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Global Ecology and Biogeography, (Global Ecol. Biogeogr.) (2011) 20, 58–72 RESEARCH PA P E R Long-term shifts in abundance and distribution of a temperate fish fauna: a response to climate change and fishing practices geb_575 58..72 Peter R. Last1,2*, William T. White1,2, Daniel C. Gledhill1,2, Alistair J. Hobday1,2, Rebecca Brown3, Graham J. Edgar3 and Gretta Pecl3 1 Climate Adaptation Flagship, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart TAS 7001, Australia, 2Wealth from Oceans Flagship, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart TAS 7001, Australia, 3Tasmanian Aquaculture and Fisheries Institute, Private Bag 49, Hobart TAS 7001, Australia A B S T R AC T Aim South-eastern Australia is a climate change hotspot with well-documented recent changes in its physical marine environment. The impact on and temporal responses of the biota to change are less well understood, but appear to be due to influences of climate, as well as the non-climate related past and continuing human impacts. We attempt to resolve the agents of change by examining major temporal and distributional shifts in the fish fauna and making a tentative attribution of causal factors. Location Temperate seas of south-eastern Australia. Methods Mixed data sources synthesized from published accounts, scientific surveys, spearfishing and angling competitions, commercial catches and underwater photographic records, from the ‘late 1800s’ to the ‘present’, were examined to determine shifts in coastal fish distributions. Results Forty-five species, representing 27 families (about 30% of the inshore fish families occurring in the region), exhibited major distributional shifts thought to be climate related. These are distributed across the following categories: species previously rare or unlisted (12), with expanded ranges (23) and/or abundance increases (30), expanded populations in south-eastern Tasmania (16) and extralimital vagrants (4). Another 9 species, representing 7 families, experienced longerterm changes (since the 1800s) probably due to anthropogenic factors, such as habitat alteration and fishing pressure: species now extinct locally (3), recovering (3), threatened (2) or with remnant populations (1). One species is a temporary resident periodically recruited from New Zealand. Of fishes exhibiting an obvious poleward movement, most are reef dwellers from three Australian biogeographic categories: widespread southern, western warm temperate (Flindersian) or eastern warm temperate (Peronian) species. Main conclusions Some of the region’s largest predatory reef fishes have become extinct in Tasmanian seas since the ‘late 1800s’, most likely as a result of poor fishing practices. In more recent times, there have been major changes in the distribution patterns of Tasmanian fishes that correspond to dramatic warming observed in the local marine environment. *Correspondence: Peter Last, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart TAS 7001, Australia. E-mail: [email protected] 58 Keywords Climate change, fishing, south-eastern Australia, spatial shift, Tasmania, temperate fishes, temporal shift. DOI: 10.1111/j.1466-8238.2010.00575.x © 2010 Blackwell Publishing Ltd www.blackwellpublishing.com/geb Long-term shifts in a temperate fish fauna INTR O D U C TI O N Changes in faunal assemblages over time have been recorded in many marine communities and are often linked to anthropogenic impacts, such as fishing (e.g. Jackson et al., 2001), pollution (e.g. Schiel et al., 2004), invasive species (e.g. Currie & Parry, 1999) and climate change (e.g. Holbrook et al., 1997; Sagarin et al., 1999; Hiddink & Hofstede, 2008). Significant changes in aquatic communities have been strongly associated with global warming, suggesting that these ecosystems are extremely vulnerable to climate change (Richardson & Poloczanska, 2008). The effect of climate change on temperate inshore marine communities, specifically in rocky intertidal zones, has been demonstrated in a number of studies (e.g. Sagarin et al., 1999; Helmuth et al., 2006), with studies of the effects of climate on temperate fish communities in the North Atlantic (e.g. Perry et al., 2005; Hiddink & Hofstede, 2008) and eastern (Holbrook et al., 1997) and south-west Pacific (StuartSmith et al., 2009). The Antipodean region is recognized as a ‘hotspot’ for ocean warming (Ridgway, 2007). Since 1944, the East Australian Current (EAC) has extended poleward down the coast of Tasmania by approximately 350 km and the sea surface temperature has warmed at an average rate of 2.28°C per century (Ridgway, 2007; see also Fig. 1). Thus, biological responses to climate change in the region are expected to have already begun (Hobday et al., 2007; Ling et al., 2009). The relatively species rich, cool temperate coastal ichthyofauna of Tasmania is ideal for investigating temporal and spatial shifts in species composition in this hotspot. The region is wellseparated geographically from mainland Australia, but the respective faunas are loosely interconnected through the Bass Strait by a series of island groups that potentially form ‘stepping stones’ for the southward dispersal of adult fishes from northern bioregions. Although complex, the biogeography of southeastern Australia, which has been the subject of detailed investigation for the purpose of regional marine planning (IMCRA, 1996), is now reasonably well understood. The Tasmanian fish Figure 1 The average annual sea surface temperature anomaly from the long-term average calculated from the HadlSST dataset (monthly, 1 °C; Rayner et al., (2003); http://hadobs.metoffice.com/ hadisst/) for the area illustrated in the inset map [40–44° S, 147–151° E] for each year (dotted line) and for each decade (open bars) over the period 1880–2009. fauna has been described in a series of checklists and guides dating back to the late 1800s and early 1900s (e.g. Lord & Scott, 1924). In the ‘1980s’, these fishes were surveyed extensively and good intra-regional information was obtained on the distributions of most species (e.g. Last et al., 1983). However, since the mid-1990s many unusual records and sightings have been reported, including coastal species not previously reported from the region, poleward extensions of ‘1980s’ ranges, and increased local abundances in southern parts of Tasmania. Stuart-Smith et al. (2009) concluded that Tasmanian subtidal reef communities have remained stable over the past decade despite evidence of localized ocean warming (Ridgway, 2007). Nevertheless, they detected some species-level responses considered to be symptomatic of ocean warming, including southward range extensions of some fishes. They suggested that major changes in faunal structure probably occurred in the decade prior to commencement of their study; for example, forests of giant kelp (Macrocystis pyrifera) initially declined in the ‘1980s’ (Edyvane, 2003). Hence, by examining shifts over a longer time frame we should be able to gain better insights into the extent of change. Stuart-Smith et al. (2009) also observed that less abundant species often exhibited greater shifts than the dominant elements of the fauna, presenting challenges when monitoring climate impacts. Since 2006, when the senior author made an oral presentation describing range changes in south-eastern Australian fishes, patterns of distributional shift in the fauna have become widely accepted (e.g. Hobday et al., 2007) but have not been rigorously described. In addition, global warming may not be the only driver of change in the region – changes in the fauna may have occurred due to exploitation. Resolving these agents of change is important because not all distributional shifts are necessarily climate related. Recolonization may occur in response to changes in fishing pressure, allowing a return of fishes from populations in less heavily exploited regions. Attribution of change is important for improving coastal management strategies, as well as recording and predicting the impacts of climate change. The following hypotheses are evaluated using a combination of historical and present-day data sources: (1) the coastal ichthyofauna has experienced significant temporal losses of some elements since the ‘late 1800s’ evident from local extirpation or major reduction in population size and distribution of some species, and (2) the ichthyofauna has exhibited a marked change in composition