Search

Few studies consider spatio‐temporal variation in egg‐laying for benthic insects in streams. However, such variation can have lasting effects on the numbers and distribution of offspring and subsquent life‐cycle stages. For species that require specific egg‐laying habitats, such as rocks that protrude from the water surface (emergent rocks, ER), densities of egg‐laying habitat can affect densities of benthic eggs and even larvae for some species. For such species, changes in water levels alter the spatio‐temporal distribution of ER and can affect densities of eggs and, potentially, larvae. Below dams, modified flow regimes may alter the temporal availability of ER. In this study we tested whether river regulation altered the availability of oviposition habitat and changed the phenology of oviposition compared to unregulated rivers.At multiple sites in two regulated (Murrumbidgee, Tumut) and three unregulated (Goobarragandra, Goodradigbee, Micalong) rivers (south‐east Australia), we surveyed densities of ER and egg masses of five species of caddisflies (family Hydrobiosidae) seasonally over 3 years (2019–2021). Samples of adults also were collected during two seasons using light traps.High flows in both regulated rivers submerged all rocks during spring and summer and low‐flow releases stranded rocks above the waterline at all (Murrumbidgee River) or most (Tumut River) sites during autumn and winter. No ER or egg masses were observed on any date in the Murrumbidgee River, despite relatively large catches of adults. On the Tumut River, low densities of ER and egg masses were twice observed at one site, during seasons (winter, autumn) when oviposition was low in the unregulated rivers.In unregulated rivers, ER and egg masses (five species, four genera) were present at all sites but with lower densities in winter than in other seasons. During peak oviposition periods, densities of egg masses per site were not strongly related to densities of ER. In summer 2019, ER in two unregulated rivers were blanketed by sheets of algae and sediment that appeared to prevent oviposition because no egg masses were observed at this time.In regulated rivers, aseasonal flows precluded egg‐laying by submerging (summer, autumn) or stranding (winter, spring) all or most ER. In contrast, ER were available all year in the unregulated rivers and egg‐laying occurred all year, except when ER were blanketed by algae and sediment. Within seasons, local densities of egg masses may be limited by numbers of gravid females, rather than numbers of ER, which differs from previous research.Identifying impediments to reproduction is critical to understanding variability in population numbers in natural and altered systems. Our observations of oviposition failure downstream of dams present a new hypothesis for why some insect species are absent from channels where flows are regulated for irrigation. Blankets of algae may similarly preclude reproduction in rivers with low‐flow conditions, but this remains untested. [ABSTRACT FROM AUTHOR]

Investigating historical gene flow in species complexes can indicate how environmental and reproductive barriers shape genome divergence during speciation. The processes influencing species diversification under environmental change remain one of the central focal points of evolutionary biology, particularly for marine organisms with high dispersal potential. We investigated genome‐wide divergence, introgression patterns and inferred demographic history between species pairs of all six extant rock lobster species (Jasus spp.), which have a long larval duration of up to two years and have populated continental shelf and seamount habitats around the globe at approximately 40oS. Genetic differentiation patterns reflected geographic isolation and the environment (i.e. habitat structure). Eastern Pacific species (J. caveorum and J. frontalis) were geographically more distant and genetically more differentiated from the remaining four species. Species associated with continental shelf habitats shared a common ancestry, but are geographically distant from one another. Similarly, species associated with island/seamount habitats in the Atlantic and Indian Oceans shared a common ancestry, but are also geographically distant. Benthic temperature was the environmental variable that explained most of the genetic differentiation (FST), while controlling for the effects of geographic distance. Eastern Pacific species retained a signal of strict isolation following ancient migration, whereas species pairs from Australia and Africa, and seamounts in the Indian and Atlantic oceans, included events of introgression after secondary contact. Our results reveal important effects of habitat and demographic processes on the recent divergence of species within the genus Jasus, providing one of the first empirical studies of genome‐wide drivers of diversification that incorporates all extant species in a marine genus with long pelagic larval duration. [ABSTRACT FROM AUTHOR]

Trait‐based approaches are increasingly used as a proxy for understanding the relationship between biodiversity and ecosystem functioning. Macrobenthic fauna are considered one of the major providers of ecosystem functions in marine soft sediments; however, several gaps persist in the knowledge of their trait classification, limiting the potential use of functional assessments. While trait databases are available for the well‐studied North Atlantic benthic fauna, no such trait classification system exists for Australia. Here, we present the South Australian Macrobenthic Traits (SAMT) database, the first comprehensive assessment of macrobenthic fauna traits in temperate Australian waters. The SAMT database includes 13 traits and 54 trait‐modalities (e.g., life history, morphology, physiology, and behavior), and is based on records of macrobenthic fauna from South Australia. We provide trait information for more than 250 macrobenthic taxa, including outcomes from a fuzzy coding procedure, as well as an R package for using and analyzing the SAMT database. The establishment of the SAMT constitutes the foundation for a comprehensive macrobenthic trait database for the wider southern Australian region that could facilitate future research on functional perspectives, such as assessments of functional diversity and changes to ecosystem functioning. [ABSTRACT FROM AUTHOR]

Aim: Mining and petroleum industries are exploring for resources in deep seafloor environments. Lease areas are often spatially aggregated and continuous over hundreds to thousands of kilometres. Sustainable development of these resources requires an understanding of the patterns of biodiversity at similar scales, yet these data are rarely available for the deep sea. Here, we compare biodiversity metrics and assemblage composition of epibenthic megafaunal samples from deep‐sea benthic habitats from the Great Australian Bight (GAB), a petroleum exploration zone off southern Australia, to similar environments off eastern Australia. Location: The Great Australian Bight (34–36°S, 129–134°E) and south‐eastern (SE) and north‐eastern (NE) Australian continental margins (23–42°S, 149–155°E) in depths of 1,900–5,000 m. Methods: A species–sample matrix was constructed from invertebrate and fish megafauna collected from beam trawl samples across regions at lower bathyal (1,900–3,200 m) and abyssal (>3,200 m) depths, and analysed using multivariate, rarefaction and model‐based statistics. We modelled rank abundance distributions (RAD) against environmental factors to identify drivers of abundance, richness and evenness. Results: Multivariate analyses showed regional and bathymetric assemblage structure across the region. There was an almost complete turnover of sponge fauna between the GAB and SE. SE samples had the highest total faunal abundance and species richness. RAD models linked total abundance and species richness to levels of carbon flux. Evenness was associated with seasonality of net primary production. Conclusions: Significant assemblage structure at regional scales is reported for the first time at lower bathyal and abyssal depths in the southern Indo‐Pacific region along latitudinal and longitudinal gradients. The GAB fauna was distinct from other studied areas. Relatively high species richness, previously reported from the GAB continental shelf, did not occur at lower bathyal or abyssal depths. Instead, the abundance, richness and evenness of the benthic fauna are linked to surface primary production, which is elevated off SE Australia. [ABSTRACT FROM AUTHOR]

Abstract The deep sea (> 500 m) of the Great Australian Bight (GAB) has not been well studied even though it is believed to have high conservation values as evidenced by large marine reserves, and where adjacent (continental shelf) waters support important commercial fisheries and large populations of marine mammals. Recent interest in developing the region's deep-sea hydrocarbon resources has drawn attention to this sparsity of data and the need to characterise the region's benthic ecology in order to detect and understand any potential impacts linked to a developing oil and gas industry. To that end, we measured the naturally occurring hydrocarbon content and baseline condition of a variety of benthic fishes and invertebrates collected during two surveys of the continental slope and seabed geological features. A total of 225 individuals, representing 15 species (7 invertebrates and 8 fishes) were analysed for (i) polycyclic aromatic hydrocarbons (PAH) body burdens or biliary PAH metabolites; (ii) 7-Ethoxyresorufin O-deethylase (EROD), a commonly used oil exposure biomarker; and (iii) lipid profiles and histology. Hydrocarbon concentrations, although measurable at some sites, did not indicate any anthropogenic contamination or unequivocal hydrocarbon seepage. PAH body burdens in the invertebrate species were below the levels of detection, and phenanthrene metabolites showed differences between species of fish surveyed, but were consistently low relative to oil exposed fish. EROD levels varied between species but also did not indicate exposure to oil. Lipid levels were highly variable between individuals and sites, suggesting that a lipid-related metric would not be suitable for monitoring organism health. Histological analysis indicated no gross deformity or infection in either the liver, gill, kidney or spleen. Pathologies identified were of minimal pathological important and likely to be recoverable. Liver exhibited varying levels of lipid accumulation across all fish species. These results, obtained before the commencement of oil and gas industry activity, can be used as a part of a baseline benthic ecosystem characterisation to guide future ecological monitoring programs. [ABSTRACT FROM AUTHOR]

