Key ecological features (KEFs) are elements of Australia’s Commonwealth marine environment considered to be important for biodiversity or ecosystem function, yet many KEFs are poorly researched, ...which can impede effective decision-making about future development and conservation. This study investigates a KEF positioned over the Last Glacial Maximum (LGM) shoreline on the northwest shelf of Australia (known as the ‘Ancient Coastline at ~125m depth contour’; AC125). Seafloor bathymetry, sedimentology and benthic habitats were characterised within five study areas using multibeam sonar, sediment samples and towed video imagery. Direct evidence for the existence of a palaeoshoreline formed during the LGM was not found, however candidate areas to find palaeoshoreline material at or just below the modern seabed were discovered. Approximately 98% of the seabed surveyed was comprised of unconsolidated soft sediment habitat (mud/sand/silt) supporting negligible epibenthic biota. The prevalence of soft sediment suggests that post-glacial sediments have infilled parts of the palaeoshoreline, with cross-shelf, probably tidal currents in the northern section of the study area responsible for some of the sediment mobilisation and southern study areas more influenced by oceanic conditions. Within study areas, total biotic cover ranged from 0.02% to 1.07%. Of the biota encountered, most comprised filter feeder organisms (including gorgonians, sponges, and whip corals) whose distribution was associated with pockets of consolidated hard substrate. Benthic community composition varied with both study area and position in relation to the predicted AC125. In general, consolidated substrate was proportionally higher in water shallower than the AC125 compared to on the AC125 or deeper than the AC125. Spatially continuous maps of predicted benthic habitat classes (pre-determined benthic communities) in each study area were developed to characterise biodiversity. Spatial modelling corroborated depth and large-scale structural complexity of the seafloor as surrogates for predicting likely habitat class. This study provides an important assessment of the AC125 and shows that if a distinct coastline exists in the areas we surveyed, it is now largely buried and as such does not provide a unique hard substrate habitat. However, much work remains to fully locate and map the ancient coastline within the vast region of the AC125 and additional surveys in shallow waters adjacent to the AC125 may identify whether some sections lie outside the currently defined KEF.
The silver-lipped pearl oyster,
Pinctada maxima
, is the primary species used for the culture of pearls in the Indo-Pacific region. The Western Australian fishery relies on wild-caught animals, and ...as such, knowledge of the status and distribution of
P. maxima
underpins sustainable management of the fishery. Eighty Mile Beach, in tropical Western Australia, is the key harvest area for
P. maxima
, with oysters collected by divers to depths of ∼35 m, although there are anecdotal accounts of oysters beyond diving depths. Image-based, and acoustic methods were used to elucidate distribution patterns of
P. maxima
off Eighty Mile Beach, including data from 862 km
2
of multibeam survey and 119 towed video transects spanning an area from the 20 to 100 m contour lines. We quantified habitat characters including depth, substrate, and benthic community composition associated with pearl oyster distribution. Multibeam sonar data was also coupled with towed video data to produce predictive statistical models of
P. maxima
habitat. We found
P. maxima
to depths of 76 m, although more than 90% of individuals occurred shallower than 40 m and less than 2% were found deeper than 50 m. Oysters occupied flat, sandy habitats with neighbouring benthic communities of filter feeders (>98% of observations). These results show
P. maxima
predominantly occurs in depths <40 m, with no evidence that extensive populations extend into deep water in the region.
