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Locating faunal breaks in the nearshore fish assemblage of Victoria, Australia

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Marine and Freshwater Research
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Marine communities are frequently biogeographically structured, despite the potential for dispersal. Previous research on a variety of marine taxa in south-eastern Australia has suggested that a biogeographic break occurs along the coastline of Victoria. However, little of this research has focussed on nearshore ichthyofauna and the location of the break remains debated. Using fish abundance measured by two methods: underwater visual census (UVC); and baited remote underwater video (BRUV) at six locations along the open coast of Victoria, we examined (1) whether there is sufficient concordance among species to indicate the presence of a faunal break; and if present (2) where any such breaks occur. Differences in assemblage composition between locations were tested with analyses of similarity and examination of residuals from regressions of pairwise dissimilarities against coastline distance. Data collected using UVC revealed two large faunal breaks co-located with a habitat discontinuity, the convergence of two currents and a thermal gradient. Data collected by BRUV revealed only a gradation of change across the study region. Greater understanding of the biogeographic structure of these communities will facilitate more effective management, especially in light of anticipated range shifts in response to global climate change.
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Locating faunal breaks in the nearshore fish assemblage
of Victoria, Australia
Madhavi A. Colton
A
,
B
,
C
and Stephen E. Swearer
A
A
Department of Zoology, The University of Melbourne, Vic. 3010, Australia.
B
Present address: California Ocean Science Trust, 1330 Broadway Suite 1135,
Oakland, CA 94612 USA.
C
Corresponding author. Email: madhavi.colton@calost.org
Abstract. Marine communities are frequently biogeographically structured, despite the potential for dispersal. Previous
research on a variety of marine taxa in south-eastern Australia has suggested that a biogeographic break occurs along the
coastline of Victoria. However, little of this research has focussed on nearshore ichthyofauna and the location of the break
remains debated. Using fish abundance measured by two methods: underwater visual census (UVC); and baited remote
underwater video (BRUV) at six locations along the open coast of Victoria, we examined (1) whether there is sufficient
concordance among species to indicate the presence of a faunal break; and if present (2) where any such breaks occur.
Differences in assemblage composition between locations were tested with analyses of similarity and examination of
residuals from regressions of pairwise dissimilarities against coastline distance. Data collected using UVC revealed two
large faunal breaks co-located with a habitat discontinuity, the convergence of two currents and a thermal gradient. Data
collected by BRUV revealed only a gradation of change across the study region. Greater understanding of the
biogeographic structure of these communities will facilitate more effective management, especially in light of anticipated
range shifts in response to global climate change.
Additional keywords: biogeographic barrier, colonisation, East Australian Current, range disjunction, Southern
Australian Current, temperate reef.
Received 22 December 2010, accepted 22 September 2011, published online 8 December 2011
Introduction
Effective resource management and conservation require an
understanding of species’ distributions in general and bio-
geographic structure in particular (Lourie and Vincent 2004).
Increasingly, managers and conservationists also need to
understand how species’ ranges may shift in response to climate
change. Identification of faunal breaks can provide insight into
the factors that determine species’ ranges, which are ultimately
limited by a species’ ability to disperse to and colonise an area
(Myers 1997) and therefore also how species may respond to
changing environmental conditions.
In numerous locations around the world, discrete faunal
boundaries have been identified in marine communities (Horn
and Allen 1978; Murray and Littler 1981; Pondella et al. 2005).
Several physical factors have been found to cause disjunctions
in the marine environment, including habitat discontinuities
(Riginos and Nachman 2001; Pelc et al. 2009), circulation
patterns (Gaylord and Gaines 2000; Pelc et al. 2009) and water
temperature (Pondella et al. 2005). Species-specific attributes
interact with these physical factors to delineate ranges. For reef-
associated organisms, which are relatively sedentary as adults,
dispersal and colonisation primarily occur during the pelagic
larval and benthic juvenile stages respectively. Although
physical barriers can limit larval dispersal, hydrodynamic
barriers caused by flow can occur in areas of continuous habitat
(Gaylord and Gaines 2000). Flow can also facilitate dispersal
(Booth et al. 2007), even though larvae have impressive swim-
ming abilities and sensory capacities (Leis and McCormick
2002). Whether larvae survive to successfully colonise will
depend on their ability to locate benthic habitat and the suita-
bility of that habitat, which will depend upon the match between
a species’ phenotype and the environment (Figueira and Booth
2010; Marshall et al. 2010, Shima and Swearer 2010) and will
also be affected by multi-species interactions (Wethey 2002;
Sexton et al. 2009).
The state of Victoria in south-eastern Australia is a complex
and dynamic region (Fig. 1) where several environmental
factors co-occur that can influence both dispersal and colonisa-
tion in temperate reef communities. First, there exists a contem-
porary discontinuity in shallow, subtidal rocky reef habitat that
stretches ,300 km across Ninety Mile Beach and the man-
groves of eastern Wilsons Promontory (Hidas et al. 2007),
although there is recent evidence that ephemeral, low-relief
deep reef is present (D. Ierodiaconou, pers. comm.). Second,
during historical glacial periods, Victoria was connected to
Tasmania via the Bassian Isthmus in what is currently Bass
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38S
SA
SAC BSW
Victoria
Melbourne
AB BH
PW
PE
Wilsons
Promontory
Bass Strait
Tasmania
ZC
BSW
SAW
SAW
0 200
km
CC
CH
NSW EAC
Ninety Mile
Beach
40S
42S
44S
142E 144E 146E 148E 150E
Leeuwin
Current
Western
Australia South
Australia
Southern Australian Current
New South
Wales
ACT
Tasmania
Victoria
Zeehan
Current
Queensland
Flindersian
Provinces
Peronian
Maugean
East Australian
Current
Northern
Territory
Fig. 1. The approximate location of major circulation patterns and three zoogeographical provinces in southern Australia
(after Whitley 1932; O’Hara and Poore 2000; Waters and Roy 2003; Ridgway and Condie 2004). Inset shows the location
of two major landmarks, Wilsons Promontory and Ninety Mile Beach and approximate circulation currents in Bass Strait
(after Gibbs 1991) using the following abbreviations: SAC, South Australian Current; ZC, Zeehan Current;
SAW, Subantarctic water; BSW, Bass Strait water; EAC, East Australian Current. The dashed line between the SAC
and the ZC indicates likely connectivity between these currents (Ridgway and Condie 2004). Acronyms in grey are
locations of study sites, with AB, Apollo Bay; BH, Barwon Heads; PW, west coast of Wilsons Promontory; PE, east coast
of Wilsons Promontory; CC, Cape Conran; CH, Cape Howe.
Faunal breaks in Victoria Marine and Freshwater Research 219
Strait (Lambeck and Chappell 2001), which created an absolute
barrier to east–west dispersal for species unable to tolerate the
cold waters at the southern end of the Isthmus. Third, Victoria is
a convergence zone for at least three distinct currents. The
Southern Australian Current (SAC) originates in Western
Australia as the warm-water Leeuwin Current, gathering high
salinity waters from the Great Australian Bight as it flows
eastward, to eventually turn southward in western Bass Strait
to become the Zeehan current, which flows as far as the south-
eastern coast of Tasmania (Ridgway and Condie 2004). The
eastern part of Victoria is influenced by the East Australian
Current (EAC) ,which brings warm waters south from the South
Equatorial Current (Ridgway and Dunn 2003). In the centre of
the state’s coastline lies Bass Strait, a shallow and fairly stagnant
body of water (Sandery and Kampf 2005) with a tendency to
eastward flow (Fandry 1983; Gibbs 1991). Bass Strait receives
input both from nutrient-rich, cold subantarctic waters and the
warm, high-salinity Southern Australian Current (Gibbs 1991;
Ridgway and Condie 2004). These complex circulation patterns
and their attendant variable temperature gradients, which are
occasionally extreme (Gibbs 1991), have the potential to limit
both colonisation and dispersal (Gaylord and Gaines 2000).
An early description of Australian zoogeography was
published by Whitley (1932), including the first map of three
provinces that overlap in south-eastern Australia: the Flinder-
sian, Maugean and Peronian (Fig. 1). A more complete descrip-
tion of bioregionalisation, based on fish composition and
richness, was developed by Lyne et al. (1996), which included
a detailed description of the zoogeographical provinces and
areas of overlap in Victoria. Describing Victoria’s biogeography
is made challenging by the presence of both east–west and
north–south influences, necessitating that this area be analysed
in two dimensions. The fish fauna in Victoria comprises
elements from: (1) the South Eastern Zootone, which extends
from Sydney to Wilsons Promontory; (2) the Bass Strait Prov-
ince, from just south of Apollo Bay to Wilsons Promontory and
south to Tasmania; (3) the Tasmanian Province, which encircles
Tasmania, with species from this province extending westward
and northward; and (4) the Western Bass Strait Zootone, which
extends from the South Australian Gulfs to slightly north of
Apollo Bay. Considering this complexity, it is unsurprising that
many species’ ranges terminate in Victoria, including those of
warm temperate species from the east coast, cool temperate
species from the south-east region, cold water species from
Tasmania and species from central southern Australia.
Research in Victoria has identified biogeographic breaks for
a variety of taxa, though few of these studies have focussed on
the nearshore ichthyofauna. The location of the disjunction has
been variously attributed to Wilsons Promontory, Ninety Mile
Beach, or range shifts associated with glacial periods. Wilsons
Promontory has long been viewed as a transition zone (Whitley
1932; Hough and Mahon 1994) and recent studies have demon-
strated that it is a site of disjunction for several taxa, including
marine echinoderms and decapods (O’Hara and Poore 2000),
littoral gastropods (Waters et al. 2005), a scyphozoan (Dawson
2005) and several fish species (Kuiter 2000; Gomon et al. 2008).
Other studies place the location of the disjunction at Ninety Mile
Beach, such as for Paraplesiops spp. (Hutchins 1987), rocky
intertidal invertebrates (Hidas et al. 2007) and some fish species
(Kuiter 2000; Gomon et al. 2008). Other studies have found taxa
to have phylogeographic structure that is best explained by the
emergence of the Bassian Isthmus (Waters and Roy 2003;
Waters et al. 2004), or with range expansions and contractions
associated with cooling temperatures during glacial periods
(Burridge 2000). Finally, at least one study has found that
contemporary population genetic structure is best explained as
the reinforcement of historical factors by present-day ocean
circulation (Waters 2008). Despite the complexity of this region,
little research has focussed on the community assemblage
patterns of its nearshore fishes.
In this study, we explored the biogeography of the nearshore
rocky reef ichthyofauna of Victoria. As discussed, there is much
evidence to suggest that Victoria is the site of range terminations
for many species, but whether these terminations co-occur for
multiple fish species at a single geographical location has not
been addressed. We sought to quantitatively explore (1) whether
there is sufficient concordance among species to indicate the
presence of a faunal break; and if so, (2) whether either of the
two previously identified locations of range disjunctions,
Wilsons Promontory and Ninety Mile Beach, is associated with
changes in community structure and whether one appears to be
associated with larger differences in community composition
than the other. We hypothesised that if the region did not contain
a biogeographic break, pairwise dissimilarities in community
assemblage structure between survey locations would be
approximately equal, whereas we expected these pairwise
differences to be large between neighbouring locations in which
disjunctions occurred.
