Stage 6 Senior Science

Transcription

1 Stage 6 Senior Science The Disappearing Microbats of Scheyville National Park Photo credit: Andrew Scott Student Workbook 2017 Name:. Produced by Longneck Lagoon Environmental Education Centre Website: 1

2 Local environment investigation: The back story Vampire bats! Blind as a bat! Flying rats! These are things you have probably heard before, but do you REALLY know much about the only group of flying mammals in the world? Bats or Chiroptera are among the most diverse and successful mammal groups with at least 1,000 different species worldwide! They can weigh as little as 1.5g (about as much as a cube of sugar) or as much as 1.6kg (a small Chihuahua dog) and have many different niches and jobs in various habitats. Within Scheyville National Park there is an ongoing study to determine what bat species are present, with a particular focus on echolocating bats (the little ones). These bats use sound to hunt down their prey (mostly insects) and are much smaller than the flying foxes people are used to seeing flying overhead. Humans rely on echolocating bats and fruit bats much more than we realise. The fruit bats pollinate trees, shrubs and other plants (including eucalyptus trees, guavas, mangoes and bananas) and they disperse seeds over vast distances to help plant our forests. Echolocating bats are natural pest controllers eating massive amounts of insects that would impact on crops and plantations if left unchecked by these natural predators. Imagine the impact on people s food supply and lifestyle if we were to lose any of them. The Darug people are the Traditional Custodians of the land and waterways at Scheyville National Park and have been for tens of thousands of years, and they know the importance of bats. There are many different clans in the Darug Nation. The Cattai Clan is the local clan where Longneck Lagoon is located. The importance of different animals can be seen in the totems that are assigned to different clans throughout the Darug and other Aboriginal Nations. Bats feature among these totems. Sadly, bats around the world are disappearing at an alarming rate. There are many threatening processes which include but are not limited to: deforestation, urbanisation, feral pests, insecticide and pesticide spraying, pollution of waterways, hazard reduction burning and in the United States of America a disease called White Nose Syndrome. At Scheyville National Park there are many threatened species of bats. Today you are doing REAL research through observations and testing to clarify whether the habitat here is suitable for 5 species of threatened bats. In your team today you will determine: 1. what habitat exists and is it healthy 2. if there are safe roosting areas 3. if there is an adequate food supply through water testing and a biodiversity survey 4. what threats exist and if they are significant. 2

3 Image Name Preferred habitat Preferred roosts Preferred food Status Semi-dense forest Most flying insects Vulnerable to with forest edge extinction East-Coast Freetail Bat Mormopterus norfolkensis Who are the bats? Tree hollows Under loose bark on trees Photo credit: GB Baker Large-footed Myotis (Fishing Bat) Myotis macropus Forest with water body close-by Tree hollows Caves Mines Buildings Under bridges Mostly near water Insects that fly over water Small fish Invertebrates in the water Vulnerable to extinction Photo credit: Andrew Scott Greater Broadnosed Bat Scoteanax rueppellii Open forest along waterways Tree hollows Beetles Large insects Sometimes other smaller bats Vulnerable to extinction Photo credit: Brad Law Large-eared Pied Bat Chalinolobus dwyeri Semi-dense forest Caves and overhangs Disused wren mud nests Buildings Most flying insects Vulnerable to extinction Photo credit: Michael Pennay Photo credit: Leroy Gonsalves Eastern Bentwing Bat Miniopterus schreibersii oceanensis Semi-dense forest with forest edge Caves Disused mines Buildings Most flying insects Vulnerable to extinction 3

4 1. Does bat habitat exist? In order to determine the type and health of habitat or habitats that exist at Longneck Lagoon, we can carry out a vegetation survey. When this is conducted with a range of scientific tests we are able to identify the suitability of the ecosystem for a variety of echolocating bat species. Select 5 parameters from the list below and enter them on the following table. More information about the relevance of each parameter can be found on the following page. Terrestrial Air moisture Canopy density Leaf litter density Light Slope Soil ph Soil temperature Terrestrial 6. Herbivory Transfer your selections to page 7 of your workbook. Distribution and abundance of organisms The distribution of a species describes where it is found. When studying distribution of organisms in the field a sample of the study area is taken. This is called a transect. Abundance refers to the number of a species in a given area. This may involve actual counting but if the area is too large or the species numbers are too great, sample plots called quadrats are used. Quadrats are random and non-biased. Factors affecting distribution and abundance in a natural ecosystem Physical Chemical Biological light available water food temperature ph mates topography minerals competitors altitude oxygen disease predators carbon dioxide shelter soil type nesting sites space for shelter nesting sites 4