since the ‘1980s’, with these differences represented by range extensions of warm-temperate provincial elements from the north. Herein, we define the coastal ichthyofauna as an assemblage of fishes (about 300 species) that have been recorded from the coastal zone of Tasmania. METHO DS Data sources The Tasmanian coastline is situated south of latitude 39°12′ S in the Australian Exclusive Economic Zone (EEZ) and includes the Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd 59 P. R. Last et al. Figure 2 The Maugean region of south-eastern Australia, including Tasmania. Arrows indicate the influence of adjacent bioregions, i.e. Flindersian (western warm temperate) and Peronian (eastern warm temperate). islands of the central (Kent and Hogan groups), eastern (Furneaux Group) and western (King Group) Bass Strait, and mainland Tasmania, including its adjacent islands (see Fig. 2). A temporal reconstruction of the coastal ichthyofauna was synthesized from a rich variety of sources because a complete time series of distribution and abundance data is lacking. Data were accessed from historical documents (published manuscripts, checklists and books), spearfishing competition results, field surveys, commercial fishing records, underwater observations, photographic records and other unpublished anecdotal information. Data sources varied in type, content, completeness and validity, but when combined, provided a robust overview of the composition and general distribution of species during each period. This information was summarized to produce distributional dossiers on candidate species for each of three periods: ‘late 1800s’ (1880–1925), ‘1980s’ (1970–85) and ‘present’ (1995–now) – a summary of these data is provided in Appendices S1–S3 in the Supporting Information and will be made available from the Tasmanian Coastal Climate Change Range Expansion Database and Mapping project (REDMAP) at http://www.redmap.org.au/. Common names of species referred to in this study follow the Australian Fish Names standard (Yearsley et al., 2006; http://www.seafood.net.au). Main datasets relevant to each period are discussed briefly below. ‘Late 1800s’ Coastal fish communities were not exploited by indigenous people (Luckman & Davies, 1978) and prior to the arrival of Europeans in the early 1800s were likely to be near pristine. By the mid 1800s, most distributional information on Tasmanian fishes had been obtained incidentally by naturalists. Soon after, fishing activities inshore increased dramatically and some populations soon displayed evidence of localized depletion (Johnston, 1883). Based on his own research and using an unpublished manuscript list (compiled by a local naturalist, M. 60 Allport), Johnston compiled the first annotated checklists of Tasmanian fishes. His work was thorough and comments on occurrence and commonness were provided for most of the 188 species known to exist in the region. This list was soon superseded by a revised version which included 214 species (Johnston, 1890). Johnston’s studies are particularly relevant to this investigation as data were obtained primarily from coastal assemblages, caught by beach seine, gillnet and hook and line, with some additional information on offshore species taken by pelagic fishing and bottom lining methods using hook, line and lure. In 1923, Lord (1923) produced a revised checklist, including 259 species, which was supplemented by additional species taken by exploratory trawl surveys of the region by the FRV Endeavour. Soon afterwards, he published the first guide to vertebrates of the region (Lord & Scott, 1924), which included notes on 262 fish species. These data have been summarized here based on a nomenclatural history and our knowledge of the contemporary fauna. ‘1980s’ The 1970s and first half of the 1980s were important periods for the exploration of marine biodiversity in this region with several surveys of inshore areas (e.g. Last, 1979; Edgar, 1984) and deeper parts of the continental shelf and slope (e.g. Last & Harris, 1981). Compositions of Tasmanian coastal fish assemblages and the distributions of their species were defined during the preparation of two regional guides (Edgar et al., 1982; Last et al., 1983). The most valuable supporting data for these publications came from field surveys, spearfishing competitions, fisheries statistics and underwater photographic records, the most important of which are documented below. 1. Field surveys. In 1982, Dr Barry Hutchins, an ichthyologist from the Western Australian Museum, completed an underwater survey of Tasmanian fishes as part of a broader investigation of the ichthyofauna of southern Australia. This 2-month Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd Long-term shifts in a temperate fish fauna survey was conducted in summer when seasonal vagrants are most abundant in the region. He used a combination of ichthyopoison samples and underwater observations and photographs to compile a list of about 140 species from 9 generalized sites located around the coastline of Tasmania. This survey led to the discovery of new cryptic species and provided important distributional information on the coastal ichthyofauna. Dr Hutchins had an exceptional knowledge of temperate Australian inshore fishes, so species missing from this survey are as important as those recorded, because their absence suggests that they are most likely either uncommon or absent on reefs in the region. Additional lists of species, based on underwater observations, were published by two of the authors (Last, 1979; Edgar, 1984), who also compiled additional distributional information on fishes in Tasmanian waters. 2. Spearfishing competitions. Underwater fishing is an efficient method of estimating the abundances of rare reef fishes (Lincoln Smith et al., 1989); hence, catches from competitions are a valuable but under-utilized historical data source. Catch data, collated from 12 competition sites held in northern, eastern and southern Tasmania in the 1970s, were pooled at each site to provide a total catch and to determine species composition for each site. Pooled data represented effort from 315 diver days (each about 4 h day-1) culminating in c. 1300 diver hours and the collection of 2502 specimens of 50 coastal species; this represents some 17% of the known Tasmanian coastal fish fauna. Numerous factors may have influenced the likelihood of capture for targeted species, including their presence at the site, diver experience, suitability of local habitat and weather conditions. While failure to capture a species at any site cannot be definitively interpreted as a non-occurrence, this sampling method (competition scoring) is based on capturing as many large species as possible, so moderately abundant and common fishes are typically thoroughly represented and a selection of rare species are usually also caught (Coll et al., 2004). 3. Underwater photographic records. The first photographic guide to coastal fishes of Tasmania and the Bass Strait (Edgar et al., 1982) was based on images taken by a local group of underwater photographers and scientists. Fourteen members of the Tasmanian Underwater Photographic Society dived throughout the region over a 2-year period to source images of as many species as possible; they captured images of 124 of the 290 coastal fishes then thought to occur in the region, as well as obtaining important information on their distributions and abundances. Effort data were not recorded but would have amounted to several hundred diver hours. Hence, species not photographed were considered to be cryptic, difficult to photograph or very rarely encountered during this period. 