SIT final
Describe the life history differences between colonial organisms (such as corals) and solitary organisms (such as us or fish)
Solitary Fixed morphology Finited size Age dependent mortality Limited reproductive potential Colonial Flexible Indefinited Size dependent Increases with size
When you think about the coral trout case study, describe the many potential effects climate change may have on corals and what you would study to answer this question?
Climate change is a major cause of reef degradation It increasing sea surfact temperature (SST) and ocean acidification Carbon dioxide emissions are tracking upwards Increasing temperature Coral bleaching Change in species distributions Ocean acidification Affects calcifying organism (corals, crustaceans, mulluscs) Changes in behavior Global extent of bleaching in 2015/2016 Severe, > 30% of corals affected 2016: entire Northern end of GBR was severely bleached Extreme bleaching effects almost all taxa To look at the effects of climate change on corals I would replicate an experiment that Vanessa talked about Volcanic CO2 seeps in Papa New Guinea Natural experiment for what happens with more CO2 levels Around ares where CO2 is seeping through, there are not many corals growing there (maybe massive porites)
How is an understanding of the disturbance regime intimately related to any discussion of the ecology and conservation issues affecting the Wet Tropics World Heritage forests and the Great Barrier Reef Marine Park?
Disturbance is discreet things that happen that will disrupt ecosystem, community, and population structure and changes resources, substrate availability, or the physical environment When thinking about distubance, it is important to think about Frequency Extent of disturbance (area) Intensity Wet Tropics Disturbance regimes deeply impact Experience abiotic, biotic, and human-related disturbances Cyclones and fire are the two big ones Species diversity and level of disturbance has bell shaped curve Diversity is lowest when there is regular, high intensity levels of disurbance (pioneer species do well here), but old growth species suffer Diversity is a bit higher at really low levels of disturbance Don't have any pioneers that grow after disturbance (just old growth forest) Intermediate disturbance is the sweet spot Old growth and pioneers Caused by disturbance impacts Treefals Defoliation Landslides Great Barrier Reef The three major disturbances and threats are Crown of thorns starfish, cyclones, and coral bleaching Super important when talking about conservation because we have a big impact on cyclones and coral bleaching with climate change Climate change leads to more coral bleaching and more severe cyclones Generally, disturbance is detrimental to the reef, can recover afterwards Understanding disturbance important because it effects what reefs look like, what inhabits them
Use an ecologist's perspective to argue that Aboriginal culture was highly adapted to the ecology of the Australian landscape. Give examples of both challenges provided by the Australian environment and Aboriginal cultural adaptations towards those environmental constraints and challenges.
Dry grass prone to fire If burning happens fairly early, grass can regenerate quickly Aboriginal people used this: managed the landscape so that there would be fresh grass, then the wildlife comes to them and they can hunt Aboriginal burning was widespread 40,000 years ago increase in charcoal sediments - probably when the burning started by Aboriginal people Proteaceae: 5% of species in the wet tropics Floral structure Produce abundant nectar Used by Aboriginal people to get sugary nectar, not many sugar sources Aboriginal people use different parts of the landscape at different times, local migration
Though they cover only 0.2 percent of the ocean's floor, scientists estimate that nearly one million species of fish, invertebrates, and algae can be found in and around the world's coral reefs. Describe the 3 main ecological reasons why corals are important to biodiversity in detail.
Foundation species - dominant primary producers Primary producers (usually plants and other photosynthesizers) are the gateway for energy to enter food webs What is a primary producer? organisms that manufacture, through photosynthesis, new organic molecules such as carbohydrates and lipids from raw inorganic materials Structural Habitat/Engineer Maintaining a positive carbonate balance Carbonate budget: the net rate of carbonate production within a given reef or carbonate sedimentary environment Corals use calcium carbonate from the environment to build their internal skeleton, helping manage the amount of CaCO3 in the ocean (higher amounts of this can be detrimental for biodiversity) Provide shelter, a place to hide for species Food Coral-feeding organisms Rates of coral consumption: butterfly fish consume up to 6% of the standing biomass of corals per year Fishes depend on coral for food, shelter, habitat A lot of fish will feed on coral gametes
Why are herbivores so important on coral reefs?
Fundamental to reefs Herbivores eat algae and keep them from completely outcompeting with coral, degrading the reef help to maintain the balance between corals and macroalgae on reefs. There are different groups of herbivores. Each group helps corals in different ways Croppers remove the upper portions of the algae (and associated epiphytic material), and in doing so prevent the growth and development of macroalgal species scraping taxa remove pieces of the substratum together with the algae, clearing space for the settlement of other organisms excavating taxa remove large amounts of carbonate material when feeding and play an important role in external bioerosion. Scaridae (parrotfish) feed on algae, make sure that it doesn't overtake corals, open up new space for coral larvae to settle on
What is the value of vegetation structural classification systems like we used on the rainforest trip pro-formas? How does that approach (analysis of the structural elements of the habitat) lend itself to rainforest systems specifically and habitats in general? Consider in your answer how this sort of classification may be used in temporal as well as spatial approaches to habitat assessment
Gives general idea of the rainforest just from soil, rainfall, and elevation information Utilizes special life forms that are more identifiable Designed to look at structural complexity: can understand a lot of what is going on ecologically without knowing a single species Important in restoration Give a good general understanding of what is going on in a habitat but is also accessible to many types of people Good for a quick assessment of a habitat that is still pretty accurate
"The influences of nutrient poverty and occurrence of fire have greatly influenced the evolution and ecology of Australian flora and fauna." Explain this statement using appropriate examples of Australian species and/or groups, noting how their ecological adaptations may be attributed to these influences.