5 How parameters affect a terrestrial ecosystem Air moisture Moisture in the air is available for plants. Dense plant communities (such as the casuarina forest) retain air moisture by inhibiting air movement and evaporation. Canopy density The canopy level of a forest or woodland serves multiple purposes: important habitat zone provides protection from storm events controls available light to lower storeys dictates the local microclimatic conditions such as temperature and humidity. Leaf litter In a terrestrial ecosystem leaf litter: Provides nutrients to the ecosystem Helps retain moisture Provides homes for terrestrial animals Promotes bushfires for regeneration. Light Light is needed for photosynthesis. If the tree canopy is open (such as in the woodland around Longneck Lagoon) there is enough light to allow shrubs, grasses and an understorey of trees. When the canopy is closed there is very filtered sunlight and consequently the vegetation would include ferns, lichens and mosses. Shrubs would have large leaves. Slope The slope of the ground will affect drainage which will then affect soil moisture and depth of soil. Where the topography is flat conditions tend to be swampy. Alternatively, on steeper slopes the soil tends to be drier and shallower. Each plant species will have its unique requirements for soil moisture and depth. The slope of the ground is important in determining which plants grow in the ecosystem. Soil ph This refers to potential hydrogen. Plants require a specific level of ph. Soil temperature Soil temperature plays an important role in many processes which take place in the soil such as chemical reactions and biological interactions. Germination and plant growth are affected by soil temperature. 5

6 Profile Key Date: Time: Ironbark Swamp Oak Grey Box Paperbark Height 15m 10m 5m Transect: Cumberland Plain Woodland Conditions: Open woodland Forest Open woodland Grassland 0m Transect line 0m * 20m 40m 60m * 80m 100m 120m 140m * 160m Parameter Measure the chosen parameters at 3 intervals as marked on the transect line *

7 Is the habitat healthy? Abundance To count all the organisms in a given population is not usually practical so scientists have developed a variety of sampling methods to estimate the abundance of a species. A quadrat, a frame of a chosen size, can be used to mark out an area in which the vegetation or animal species is to be sampled. Quadrats can be located randomly over an area or at regular intervals along a transect. 1. Randomly place your 10m x 10m quadrat in the sample area 2. Identify the tree species you will be counting (all main trees) 3. Use density boards to measure the shrub density (some bat species rely on density of shrub species) (measure diagonals of quadrats). Quadrat No Number of major trees Shrub density Total Abundance = Total number of major trees = per 100m 2 Total area of quadrats Biodiversity Survey indication of overall health of an ecosystem Factor Area Small (<1ha) 1 Medium (1ha-20ha) 2 Large (>20ha) 3 Possible score Layers Trees 1 Shrubs 1 Herbs/Ground Cover 1 Native plants None 0 Some 1 Most 2 Weeds/exotics None 3 Some 2 Most 1 Habitat Nests/Hollows 2 Water 2 Leaf Litter 1 Logs 1 Rocks 1 Total score Circle the scores of those factors that are present. Compare your total to the table below. Biodiversity ranking Low Biodiversity: 3-5 Moderate Biodiversity: 6-8 Good Biodiversity: 9-12 High Biodiversity:

8 Trophic interactions herbivory Herbivory is a measure of the impact of herbivores on a plant. It can be used as an indicator of the health or balance of an ecosystem. The bats that we are looking for mostly feed on flying insects, in turn these insects generally feed on plants. To determine if there is enough food for the bats in this ecosystem we must look at the rate of herbivory of plants. 1. Observe (do not pick) 10 leaves from eucalyptus trees and estimate the percentage of each one which has been damaged by herbivores. Use an unbiased method such as choosing the 3 rd leaf from the end 2. When counting herbivory, count the pieces that are missing and any brown areas. See below for examples of damage. 55% 30% 35% A healthy ecosystem has 15% to 20% herbivory. Trophic interactions results table: Leaf % Eaten Gather totals from 9 other people 1 Your total: Total Average 8

9 2. Roost sites Different bats choose different sites for roosting or sleeping during the day. Some species roost by themselves (solitary species) while others may roost in small groups or up to the thousands! Maternity roost sites also exist separate to the normal sites, these are used solely by mothers raising their young. Dependent on the species, roost sites can include: caves, sandstone overhangs, mine shafts, tree hollows, under big pieces of bark, rooves, under bridges or other human constructions eg bat boxes. Throughout your day check your surroundings to see what potential roost sites exist and note them below. See some examples below. Roost site Cave Is it present? Mine shaft Building Bridge Tree hollow Loose bark Other Bats roosting behind loose bark. Photo credit: Andrew Cowan Eastern Bentwing Bats roosting inside a disused building. Photo credit: Leroy Gosalves Cave roost site. Photo credit: Leroy Gosalves Disused mine roost site. Photo credit: Leroy Gosalves Tree hollow roost site. Photo credit: Leroy Gosalves Large-footed Myotis roost site under a bridge. Photo credit: Leroy Gosalves 9

10 3. Adequate and healthy food items: water testing In order to determine if there is sufficient food biodiversity to support our echolocating bat species, we can identify potential food sources by trapping and looking at what lives in the local waterways. To determine the health of the aquatic ecosystem and therefore the food sources we will look at biological indicator species and complete water testing. Select 5 parameters from the list below and enter them on the following table. More information about the relevance of each parameter can be found on the following page Aquatic Ammonia Dissolved oxygen ph Phosphorous Salinity Temperature Turbidity Aquatic 6. Biological indicators Now transfer your chosen parameters to page