Abstract The Great Australian Bight (GAB) is important ecologically due to a diverse benthic fauna with high endemicity, and productivity that supports marine mammals and apex predators. The region is also economically important, supporting valuable fisheries, aquaculture and ecotourism industries. Deep-sea (>200 m depth) exploration leases for oil and gas have also recently been activated. Characterising the environment of the GAB is a priority in light of these activities, but although areas of the GAB continental shelf have been well-studied, there is a paucity of data on benthos from depths > 200 m and a virtual absence of collated benthic ecological information. Predictive ecological modelling is increasingly being used for deep-sea benthic characterisation given the large areas involved and logistic challenges of sampling these environments. For example, species distribution models can be used to predict environmental suitability in unsampled areas, and to inform spatial management for data-poor regions. We explored options and selected the maximum likelihood implementation of the popular MaxEnt method to predict environmental suitability for 96 deep-water benthic species across temperate Australia. Occurrence records were obtained from a collation of historical museum records, online databases and recent sampling in the GAB at 200–3000 m. Aggregated predictions were used to identify patterns of suitability across species. The GAB continental slope had high relative suitability across all modelled species, particularly in the phyla Chordata and Cnidaria, while predicted suitability for species in the phyla Mollusca and Arthropoda was generally higher on the east than south coast of Australia. These patterns were influenced by the suite of species used; we found predicted suitability within the GAB to be negatively influenced by the proportion of east coast records per species. Average bottom temperature, which correlated with depth and a range of water quality variables, was the most important environmental predictor of suitability. The currently poorly-sampled upper mid-slope depths (500–800 m) of the GAB had the greatest predicted suitability across the suite of modelled species; hence recent sampling of the GAB benthos may have underestimated benthic faunal abundance and diversity in this region. [ABSTRACT FROM AUTHOR]

Reef Check Australia (RCA) has collected data on benthic composition and cover at > 70 sites along > 1000 km of Australia's Queensland coast from 2002 to 2015. This paper quantifies the accuracy, precision and power of RCA benthic composition data, to guide its application and interpretation. A simulation study established that the inherent accuracy of the Reef Check point sampling protocol is high (<± 7% error absolute), in the range of estimates of benthic cover from 1% to 50%. A field study at three reef sites indicated that, despite minor observer- and deployment-related biases, the protocol does reliably document moderate ecological changes in coral communities. The error analyses were then used to guide the interpretation of inter-annual variability and long term trends at three study sites in RCA's major 2002–2015 data series for the Queensland coast. [ABSTRACT FROM AUTHOR]

Estuarine ecosystems are considered hotspots for productivity, biogeochemical cycling and biodiversity, however, their functions and services are threatened by several anthropogenic pressures. We investigated how abundance and diversity of benthic macrofauna, and their functional traits, correlate to sediment biogeochemistry and nutrient concentrations throughout an estuarine-to-hypersaline lagoon. Benthic communities and functional traits were significantly different across the sites analysed, with higher abundance and more traits expressed in the estuarine region. The results revealed that the benthic trait differences correlated with sediment biogeochemistry and nutrient concentrations in the system. The estuarine regions were dominated by high abundance of large burrowing and bioturbating macrofauna, promoting nutrient cycling and organic matter mineralisation, while these organisms were absent in the hypersaline lagoon, favouring accumulation of organic matter and nutrients in the sediment. The results highlight the importance of preserving healthy benthic communities to maintain ecosystem functioning and mitigate the potential impacts of eutrophication in estuarine ecosystems. [Display omitted] • Macrofauna, functional traits and sediment biogeochemistry relationship was assessed across an extreme salinity gradient. • Macrobenthic fauna abundance, diversity, and functional traits were lower where hypersaline conditions were recorded. • Macrobenthic trait differences explained correlations with changes in sediment biogeochemistry. • Loss of burrowing and bioturbating macrofauna linked with accumulation of organic matter and nutrients in the sediment. • Outcomes showed that healthy benthic communities mitigate the potential impacts of eutrophication. [ABSTRACT FROM AUTHOR]

Abstract: Western rock lobsters, Panulirus cygnus are an abundant benthic consumer distributed along the temperate west coast of Australia and constitute the largest single species fishery in Australia. As a dominant consumer, it is important to understand their predator–prey interactions as they can potentially exert strong trophic effects, and may influence ecosystem function as seen in other spiny lobster species. While previous field studies have focused on the diet composition of P. cygnus, this study investigated their preference for various benthic invertebrate prey to better understand the likely predator–prey interactions of P. cygnus. Prey preferences of small sub-legal juvenile lobsters, as well as medium and large legal-sized mature lobsters were investigated using laboratory feeding trials to identify size-associated differences in lobster prey preference. Handling time and diet quality were investigated to estimate energetic cost and gain from consuming different prey which may explain prey choice by lobsters. It was found that large lobsters preferred crabs and mussels while medium and small lobsters preferred crabs over mussels, gastropods, and sea urchins. This suggests that strong predator–prey interactions between P. cygnus and crabs may occur in the wild. [Copyright &y& Elsevier]

Abstract: The development of marine benthic communities is strongly influenced by patterns of settlement, recruitment and survival, which may vary across multiple spatial scales in concordance with the scale-dependent processes that drive them. The temperate subtidal reefs off southwest Australia support highly diverse assemblages of macroalgae and sessile invertebrates, yet little is known about spatial variability in the structure of developing assemblages compared with established assemblages. Here, settlement panel arrays were deployed adjacent to subtidal rocky reefs, in 13–15m depth, at 3 locations spanning 400km of temperate coastline in Western Australia. Panel assemblages were allowed to develop for ~14months before they were harvested. Variability in ecological pattern was analyzed at 4 spatial scales, spanning centimeters to 100s of kilometers. The structure of sessile assemblages was vastly different between the 3 locations, in that one location (Geographe Bay) supported an impoverished assemblage comprising a single macrofaunal species whereas assemblages at the other two locations (Jurien Bay and Marmion Lagoon) supported fairly rich assemblages of macroalgae and sessile invertebrates. Multivariate assemblage structure, total richness and total cover varied significantly between the locations, although variability at the smallest spatial scale (centimeters) was consistently pronounced. Variability patterns for key taxa were less consistent across spatial scales. While explanations for the extreme between-location variability remain unclear, there was some evidence to suggest that herbivory by demersal fish may inhibit assemblage development at Geographe Bay, although local hydrodynamic factors (i.e. relatively lower water movement and influence of the dominant regional-scale oceanic current) could also be important. [Copyright &y& Elsevier]