Materials and methods
Data collection
Surveys were conducted on nearshore rocky reefs in four
locations along the coast of Victoria in south-eastern Australia
between December 2007 and June 2008. Preliminary analyses
revealed large differences in community assemblage structure
between the west coast of Wilsons Promontory and Cape Howe.
To fill the data gap between these locations, additional surveys
were conducted between March and May 2009 along the east
coast of Wilsons Promontory and at Cape Conran (Fig. 1).
Locations were selected that could be accessed by 1-day boat
trips (i.e. had proximate boat launch facilities) and in which
marine research could feasibly conducted (i.e. had a reasonable
probability of favourable weather conditions).
At each location, data were collected using both underwater
visual census (UVC) and baited remote underwater video
(BRUV) (Table 1). These two methods were chosen to capture
as much of the fish assemblage as possible, as previous compar-
isons had revealed that UVC and BRUV together provided a
more complete estimate of community composition (Colton and
Swearer 2010). Surveys were conducted on nearshore rocky reef
between 3 and 21 m depth. An exploration of habitat variation
across the region and its effects on fish assemblage composition
is detailed elsewhere (Colton 2011).
At each location sampled in 2007–08, ,24 BRUV and eight
UVC surveys were conducted; at the locations sampled in 2009,
,12 BRUV and six UVC surveys were conducted (actual
numbers of surveys varied slightly due to inclement weather
220 Marine and Freshwater Research M. A. Colton and S. E. Swearer
and technical difficulties, Table 1). UVCs were conducted by
divers on SCUBA who swam in a pre-determined direction
counting and identifying fish in the water column, on the
benthos and in the reef matrix (e.g. in crevices) along a belt
transect 5 m wide. Belt length was determined using GPS
coordinates of diver entrance and egress points (mean
s.d. ¼360 212 m). BRUV units were baited with ,400 g of
pulverised pilchards and deployed onto or next to rocky reef for
60 min. Using UVC, we measured fish density (m
2
), whereas
BRUV provided us with a measure of relative density called
MaxN.MaxN is a species-specific measure of the maximum
number of individuals observed in a 1-s interval on a BRUV
tape. Additional details are provided by Colton and Swearer
(2010).
Data analyses
Data were purged of all individuals that were not identified to
the species level, with the exception of a putative species
Trygonorrhina sp. A (Gomon et al. 2008). To reduce noise in the
data associated with poorly sampled species, only species
observed more than once per method were included in the
analyses. In addition, it was only sometimes possible to identify
to species individuals in the genus Upeneichthys as morpho-
metric differences between U. lineatus and U. vlamingii are
slight (Gomon et al. 2008). Without the ability to consistently
identify individuals to the species level, the utility of
Upeneichthys spp. to distinguish between locations diminished,
especially because Upeneichthys spp. is ubiquitous. Therefore,
all records of individuals in the genus Upeneichthys were
removed from the analysis. Taxonomic nomenclature follows
Eschmeyer and Fricke (2009).
Species distributions and habitat affinities were gathered
from field guides (Kuiter 2000; Edgar 2005; Gomon et al.
2008) and used to discuss how distributions in this study differed
from published reports (Table 2). Locations at which a species
was described as ‘rarely occurring’ near the edge of its range
were not included. Widespread southern species were defined as
those that are present in most of southern Australia (e.g. from
Queensland to Western Australia); southern species were
defined as those that are primarily Tasmanian but which occur
on the mainland in the vicinity of Bass Strait; south-central
species were defined as those that occur only on the south coast
including Tasmania, Victoria, South Australia and Western
Australia; eastern species were defined as those that occur on
the east coast including eastern Victoria but not Wilsons
Promontory; eastern in Victoria species were defined as those
which are widespread across southern Australia and yet in
Victoria are observed only in the east; and south-eastern species
were defined as those that occur on the east coast and at least as
far as Wilsons Promontory but no further than South Australia.
The lone species classified as south-western is most abundant in
southern Western Australia and also occurs in the vicinity of
Port Philip Bay.
Presence/absence data collected using the two methods were
combined to determine the maximum range of each species and
species turnover between neighbouring locations. Turnover was
calculated as the total number of species that differed between
two neighbouring locations (sensu O’Hara and Poore 2000).
Species that occurred at all sample locations on only one side of
a pair of neighbouring locations were categorised as having a
range termination and species which were observed at all
locations were categorised as ‘ubiquitous’.
Statistical analyses were performed separately on the abun-
dance data (density measured by UVC and MaxN measured by
BRUV) collected by each method because this and other
research (Colton and Swearer 2010) revealed significant differ-
ences between methods. Data were fourth-root transformed and
analyses conducted on a Bray–Curtis resemblance matrix.
To explore whether there were differences in species’
assemblages between locations, we first visualised the multi-
variate data using non-metric multi-dimensional scaling
(MDS) plots (PRIMER-E ver. 6, Clarke and Warwick 2001).
We then tested for differences in assemblage structure between
locations using the analysis of similarity (ANOSIM) routine in
PRIMER-E with 9999 permutations. ANOSIM is approximately
analogous to univariate ANOVA but operates on a resemblance
matrix (Clarke and Gorley 2006). The test statistic generated by
an ANOSIM is an R-value that measures the amount of dissimi-
larity between a priori groups of samples. Ris standardised
allowing it to be compared between studies and usually ranges
from 0, no difference between groups, to þ1, perfect dissimilar-
ity between groups. To understand whether assemblages at
particular locations were statistically similar to one another,
we used a group average clustering method to group mean MaxN
(BRUV) and density (UVC) for all species at each location. This
was accomplished using the similarity profile (SIMPROF)
routine in PRIMER-E, with significance assessed using 9999
permutations. SIMPROF is an unconstrained ordination by
permutation test for determining the number of significant
clusters.
We hypothesised that if there was little biogeographic
structure to the region, we would expect all pairwise dissim-
ilarities between locations to be equal. In contrast, if the region
contained biogeographic disjunction(s), we would expect a
dramatic change in assemblage composition over a small
distance. To explore these hypotheses, we examined ANOSIM
dissimilarities between pairs of locations as a function of
coastline distance, measured in Google Earth, using linear
regressions fitted in SPSS (ver. 16.0, Chicago, IL, US). In order
to identify locations between which large differences occurred
that were not a function of geographic distance, we plotted
regression residuals, computed as the observed value minus the
value predicted by the regression equations. Between locations
Table 1. Number of sampling replicates conducted for each method
at each location
UVC mean transect length¼360 212 m (s.d.). Location abbreviations
follow full names. BRUV, baited remote underwater video; UVC, under-
water visual census
Location BRUV UVC
Apollo Bay (AB) 24 12
Barwon Heads (BH) 17 7
Wilsons Promontory west (PW) 23 9
Wilsons Promontory east (PE) 12 6
Cape Conran (CC) 10 6
Cape Howe (CH) 24 8
Faunal breaks in Victoria Marine and Freshwater Research 221
Table 2. Species observed at each location by method
Species observed by baited remote underwater video (BRUV) indicated with b, and by underwater visual census (UVC) with u. Distribution information was
garnered from guidebooks and is described in the text. Habitat affinities represent species’ primary habitat associations based on data in guidebooks; ‘mixed’
indicates species that occur both on soft sediments and reefs. Locations are abbreviated as in Fig. 1
Distribution Species Family Habitat affinity AB BH PW PE CC CH
Widespread southern Acanthaluteres vittiger
C
Monacanthidae Reef bu bu bu bu b bu
Widespread southern Aracana aurita Aracanidae Reef bu – bu u
Widespread southern Aulopus purpurissatus Aulopidae Reef bu b – u – –
Widespread southern Cephaloscyllium laticeps
D
Scyliorhinidae Reef bu bu bu u bu
A
bu
Widespread southern Cheilodactylus nigripes
D
Cheilodactylidae Reef bu bu bu bu bu
Widespread southern Chrysophrys auratus Sparidae Mixed bu
A
bbb–bu
Widespread southern Dactylophora nigricans Cheilodactylidae Reef bu b u b – –
Widespread southern Dasyatis brevicaudata Dasyatidae Mixed b b b – – b
Widespread southern Dinolestes lewini
CD
Dinolestidae Mixed bu bu bu
A
bu bu bu
Widespread southern Diodon nicthemerus
D
Diodontidae Reef u u u u u u
Widespread southern Dotolabrus aurantiacus Labridae Reef bu u bu bu u b
Widespread southern Enoplosus armatus
CD
Enoplosidae Reef bu bu bu bu bu bu
Widespread southern Eubalichthys bucephalus Monacanthidae Reef – – – – – bu
Widespread southern Eubalichthys mosaicus Monacanthidae Reef – b – u bu b
Widespread southern Eupetrichthys angustipes Labridae Reef – u bu u bu u
Widespread southern Girella zebra
CD
Kyphosidae Reef bu bu
B
bu bu bu bu
Widespread southern Haletta semifasciata Odacidae Reef bu – – b – –
Widespread southern Heterodontus portusjacksoni
C
Heterodontidae Mixed b b b b b bu
Widespread southern Heteroscarus acroptilus Odacidae Reef bu b bu bu – u
Widespread southern Hypoplectrodes nigroruber Serranidae Reef – – – u u
Widespread southern Lepidotrigla vanessa Triglidae Mixed u – – – – –
Widespread southern Lotella rhacina Moridae Reef – – – – bu u
Widespread southern Meuschenia flavolineata Monacanthidae Reef u bu
B
bu bu b u
Widespread southern Meuschenia freycineti
C
Monacanthidae Reef bu bu bu bu b bu
Widespread southern Meuschenia hippocrepis Monacanthidae Reef bu
AB
buu–b–
Widespread southern Meuschenia scaber Monacanthidae Reef u – – – bu bu
Widespread southern Meuschenia venusta Monacanthidae Reef – – – – bu u
Widespread southern Mustelus antarcticus Triakidae Mixed – – – b b b
Widespread southern Myliobatis australis Myliobatidae Mixed bu b b b b b
Widespread southern Nemadactylus macropterus Cheilodactylidae Reef – – – u – b
Widespread southern Neoodax balteatus Odacidae Reef u – – bu u –
Widespread southern Olisthops cyanomelas
CD
Odacidae Reef bu bu bu
B
bu bu bu
Widespread southern Parequula melbournensis Gerreidae Soft sediment b bu bu bu bu
Widespread southern Parma victoriae Pomacentridae Reef bu bu bu bu –
Widespread southern Pempheris multiradiata
D
Pempheridae Reef u
B
bu
B
uuuu
Widespread southern Pentaceropsis recurvirostris
D
Pentacerotidae Reef u u bu u bu bu
Widespread southern Pictilabrus laticlavius
CD
Labridae Reef bu bu bu bu bu bu
Widespread southern Pseudolabrus psittaculus
C
Labridae Reef bu b bu bu bu
A
bu
Widespread southern Pseudophycis barbata Moridae Reef b – b b – –
Widespread southern Rexea solandri Gempylidae Pelagic – – – b – –
Widespread southern Scobinichthys granulatus Monacanthidae Reef – – u b u –
Widespread southern Scorpis aequipinnis Scorpididae Reef bu bu
A
bu
B
bu u
Widespread southern Seriola lalandi Carangidae Reef, Pelagic – – – – b b
Widespread southern Sillaginodes punctatus Sillaganidae Mixed b
A
bbub
A
––
Widespread southern Siphonognathus beddomei Odacidae Reef – – u – –
Widespread southern Sphyraena novaehollandiae Sphyraenidae Pelagic b – b b b bu
Widespread southern Tilodon sexfasciatum Kyphosidae Reef u bu bu bu –
Widespread southern Trachurus declivis Carangidae Pelagic – – – u u
Widespread southern Trachurus novaezelandiae Carangidae Pelagic b b
A
ub
A
–bu
AB
Widespread southern Trygonorrhina fasciata Rhinobatidae Mixed bu b – – –
Southern Eubalichthys gunnii Monacanthidae Reef – – – bu – –
Southern Meuschenia australis Monacanthidae Reef – u bu – – –
South-central Aplodactylus arctidens
CD
Aplodactylidae Reef bu bu bu bu bu bu
South-central Aracana ornata Aracanidae Reef – – u bu – –
South-central Caesioperca rasor
CD
Serranidae Reef bu
B
bu
A
bu
AB
bu
AB
bu bu
South-central Eeyorius hutchinsi Moridae Reef b – – – b –
(Continued)
222 Marine and Freshwater Research M. A. Colton and S. E. Swearer
in which there was a large change in assemblage (i.e. evidence
of a biogeographic break), the species responsible for the
observed differences were identified using the SIMPER routine
in PRIMER-E.