4. Complete regional guide. A guide to all 461 fishes then known to occur in Tasmanian waters was prepared soon after (Last et al., 1983). Much of the data were obtained through the sources described above, as well as government funded fishery surveys and personal records of commercial and recreational fishermen. Hence, notes on the local distributions and abundances of species, where specified, were used to characterize and summarize the fauna in the ‘1980s’. ‘Present’ Our ‘present’ knowledge of the coastal ichthyofauna is based on fishery catches (both commercial and recreational), diver observations and information provided by scientists, scuba divers and recreational and commercial fishers to REDMAP. Species distributions have been mapped in bioregionalization studies for regional marine planning of the Australian EEZ (IMCRA, 1996), and their biogeographic affinities have been determined from these datasets, which are held within the Codes for Australian Aquatic Biota (CAAB) database (http://www.cmar.csiro.au/ caab/). Broader-scale information on the distribution of warm temperate species was obtained from important regional guides (Hutchins & Swainston, 1986; Gomon et al., 2008). Newly recorded species and those with changes in the distributional profiles were identified; these included species with recently established breeding populations in Tasmanian waters, latitudinal range shifts and/or increases in abundance, or direct range expansions in south-east Tasmania where the former range was restricted or patchy. Eight classification categories (Table 1) were used to characterize these changes. Analysis Data sources, as listed above, were used to compile a list of Tasmanian fishes exhibiting temporal shifts in their distribution and/or abundance. Information was initially assembled for the entire fish fauna, with detailed data collation focused on the coastal assemblages which are best represented across the three time periods (i.e. ‘late 1800s’, ‘1980s’ and ‘present’). By combining available data we reconstructed change profiles for candidate species at each of these time intervals and assigned them to one or more of the eight main qualitative categories of distributional change as defined in Table 1. These categories consider the change status of species using the ‘1980s’ as a ‘control’ period (preceding recent observed changes in the ‘present’ fauna), based on whether species are new to the region, were once considered rare, have recovering populations or now have expanded local ranges and/or abundances (Categories 1, 3, 4, 6). A separate category was provided for species exhibiting distributional changes at the southern limit of the Tasmanian Province, the Bruny bioregion (Category 5). Other species, which were recorded from the ‘late 1800s’, disappeared from the fauna by the ‘1980s’ (Category 2) or are now threatened (Category 7); still others only occur in the region as extra-limital vagrants (Category 8). Species missing since the ‘late 1800s’ were further subdivided into those considered to be extinct locally, now confined to remnant populations, occurring periodically in the region, or doubtful records (based on erroneous data or misidentifications such as confusion with sibling species). Some species conform to more than a single category of change. For example, a species may have experienced a serious population decline since the ‘late 1800s’ to be considered as locally extinct by the ‘1980s’ (Category 2a), but is now recovering (Category 6) with significant changes in its regional abundance since the ‘1980s’ (Category 4). Evidence of change was inferred Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd 61 P. R. Last et al. Table 1 Classification of distributional change in the Tasmanian coastal ichthyofauna and numbers of families and species of fishes in each of these different categories based on the 37 families and 61 species with observed distributional and/or abundance changes. Category Definition 1. Previously rare or unlisted species Not listed or very rare in the ‘1980s’ but now resident or becoming established; primarily includes colonizers from biogeographic provinces to the north Recorded in the ‘late 1800s’ but very rare or absent from the fauna by the ‘1980s’: No longer occurs in the region Remains in the region but with an extremely contracted or remnant distribution Occurs periodically as mid-term residents (c. 2–10 years) Likely misidentification; probably confused with sibling species Resident exhibiting poleward range extension (usually southward) in part(s) of Tasmania since the ‘1980s’; extra-limital vagrants were excluded from this group Resident exhibiting an obvious abundance increase (usually southward) in part(s) of Tasmania since the ‘1980s’; where they were once not well represented or rare Rare or known from small populations in south-east Tasmania in the ‘1980s’ but now with much broader ranges; this scenario is usually accompanied by a general abundance increase Recorded from the region in the ‘late 1800s’, absent or at low abundance in the ‘1980s’, and now increasing; climate change may not be the sole attribution of change for these species No discernible change in distribution before the ‘1980s’ but now extremely restricted or declining in abundance and range Previously unlisted transient species from tropical Australian biogeographic provinces; probably migrated to Tasmania with the assistance of the East Australian Current (EAC) 2. Missing species a Local extinctions b Remnants c Periodical residents d Doubtful records 3. Expanded ranges 4. Abundance increases 5. Expanding in the south 6. Recovering species 7. Now threatened species 8. Extra-limital vagrants Families from a detectable decline or increase in either abundance, frequency of occurrence or geographic range. A spreadsheet providing supporting information and a dossier for each candidate species is provided in Appendices S1–S3. The main faunal lists for the ‘late 1800s’ (Johnston, 1883; Lord & Scott, 1924) and ‘1980s’ (Edgar et al., 1982; Last et al., 1983) were used to assess the local distributional status for each species during these time periods. Other historical data sources, discussed above, were used to iterate these assessments, and the statuses of species is summarized in Appendix S4, according to criteria outlined in Appendices S2 and S3. Secondly, distributional details were mapped for each species (Appendix S3) to eight Tasmanian bioregions (IMCRA, 1996) for the ‘1980s’ and ‘present’. Abbreviations for variables, bioregions, levels of change and the putative causes of change and their estimated confidence levels are provided in Appendix S1. Historical ranges of species in the ‘1980s’, based primarily on Hutchins & Swainston (1986), including specific distributional information largely from Tasmania (Last et al., 1983) and lists from the ‘late 1800s’, are summarized in Appendix S2. Present ranges, where they differ from the situation in the ‘1980s’, are compiled from the broad variety of sources specified above (Appendix S2). Other summary data compiled included primary habitat and indices of commonness, occurrence and breeding status (Appendix S3). Each species was also assigned to one of the following classes based on their biogeographic affinities in the Australian region (IMCRA, 1996): Bassian, primarily in the Bass Strait; Tasmanian, restricted cold temperate Australian species; 62 Species 8 12 3 2 1 9 15 3 3 1 9 23 21 30 14 16 3 3 1 2 3 4 Flindersian, western warm temperate species; Peronian, eastern warm temperate species; Southern Australia (S. Aust), widespread throughout temperate southern Australia; Tropical, mainly widespread off northern Australia; Widespread, ubiquitous in Australian seas. R ESULTS Some 37 families (over a third) and about 61 species (about a fifth) of the coastal ichthyofauna of Tasmania, which now consists of about 300 species, have, or appear to have, undergone important compositional shifts over the three periods considered (i.e. ‘late 1800s’, ‘1980s’ and ‘present’) leading to overall increased species richness and faunal complexity (Appendix S4). Changes were recorded in all eight of our classification categories (Table 1). These changes include the loss or drastic reduction in relative abundance of at least five large predatory fishes, and possibly another 14 unresolved or restricted species, treated in ‘late 1800s’ checklists (Johnston, 1883, 1890) (Table 2). More recently, there is evidence of present-day distributional shifts in 52 species (c. 17% of the coastal fish fauna), including the recent range extension of warm temperate species from the north that were either previously rare or unrecorded from the region (12 species), new extra-limital vagrants (4 species), those that now have expanded southern populations (23 species), those that have extended their ranges in southeastern Tasmania (16 species) and/or increased their abundances in Tasmania (30 species) (Table 1). Of these, 45 species, Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd Long-term shifts in a temperate fish fauna Table 2 Coastal species recorded by Lord & Scott (1924) exhibiting major changes in their occurrence status over the three temporal periods referred to in this study. Name (Lord & Scott, 1924) Current name (likely) Status late 1800s Status 1980s Present status Gyropleurodus galeatus Carcharias arenarius Orectolobus maculatus Pseudobatrachus dubius Histrio histrio Brachionichthys hirsutus Brachionichthys politus Hemirhamphus intermedius Trachichthys australis Centropogon australis Neosebastes panda Sillago maculata Trachurus novaezelandiae Sparus australis Sciaena antarctica Dactylopagrus morwong Latridopsis ciliaris Achoerodus gouldii Notolabrus celidotus Heterodontus galeatus Carcharias taurus (Orectolobus halei) Batrachomoeus dubius Histrio histrio Brachionichthys hirsutus Sympterichthys politus (Hyporhamphus melanochir) Trachichthys australis (Gymnapistes marmoratus) (Neosebastes scorpaenoides) (Sillago bassensis) (Trachurus declivis) (Acanthopagrus butcheri) Argyrosomus hololepidotus Nemadactylus valenciennesi Latridopsis ciliaris (Achoerodus viridis) (Notolabrus tetricus) Present Not uncommon Common Present Present Not uncommon Common and restricted Seasonal Probably common Infrequent Not common Doubtful Common Common Rare Not common Rare Common Present Locally extinct Locally extinct Extremely restricted Dubious record Dubious record Common and restricted Restricted Dubious record Absent Dubious record Dubious record Dubious record Dubious record Dubious record Locally extinct Possibly extinct Locally extinct Locally extinct Dubious record Locally extinct Locally extinct Extremely restricted Dubious record Dubious record Rare and restricted Extremely restricted Dubious record Recovering Dubious record Dubious record Dubious record Dubious record Dubious record Locally extinct Recovering Periodical resident Recovering Dubious record Names in brackets are likely valid names of misidentifications. representing 27 families (about 30% of the inshore fish families occurring in the region), exhibited major distributional shifts thought to be climate related. Changes in each of these categories are described further below. Previously rare or unlisted species Compositional knowledge of the Tasmanian fish fauna has expanded since the ‘1980s’ as additional species are discovered. Most recent additions to the checklist are fishes from the less comprehensively explored deep sea or the open ocean. Noncryptic, coastal species are less likely to escape detection, so in this region, which has been extensively surveyed, their recent, simultaneous appearances are likely to reflect ‘real’ change. Members of a group of 12 ‘previously rare or unlisted’ Tasmanian inshore fishes have expanded their distributions since the ‘1980s’ (Table 3). They include: three indigenous colonizing species from the north (previously unlisted); six species whose occurrence in the region in the ‘1980s’ was based on a few specimens (rare or extremely restricted); and three species that had become rare by the ‘1980s’ but are now recovering (see ‘Recovering species’ section below). There is no definitive evidence that any of these species have established self-sustaining populations, but as most are present as either adults or in sizeable aggregations it is likely that some are capable of breeding in the Tasmanian region. Most new regional records of these species come from the Furneaux Group and/or the eastern Tasmanian coast. A single soft-bottom species, the eastern shovelnose stingaree (Trygonoptera imitata) (Fig. 3a), which is abundant along the north- ern Bass Strait coast, has established populations in the Furneaux Group. This genus was not previously represented in Tasmanian waters. All other species are reef dwellers, over a third are wrasses (Labridae), and seven are Peronian species that are dominant members of a fish assemblage normally associated with barrens formed by the longspine sea urchin (Centrostephanus rodgersii). Missing species Distributional information from the ‘late 1800s’ (Johnston, 1883; Lord & Scott, 1924) varies in its detail, but at least 16 species ‘went missing’ from the Tasmanian fauna before the ‘1980s’ (Last et al., 1983), and another three recovering species suffered major declines in their ranges (Table 2). The group of ‘missing species’ includes three species that are now considered to be extinct locally, three with remnant distributions, a periodical resident and another nine species whose listings appear to be based on misidentifications and doubtfully occur in the region. Large predatory fishes, such as the greynurse shark (Carcharias taurus) (Fig. 3b), crested hornshark (Heterodontus galeatus) and mulloway (Argyrosomus hololepidotus), have not been observed in Tasmanian waters for nearly a century so we considered them to be extinct locally; whereas other large predators, the queen snapper (Nemadactylus valenciennesi) and eastern blue groper (Achoerodus viridis) (Fig. 3f), are now showing weak signs of recovery. These are all distinctive fishes, mostly well regarded as recreational or commercial species, and are unlikely to have been overlooked if present. Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd 63 P. R. Last et al. Table 3 Coastal species previously unlisted (U), rare (R) or extremely restricted (R&R) in Tasmanian seas during the ‘1980s’ that are now more widespread or recovering (RE); includes their biogeographic affinity, location observed, occurrence, primary habitat type, association with longspine sea urchin barrens and local breeding status. Scientific name Status Biogeographic affinity Location Occurrence Habitat Trygonoptera imitata Aplodactylus lophodon Notolabrus gymnogenis Achoerodus viridis Trachichthys australis Nemadactylus valenciennesi Gymnothorax prasinus Latropiscus purpurissatus Nemadactylus douglasii Chromis hypsilepis Ophthalmolepis lineolatus Eupetrichthys angustipes U U U RE RE RE R R R R&R R&R R&R Bassian Peronian Peronian Peronian S. Aust Flindersian S. Aust S. Aust Peronian Peronian Peronian Peronian Flinders C Bass S Bass S Bass/NE Flinders W NE S Bass NE E E/SE NE/SE Localized Patchy Patchy Patchy Common Patchy Patchy Patchy Common Patchy Patchy Patchy Soft bottom Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Urchin barrens Yes Yes Yes Yes Yes Yes Yes Breeding Yes? No No No Yes? Yes? Yes? Yes? Yes? Yes? Yes? Yes? ? = unconfirmed. Location: C Bass, central Bass Strait islands; E, east; Flinders, Flinders Island; NE, north-east; S Bass, southern Bass Strait; SE, south-east; W, west. The blue moki (Latridopsis ciliaris) is primarily a New Zealand species that appears to recruit periodically across the Tasman Sea into southern Australian waters (Yearsley et al., 1999). It was recorded from Tasmanian waters in the late 1880s (Johnston, 1890) but its occurrence locally was questioned by Lord & Scott (1924). The species was omitted from Last et al. (1983) because there had been no confirmed records from the 20th century despite a comprehensive search for information or specimens. However, soon after (c. 1985), juveniles were presented to the senior author from eastern Tasmania, presumably following a large spawning event in the Tasman Sea. Sightings of juveniles were frequent in the late 1980s but this cohort disappeared shortly after an adult fish was captured in southern Tasmania in the early 1990s. This species has not been recorded from the region since, suggesting that its occurrence in the region is periodical. Three species occur in remnant populations that have not recovered in recent times. A wobbegong (assumed to be the gulf wobbegong, Orectolobus halei) was considered common by Johnston (1883), but by the ‘1980s’ was confined to a handful of resident adults, observed regularly at a very small, isolated reef off Flinders Island (Furneaux Group). According to local divers this population still exists (c. 2009) but its range has barely expanded beyond this patch. Similarly, two handfishes have suffered serious range reductions and are now threatened (see ‘Now threatened species’ section below). The ‘late 1800s’ lists contain records (nine taxa) that are doubtful and probably resulted from the erroneous application of names to well-known Tasmanian species; most of these are names of close relatives or sister species. However, three distinctive fishes, the eastern frogfish (Batrachomoeus dubius), the sargassum fish (Histrio histrio) and the eastern fortescue (Centropogon australis), are not easily confused with other local species and may have once existed in the region; three of these genera are not otherwise recorded locally. 