Marine physical and geochemical data can be valuable surrogates for predicting the distributions and assemblages of marine species. This study investigated the bio-environment (surrogacy) relationships in Jervis Bay, a sandy marine embayment in south-eastern Australia. A wide range of co-located physical data were analysed together with biological data, including multibeam bathymetry and backscatter surfaces and derivatives, parameters that describe seabed sediment and water column physical/geochemical characteristics and seabed exposure. Three decision tree models and a robust model selection process were applied. The models for three diversity indices and seven out of eight infaunal species explained 32–79% of the variance. A diverse range of physical surrogates for biodiversity were identified. The surrogates are presented in a conceptual model that identifies the mechanisms that potentially link to biodiversity patterns. While some surrogates may exert direct influence over organisms to exposure and chlorophyll-a, for example, most pointed to complex relationships between multiple biological and physical factors occurring in different process domains/zones. The reliable bio-environment relationships identified from co-located samples and conceptual models enabled a mechanistic understanding of benthic biodiversity patterns in a sandy coastal embayment that may have implications for marine environmental management. [ABSTRACT FROM PUBLISHER]

Photographic line transects were used to quantify the benthic community at Hall Bank, a small, nearshore, high-latitude reef in south-west Australia. On one of the seven transects, the coral cover was 72.5% (mean = 52.6 ± 0.45%), which is the highest ever recorded coral cover at or beyond 32°S. There were no macro-algae, possibly due to the high density of herbivorous sea-urchins (mean = 5.0 ± 0.8 m). Fourteen species of scleractinian corals dominated the benthos, seven of which were from the family Faviidae. Given that Hall Bank is at the limit of environmental tolerance for reef formation, it represents a valuable research opportunity for understanding the factors that build and maintain coral reef biodiversity and resilience. [ABSTRACT FROM AUTHOR]

To investigate potential high organisational level impacts of persistent organic pollution in the wetlands in the Sydney Olympic Park (SOP) remediated site, the benthic macroinvertebrate assemblages of seven wetlands within SOP and two off-site reference wetlands were examined. Sediment cores were collected, stained and preserved from each study site and the macroinvertebrates identified to the appropriate taxonomic level (Class, Order, Family, Subfamily). Data were analysed for taxon richness and macroinvertebrate abundance and multivariate techniques were used to identify chemical/physical characteristics of the sediment, which were important influences on the differences in the assemblage between study sites. Macroinvertebrate abundance was highly variable between study sites and taxon richness was low across all sites. Oligochaetes, nematodes, ostracods and chironomids were the most common taxa found and were the most important in influencing differences between the macroinvertebrate assemblages among the study sites. Sediment grain size and chemical characteristics of the sediments (ΣPAH, ΣPCB, TCDDeq and heavy metal concentrations) were important in separating the study sites based on taxon richness and abundance. Canonical correspondence analysis separated the macroinvertebrate assemblages at newly two created wetlands from those at other study sites including the urban reference sites. Increased sediment POP contamination (particularly as measured TCDDeq and ΣDDT concentrations) is a likely contributor in excluding pollution sensitive taxa and, therefore, alterations to benthic macroinvertebrate assemblages. Further, the influence of TOC suggests the significance of catchment inputs in contributing to changes in macroinvertebrate assemblage. The SOP remediation led to the establishment of wetlands with benthic communities representative of those expected in urban wetlands. [ABSTRACT FROM AUTHOR]

Because the nature, tempo and trajectories of biological changes that follow the cessation of trawling are unknown for seamounts, it is unclear whether closing them to trawling will lead to a recovery of the fauna and, if so, over what time scales. This paper reports on a ‘test of recovery’ from repeated towed camera surveys on three seamounts off New Zealand in 2001 and 2006 (5 years apart) and three off Australia in 1997 and 2006 (10 years apart). In each region, seamounts where trawling had ceased were compared to adjacent seamounts where trawling was still active, and to seamounts that had never been trawled. If recovery signals existed, the likelihood of detecting them was high because the seamounts were relatively small and topographically simple, and because quantitative survey methods were employed. Multivariate patterns showed no change in the megafaunal assemblage consistent with recovery over a 5–10 year timeframe on seamounts where trawling had ceased. Results based on the number of species and diversity were equivocal, with some cases of increase and decrease on seamounts where trawling had ceased. A few individual taxa were found at significantly higher abundance in the later surveys where trawling had occurred. We suggest this may have resulted from their resistance to the direct impacts of trawling (two chrysogorgid corals and solitary scleractinians), or from protection in natural refuges inaccessible to trawls (unstalked crinoids, two chrysogorgid corals, gorgonians, and urchins). Alternatively, these taxa may represent the earliest stages of seamount recolonisation. They have potential to be dominant for long periods because the pre-trawling composition of benthic assemblages on seamounts includes taxa that grow slowly and/or have an association with ‘thickets’ of a single keystone stony coral ( Solenosmilia variabilis) that has generated biogenic habitat over millennia. Resilience of seamount ecosystems dominated by corals is low compared to most other marine systems subject to disturbance by bottom trawling because there are no alternative habitats of the same value for supporting associated species, and because trawling typically removes coral habitat from large areas of individual seamounts. Management to conserve seamount ecosystems needs to account for changing oceanographic conditions (ocean acidification), as well as the direct impacts of human activities such as bottom trawling. Networks of spatial closures that include intact habitats over a range of depths, especially <1500 m, and on clusters and isolated seamounts, may be effective by maintaining the resilience of seamount benthic communities. [ABSTRACT FROM AUTHOR]

Stream food web function is often assessed using carbon stable isotope assessments of the relative contribution of autochthonous and allochthonous sources of organic matter to consumer diets. As a result, variability in source signatures can strongly influence the assessment of carbon flows. To examine the implications of temporal source variability on food web interpretations, benthic algal δ13C signatures were measured over 8 weeks in five streams in subtropical Queensland, Australia. All food webs were largely driven by benthic algal carbon; however, substantial week-to-week variation in benthic algal δ13C signatures modified the calculated contributions of algae to consumer diets, with differences in autochthonous contributions of up to 11% between weeks. In addition, variable algal signatures led to many occasions in which the δ13C signatures of some consumers was beyond the range of available sources, meaning the mixing model analyses did not have a valid solution. Together, these findings suggest that temporal variability in algal δ13C signatures can strongly influence the interpretation of carbon flows in stream food webs. Future food web studies should assess the temporal variability of sources prior to sampling consumers, in order to characterise end member signatures and their relevance to consumers at the time of collection. [ABSTRACT FROM AUTHOR]

Cambrian to Ordovician pelagic radiolarian cherts in the Lachlan Fold Belt in southeastern Australia contain trace fossils demonstrating the faunal diversification that occurred during the Ordovician on the deep-sea floor. The Cambro-Ordovician Howqua Chert has a very low degree of bioturbation, and the trace fossils are small and shallow. In contrast, the late Middle to Late Ordovician cherts are strongly bioturbated with larger, deeper burrows, and contain more morphologically diverse trace fossils. This records a substantial increase in the size, abundance and activity of deep-ocean benthic animals living on the floor of the ocean bordering Australia. [ABSTRACT FROM AUTHOR]

Abstract: At regional scales, the distribution of species and the structure of assemblages vary with latitude within many marine and terrestrial systems. The oligotrophic coastal waters of Western Australia (WA) support highly speciose and endemic assemblages, yet spatial patterns in benthic structure are currently poorly known. We examined benthic assemblage composition along a latitudinal gradient of 28.5–33.5°S and a depth gradient of 14–62m, on subtidal reefs in warm-temperate WA. We surveyed benthos using a remotely triggered digital stills camera. In total, we sampled macroalgae and sessile invertebrates at 201 sites spread across four locations. Percent cover of coarse taxonomic groups and dominant species was estimated from over 2000 photoquadrat samples. We recorded significant differences in benthic assemblage composition between locations, and along depth gradients within each location. However, the magnitude of change with depth was not consistent between locations, and shifts in assemblage composition along the depth gradients were not as pronounced as expected. The percent cover of all dominant benthic groupings differed between locations, and several key taxa, such as the kelp Scytothalia dorycarpa, brown foliose macroalgae, hard corals and sponges, changed predictably along the latitudinal gradient. Our study adopted a coarse taxonomic, but assemblage-wide, approach to describing macrobenthic assemblages, and clear differences between locations and depths were detected. The surveys have provided baseline data on broad scale ecosystem structure against which to detect future ecological change. [Copyright &y& Elsevier]

