Parks Victoria Technical Series No. 11 - Intertidal Reef Monitoring

PARKS VICTORIA TECHNICAL SERIES NUMBER 11

Victorian Intertidal Reef Monitoring Program The reef biota in Central Victoria and Port Phillip Bay Marine Sanctuaries Authors: M. Edmunds, S. P. Hart, J. Elias & B. Power June 2004

© Parks Victoria

All rights reserved. This document is subject to the Copyright Act 1968, no part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means, electronic, mechanical, photocopying or otherwise without the prior permission of the publisher.

First published 2004 Published by Parks Victoria Level 10, 535 Bourke Street, Melbourne Victoria 3000

Opinions expressed by the Authors of this publication are not necessarily those of Parks Victoria, unless expressly stated. Parks Victoria and all persons involved in the preparation and distribution of this publication do not accept any responsibility for the accuracy of any of the opinions or information contained in the publication.

Authors: Matthew Edmunds – Marine Ecologist, Australian Marine Ecology Pty Ltd. Simon P. Hart – Marine Ecologist, Australian Marine Ecology Pty Ltd. John Elias – Marine Ecologist, Australian Marine Ecology Pty Ltd. Bernadette Power – Marine Ecologist, Australian Marine Ecology Pty Ltd.

National Library of Australia Cataloguing-in-publication data Includes bibliography. ISSN 1448-4935

Citation Edmunds M., Hart S.P., Elias J. & Power B. (2004). Victorian Intertidal Reef Monitoring Program: The reef biota in Central Victoria and Port Phillip Bay Marine Sanctuaries. Parks Victoria Technical Series No. 11. Parks Victoria, Melbourne.

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Parks Victoria Technical Paper Series No. 11

Victorian Intertidal Reef Monitoring Program: The reef biota in Central Victoria and Port Phillip Bay Marine Sanctuaries

Matthew Edmunds Simon P. Hart John Elias Bernadette Power Australian Marine Ecology Pty Ltd

June 2004

Parks Victoria Technical Series No. 11

Central Vic & Port Phillip Bay Intertidal Reef Monitoring

Executive Summary Intertidal reefs support unique suites of species specially adapted to living under the constant influence of incoming and outgoing tides. Intertidal reef assemblages include large macroalgal species, herbivorous and carnivorous invertebrates such as gastropods and seastars as well as many suspension feeding species. Biological communities on intertidal reefs are particularly susceptible to change and impacts caused by human activities because they are in close proximity to land-based activities and are easily accessible to visitors. In Victoria, a number of intertidal reefs are protected within a system of Marine National Parks and Marine Sanctuaries. To effectively manage and conserve these important and biologically rich habitats, the Victorian Government has established a long-term biological monitoring program for intertidal reefs. Biological monitoring is done to characterise macrobenthic intertidal reef communities, identify important spatial variation in populations and communities across reefs, to determine the nature and magnitude of natural changes in species populations and communities over time and to detect impacts on species populations and communities through comparison with appropriate reference sites. Intertidal reef monitoring at locations along Port Phillip Bay and central Victoria began in April 2003. Locations ranged from Point Addis Marine National Park near Anglesea to Mushroom Reef Marine Sanctuary near Flinders. This report aims to: •

provide general descriptions of the biological communities and species populations at each monitoring site in April 2003ñJuly 2003,

•

identify any unusual biological phenomena such as interesting or unique communities or species, and

•

identify any introduced species at the monitoring locations.

Quadrats positioned randomly within a 10 x 20 m survey area at each site were surveyed for: •

mobile invertebrates, and

•

macroalgae and sessile (attached) invertebrates.

Exploratory data analysis techniques were used to provide general descriptions and comparisons of intertidal populations and communities in the Port Phillip Bay and central Victorian coastal regions. Community structure, species diversity and species abundances were analysed.

II



In terms of community structure, two predominant assemblage types of mobile intertidal invertebrates were identified: a Port Phillip Bay group, but including Mushroom Reef, and an open coast group. The species richness of mobile invertebrates was generally lower within the Port Phillip Bay region compared to the open coast. Sites in Port Phillip Bay had 5ñ10 species per 18 quadrats. Species richness on the open coast ranged from 9 to 16 species per 18 quadrats. However, differences in species richness did not reflect differences in diversity and evenness because of a high dominance of only a few species at some sites. Where there was lower diversity, the sites were dominant in individuals of the two species Austrochlea constricta and Cellana tramoserica. The brown alga Neptuneís necklace (Hormosira banksii) was the most abundant seaweed encountered. Algal turf was mostly encountered at the edges of the survey areas, lower down the shore, or on reefs with a higher amount of standing water. Small turfs of the pink coralline alga Corallina officinalis were typically observed at the edge of rock pools and other areas that remain relatively moist at low tide, such as in crevices. Corallina officinalis was observed at most sites in Port Phillip Bay but was most abundant in the survey areas of Jawbone, Mushroom Reef and Flinders West. The predominant aggregations of sessile animals observed were of the calcareous tubeworm Galeolaria caespitose, observed predominantly at the Port Phillip Bay sites, and small mussel Xenostrobus pulex, with relatively high cover occurring at Point Danger West and Point Danger. Results from the one monitoring survey allow us to describe reef community structure for a single snapshot in time. Reef communities are dynamic over short, medium and long time scales. As monitoring continues and longer-term datasets are accumulated (over multiple years to decades), the program will be able to more adequately reflect trends and changes in community or population structure as well as to identify specific ecological patterns occurring in these ecosystems.

III



Contents Executive Summary ............................................................................................................II Index of Figures and Tables ............................................................................................. VI 1 Introduction .....................................................................................................................1 1.1 INTERTIDAL REEF ECOSYSTEMS OF VICTORIA .................................................................. 1 1.2 INTERTIDAL REEF MONITORING PROGRAM......................................................................... 2

2 Methods............................................................................................................................5 2.1 SURVEY SITES AND TIMES...................................................................................................... 5 2.2 CENSUS METHODS ................................................................................................................ 12 2.3 DATA ANALYSIS ...................................................................................................................... 19

3 Results ...........................................................................................................................21 3.1 MOBILE INVERTEBRATES (METHOD A) ............................................................................... 21 3.2 SESSILE PLANTS AND ANIMALS (METHOD B) .................................................................... 34

4 Discussion .....................................................................................................................42 References .........................................................................................................................43 Acknowledgements...........................................................................................................44

V



Index of Figures and Tables FIGURES Figure 1. An example plot depicting change in an environmental, population or community variable over time (days, months or years). ...................................................................3 Figure 2. Parks Victoria Ranger, Dale Appleton, working with marine biologist during intertidal reef monitoring surveys. ..................................................................................4 Figure 3. Location of intertidal sampling sites in central Victoria and Port Phillip Bay. .........11 Figure 4. Configuration of survey lines and tape measures for the geographic positioning of random transects. ........................................................................................................13 Figure 5. A marine biologist using tape-intersect measures to place quadrat on reef; and the ìPocket PCî used to determined quadrat positions and record data.............................13 Figure 6. Quadrat with the alga Hormosira banksii and snail Bembicium nanum. ................16 Figure 7. Marine biologists counting invertebrates within quadrats during intertidal reef monitoring surveys.......................................................................................................16 Figure 8. Example of random quadrat positions for four sites. .............................................17 Figure 9. MDS plot of intertidal invertebrate assemblages (Kruskall stress = 0.09). .............21 Figure 10. Dominance-diversity curves for mobile invertebrates at each site. ......................26 Figure 11. Box plots of common intertidal gastropod abundances (per 0.25 m2)..................28 Figure 12. Size frequencies of limpet Cellana tramoserica shell length (mm). .....................30 Figure 13. Size frequencies of gastropod Austrocochlea constricta shell length (mm). ........31 Figure 14. Size frequencies of gastropod Bembicium nanum shell length (mm). .................32 Figure 15. Examples of typical flora and fauna on intertidal reefs. .......................................33 Figure 16. Box plots of seaweed abundances (% cover). ....................................................37 Figure 17. Size frequencies of Neptuneís necklace Hormosira banksii frond length (mm). ..38 Figure 18. Box plots of sessile animal abundances (% cover). ............................................39 Figure 19. Example of spatial differences in abundances for selected species based on quadrat locations at Mushroom Reef (Site 2907). ........................................................40 Figure 20. Example of spatial differences in abundances for selected species based on quadrat locations at Ricketts Point (Site 4111).............................................................41

