Environmental change: Great Southern Reef

Virtual

Fieldwork

Photo: John Turnbull / Marine Explorer

Teachers Note: See suggestions for local fieldwork in your own region on the home page

1. ORIENTATION

This virtual fieldwork activity is taking place on the NSW Central Coast between Cabbage Tree Harbour (at Northing 17) and Pebbly Beach (at Easting 67).

Complete the Virtual Fieldwork Workbook (downloadable from the home page)

Source 1: Topographic Map

Toukley Map, Six Maps e-topo.

Source 2: Satellite Imagery ( SixMaps)

Orientation Activities: Analysing maps and images

Explore this section of coast by drone using the two video clips provided below.

i. Identify the beaches shown on the map.

ii. Observe the coast and identify areas of subtidal rocky reef. ( HINT: look for darker areas in the water)

Observe the rock platforms and geology on the coast around the lighthouse.

Think about the subtidal environment on the edge of these rock platforms. What would it look like?

Source: PhantomGaz https://www.youtube.com/watch?v=gOPnuzzHBWQ&t=2s

Follow the coastline as the drone flies north past Cabbage Tree Bay then turns and head south again. Look for the rockpool at Cabbage Tree Bay on the journey south towards the lighthouse. Look for evidence of subtidal rocky reefs for your map.

Source: The real Deal https://www.youtube.com/watch?v=YqLcfH9TSJs

NOTE: The first section of the Norah Head drone footage is to the north of the fieldwork site. It shows the lithosphere and abundance of rocky reefs along this section of coasty.

At time 4.10 minutes you reach the Rock Pool at Cabbage Tree Bay heading south. The rocky reefs you observe here will go onto your sketch map.

Orientation Activities continued.

Use SixMaps to further examine the coastal features between Cabbage Tree Harbour and Pebbly Beach. Use the NSW imagery basemap view. https://maps.six.nsw.gov.au

iii. Use the Six Maps tool to measure the length of the coast between the two locations - at the waterline. This is the extent of the kelp forest ecosystem you are visiting. See sample map below.

iv. Create a hand drawn sketch map and plot the coast between Cabbage Tree Harbour (Northing 17) and Pebbly Beach (To Eastings 67). Show the location of the rocky reefs you have observed.

v. Refer to the map scale in Six Maps OR Toukley Topographic Map (resources below) to create a scale for your map. Add the North direction. Name places.

NOTE: Sketch maps can be incorporated into HSC exam responses.

Refer to Source 3

vi. Create a field sketch of the coast. Label physical and human features. Label the beach at GR 673167 as your Weed Walk site. Shade areas of rocky reef.

SixMaps tools - distance.

This is an example of what your map might look like - make sure you only measure between the two points you were given.

https://maps.six.nsw.gov.au

Source 3: Panorama photo of the fieldwork location

Source: Richard Stanley (R a. Stanley Landscape Photography)

https://www.rastanley.com.au/?fbclid=IwAR3wnsRwTK5u6SgTTq5XllI7uQveNdd7qvD4lNgX___oHuZ5Muv1fTlSS7I

2. FIELDWORK : Key Inquiry Questions

a. What were the abiotic (non living) conditions on the day you visited?

b. Are these conditions typical for temperate kelp forest ecosystems?

c. Does the evidence suggest a high level of ecosystem biodiversity?

d. Does the evidence support the statement - 'there is a healthy, complex kelp forest ecosystem on the rocky reef along this coast'? Justify your response.

e. What values does the reef have for local communities and visitors?

f. Does your evidence support the statement - 'there are no threats to this kelp forest ecosystem?' Explain.

f. Is there evidence of effective management and protection of the marine environment along this section of coast?

3. ABIOTIC ENVIRONMENT

Analyse qualitative sources and quantitative data

You are investigating the following features of the environment recorded on September 13th 2021.

i. Geology (Lithosphere) - Source 4

ii. Atmospheric and ocean conditions September 13, 2021 - Source 5

Complete the activities in the Fieldwork Workbook.

Source 4: Lithosphere: Photographs and text L Chaffer Sept. 13, 2021

Lithosphere

Norah Head is composed of sandstone and softer shales. The rocks are horizontally bedded, helping the formation of wide rock platforms, and the rocks are well jointed in places giving them the appearance of paving stones (called 'tesselated pavement'). Large pools have formed over time due to erosion.