Large interannual variations in reproductive success caused by fluctuations in oceanography and prey availability are common to many species of air breathing epipelagic predators. In contrast, little is known about variation in benthic foragers such as Australian fur seals ( Arctocephalus pusillus doriferus). Between 1997 and 2007, pup production was assessed in 9 yr, while the timing of breeding and adult female condition was assessed in 5 yr at Kanowna Island in Bass Strait, southeastern Australia. Pup production was variable ( = 1,726 ± 42, range = 1,386–2,301), but without temporal trend, as was median birth date ( = 23 November ± 1, range = 21–25 November) and pupping synchrony (period of 90% births: = 28 ± 2 d, range = 23–31 d). Pup production was negatively correlated with median birth date and positively correlated with female condition, winter sea-surface temperature (SST) and zonal wind strength within Bass Strait. Pup production was also negatively correlated with SST in the previous summer within Bass Strait and in the eastern Great Australian Bight upwelling region. The results suggest that the reproductive success of Australian fur seals is influenced by oceanography but less so than in otariids foraging epipelagically in major upwellings. Despite spanning several El Niño events, no correlation between pup production and the Southern Oscillation Index was observed. [ABSTRACT FROM AUTHOR]

Abstract: The effects of forest harvesting on wet eucalypt forest stream macroinvertebrates were examined in Tasmania, Australia. Sites were selected in second to fourth order streams across a gradient of catchment forest harvesting history and in paired reference catchments. Historical data for every forest parcel (coupe) were obtained for each catchment, detailing forest operational type, area and year of operation, length of roads and number of stream road crossings. We observed substantial differences in macroinvertebrate community composition and abundance across the 14 site pairs. We observed higher abundances of orthoclad midges, Leptophlebiid mayflies and Elmid and Scirtid beetles, and reduced abundances of worms and Notonemourid stoneflies at forestry test sites, than at their paired reference sites. A consistent shift in community composition was observed for 12 of the 14 site pairs. This was accompanied by a shift in functional feeding group representation away from shredders at test compared to reference sites. Community compositional similarity was substantially higher between test than reference sites, with a reduction in community diversity among streams due to a history of upstream forestry. Community dissimilarity between paired test and reference sites was negatively correlated with the average parcel age and time since initial harvesting. We observed declines in abundance with increasing average coupe age of the mayfly family Leptophlebiidae and midge sub-family Chironominae at test sites relative to reference sites. Time since initial disturbance and the number of road crossings jointly accounted for 52% of the variance in paired-site Bray-Curtis dissimilarity values, with both variables negatively correlated with dissimilarity. We observed a shift related to catchment forestry disturbance in macroinvertebrate community composition away from taxa typical of south-east Australian ‘depositional’ headwater stream environments to greater representation of taxa characteristic of higher power, more ‘erosional’ stream reaches. This support the hypothesis of a transition from predominantly degradational responses to forest harvesting operations (in the geomorphological sense) in headwater streams toward transient ‘aggradational’ effects further downstream with concomitant biological responses. [Copyright &y& Elsevier]

The article presents a study which compares the soft-sediment macrobenthic assemblages of those habitat invaded by Caulerpa taxifolia and those which are uninvaded in 2 estuaries in Southern Australia. The result shows that habitat invaded by Caulerpa taxifolia has a less abundant infauna but more abundant of epifauna compared to unvegetated sediment. It reveals that the changes in soft-sediment macroinvertebrate assemblages are caused by an invasion of Caulerpa taxifolia and suggests that infauna are vulnerable to invasion.

Five polymorphic microsatellite loci were developed and then used to assess the population genetic structure of a commercially harvested merobenthic octopus species ( Octopus maorum) in south-east Australian and New Zealand (NZ) waters. Beak and stylet morphometrics were also used to assess population differentiation in conjunction with the genetic data. Genetic variation across all loci and all sampled populations was very high (mean number alleles = 15, mean expected heterozygosity = 0.85). Microsatellites revealed significant genetic structuring (overall FST = 0.024, p < 0.001), which did not fit an isolation-by-distance model of population differentiation. Divergence was observed between Australian and NZ populations, between South Australia and north-east Tasmania, and between two relatively proximate Tasmanian sites. South Australian and southern Tasmanian populations were genetically homogeneous, indicating a level of connectivity on a scale of 1,500 km. Morphometric data also indicated significant differences between Australian and NZ populations. The patterns of population structuring identified can be explained largely in relation to regional oceanographic features. [ABSTRACT FROM AUTHOR]

1. Australian dryland rivers have among the most variable discharge of any rivers worldwide and are characterized by extended periods of no flow during which aquatic habitat contracts into isolated waterholes. Despite naturally high turbidity, benthic primary production is known to be the main source of carbon to waterhole food webs. The objective of this study was to quantify rates of benthic metabolism and identify factors influencing these rates in two Australian dryland rivers, the Cooper Creek and the Warrego River. 2. Both rivers have similar variable hydrology and high levels of turbidity (photic depths < 0.4 m), but fish abundance in Cooper Creek is 10 times than that of the Warrego River. Therefore, an additional aim of the study was to determine if fish abundances reflected underlying differences in benthic primary production. 3. Benthic gross primary production (GPP), benthic respiration, nutrient concentrations and light penetration were measured immediately after flow had ceased (‘post-flow’) and after at least 2 months of zero flow (‘no-flow’) in 15 waterholes from each river. A subset of four waterholes from each river was sampled on two additional occasions to determine if patterns were consistent over time. 4. Cooper Creek generally had higher rates of GPP and a more autotrophic benthic zone than the Warrego River. As a result, the expected positive relationship between fish abundance and GPP was generally observed at a broad catchment scale. 4. Light was the major control in benthic GPP in both rivers, as nutrient concentrations were high on all sampling occasions. However, for similar values of photic depth, GPP was greater in Cooper Creek than in the Warrego River. This suggests that more frequent disturbance of the littoral zone may inhibit biofilm development in waterholes of the Warrego River. 5. Although flow variability in dryland rivers is extreme compared with other rivers worldwide, cycles of expansion and contraction of aquatic habitat in these two rivers were associated with a shift in the dominance of regional scale (subcatchments contributing to river flow) versus local scale (waterhole morphology) influences on ecosystem functioning, similar to floodplain rivers in tropical and temperate regions. [ABSTRACT FROM AUTHOR]

Abstract: The performance of management strategies for a prawn fishery in northern Australia is evaluated using the management strategy evaluation (MSE) approach. The operating model on which the analyses are based includes population dynamics models for four prawn species and five stocks of each species, an effort allocation model and a benthic impacts model. Management is implemented through controls on the fishing effort that targets the two main target species (Penaeus semisulcatus and Penaeus esculentus) and the technical interactions between the two species are also taken into account. The total effort set by management is distributed to regions and grid cells in each region through effort allocation models. The performance measures used in this study cover conservation of the target species, economic returns and the impact of fishing on benthic communities. Two classes of management strategy are evaluated. One class seeks to move stocks towards the target spawning stock size which is a pre-specified fraction of the spawning stock size at which Maximum Sustainable Yield (MSY) is achieved using a threshold control rule, while the other class selects time-trajectories of future effort to maximize discounted profit. Management strategies that control effort levels to maximize the total profit over the long-term outperform those which aim to move the spawning stock size toward S MSY in terms of most performance measures. For example, even when the target stock size for the MSY-based management strategy is selected to be the same as that which maximizes profits, selecting effort to maximize profits leads to lower variability in catches and profits. This study illustrates how broader ecosystem considerations can be included in MSE analyses without the need for the development and implementation of full ecosystem models and hence provides a “middle road” between single-species MSEs and full ecosystem MSEs. [Copyright &y& Elsevier]