VI



TABLES Table 1. Intertidal reef monitoring sites in central Victoria and Port Phillip Bay. ...................10 Table 2. Survey dates and start times for each intertidal survey site....................................11 Table 3. Intertidal taxa censused during the first survey in the Port Phillip Bay and Central Victoria regions. ...........................................................................................................18 Table 4. Mean abundances (per 0.25 m2) of intertidal animals in the western region, Point Addis to Barwon Heads (n = 18). .................................................................................22 Table 5. Mean abundances (per 0.25 m2) of intertidal animals in the Port Phillip Bay region, Point Cooke to Flinders (n = 18). .................................................................................23 Table 6. Diversity indices for pooled data for mobile invertebrates (n = 18) for each site. ....25 Table 7. Mean abundances (% Cover) of sessile plants and animals in the western region, Point Addis to Barwon Heads (n = 18 quadrats). .........................................................35 Table 8. Mean abundances (% Cover) of sessile plants and animals in the Port Phillip Bay region (n = 18 quadrats)...............................................................................................36

VII



1 Introduction 1.1 INTERTIDAL REEF ECOSYSTEMS OF VICTORIA Rocky intertidal reefs are restricted to a narrow fringe between fully terrestrial environments on land and fully submerged subtidal environments further offshore. Intertidal reefs in Victoria are generally restricted to headlands and points and are often isolated from each other by stretches of sandy beach. Victorian intertidal reefs vary in structure from steep sloping rock faces to relatively flat or gently sloping boulder fields and rock platforms. Weathering creates features on intertidal reefs including cobble fields, vertical steps, undulations in the reef, crevices, patches of sand, and rock pools. The influence of the regular tidal cycle is the most important determinant of the types of biota inhabiting rocky reefs. Intertidal reefs tend to experience rapid changes and extremes in environmental conditions including temperature, salinity and exposure to air causing desiccation stress. Typical algal species on intertidal reefs include the mat forming brown algae Neptuneís necklace Hormosira banksii and the green algae sea lettuce Ulva spp. Coralline algae and filamentous brown algal turfs are also often present. Less conspicuous is a thin layer of microscopic algae growing directly on the surface of the reef, which is an important food source for species of grazing molluscs. Molluscs tend to be the dominant faunal component on intertidal reefs. Herbivorous species include the limpets Cellana tramoserica and Siphonaria diemensis, as well as other species such as Austrocochlea constricta and Bembicium nanum. Molluscan predators include Dicathais orbita and Lepsiella vinosa. The small mussel Xenostrobus pulex and tubeworms such as Galeolaria caespitosa create encrusting mats on the surface of the reef. Other invertebrates on intertidal reefs include small crustaceans such as crabs and amphipods, as well as sessile animals including anemones. Fishes move in over the reef as the tide rises and can be important structuring components of intertidal reef communities. Intertidal reefs are the most accessible component of marine environments and consequently these habitats have important social and cultural values. Intertidal reefs are sometimes subject to human pressures, including collection of animals for food and fishing bait, trampling and pollution from catchment discharges.

1



1.2 INTERTIDAL REEF MONITORING PROGRAM 1.2.1 Objectives An important aspect in the management and conservation of Victorian marine natural resources and assets is assessing the condition of the ecosystem and how this changes over time. Combined with an understanding of ecosystem processes, this information can be used to manage threats or pressures on the environment to ensure ecosystem sustainability. Consequently, the Victorian Government has established an Intertidal Reef Monitoring Program (IRMP). The primary objective of the IRMP is to provide information on the status of Victorian reef flora and fauna. This includes monitoring the nature and magnitude of trends in species abundances, species diversity and community structure. This will be achieved through a solid baseline of information and future surveys at locations throughout Victoria, encompassing both representative and unique habitats and communities. Information from the IRMP will allow managers to better understand and interpret long-term changes in the population and community dynamics of Victoriaís reef flora and fauna. As a longer time series of data is collected, the IRMP will allow managers to: •

compare changes in the status of species populations and biological communities between highly protected marine national parks and marine sanctuaries and other Victorian reefs,

•

determine associations between species and between species and environmental parameters (e.g., exposure, reef topography) and assess how these associations vary through space and time,

•

provide benchmarks for assessing the effectiveness of management actions, in accordance with international best practice for quality environmental management systems, and

•

determine the responses of species and communities to unforeseen and unpredictable events such as marine pest invasions, mass mortality events, oil spills, severe storm events, and climate change.

A monitoring survey gives an estimate of population abundance and community structure at a small window in time. Patterns seen in data from periodic surveys are unlikely to match changes in the real populations over time exactly or predict the size and nature of future variation definitively. Plots of changes over time are unlikely to match the changes in real populations because changes over shorter time periods and actual minima and maxima may not be adequately sampled (Figure 1). Furthermore, because the nature and magnitude of environmental variation is different over different time scales, variation over long periods may 2



not be adequately predicted from shorter-term data. Sources of environmental variation can operate at the scale of months (e.g., seasonal variation), years (e.g., El NiÒo), decades (e.g., extreme storm events) or even centuries (e.g., global warming). Other studies indicate this monitoring program will begin to adequately reflect average trends and patterns as the surveys continue over longer periods (multiple years to decades). Results always need to be

Parameter

interpreted within the context of the time scale over which they have been measured.

Time

Figure 1. An example plot depicting change in an environmental, population or community variable over time (days, months or years). The black circles denote examples of monitoring times. Note how data from these times may not necessarily reflect patterns over shorter time periods, or true maxima or minima over longer time periods. Note further how data from any window of 2 or 3 consecutive monitoring times fails to adequately estimate the patterns or variation over the longer time period.

3



1.2.2 Monitoring Protocols and Locations The IRMP uses visual census methods developed prior to the survey and detailed in Section 2.2. Following this first set of surveys, the method and data will be reviewed to provide a definitive procedure for all future surveys, to ensure a consistent and comparable time-series of data can be maintained. The IRMP was initiated in April 2003 with 14 sites established on intertidal reef habitats within, and in the vicinity of, the following marine protected areas: •

Point Addis Marine National Park

•

Point Danger Marine Sanctuary

•

Barwon Heads Marine Sanctuary

•

Point Cooke Marine Sanctuary

•

Jawbone Marine Sanctuary

•

Ricketts Point Marine Sanctuary

•

Mushroom Reef Marine Sanctuary

Figure 2. Parks Victoria Ranger, Dale Appleton, working with marine biologist during intertidal reef monitoring surveys.