Finally, for species which showed significant differences in
abundance between neighbouring locations (for either BRUV or
UVC), we tested whether species with similar distributions,
as described by guidebooks, exhibited consistent changes
(i.e. increases or decreases) in abundance between locations
using Chi-square tests.
Results
Species turnover and range terminations
A total of 91 species were included in these analyses, of which
78 were observed using BRUV and 80 using UVC (Table 2; for
abundance data see Table S1, available in the Supplementary
Material to this paper). Twenty-one species were ubiquitous,
of which nine were observed by both methods, 14 only by
BRUV and 16 only by UVC. Some eastern species, such as
Dicotylichthys punctulatus and Pempheris compressa, were
observed as far west as Wilsons Promontory, whereas others,
such as Trachinops taeniatus and Suezichthys aylingi, were
recorded only at Cape Howe (CH). Most south-eastern species
ranged as far west as Wilsons Promontory, though Scorpis
lineolata was observed at Barwon Heads (BH) and Hypoplec-
trodes maccullochi was recorded only west to Cape Conran
(CC). The primarily Tasmanian species Meuschenia australis
and Eubalichthys gunnii were recorded only in Bass Strait at BH
and Wilsons Promontory.
Species turnover, which we defined as the number of species
found at only one of a pair of neighbouring locations, was
highest between the east coast of Wilsons Promontory (PE) and
CC and lowest between Apollo Bay (AB) and BH (Table 3).
Thirty-two species (35%) were observed at all sites to only one
side of a location, which is how we defined a range termination,
Table 2. (Continued)
Distribution Species Family Habitat affinity AB BH PW PE CC CH
South-central Platycephalus bassensis Platycephalidae Soft sediment b – b b b –
South-central Pseudophycis bachus Moridae Mixed – – u – –
South-central Trachinops caudimaculatus Plesiopidae Reef – bu
AB
u––
Eastern Acanthistius ocellatus Serranidae Reef – – – – b bu
Eastern Allomycterus pilatus Diodontidae Reef – – – b
Eastern Aplodactylus lophodon Aplodactylidae Reef – – – – bu bu
Eastern Cheilodactylus fuscus Cheilodactylidae Reef – – – – – bu
Eastern Chromis hypsilepis Pomacentridae Reef – – – – – bu
B
Eastern Coris sandageri Labridae Reef – – – – – u
Eastern Dicotylichthys punctulatus Diodontidae Reef – – – u u u
Eastern Notolabrus gymnogenis Labridae Reef – u – – bu bu
Eastern Pempheris compressa Pempheridae Reef – – u – – u
Eastern Suezichthys aylingi Labridae Reef – – – – – u
Eastern Trachinops taeniatus Plesiopidae Reef – – – – – u
B
Eastern in Victoria Gymnothorax prasinus Muraenidae Reef – – – – b bu
Eastern in Victoria Ophthalmolepis lineolata Labridae Reef – – – bu bu
A
bu
A
South-eastern Achoerodus viridis Labridae Reef – – b bu bu
South-eastern Atypichthys strigatus Kyphosidae Reef u – bu
AB
bu
B
bu
B
bu
AB
South-eastern Caesioperca lepidoptera Serranidae Reef bu bu
B
bu
AB
bu
AB
South-eastern Cheilodactylus spectabilis
D
Cheilodactylidae Reef bu u bu bu bu bu
South-eastern Chironemus marmoratus Chironemidae Reef – – – – – bu
South-eastern Girella elevata Kyphosidae Reef – – u – bu
South-eastern Hypoplectrodes maccullochi Serranidae Reef – – – – bu bu
South-eastern Latridopsis forsteri Latridae Reef bu – bu bu b bu
South-eastern Nemadactylus douglasii Cheilodactylidae Reef b bu bu
South-eastern Notolabrus fucicola
CD
Labridae Reef bu
AB
bu bu
A
bu bu bu
South-eastern Notolabrus tetricus
CD
Labridae Reef bu
AB
bu
AB
bu
AB
bu
AB
bu
AB
bu
South-eastern Optivus agastos Trachichthyidae Reef – – – u – u
South-eastern Parma microlepis Pomacentridae Reef – – u bu bu
B
bu
South-eastern Scorpis lineolata Scorpididae Reef bu bu bu
AB
bu
B
bu
A
South-eastern Tetractenos glaber Tetraodontidae Reef bu b bu – b
South-eastern Trygonorrhina sp. A Rhinobatidae Mixed b – – – – b
South-eastern Urolophus cruciatus Urolophidae Soft sediment bu u
South-western Meuschenia galii Monacanthidae Reef u bu – – – –
A
Five most abundant species for each location with BRUV.
B
Five most abundant species for each location UVC.
C
Ubiquitous species with BRUV.
D
Ubiquitous species with UVC.
Faunal breaks in Victoria Marine and Freshwater Research 223
and 23% were ubiquitous, i.e. occurred at all locations. The
majority of range terminations occurred between PE and CC
(n¼12), with a similar number occurring between CC and CH
(n¼10). Ten species (11%) had range breaks between the other
three locations.
The region did not appear to be equally permeable to
dispersal and there was some indication that species’ distribu-
tions were more limited in westward than eastward dispersal.
For example, 100% of the species with a range ending at
Wilsons Promontory occurred to the east of the Promontory,
80% of the species with a break between CC and PE occurred at
CC, and 70% of the species with a break between CC and CH
occurred to the east of CH (Table 3). Similarly, the breaks
between BH and both the west coast of Wilsons Promontory
(PW) and AB also appeared to act more as a barrier to westward
than to eastward dispersal.
Assemblage composition by location
MDS plots revealed differences between locations for both
BRUV and UVC data (Fig. 2). In both datasets, the eastern
locations, CC and CH, were clearly differentiated from the rest
of the state. In the BRUV data, the samples from the other four
locations overlapped. In contrast, the UVC data suggest that
the Wilson Promontory samples, PW and PE, were intermediate
between those from the east, CC and CH and those from the
west, AB and BH. In addition, there is some indication in
the UVC data that PE was more similar to CC and CH, and PW
more similar to AB and BH in their fish assemblages.
The SIMPROF routine was used to identify significant
clusters of locations. Both BRUV and UVC data revealed that
the eastern locations, CC and CH, formed a significant cluster
that differed from the other 4 locations (Fig. 3). In addition, there
was non-significant structuring between the other locations that
differed by methods. The BRUV data revealed that BH was an
outlier to a cluster of AB þPW þPE and PE was an outlier to
AB þPW. In contrast, the UVC data revealed two non-
significant clusters, one containing AB þBH and the other
PW þPE. These results echo those found in MDS plots
(Fig. 2), in which the UVC data suggested that the samples
from Wilsons Promontory, PW and PE, were different to those
from AB and BH, whereas the BRUV data showed overlap
between AB, BH, PW and PE.
ANOSIM revealed an overall significant effect of location
for BRUV (r¼0.44, P¼0.0001) and UVC (r¼0.66,
P¼0.0001) and all pairwise comparisons between locations
were significant for both methods (Table 4). However, there was
a wide range in the strength of R. Examining pairwise compar-
isons for only neighbouring locations, BRUV data revealed little
differences across the five comparisons (mean ¼0.24 0.07 s.d.)
whereas UVC showed both a larger range and higher values of
R(mean ¼0.57 0.27 s.d.) (Table 4). The UVC data revealed
the largest dissimilarity between PE and CC (r¼0.91), followed
by CC and CH (r¼0.69) and BH and PW (r¼0.63). The BRUV
data showed the largest difference between CC and CH
(r¼0.32), followed by PE and CC (r¼0.29) and AB and BH
(r¼0.25). The SIMPER routine was used to identify species in
the UVC data that explain differences between locations span-
ning the proposed disjunctions. Fifteen species cumulatively
explained 51.3% of the variation between CC and PE and 16
species cumulatively explained 51.1% of the difference between
CC and CH (Table 5).
Table 3. Species turnover and the number of species exhibiting range
disjunctions between neighbouring locations
Turnover is defined as the number of species that are not shared between
neighbouring locations. Species’ distribution described by a left arrow
indicates that the species occurs at that and all locations to the west and a
right arrow indicates that the species occurs at that and all locations to the
east. Locations are abbreviated as in Fig. 1
Locations Turnover Distribution No. of species
AB/BH 19 BH-2
AB 1
BH/PW 21 PW-2
BH 1
PW/PE 25 PE-4
PW 0
PE/CC 32 CC-8
CC 3
CC/CH 27 CH-7
CC 3
Ubiquitous – – 21
CH
CC
PE
PW
BH
AB
2D stress: 0.21
Location
CH
CC
PE
PW
BH
AB
2D stress: 0.16
Location
(a)
(b)
Fig. 2. MDS plots showing differences in assemblage composition for data
collected by (a) baited remote underwater video (BRUV) and (b) underwater
visual census (UVC). Locations are abbreviated as in Fig. 1.