1. Large amounts of terrestrial detritus enter many low-order forested streams, and this organic material is often the major basal resource in the metazoan food webs of such systems. However, despite their apparently low biomass, algae are the dominant food of organisms in a number of aquatic communities which conventionally would have been presumed to be dependent on allochthonous detritus, particularly those in the tropics and also in lowland intermittent streams in arid Australia. 2. The dual stable isotope signatures (δ13C and δ15N) of potential primary food sources were compared with the isotopic signatures of common aquatic animals in lowland intermittent streams in south-eastern Australia, in both spring and summer, to determine whether allochthonous detritus was an important nutritional resource in these systems. The isotopic signatures of the major potential allochthonous plant food sources ( Eucalyptus, Phalaris and Juncus) overlapped, but were distinct from algae and the dominant macrophytes growing in the study reaches. The isotopic signatures of biofilm were more spatially and temporally variable than those of the other basal resources. 3. Despite allochthonous detritus having relatively high C : N ratios compared to other potential basal resources, results fromisosource mixing model calculations demonstrated that this detritus, and the associated biofilm, were the major energy sources assimilated by macroinvertebrate primary consumers in both spring and summer. The importance of these energy sources was also reflected in animals higher in the food web, including predatory macroinvertebrates and fish. These resources were supplemented by autochthonous sources of higher nutritional value (i.e. filamentous algae and macrophytes, which had relatively low C : N ratios) when they became more prolific as the streams dried to disconnected pools in summer. 4. The results highlight the importance of allochthonous detritus (particularly from Eucalyptus) as a dependable energy source for benthic macroinvertebrates and fish in lowland intermittent streams of south-eastern Australia. This contrasts with previous stable isotope studies conducted in lowland intermittent streams in arid Australia, which have reported that the fauna are primarily dependent on autochthonous algae. [ABSTRACT FROM AUTHOR]

Abstract: A suite of management options for a prawn trawl fishery in Torres Strait, Australia was assessed for impacts on the benthic fauna using a dynamic management strategy evaluation approach. The specification of the management options was gained through consultation with stakeholders. Data for the model was drawn from several sources: the fleet data from fishery logbooks and satellite vessel monitoring systems, benthic depletion rates from trawl-down experiments, benthic recovery rates from post-experiment recovery monitoring studies, and benthic distribution from large-scale benthic surveys. Although there were large uncertainties in the resulting indicators, robust measures relevant to management were obtained by taking ratios relative to the status quo. The management control with the biggest effect was total effort; reducing trawl effort always led to increases in benthic faunal density of up to 10%. Spatial closures had a smaller benefit of up to 2%. The effect of closing a set of buffer zones around reefs to trawling was indistinguishable from the status quo option. Closing a larger area, however, was largely beneficial especially for sea cucumbers. When the spatial distributions of fauna prior to fishing were accounted for, fauna with distributions positively correlated with effort improved relative to those negatively correlated. The reduction in prawn catch under effort reduction scenarios could be ameliorated by introducing temporal closures over the full-moon period. [Copyright &y& Elsevier]

Eighty-Mile Beach is one of the 10 most populous sites for migratory birds in the Asian-Australasian Flyway. The birds come to Eighty-Mile Beach's tidal mudflats to feed on benthic organisms during their nonbreeding period prior to embarking on a 10,000-15,000-km migration to their breeding grounds in the Arctic. To better understand migratory birds' preferences for areas on the beach, satellite imagery was used to predict grain size and benthic invertebrate distributions. These data were statistically compared with data collected in the field to determine the accuracy of the predictions. Relationships were apparent between compared data, especially in respect to the actual benthic invertebrate distribution. Finally, feeding areas for different bird species were mapped according to where their favored foods would be found. Knowing where the birds should be feeding will help prioritize research and conservation efforts on Eighty-Mile Beach. [ABSTRACT FROM AUTHOR]

A 24 h study of stomach contents and simultaneous sampling of the drift and benthos was used to describe the diet and assess the prey selectivity of Cox’s gudgeon, Gobiomorphus coxii, within a small coastal stream in south-eastern Australia. Prey items consisted entirely of macroinvertebrates with most being ephemeropterans and trichopterans. The greatest number and largest volume of macroinvertebrates were in the stomachs of fish collected just after sunset through until several hours after sunrise. Both the number of empty stomachs and proportion of digested material in the stomach contents peaked at mid-day. Overall, it was concluded that G. coxii was a nocturnal feeder that specialized on benthos, although some evidence of opportunistic prey selection was apparent. Gobiomorphus coxii was also size selective, preferring relatively large prey from both the drift and benthos. [ABSTRACT FROM AUTHOR]

Extreme tidal events are one of the most predictable natural disturbances in marine benthic habitats and are important determinants of zonation patterns in intertidal benthic communities. On coral reefs, spring low tides are recurrent disturbances, but are rarely reported to cause mass mortality. However, in years when extremely low tides coincide with high noon irradiances, they have the potential to cause widespread damage. Here, we report on such an event on a fringing coral reef in the central Great Barrier Reef (Australia) in September 2005. Visual surveys of colony mortality and bleaching status of more than 13,000 corals at 14 reef sites indicated that most coral taxa at wave-protected sites were severely affected by the event. Between 40 and 75% of colonies in the major coral taxa ( Acropora, Porites, Faviidae, Mussidae and Pocilloporidae) were either bleached or suffered partial mortality. In contrast, corals at wave-exposed sites were largely unaffected (<1% of the corals were bleached), as periodic washing by waves prevented desiccation. Surveys along a 1–9 m depth gradient indicated that high coral mortality was confined to the tidal zone. However, 20–30% of faviid colonies were bleached throughout the depth range, suggesting that the increase in benthic irradiances during extreme low tides caused light stress in deeper water. Analyses of an 8-year dataset of tidal records for the area indicated that the combination of extended periods of aerial exposure and high irradiances occurs during May–September in most years, but that the event in September 2005 was the most severe. We argue that extreme low-tide, high-irradiance events are important structuring forces of intertidal coral reef communities, and can be as damaging as thermal stress events. Importantly, they occur at a time of year when risks from thermal stress, cyclones and monsoon-associated river run-off are minimal. [ABSTRACT FROM AUTHOR]

Spatial autocorrelation in ecological systems is a critical issue for monitoring (and a general understanding of ecological dynamics) yet there are very few data available, especially for riverine systems. Here, we report here on assemblage-level autocorrelation in the benthic-invertebrate assemblages of riffles in two adjacent, relatively pristine rivers in south-eastern Victoria, Australia (40-km reaches of the Wellington [surveys in summers of 1996 and 1997] and Wonnangatta Rivers [survey in summer of 1996 only], with 16 sites in each river). We found that analyses were similar if the data were resolved to family or to species level. Spatial autocorrelation was assessed by using Mantel-tests for the data partitioned into different sets of spatial separations of survey sites (e.g. 0–6 km, 6–12 km, etc.). We found strong small-scale (≤6 km) autocorrelation in the Wellington River, which is consistent with known dispersal abilities of many aquatic invertebrates. Surprisingly, there were strong negative correlations at longer distance classes for the Wellington River in one of the two summers (20–40 km) and the Wonnangatta River (12–20 km). That two largely unimpacted, adjacent rivers should have such different autocorrelation patterns suggests that impact assessment cannot assume dependence or independence of sites a priori. We discuss the implications of these results for use of “reference” sites to assess impacts at nominally affected sites. [ABSTRACT FROM AUTHOR]

