old age, disease, lightning strike, windfall,
damage from falling trees
Dying trees create holes in the canopy
Replenishment and repair of the canopy by new growth of younger trees and seedlings
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Forest growth cycle phases – Gap to building to mature to degenerate
Primary forests in Singapore: dryland forest (192 ha), freshwater swamp (87 ha)
Dryland forest – forest that grows on ground that is not wet most of the year, is usually
what is associated with tropical rain forest, originally covered 82% of Singapore’s land,
now only in Bukit Timah Nature Reserve (20%) and Central Catchment Nature Reserve
(80%)
 Dipterocarp Forest
 Primary forests in Singapore are dominated by meranti family (Dipterocarpaceae), hence
called dipterocarp forest
 Dryland forest plants
 Very high species diversity in plants, animals, and microbes.
 Dominated by trees
 Tree families: Meranti family, Bean family, Chinese olive family, chiku family, mango
family and others
 Freshwater swamp forest: forest that grows on ground that is temporarily too semipermanently inundated by acidic, mineral rich fresh water with water level fluctuations
through periodic drying of soil
 Different from peat swamp forest which has acidic waters
 In Singapore, freshwater swamp forest mostly found in Nee Soon Swamp Forest
 Freshwater swamp forest adaptations: soil waterlogged (less oxygenated) and unstable, so
trees develop adaptations similar to those for mangrove plants
 Prop and stilt roots, kneed breathing roots
 Swamps forest conservation: highest diversity af native freshwater organisms found
nowhere else, 700 species of vascular plants, 48% of freshwater fishes, 71% of
amphibians, 28% of reptiles, 34% of birds, and the entire world’s population of swamp
forest crab
Primary forest animals
 Primeval Singapore had the whole range of forest animals (large mammals like tigers,
elephants, deer, tapir etc…)
 Most of the large animals now extinct, top predator is now the reticulated python
 Small mammals: banded leaf monkey, cream colored giant squirrel, Malayan colugo
(Flying lemur)
 Long-tailed macaque, pest, raids homes, attack people and carry Herpes B virus, they
also do not fulfill ecological function as seed dispersers because humans feed them.
Economic Value of Primary Forests
 Direct values: produce wood for timber, fruits, wild game
 Indirect Value: Aesthetics, recreation, education, amelioration of micro-climatic effects
(Rain, cooling down), maintenance of water quality, genetic resources for patents, removal
of carbon from atmosphere, source of ornamental plants
Protection of Primary Forests:
 Study organisms and ecosystems
 Manage areas to support pollinators and dispersers
 Propagate forest plants
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Re-introduce dispersers
Keystone species to be given special protection
Surveillance and enforcement against poaching and vandalism
Minimize impact of construction works
Avoid introducing exotic species
Lightning protection
Forbid smoking
Lecture 05 – Singapore Biodiversity
 Why do we need to conserve biodiversity? – loss of species leads to a disruption of
ecosystem processes, biodiversity takes millions of years to evolve, species provide a rice
genetic bank of bioactive substances, species simply have the right to exist
 Species loss is permanent. There is an estimated 3-100 million species present on earth
 1.4 – 1.8 million identified
 Based on the extinction rate of 1% per annum, the planet will lose 20% of its biodiversity
by 2030.
Components of the environment
 Atmosphere (air) – Shields earth from UV radiation, moderates temperature, lifesupport gases
 Hydrosphere (water) – moderates climate – absorbes/releases heat, contributes
moisture to atmosphere and lithosphere, contributes essential elements/compounds
 Biosphere (life) – plants convert solar/chemical energy to organic matter, facilitate
cycling of materials, environmental cleansing, physical environment modification
 Lithosphere (soil) – contributes essential elements/compounds
Living vs. Dead Systems
 Biodiversity helps with life support
 Ecosystems are resource systems – provide goods and services
 Biodiversity also referred to as the “natural capital”
 Important to maintain healthy ecosystems in order to enjoy the goods and services
 Forest ecosystem provides goods (timber, fuel wood, pulp, leaves, roots, fruits, traditional
medicine) and services (retard soil erosion, regulate climate, regulate water cycle, energy
flow and chemical cycling, carbon fixing, purify air and water, provide habitat to
numerous species)
 Animals may be noxious and pests, dangerous, poisonous, or venomous and some are
carriers of human infectious diseases
 Singapore national flower: Vanda Miss Joaquim
 Seagrass ecosystem: goods (food, medicine, fertilizer/fodder, paper) and services (binds
sediment, reduced turbidity, retards erosion, pollution filter, nursey, support large
invertebrate stocks, critical habitat of dugings, food for green turtles and young
hawksbills
 Biodiversity provides food, medical and pharmaceuticals, construction materials,
physical environment protection, balanaced cycling of materials, eco-tourism, carbon
fixation, soil enrichment, storage and purification of water, filtration, and detoxification of
pollutants and waste products
 Physical environment protection: e.g mangroves
 Mangrove roots prevents mud and sand from being washed away with tide and river
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currents, also slowly regenerate the soil by penetrating and aerating it and reduce damage
from violent storms
Balanced cycling of materials: e.g mud lobsters
They excavate below the surface of the mud, pushing mud to the surface and making its
home higher as it digs, in this way helping bring nutrients from deep underground to the
surface, helping in the recycling of nutrients in the ecosystem