Identifying hotspots for biodiversity management using rank abundance distributions

Aim Identification of biodiversity hotspots has typically relied on species richness. We extend this approach to include prediction to regional scales of other attributes of biodiversity based on the prediction of Rank Abundance Distributions (RADs). This allows us to identify areas that have high numbers of rare species and areas that have a rare assemblage structure. Location Continental slope and shelf of south‐western Australia, between 20.5 and 30° S and depths of 100–1500 m. Methods We use a recently developed method to analyse RADs from biological surveys and predict attributes of RADs to regional scales from spatially abundant physical data for demersal fish and invertebrates. Predictions were made for total abundance (N), species richness (S) and relative evenness at 147,996 unsampled locations using data from two spatially limited surveys. The predictions for S and relative evenness were then independently split into categories, creating a bivariate distribution. The RAD categories are mapped spatially between 20.5 and 30° S to depths of 1500 m to allow identification of areas with rare species and assemblage structure across this region. Results Rank abundance distributions for demersal fish vary with large scale oceanographic patterns. Peaks in abundance and unevenness are found on the shelf break. The bivariate distributions for richness and evenness for both fish and invertebrates show that all assemblage structures are not equally likely. The RAD categories identify regions that have high numbers of rare species and areas with unique assemblage structure. Main conclusions Predicted RADs over large regions can be used to identify biodiversity hotspots in more detail than richness alone. Areas of rare species and rare assemblage structure identified from fish and invertebrates largely overlap, despite the underlying data coming from two different data sets with two different collection methods. This approach allows us to target conservation management at species that would otherwise be missed.     

Seascape structure and complexity influence temperate seagrass fish assemblage composition

Understanding how spatial patterning relates to ecological processes is fundamental to define important species–environment associations at broader scales. Analyses targeting habitat structure (i.e. composition and configuration) in terrestrial landscapes are increasing, but similar studies in marine landscapes are still relatively uncommon. In this study, we explored how seascape structure and complexity (determined from significant spatial pattern metrics) influenced summer and autumn fish assemblage composition in 30 seagrass (Zostera marina) meadows along the west coast of Sweden. Species density was not influenced by seascape structure in any season. In contrast, the majority of significant fish assemblage variables were influenced by seascape structure during the summer (i.e. abundance and proportion of juveniles, abundance of Labridae and abundance of occasional shallow‐water visitors) whilst fewer in the autumn (i.e. abundance of occasional shallow‐water visitors and Synganthidae). For instance, less complex seascapes were more suitable for juvenile assemblages in summer, as these seascapes exhibit larger patch sizes of appropriate habitat (e.g. Z. marina) and less edge boundaries providing refuges from predators and food resources. Abundances of migrating fish, such as the sea trout Salmo trutta, also responded positively to a less complex seascape in the summer though perhaps ecological processes, such as prey availability, were additional contributing factors driving this relationship. High complexity seascapes only had a positive influence on the abundance of taxa using multiple habitats (Labridae during the summer). Our study shows that fish assemblages in temperate marine environments are significantly linked to spatial habitat patterning and seascape complexity. This offers valuable insights into species–habitat–seascape linkages, information important for coastal conservation and marine spatial planning.     

Demersal fish assemblages and spatial diversity patterns in the Arctic-Atlantic transition zone in the Barents Sea

Direct and indirect effects of global warming are expected to be pronounced and fast in the Arctic, impacting terrestrial, freshwater and marine ecosystems. The Barents Sea is a high latitude shelf Sea and a boundary area between arctic and boreal faunas. These faunas are likely to respond differently to changes in climate. In addition, the Barents Sea is highly impacted by fisheries and other human activities. This strong human presence places great demands on scientific investigation and advisory capacity. In order to identify basic community structures against which future climate related or other human induced changes could be evaluated, we analyzed species composition and diversity of demersal fish in the Barents Sea. We found six main assemblages that were separated along depth and temperature gradients. There are indications that climate driven changes have already taken place, since boreal species were found in large parts of the Barents Sea shelf, including also the northern Arctic area. When modelling diversity as a function of depth and temperature, we found that two of the assemblages in the eastern Barents Sea showed lower diversity than expected from their depth and temperature. This is probably caused by low habitat complexity and the distance to the pool of boreal species in the western Barents Sea. In contrast coastal assemblages in south western Barents Sea and along Novaya Zemlya archipelago in the Eastern Barents Sea can be described as diversity "hotspots"; the South-western area had high density of species, abundance and biomass, and here some species have their northern distribution limit, whereas the Novaya Zemlya area has unique fauna of Arctic, coastal demersal fish. (see Information S1 for abstract in Russian).     