4



2 Methods 2.1 SURVEY SITES AND TIMES 2.1.1 Site Establishment Intertidal survey sites were established on intertidal reefs within seven marine protected areas in the central Victoria and Port Phillip Bay regions: •

Point Addis Marine National Park

•

Point Danger Marine Sanctuary

•

Barwon Heads Marine Sanctuary

•

Point Cooke Marine Sanctuary

•

Jawbone Marine Sanctuary

•

Ricketts Point Marine Sanctuary

•

Mushroom Reef Marine Sanctuary

A reference site was established in association with each of these marine protected areas (Table 1; Figure 3). The date and time of commencement of each survey is given in Table 2. Each site was given a number in accordance with the Department of Sustainability and Environment database system for marine monitoring. At each reef, a site was established on the basis of: •

large (10 x 20 m) area of relatively similar habitat (microhabitats) throughout and generally free of rock pools,

•

generally representative of the habitat(s) throughout that locality, and

•

accessible for a reasonable period at low tide.

2.1.2 Site Descriptions Point Addis Marine National Park (Site 3109) The main intertidal reef at Point Addis is a large and prominent tongue of intertidal platform that extends east from the base of cliffs northeast of Point Addis. This reef is long and is undulating in places. Large areas of this reef remain inundated during many tidal cycles and this reef appears to be exposed to high wave action. The survey site is on a smaller patch of reef that directly fringes the smaller coastal cliffs. It is a low-relief, uneven reef that drops more steeply at its edge to the subtidal zone. Undulations in the reef caused by weathering create patches of standing water. 5



The intertidal reefs are exposed to the south and east. The Point Addis headland provides some protection from southwest winds and swell, although large waves from the southwest can wrap around Point Addis onto these reefs.

Winkipop (Site 3902) The intertidal area at Winkipop is a very low-relief, gently sloping reef. The area exposed at low tide is between 30 to 50 m wide. This area is exposed to large southerly swell. The intertidal reef however may be relatively sheltered from most of the wave energy because of its gently sloping nature well out into the subtidal zone. There is a narrow band of sandy beach on the landward side of the reef. Undulations in the reef surface due to weathering create patches of standing water. This reef may be periodically subject to some sand inundation. Winkipop is a reference site for Point Addis Marine National Park.

Point Danger Marine Sanctuary (Site 4102) The intertidal area at Point Danger is a large sandstone reef platform that is an extension of the Point Danger headland. The reef is exposed to the north, east and south, however most of the prevailing weather and waves are from the south and southwest. Most of the intertidal area is relatively sheltered from large waves due to the large size of the platform. There are large areas of sandy beach to the west and north of the platform. Most of the reef is affected by sand inundation, with a thin layer of sand being present in many quadrats. The survey site is in the nearshore region of the platform.

Point Danger Reference (Site 4101) Point Danger Reference is separated from the Point Danger intertidal platform by a short section of sandy beach. This intertidal area is a low-relief sandstone reef that has been weathered to create an uneven surface at the scale of tens of centimetres. This reef has a southerly aspect and is probably more exposed to waves than the Point Danger platform. This reef is subject to significant sand inundation because of its proximity to high energy sandy beaches. Point Danger Reference is a reference site for Point Danger Marine Sanctuary.

6



Barwon Bluff Marine Sanctuary (Site 4104) The intertidal reef at Barwon Bluff is composed of sections of sandstone and basalt reef. The intertidal rock platform extends from the end of Barwon Bluff as a pincer-shaped reef. The northeastern section of the pincer is a basalt platform and boulder reef. This section of the reef is relatively protected from swell but has a large estuarine influence from the adjacent mouth of the Barwon River. The southwestern section of the pincer is a relatively flat sandstone reef, which is more exposed to large swells and sand inundation due to its exposure towards the south and proximity to an adjacent surf beach and strong longshore currents. The survey site is on the sandstone section of the reef.

Barwon Beach (Site 4103) To the west of the intertidal platform at Barwon Bluff there are several smaller isolated patches of intertidal sandstone reef. These reefs are directly exposed to large southerly swells and sand inundation due to their proximity to the adjacent surf beach and strong longshore currents. The reef surface has been weathered to create an uneven surface at the scale of tens of centimetres. The reference site for Barwon Bluff Marine Sanctuary is positioned on one of these large isolated patches of reef.

Point Cooke Marine Sanctuary (Site 4107) The intertidal area at Point Cooke is a relatively flat and extensive basalt rock platform and boulder field. Patches of sand and intertidal seagrass occur in some sections of the intertidal area which extends from Point Cooke several hundred metres to the west. The survey site was positioned on the largest continuous area of reef to the west of Point Cooke. A suitable reference site, with intertidal habitat similar to that at Point Cooke could not be found. However, the intertidal areas at Altona and Williamstown will be used as reference areas for Point Cooke Marine Sanctuary.

Altona (Site 4108) The intertidal area at Altona consists of a basalt boulder field. The large basalt boulders create considerable structure in the reef by providing large areas of vertical rock face and crevices. This intertidal area has an estuarine influence due to the proximity of Kororoit Creek. The intertidal reef at Altona is a reference area for Jawbone Marine Sanctuary as well as Point Cooke Marine Sanctuary.

7



Jawbone Marine Sanctuary (Site 4109) There is an extensive area of fractured basalt reef and boulder field at Jawbone Marine Sanctuary. The reef forms a band up to 30 m wide and extends for several hundred metres from the point at Jawbone to the boundary of the sanctuary. The large basalt boulders create medium to high relief intertidal reef with considerable structure due to the provision of large areas of vertical faces and crevices. The intertidal reef at Jawbone Marine Sanctuary has a large estuarine influence due to the proximity of Kororoit Creek and there is an area of mangrove and saltmarsh habitat at the eastern end of the sanctuary. This area abuts a RAMSAR site and is an important habitat for migratory shorebirds.

Williamstown (Site 4110) The intertidal area at Point Gellibrand, Williamstown is similar to Jawbone Marine Sanctuary in being composed of a fractured basalt reef and boulder field. However, there is less vertical structure and fewer crevices at Williamstown. The intertidal reef at Williamstown also has a southwesterly aspect. The intertidal reef at Williamstown is a reference site for Jawbone Marine Sanctuary as well as Point Cooke Marine Sanctuary.

Ricketts Point Marine Sanctuary (Site 4111) The intertidal reef at Ricketts Point Marine Sanctuary is a low relief basalt rock platform. There are some relatively small isolated rock outcrops and patches of cobbles and small boulders. The reef has a southwesterly aspect and can be subject to steep, short period waves during southwesterly storms. The survey site was positioned on the area of intertidal reef that is an extension of Ricketts Point itself.

Halfmoon Bay (Site 4112) The intertidal area is less extensive at Halfmoon Bay than at Ricketts Point. At Halfmoon Bay there are areas of low-relief fractured basalt reef and cobble fields, as well as some intertidal seagrass. The reef has a southwesterly aspect. The survey site was located on low-relief fractured basalt reef north of the jetty at Halfmoon Bay. The intertidal reef at Halfmoon Bay is a reference site for Ricketts Point Marine Sanctuary.