The aims of this study were to characterize the functional composition of benthic macrofauna of a tropical sea-grass bed and to determine temporal variations in abundance of benthic macrofauna in relation to environmental factors such as sea-grass biomass, temperature, salinity, and sediment type. Benthic macrofaunal composition and abundance were investigated by core sampler during April 1999, October 1999, March 2000, and August 2000 at three stations within a sea-grass bed at Cockle Bay in North Queensland, Australia. A total of 110 species of benthic macrofauna was collected. Polychaetes were the most abundant group (37 species; 52% of total macrofaunal numbers; 47% of biomass) followed by amphipods (27 species; 35% of total numbers). Decapods were also important, with 28 species contributing 31% of total macrofaunal biomass. Other miscellaneous groups were tanaids, isopods, and ophiuroids. Most amphipods (65%) and decapods (90%) were epifaunal, but polychaetes were equally represented by epifauna and infauna. Temporal variation in both species composition and abundance was large: the peak number of benthic macrofauna occurred in April 1999 and March 2000, and biomass was highest in April 1999. Benthic macrofauna numbers as well as biomass were lowest in August 2000. These temporal patterns of abundance of benthic macrofauna appeared to correlate closely with temporal variation of sea-grass biomass. In addition, the factors of life cycle and predation by common fish species may be indirectly associated with these patterns of macrofaunal abundance. [ABSTRACT FROM AUTHOR]

The nature of spatial auto correlation of biota may reveal much about underlying ecological and biological factors responsible for producing those patterns, especially dispersal processes (drift, adult flight, etc.). We report here on assemblage-level autocorrelation in the benthic-invertebrate assemblages (retained in sieves of 300 μm mesh) of riffles in two adjacent, relatively pristine rivers in southeastern Victoria, Australia (40-km reaches of the Wellington and Wonnangatta Rivers). These are related to patterns of autocorrelation in physical and catchment conditions (`environmental variables') in the vicinity of the sampling points. Both the invertebrate assemblages and environmental variables were auto-correlated at small scales (= 8 km) in the Wellington River in one of the sampling years (1996). Dissimilarities of invertebrate assemblages were correlated with dissimilarities of environmental variables in both sampling years (1996 and 1997) in that rivet Environmental variables were auto- correlated in the Wonnangatta River, but this was not expressed as autocorrelation in the assemblages of invertebrates, which were not auto correlated at any scale studied. Individual environmental variables showed different spatial patterns between the two rivers. These results suggest that individual rivers have their own idiosyncratic patterns and one cannot assume that even similar, geographically adjacent rivers will have the same patterns, which is a difficulty for ecological assessment and restoration. [ABSTRACT FROM AUTHOR]

Changes to benthic infauna caused by exploratory gas drilling operations in the Minerva field were examined experimentally using a BACI (before, after, control, impact) design. Analysis of 72 × 0.1 m2 Smith–McIntyre grab samples obtained from one pre-drilling and three post-drilling periods yielded a diverse fauna consisting of 196 invertebrate species and 5035 individuals. Changes to benthic community structure were assessed using ANOVA and nonmetric multidimensional scaling (MDS). The abundances of two common species (Apseudes sp. 1 and Prionospio coorilla) decreased significantly at the well-head site immediately after drilling. The size of these reductions in abundance ranged between 71% and 88%, and persisted for less than 4 months after drilling. A third common species (Katlysia sp. 1) increased in abundance 200 m east of the well-head following drilling. Most species occurred at densities too low to be analysed individually and so were pooled at higher taxonomic levels. Changes in the abundance of species aggregated by phylum varied, but significant declines in the most abundant phyla (Crustaceans and Polychaetes) of 45–73% were observed at all sites within a 100 m radius of the well-head following drilling. In most cases these changes became undetectable four months after drilling following species recruitments. MDS ordinations confirm that drilling related changes to benthic community structure are most pronounced at stations located closest to the well-head. Additionally, the ordinations indicate that modified communities persist at the well-head for more than 11 months following exploratory drilling. [Copyright &y& Elsevier]

Chironomidae larvae often represent a major component of the benthic fauna in inland water bodies and are used frequently as bioindicators of ecosystem health. The genusChironomusis a recognised indicator of organic enrichment and has been used extensively in the northern hemisphere and New Zealand in ecotoxicological studies. However, similar use ofChironomusin Australia is limited due to the presence of cryptic species that restrict the collection of information on species-specific responses to environmental stress. To address the problems associated with species identification, we have used PCR-RFLP of the mitochondrial COI gene to develop DNA profiles for nine common AustralianChironomusspecies. Species-specific haplotypes were identified using reference taxa previously identified by cytological analysis, and verified with field specimens collected from seven wetlands around Melbourne. This research provides an effective tool for species identification of this ubiquitous and often abundant genus that will provide the basis of obtaining species-specific information to inform on the health of aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The infauna at four natural and two constructed tidal flats were sampled to determine differences in assemblages on the southeastern coast of New South Wales, Australia. Spatial variation within location (tidal heights and subsites separated by 50–100 m) and between locations was incorporated into the design to investigate differences in species assemblages between constructed and natural locations. Overall, infauna at constructed locations were intermediate in abundance and species richness, although differences in abundance and species richness across tidal heights were observed at some locations. Multivariate analysis of species composition revealed distinct differences in species assemblages between constructed and natural locations, amongst tidal heights, and considerable spatial variation within any location. Inappropriate design of waterflow at the oldest constructed site is believed to be responsible for the low variability in species assemblages within this location which are characterised by early successional species that occur in disturbed tidal flats. The newer constructed tidal flat appeared to have adequate waterflow, high site variability in species composition and an infaunal assemblage typical of an early successional stage.The importance of measuring spatial variability in monitoring is stressed in order to make useful comparisons between constructed and natural tidal flats. This study showed that the successful construction of a mature and healthy tidal flat requires the maintenance of a significant waterflow area to ensure adequate tidal flow for the establishment of fauna. [Copyright &y& Elsevier]

The soft-bottom benthic macrofauna in a spoil-ground of dredged material in Cleveland Bay, North Queensland, Australia, was studied to detect possible impacts of the disposal of sediments. The spatial distribution of the assemblage was studied in relation to the source of the impact at 28 stations on four occasions during 1998 and 1999. Additionally, environmental variables were measured on each occasion at each station. Macrobenthic assemblages inside the spoil-ground were different from assemblages outside the spoil ground only immediately after (15 days) the disposal of dredged material. Given the decrease in the abundance of organisms and number of species, it is suggested that this effect was due to direct burial of the macrobenthic assemblage inside the spoil-ground. Macrobenthic assemblages inside the spoil ground were not different from assemblages outside the spoil ground 3 months after dumping. These results suggest that the soft-bottom macrobenthic assemblages may respond quickly to the disturbance associated with the dumping of dredged material. [Copyright &y& Elsevier]