Habitat specialization in tropical continental shelf demersal fish assemblages

The implications of shallow water impacts such as fishing and climate change on fish assemblages are generally considered in isolation from the distribution and abundance of these fish assemblages in adjacent deeper waters. We investigate the abundance and length of demersal fish assemblages across a section of tropical continental shelf at Ningaloo Reef, Western Australia, to identify fish and fish habitat relationships across steep gradients in depth and in different benthic habitat types. The assemblage composition of demersal fish were assessed from baited remote underwater stereo-video samples (n = 304) collected from 16 depth and habitat combinations. Samples were collected across a depth range poorly represented in the literature from the fringing reef lagoon (1-10 m depth), down the fore reef slope to the reef base (10-30 m depth) then across the adjacent continental shelf (30-110 m depth). Multivariate analyses showed that there were distinctive fish assemblages and different sized fish were associated with each habitat/depth category. Species richness, MaxN and diversity declined with depth, while average length and trophic level increased. The assemblage structure, diversity, size and trophic structure of demersal fishes changes from shallow inshore habitats to deeper water habitats. More habitat specialists (unique species per habitat/depth category) were associated with the reef slope and reef base than other habitats, but offshore sponge-dominated habitats and inshore coral-dominated reef also supported unique species. This suggests that marine protected areas in shallow coral-dominated reef habitats may not adequately protect those species whose depth distribution extends beyond shallow habitats, or other significant elements of demersal fish biodiversity. The ontogenetic habitat partitioning which is characteristic of many species, suggests that to maintain entire species life histories it is necessary to protect corridors of connected habitats through which fish can migrate.     

Imprint of monsoonal patterns on the fish assemblage in coastal waters of south‐east India: a case study

The composition, species richness and diversity of a coastal fish assemblage from the Kalpakkam coast of south‐east India are described along with temporal distribution patterns related to seasonal fluctuations in dissolved oxygen, salinity, pH, chlorophyll‐a, phytoplankton and zooplankton species richness and density. A total of 244 fish species belonging to 21 orders, 87 families and 163 genera were recorded. The fish assemblage was dominated by reef‐associated species, followed by demersal species. The majority of the species (63%) are widely distributed in the western Indo‐Pacific as well as in the central Indo‐Pacific. Jaccard's coefficient analysis showed three distinct seasonal patterns of fish occurrence: pre‐monsoon (PrM), monsoon (M) and post‐monsoon (PoM). The maximum number of species was during the PrM period, followed by the PoM and M periods. Species occurrence analysis showed Sardinella longiceps to be dominant during PrM and M periods, Leiognathus dussumieri during the M period and Secutor insidiator and Secutor ruconius during the M and PoM periods. Canonical correspondence analysis indicated that salinity and rainfall were the two most influential environmental factors strongly correlated with temporal variation in the fish assemblage. The physico‐chemical conditions, in combination with factors such as greater food availability and shelter, might control the seasonal local distribution of the ichthyofauna in these Indian coastal waters.     

Body size‐dependent responses of a marine fish assemblage to climate change and fishing over a century‐long scale