64 Species with an expanded range Twenty-three species display recent southward shifts in their range limits, and about half of these (12 species) also show subtle increases in their abundances within their extended ranges (Table 4). Almost all of these fishes are reef dwellers (91%) and about half are dominant coastal elements of the Peronian Province (11 species); other biogeographic groups include widespread southern Australian (seven species), Flindersian (four species) and Bassian (single species) fishes. This pattern exists in 14 families with labrids (four species) and kyphosids (three species) being the most important groups. Warm temperate surf-zone fishes, the silver drummer (Kyphosus sydneyanus) (Fig. 3c) and rock blackfish (Girella elevata), which once had very restricted distributions in the region (Last et al., 1983), are now more abundant in the north and east, particularly in the Furneaux Group where schools of G. elevata sometimes include gravid individuals. Girella elevata is one of the five most commonly speared fishes in competitions off Sydney (Lincoln Smith et al., 1989). Other reef species, such as the onespot puller (Chromis hypsilepis), the snakeskin wrasse (Eupetrichthys angustipes) and the southern Maori wrasse (Ophthalmolepis lineolatus), which were restricted locally to the Kent Group (central Bass Strait), have now been recorded from several localities to the south. While seven species have broadened their ranges in Bass Strait (four in the southern Bass Strait, two off Flinders Island and one off the central Bass Strait islands), the most striking expansions occur along the southeast (12 species) and/or east (five species) coasts. A large cheilodactylid, the blue morwong (Nemadactylus valenciennesi), is now caught infrequently off the northern west coast and remains the only species known to display a poleward shift off the west coast. Weaker trends in this largely remote region probably reflect poorer sampling effort rather than stability in community structure. Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd Long-term shifts in a temperate fish fauna Figure 3 Underwater photographs representing species from each of the eight change categories: (a) eastern shovelnose stingaree (Trygonoptera imitata), a previously unlisted species; (b) greynurse shark (Carcharias taurus), a missing species; (c) silver drummer (Kyphosus sydneyanus), an expanded range species; (d) Castelnau’s wrasse (Dotalabrus aurantiacus), a species with an increased abundance; (e) snapper (Pagrus auratus), a species with expanded range in south-eastern Tasmania; (f) eastern blue groper (Achoerodus viridis), a recovering species; (g) spotted handfish (Brachionichthys hirsutus), a now threatened species; (h) Queensland groper (Epinephelus lanceolatus), an extra-limital vagrant. Photographs (b), (e), (f) and (h) were taken outside Tasmanian seas. More abundant species Thirty species exhibit an increase in abundance in some part of their Tasmanian range (Table 4). This group comprises families, with more than half being perch-like fishes (c. 63%) and a sixth elasmobranchs (c. 17%). Generalized increases were observed across the region: Tasmania-wide (four species), southern Bass Strait and north-east (12 species), east (nine species), south-east (13 species) and west (one species). Twice as many species appear to have undergone abundance increases along the eastern coast (23 species) as along the northern coast (12 species). These species occur in a mixture of habitats but twothirds are reef fishes (20 species) with a smaller mix of soft bottom (four species), seagrass (three species), pelagic (two species) and inshore demersal fishes (one species). Half of the fishes in this category are warm temperate Australian endemics and half of them are widespread in southern Australia (15 species). The warm temperate Peronian (eight species) and Flindersian (seven species) provinces are about evenly represented. At least 14 species (e.g. Atypichthys strigatus, Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd 65 P. R. Last et al. Table 4 Coastal species that have undergone recent poleward shifts and/or increases in abundance in Tasmanian waters, including the location observed, biogeographic affinity, primary habitat type and local breeding status. Scientific name Heterodontus portusjacksoni Trygonorrhina dumerilii Dasyatis brevicaudata Trygonoptera imitata Urolophus paucimaculatus Myliobatis australis Gymnothorax prasinus Latropiscis purpurissatus Trachichthys australis Platycephalus laevigatus Hypoplectrodes maccullochi Hypoplectrodes nigroruber Pomatomus saltatrix Seriola lalandi Pagrus auratus Girella elevata Girella tricuspidata Girella zebra Kyphosus sydneyanus Atypichthys strigatus Scorpis aequipinnis Scorpis lineolata Enoplosus armatus Chromis hypsilepis Parma microlepis Chironemus marmoratus Aplodactylus lophodon Cheilodactylus nigripes Dactylophora nigricans Nemadactylus douglasii Nemadactylus valenciennesi Achoerodus viridis Dotalabrus aurantiacus Eupetrichthys angustipes Notolabrus gymnogenis Ophthalmolepis lineolatus Haletta semifasciata Heteroscarus acroptilus Odax cyanomelas Eubalichthys mosaicus Omegophora armilla Shift Abundance increase Biogeographic affinity Habitat Breeding S Bass SE S Bass SE S. Aust Flindersian S. Aust Bassian S. Aust S. Aust S. Aust S. Aust S. Aust Flindersian Peronian S. Aust S. Aust S. Aust S. Aust Peronian Peronian Flindersian S. Aust Peronian Flindersian Peronian S. Aust Peronian Peronian Peronian Peronian Flindersian Flindersian Peronian Flindersian Peronian Flindersian S. Aust Peronian Peronian S. Aust S. Aust S. Aust S. Aust Peronian Reef Soft bottom Soft bottom Soft bottom Soft bottom Soft bottom Reef Reef Reef Seagrass Reef Reef Pelagic Pelagic Inshore Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Reef Seagrass Reef Reef Reef Seagrass Reef Reef Reef Reef No No No? Yes? Yes No? Yes? Yes? Yes? Yes Yes? Yes? No No No Yes Yes Yes No? Yes Yes Yes Yes Yes? No Yes No Yes Yes Yes? Yes? No Yes Yes? No Yes? Yes Yes Yes No Yes Flinders S Bass Flinders SE SE SE SE SE SE E E SE SE SE NE S Bass Flinders SE S Bass S Bass Tas Tas Tas N/E SE E/SE NE N/E E/SE N/E Tas C Bass E/SE E/SE W NE NE W E/SE NE/SE S Bass E/SE E/SE SE S Bass E/SE E/SE S Bass SE ? = unconfirmed. Location: C Bass, central Bass Strait islands; E, east; Flinders, Flinders Island; N, north; NE, north-east; S Bass, southern Bass Strait; SE, south-east; Tas, Tasmania; W, west. Scorpis lineolata, Dotalabrus aurantiacus (Fig. 3d) and Haletta semifasciata) now occur as both adults and juveniles where their abundances have recently increased, and are likely to be breeding at these locations (Table 4). However, another six species (i.e. Pagrus auratus (Fig. 3e), Pomatomus saltatrix, Seriola lalandi, Eubalichthys mosaicus, Heterodontus portusjacksoni and Trygonorrhina dumerilii), are either known to breed elsewhere or are unlikely to breed in Tasmanian waters. 66 Species with expanded populations in the south-east Sixteen species appear to have expanded their ranges in southeast Tasmania by exhibiting either a broader distribution or general increase in abundance in the Bruny bioregion (Table 5). These fishes are generally large to medium-sized, with elasmobranchs well represented (four species). Most were known from the bioregion in the ‘late 1800s’ and ‘1980s’, but were typically Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd Long-term shifts in a temperate fish fauna Table 5 Coastal species previously known from south-east Tasmania that have recently expanded their range and/or abundance in this region, classified by biogeographic affinity, primary habitat type and local breeding status. Scientific name Biogeographic affinity Habitat Breeding Heterodontus portusjacksoni Dasyatis brevicaudata Urolophus paucimaculatus Myliobatis australis Pomatomus saltatrix Seriola lalandi Pagrus auratus Haletta semifasciata Odax cyanomelas Platycephalus laevigatus Girella zebra Scorpis aequipinnis Cheilodactylus nigripes Dotalabrus aurantiacus Girella tricuspidata Omegophora armilla S. Aust S. Aust S. Aust S. Aust S. Aust S. Aust S. Aust S. Aust S. Aust Flindersian Flindersian Flindersian Flindersian Flindersian Peronian Peronian Reef Soft bottom Soft bottom Soft bottom Pelagic Pelagic Inshore Seagrass Reef Seagrass Reef Reef Reef Seagrass Reef Reef No No Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes more widespread and abundant in the Bass Strait than in areas to the south. The