Coral communities were monitored at Pandora Reef, nearshore Great Barrier Reef from 1981 to 2005 using photography and videography. In the 1980s, regional elevation of land-based nutrients in coastal ...waters (ca. 2-6 times pre-European levels of early 1800s) did not prevent overall recovery of coral cover and diversity following a sequence of environmental disturbances in the 1970s. However, prospects for a repeat of such resilience following catastrophic mortality from high-temperature bleaching in 1998 and a cyclone in 2000 are not clear. Different coral communities around the reef varied greatly in relation to impacts and recovery. Fore-reef communities dominated by acroporids (fast growing branching and tabular Acropora and foliose Montipora) recovered strongly in the 1980s following apparently severe impacts by cyclone, flood and heat wave disturbances in the 1970s, attaining 60-90% cover by stabilizing rubble and outgrowing macro-algae in <10 years. In the back-reef, by contrast, poritid-dominated communities (massive and finger Porites and columnar Goniopora and Alveopora) had more stable trajectories and smaller impact from recent disturbances: recovery was well underway in 2005. The contrasting trajectories of different parts of the reef reflect differential survival of more persistent versus more ephemeral taxa, notably poritids and acroporids, respectively, both major contributors to framework and cover on reefs globally. A repeat of earlier resilience appears possible in the shallow fore-reef, but unlikely in the deeper fore-reef, which had few viable fragments or recruits in 2005. The main limits on recovery may be (1) reduced supply of coral larvae due to widespread regional losses of coral brood stock and (2) the reduced intervals between disturbances associated with global climate change. The presence of a high abundance of Acroporidae is a major pre-disposing risk factor for climate change impacts.PUBLICATION ABSTRACT
Box jellyfish cause human fatalities and have a life cycle and habit associated with shallow waters (<5 m) in mangrove creeks, coastal beaches, embayments. In north-western Australia, tow video and ...epibenthic sled surveys discovered large numbers (64 in a 1500 m tow or 0.05 m(-2)) of Chironex sp. very near to the benthos (<50 cm) at depths of 39-56 m. This is the first record of a population of box jellyfish closely associated with the benthos at such depths. Chironex were not widespread, occurring only in 2 of 33 tow videos and 3 of 41 epibenthic sleds spread over 2000 km(2). All Chironex filmed or captured were on low to medium relief reefs with rich filter feeder communities. None were on soft sediment habitat despite these habitats comprising 49% of all sites. The importance of the reef habitat to Chironex remains unclear. Being associated with filter feeder communities might represent a hazard, and other studies have shown C. fleckeri avoid habitats which represent a risk of entanglement of their tentacles. Most of our observations were made during the period of lowest tidal current flow in the morning. This may represent a period favourable for active hunting for prey close to the seabed.
The study was conducted to improve knowledge and provide guidance on reducing uncertainty with impact predictions when drilling near sensitive environments. Near/Far-field hindcast modelling of ...cuttings/drilling fluid (mud) discharges from a floating platform was conducted, based on measured discharge amounts and durations and validated by ROV-based plume and seabed sampling. The high volume, concentration, and discharge rate water-based drilling mud discharges (mud pit dumps) were identified as the most significant dispersal risk, but longer-range movement was limited by the generation of jet-like plumes on release, which rapidly delivered muds to the seabed (80 m). Effects to the sparse benthic filter feeder communities close to the wells were observed, but no effects were seen on the epibenthic or demersal fish assemblages across the nearby mesophotic reef. For future drilling near sensitive environments, the study emphasized the need to better characterise drilling fluid discharges (volumes/discharge rates) to reduce uncertainty in modelling outputs.
Abstract
Although emergent coral reefs represent a significant proportion of overall reef habitat, they are often excluded from monitoring projects due to their shallow and exposed setting that makes ...them challenging to access. Using drones to survey emergent reefs overcomes issues around access to this habitat type; however, methods for deriving robust monitoring metrics, such as coral cover, are not well developed for drone imagery. To address this knowledge gap, we compare the effectiveness of two remote sensing methods in quantifying broad substrate groups, such as coral cover, on a lagoon bommie, namely a pixel‐based (PB) model versus an object‐based (OB) model. For the OB model, two segmentation methods were considered: an optimized mean shift segmentation and the fully automated Segment Anything Model (SAM). Mean shift segmentation was assessed as the preferred method and applied in the final OB model (SAM exhibited poor identification of coral patches on the bommie). While good cross‐validation accuracies were achieved for both models, the PB had generally higher overall accuracy (mean accuracy PB = 75%, OB = 70%) and kappa (mean kappa PB = 0.69, OB = 0.63), making it the preferred method for monitoring coral cover. Both models were limited by the low contrast between Coral features and the bommie substrate in the drone imagery, causing indistinct segment boundaries in the OB model that increased misclassification. For both models, the inclusion of a drone‐derived digital surface model and multiscale derivatives was critical to predicting coral habitat. Our success in creating emergent reef habitat models with high accuracy demonstrates the niche role drones could play in monitoring these habitat types, which are particularly vulnerable to rising sea surface and air temperatures, as well as sea level rise which is predicted to outpace reef vertical accretion rates.