Commercial fishing and climate change have influenced the composition of marine fish assemblages worldwide, but we require a better understanding of their relative influence on long‐term changes in species abundance and body‐size distributions. In this study, we investigated long‐term (1911–2007) variability within a demersal fish assemblage in the western English Channel. The region has been subject to commercial fisheries throughout most of the past century, and has undergone interannual changes in sea temperature of over 2.0 °C. We focussed on a core 30 species that comprised 99% of total individuals sampled in the assemblage. Analyses showed that temporal trends in the abundance of smaller multispecies size classes followed thermal regime changes, but that there were persistent declines in abundance of larger size classes. Consistent with these results, larger‐growing individual species had the greatest declines in body size, and the most constant declines in abundance, while abundance changes of smaller‐growing species were more closely linked to preceding sea temperatures. Together these analyses are suggestive of dichotomous size‐dependent responses of species to long‐term climate change and commercial fishing over a century scale. Small species had rapid responses to the prevailing thermal environment, suggesting their life history traits predisposed populations to respond quickly to changing climates. Larger species declined in abundance and size, reflecting expectations from sustained size‐selective overharvesting. These results demonstrate the importance of considering species traits when developing indicators of human and climatic impacts on marine fauna.     

Biogeographical structure and affinities of the marine demersal ichthyofauna of Australia

Aim To investigate the biogeographical structure and affinities of the Australian marine demersal ichthyofauna at the scale of provinces and bathomes for the purposes of regional marine planning. Location Australia. Methods Patterns of distribution in the Australian fish fauna, at both intra‐regional and global scales, were examined using a science‐based, management framework dividing Australia’s marine biodiversity into 16 province‐level biogeographical units. Occurrences of 3734 species in eight depth‐stratified bathomes (from the coast to the mid‐continental slope) within each province were analysed to determine the structure and local affinities of their assemblages and their association with faunas of nearby regions and oceans basins. Results Strong geographic and depth‐related structure was evident. Fish assemblages in each province, and in each bathome of each province, were distinct, with the shelf‐break bathome more similar to the adjacent continental shelf bathome than to the upper slope bathome. Data based only on endemic species performed well as a surrogate of the entire dataset, yielding comparable patterns of similarity between provinces and bathomes. Tropical and temperate elements were better discriminated than elements of the Pacific and Indian oceans, with the central western province more similar to the tropical provinces (including those in the east), and the eastern province closer to southern temperate provinces. The fauna shares the closest regional affinities with those of the adjacent south‐west Pacific, western Pacific Rim, and elements of wide‐ranging Indo‐Pacific components. Elements unique to the Pacific and Indian oceans are poorly represented. Main conclusions The complex nature of Australia’s marine ichthyofauna is confirmed. A hierarchy of provinces and bathomes, used to ensure that Australia’s developing marine reserve network is both representative and comprehensive, is equally robust when based on all known Australian fish species or on only those species endemic to this continent. Latitude and depth are more important than oceanic influences on the composition of this fauna at these scales.     

Biophysical factors affecting the distribution of demersal fish around the head of a Submarine Canyon off the Bonney Coast, South Australia

We sampled the demersal fish community of the Bonney Canyon, South Australia at depths (100–1,500 m) and locations that are poorly known. Seventy-eight species of demersal fish were obtained from 12 depth-stratified trawls along, and to either side, of the central canyon axis. Distributional patterns in species richness and biomass were highly correlated. Three fish assemblage groupings, characterised by small suites of species with narrow depth distributions, were identified on the shelf, upper slope and mid slope. The assemblage groupings were largely explained by depth (ρw = 0.78). Compared to the depth gradient, canyon-related effects are weak or occur at spatial or temporal scales not sampled in this study. A conceptual physical model displayed features consistent with the depth zonational patterns in fish, and also indicated that canyon upwelling can occur. The depth zonation of the fish assemblage was associated with the depth distribution of water masses in the area. Notably, the mid-slope community (1,000 m) coincided with a layer of Antarctic Intermediate Water, the upper slope community (500 m) resided within the core of the Flinders Current, and the shelf community was located in a well-mixed layer of surface water (<450 m depth).     

Demersal fish diversity of the isolated Rockall plateau compared with the adjacent west coast shelf of Scotland

This study compares the diversity of the demersal fish assemblage of an isolated shelf sea, the Rockall plateau, with that of the nearest adjacent continental shelf sea ecosystem, the west coast of Scotland. Bottom trawl surveys were carried out between 1986 and 2008 on the Rockall plateau and the adjacent shelf sea to the west of Scotland. All demersal fish were identified and counted. Analyses of species richness and abundance were undertaken. The fish assemblage of the Rockall plateau was less diverse and the proportional representation of species was markedly different. A number of species common at Rockall were rare on the west coast shelf and, in general, there were fewer common and temporally stable species and more rare and ephemeral species at Rockall. Some species absent from Rockall have life‐history stages associated with inshore habitat. The Rockall plateau fish assemblage can be described as an impoverished subset of the north‐west European shelf sea fish assemblage. It is likely that there are constraints on diversity imposed by the relatively small area of the Rockall plateau and its degree of isolation by depth, distance and ocean currents. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 138–147.     