level of range expansion in this bioregion varies between species. For example, the smooth stingray (Dasyatis brevicaudata) has gone from being an occasionally occurring, seasonal transient to a more widely distributed species that is abundant and possibly resident at some locations. The rock flathead (Platycephalus laevigatus), abundant in parts of the Bass Strait but missing from the west and east, was represented in the south-east in the ‘1980s’ by a small extra-limital population in one small embayment; it has now expanded its range to become widespread throughout large sheltered bays of the south-east. Reef species, such as the sea sweep (Scorpis aequipinnis) and herring cale (Odax cyanomelas), which were typically abundant only in the Bass Strait, are now widespread on reefs along the eastern and south-eastern coastlines. The snapper (Pagrus auratus) was thought to be confined to the north and east coasts in the ‘late 1800s’ (Lord & Scott, 1924). However, while they have been caught infrequently by local fishermen in the south in recent decades, their abundance appears to have increased widely across their entire range and they are now targeted by fishers in parts of southern Bass Strait and the Furneaux Group. Abundances appear to have increased for all 16 species near the southern limits of their ranges. This assemblage consists of nine widespread southern Australian, five Flindersian and two Peronian species. These fishes occupy a variety of niches exhibiting preferences for either soft bottoms, seagrasses, reefs or inshore demersal habitats. Coexisting adults and juveniles indicate that at least 10 of these species are now likely to breed in the bioregion. Recovering species A small group of species, which were once well represented in the region based on early historical information but were missing or represented by remnant populations during the ‘1980s’, are now showing signs or recovery or have re-recruited to the region. These species include: Trachichthys australis, Nemadactylus valenciennesi and the eastern blue groper, Achoerodus viridis (Fig. 3f). The recent rediscovery of juveniles of A. viridis, a major predator of urchins, in the north and north-east, may have important ecological implications in the future. This large wrasse was once considered to be a ‘common species around the rocky section of the coast’ (Lord & Scott, 1924), but was later excluded from the Tasmanian fish fauna (Last et al., 1983) as it had not been seen for more than 50 years and was considered to be extinct locally. The long-term survival of N. valenciennesi and A. viridis in the region is likely to be dependant on the implementation of prudent management plans associated with fishing. Similarly, the unmistakable cave-dwelling southern roughy (Trachichthys australis), which was said to ‘inhabit rocky reefs’ (Lord & Scott, 1924) but was not observed during extensive underwater surveys around Tasmania in the ‘1980s’, is now common off Flinders Island (P. Nichols, personal communication). Now threatened species Handfishes (family Brachionichthyidae), which are endemic to Australia, are represented by at least 14 small species, and all but three of these occur in Tasmanian seas (Last & Gledhill, 2009). Two species, Brachionichthys hirsutus (Fig. 3g) and Sympterichthys politus, both occurred in healthy populations in the ‘1980s’, primarily in the south-east, but have now undergone serious population declines and are now listed as threatened (e.g. Last et al., 2007). Data are insufficient to ascertain the cause(s) of these declines, but appear, at least in some instances, to be related to critical habitat loss or damage. Extra-limital vagrants Four widely distributed transient species represent new records for the Tasmanian region. All of these fishes occur in tropical seas, and while two of them are typically pelagic, all occur in coastal habitats elsewhere in Australia, e.g. the Queensland groper (Epinephelus lanceolatus) (Fig. 3h). There are few historical records of the tiger shark (Galeocerdo cuvier) from south of Sydney but there have been several captures in the last decade off north-east Tasmania. Tropical vagrants are rare in the listed fauna (11%), so the recent arrival of these species is not inconsistent with a southward distributional shift in composition. While all of these species were of reproductive size, they are unlikely to breed in southern seas. Another tropical offshore demersal species, the thorny tinselfish (Grammicolepis brachiusculus), was also captured from the region in 2003. Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd 67 P. R. Last et al. D I SC U SSI O N The effects of climate change on marine communities can be manifested as shifts in the latitudinal distributions of species. However, not all latitudinal boundaries are set by climate, and localized hydrographic features need to be considered (Helmuth et al., 2006). Oceanographic models have demonstrated that climate change is highly likely to cause the EAC flow to strengthen and extend southward, in turn resulting in further warming of the Tasman Sea. Increasing sea surface temperatures over the last 60 years off eastern Tasmania are primarily the result of changes in the EAC rather than global surface fluxes (Ridgway, 2007). The surface temperatures in the time-scale examined by Ridgway (2007) equate to an increase of about 2.3°C/100 years and a corresponding poleward advance by the EAC of about 350 km. Over the time-scale of this investigation (‘late 1800s’ to ‘present’) there have been strong increases in water temperature, above the long-term average for the region, in each decade since 1970 (Fig. 1). Increased water temperatures in the Tasman Sea are likely to have a cascading effect through local marine ecosystems, probably most evident in, but not exclusive to, inshore marine ecosystems. For example, biological responses to these changes have been recorded off the east coast of Tasmania for sea urchins (Ling et al., 2009) and shore crabs (Thresher et al., 2003). Long-term empirical data on the distributions of marine biota collected using comparative methods are rarely available. In their absence, we are forced to make best use of often disparate and largely non-quantitative data sets – in our case mixtures of literature, field, photographic and other observational records, which together provide a useful basis for comparing distributional patterns. The strength of our argument in identifying change rests on the quality and reliability of accumulated information for each of the three periods, particularly the ‘1980s’, which we consider to be a tipping point for potential changes. These data were compiled from a period of high scientific activity where consistent absences of non-cryptic species across the region are reliable indicators of extreme rarity or non-occurrence. As discussed above, the argument for ‘real’ change is based on the regularity of this pattern, shared across supraspecific taxa. Our synthesized data strongly support changes in ichthyofaunal distribution over the span of three decades (‘1980s’ to ‘present’). Multiple cases of latitudinal shifts in geographic range, and corresponding increases in abundances of 52 Tasmanian coastal fish species, provide strong inferential evidence of a changing environment (Root et al., 2003). Stuart-Smith et al. (2009) concluded that there has been no major change in the structure of Tasmanian reef communities in the last decade, but did note that some species changed in abundance; one of these, Scorpis lineolatus, exhibited a five-fold increase in abundance. We report changes over longer time-scales than those of StuartSmith et al. (2009), including species now present that were once considered rare or unrecorded from the region, others primarily confined to Bass Strait that have become resident or occur frequently further south, as well as those that now have expanded 68 populations and ranges in the south-east. Also, a small suite of previously unrecorded vagrants from tropical habitats has been recorded, providing further evidence of climate-induced change. A large proportion of the species (c. 40%) showing distributional and/or abundance changes in Tasmanian waters have widespread distributions encompassing all of the southern Australian biogeographical provinces (see IMCRA, 1996). These species are successful inhabitants of warm temperate Australian seas and are likely to become better represented off