Plants have adapted and animals have evolved to this adaption Paperbarks like acacias and eucalypts that do better on poorer soils Eucalyptus resilient to fire Have adaptations to survive fires Lignotubers are associated with the roots of the tree, close to the surface to regenerate, if they're too close to the surface a fire can kill them Lignotubers can survive even if the rest of the tree is burned Bark of the tree survives and buds (growth centers) epicormic buds underneath the bark can regenerate Dominate forests because they are resilient Plants want to maintain nutrients, so they don't want things eating their leaves (where nutrients like nitrogen are stored), once you have the leaves, there is plenty of carbon, oxygen, sunlight to photosynthesize Like acacias, except koalas have adapted to be able to eat them, Koalas have evolved to deal with adversity of the eucalyptus (even though it is toxic) Before they drop their seeds, they have capsules around them, woody capsules, get heavier and thicker and woodier because birds try and chew in there and eat the seeds (evolving to bigger beaks to break hard, woody pods protecting seeds) Parrots have upper mandible hinged, help to break the seeds Nutrients at the surface of the soil at low fertility sites, so buttress roots have become an evolutionary tactic of plants Having surface, lateral roots Amount of roots: Increase surface area as much as possible, increase number of roots and root hairs: hairlike extension of the roots making a root network Fungal associations on the roots, can be covered with fungal mat that can take in nutreints (covers the roots), also just makes surface area larger Put resources into secondary functions to make the leaves toxic so they won't get eaten to conserve nutrients Coral reefs actually do better in nutrient poor water Efficient nutrient recycling
Explain why the concept of habitat "refugia" is so important in future global conservation efforts for rainforests and coral reefs, but also habitats in general. How can refugia be identified and what strategies can be used to try and ensure that refugia are maintained locally?
Refugia are areas in which a population can survive through an extended period of unfavorable conditions. This is becoming increasingly important as the temperature of our planet increases and things are becoming less and less stable Will allow some species to survive and persist even while others may not make it Climate models can help identify refugia within the landscape; in some refugia, temperatures can be up to 6°C cooler than ambient surround- ing temperatures. suitable which occur within the current geographic range of a species. Higher elevation sites tend to be diverse, more stable Wetter locations are also more likely to be refugia Preventing logging or habitat destruction in those areas of rainforest, preventing tourism from refugia on the GBR Prevent the destruction of these habitats while we try to get climate change under control
Discuss briefly the environmental limitations to coral growth and the factors that affect the global distribution of coral reef complexes.
Temperature Corals generally cannot grow n water cooler than 18 degrees or hotter than 31 degrees, The warmer it is, the faster corals grow Light availability Hermatypic corals are generally zooxanthellate, relying on light for photosynthesis Solar irradiation partly explains latitudinal variation in coral growth, but is more important with respect to depth CaCO3 saturation, > 3.4 aragonite Covaries with temperature and drops below the level necessary to sustain reef growth at tropical limits As atmospheric CO2 levels increase the saturation of Ca CO3 increases The tropical belt has the right aragonite concentration, with higher CO2 levels those will disappear, corals won't be able to grow anymore Nutrient concentration Inversely correlated with temperature Corals can withstand moderate levels of nutrients, but are often outcompeted by macro-algae in areas with excess nutrients Salinity (need 25-42 ppt) Hydrodynamic forces Hard substrate Global distribution of coral reefs: all concentrated within 30 degrees north and south of equator, that is the tropics, need warm water to grow A few outliers because the currents that push warm water further north and south so reefs can still grow Global coral reef area: 284,300 km squared (<.2% of ocean area) Mostly along the margins of continental shelves (where it is more shallow)
Why is the biota (plants and animals) of Australia often described as "unique"? Do you agree with this description (why/why not)?
Yes I do Major concentration of endemic species in Australia, and particularly in the Wet Tropics Physical separation from other land masses for so long has caused evolutionary divides that mean that Australia has a lot of unique species Has many unique animals Only egg-laying mammals in the world are in Australia (Echidnas and platypus) Tasmania has the largest carnivorous marsupial in the world that is endemic to Tasmania (Tasmanian Devil) Endemics like koalas that are unique in their diets and are only found in australia Extensive possum species that are only present in Australia (many only present in the wet Tropics) Large flighless birds, like emus, that have evolved to not fly despite having wing bones (emus only found in australia)