224 Marine and Freshwater Research M. A. Colton and S. E. Swearer
Several pairs of congeneric species appeared to be separated
into eastern and western components (further phylogenetic work
is required to ascertain whether these are sister species). Cae-
sioperca rasor was observed at all locations though it was more
abundant in the west, whereas C. lepidoptera was present only in
the east. Parma microlepis was found only in eastern samples
and P. victoriae in western samples, though the species over-
lapped at Wilson Promontory. There was also significant over-
lap in the occurrence of Scorpis aequipinnis and S. lineolata,
though the former was more abundant in the west and not
observed at CH and the latter more abundant in the east and
not observed at AB. Trachinops caudimaculatus was observed
only at BH and PW, whereas T. taeniatus was recorded only at
CH. Many of these species were shown to strongly contribute to
the differences between PE and CC and CC and CH (Table 5).
Dissimilarity as a function of distance
In the BRUV data, ANOSIM Rshowed a linear relationship with
coastline distance (R
2
¼0.75, P,0.0005) (Fig. 4a). Some pairs
of locations had larger residuals around the regression than
others (Fig. 4b). For example, BH and PW were more similar
than their distance alone would suggest, as were AB – PW and
AB – CH. Some pairs of locations, such as AB – BH and
BH – CC, were less similar than distance alone would suggest.
The UVC data revealed an interesting pattern in the relation-
ship between ANOSIM Rand coastline distance (R
2
¼0.41,
P¼0.01) (Fig. 4a). Some pairwise comparisons were more
similar than predicted by their geographic distance and some
were less similar. Examination of the regression residuals
clearly illustrated this (Fig. 4b). In particular, large dissimila-
rities between CC – CH and PE – CC were evident, although
there was little difference between PW and PE.
Effect of species’ distributions on differences
in abundance between neighbouring locations
Consistent changes in abundance among species with similar
distributions occurred only between PE and CC (x
2
¼10.17,
P¼0.017; all other comparisons: 0.087 ,P.0.786). Of spe-
cies with south-central distributions, 100% were significantly
more abundant at PE and 100% of species with eastern dis-
tributions and 86% of species with south-eastern distributions
were significantly more abundant at CC. Changes in abundance
of widespread southern species were more evenly distributed,
with 62% of species significantly more abundant at PE.
BRUV vs UVC
These analyses (and previous work, see Colton and Swearer
2010) indicated that there were clear differences between the
methods we used to estimate abundance. In general, BRUV
appeared less sensitive to detecting biogeographic patterns than
UVC. For example, an MDS plot of BRUV data showed less
separation between locations than the UVC data (Fig. 2) and
SIMPROF clustering revealed similar trends (Fig. 3). The UVC
data alone suggested that the Wilsons Promontory locations
50 60 70 80
Similarity
Similarity
90 100
PW
PW
AB
AB
PE
PE
BH
BH
CH
CC
CH
CC
40 60 80 100
(a)
(b)
Fig. 3. SIMPROF clustering by location for (a) baited remote underwater
video (BRUV) and (b) underwater visual census (UVC) data. Solid lines
indicate significant clusters at P,0.05 and dashed lines represent non-
significant clusters. Locations are abbreviated as in Fig. 1.
Table 4. Pairwise comparisons in assemblage structure between
locations
Distance between locations (abbreviated as in Fig. 1) is measured as
coastline distance (km) and dissimilarity coefficients as ANOSIM R. BRUV,
baited remote underwater video; UVC, underwater visual census. Statisti-
cally significant comparisons are indicated by P-values
Location Distance (km) BRUV UVC
RP-value RP-value
AB, BH
A
87 0.25 ,0.0005 0.22 0.03
AB, PW 288 0.26 ,0.0005 0.33 ,0.005
AB, PE 306 0.49 ,0.0005 0.42 ,0.005
AB, CC 562 0.64 ,0.0005 0.79 ,0.0005
AB, CH 670 0.59 ,0.0005 0.89 ,0.0005
BH, PW
A
201 0.19 ,0.005 0.63 ,0.0005
BH, PE 219 0.42 ,0.0005 0.68 ,0.005
BH, CC 475 0.70 ,0.0005 0.98 ,0.005
BH, CH 583 0.68 ,0.0005 1.00 ,0.0005
PW, PE
A
18 0.15 0.02 0.40 ,0.005
PW, CC 274 0.30 ,0.005 0.96 ,0.0005
PW, CH 382 0.58 ,0.0005 0.98 ,0.0005
PE, CC
A
256 0.29 ,0.005 0.91 ,0.005
PE, CH 364 0.51 ,0.0005 0.96 ,0.0005
CC, CH
A
108 0.32 ,0.005 0.69 ,0.0005
A
Comparisons between neighbouring locations.
Faunal breaks in Victoria Marine and Freshwater Research 225
were intermediate between locations to the east and west. There
was also clear variation between the methods in their abilities to
measure differences between locations. With the exception of
pairwise comparisons between AB and the other locations, UVC
found more differences between locations than BRUV as shown
by higher UVC ANOSIM R-values (Fig. 4; Table 4).
Discussion
With a convergence zone and accompanying differences in sea
surface temperature and both historical and contemporary
habitat discontinuities, it is unsurprising that Victoria has been
identified as containing a biogeographic break for several taxa.
The exact location of the break differs by study: some have
identified Wilsons Promontory as the location of a disjunction
(O’Hara and Poore 2000), whereas others have located a
biogeographic break at Ninety Mile Beach (Hutchins 1987;
Kuiter 2000; Hidas et al. 2007; Gomon et al. 2008). In the
present research, data collected using UVC revealed the largest
difference in fish assemblage composition, measured by
ANOSIM R-values, between Cape Conran and the east coast of
Wilsons Promontory, in the vicinity of Ninety Mile Beach
(Fig. 4). Although not quite as large, the dissimilarity between
Cape Conran and Cape Howe was also notable. Neither
regression residuals (Fig. 4b) nor MDS plots (Fig. 2) indicated
the presence of a faunal break at Wilsons Promontory.
There was a fairly high level of species turnover associated
with Wilsons Promontory, although few species had ranges that
terminated on either of its coasts (Table 3). Rather than being a
discrete range boundary, Wilsons Promontory appears to act as a
transition zone in which species from different provinces
overlap. For example, the species pairs Parma microlepis and
P. victoriae and Girella elevata and G. zebra co-occurred at the
Promontory. P. microlepis and G. elevata are eastern species
and P. victoriae and G. zebra commonly occur along the south
coast (Kuiter 2000; Gomon et al. 2008). This suggests that there
are occasional opportunities for dispersal between the east and
west coasts of the Promontory but that they are sufficiently
rare to result in strong differences in abundance on either side of
the Promontory. The predominant eastward currents (Fig. 1)
suggest that the Promontory is an asymmetric, leaky boundary
analogous to Point Conception in California, USA (Wares
et al. 2001).
Dissimilarity as a function of distance
The regressions of coastline distance against dissimilarity
values for the UVC data were less straightforward than those for
BRUV data (Fig. 4a). The BRUV data exhibited a linear rela-
tionship between dissimilarity and coastline distance, with little
variation in dissimilarity values between pairs of neighbouring
locations. In contrast, the UVC data revealed that Apollo Bay
was more similar to all locations than would be suggested by
distance alone (Fig. 4b). Several species were observed in the
east region and at Apollo Bay, including Atypichthys strigatus,
Latridopsis forsteri,Meuschenia scaber and Sphyraena
novaehollandiae (Table 2). Some of these species, such as
A. strigatus and S. novaehollandiae are described in guidebooks
as primarily east or south-eastern species (Kuiter 2000; Edgar
2005; Gomon et al. 2008) and their presence at Apollo Bay may
indicate either that their range has expanded or that their ranges
were previously incorrectly described. Alternatively, the simi-
larity between Apollo Bay and the other locations could be
driven by how different Barwon Heads is to the other locations,
e.g. r¼1.00 for a pairwise comparison between Barwon Heads
and Cape Howe (Table 4). Barwon Heads is close to Port Philip
Bay, which is known to support a distinct fish fauna (Kuiter
2000; Gomon et al. 2008); some species that are very abundant
in the bay are rarely seen on the open coast, such as Trachinops
caudimaculatus (M. Colton, pers. obs.).
Methodological differences
Data collected by the two survey methods revealed different
patterns: the BRUV data exhibited a gradation in assemblage
Table 5. Mean density of species contributing to differences between locations
Contributions (%) of species observed by UVC and identified by SIMPER as driving differences between locations flanking the proposed biogeographic
breaks. Species listed cumulatively account for .50% of differences between locations (abbreviated as in Fig. 1) and are listed in order of contribution
Species CC PE % Species CH CC %
Caesioperca lepidoptera 0.62 0.13 6.9 Caesioperca lepidoptera 0.26 0.62 5.8
Caesioperca rasor 0.19 0.57 5.0 Trachurus novaezelandiae 0.43 0 5.0
Scorpis lineolata 0.33 0.34 4.3 Atypichthys strigatus 0.52 0.23 4.3
Notolabrus gymnogenis 0.28 0 3.5 Scorpis lineolata 0.26 0.33 4.0
Cheilodactylus spectabilis 0.30 0.03 3.5 Chromis hypsilepis 0.32 0 3.9
Ophthalmolepis lineolata 0.33 0.07 3.4 Pseudolabrus psittaculus 0.05 0.34 3.4
Cheilodactylus nigripes 0.07 0.33 3.3 Cheilodactylus fuscus 0.25 0 3.0
Atypichthys strigatus 0.23 0.21 3.3 Trachinops taeniatus 0.24 0 2.9
Enoplosus armatus 0.11 0.31 2.7 Notolabrus fucicola 0.10 0.27 2.7
Notolabrus fucicola 0.27 0.12 2.7 Parequula melbournensis 0.02 0.24 2.7
Parma microlepis 0.44 0.24 2.7 Pempheris multiradiata 0.31 0.28 2.7
Urolophus cruciatus 0.2 0 2.6 Pictilabrus laticlavius 0.16 0.32 2.4
Hypoplectrodes maccullochi 0.21 0 2.5 Caesioperca rasor 0.04 0.19 2.2
Scorpis aequipinnis 0.03 0.21 2.5 Urolophus cruciatus 0.03 0.2 2.2
Parequula melbournensis 0.24 0.07 2.5 Aplodactylus arctidens 0.02 0.18 2.1
Odax cyanomelas 0.21 0.17 2.0
226 Marine and Freshwater Research M. A. Colton and S. E. Swearer
composition in which locations that were more geographically
distant were less similar than those that were geographically
proximate, whereas the UVC data exhibited evidence of faunal
disjunctions. Several studies have identified differences
between UVC and BRUV (e.g. Willis and Babcock 2000;
Watson et al. 2005) and in other research conducted in the same
study area, we found that BRUV and UVC sampled different
components of the fish fauna (Colton and Swearer 2010).