Strengthened currents override the effect of warming on lobster larval dispersal and survival

Human‐induced climate change is projected to increase ocean temperature and modify circulation patterns, with potential widespread implications for the transport and survival of planktonic larvae of marine organisms. Circulation affects the dispersal of larvae, whereas temperature impacts larval development and survival. However, the combined effect of changes in circulation and temperature on larval dispersal and survival has rarely been studied in a future climate scenario. Such understanding is crucial to predict future species distributions, anticipate ecosystem shifts and design effective management strategies. We simulate contemporary (1990s) and future (2060s) dispersal of lobster larvae using an eddy‐resolving ocean model in south‐eastern Australia, a region of rapid ocean warming. Here we show that the effects of changes in circulation and temperature can counter each other: ocean warming favours the survival of lobster larvae, whereas a strengthened western boundary current diminishes the supply of larvae to the coast by restricting cross‐current larval dispersal. Furthermore, we find that changes in circulation have a stronger effect on connectivity patterns of lobster larvae along south‐eastern Australia than ocean warming in the future climate so that the supply of larvae to the coast reduces by ~4% and the settlement peak shifts poleward by ~270 km in the model simulation. Thus, ocean circulation may be one of the dominant factors contributing to climate‐induced changes of species ranges.     

Zoogeography of the coral reef fishes of the Socotra Archipelago

Fish communities and habitats were studied at the Socotra archipelago (Gulf of Aden, ≈12°N 54°E). Extensive and unexpected hermatypic coral communities were recorded, at the centre of a 2200 km gap in knowledge of species and habitat distributions which coincides with a change from a western Indian Ocean coral reef fauna to an Arabian one. The fish assemblage associated with the Socotra archipelago corals is predominantly south Arabian. An east African influence, minimal on the mainland coasts of Arabia, is more evident here, and results in previously unrecorded sympatry between Arabian endemic species and their Indian Ocean sister taxa. A study of distributions of Chaetodontidae (butterflyfishes) in the north-western Indian Ocean reveals a number of distinct patterns, with a trend for species replacement along a track from the northern Red Sea to the Indian Ocean. A major feature of the reef fish zoogeography of the region is found to be a distinct south Arabian area, characterized by a 'pseudo-high latitude effect' which results from seasonal cold water upwelling along the Arabian sea coasts of Yemen and Oman and the Indian Ocean coast of Somalia. This south Arabian feature is consistent across a wide range of fish families. It is most pronounced in Oman and Yemen, and although it is the dominant influence at Socotra it is slightly 'diluted' here by the east African influence. The south Arabian area wholly or partly accounts for most of the major marine zoogeographic features around Arabia, and is the principal feature fragmenting Arabian coastal fish assemblages, and separating them from those of the wider Indo-west Pacific.     

Patterns of distribution for southern Australian marine echinoderms and decapods

Aim To relate patterns of distribution of marine echinoderms and decapods around southern Australia to major ecological and historical factors. Location Shallow‐water (0–100 m) marine waters off southern Australia, south of 30° S. Methods (1) Record the presence/absence of known echinoderm and decapod species in cells of c. 1° latitude and longitude, along the coast of southern mainland Australia and Tasmania. (2) Describe patterns in species composition, species richness and endemism through gradient analysis, ordination and cluster analysis. (3) Relate these patterns to distance and temperature gradients, the area of continental shelf, the average size of species range, and known historical factors. Results Species composition varied with both latitude and longitude. Species richness was relatively constant from east to west but graded with latitude from high in the warm‐temperate regions around Perth and Sydney to low in cool‐temperate southern Tasmania. Species richness was not related to the area of continental shelf or average species range size. Species turnover was not correlated with rates of temperature change. It was problematic to separate distance from temperature gradients, but there was evidence that the southern distribution limits of some species are related to minimum sea surface temperature. Within the taxonomic groups surveyed, evolutionary radiation has been largely limited to a few cosmopolitan species‐rich genera. Main conclusions There are historical as well as ecological hypotheses explaining the latitudinal gradient of marine species richness in southern Australia: (1) the continual invasion and speciation of species of tropical origin as Australia has split from Gondwana and drifted northward; (2) progressive extinction of some Gondwanan cool‐temperate species at the limits of their range; (3) low level of immigration of additional cool‐temperate species; and (4) some in situ endemic speciation.     