Mushroom Reef Marine Sanctuary (Site 2907) Mushroom Reef is a basalt intertidal reef that is in the shape of a mushroom when observed from the air. There is a large intertidal isthmus (the stem of the mushroom) that is composed of basalt pebbles and boulders. Sections of the isthmus tend to inundate with water soon after the tide begins to rise. The head of the mushroom is low-relief but uneven basalt reef with some pebbles and boulders. The highest section of the reef is the centre of the head of 8



the mushroom. This area slopes away gently to the subtidal at its outer edge. Mushroom Reef is exposed on all sides, but is protected from large swell by shallow reef further offshore. The survey site at Mushroom Reef was positioned at the south eastern side of the head of the mushroom.

West Flinders (Site 2908) The intertidal area at West Flinders is a low-relief gently sloping basalt reef with occasional vertical steps and boulder outcrops. Patches of sand covered areas at the lowest reef extent. The intertidal reef at Flinders back beach has a southeasterly aspect and is moderately sheltered from wind and waves from the southwest. West Flinders is a reference site for Mushroom Reef Marine Sanctuary.

9



2.1.3 Survey Times

Table 1. Intertidal reef monitoring sites in central Victoria and Port Phillip Bay. Site

3901

Site Name

Point Addis

A Position (MGA)

B Position (MGA)

Tape Dist

Offset

Easting

Northing

Easting

Northing

X1

X2

X1

X2

260118

5747082

260126

5747054

5

25

0

10

(MNP) 3902

Winkipop

262814

5749936

262804

5749912

5

25

0

10

4001

Pt Danger West

266069

5752994

266043

5752986

1

21

0

10

4002

Point Danger

266393

5753097

266387

5753065

9

29

0

10

(MS) 4003

Barwon West

280802

5759026

280785

5759036

5

25

0

10

4004

Barwon Heads

281279

5758946

281258

5758935

5

25

0

10

(MS) 4107

Pt Cooke (MS)

305905

5799930

305859

5799928

5

25

0

10

4108

Altona

310000

5806252

309978

5806240

5

25

0

10

4109

Jawbone (MS)

313144

5806988

313124

5807018

5

25

0

10

4110

Williamstown

315629

5806250

315616

5806232

3

23

0

10

04111

Ricketts Point

326638

5793384

326615

5793400

5

25

0

10

(MS) 4112

Halfmoon Bay

325065

5795754

325051

5795768

5

20

0

10

2907

Mushroom (MS)

327106

5738441

327111

5738419

5

25

0

10

2908

West Flinders

326436

5739005

326420

5738985

5

25

0

10

Marine National Park (MNP); Marine Sanctuary (MS).

10



Table 2. Survey dates and start times for each intertidal survey site. Site

Site Name

Date

Start Time

3901

Point Addis

25-06-03

1203

3902

Winkipop

24-06-03

1203

4001

Pt Danger West

9-07-03

1200

4002

Point Danger

8-07-03

1111

4003

Barwon West

24-04-03

1226

4004

Barwon Heads

24-04-03

0930

4107

Pt Cooke

21-04-03

1119

4108

Altona

21/23-04-03

1421

4109

Jawbone

19-04-03

1103

4110

Williamstown

23-04-03

1400

4111

Ricketts Point

20-04-03

1045

4112

Halfmoon Bay

20-04-03

1250

2907

Mushroom Reef

25-04-03

0957

2908

West Flinders

25-04-03

1227

5810000 Altona 4109 4108

4110

Poin t Cooke

5800000

4107

4112

Ricketts Point

4111

5790000

Port Phillip Bay MGA Northing (m)

5780000

Geelong

5770000

Barwon River 5760000 4003 4004 Point Danger 5750000 Point Addis

4002

4001 3902

3901 Flinders

5740000 Bass Str ait

240000

250000

260000

27000 0

280000

290000

2908 2907 300000

310000

320 000

330000

MGA Easting (m)

Figure 3. Location of intertidal sampling sites in central Victoria and Port Phillip Bay.

11



2.2 CENSUS METHODS 2.2.1 Standard Operational Procedure A draft intertidal monitoring method was developed prior to the fieldwork. The objective of this method was to ensure quality and comparability of datasets between locations and over time. The method will be reviewed following these surveys to produce a Standard Operating Procedure for use in Victorian intertidal reefs. The method details a step-by-step process for field preparations, obtaining field data, postfield procedures for managing data and procedures for training scientific observers. It was designed to minimise observer biases and error associated with visual census techniques, as well as to comply with quality and occupational health and safety policies and procedures.

2.2.2 Transect Layout and Quadrat Placement At each site, a base-line, 20ñ30 m long, was established along the shoreward margin of the survey area. Where possible, the line was placed between two distinctive features on the substratum, such as large boulders or rock outcrops. Global positioning coordinates were determined for the ends of the baseline: Position A on the left facing the sea; and Position B on the right facing the sea (Figures 4 & 5). Two weighted measuring tapes were placed on the base-line, 20 m apart, and their positions noted (usually at 5 m and 25 m). The measuring tapes were denoted Tape A (lefthand, facing seaward) and Tape B (righthand, facing seaward). Software (IQPOS: Intertidal Quadrat Positioning System), running on a pocket personal computer, was used to determine random coordinates for quadrat placements (Figure 5). This software requires the UTM coordinates for positions A and B (northings and eastings for A and B), the positions of Tape A and Tape B on the baseline (X1 and X2, normally set as 5, 25) and the offset coordinates to define the down-shore sampling region (Y1 and Y2, normally set as 0, 10). The survey area was 20 x 10 m at all sites. The output of IQPOS included x, y positions of each quadrat from the baseline, as well as tape-intersection distances and UTM coordinates. The position of each quadrat in the survey area was then marked by a numbered weight, using the intersection coordinates for the two tape measures (Figures 4 & 5).

12



20 x 10 m Survey Area

Y2

x, y

y Tape A Length

Tape B Length

Y1

AN, E

X1

x

X2

BN, E

Baseline

Figure 4. Configuration of survey lines and tape measures for the geographic positioning of random transects. The position of each quadrat was determined by the intersection distances of two tape measures extending from either end of a baseline.

Figure 5. A marine biologist using tape-intersect measures to place quadrat on reef; and the ìPocket PCî used to determined quadrat positions and record data.

13



2.2.3 Method A ñ Mobile Invertebrates The density of non-sessile invertebrates, such as gastropods and sea stars, was measured by counting individuals within 0.5 x 0.5 m quadrats (Figures 6 & 7). The observer counted all observable individuals on the rock surface or within crevices and algal fronds. To ensure the monitoring has minimal impact over time, rocks were not overturned or disturbed. Selected specimens were collected for identification and preservation in a reference collection. The shell length of 50ñ100 abundant gastropod species were measured at each site. Individuals were selected randomly by selecting the first ten individuals (of each species) encountered in or immediately adjacent to each quadrat. At the end of the quadrat sampling, additional size measurements were taken from all individuals within aggregations nearest to the observer. Size measurements were taken for Bembicium nanum, Austrocochlea constricta and Cellana tramoserica.

2.2.4 Method B ñ Macroalgae and Sessile Invertebrates The abundance of algae and highly aggregated sessile invertebrates, such as tubeworms and mussels, was measured as proportional cover of the substratum. This was done using a points-intersection method. A 0.5 x 0.5 m quadrat was divided into a grid of 7 x 7 perpendicular wires, giving 50 regularly spaced points (including one corner). Cover was estimated by the number of points directly above each species (Figures 6 & 7). Selected specimens were collected for identification and preservation in a reference collection. Where Hormosira banksii was present, the maximum frond length of 50ñ100 plants was measured at each site. Individuals are selected randomly by selecting the first ten encountered within each quadrat. At the end of the quadrat sampling, additional length measurements were taken by measuring all individuals in the patches nearest to the observer. To ensure comparability with Fox et al. (2000), the presence-absence of selected species within each quadrat was recorded (if not detected under any points). These species included the algae Ulva rigida, Cladophora subsimplex, Capreolia implexia, Ceramium flaccidum, Corallina officinalis, Hormosira banksii; and the tubeworm Boccardia proboscidea. These species are considered to be important for assessing ecological impacts at other locii on the Victorian coastline (Fox et al. 2000).