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 100 200 300 400 500 600 700
ANOSIM R-values for pairwise tests between locations
Distance (km)
0.4
0.3
0.2
0.1
0.0
0.1
0.2
0.3
0.4
(a)
(b)
PW, PE
AB, BH
CC, CH
BH, PW
BH, PE
PE, CC
PW, CC
AB, PW
AB, PE
PE, CH
PW, CH
BH, CC
AB, CC
BH, CH
AB, CH
ANOSIM R-value residuals
Increasin
g
distance
**
*
*
*
More
similar
Less
similar
BRUV
UVC
BRUV
UVC
Fig. 4. (a) Linear regression of multivariate correlation coefficients, ANOSIM R, for pairwise comparisons between locations as
a function of coastline distance. Regression lines are dashed for baited remote underwater video (BRUV) and solid for underwater
visual census (UVC). Equations are y¼0.0009xþ0.135 for BRUV with R
2
¼0.76 and P,0.0005, and y¼0.001xþ0.4032 for
UVC with R
2
¼0.41and P¼0.01. (b) Regression residuals, with asterisks indicating pairs of neighbouring locations. Locations
are abbreviated as in Fig. 1.
Faunal breaks in Victoria Marine and Freshwater Research 227
Notably, UVC sampled higher abundance of territorial and site-
attached species, whereas BRUV recorded higher abundance of
mobile predators. If UVC is better at surveying sedentary
species and BRUV at surveying mobile species, we would
expect the BRUV data to show less difference between locations
than the UVC data. Indeed this is what we observed: compared
with UVC, BRUV was less capable of distinguishing between
locations.
Another possible explanation of the observed differences
between locations is inter-annual variation. Cape Conran and
Cape Howe were sampled in different years, as were the two
coasts of Wilsons Promontory. However, as most of the species
in this research are fairly sedentary as adults and have a life span
greater than one year (Kuiter 2000; Gomon et al. 2008), we think
that this is unlikely to offer a complete explanation. Certainly
the difference in assemblage composition between Cape Conran
and the east coast of Wilsons Promontory could not be explained
in this manner as both these locations were sampled between
March and May 2009. In addition, we found very little differ-
ence between the east and west coasts of Wilsons Promontory,
which were sampled in different years, further supporting our
conclusion that interannual differences cannot fully explain the
observed patterns.
Factors causing disjunctions
The UVC data showed strong evidence of a biogeographic
disjunction between the east coast of Wilsons Promontory and
Cape Conran (Fig. 4; Table 4). The co-occurrence in this region
of several factors known to influence both dispersal and
colonisation (i.e. converging currents, isotherms and habitat
discontinuity) makes it difficult to attribute this faunal break to a
single mechanism. Indeed, although any one of these factors
acting alone could influence fish distributions, it is more likely
that a combination of factors structures the fish assemblages of
this region, as was found for an intertidal gastropod (Waters
2008).
In this region, there is a large, predominantly sandy barrier
some 300 km long along Ninety Mile Beach (Fig. 1), between
the two locations which had the highest dissimilarity value for
neighbouring locations. Other studies have found that sandy
areas limit gene flow, a measure of connectivity, for rocky reef
fishes. For example, Bernardi (2000) found a major phylo-
genetic break between populations of Embiotoca jacksoni
separated by a sandy region and Riginos and Nachman (2001)
found that populations of a blennioid fish, Axoclinus nigricaudus,
separated by sand were more genetically distinct that those
separated by continuous rocky reef habitat. In this research, the
difference in fish assemblage structure between locations flank-
ing Ninety Mile Beach suggests that a sandy expanse may also
structure fish communities in south-eastern Australia. Recent
work in the vicinity of Ninety Mile Beach has revealed areas
of low-relief, ephemeral reef in the south, usually deeper than
15 m and at least one area of higher relief reef in the east
(D. Ierodiaconou, pers. comm.). The periodic presence of deeper
reef along Ninety Mile Beach could explain why this area is not a
barrier for some species but is for others. Further surveys are
required to ascertain which species are resident in this area.
In addition to having a break in habitat continuity, eastern
Victoria is a convergence site for several currents (Fig. 1). Flow
has been shown to influence larval dispersal (Booth et al. 2007)
despite larval behaviour (Leis and McCormick 2002). For
example, Gaylord and Gaines (2000) showed theoretically that
in areas with upstream larval supply, flow can lead to discrete
boundaries in species’ distributions even in the presence of
continuous habitat. In our research, we found evidence to
suggest that circulation patterns could drive distributions and
that the study region may be differentially permeable to east-
ward and westward dispersal (Table 3). For example, species
with southern Australian distributions were more able to over-
come the habitat disjunction at Ninety Mile Beach than were
species with eastern distributions. In addition, though only four
species had a range disjunction at Wilsons Promontory, 100% of
these species occur to the east of the Promontory. This suggests
that the predominant eastward flow in this region may play an
important role in regulating species’ distributions. These circu-
lation patterns may, to some extent, aid eastward dispersal of
individuals around the habitat-poor region of Ninety Mile
Beach. A similar mechanism was proposed to explain how the
larvae of Arripis trutta, a schooling species that moves consid-
erable distances offshore, released in Western Australia may
drift past the depauperate Great Australian Bight on eastward-
flowing currents to the west coast of Tasmania (Malcolm 1960;
Ridgway and Condie 2004).
Declines in abundance of species occurring on either side of
Ninety Mile Beach suggest that both westward dispersal of
eastern species and eastward dispersal of western species are
limited by this barrier. Although dispersal from the eastern
locations westward to Wilsons Promontory would involve
moving against predominant currents, it is certainly possible.
Malcolm (1960) recaptured in South Australia a tagged
Arripis trutta that had been released at the eastern end of Ninety
Mile Beach, meaning this individual travelled around Wilsons
Promontory and across Bass Strait. Westward movement
through this region might be facilitated by the presence of a
single area of shallow, rocky reef between Cape Conran and the
east coast of Wilsons Promontory located at Red Bluff which is
towards the eastern end of Ninety Mile Beach (Fig. 1). Hidas
et al. (2007) found that intertidal invertebrates that occurred on
either side of Ninety Mile Beach overlapped in their distribution
at Red Bluff, indicating that this site may be a stepping stone for
these species. Additional surveys at this location, as well as the
recently discovered ephemeral and deeper low-relief reefs may
indicate the same is true for fishes.
A third factor that could influence species’ distributions in
this region is a paleogeographical barrier. During glacial
periods, Victoria was connected to Tasmania via the Bassian
Isthmus in what is currently Bass Strait (Fig. 1). This paleogeo-
graphical barrier has left its signature on the genetic structure of
several taxa (Waters and Roy 2003; Waters et al. 2004) and on
the contemporary distributions of a few species. In this study,
several species had distributions that could be the relic of
vicariant speciation associated with the emergence of the
Bassian Isthmus and cooling temperatures, as has been
suggested for southern Australian cirrhitoids (Burridge 2000).
For example, some species pairs appeared to be separated into
eastern and western components, e.g. Parma microlepis and
P. victoriae and Scorpis aequipinnis and S. lineolata (Table 2).
Although the physical barrier is no longer present, competition
228 Marine and Freshwater Research M. A. Colton and S. E. Swearer
or some other mechanism, such as unfavourable environmental
conditions, could continue to regulate the distributions of
species like these. Other species have distributions that contain
large breaks in their centre, including the muraenid eel
Gymnothorax prasinus and the labrid Ophthalmolepis lineolata.
Range breaks like these may be indicative of colonisation failure
rather than a lack of dispersal ability. Information about these
species’ thermal tolerances and habitat requirements could
help us understand why they do not occur in central Victoria.
These disjunctions also suggest the potential for incipient
speciation; phylogenetic analyses would serve to further eluci-
date population connectivity for these and other species with
discontinuous ranges.
If contemporary barriers exist, then life history attributes
that influence dispersal and colonisation (e.g. pelagic larval
duration for sedentary reef-dwelling species) are likely to be
important and may explain differences among species in range
size. However, in this research, we found little evidence to
suggest a link between the potential for larval dispersal and
species’ distributions. For example, G. prasinus has lepto-
cephali, which are known to be highly dispersive, but was
observed only as far west as Cape Conran. In contrast, males
of the eastern pomacentrid P. microlepis guard demersal eggs
and larvae are estimated to be in the plankton for only a few
weeks (Curley and Gillings 2009), yet this species was observed
as far as the west coast of Wilsons Promontory. Support in the
literature for a general link between early life history and
distribution is equivocal. For example, Booth et al. (2007)
found that planktonic larval duration explained the southward
extent of tropical expatriates’ ranges in south-eastern Australia,
whereas Hidas et al. (2007) found no evidence linking dispersal
potential of intertidal invertebrates with the ability to circum-
vent a habitat barrier in Victoria. Perhaps the shorter dispersive
capacity of P. microlepis facilitates its occupation of the west
coast of Wilsons Promontory by preventing larvae from being
advected eastward by the predominant south-westerly wind-
driven currents. Additional data on the early life history of
these and other species are required to more fully explore
links between life history and dispersal in south-eastern
Australia.
Many of the differences in assemblage composition between
Wilsons Promontory and Cape Conran and between Cape
Conran and Cape Howe could be attributable to colonisation
failure: species are able to disperse to the region but cannot
survive once they arrive. The convergence of currents in this
region results in a temperature gradient of cooler waters in the
west to warmer waters in the east, with a rapid rise in tempera-
ture associated with a front in eastern Bass Strait (Gibbs 1991).
The majority of species with a break in the vicinity of Ninety
Mile Beach, i.e. between Wilsons Promontory and Cape
Conran, are east coast species that could be limited by their
ability to survive the cooler temperatures of southern Australia.
Juveniles of at least one east coast species, Chromis hypsilepis,
were observed at Cape Conran (M. Colton, pers. obs.), though
adults of this species were observed only at Cape Howe. The
presence of juveniles and lack of adults at Cape Conran suggests
that colonisation failure may be the limiting factor for this
species. It is likely that winter temperatures prevent C. hypsile-
pis from surviving, in a similar manner to tropical expatriates in
eastern Australia whose southern range limits are largely deter-
mined by overwinter survival (Figueira and Booth 2010).
Potential for future change
South-eastern Australia is expected to experience dramatic and
potentially rapid changes in currents and sea temperatures as a
result of global climate change (Figueira and Booth 2010;
Hobday and Lough 2011). One study (Figueira and Booth 2010)
suggests that sea surface temperatures have increased by
,1.58C over the last 130 years, which is already having mea-
surable effects on the fauna of this region (Last et al. 2010). For
example, the urchin Centrostephanus rodgersii has expanded its
range to and around Tasmania, an expansion that is associated
with strengthening of the East Australian Current (Ling et al.
2009) and numerous reef-dwelling fishes have displayed similar
range expansions and increases in abundance (Last et al. 2010).
In Victoria, strengthening of the EAC could result in warmer
water temperatures that could allow species like C. hypsilepis to
expand their range. Although some species’ ranges might
expand as a result of climate change, we might expect concomi-
tant range contractions of other species. For example,
M. australis is a primarily Tasmanian species that only reaches
the mainland in the vicinity of Bass Strait. As water tempera-
tures increase in Victoria, species such as M. australis may
decline in abundance in Victoria. Declines such as this could be
driven by any number of factors, including increased metabolic
demand associated with warmer waters or inter-specific
competition. Predicting how species will respond to climate
change requires an understanding of species’ distributions, such
as that provided by this research. The patterns of abundance and
distribution that we have quantified provide both a baseline
against which future changes may be measured and an under-
standing of the factors that structure populations in this region.