On the north side of Norah Head is a curving north-facing 300 m long, sandy beach with a rocky seabed, and rock platforms at either end. There are low dunes at the back of the beach. (This is the site of your Weed Walk.)

Source 5: Atmospheric and ocean conditions

a. Seawater temperatures Norah Head September 2021 and 2020

https://seatemperature.info/norah-head-waves-forecast.html

b. Ocean and atmospheric conditions on Monday 13th September

https://magicseaweed.com/South-Norah-Head-Surf-Report/4664/Historic/?start=2021-09-13&end=2021-09-20

c. Water quality

Measurements taken at the site on September 13th using a turbidity tube, refractometer and pH meter.

d. Water depth and rocky reefs

Check the location of the reefs you drew on your sketch map.

Note the water depth mapped for the NSW Marine Estate assessment.

Map: NSW Marine Estate.

https://www.marine.nsw.gov.au/marine-estate-programs/hawkesbury-shelf-marine-assessment

4. BIOTIC ENVIRONMENT

Observe, identify and measure features of the biosphere

In these activities you will take a dive to observe the kelp forests at Cabbage Tree Bay and Norah Head.

You will to learn about the biodiversity of the kelp forest on this section of coast through a study of beach wrack collected on Sept. 13th, 2021. Sources 6, 7 and 8

Complete the activities in your Fieldwork Workbook.

Take a dive: What does it look like down there?

Join a Weed Walk: What did you learn?

Beach Wrack Fieldwork

This video was filmed at Point Moore on the Great Southern Reef at Geraldton, WA. The Coastal Project Officer is talking to a group of primary school students on the importance of coastal beach wrack.

Listen to these short ABC PODCASTS: The wonders of seaweed

https://www.abc.net.au/local/stories/2012/10/02/3602275.htm

Take a Weed Walk at Norah Head - What did you find?

On a Weed Walk between Cabbage Tree Bay and Pebbly Beach this is what you observed AND collected at GR 673167 on the low tide, September 13th 2021.

Source 6. Photographs ( L Chaffer - Weed Walk, September 13th, 2021)

IMG_5027.MOV

Can you identify Golden Kelp ( Look for broad flat blades and thick stype - No gas floats); Crayweed ( Look for gas floats and narrower, ribbon like blades; Sargassum (Look for smaller, narrow blades, floats).

Source 7: Kelp Identification

ROCKY REEF ECOSYSTEM IDENTIFICATION.pdf

Source 8: Beach explorers guide

beach-explorers-guide.pdf

Source 9: % of marine algae observed in FOUR QUADRATS

A 1 metre x 1 metre quadrat used to collect data on algae proportions within beach wrack.

Source:https://www.youthmappers.org/post/2017/10/03/citizen-science-gis-program

Complete all workbook activities for the 'Abiotic Environment' and 'Biotic Environment' before completing the following activities.

Human impacts and management

Biodiversity and water quality

Source 10: Proposed Sanctuary Zone 2018

Flyer-Sydney-Marine-Park-Proposal-15.08.2018.pdf

Hawkesbury-site-Norah-Head.pdf

Ocean Outfall

Approximately 40000 KL of treated wastewater is discharged to the Pacific Ocean through 2800 meters east of Toukley Waste Water Treatment Plant on the edge of rock shelf below Norah Head Light House. There is also a point of discharge to sand dunes behind the Norah Head ocean outfall. Norah Head ocean outfall serves five wastewater treatment plants and over 25000 properties.

Monitoring of the outfall is the responsbility of Central Coast Council and data is reported on the National Outfall Database. The data is relevant for recreational water users. Impacts of waste water from ocean outfalls on marine ecosystems and biodiversity are not the focus of the database and is limited by the variables measured at each outfall. This is deternined by the outfall licence.

Visit the National Outfall database to see what data is collected at Norah Head and assess if the results indicate any threats to the kelp forests ecosystem.

Reflect and draw conclusions

Revisit and answer the Key Inquiry Questions

Suggest additional information that would help you to assess the health of the Kelp Forest Ecosystem at Norah Head and the impact of natural stresses and human impacts.