The inshore fish faunas over soft substrates and reefs on the tropical west coast of Australia differ and change with latitude and bioregion

Aim To test the following hypotheses regarding ichthyofaunal compositions along an extensive tropical coastline. The compositions over soft substrates and reefs: (1) consistently differ markedly; (2) change progressively with latitude and temperature through sequential changes in the abundances of certain species; and (3) vary among bioregions, as those regions differ markedly in their environmental characteristics. Location Tropical north‐western Australia. Methods Similarity matrices, derived from percentage contributions of each fish species to catches obtained over soft substrates by trawling and over reefs by trapping at seven regularly spaced sites along 1500 km of coast, were subjected to cluster analysis, non‐metric multidimensional scaling ordination and associated tests. Results In total, 361 species were obtained by trawling and trapping along the tropical coast of north‐western Australia (NWA). Only 56 species were recorded over both soft substrates and reefs, whereas 229 and 76 species were caught exclusively over soft substrates and reefs, respectively. The Leiognathidae, Carangidae and Terapontidae contributed most individuals (62.2%) to catches over soft substrates, whereas the Lethrinidae and Lutjanidae dominated those over reefs (81.9%). The species compositions in both habitats were related to latitude and water temperature. Ichthyofaunal compositions in the Kimberley region differed markedly from those in the Canning/Pilbara regions further south, which, in turn, each had distinct characters. The vast majority of species found over both habitats also occur in the Pacific Ocean to the north. Main conclusions The most important fish families over soft substrates and reefs in inshore marine waters of tropical NWA differ markedly. The ichthyofaunal compositions of both habitats undergo similar patterns of progressive change with latitude, due to site‐staggered changes in the relative abundances of key fish species in their respective habitats. Ichthyofaunal composition in both habitats was found to be influenced by water temperature. The latitudinal trends exhibited by species composition are overlaid on a strong bioregional effect, reflecting the influence of the very different environmental conditions in those bioregions, which include marked differences in such factors as tidal regime, turbidity and whether mangroves are nearby. The important contribution of species with a Pacific affinity was presumably facilitated by the polewards‐flowing Indonesian Throughflow, which links the Pacific Ocean with waters bordering the NWA coast.     

Spatial and temporal variations and assemblage structure of fish species in Beymelek Lagoon,Turkey

Spatial and temporal variations and assemblage structure of fish species were investigated in Beymelek Lagoon, on the south‐western Mediterranean coast of Turkey. A total of 3956 fish, mainly juveniles, from 24 species representing 11 families were sampled by gillnets and trammel nets from February 2006 to January 2007. Twelve of the species were marine straddlers, 11 were marine‐estuarine‐dependent and one was catadromous. Numerical contribution of marine‐estuarine‐dependent species to the total fish abundance was 86.2%, while marine straddlers contributed only 13.8%. Despite the higher number of species, the numerical abundance of marine straddlers was lower than the abundance of marine‐estuarine‐dependent species. The contribution of catadromous species by number was only 0.02%. The assemblage was taxonomically dominated by Sparidae (seven species, 51.3%), Mugilidae (five species, 36.0%), and Clupeidae (one species, 10.3%). Among sparids, Sparus aurata, Diplodus sargus and Lithognathus mormyrus contributed 38.0, 7.2 and 4.6% to the total catch, respectively. The most abundant mugilid species was Liza saliens with 25.2%, followed by Chelon labrosus 5.2%, and Liza aurata 4.0%. Contribution by the other mugilid species to total catch was quite low. The Clupeidae (10.3%) were represented by Sardinella maderensis with 9.1% of the total catch. While the upper reaches of Beymelek Lagoon were dominated by Sparus aurata and Liza saliens, dominant in the lower reaches were Sardinella maderensis, Sparus aurata, Diplodus sargus, Lithognathus mormyrus and Liza saliens. Sparids were generally caught from mid‐summer to mid‐winter while mugilids were caught throughout the year. Clupeids occurred mainly from autumn to spring.     