Acknowledgements
This research was funded by Natural Heritage Trust and Parks Victoria and
conducted under DSE permits numbers 10004231 and 10004876 and with
approval from the Animal Ethics Committee of the University of Melbourne.
Invaluable field assistance was provided by D. Chamberlain, J. Ford,
C. Jung, M. LeFeuvre, M. Lindsay and Parks Victoria staff. Comments from
three anonymous reviewers and the Associate Editor helped to improve this
paper. During this research, M. C. received support from an Australian
Postgraduate Award and a Helen McPherson-Smith Scholarship.
References
Bernardi, G. (2000). Barriers to gene flow in Embiotoca jacksoni, a marine
fish lacking a pelagic larval stage. Evolution 54, 226–237.
Booth, D. J., Figueira, W. F., Gregson, M. A., Brown, L., and Beretta, G.
(2007). Occurrence of tropical fishes in temperate southeastern Austra-
lia: role of the East Australian Current. Estuarine, Coastal and Shelf
Science 72, 102–114. doi:10.1016/J.ECSS.2006.10.003
Burridge, C. P. (2000). Biogeographic history of geminate cirrhitoids
(Perciformes: Cirrhitoidea) with east–west allopatric distributions
across southern Australia, based on molecular data. Global Ecology
and Biogeography 9, 517–525. doi:10.1046/J.1365-2699.2000.00204.X
Clarke, K. R., and Gorley, R. N. (2006). ‘PRIMER v6: User Manual/
Tutorial.’ (Primer-E Ltd.: Plymouth, UK.)
Clarke, K. R., and Warwick, R. M. (2001). ‘Change in Marine Communities:
an Approach to Statistical Analysis and Interpretation.’ (Primer-E Ltd.:
Plymouth, UK.)
Faunal breaks in Victoria Marine and Freshwater Research 229
Colton, M. A. (2011). Patterns in the distribution and abundance of reef
fishes in south-eastern Australia. Ph.D. Thesis, University of Melbourne.
Colton, M. A., and Swearer, S. E. (2010). A comparison of two survey
methods: differences between underwater visual census and baited
remote underwater video. Marine Ecology Progress Series 400,
19–36. doi:10.3354/MEPS08377
Curley, B. G., and Gillings, M. R. (2009). Population connectivity in the
temperate damselfish Parma microlepis: analyses of genetic structure
across multiple spatial scales. Marine Biology 156, 381–393.
doi:10.1007/S00227-008-1090-0
Dawson, M. N. (2005). Incipient speciation of Catostylus mosaicus
(Scyphozoa, Rhizostomeae, Catostylidae), comparative phylogeogra-
phy and biogeography in south-east Australia. Journal of Biogeography
32, 515–533. doi:10.1111/J.1365-2699.2004.01193.X
Edgar, G. J. (2005). ‘Australian Marine Life: the Plants and Animals of
Temperate Waters.’ (Reed New Holland: Sydney.)
Eschmeyer, W. N., and Fricke, R. (2009). Catalog of fishes. Available
at http://research.calacademy.org/ichthyology/catalog/fishcatmain.asp
[Accessed 9 September 2009].
Fandry, C. B. (1983). Model for the 3-dimensional structure of wind-driven
and tidal circulation in Bass Strait. Australian Journal of Marine and
Freshwater Research 34, 121–141. doi:10.1071/MF9830121
Figueira, W. F., and Booth, D. J. (2010). Increasing ocean
temperatures allow tropical fishes to survive overwinter in temperate
waters. Global Change Biology 16, 506–516. doi:10.1111/J.1365-2486.
2009.01934.X
Gaylord, B., and Gaines, S. D. (2000). Temperature or transport? Range
limits in marine species mediated solely by flow. American Naturalist
155, 769–789. doi:10.1086/303357
Gibbs, C. F. (1991). Oceanography of Bass Strait – implication for the food
supply of Little Penguins Eudyptula minor. Emu 91, 395–401.
doi:10.1071/MU9910395
Gomon, M. F., Bray, D., and Kuiter, R. (2008). ‘Fishes of Australia’s
Southern Coast.’ (Reed New Holland: Sydney.)
Hidas, E. Z., Costa, T. L., Ayre, D. J., and Minchinton, T. E. (2007). Is the
species composition of rocky intertidal invertebrates across a biogeo-
graphic barrier in south-eastern Australia related to their potential for
dispersal? Marine and Freshwater Research 58, 835–842. doi:10.1071/
MF06235
Hobday, A. J., and Lough, J. M. (2011). Projected climate change in
Australian marine and freshwater environments. Marine and Freshwater
Research 62, 1000–1014. doi:10.1071/MF10302
Horn, M. H., and Allen, L. G. (1978). Distributional analysis of California
coastal marine fishes. Journal of Biogeography 5, 23–42. doi:10.2307/
3038105
Hough, D., and Mahon, G. (1994). Biophysical classification of Victoria’s
marine waters. In ‘Towards a Marine Regionalisation for Australia.
Ocean Rescue 2000 Workshop Series No. 1. Session 2’. (Ed.
J. Muldoon.) (Great Barrier Reef Marine Park Authority: Sydney, NSW)
Hutchins, J. B. (1987). Description of a new plesiopid fish from south-
western Australia with a discussion of the zoogeography of Paraple-
siops. Records of the Western Australian Museum 13, 231–240.
Kuiter, R. H. (2000). ‘Coastal Fishes of South-eastern Australia.’ (Gary
Allen Pty Ltd: Sydney.)
Lambeck, K., and Chappell, J. (2001). Sea level change through the last
glacial cycle. Science 292, 679–686. doi:10.1126/SCIENCE.1059549
Last, P. R., White, W. T., Gledhill, D. C., Hobday, A. J., Brown, R., Edgar,
G. J., and Pecl, G. (2010). Long-term shifts in abundance and distribution
of a temperate fish fauna: a response to climate change and fishing
practices. Global Ecology and Biogeography 20, 58–72.
Leis, J. M., and McCormick, M. I. (2002). The biology, behavior, and
ecology of the pelagic, larval stage of coral reef fishes. In ‘Coral Reef
Fishes’. (Ed. P. F. Sale.) pp. 171–199. (Academic Press: San Diego, CA.)
Ling, S. D., Johnson, C. R., Ridgway, K., Hobday, A. J., and Haddon, M.
(2009). Climate-driven range extension of a sea urchin: inferring future
trends by analysis of recent population dynamics. Global Change
Biology 15, 719–731. doi:10.1111/J.1365-2486.2008.01734.X
Lourie, S. A., and Vincent, A. C. J. (2004). Using biogeography to help set
priorities in marine conservation. Conservation Biology 18, 1004–1020.
doi:10.1111/J.1523-1739.2004.00137.X
Lyne, V., Last, P. R., Gomon, M. F., Scott, R., Long, S., Phillips, A.,
McArdle, B., Peters, D., Pigot, S., and Kailola, P. (1996). ‘Interim
Marine Bioregionalisation for Australia: Towards a National System of
Marine Protected Areas.’ (CSIRO Division of Fisheries and Division of
Oceanography.)
Malcolm, W. B. (1960). Area of distribution, and movement of the western
subspecies of the Australian ‘salmon’, Arripis trutta esper Whitley.
Marine and Freshwater Research 11, 282–325. doi:10.1071/
MF9600282
Marshall, D. J., Monro, K., Bode, M., Keough, M. J., and Swearer, S. (2010).
Phenotype-environment mismatches reduce connectivity in the sea.
Ecology Letters 13, 128–140.
Murray, S. N., and Littler, M. M. (1981). Biogeographical analysis of
intertidal macrophyte floras of southern California. Journal of Biogeog-
raphy 8, 339–351. doi:10.2307/2844755
Myers, A. A. (1997). Biogeographic barriers and the development of marine
biodiversity. Estuarine, Coastal and Shelf Science 44, 241–248.
doi:10.1006/ECSS.1996.0216
O’Hara, T. D., and Poore, G. C. B. (2000). Patterns of distribution for
southern Australian marine echinoderms and decapods. Journal of
Biogeography 27, 1321–1335. doi:10.1046/J.1365-2699.2000.00499.X
Pelc, R. A., Warner, R. R., and Gaines, S. D. (2009). Geographical patterns
of genetic structure in marine species with contrasting life histories.
Journal of Biogeography 36, 1881–1890. doi:10.1111/J.1365-2699.
2009.02138.X
Pondella, D. J., Gintert, B. E., Cobb, J. R., and Allen, L. G. (2005).
Biogeography of the nearshore rocky-reef fishes at the southern and
Baja California islands. Journal of Biogeography 32, 187–201.
doi:10.1111/J.1365-2699.2004.01180.X
Ridgway, K. R., and Condie, S. A. (2004). The 5500-km-long boundary flow
off western and southern Australia. Journal of Geophysical Research
109, C04017. doi:10.1029/2003JC001921
Ridgway, K. R., and Dunn, J. R. (2003). Mesoscale structure of the mean
East Australian Current System and its relationship with topography.
Progress in Oceanography 56, 189–222. doi:10.1016/S0079-6611(03)
00004-1
Riginos, C., and Nachman, M. W. (2001). Population subdivision in marine
environments: the contributions of biogeography, geographical distance
and discontinuous habitat to genetic differentiation in a blennioid fish,
Axoclinus nigricaudus. Molecular Ecology 10, 1439–1453. doi:10.1046/
J.1365-294X.2001.01294.X
Sandery, P. A., and Kampf, J. (2005). Winter-spring flushing of Bass Strait,
south-eastern Australia: a numerical modelling study. Estuarine, Coast-
al and Shelf Science 63, 23–31. doi:10.1016/J.ECSS.2004.10.009
Sexton, J. P., McIntyre, P. J., Angert, A. L., and Rice, K. J. (2009). Evolution
and ecology of species range limits. Annual Review of Ecology Evolution
and Systematics 40, 415–436. doi:10.1146/ANNUREV.ECOLSYS.
110308.120317
Shima, J. S., and Swearer, S. E. (2010). The legacy of dispersal: larval
experience shapes persistence later in the life of a reef fish. Journal of
Animal Ecology 79, 1308–1314.
Wares, J. P., Gaines, S. D., and Cunningham, C. W. (2001). A comparative
study of asymmetric migration events across a marine biogeographic
boundary. Evolution 55, 295–306.
Waters, J. M. (2008). Marine biogeographical disjunction in temperate
Australia: historical landbridge, contemporary currents, or both?
230 Marine and Freshwater Research M. A. Colton and S. E. Swearer
Diversity & Distributions 14, 692–700. doi:10.1111/J.1472-4642.2008.
00481.X
Waters, J. M., and Roy, M. S. (2003). Marine biogeography of southern
Australia: phylogeographical structure in a temperate sea-star. Journal
of Biogeography 30, 1787–1796. doi:10.1046/J.0305-0270.2003.