14



2.2.5 Video/Photo Quadrats Whenever weather conditions permitted, a digital photograph was taken of the substratum and biota at each quadrat position. This was done to provide a permanent qualitative record of the biota and microhabitat conditions.

2.2.6 Qualitative Observations At each site, observers made general observations of topography, reef structure (rugosity, relief, boulder sizes, etc.), biogenic habitat structure (Hormosira, algal turfs) and a general description of the flora and fauna. Video and photographic records were also taken at each site. For each quadrat, the substratum microhabitats present were recorded. These were classified as: (h) horizontal surface, flat, rock top (p) rock pool (r) rocky rubble or cobble (s) sand (v) vertical surface, rock side, crevice (e.g., Figure 8)

15



Figure 6. Quadrat with the alga Hormosira banksii and snail Bembicium nanum. The abundance of each gastropod is counted within the quadrat. The cover of macrophytes and highly aggregated animals is measured by the number of points intersecting each species on the quadrat grid.

Figure 7. Marine biologists counting invertebrates within quadrats during intertidal reef monitoring surveys.

16



r rr r

r

r r

r

r h

4107 Pt Cooke

r r

r r

r

h

r

h

r

r h

h

h

h

h

h

h

h

h

hh

h

h h

h

h

h

h

p

h

h

4109 Jawbone

h

h

h h

h

h

h

h

h

4108 Altona

h

h

h

h

h

h

h

v

h

h

h h

h

h h

h h

h h h

4110 Williamstown

h

h

h

h h

h

h

h h

Figure 8. Example of random quadrat positions for four sites. Marks indicate 2 m intervals. Legend: (h) horizontal rock surface, flat; (p) rock pool; (r) rubble, cobble (v) vertical surface, crevice.

17



Table 3. Intertidal taxa censused during the first survey in the Port Phillip Bay and Central Victoria regions. Counts per Quadrat

Counts per Quadrat

Points Cover

Anemones

Limpets

Blue-green Algae

Actinia tenebrosa

Patella chapmanii

Rivularia

Oulactis muscosa

Cellana tramoserica

Aulactinia veratra

Patelloida latistrigata

Seaweeds

Unidentified anemone

Patelloida alticostata

Algal turf

Notoacmea mayi

Enteromorpha spp.

Flatworms

Notoacmea spp.

Ulva spp.

Unidentified platyhelminth

Unidentified limpet

Ectocarpales

Siphonaria diemenensis

Hormosira banksii

Siphonaria zelandica

Thallose brown algae

Barnacles Chthamalus antennatus

Corallina officinalis

Tetraclitella purpurascens

Other Gastropods

Gracilaria spp.

Tesseropora rosea

Austrocochlea constricta

Thallose red algae

Austrocochlea odontis Other Crustaceans

Turbo undulatus

Sessile animals

Unidentified isopod

Nerita atramentosa

Galeolaria caespitosa

Unidentified crab

Bembicium nanum

Boccardia proboscidia

Nodilittorina unifasciata

Xenostrobus pulex

Chitons

Dicathais orbita

Plaxiphora albida

Lepsiella vinosa

Unidentified chiton

Cominella lineolata Onchidella patelloides

Bivalves Mytilus edulis

Seastars Patiriella exigua

18



2.3 DATA ANALYSIS 2.3.1 Analysis Strategy Exploratory data analysis techniques were used to provide general descriptions and comparisons of intertidal populations and communities in the Port Phillip Bay and central Victorian coastal regions.

2.3.2 Community Structure Community structure is a multivariate function of both the type of species present and the abundance of each species. The community structure between pairs of samples was compared using the Bray-Curtis dissimilarity coefficient. This index compares the abundance of each species between two samples to give a single value of the difference between the samples, expressed as a percentage (Faith et al. 1987; Clarke 1993). Prior to analysis, the data were log transformed to reduce the weight given to highly abundant species in describing community structure, giving a more even weighting between abundant and rarer species (following abundance transformations by Sweatman et al., 2000). The mulitvariate information in the dissimilarity matrix was simplified and depicted using nonmetric multidimensional scaling (MDS; Clarke 1993). This ordination method finds the representation in fewer dimensions that best depicts the actual patterns in higher dimensions. The MDS results were then depicted graphically to show differences between the replicates at each location.

The distance between points on the MDS plot is

representative of the relative difference in community structure. Kruskall stress is an indicator statistic calculated during the ordination process and indicates the degree of disparity between the reduced dimensional data set and the original hyperdimensional data set. A guide to interpreting the Kruskal stress indicator is given by Clarke (1993): (< 0.1) is a good ordination with no real risk of drawing false inferences; (< 0.2) can lead to a usable picture, although for values at the upper end of this range there is potential to mislead; and (> 0.2) is likely to yield plots which can be dangerous to interpret.

2.3.3 Species Diversity Species diversity involves the consideration of two components: species richness and evenness. Species richness is the number of species present in the community while evenness is the degree of similarity of abundances between species. If all species in a community have similar abundances, then the community has a high degree of evenness. If a community has most of the individuals belonging to one species, it has low evenness. Species diversity is a combination of species richness and the relative abundance of each 19



species, and is often referred to as species heterogeneity. Measures of diversity give an indication of the likelihood that two individuals selected at random from a community are different species. Species richness (S) was enumerated by the total species count per site. This value was used for calculation of evenness and heterogeneity statistics. Species diversity (i.e., heterogeneity among species) was described using the reciprocal of Simpsonís index (1/DSimpson = Hillís N2). This index provides more weighting for common species, as opposed to the weighting of rarer species such as by the Shannon-Weiner Index (Krebs 1999). The weighting of common species was considered more appropriate for this study, the sampling being directed more towards the enumeration of common species rather than rarer ones. The dominance-diversity structure of the distribution of individuals among species was examined more explicitly using k-dominance curves (Clarke 1990).

2.3.4 Species Populations The abundances of each species were summarised by calculating mean abundances for each site. The variability in abundance between quadrats was examined visually using box plots. The edges of box plots indicate the inter-quartile range and the medium is indicated within the box. The whiskers on the boxes indicate values encompassing 1.5 times the interquartile range, either side of the median. Outliers are indicated by circles. Examples of geographic differences in abundance within a site were given using bubble plots.

20



3 Results 3.1 MOBILE INVERTEBRATES (METHOD A) 3.1.1 Community Structure Two predominant assemblage types of mobile intertidal invertebrates were identified: a Port Phillip Bay group, but including Mushroom Reef (cluster to left of Figure 9); and an open coast group (cluster to right of Figure 9). The differences between these two groups were primarily because of a higher abundance of the limpets Patelloida alticostata, Notoacmea mayi and Siphonaria diemenensis and the gastropod Bembicium nanum at the coastal sites. In contrast, the limpet Cellana tramoserica and gastropod Austrocochlea constricta were more abundant in Port Phillip Bay (Tables 4 & 5). Mushroom Reef (Site 2907) was similar to the Port Phillip Bay sites because of a relatively high abundance of Austrocochlea constricta, but had affinities with the other coastal sites, primarily in a relatively high abundance of Bembicium nanum (Table 5). Point Cooke (Site 4107) was the least similar to other sites in Port Phillip Bay, largely because it had markedly low densities of all species (Figure 9 & Table 6). Barwon Heads West (Site 4003) differed from the other coastal sites in having higher abundances of the barnacle Tesseropora rosea, gastropod Nodolittorina unifasciata and small, unidentified notoacmeid limpets (Figure 9).