Relationships between the spread of Caulerpa filiformis and fish communities on temperate rocky reefs

The previously sub‐dominant native marine macrophyte Caulerpa filiformis is now dominant on many sub‐tidal rocky reefs in New South Wales (NSW), Australia and is expanding its distribution. As C. filiformis is highly chemically defended and structurally different to co‐occurring habitat‐forming macrophytes, two key attributes that govern fish assemblages, we hypothesized that fish assemblages, particularly herbivorous fishes, would be different at sites where C. filiformis occurred from where it was previously absent and within sites, fish community structure would be correlated to the cover of C. filiformis. We investigated these hypotheses by determining reef‐associated fish assemblage attributes (assemblage structure, species richness, total abundance, Shannon‐Weiner diversity, abundance of herbivorous species) along transects within sites where C. filiformis was present and absent. Surprisingly, despite large patches and very high densities of C. filiformis on the reefs we sampled, at larger spatial scales (i.e., among sites) no fish assemblage metrics differed between sites with large stands of C. filiformis and sites without the alga. Moreover the abundance of one dominant herbivore, the rock cale Aplodactylus lophodon, was greater at sites within large beds of C. filiformis. At smaller spatial scales, however, i.e. within sites where C. filiformis was present, fish assemblages did vary as a function of C. filiformis cover along transects, although this was not consistent across sampling times. Overall, our results suggest that the potential effects of the spread of this alga on faunal communities warrants further investigation.     

Seasonal variability of ichthyoneuston assemblage on the continental shelf and slope of the Southwest Atlantic Ocean,Brazil (20°–23°S)

Many marine organisms spend the early life history stages in neuston domain. Although the importance of ichthyoneuston, few studies were developed in the Southwest Atlantic Ocean. Therefore, this study aimed to improve the knowledge on ichthyoneuston of the Brazilian coast analyzing the vertical stratification and horizontal distribution of these organisms. Neuston samples were collected in daylight between 20°S and 23°S from February to April 2009 (late summer/early autumn; rainy season) and from August to September 2009 (late winter/early spring; dry season). Eggs of six taxa were identified: Anguilliformes, Engraulidae, Clupeidae, Synodontidae, Trichiuridae, and Maurolicus stehmanni (Sternoptychidae). The neustonic larval fish assemblage was composed by 40 families and 63 species. Mullidae and Myctophidae larvae were the most abundant in the rainy period while Mullidae and Mugilidae dominated in the dry season. Seasonal and spatial variation of larval fish assemblages in the neuston were structured by oceanographic features. The larval fish abundance on the outer slope stations may have been favored by the advection of an anticyclone that encompassed most of the study region during the cruise periods. In the rainy season, salinity and local depth structured the larval fish assemblage in a cross‐shelf gradient, while in the dry season the larval assemblage was structured around temperature and north‐south gradient. In the dry season, the cross‐shelf gradient was less pronounced mainly because of the low abundance and frequency of mesopelagic larvae. The low frequency and abundance of some species are probably related to the net avoidance of fish larvae during the day or dial vertical migration, as many species migrate to deeper layers during the day and ascend to neuston only at night. Nevertheless, the present study presented baseline information about the seasonal and spatial variation of the neustonic larval fish assemblage influenced by the oceanographic conditions in the Campos Basin. We recommend to additionally collect night samples to decrease larval escapement rates and to compare night versus day catches to further investigate the influence of daily migration in the neustonic larval fish in the area.     