11 How parameters affect a freshwater ecosystem Ammonia Ammonia, a nitrogen compound, indicates the presence of excessive nutrients. Levels above 0.01ppm indicate excessive runoff. Levels above 1ppm can be considered toxic to plants and animals. The main source of ammonia is animal waste. Dissolved oxygen Healthy water bodies require a level of 6ppm or above for aquatic animals to survive. Dissolved oxygen in water is derived from absorption from the air, water plants and the aeration of water. ph ph values below 5 and above 9 could be regarded as polluted. Values between 6.7 and 8.6 can support healthy fish populations. Phosphorus While phosphorus is a natural and vital nutrient in our ecosystems, changes in land use have radically altered the amounts of phosphorus being delivered to our waterways. Phosphorus is found as phosphate in lawn and garden fertilisers and enters waterways through runoff. It also enters waterways via the sewerage system as it is found in various household cleaners. Eutrophication is the enrichment of nutrients which may lead to excessive plant growth and the choking of waterways. Salinity (salt) Average freshwater readings are 150ppm. Above 350ppm is considered brackish and above 1900ppm significantly inhibits the growth of many organisms. The salt enters the lagoon by rising ground water and runoff. Temperature Lower water temperatures usually retain higher levels of oxygen. High temperatures in association with increased nutrients may cause algal blooms and reduced oxygen levels. Turbidity Turbidity refers to the clarity of water. It is caused by particles of dirt and algae suspended in the water. High turbidity reduces the penetration of sunlight inhibiting photosynthesis in water plants. Plants are an important part of the ecosystem as they provide food, habitat and oxygen, and absorb nutrients. Levels of around 30ppm are considered moderate while above 100ppm are considered excessive. European Carp are a common cause of increased turbidity as their feeding habits prevent the dirt from settling to the bottom. 11

12 Aquatic testing results Parameter Result Pollution index Poor 0-20 Fair Good Excellent Biological indicators Food items and biological indicators Circle number if animal found Add scores to calculate pollution index. Macro-invertebrate Common name Tolerance measure Bat food source & sensitivity Very sensitive Stonefly nymph 10 Mayfly nymph 9 Dobsonfly larva 8 Caddisfly larva 8 Sensitive Water mite 6 Beetle 5 Freshwater shrimp 4 Tolerant Dragonfly nymph 3 Damselfly nymph 3 Freshwater mussel 3 Mosquito larva 3 Bloodworm 3 Nematode 3 Very Tolerant Backswimmer 2 Water boatman 2 Water scorpion 2 Water strider 2 Worm 2 Leech 1 Freshwater snail 1 Total Potential food items: Food items are listed below in the Biological Indicators table. Write the number of potential food items in the box below. Additional food items not used in the Biological Indicators assessment can include fish and tadpoles. Tick the boxes below if you find fish and/or tadpoles and add this to your potential food number: Fish present: Tadpoles present: Other vertebrates? TOTAL number of potential food items: 12

13 4. Human impacts on the bats ecosystem History of land use The Longneck area supported a large population of Aboriginal People of the Darug Nation prior to European settlement in Evidence of this occupation is found on the lagoon margins with core stone deposits and hearths. Knowledge of the area, it s unique environment and animals is also passed down through the generations. During the 1790 s Longneck Lagoon and the surrounding woodland became part of the Nelson Common. Large areas of the woodland were extensively grazed until 1971 when Longneck Lagoon and the surrounding woodland were gazetted as a reserve. Current land use in the Longneck Catchment Scheyville National Park - educational, scientific and recreational use Farming - horse and cattle grazing, poultry farms 2-3 hectare properties - hobby farms A small urban area formerly attached to the Army Officer Training Camp. How humans impact on bats Key threats for echolocating bats: a Disturbance to roost caves/areas b Reduction in water body quality c Land clearing of habitat and adjacent to foraging areas d Introduction of diseases e Cave or other area entrances being blocked for human use/safety f Hazard fire reductions and wildfires g Application of pesticides h Loss of tree hollows i Artificial light pollution in roosting or foraging areas Use the key above in conjunction with bat species requirements on the following page to record the impact of humans in Scheyville National Park on the local bat species. Human activity Environmental impact Impact on bat species 13

14 Conclusion East-coast Freetail Bat Habitat exists Terrestrial Roost sites (require at least one) Aquatic Food Biodiversity ranking Dense shrub layer Tree hollows Caves/ bridges/ manmade roost sites Tree bark Water pollution index Airborne insect species present Fish present Y/N Result: Y/N Y/N Y/N Y/N Result: Y/N Y/N Good NA NA NA Good NA Is this habitat suitable? Should we find this species here? Threats Threats present? What is the impact? Large-footed Myotis Good Excellent Greater Broad Nosed Bat Large-Eared Pied Bat Eastern Bentwing Bat Good NA Good NA Excellent NA NA Good NA Good NA NA Good NA 14