S4002 S2907 S3902

S4111 S4108

S3901

S4112 S4110

S2908

S4001 S4004

S4109

S4003

S4107

Figure 9. MDS plot of intertidal invertebrate assemblages (Kruskall stress = 0.09).

21


Central Vic & Port Phillip Bay Intertidal Reef Monitoring 2

Table 4. Mean abundances (per 0.25 m ) of intertidal animals in the western region, Point Addis to Barwon Heads (n = 18). Species

Site 3901

3902

4001

Actinia tenebrosa Oulactis muscosa

4002

4003

4004

0.44

1.50

0.44 0.06

Aulactinia veratra

0.11 0.17

0.06

Unidentified anemone

0.06

Unidentified platyhelminth

0.06

Chthamalus antennatus

0.89

Tetraclitella purpurascens Tesseropora rosea

14.83

Unidentified isopod

0.28

Unidentified crab

0.11

Plaxiphora albida Unidentified chiton

0.06

Patella chapmanii Cellana tramoserica

1.00

1.78

0.50

Patelloida latistrigata Patelloida alticostata Notoacmea mayi

6.06

0.78

0.39 1.11

0.22

0.39

24.33

2.33

10.17

0.78

Notoacmea spp. Unidentified limpet

0.06


0.17

1.61

Austrocochlea odontis

0.06

0.11

0.06

1.28

0.50

0.06

50.89

25.72

0.11

0.28

0.11

0.06

Turbo undulatus

0.17

0.17

Nerita atramentosa Bembicium nanum

6.17

4.89

7.33

Nodilittorina unifasciata

15.11

12.67

90.83

Dicathais orbita

0.06

0.06

0.17

0.56

Lepsiella vinosa

0.06

0.22

0.11

1.61

22

1.50

0.17

0.44 0.11



Table 4 (continued). Species

Cominella lineolata Siphonaria diemenensis Siphonaria zelandica

Site 3901

3902

4001

4002

0.06

0.50

0.17

0.17

32.11

17.78

21.39

0.78

26.17

53.39

2.39

8.11

11.94

0.28

3.11

4.61

Onchidella patelloides

4003

4004 0.83

0.06

1.28

Mytilus edulis Patiriella exigua

0.17

2

Table 5. Mean abundances (per 0.25 m ) of intertidal animals in the Port Phillip Bay region, Point Cooke to Flinders (n = 18). Species

Site 4107

4108

4109

4110

4111

4112

2907

2908

Actinia tenebrosa Oulactis muscosa Aulactinia veratra

1.50

0.83

Unidentified anemone Unidentified platyhelminth Chthamalus antennatus Tetraclitella purpurascens

0.06

0.06

0.06

Tesseropora rosea Unidentified isopod Unidentified crab Plaxiphora albida

0.11

Unidentified chiton

0.33

Patella chapmanii

0.06

Cellana tramoserica

3.50

12.44

10.61

0.11

8.89

1.00

0.50

Patelloida latistrigata Patelloida alticostata

0.44

0.17

Notoacmea mayi Notoacmea spp. Unidentified limpet

0.89 0.06

23



Table 5 (continued). Species


Site 4107

4108

4109

4110

4111

4112

2907

2908

3.39

27.67

5.06

6.11

42.56

3.44

25.06

0.22

0.06

0.83

Austrocochlea odontis Turbo undulatus

0.50

0.06

Nerita atramentosa Bembicium nanum

0.22

0.06

0.06

0.83

0.83

0.50

1.50

0.06 2.06

1.78

8.39

1.00

Nodilittorina unifasciata Dicathais orbita Lepsiella vinosa

0.06 0.17

0.17

0.06

Cominella lineolata Siphonaria diemenensis

0.39

0.39

0.94

0.17

0.06 0.17

1.00

0.61

0.67

10.67

Siphonaria zelandica

1.56

Onchidella patelloides

0.06

Mytilus edulis

1.33

0.06

Patiriella exigua

0.33

0.06

3.1.2 Dominance and Diversity The species richness of mobile invertebrates was generally lower within the Port Phillip Bay region compared to the open coast. Most sites in Port Phillip Bay had 5ñ6 species over 18 quadrats, except Jawbone and Halfmoon Bay, which had 10 species over 18 quadrats. Species richness on the open coast ranged from 9 to 16 species over 18 quadrats (Table 6). Differences in diversity and evenness did not reflect differences in species richness because of a high dominance of only a few species at some sites (Table 6). Diversity was more easily compared using dominance-diversity plots (Figure 10). Diversity was lowest at Altona and Ricketts Point (Sites 4108 & 4111), where most of the individuals in the community were Austrochlea constricta (Figure 10 & Table 6). Jawbone and Williamstown (Sites 4109 & 4110) also had relatively low diversity, with a numerical dominance of only two species: Cellana tramoserica and A. constricta. Sites with relatively higher species diversity (more sigmoidal-shaped dominance curve) were Point Danger and Point Danger West (Sites 4001 & 4002), Point Cooke and Halfmoon Bay (Sites 4107 & 4112) and West Flinders (Site 2908; Figure 10).

24



Table 6. Diversity indices for pooled data for mobile invertebrates (n = 18) for each site. Site

Site Name

N

S

N2

ESimpson

1217

13

2.74

0.21

658

14

3.23

0.23

1219

16

4.97

0.31

3901

Point Addis

3902

Winkipop

4001

Pt Danger West

4002

Point Danger

366

12

1.78

0.15

4003

Barwon West

3070

12

2.95

0.25

4004

Barwon Heads

2067

15

2.41

0.16

4107

Pt Cooke

124

5

3.01

0.60

4108

Altona

569

5

1.28

0.26

4109

Jawbone

344

10

2.01

0.20

4110

Williamstown

326

6

2.18

0.36

4111

Ricketts Point

788

6

1.06

0.18

4112

Halfmoon Bay

308

10

3.06

0.31

2907

Mushroom Reef

695

9

2.11

0.23

2908

West Flinders

315

12

2.52

0.21

(N) pooled number of individuals; (S) number of species; (N2) Hillís diversity index = reciprocal of Simpsonís Diversity; and (ESimpson) Simpsonís Evenness.

25



Cumulative Abundance %

100 90 80 70

Pt Addis

60

3101 Pt Addis 3102 Winkipop

50 40 30 1

10


100 90 Danger/Barwon

80

4001 Danger West 4002 Pt Danger 4003 Barwon West 4004 Barwon Head

70 60 50 40 30 1

10


100 Port Phillip Bay

90

4107 Pt Cooke 4108 Altona 4109 Jawbone 4110 Williamstown 4111 Ricketts 4112 Halfmoon

80 70 60 50 40 30 1

10


100 90 80 70

Flinders

60

2907 Mushroom 2908 West Flinders

50 40 30 1

10 Species Rank

Figure 10. Dominance-diversity curves for mobile invertebrates at each site. Sites with curves to the lower left of the plot have higher diversity.