00978.X
Waters, J. M., O’Loughlin, P. M., and Roy, M. S. (2004). Cladogenesis in a
starfish species complex from southern Australia: evidence for vicariant
speciation? Molecular Phylogenetics and Evolution 32, 236–245.
doi:10.1016/J.YMPEV.2003.11.014
Waters, J. M., King, T. M., O’Loughlin, P. M., and Spencer, H. G. (2005).
Phylogeographical disjunction in abundant high-dispersal littoral gas-
tropods. Molecular Ecology 14, 2789–2802. doi:10.1111/J.1365-294X.
2005.02635.X
Watson, D. L., Harvey, E. S., Anderson, M. J., and Kendrick, G. A. (2005).
A comparison of temperate reef fish assemblages recorded by three
underwater stereo-video techniques. Marine Biology 148, 415–425.
doi:10.1007/S00227-005-0090-6
Wethey, D. S. (2002). Biogeography, competition, and microclimate: the
barnacle Chthamalus fragilis in New England. Integrative and Compar-
ative Biology 42, 872–880. doi:10.1093/ICB/42.4.872
Whitley, G. (1932). Marine zoogeographical regions of Australia. The
Australian Naturalist 8, 166–167.
Willis, T. J., and Babcock, R. C. (2000). A baited underwater video system
for the determination of relative density of carnivorous reef fish. Marine
and Freshwater Research 51, 755–763. doi:10.1071/MF00010
www.publish.csiro.au/journals/mfr
Faunal breaks in Victoria Marine and Freshwater Research 231
10.1071/MF10322_AC
© CSIRO 2012
Supplementary Material: Marine and Freshwater Research, 2012, 63(3), 218–231
Supplementary Material
Table S1. Species’ abundances by location and method
Mean abundance measured by MaxN using BRUV (baited remote underwater video), and mean density (m-2) by UVC (underwater visual
census) (see Methods for more details). Locations are abbreviated as in Fig. 1
BRUVUVC
SpeciesABBHPWPECCCHABBHPWPECCCH
Acanthaluteresvittiger0.0455 0.5294 0.0952 0.4167 0.1000 0.20830.0010 0.0020 0.0093 0.0006 00.0093
Acanthistiusocellatus0 0 0 0 0.1000 0.3750000000.0004
Achoerodusviridis0 0 0 0.25 0.5000 0.20830 0 0 0 0.0069 0.0018
Allomycteruspilatus0 0 0 0.0833 0 0
Aplodactylusarctidens0.1364 0.0588 0.1905 0.4167 0.1000 0.16670.0015 0.0001 0.0021 0.0005 0.0049 0.0001
Aracanaaurita0.0909 00.0476 0000.0008 00.0013 0.0005 0 0
Aracanaornata0 0 0 0.5000 0 00 0 0.0001 0.0003 0 0
Atypichthysstrigatus0 0 2.1905 2.6667 0.6000 23.91670.0002 00.0214 0.0214 0.0451 0.0941
Aulopuspurpurissatus0.0455 0.0588 0 0 0 00.0001 0 0 0.0002 0 0
Caesiopercalepidoptera0 0 0.0476 0.4167 10.4000 10.04170 0 0.0001 0.0189 0.5393 0.0395
Caesiopercarasor0.0455 1.8824 4.5714 3.8333 2.7000 0.12500.0123 0.0008 0.0595 0.1126 0.0066 0.0015
Cephaloscylliumlaticeps0.4091 0.0588 0.2381 04.9000 1.08330.0000 0.0001 0.0007 0.0001 0.0023 0.0009
Cheilodactylusfuscus0 0 0 0 0 0.0417000000.0052
Cheilodactylusnigripes0.3636 0.5882 0.5238 0.5833 0.5000 00.0048 0.0030 0.0031 0.0117 0.0007 0.0001
Cheilodactylusspectabilis0.0455 00.1429 0.0833 0.2000 0.45830.0000 0.0001 0.0003 0.0001 0.0139 0.0054
Chironemusmarmoratus0 0 0 0 0 0.0417000000.0026
Chromishypsilepis0 0 0 0 0 4.3333000000.0272
Chrysophrysauratus4.2727 0.9412 0.2381 0.2500 03.29170.0001 0 0 0 0 0.0022
Corissandageri 000000.0002
Crinoduslophodon0 0 0 0 0.3000 0.04170 0 0 0 0.0021 0.0033
Dactylophoranigricans0.0909 0.0588 00.2500 0 00.0003 00.0004 0 0 0
Dasyatisbrevicaudata0.1818 0.3529 0.0476 0 0 0.0417
Dicotylichthyspunctulatus 0 0 0 0.0002 0.0002 0.0002
Dinolesteslewini0.7727 0.1765 1.6667 0.7500 1.9000 0.75000.0068 0.0026 0.0081 0.0019 0.0006 0.0068
Diodonnicthemerus 0.0008 0.0003 0.0004 0.0009 0.0005 0.0005
Dotolabrusaurantiacus0.0455 00.0476 0.1667 00.04170.0001 0.0004 0.0001 0.0015 0.0002 0
Eeyoriushutchinsi0.0455 0 0 0 0.1000 0
Enoplosusarmatus0.1818 0.8235 0.3810 0.9167 0.6000 0.08330.0012 0.0015 0.0062 0.0110 0.0013 0.0131
Eubalichthysbucephalus0 0 0 0 0 0.2500000000.0006
Eubalichthysgunnii0 0 0 0.0833 0 00 0 0 0.0005 0 0
Eubalichthysmosaicus00.0588 0 0 0.4000 0.33330 0 0 0.0002 0.0002 0
Eupetrichthysangustipes0 0 0.0476 00.1000 000.0003 0.0009 0.0006 0.0017 0.0035
Girellaelevata0 0 0 0 0.1000 00 0 0.0001 00.0027 0
Girellazebra0.6364 0.0588 0.5238 0.7500 1.3000 0.08330.0009 0.0059 0.0056 0.0016 0.0022 0.0005
Gymnothoraxprasinus0 0 0 0 0.3000 1.2500000000.0002
Halettasemifasciata0.0455 0 0 0.1667 0 00.0000 0 0 0 0 0
Heterodontusportusjacksoni0.3636 0.1176 0.5238 0.0833 0.3000 0.3750000000.0016
Hypoplectrodesmaccullochi0 0 0 0 0.2000 0.58330 0 0 0 0.0081 0.0039
Hypoplectrodesnigroruber 0 0 0 0.0010 0.0003 0
Latridopsisforsteri0.0909 00.0476 0.0833 0.2000 0.12500.0004 00.0005 0.0003 00.0005
Lepidotriglavanessa 0.0001 0 0 0 0 0
Lotellarhacina0 0 0 0 0.1000 00 0 0 0 0.0013 0.0002
Meuscheniaaustralis0 0 0.0476 00000.0001 0.0003 0 0 0
Meuscheniaflavolineata00.6471 0.0952 0.2500 0.2000 00.0004 0.0055 0.0002 0.0005 00.0002
Meuscheniafreycineti0.8636 0.9412 0.3333 0.7500 1.3000 1.58330.0002 0.0002 0.0012 0.0004 00.0009
Meuscheniagalii00.3529 0 0 0 00.0000 0.0003 0 0 0 0
Meuscheniahippocrepis2.7273 1.5882 0 0 0.1000 00.0090 0.0032 0.0001 0 0 0
Meuscheniascaber0 0 0 0 2.3000 1.00000.0005 0 0 0 0.0019 0.0006
Meuscheniavenusta0 0 0 0 0.1000 00 0 0 0 0.0002 0.0001
Mustelusantarcticus0 0 0 0.0833 0.1000 0.1667
Myliobatisaustralis0.5000 0.1765 0.2857 0.0833 0.1000 0.04170.0002 0 0 0 0 0
Nemadactylusdouglasii0 0 0 0.1667 1.7000 0.41670 0 0 0 0.0042 0.0019
Nemadactylusmacropterus0 0 0 0 0 0.08330 0 0 0.0001 0 0
Neoodaxbalteatus0 0 0 0.0833 0 00.0002 0 0 0.0010 0.0003 0
Notolabrusfucicola2.5455 0.1176 0.7619 0.1667 1.0000 0.37500.0071 0.0004 0.0087 0.0015 0.0138 0.0024
Notolabrusgymnogenis0 0 0 0 0.2000 0.291700.0001 0 0 0.0071 0.0069
Notolabrustetricus4.5455 7.0000 5.5714 9.5000 5.6000 1.95830.0093 0.0171 0.0397 0.0380 0.0572 0.0187
Odaxacroptilus0.0455 0.0588 0.0476 0.2500 0 00.0001 00.0006 0.0012 00.0002
Odaxcyanomelas0.4091 0.8235 0.5238 0.6667 0.5000 0.45830.0048 0.0030 0.0123 0.0027 0.0015 0.0090
Ophthalmolepislineolata0 0 0 0.1667 4.9000 4.83330 0 0 0.0009 0.0148 0.0206
Optivusagastos 0 0 0 0.0002 00.0003
Parequulamelbournensis0.4545 00.1429 0.5833 2.6000 0.29170 0 0.0068 0.0010 0.0082 0.0002
Parmamicrolepis0 0 0 0.1667 1.5000 1.37500 0 0.0002 0.0041 0.0474 0.0246
Parmavictoriae0.1364 0.4706 0.2857 0.1667 0 00.0005 0.0039 0.0042 0.0034 0 0
Pempheriscompressa 0 0 0.0005 0 0 0.015
Pempherismultiradiata00.1765 0 0 0 00.0072 0.0146 0.0086 0.0059 0.0264 0.0249
Pentaceropsisrecurvirostris0 0 0.1429 00.2000 0.04170.0002 0.0002 0.0001 0.0005 0.0002 0.0001
Pictilabruslaticlavius0.5455 1.1176 0.4286 1.1667 0.9000 0.20830.0013 0.0018 0.0029 0.0086 0.0118 0.0069
Platycephalusbassensis0.1818 00.2857 0.4167 0.1000 0
Pseudolabruspsittaculus0.3182 0.0588 0.1429 0.0833 3.2000 0.12500.0003 00.0013 0.0012 0.0201 0.0005
Pseudophycisbachus 0 0 0 0.0005 0 0
Pseudophycisbarbata0.3182 00.1905 0.4167 0 0
Rexeasolandri0 0 0 0.4167 0 0
Scobinichthysgranulatus0 0 0 0.3333 0 00 0 0.0001 00.0002 0
Scorpisaequipinnis0.1818 1.7059 0.0476 0.9167 0 00.0037 0.0041 0.0125 0.0073 0.0002 0
Scorpislineolata00.8235 0.5714 3.6667 0.2000 9.041700.0008 0.0010 0.0352 0.0969 0.0230
Seriolalalandi0 0 0 0 0.1000 0.1667
Sillaginodespunctatus0.9091 0.2941 0.6667 3.0833 0 00 0 0.0031 0 0 0
Siphonognathusbeddomei 0 0 0.0016 0 0 0
Sphyraenanovaehollandiae0.1364 00.1429 0.2500 1.4000 0.2083000000.0001
Suezichthysaylingi 000000.0004
Tetractenosglaber0.0455 0.0588 0.1429 0 0 0.08330.0001 00.0001 0 0 0
Tilodonsexfasciatum00.1765 0.0952 0.0833 0 00.0005 0.0006 0.0003 0.0007 0 0
Trachinopscaudimaculatus02.2941 0 0 0 000.0044 00.0006 0 0
Trachinopstaeniatus 000000.0255
Trachurusdeclivis 0 0 0 0.0098 0.0436 0
Trachurusnovaezelandiae0.1364 5.6471 06.4167 037.50000 0 0.0002 0 0 0.1297
Trygonorrhinafasciata0.2273 00.1905 0000.0001 0 0 0 0 0
Trygonorrhinasp.A0.0455 0 0 0 0 0.0417
Urolophuscruciatus0 0 0 0 0.4000 00 0 0 0 0.0019 0.0003
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The relationship between metapopulation stability and connectivity has long been investigated in ecology, however, most of these studies are focused on theoretical species and habitat networks, having limited ability to capture the complexity of real‐world metapopulations. Network analysis became more important in modeling connectivity, but it is still uncertain which network metrics are reliable predictors of persistence. Here we quantify the impact of connectivity and larval life history on marine metapopulation persistence across the complex seascape of southeast Australia. Our work coupled network‐based approaches and eigenanalysis to efficiently estimate metapopulation‐wide persistence and the subpopulation contributions. Larval dispersal models were used to quantify species‐specific metapopulation connectivity for five important fisheries species, each summarized as a migration matrix. Eigenanalysis helped to reveal metapopulation persistence and determine the importance of node‐level network properties. Across metapopulations, the number of local outgoing connections was found to have the largest impact on metapopulation persistence, implying these hub subpopulations may be the most influential in real‐world metapopulations. Results also suggest the length of the pre‐competency period may be the most influential parameter on metapopulation persistence. Finally, we identified two major hot spots of local connectivity in southeast Australia, each contributing strongly to multispecies persistence. Managers and ecologists would benefit by employing similar approaches in making more efficient and more ecologically informed decisions and focusing more on local connectivity patterns and larval competency characteristics to better understand and protect real‐world metapopulation persistence. Practically this could mean developing more marine protected areas at shorter distances and supporting collaborative research into the early life histories of the species of interest.