Tasmania as sea temperatures increase. Eight species (17%) exhibiting distributional and/or abundance changes in Tasmanian waters are of a Flindersian (western warm temperate) origin. All of these species displayed either abundance increases or a southward range expansion, but only one had been recorded previously as rare in Tasmanian waters (Tables 3 & 4). Twelve species with Peronian (eastern warm temperate) affinities appear to have shifted their ranges in association with the recent southward extension of the longspine sea urchin (Centrostephanus rodgersii). However, an additional five species with Peronian distributions, but not associated with barrens created by these urchins, have recently expanded their ranges in Tasmanian waters. Interestingly, only two of the species with expanded ranges and/or abundances in south-eastern Tasmania (the Bruny Bioregion) are Peronian species. Only one Bassian (Bass Strait) species, Trygonoptera imitata, has extended its range southward into Tasmanian waters. Colonizing species might be expected to first appear closest to the source of recruitment from adjacent regions. Hence, the Bass Strait Islands act as ‘stepping stones’ or distributional pathways south. In the ‘1980s’, three typical Peronian species (Chromis hypsilepis, Ophthalmolepis lineolatus and Eupetrichthys angustipes) were confined to the Kent Group (central Bass Strait), but all of these now have expanded ranges east and south. Other southern Bass Strait species have extended their ranges southward along the east coast, and often into bays of the south-east. Breeding range data, definitive evidence that species are established or resident in a region rather than extra-limital or transient, is not widely available for Australian fishes. However, populations of some species (e.g. Girella elevata), until only recently considered to be rare in the region, have been observed with gravid individuals (P. Last, unpublished data). Other nonmigratory species (e.g. Urolophus paucimaculatus, Haletta semifasciata) presumably breed within their new extended ranges as they now occur there as both adults and juveniles. These species are not known to undertake long migrations so their adult populations, which are often widely separated, are unlikely to be connected reproductively; this is particularly evident for Bass Strait fishes that have disjunct populations in the south-east. Not all the changes observed can be attributed to climate change. Most changes in faunal structure before the ‘1980s’ are likely to be due to anthropogenic rather than environmental factors. Some apical predators, including sharks (e.g. Carcharias taurus, Orectolobus halei) and large teleosts (e.g. Argyrosomus hololepidotus, Nemadactylus valenciennesi, Achoerodus viridis), Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd Long-term shifts in a temperate fish fauna appear to have experienced serious range reductions or regional extirpation since the 1880s. Johnston (1883) observed that estuaries of the south-east once contained an abundance of commercial fishes and juveniles of other species. However, unprotected areas near population centres were soon ‘rendered almost barren’ by intensive beach seining. At the same time, the graball (a type of gillnet), was used to catch reef fishes in nearby bays and over shallow reefs, and this method is still used by both commercial and recreational fishers in Tasmania (Metcalf et al., 2008). Edgar & Barrett (1999) have shown that large fishes are particularly vulnerable to gillnetting practices; hence, this method is likely to be destructive to fish communities over long time intervals. While inconclusive, it is likely that apparent periodic or regional extinctions of large sharks and teleosts during the 1900s were due primarily to the effects of fishing. Some of the species putatively impacted are particularly vulnerable to certain fishing practices (Pogonoski et al., 2002). By 1969, populations of eastern blue groper (Achoerodus viridis) had been seriously reduced off New South Wales and a total ban on their capture was implemented in 1980 because large catches were being taken by commercial gillnets (Pogonoski et al., 2002). This species, which was marketed in Tasmania in the 1800s (as adults exceeding 1 m) and described as common in the 1920s, subsequently went missing until a few juveniles were discovered off the northern coast in 2004. However, the likelihood of A. viridis re-establishing breeding populations in Tasmania is low; males take about 10 years to mature (Gillanders, 1995) and are unlikely to reach this stage due to fishing pressure unless protective measures are implemented. Elasmobranch fishes are particularly vulnerable to some fishing methods, particularly gillnetting (Walker et al., 2005). Of the 10 species exhibiting some form of change in Tasmanian waters, one is a new record, one is a seasonal vagrant, five have expanded their ranges or increased their abundance and three appear to have suffered significant population declines. Elasmobranchs have K-selected life-history strategies (i.e. they have low productivity, low fecundity, mature at a late age and are slow growing), making them especially vulnerable to threatening processes such as intense fishing pressure (Stevens et al., 2000). The IUCN Species Survival Commission recognized this issue and established the Shark Specialist Group (SSG) to provide assessments for all sharks and rays as part of their Red List of Threatened Species® program (IUCN, 2008). Two sharks appear to have undergone significant population declines in Tasmanian waters. Carcharias taurus is listed as vulnerable by the IUCN Red List due to its extremely low reproductive rates and population declines recorded off eastern Australia and South Africa (Pollard & Smith, 2000). Catches of wobbegong sharks (including Orectolobus halei) off south-eastern Australia, particularly New South Wales, have declined markedly in recent decades (Huveneers et al., 2007). These declines resulted in populations of two wobbegong species in New South Wales initially being listed as Vulnerable by the IUCN Red List (Cavanagh et al., 2003). Thus, it is likely that threatening processes acting on these species have significantly reduced, or possibly eliminated, the populations of these sharks in Tasmanian waters. Fishery impacts are also evident in offshore assemblages. Commercial fishes, the gemfish (Rexea solandri) and blue-eye trevalla (Hyperoglyphe antarctica), which typically occur in deep water along the continental slope, were once caught trolling at the surface off south-east Tasmania (Lord & Scott, 1924). In the case of gemfish, populations have been subjected to overfishing off south-eastern Australia (Punt & Smith, 1999) and this species is no longer abundant, even in its primary habitat. Thus, a number of the changes to components of the fauna of this region are best attributed to non-climate stressors. We have highlighted examples of both non-climate and climate-related impacts on a wide diversity of fishes in this study, with 27 families (including six elasmobranch families) displaying recently altered distributions off Tasmania. The majority of species showing distributional and/or abundance changes in Tasmanian waters are reef-dwellers (66%). Most of these families are represented by a single species, but there are multiple species from the families Cheilodactylidae, Kyphosidae, Labridae and Serranidae, of which all but one are reef dwellers. Previous studies have shown that reef fishes are useful indicators of environmental change (e.g. Holbrook et al., 1997); however, changes are also evident within the pelagic fauna. The frigate mackerel (Auxis thazard) was recorded in the 1800s but has been rarely seen in Tasmanian waters, until schools were observed recently off north-eastern Tasmania. Anecdotal information provided by recreational fishers indicates that abundances of other warm water tunas and billfishes have increased in recent years. While there have been major range shifts in some dominant coastal fishes, particularly those that occur primarily in the Bass Strait, many other species have not undergone any obvious distributional shift. For example, no distributional changes have been observed for the common Bass Strait reef species, the horseshoe leatherjacket (Meuschenia hippocrepis), the yellowstriped leatherjacket (Meuschenia flavolineata), the pencil weed whiting (Siphonognathus beddomei) and