26



3.1.3 Species Populations The limpet Cellana tramoserica was most abundant at Barwon Heads West (Site 4003) and in the northern Port Phillip Bay region (Sites 4108, 4109, 4110 & 4112; Figures 12a & 15). Mean densities were above 3.5 per 0.25 m2 at those sites (Tables 4 & 5). The highest sizefrequencies were between 25 mm and 40 mm, with modes at most sites between 25ñ35 mm shell length (Figure 13). Very large individuals (> 40 mm) of C. tramoserica were observed at Altona and Jawbone (Sites 4108 & 4109; Figure 13). A cohort of smaller individuals was apparent at both the Point Addis and Halfmoon Bay sites (Sites 3901 & 4112; Figure 12a). The limpet Patelloida alticostata was common on the western coastal sites, from Point Addis to Barwon Heads (Figure 12b). The densities were relatively low at these sites, average densities ranging between 0.4 and 1.3 per 0.25 m2 (Table 4). The limpet Notoacmea mayi was only observed on the western coastal sites, with high abundances at Point Addis, Point Danger West and Barwon Heads (Sites 3901, 4001 & 4004; Table 4; Figures 12c & 15). The gastropod Austrocochlea constricta was present at all sites surveyed except Barwon Heads West (Site 4002; Figure 12d). Densities were highest in the Port Phillip Bay region, particularly at Altona, Ricketts Point and Mushroom Reef (Sites 4108, 4111 & 2907; Table 6). The population size modes were variable between sites. Shell lengths were generally smaller at Winkipop, Altona, Ricketts Point and Mushroom Reef, with size modes of 12ñ20 mm shell length. Shell lengths were particularly large at Point Cooke, with a substantial proportion of shells at 24ñ28 mm (Figures 13 & 15). The gastropod Bembicium nanum was present at most sites but was most abundant at the coastal sites. Highest abundances were at Point Addis, Winkipop, Point Danger West, Point Danger and Mushroom Reef (Figure 12e). Sizes were much larger at Point Cooke than anywhere else and two size cohorts (bimodal distribution) were apparent at Point Danger West, Halfmoon Bay and Mushroom Reef (Figures 14 & 15). The pulmonate limpet Siphonaria diemenensis was only present on the coastal sites, with high abundances at Point Addis, Point Danger West, Barwon Head West and Barwon Head (Figures 12h & 15).

27



2

Abundance (per 0.25 m )

30

a. C. tramoserica

20

10

0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

2


10 8

b. P. alticostata

6 4 2 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

2


120

c. N. mayi

80

40

0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

2


80 60

d. A. constricta

40 20 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

Site

2

Figure 11. Box plots of common intertidal gastropod abundances (per 0.25 m ).

28



2


40 30

e. B. nanum

20 10 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

2


10 8

f. L. vinosa

6 4 2 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

2


5 4

g. C. lineolata

3 2 1 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

2


100 80

h. S. diemenensis

60 40 20 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

Site

Figure 11 (continued).

29


40


50

3901 Pt Addis

40

30 Count

4108 Altona

30 20 20 10

10

0

0 0

20

60

40

60

0

20

40

4001 Danger West

40

60

4109 Jawbone

50 30 Count

40 30

20

20 10 10 0

0 0

20

50

40

60

0 40

4002 Pt Danger

Count

40

40

60

4110 Williamstown

30

30 20 20 10

10 0

0 0

50

Count

20

20

40

60

0 50

4003 Barwon West

40

40

30

30

20

20

10

10

0

20

40

60

4112 Halfmoon Bay

0 0

20 40 Lenth (mm)

60

0

20 40 Lenth (mm)

Figure 12. Size frequencies of limpet Cellana tramoserica shell length (mm).

30

60


20


60

3902 Winkipop

4110 Williamstown

50 15 Count

40 10

30 20

5 10 0

0 0

10

70

20

30

40

0

10

50

4107 Pt Cooke

60

20

30

40

4111 Ricketts

40

Count

50 40

30

30

20

20 10

10 0

0 0

10

80

20

30

40

10

40

4108 Altona

70

0

60

20

30

40

4112 Halfmoon

30

Count

50 40

20

30 20

10

10 0

0 0

10

70

20

30

40

10

100

4109 Jawbone

20

30

40

2907 Mushroom

90

60

Count

0

80

50

70

40

60 50

30

40 30

20

20

10

10

0

0

0

10

20 Lenth (mm)

30

40

0

10

20 Lenth (mm)

30

40

Figure 13. Size frequencies of gastropod Austrocochlea constricta shell length (mm).

31


6


4001 Danger West

15

4110 Williamstown

5

Count

4

10

3 2

5

1 0

0 0

5

50

10

15

20

0

5

15

4002 Pt Danger

10

15

20

4112 Halfmoon

Count

40 10

30 20

5

10 0

0 0

5

7

10

15

20

0

5

40

4107 Pt Cooke

10

15

20

2907 Mushroom

6 30

Count

5 4

20

3 2

10

1 0

0 0

5

10 Lenth (mm)

15

20

0

5

10 Lenth (mm)

15

Figure 14. Size frequencies of gastropod Bembicium nanum shell length (mm).

32

20



a)

b)

c)

d)

e)

f)

Figure 15. Examples of typical flora and fauna on intertidal reefs. The examples are (a) the green alga Hormosira banksii; (b) the common limpet Cellana tramoserica; (c) the limpets Siphonaria diemenensis (centre) and Notoacmea mayi; (d) the gastropods Bembicium nanum (bottom) and Austrocochlea constricta; (e) the gastropods Cominella lineolata (top) and Dicathais orbita; and (f) the anemone Aulactinia veratra and the green alga Ulva spp. in standing water.

33



3.2 SESSILE PLANTS AND ANIMALS (METHOD B) 3.2.1 Plants Algal turf was mostly encountered at the edges of the survey areas, lower down the shore, or on reefs with a higher amount of standing water. This was particularly the case for the Point Addis and Barwon Heads sites, where the reefs surface was eroded into shallow depressions that held water. Algal turfs were most abundant in area at Point Addis, Winkipop, Point Danger, Barown Head West and Barwon Head (Tables 7 & 8; Figure 16a). The green sea lettuce Ulva spp. only abundant at Point Cooke, where it was present in all quadrats (Figures 15 & 16b). The brown alga Neptuneís necklace Hormosira banksii was the most abundant seaweed encountered within the survey plots (Tables 7 & 8; Figure 15). Hormosira banksii was most abundant at the coastal sites, particularly at Point Addis, Winkipop and Flinders West (Sites 3901, 3902 & 2908; Tables 7 & 8). There was substantial variability between quadrats at these sites (Figure 16c). The maximum frond lengths of Hormosira banksii were reasonably short at most sites, with size frequency modes of 75ñ100 mm at Point Addis, Winkipop, Point Danger West, Point Danger and West Flinders (Figure 17). Point Addis, Point Danger and West Flinders appeared to have bimodal distributions, with a smaller cohort of 0ñ50 mm long plants. Barwon Heads West and Barwon West had predominantly small plants, with the dominant size frequency modes at 75 and 25 mm respectively. Low numbers of large plants (150ñ200 mm) were observed at Point Addis, Point Danger and West Flinders (Figure 17). Small turfs of the pink coralline alga Corallina officinalis were typically observed at the edge of rock pools and other areas that remain relatively moist at low tide, such as in crevices. Corallina officinalis was observed at most sites in Port Phillip Bay but was most abundant in the survey areas of Jawbone, Mushroom Reef and Flinders West (Figure 16d).