... Since complete submergence of the Isthmus c. 14 000 years ago (Lambeck and Chappell 2001), a combination of demersal spawning and contemporary oceanographic features may have sustained these patterns of historical vicariance. The complex convergence of the East Australian Current (EAC) and South Australian Boundary Current has been shown to limit colonisation and dispersal in other marine species separated historically by the Bassian Isthmus (Waters 2008;Colton and Swearer 2012). Both H. melanochir and H. australis are demersal spawners, and their substrate-adhesive eggs and well developed larvae may increase the likelihood of early lifestage retention within seagrass habitats (Jones et al. 2002;Stewart et al. 2005), thus likely limiting passive dispersal by coastal currents. ...
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Context Species classification disputes can be resolved using integrative taxonomy, which involves the use of both phenotypic and genetic information to determine species boundaries. Aims Our aim was to clarify species boundaries of two commercially important cryptic species of halfbeak (Hemiramphidae), whose distributions overlap in south-eastern Australia, and assist fisheries management. Methods We applied an integrative taxonomic approach to clarify species boundaries and assist fisheries management. Key results Mitochondrial DNA and morphological data exhibited significant differences between the two species. The low level of mitochondrial DNA divergence, coupled with the lack of difference in the nuclear DNA, suggests that these species diverged relatively recently (c. 500 000 years ago) when compared with other species within the Hyporhamphus genus (>2.4 million years ago). Genetic differences between the species were accompanied by differences in modal gill raker counts, mean upper-jaw and preorbital length, and otolith shape. Conclusions On the basis of these genetic and morphological differences, as well as the lack of morphological intergradation between species along the overlapping boundaries of their geographical distributions, we propose that Hyporhamphus australis and Hyporhamphus melanochir remain valid species. Implications This study has illustrated the need for an integrative taxonomic approach when assessing species boundaries and has provided a methodological framework for studying other cryptic fish species in a management context.
... The trophic structure of reef fish communities varies latitudinally from herbivores and omnivores at subtropical latitudes (~30 • S), zooplanktivores at ~ 35 • S, to benthic invertivores at higher latitudes (~40 • S), and latitudinal and seasonal patterns are observed in biomass (Holland et al., 2020). Likewise, eastward and westward dispersal of larval fishes and resulting fish species distributions across southeast Australia's Bass Strait is likely driven by the circulation patterns from the convergence of multiple ocean currents (Colton and Swearer, 2011). These findings are important for predicting climate change impacts on fishes over the latitudinal extent of southeast Australia, given the observed tropicalization in temperate reef fish distributions (Vergés et al., 2016) that is predicted with a warming (Figueira and Booth, 2010) and intensified EAC (Vergés et al., 2014). ...
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... This region significance is well known and includes several ecological features, which define the structure of the coastal communities. Eastern Victoria was identified as potential biogeographic break for many taxa often associated with limits in species' ranges and changes in community assemblages (Colton and Swearer, 2012). Habitat patches in northern Tasmania may also be essential for ensuring connectivity between Tasmania and Victoria coasts. ...
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... Determining the spatial structure of assemblages can support and inform bioregional and EBFM for any area worldwide (Browman & Stergiou 2004). Bioregions can also aid in conserving entire ecosystems and monitoring distributional changes and extinctions, particularly of small-range endemic species (Briggs & Bowen 2012, Colton & Swearer 2012. Both ecological and fisheries bioregionalisation of any region should accurately represent the current distribution of species that inhabit the area. ...
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Bioregional categorisation of the Australian marine environment is essential to conserve and manage entire ecosystems, including the biota and associated habitats. It is important that these regions are optimally positioned to effectively plan for the protection of distinct assemblages. Recent climatic variation and changes to the marine environment in Southwest Australia (SWA) have resulted in shifts in species ranges and changes to the composition of marine assemblages. The goal of this study was to determine if the current bioregionalisation of SWA accurately represents the present distribution of shallow-water reef fishes across 2000 km of its subtropical and temperate coastline. Data was collected in 2015 using diver-operated underwater stereo-video surveys from 7 regions between Port Gregory (north of Geraldton) to the east of Esperance. This study indicated that (1) the shallow-water reef fish of SWA formed 4 distinct assemblages along the coast: one Midwestern, one Central and 2 Southern Assemblages; (2) differences between these fish assemblages were primarily driven by sea surface temperature, Ecklonia radiata cover, non- E. radiata (canopy) cover, understorey algae cover, reef type and reef height; and (3) each of the 4 assemblages were characterised by a high number of short-range Australian and Western Australian endemic species. The findings from this study suggest that 4, rather than the existing 3 bioregions would more effectively capture the shallow-water reef fish assemblage patterns, with boundaries having shifted southwards likely associated with ocean warming.
... All surveys were conducted between 3.7 and 28 m depth. As these sites have similar species assemblages (Colton & Swearer 2012), and our sampling was conducted over a short temporal window at each site (Table S1), we combined surveys across all sites and sampling dates to look at overall fish-habitat associations. ...
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Understanding how animals interact with their environment is a fundamental ecological question with important implications for conservation and management. The relationships between animals and their habitat, however, can be scale‐dependent. If ecologists work at suboptimal spatial scales, they will gain an incomplete picture of how animals respond to the landscape. Identifying the scale at which animal–landscape relationships are strongest (the “scale of effect”) will improve our ability to better plan management and conservation activities. Several recent studies have greatly enhanced our knowledge about the scale of effect, and the potential drivers of interspecific variability, in particular life‐history traits. However, while many marine systems are inherently multiscalar, research into the scale of effect has been mainly focussed on terrestrial taxa. As the scales of observation in fish–habitat association studies are often selected based on convention rather than biological reasoning, they may provide an incomplete picture of the scales where these associations are strongest. We examined fish–habitat associations across four nested spatial scales in a temperate reef system to ask: (a) at what scale are fish–habitat associations the strongest, (b) are habitat elements consistently important across scales, and (c) do scale‐dependent fish–habitat associations vary in relation to either body size, geographic range size or trophic level? We found that: (a) the strongest fish–habitat associations were observed when these relationships were examined at considerably larger spatial scales than usually investigated; (b) the importance of environmental predictors varied across spatial scales, indicating that conclusions about the importance of habitat elements will depend on the scales at which studies are undertaken; and (c) scale‐dependent fish–habitat associations were consistent across all life‐history traits. Our results highlight the importance of considering how animals relate to their environment and suggest the small scales often chosen to examine fish–habitat associations are likely to be suboptimal. Developing a more mechanistic understanding of animal–habitat associations will greatly aid in predicting and managing responses to future anthropogenic disturbances.
... For instance, there is an eastward flow through Bass Strait and complex seasonal eddy systems that might act as both barriers and traps for larval dispersal, impacting the westward range extension of C. rodgersii.Wilsons Promontory represents a geographic barrier along the neritic zone of the coast of Victoria, influencing ocean currents through Bass Strait. In addition, the convergence of waters from two boundary currents, the East Australian Current and South Australian Current, generates more complex conditions across the Strait(Colton & Swearer, 2012;Gibbs, 1991). Nevertheless, C. rodgersii individuals have been detected over 500 km to the west of their known geographic range in Victoria, demonstrating the potential threat of founder populations, despite known barriers, and the potential threat of establishment as more suitable warmer temperatures arise in the future. ...
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Characterising adaptive genetic divergence among conspecific populations is often achieved by studying genetic variation across defined environmental gradients. In marine systems this is challenging due to a paucity of information on habitat heterogeneity at local and regional scales and a dependency on sampling regimes that are typically limited to broad longitudinal and latitudinal environmental gradients. As a result, the spatial scales at which selection processes operate and the environmental factors that contribute to genetic adaptation in marine systems are likely to be unclear. In this study we explore patterns of adaptive genetic structuring in a commercially‐ harvested abalone species (Haliotis rubra) from south‐eastern Australia, using a panel of genome‐wide SNP markers (5,239 SNPs), and a sampling regime informed by marine LiDAR bathymetric imagery and 20‐year hindcasted oceanographic models. Despite a lack of overall genetic structure across the sampling distribution, significant genotype associations with heterogeneous habitat features were observed at local and regional spatial scales, including associations with wave energy, ocean current, sea surface temperature, and geology. These findings provide insights into the potential resilience of the species to changing marine climates and the role of migration and selection on recruitment processes, with implications for conservation and fisheries management. This study points to the spatial scales at which selection processes operate in marine systems and highlights the benefits of geospatially‐informed sampling regimes for overcoming limitations associated with marine population genomic research. This article is protected by copyright. All rights reserved.
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