Variation in the structure of shallow subtidal invertebrate assemblages was examined over three spatial scales; within reef, between reef and between continents. We sought to provide a context from which to examine and interpret ecological processes between continents. In addition, we predicted that variation in pattern would increase as the scale of examination increased. Reefs near Wollongong and within Jervis Bay in south-eastern Australia and Mediterranean reefs on the Costa Brava (Catalonia), north-eastern Spain. We compared assemblages on vertical rock walls of two heights – short (< 2 m) and tall (> 3 m) in two temperate regions over the same depth range. Specifically we examined the diversity and cover of invertebrates, the cover and biomass of foliose and crustose algae, the size of invertebrate colonies and the biomass of urchins on short and tall walls ( n = 3) at each of two locations in each country. Foliose algae dominated rock walls in Spain and although invertebrate cover was high, colonies were generally very small. Two urchin species were commonly encountered on rock walls in Spain, Arbacia lixula and Paracentrotus lividus; their biomass was relatively low and did not differ significantly between short and tall walls. These findings contrasted strongly with south-eastern Australia, where foliose algae were almost completely absent. A single urchin species, Centrostephanus rodgersii occurred with extremely high biomass on short walls, which were dominated by grazer-resistant crustose calcareous algae. In contrast, the biomass of this urchin was low on tall walls, which were dominated by invertebrates, usually exceeding 95% in cover. Invertebrate colonies were significantly larger on both short and tall walls in south-eastern Australia relative to the Mediterranean. Findings within a country were consistent between the replicate rock walls and between locations. In contrast to our prediction, however, there was significant variation among walls within a location, but not among locations within a continent. Temporal variation in the structure of these assemblages was not examined, but appears limited. We conclude that submarine topography, i.e. the presence of short or tall rock walls, as a function of rock type and structure, has a marked impact on community structure in south-eastern Australia, but made little difference to the structure of the assemblage in Mediterranean Spain. The differences in structure we observed between walls of different heights in Australia were correlated with differences in the biomass of urchins and they appear to be major determinants of assemblage structure. Interactions among species are often reported from disparate parts of the globe with little or no reference to the structure of the assemblage of which they are a part; we contend that this will hinder interpretation. Our data are consistent with the organisms in these two regions experiencing distinct selection pressures; for example high levels of urchin grazing activity in south-eastern Australia, and shading and whiplash associated with an algal canopy in the Mediterranean. It may not be appropriate to contrast processes operating at very large (intercontinental) scales unless context can be established with a clear understanding of ecological pattern. [ABSTRACT FROM AUTHOR]

SUMMARY 1. We examined the effect of the exotic macrophyte, para grass (Urochloa mutica ), on benthic and epiphytic macroinvertebrates of a tropical floodplain in northern Australia. Macroinvertebrates were sampled from four grass communities: (1) para grass, (2) hymenachne (Hymenachne acutigluma ), a native perennial; (3) rice (Oryza meridionalis ), a native annual, and (4) areas where para grass had been sprayed with herbicide. 2. Macroinvertebrate richness, abundance and community similarity showed very few differences among the grass communities, particularly in the epiphytic habitat. Benthic invertebrates showed some differences among grasses, with lower richness and abundance and different community structure associated with hymenachne. Herbicide control of para grass had no apparent effect on benthic invertebrates but reduced the abundance of epiphytic invertebrates in the short term. 3. The results of this study indicate that para grass has very little impact on macroinvertebrate communities, despite the changes to macrophyte communities. This is probably because para grass has similar physical structure to the native grasses and because none of these grasses contribute directly to aquatic food webs. Control of para grass using herbicide has little impact on aquatic invertebrates. This suggests that predicting the impact of weed invasion in wetlands requires an understanding of both the functional properties of macrophytes and the habitat preferences of the macroinvertebrates. [ABSTRACT FROM AUTHOR]

This research examines the foraging energetics and diving behavior of the Australian sea lion, Neophoca cinerea. We examine whether the foraging ecology of the Australian sea lion is typical for an animal that has evolved to exploit benthic habitats. Such a strategy is in marked contrast to those utilized by some seabirds and other pinnipeds that feed in the midwater, where travel and search components of the time at sea become more important. Onshore and at-sea field metabolic rates (FMR) were measured using doubly labeled water in lactating sea lions at Kangaroo Island, South Australia, during the winter of 1988 (early lactation, breeding season 1) and the summer of 1990 (early lactation, breeding season 2). Dive behavior was also measured with dataloggers during these seasons, as well as in the summer of 1991 (late lactation, breeding season 2). The foraging behavior of Neophoca cinerea indicated that it works hard to exploit benthic habitats in the waters around its breeding site. Sea lions maximized time spent at or near the benthos, with 61% of each dive and 35% of their time at sea being spent at the deepest 20% of the dives. The dive pattern was characterized by almost continuous diving when at sea, with 57.9% of their time at sea spent at depths ≥6 m, and dive rates of 10.7 dives/h. Mean surface intervals (1.0-1.9 min) accounted for only 42% of mean dive durations (2.2-4.1 min). Mean dive depths ranged from 41.5 m to 83.1 m, with maximum dives ranging from 60 m to 105 m. The energetic costs of this strategy are high when compared with those of other otariids: the mean at-sea FMR was 7.05 ± 0.99 W/kg. We report seasonal variability in foraging energetics and dive behavior that is likely to be sensitive to regional oceanography, the maintenance costs of female sea lions and their offspring, and the distribution and behavior of their prey. Further, we note that Australian sea lions are functionally adapted to benefit from benthic foraging... [ABSTRACT FROM AUTHOR]

The ability of benthic macrofauna to disperse and colonize new habitats throughout their life may contribute substantially to small-scale patchiness in abundances in different habitats. Microgastropods in coralline turf on rocky shores in Australia are very patchy in abundance at different spatio-temporal scales. They therefore represent an ideal assemblage for testing hypotheses about processes of colonization. Patterns and rates of colonization of 10 species of microgastropods were investigated in one intertidal habitat (coralline turf) in Botany Bay, New South Wales, Australia, using artificial substrata, which are considered to be a good mimic of natural coralline turfs. The experiment was designed to test the hypotheses that (1) patterns (abundance of colonizing individuals) and mode (juveniles vs. adults) of colonization depends on the proximity of a patch to a potential source of dispersing colonists (i.e. patch of natural coralline turf), (2) different species show different rates of colonization, and (3) patterns of succession are not repeatable among different patches of natural algae. Seven different plots (natural patches of coralline turf) were randomly chosen in the area of study. Artificial units (called patches) were placed at different distances around each plot (within the plot and 0, 50 or 100 cm away from the edge). Samples were collected 6, 13, and 27 days after the experiment started. Colonization was rapid (i.e. within 6 days) for most species. Pattern (number of individuals) and mode of colonization (adults vs. juveniles) varied among algal plots. Most species responded differently across patches causing no consistent patterns of colonization. Furthermore, patterns of colonization of artificial units were not always synchronous with, or in the same direction as, changes in abundances in the nearest algal plots, which themselves showed no consistent spatio-temporal pattern. [Copyright &y& Elsevier]

A survey of the benthic infauna (macro- and mesofauna) in tidal flats of Hinchinbrook Channel, north-east Australia, was carried out to assess the species diversity and individual abundances as well as their temporal variations. Two sites were surveyed at five occassions from November 1988 to October 1991. In addition, spatial distributions over the intertidal gradient were investigated once in May 1990. During the entire survey, over 200 species were recorded, with 53 species found on average at each sampling occassion. Species densities ranged from 4.0 to 8.2 species 177 cm-2 for macrofauna and from 4.1 to 11.8 species 10 cm-2 for mesofauna, but varied little between sites. The average infaunal diversity (H') was 2.53. Individual abundances reached median values of 14.0 individuals 177 cm-2 for macrofauna and 14.5 individuals 10 cm-2 for mesofauna. Changes in total abundances were not related to season and inconsistent at the two study sites, with significantly higher abundances occurring either at site A or B on single sampling dates. Transects sampled in May 1990 showed varying species compositions and abundances in the upper, mid and lower intertidal, but no defined benthic communities were revealed by multivariate analyses. Temporal variations in the benthic assemblages of the two tidal flats in Hinchinbrook Channel were higher than variations between sites, with a separation of assemblages before and after 1989. Problems to assess and interpret temporal changes in species rich tropical benthic communities are discussed. [ABSTRACT FROM AUTHOR]

Focuses the implementation of a stream biological monitoring programs using benthic invertebrates in all States and Territories of Australia. Adoption of a rapid bioassessment approach from specified habitats at the site; Interaction of taxonomic resolution with sample size; Variation of rock size both within and between sites.

