Exploring the Depth Coral Reefs, Mapping and Monitoring

Transcription

1 Exploring the Depth Coral Reefs, Mapping and Monitoring Dr Chris Roelfsema School Of Geography, Planning and Environmental Management

2 Our Aim To introduce you to the world of coral reef monitoring on the ground and from space How remote sensing imagery can be turned into valuable spatial information.

3 Outline What's a Coral Reef? Values and Threats Monitoring (in water and from the sky)

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5 Coral Reef Types Barrier

6 Coral Reefs Types Lagoonal Fringing (Lizard Island, GBR, Australia)

7 Coral Reefs Types Oceanic Fringing (Morea French Polynesia)

8 Coral Reefs Types Platform (Heron Reef) Photo Source: Prof. Justin Marshall

9 Coral Reefs Types Atoll (Reefs, Coral Sea)

10 Reef Geomorphic Zonation Coral Cay Lagoon Flat Crest Slope

11 Coral Reef System environments vary in specific spatial and information scales Reef Type km 2 km km m m Geomorphic Zone Benthic Community Biotope / Patch

12 Values (Biodiversity, Cultural, Economic)

13 Coral Reefs Environments have Important Ecological, Economical and Cultural values, but are threatened by human and or natural impacts. Values Coastal protection Nursery ground Biodiversity Fishing resources Recreation Carbon Threats Coastal development Run-off and Pollution Over-fishing Boating Bleaching Sea-level rise Cyclones

14 Healthy reefs need the right balance of sunlight, temperature, & water quality Managing and conserving our Coral Reefs requires scientist and managers to have information characterising these reefs in time and space.

15 Monitoring (in water and from the sky)

16 Reef Walking

17 Snorkelling or Diving Surveys Invertebrate Fish Coral, Algae Rubble, Rock Impacts Structure Chemicals Processes

18 Automated Underwater Vehicle Surveys Benthic Light Temperature

19 Sensor Characteristics Satellites capture imagery at different times, some every morning, or every 16 days, others only when its required

20 Remote Sensing Remotely monitoring the earth surface without direct contact. Passive remote sensing, capturing reflection of light on sensitive plate (Satellite image) you taking a photo of the boat Active remote sensing, sending a signal and translating the returned signal in to information (echo sounder) you are driving to fast you need to pay a fine

21 Remote sensing application to coral reefs and surrounding environments has become increasingly critical in monitoring environmental stresses to coral reefs and detecting changes in their environmental conditions.

22 Historical Research and Mapping of Coral Reefs 1. Mapping the ocean boundaries and coral reefs. (e.g. The Polynesians, Magellan, etc, ) 2. Early scientific investigations describing the coral Reefs (e.g. Cook, Darwin, etc, ) taking 3-5 years for their journeys

23 Remote Sensing of Earth Surface 1859 First Aerial Photo 1960 First Satellite observe clouds + temps 1972 Satellite Designed to look at earth surface Archive satellite imagery since 1978, each image took less then seconds to take

24 Google Earth combines remote sensing imagery with spatial data.(border of barrier reef)

25 Field Data versus Remote Sensing Data Only relative view square meters are assessed, but accurate Every square meter (pixel) that makes up an image is assessed, but relatively not as accurate However both will provide important information to help conserve the magnificent coral reefs

26 Different habitat map extent, scales & categories can be provided by object based image analysis

27 Sensor Characteristics Satellites capture imagery at different times, some every morning, or every 16 days, others only when its required

28 Fundamentals of Remote Sensing Each satellite image is made of millions of pixels Each image pixel contains a measure of reflected sunlight at specific sensitive layers bands (e.g. Blue, Green, Red, Near Infra Red) Reflected sunlight is scattered, absorbed, transmitted and reflected. Same as the photos you take

29 Cheese Cake and Remote Sensing Image(photo) Cheese Cake 1. is made of different layers 2. Each layer has another taste (e.g. strawberry, vanilla, cookies, whip cream, grape) 3. When taking a bite, it gives you the exquisite taste of something really nice Remote Sensing Image (Photo) 1. Is made of different layers 2. Each layer is sensitive for a specific light field (e.g. blue, green, red, etc etc 3. When combining the layers one can see the beautiful colours of the reef

30 Image Pre-Processing Preparing the cooking of Cheese cake 1. Buying the ingredients 2. Unpacking ingredients 3. Each ingredient has different preparation and role Pre-processing an Image 1. Taking the photo 2. Formatting the photo 3. Removing effects from the atmosphere and water Good pre-processing will lead to better taste. or information

31 ctral : Reflectance Spectral Signatures Collection Every feature on earth reflects light and has its own light reflectance signature One pixel on the ground Amount of light reflected Sediment Coral1 Coral2 Algae Blue, Green, Red, Light sensitive layer

32 Making the Cake Or Map Preparing the cooking of Cheese cake 1. The pre-processed ingredients will be mixed 2. The taste is tested in the process 3. Each gradient will be placed in a specific combination forming taste full combination Pre-processing an Image 1. Place layers on top in one image 2. Pixels are checked with field data 3. Group of pixels with same colour and texture are assigned a mapping category (e.g. coral, land)

33 To Map the Reef You need to understand what happens with Sunlight transmitted, scattered, absorbed and reflected in atmosphere, water column and bottom.