Significant population structure and asymmetric gene flow patterns amidst expanding populations of Clinus cottoides (Perciformes,Clinidae): application of molecular data to marine conservation planning in South Africa

Clinus cottoides is a fish endemic to the coast of South Africa, predominantly inhabiting rock pools. All South African clinids are viviparous, but probably breed throughout the year; as such, their dispersal may be limited, unlike species with pelagic larval stages. We analysed 343 fish from 14 localities on the west, south and east coasts using two mitochondrial genes and the second intron of the S7 ribosomal gene. Mitochondrial DNA analyses recovered significant genetic differentiation between fish populations from the east coast and other sampling locations, with a second break found between Gansbaai and Cape Agulhas on the south coast. Nuclear DNA recovered shallower, but significant, levels of population structure. Coalescent analyses suggested remarkably asymmetrical gene flow between sampling locations, suggesting that the cold Atlantic Benguela Current and Indian Ocean Agulhas counter‐current play important roles in facilitating dispersal. There was no gene flow between the east coast and the other sites, suggesting that these populations are effectively isolated. Divergence times between them were estimated to at least 68 000 years. Neutrality tests and mismatch distributions suggest recent population expansions, with the exception of peripheral western and eastern populations (possibly a consequence of environmental extremes at the edge of the species distribution). Analyses of the current South African marine protected areas network show that it is not connected and that De Hoop, one of South Africa's largest marine reserves, appears to be an important source population of recruits to both the south and southwest coasts.     

Quantifying Fish Assemblages in Large,Offshore Marine Protected Areas: An Australian Case Study

As the number of marine protected areas (MPAs) increases globally, so does the need to assess if MPAs are meeting their management goals. Integral to this assessment is usually a long-term biological monitoring program, which can be difficult to develop for large and remote areas that have little available fine-scale habitat and biological data. This is the situation for many MPAs within the newly declared Australian Commonwealth Marine Reserve (CMR) network which covers approximately 3.1 million km² of continental shelf, slope, and abyssal habitat, much of which is remote and difficult to access. A detailed inventory of the species, types of assemblages present and their spatial distribution within individual MPAs is required prior to developing monitoring programs to measure the impact of management strategies. Here we use a spatially-balanced survey design and non-extractive baited video observations to quantitatively document the fish assemblages within the continental shelf area (a multiple use zone, IUCN VI) of the Flinders Marine Reserve, within the Southeast marine region. We identified distinct demersal fish assemblages, quantified assemblage relationships with environmental gradients (primarily depth and habitat type), and described their spatial distribution across a variety of reef and sediment habitats. Baited videos recorded a range of species from multiple trophic levels, including species of commercial and recreational interest. The majority of species, whilst found commonly along the southern or south-eastern coasts of Australia, are endemic to Australia, highlighting the global significance of this region. Species richness was greater on habitats containing some reef and declined with increasing depth. The trophic breath of species in assemblages was also greater in shallow waters. We discuss the utility of our approach for establishing inventories when little prior knowledge is available and how such an approach may inform future monitoring efforts within the CMR network.     

Recruitment and growth of two small‐bodied resident fish species (Gobiidae and Atherinidae) in oligohaline,seasonally open lagoons

Spatio‐temporal recruitment patterns, growth and survival of the Swan River goby Pseudogobius olorum and western hardyhead Leptatherina wallacei are described from two small, coastal lagoons on the south coast of Western Australia. In these lagoons, estuarine salinity dynamics were relatively stable over much of the autumn–spring period when freshwater inputs from rivers were reduced and there was no oceanic connection. Preflexion and flexion stages of both fish species contributed strongly to population size structure in downstream reaches, whereas upstream reaches were dominated by postflexion larvae and juvenile stages. Spawning of both species was protracted and largely asynchronous, although the episodic presence of stronger preflexion and flexion cohorts suggested some synchronized spawning had occurred. Comparison with estuarine conditions over this period provided evidence that synchronized spawning may be related to temperature and salinity variations from a combination of freshwater inputs and periods of marine exchange. Uninterrupted growth and the progression of cohorts through to juvenile stages were consistent with the generally stable estuarine conditions. Larval and juvenile stages of both species were also tolerant of abrupt changes in salinity and temperature, which occurred due to a non‐seasonal oceanic connection. These findings were consistent with the euryhaline nature of adults of both species.