Every year >100 killer whales accumulate on the continental slope near Bremer Bay in the western Great Australian Bight from late austral spring to early autumn (January–April), which can be regarded as a natural wonder. For unknown reasons, the whales tend to feed in the same confined region over a seafloor plateau near the head of the Hood Canyon, where the total water depth is ~800–1000 m. The hypothesis behind this work is that the killer-whale aggregation is the signature of a localized marine food web originating from flow-induced upwelling and concentration of benthic particulate organic matter (POM). To test this hypothesis a hydrodynamic model is applied to analyse the pathways of virtual suspended particles released near the seafloor in three large submarine canyons that exist in the region. Here we show that, due to its shape and positioning on the continental slope, the Hood Canyon operates to funnel significantly more benthic particles onto the ambient continental slope than the adjacent Bremer Canyon and the Whale Canyon. Moreover, findings suggest that smaller-scale topographic undulations within the Hood Canyon are the cause of this slope upwelling of POM. This transport mechanism of POM may explain the ecological uniqueness of the region. • Explores that current-induced upwelling and trapping of particulate organic matter (POM) in slope-confined submarine canyons. • Compares POM fluxes in three different canyons in the Bremer Sub-Basin, western Great Australian Bight, Australia. • Finds that the Hood Canyon operates are a bottleneck for such POM fluxes. • This concentration of POM explains the feeding aggregation of killer whales. [ABSTRACT FROM AUTHOR]

Patterns of co-occurrence of benthic macroinvertebrates across different habitat patches were monitored for 1 year at one site on the Acheron River, Victoria. 2. There was a gradual transition in community structure between erosional and depositional habitat extremes. The correspondence between faunally defined sample groups and habitats was not exact. 3. Seasonal changes in community pattern were demonstrated only for erosional habitats. Again the transition was gradual rather than abrupt and contrasted sharply with data from more severe hydrological regimes. 4. Most of the community pattern was conferred by a minority of the species present. These species generally had special requirements that apparently could be satisfied only by being confined to the surface layer of sediments. [ABSTRACT FROM AUTHOR]

Background: Our knowledge of the benthic fauna at lower bathyal to abyssal (LBA, > 2000 m) depths off Eastern Australia was very limited with only a few samples having been collected from these habitats over the last 150 years. In May–June 2017, the IN2017_V03 expedition of the RV Investigator sampled LBA benthic communities along the lower slope and abyss of Australia's eastern margin from off mid-Tasmania (42°S) to the Coral Sea (23°S), with particular emphasis on describing and analysing patterns of biodiversity that occur within a newly declared network of offshore marine parks. Methods: The study design was to deploy a 4 m (metal) beam trawl and Brenke sled to collect samples on soft sediment substrata at the target seafloor depths of 2500 and 4000 m at every 1.5 degrees of latitude along the western boundary of the Tasman Sea from 42° to 23°S, traversing seven Australian Marine Parks. Results: The biological sampling included 35 beam trawls, 28 Brenke sleds, 8 box cores, 20 surface meso-zooplankton tows, and 7 Deep Towed Camera transects. In total, 25,710 specimens were identified to 1084 taxonomic entities, including 847 species-level, 144 genus-level and 69 family-level and 24 higher-level taxa. Of the species-level taxa, only 457 were assigned species-level taxonomic names, which implies that up to 58% of the collected fauna is undescribed. In addition, the ranges of numerous species have been extended to include the western Tasman Sea. Conclusions: The lower bathyal and abyssal fauna of soft sediment seafloors off eastern Australia has been systematically surveyed for the first time. The resultant collections will provide the foundation for much future ecological, biogeographical, phylogenetic and taxonomic research. [ABSTRACT FROM AUTHOR]

Many rigorous methods have been developed to manipulate and sample rocky benthic species, but development of field methodology is less advanced for disturbance-prone rocky habitats e.g. cobbles and boulders. These habitats can have ecological and economic importance but research is complicated by their complex physical structure that necessitates causing disturbance when sampling, possibly resulting in mobile species being lost from samples. We used simulated/controlled sampling conditions to determine the proportions of mobile species successfully captured or lost during sampling. Boulders and cobbles were lifted out of shallow water (i.e. "littoral" sampling) and sampled in simulated sublittoral conditions, targeting biota attached to the undersurfaces. Variation in sample losses associated with different methods was tested – sampling in shallow vs deep water and small vs large boulders/cobbles. Different species and locations were also compared. Tests were done to determine contexts producing minimal losses and thus deserving prioritisation. Experiments were replicated in southern Australia and NE Baltic Sea. Large proportions of littoral amphipods and isopods were not successfully captured during sampling in most contexts (overall mean loss = 35%). This means lifting boulders from shallow water cannot accurately sample them. This finding is important especially for highly researched boulder or cobble associated invasive amphipods with large ecological impacts. Seventeen percent of littoral gastropods were lost from samples in both regions; in Australia greater proportions were occasionally lost when sampling larger boulders. Chitons and one gastropod (Theodoxus fluviatilis) could be sampled from shallow water with consistently high reliability. During sublittoral sampling, mean sample loss was 13% with no significant interspecific variability. Boulder/cobble size and water depth rarely caused influence. The results reveal sampling contexts where more sophisticated methods may be used for highly accurate abundance measurements in recent research programmes of ecological restoration and conservation of rare species involving marine but also freshwater habitats. Unlabelled Image • Coastal boulder and cobble reefs often have ecological and economic importance • Littoral sampling disturbance caused loss of many peracarids but fewer molluscs • For sublittoral sampling 13% of samples were lost with no interspecific variability • Water depth and boulder/cobble size rarely caused influence on sample loss rates • The results inform sampling methodology for marine conservation and restoration [ABSTRACT FROM AUTHOR]

The biogeography of the deep-sea benthic fauna is uncertain due to the vast size and incomplete exploration of these environments. While shallow water assemblages are differentiated into tropical, temperate and polar faunas, it is unknown whether these units extend to lower depths. Here we use model-based and multivariate statistics to analyse megafaunal benthic samples along a 2300 km transect off the eastern Australian continental margin. We show that a temperate-tropical transition between 33-30°S occurs at both lower bathyal (~2500 m) and abyssal (~4000 m) depths. This transition occurs despite almost uniform temperature, salinity and dissolved oxygen concentrations occurring across latitudes at these depths. Conversely, the patterns are consistent with the flux of organic matter to the seafloor, which varies from being relatively high in the productive temperate off SE Australia to low levels in more-oligotrophic tropical waters. Biodiversity is not uniform across the deep-sea and regional-scale heterogeneity needs to be incorporated into marine park designs. • There is a significant temperate-tropical transition in benthic assemblages at bathyal-abyssal depths off eastern Australia • The transition is congruent with variation in net primary productivity but not gradients of temperature, salinity or oxygen • The deep-sea habitats are not uniform and assemblage composition differs at regional scales [ABSTRACT FROM AUTHOR]

An Australian estuary is primarily a marine-dominated environment, subjected to major salinity changes only after heavy rains and during flood conditions. In southeastern Australia estuarine biota are similar to those in shallow coastal bays and some of the coastal lagoons, and most taxonomic studies on estuarine fauna have occurred in this region. Several major surveys of estuarine and coastal bays have been undertaken in Australia during the past three decades and these surveys have largely provided the material for taxonomic studies of the major groups of macrobenthos. All these studies have revealed a diverse and abundant benthic macrobenthos. The composition of estuarine invertebrate fauna is compared with open exposed coasts, including fauna found in soft strata and on hard strata. Australia has a limited specialized estuarine biota much of which is restricted to particular habitats, and a highly diverse marine community which thrives in the sheltered protected waters of estuaries and the associated soft sediments. Currently, interactive computer-based keys are being developed which should greatly assist the student and the benthic ecologist to identify the fauna and prevent potential loss of data. Some aspects of the current debate of the level of taxonomic resolution required to answer various ecological questions are discussed. Finally, some comments are suggested as to future directions in which taxonomists and estuarine ecologists should proceed in order to be able to detect changes or losses of estuarine biodiversity and the loss of the associated biological information which may be critical in understanding the functioning of the estuarine ecosystem. [ABSTRACT FROM AUTHOR]