As some types of disturbance to coral reefs are attenuated with depth, the resilience of herbivorous fish species utilizing shallow areas (< 30 m) is likely enhanced if their population footprint ...extends into adjacent deeper reef areas. Using field surveys from an isolated coral reef, off northwest Australia, we created data-driven models relating herbivorous fish communities to habitat across an extended depth range (4–76 m). Models assessed variations in functional redundancy across depth to test if the ecological functions provided by herbivores at shallow reefs can be replenished by deep water populations. Eighty percent of herbivorous species (1967 fishes, 48 species total) were associated with depths < 30 m, where hard coral was the dominant benthos (peak diversity ~ 20 m). Some species were restricted to shallow reef (< 30 m), while others were ubiquitous (4–70 m), or most abundant in deeper reef (30–70 m). Functional diversity and redundancy were highest at < 30 m, almost 2 × higher than for deeper (> 30 m) reef areas. Scraper herbivores were associated with the reef crest (< 10 m), grazers with the reef slope (< 30 m), and browsers were evenly distributed across depth (4–70 m). Impacts to herbivores in shallow reefs (e.g. ocean warming, storms, fishing) may be ameliorated if species are widely distributed across depth, or have the ability to opportunistically relocate to adjacent undisturbed areas. Deeper habitat appears to support a subset of the herbivore community, by providing habitat and resources for the browser functional group (only herbivores capable of ingesting large macroalgae) and species with generalist depth distributions and known trophic flexibility (e.g. genus
Scarus
). Additional management of depth zones where functional group distributions overlap may maximize chances of sustaining herbivore diversity and functional redundancy, and provide enhanced protection across depth for important fished species such as large parrotfishes and unicornfishes.
In pre-clinical models of marijuana abuse, there is relatively limited evidence of delta-9-tetrahydrocannabinol's (THC) rewarding effects, as indexed by its general inability to induce a place ...preference. One explanation for this failure is that its rewarding effects are masked by its concurrently occurring aversive properties. Consistent with this explanation, THC pre-exposure, which presumably weakens its aversive effects, induces place preferences. Such demonstrations are limited to mice and given reported species differences in THC reactivity, it is unknown to what extent the same shift in affective properties would be evident in rats.
The present experiment examined the effect of THC history (3.2mg/kg) on THC (1 or 3.2mg/kg) induced place preference conditioning in rats. An assessment of taste avoidance was also run to independently characterize THC's aversive effects and any changes that occurred with drug pre-exposure. These assessments were made in a combined taste avoidance/place preference procedure in which a novel saccharin solution and environment were paired with THC (0, 1 or 3.2mg/kg).
THC did not induce place conditioning, and a history of THC was ineffective in increasing THC's ability to do so, despite the fact that this same history significantly attenuated the aversive effects of THC.
The failure of THC to consistently induce place preferences has been argued to be a function of its concurrently occurring aversive effects masking its rewarding properties. The fact that pre-exposure to THC significantly reduced its aversive effects without impacting THC's ability to induce place preferences suggests that THC has weak rewarding effects and/or its residual aversive affects may have still masked its rewarding properties. An important area for future work will be characterizing under what conditions THC is rewarding and whether its overall reinforcing effects are impacted by the relationship between its affective properties.
•THC failed to condition a place preference.•Place conditioning with THC was unaffected by THC pre-exposure.•THC induced dose-dependent taste avoidance that was attenuated by THC pre-exposure.•THC appears minimally rewarding, even when its aversive effects are reduced.