34 Light Path Changes from Air to Water (Features Look Bigger Underwater)

35 Marine Remote Sensing: Effects of water type 5 m Depth 5 m Depth Color Changes At Depth and Water Type (Features Look Less Color Full)

36 Light penetration is limited to water depth, red will be absorbed first and then blue (Divers and snorkelers, know it) Light Penetrates The Water Blue light Blue, Green, Red, NIR Light sensitive layer Red light

37 Water Depth Change The Color Of Sand When Looking From Above Water

38 Spatial scales: Spectral scales: Temporal scales: Mapping Process: Choice of Image Type Pixel size - area covered Number of light sensitive bands and location Acquisition frequency and revisit time e.g. On request Min. every 5 days 2 m pixel Blue, Red, Green e.g. twice daily 25 m pixel Light Blue, Blue, Dark Blue, Light green, Green, etc, etc

39 Field Monitoring Field monitoring is required to help make a map or to check the map Remember: When you make cheese cake you need to do some tasting of the ingredients to be sure its good.

40 Mapping Process - Field Data: Benthic & Substrate Surveys or knowledge used to describe what is on the bottom. Detailed survey Basic survey Local knowledge Expert knowledge

41 Every dot is an photo on the reef GPS towed by diver

42 Photos of the bottom, are assessed on cover of: Coral Algae, Seagrass, Sand, Rubble, Rock 200 m Yellow dots are photos

43 Benthic & Substrate Field Data Georeferenced Photo Transects 200 m Benthic Data Photo Analysis - benthic class - rugosity Photos+data: - Calibrate - Validate

44 Snorkeler vs Robot Depth 44

45 Spectral reflectance library collection to access bottom types can be differentiated with ideal optical remote sensor. Spectral Library Collection Cyano Bacteria Cyano Bacteria Spectral Reflectance Signature Digital camera for photo bottom type

46 Mapping Process Image Pre-Processing Pre-processing correction steps: 1. Radiometric 2. Atmospheric 3. Georeferencing 4. Water surface (sun glint) 5. Air water interface (Refraction) 6. Water column (water depth, chlorophyll, sediments) 7. Masking (e.g. land, clouds)

47 Simple Map: Drawing Lines Over Satellite Image

48 Simple Map: Drawing Lines Over Satellite Image

49 Simple Map: Digitising Lines and Adding a Class

50 What can you see on a map, You can find in the legend.

51 Assign category to each pixel based on colour Assign class to pixels that look the same Each group of pixels with a colour have a signature Field Data Satellite Image 100 m Check if there are any other pixels with the same signature Accuracy assessment

52 Google Earth combines remote sensing imagery with spatial data

53 Capricorn Bunker Group, Great Barrier Reef, Australia Tryon Northwest Heron Sykes Wistari One Tree Polmaise Masthead 0 10km Lamont Fitzroy

54 Coral Reefs Types Platform (Heron Reef) Photo Source: Prof. Justin Marshall

55 Island (500 m x 800 m) 50% National park 25% Resort (200 guest staff) 25% Research Station (100 research/students + 10 staff)

56 Mitchell Australia PhD Student Seagrass Boat support Heron Island Research Station, UQ Douglas Volunteer Diver Javier Peru Postdoc Sea Level Rise Rodney Cuban PhD student Diver

57 Labortory Class Rooms Explaining in the field Exploring Underwater

58 Experiments Facilities Boating Support Diving Support Boats launched from the beach

59 Turtles come a shore to lay eggs Coral Cay and Reef birds living on the island Healthy coral cover, one 2800 Great Barrier Ree Monitoring coral reefs: Above Water

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61 Monitoring coral reefs: Underwater

62 Satellite Image + photos taken underwater Map Turning Every Pixel into a Class

63 Making a Geomorphic Map of The Reef

64 Making a Benthic Map of The Reef

65 2001 June 2006 August 2011 May 2002 May 2007 July 2011 Nov 2004 May 2005 May 2008 Oct 2009 Dec Not only once, but many times for when there is field and image data

66 Heron Palau Fiji and what about large reefs (>300 km 2 )?? Other reefs vary in: Reef composition (e.g. coral, seagrass, algae) Water depth

67 Large Reef - (>300 km 2 )

68 Detecting Coral Bleaching In The Field Out in the field, simply compare the brightness of the coral colours with the brightness of the colours on the chart and record matching codes.

69 Predicting Coral Bleaching from Space Sea surface Wind Light Availability Sea Surface Temperature To monitor and manage coral bleaching events a variety of remote sensing data is used (temperature, light availability, wind) to predict bleaching hot spots. Hotspot for Coral Bleaching

70 Determining Where Sea Surface Plankton is, Food for Mantas, Whales and Many Fish Species 1km Original Seawifs Image Each pixel contains : 1: 412nm 2: 443nm 3: 490nm 4: 510nm 5: 555nm 6: 670nm 7: 765nm 8: 865nm 100 EMPIRICAL APPROACH Chlorophyll a concentration Chl a (mg/m 3 ) = R(490nm) R(555nm) Output = = mg/m 3 Estimated absorption (%) Action spectrum of photosynthesis Chlorophyll b Carotenoids Chlorophyll a Wavelength (nm) After Raven et al. (1999:131) Rate of photosynthesis (as % of rate at 670nm)

71 2.4 Temporal Source: Seawifs 7

72 Workshop Google Earth Data files (kml) Reef monitoring sites Reef temperature Reef Impacts Find reef types?

73 Acknowledgements and Contacts Staff and Students University of Queensland Various Research Grants Research Stations in Heron, Moreton Bay, Fiji, Palau People of Fiji, Palau, Cook Island, Solomon's, Indonesia, Belize Chris Roelfsema

74 Workshop Start computer Login Start internet explorer and login with same login to get access to internet Close internet explorer Start Google Earth

75 Explore Reefs First go to GBR and see reef types Pick a reef and zoom in and see the detail present See differences in colour and water depth

76 Add Information in google earth Kml or kmz files spatial data located in s: /Student/courses/Geographyday Open GBR reef kml, and find the name of a reef and its extent Open Reef Temp find reef areas with high temperature Open reef monitoring site find reefs where monitoring take place

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