the scalyfin (Parma victoriae), and a soft-bottom species, the southern bluespotted flathead (Platycephalus speculator). The absence of poleward movement in these taxa, despite obvious shifts in other co-occurring species, suggests that it is difficult to predict which species will exhibit induced range shifts. In situ changes in abundance, physiology or phenology (Hobday et al., 2007) of these species may still mean that climate change is having an impact, but without more detailed study impacts remain unknown. The distributions of these important, non-cryptic species need to be monitored in the coming years to assess their future responses to environmental change. While we have focused on changes in fish distributions, habitat shifts in response to environmental change can also have a considerable cascading effect in a biological community; an example of this off the Tasmanian coastline is the longspine sea urchin. This shallow-water urchin, which is found also off northern New Zealand and the Kermadec Islands (Andrew & Byrne, 2007), has a primarily Peronian-derived distribution in Australia. Before 1978, it was only known in Tasmanian waters from the central northern Bass Strait but is now established Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd 69 P. R. Last et al. along most of the east coast of Tasmania, a change attributed to a strengthening of the EAC and associated ocean warming (Ling et al., 2009). Newly formed urchin barrens are likely to result from both climate change and reduced predation pressure associated with commercial harvesting of the urchin’s key predator, the southern rock lobster (Jasus edwardsii). Our study indicated that 7 of the 12 species that were rare, previously unlisted or recovering in Tasmanian waters are strongly associated with Centrostephanus rodgersii barrens (Table 3). Of these seven species, six have a Peronian origin, providing strong circumstantial evidence that these species have shifted their distributions southward in relation to latitudinal shifts in the distribution of C. rodgersii or its associated barrens. Latitudinal shifts in the distribution of biological facies and their associated biota have not been well researched, but some coralline algal communities also appear to have expanded their ranges southward in recent years (P. Last, unpublished data). Other non-climate-related change within the fauna is exemplified by a small group of introduced species. Two New Zealand coastal reef fishes, the triplefins Forsterygion gymnota and Forsterygion varium, were introduced into the Derwent Estuary and D’Entrecasteaux Channel, south-eastern Tasmania (Clements et al., 2000). These species were initially thought to be Tasmanian endemics (Last et al., 1983). At least four New Zealand marine invertebrate species have been introduced into Tasmanian waters, probably with shipments of live oysters around the 1920s (Edgar, 1997), and the triplefins may have been transported in the same way. The importance of habitat availability should not be underestimated when attempting to predict the responses of species to environmental change. The flathead Platycephalus laevigatus, a Flindersian species, has expanded its range in the bays of southeast Tasmania and is now more widespread and abundant in seagrass habitats of this region. However, despite these changes, it has never been recorded off the central east coast, possibly as a consequence of the unavailability of appropriate habitat. Thus, future changes in faunal distribution may occur, not only in response to direct changes in the physical environment (water temperature) but to indirect changes in preferred habitat (Hobday et al., 2007). C O N C L U SI O N S This paper set out to investigate two hypothetical changes in the ichthyofauna off Tasmania in the south-eastern Australia climate change hotspot. We hypothesized that the coastal fish assemblages have exhibited a marked change in composition since the ‘1980s’. The results of this study showed that about a fifth (61 species) of the Tasmanian coastal fish fauna have, or appear to have, undergone important compositional shifts since the 1800s. Examination of longer-term fish composition data revealed substantial changes to the coastal ichthyofauna of Tasmania, strongly supporting the first hypothesis. In addition, to illustrate that not all change might be climate-related, we hypothesized that certain elements of the Tasmanian ichthyofauna have been lost or severely depleted since the ‘late 1800s’. At 70 least five, possibly up to 19, species have undergone serious declines and are possibly extinct locally. Localized extinctions, particularly of apical predators such as the greynurse shark and mulloway, are likely to be attributed to fishing pressure. Other species, such as the gulf wobbegong, now have extremely restricted distributions and are likely to face a similar fate without intervention. Thus, the fauna of this region was not ‘pristine’ before this new invasion associated with warmer temperatures began. This paper highlights, however, that many warm temperate species have colonized the cool temperate Tasmanian region or substantially expanded their ranges, consistent with a strengthening of the EAC and associated rises in sea temperature. Although climate change is considered beneficial to a number of species, it will also be detrimental to others (Poloczanska et al., 2008). The effect of environmental change on species endemic to cool temperate Australia has not been fully investigated, but the lack of refugia south of Tasmania (i.e. the southernmost limits of the Australian continental shelf), especially for coastal species with population centres in southern Tasmania, is of concern and should be a focal point of future research. Reliable baselines are needed to evaluate further change, and to that end, recent bioregionalization studies using national fish datasets (e.g. IMCRA, 1996) can be used for this purpose. Similarly, long-term scientific and community-based monitoring will be important in documenting changes in the composition of marine ecosystems. The paucity of documented impacts of climate change in the marine realm of the Southern Hemisphere is due to the resource-intensive and expensive nature of marine monitoring (Richardson & Poloczanska, 2008). Volunteer recording schemes, or ‘citizen science’ projects such as REDMAP, allow for detailed monitoring to continue and expand with comparatively little financial investment, but offer scope for the generation of much-needed baseline data to enhance monitoring efforts of science organizations. AC K NO WL EDGEMENTS Numerous colleagues, divers, fishers and the general public have provided unpublished data and anecdotal records over a number of decades. We acknowledge the wealth of information that has been forwarded so enthusiastically from such sources. In particular, we acknowledge assistance from professional fisherman Bill Smedley, and divers, including: Karen GowlettHolmes, Mike Nichols, Andrew Pender, Mike Sugden, Malcolm Wells and numerous divers from the Australian Underwater Federation. Neville Barrett (Tasmanian Aquaculture and Fisheries Institute, TAFI), Barry Hutchins (formerly of the Western Australian Museum) and Rick Stuart-Smith (TAFI) have kindly provided unpublished data and advice. John Pogonoski (CMAR) assisted with editing of the manuscript. Alastair Graham and Louise Conboy (CMAR) have provided assistance in the collation of data and collection support. Thanks also to Nick Mooney and Ian Banks for use of underwater photographs. 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Appendix S3 Summary of historical records and biogeographic affinities of candidate species. Appendix S4 Coastal species exhibiting distributional change in Tasmanian waters since the ‘late 1800s’ and their current occurrence status and change category. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer-reviewed and may be reorganized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. B IO SK ETC H Peter Last is leader of the Biogeography and Taxonomy team of CSIRO Marine and Atmospheric Research in Hobart, Australia and is curator of the Australian National Fish Collection (ANFC), with interests in biogeography, systematics and phylogeny of Indo-West Pacific marine fishes as well as bioregional marine planning for the Australian region. Editor: Julian Olden Global Ecology and Biogeography, 20, 58–72, © 2010 Blackwell Publishing Ltd