Abstract only
Rationale
Δ
9
‐Tetrahydrocannabinol (THC) produces both aversive and rewarding effects in animal models. Given that the balance between a drug's affective properties is thought to ...underlie its abuse potential, it is important to consider these properties of THC and how they (and their balance) are impacted by various factors. In this context, previous studies have examined the effect of THC history on the aversive and rewarding effects of THC. However, such assessments have been made in different animals under different experimental procedures, making it difficult to assess the relative contribution of either affective property to abuse vulnerability.
Methods
In the present experiment, male Sprague‐Dawley rats were administered six pre‐exposure injections (3.2 mg/kg THC) over 12 days. This was followed by a combined taste avoidance/place preference procedure in which a novel saccharin solution and environment were paired with THC (0, 1 or 3.2 mg/kg). Changes in preferences and aversions for the drug‐paired stimuli were evaluated in final place and taste conditioning tests.
Results
Relative to control subjects, THC produced robust taste avoidance, but did not induce place conditioning. Pre‐exposure to THC attenuated THC‐induced taste avoidance and had no effect on place conditioning with THC.
Conclusions
Similar to prior work, THC induced robust and dose‐dependent taste avoidance. The failure to see THC‐induced place preferences is likely due to the aversive effects of THC masking its rewarding properties. Although THC pre‐exposure weakened the aversive effects of THC (as evidenced in the attenuated taste avoidance), some avoidance was still evident (THC‐injected animals drank less than controls). This suggests that the failure to see a change in THC‐induced place preferences following THC pre‐exposure was a function of its residual aversive effects limiting its relatively weak rewarding properties. These findings support the view that the interaction of reward and aversion is important in behavioral displays of the affective properties of abused drugs.
Support or Funding Information
This research was supported by a grant from the Mellon Foundation to Anthony Riley
Geographical distribution of brominated diphenyl ether (BDE) flame retardants in the North American Great Lakes ecosystem in 2000 was determined by analysis of herring gull eggs (13 egg pools) from a ...network of 15 monitoring colonies scattered throughout the lakes and connecting channels. ΣBDEs were found at concentrations ranging from 192 to 1400 μg/kg, mean of 662 ± 368 μg/kg (wet weight of egg contents). Highest concentrations were found in northern Lake Michigan and Toronto harbor (1000−1400 μg/kg) and lowest in Lake Huron and Lake Erie (192−340 μg/kg). The distribution suggested that input from large urban/industrial areas through air or water emissions contributes local contamination to the herring gull food web in addition to background levels from regional/global transport. The congener composition was similar among sampling sites. Major congeners were BDE−47 (43%), BDE−99 (26%), BDE−100 (13%) BDE−153 (11%), BDE−154 (4%), BDE−183 (2%) and BDE−28 (1%). Temporal trends of BDE contamination, 1981−2000, were established by analysis of archived herring gull eggs (10 egg pools) from colonies in northern Lake Michigan, Saginaw Bay, Lake Huron and eastern Lake Ontario. BDE−47, −99 and −100, and BDE-153, −154 and −183 concentrations were grouped separately for analysis because these two groups had different trends and are primarily associated with the Penta BDE and Octa BDE flame retardant formulations, respectively. ΣBDE47,99,100 concentrations were 5−12 μg/kg (wet weight) in 1981−1983 and then increased exponentially (p < 0.00001) at all three sites to 400−1100 μg/kg over the next 17 years. Doubling times were 2.6 years in Lake Michigan, 3.1 years in Lake Huron and 2.8 years in Lake Ontario. ΣBDE154,153,183 concentrations generally increased but varied in an erratic fashion among sites and decreased as a fraction of ΣBDE over time. Concentrations of ΣBDE154,153,183 were 100−200 μg/kg in eggs from all three colonies in 2000. Therefore, most of the dramatic increases in ΣBDE concentrations observed over the past 20 years in the Great Lakes aquatic ecosystem seem to be connected with the Penta BDE formulation, which is mainly used as a flame retardant in polyurethane foam in North America. If present rates of change continue, concentrations of ΣBDEs will equal or surpass those of ΣPCBs in Great Lakes herring gull eggs in 10−15 years.
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