34



Table 7. Mean abundances (% Cover) of sessile plants and animals in the western region, Point Addis to Barwon Heads (n = 18 quadrats). Species

Site 3901

3902

4001

4002

4003

4004

13.3

3.0

0.6

6.2

29.3

32.2

1.0

0.2

1.1

Blue-Green Algae Rivularia spp. Seaweeds Algal turf Enteromorpha spp. Ulva spp. Ectocarpales Hormosira banksii Thallose brown algae

0.4

0.9 1.0 25.7

1.2 63.7

15.8

19.1

11.0

17.7

0.1

0.9

1.1

2.2

0.8

Corallina officinalis Gracilaria spp. Thallose red algae Sessile animals Galeolaria caespitosa

1.0

Boccardia proboscidia Xenostrobus pulex Sand

3.0

10.6

35

25.2

13.2

25.8

18.8

0.4



Table 8. Mean abundances (% Cover) of sessile plants and animals in the Port Phillip Bay region (n = 18 quadrats). Species

Site 4107

4108

4109

4110

4111

4112

2907

2908

Blue-Green Algae Rivularia spp.

0.9

Seaweeds Algal turf Enteromorpha spp. Ulva spp.

1.9

0.2

0.4

0.9 41.7

0.4

Ectocarpales

3.2

2.4

Hormosira banksii

0.3

25.8

8.0

44.0

5.7

26.3

Thallose brown algae Corallina officinalis

0.2

Gracilaria spp.

6.6

Thallose red algae

0.8

1.1

11.2

0.8

0.2

0.8

5.6

0.3

0.4

Sessile animals Galeolaria caespitosa Boccardia proboscidia

17.2

0.2

Xenostrobus pulex

0.7

Sand

36



100

Cover (%)

80

a. Algal turf 60 40 20 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

100

Cover (%)

80

b. Ulva

60 40 20 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

100

Cover (%)

80

c. Hormosira

60 40 20 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

100

Cover (%)

80

d. Corallina

60 40 20 0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

Site

Figure 16. Box plots of seaweed abundances (% cover).

37


30


20

3901 Pt Addis

4003 Barwon West

15 Count

20 10 10 5

0

0 0

50

100

50

150

200

250

Count

50

100

40

3902 Winkipop

40

150

200

250

4004 Barwon Heads

30

30 20 20 10

10 0

0 0

50

100

35

150

200

250

4001 Danger West

30

0

50

100

9

150

200

250

4110 Williamstown

8 7

25 Count

0

6

20

5

15

4 3

10

2

5

1

0

0 0

50

30

100

150

200

250

0

50

40

4002 Pt Danger

100

150

200

250

2908 West Flinders

30 Count

20 20 10 10

0

0 0

50

100 150 200 Frond Lenth (mm)

250

0

50

100 150 200 Frond Length (mm)

250

Figure 17. Size frequencies of Neptuneís necklace Hormosira banksii frond length (mm).

38



3.2.2 Animals The predominant aggregations of sessile animals observed were of the calcareous tubeworm Galeolaria caespitosa and small mussel Xenostrobus pulex. Small patches of Galeolaria were observed predominantly at the Port Phillip Bay sites, with the highest abundance at Halfmoon Bay of approximately 17% cover (Tables 7 & 8; Figure 18a). Xenostrobus was only observed at four sites, with relatively high cover occurring at Point Danger West and Point Danger (Sites 4001 & 4002; Figure 18b). Evidence of the presence of the polychaete tube-worm Boccardia proboscidia was observed at Point Cooke (Site 4107; Table 8).

Cover (%)

60

a. Galeolaria

40

20

0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

Cover (%)

60

b. Xenostrobus

40

20

0 07 08 01 02 01 02 03 04 07 08 09 10 11 12 29 29 39 39 40 40 40 40 41 41 41 41 41 41

Site

Figure 18. Box plots of sessile animal abundances (% cover).

39




Bembicium nanum

Cellana tramoserica

Hormosira banksii

Figure 19. Example of spatial differences in abundances for selected species based on quadrat locations at Mushroom Reef (Site 2907).

40




Bembicium nanum

Cellana tramoserica

Hormosira banksii

Figure 20. Example of spatial differences in abundances for selected species based on quadrat locations at Ricketts Point (Site 4111).

41



4 Discussion This survey provided the first systematic quantitative survey of both bayside and outer coast reefs in central Victoria, enabling comparisons between reefs at both small and large scales. Previous studies encompassing larger geographic areas were qualitative or semi-qualitative (e.g., Handreck & OíHara 1994), making it difficult to compare differences between locations or between times. There has been a wealth of other intertidal studies in Victoria, but these have largely been restricted to a few locations and the measurement methods varied considerably between studies. A benefit of the techniques used in this study is that they may be comparable with two other well established long-term intertidal monitoring programs: Boags Rocks outfall monitoring since 2001 (Fox et al. 2000); and Phillip Island outfall monitoring since 1991 (Chidgey et al. 1995). The methods and their use will be reviewed following this survey. Future surveys may use a modified method. Data from this survey provides a basis for the management of both the marine protected areas and reefs outside these areas. This is through a description of existing conditions, enabling the identification of potentially important ecological aspects to be managed and the general refinement and implementation of a long-term, systematic monitoring program.

42



References Fox D., Jacoby C. and Molloy R. (2000). Eastern Treatment Plant: Monitoring the Receiving Environment. Monitoring Program ñ 2001 to 2003. Report to the Melbourne Water Corporation. CSIRO Environmental Projects Office, Melbourne. Chidgey S. S., Edmunds M. & Marshall P. (1995). Intertidal Biota at Phillip Island Wastewater Outlet, 1991, 1994 and 1995. Report to Westernport Region Water Authority. Consulting Environmental Engineers, Melbourne. Clarke K. R. (1990). Comparison of Dominance Curves. Journal of Experimental Marine Biology and Ecology. 138, 143ñ157 Clarke K. R. (1993). Non-parametric multivariate analyses of changes in community structure. Australian Journal of Ecology. 18, 117ñ143. Faith D., Minchin P. & Belbin L. (1987). Compositional dissimilarity as a robust measure of ecological distance. Vegetatio. 69, 57ñ68. Handreck C. P. and OíHara T. D. (1994). Occurrence of Selected Species of Intertidal and Shallow Subtidal Invertebrates at Victorian Locations. Report to the Land Conservation Council. Marine Research Group, Melbourne. Sweatman H., Cheal A., Coleman G., Fitzpatrick B., Miller I., Ninio R., Osborne K., Page C., Ryan D., Thompson A. and Tomkins P. (2000). Long-term Monitoring of the Great Barrier Reef. Status Report Number 4. Australian Institute of Marine Science, Townsville.

43



Acknowledgements This project was funded by Parks Victoria and supervised by Dr Anthony Boxshall. Field support was kindly provided by Mr Dale Appleton, Mr Minh Ngiemh Tran and Mr Euan Pennington.

44

Parks Victoria is responsible for managing the Victorian protected area network, which ranges from wilderness areas to metropolitan parks and includes both marine and terrestrial components. Our role is to protect the natural and cultural values of the parks and other assets we manage, while providing a great range of outdoor opportunities for all Victorians and visitors. A broad range of environmental research and monitoring activities supported by Parks Victoria provides information to enhance park management decisions. This Technical Series highlights some of the environmental research and monitoring activities done within Victoria’s protected area network. Healthy Parks Healthy People

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