Variability in haul-out behaviour by male Australian sea lions Neophoca cinerea in the Perth metropolitan area, Western Australia

© The authors 2015. Pinnipeds spend significant time hauled out, and their haul-out behaviour can be dependent on environment and life stage. In Western Australia, male Australian sea lions Neo - phoca cinerea haul out on Perth metropolitan islands, with numbers peaking during aseasonal (~17.4 mo in duration), non-breeding periods. Little is known about daily haul-out patterns and their association with environmental conditions. Such detail is necessary to accurately monitor behavioural patterns and local abundance, ultimately improving long-term conservation management, particularly where, due to lack of availability, typical pup counts are infeasible. Hourly counts of N. cinerea were conducted from 08:00 to 16:00 h on Seal and Carnac Islands for 166 d over 2 yr, including 2 peak periods. Generalised additive models were used to determine effects of temporal and environmental factors on N. cinerea haul-out numbers. On Seal Island, numbers increased significantly throughout the day during both peak periods, but only did so in the second peak on Carnac. During non-peak periods there were no significant daytime changes. Despite high day-to-day variation, a greater and more stable number of N. cinerea hauled out on the significantly smaller beach of Seal Island during 1 peak. Overall, numbers hauled out were associated with temperature and tidal height, but not wind speed. Relative percentages of age classes hauled out also varied with time of breeding cycle. Due to high variability in haul-out behaviour in space and time, and its association with environmental conditions, we conclude that counts for monitoring relative abundance in management decisions should be conducted systematically, using robust survey designs with relatively large sample sizes

Atypical residency of short-beaked common dolphins (Delphinus delphis) to a shallow, urbanised embayment in south-eastern Australia

Short-beaked common dolphins (Delphinus delphis) are typically considered highly mobile, offshore delphinids. This study assessed the residency of a small community of short-beaked common dolphins in the shallow, urbanized Port Phillip Bay, south-eastern Australia. The ability to identify common dolphins by their dorsal fin markings and coloration using photo-identification was also investigated. Systematic and non-systematic boat surveys were undertaken between 2007 and 2014. Results showed that 13 adult common dolphins and their offspring inhabit Port Phillip Bay, of which 10 adults exhibit residency to the bay. The majority of these adults are reproductively active females, suggesting that female philopatry may occur in the community. Systematic surveys conducted between 2012 and 2014 revealed that the dolphins were found in a median water depth of 16 m and median distance of 2.2 km from the coast. The shallow, urbanized habitat of this resident common dolphin community is atypical for this species. As a result, these common dolphins face threats usually associated with inshore bottlenose dolphin communities. We suggest that the Port Phillip Bay common dolphin community is considered and managed separate to those outside the embayment and offshore to ensure the community's long-term viability and residency in the bay

Matching signature whistles with photo-identification of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Fremantle Inner Harbour, Western Australia

The Swan–Canning River System is home to an Indo-Pacific bottlenose dolphin (Tursiops aduncus) community of currently 17 adult and juvenile individuals. While a complete photo-identification catalogue exists, visual monitoring requires repeated boat-based surveys and is thus laborious and expensive. Bottlenose dolphins are known to emit individually distinctive signature whistles, and therefore, passive acoustic monitoring could be a reliable and more efficient tool. Archived acoustic and photographic data from the Fremantle Inner Harbour were reviewed for instances when dolphin whistles and individual identifying images were simultaneously available. As dolphin whistles are commonly used in social encounters, dolphins producing whistles in this study were always in groups. Consequently, to assess whether distinctive whistles could be attributed to individual dolphins, conditional probabilities for recording a specific whistle in the presence of certain individuals, as well as Bayesian posterior probabilities for encountering a specific individual at times of certain whistles were computed. While a larger sample size is needed to capture all individuals in diverse groupings, this study provides the first step in developing a passive acoustic program for monitoring this small dolphin community, in order to ultimately inform its conservation management. © 2020, Australian Acoustical Society

Seasonal productivity drives aggregations of killer whales and other cetaceans over submarine canyons of the Bremer Sub-Basin, south-western Australia

Cetaceans are iconic predators that serve as important indicators of marine ecosystem health. The Bremer Sub-Basin, south-western Australia, supports a diverse cetacean community including the largest documented aggregation of killer whales (Orcinus orca) in Australian waters. Knowledge of cetacean distributions is critical for managing the area’s thriving ecotourism industry, yet is largely sporadic. Here we combined aerial with opportunistic ship-borne surveys during 2015–2017 to describe the occurrence of multiple cetacean species on a regional scale. We used generalised estimating equations to model variation in killer whale relative density as a function of both static and dynamic covariates, including seabed depth, slope, and chlorophyll a concentration, while accounting for autocorrelation. Encountered cetacean groups included: killer (n ¼ 177), sperm (n ¼ 69), long-finned pilot (n ¼ 29), false killer (n ¼ 2), and straptoothed beaked (n ¼ 1) whales, as well as bottlenose (n ¼ 12) and common (n ¼ 5) dolphins. Killer whale numbers peaked in areas of low temperatures and high primary productivity, likely due to seasonal upwelling of nutrient-rich waters supporting high prey biomass. The best predictive model highlighted potential killer whale ‘hotspots’ in the Henry, Hood, Pallinup and Bremer Canyons. This study demonstrates the value of abundance data from platforms of opportunity for marine planning and wildlife management in the open ocean

The use of singlebeam echo-sounder depth data to produce demersal fish distribution models that are comparable to models produced using multibeam echo-sounder depth

Seafloor characteristics can help in the prediction of fish distribution, which is required for fisheries and conservation management. Despite this, only 5%–10% of the world's seafloor has been mapped at high resolution, as it is a time-consuming and expensive process. Multibeam echo-sounders (MBES) can produce high-resolution bathymetry and a broad swath coverage of the seafloor, but require greater financial and technical resources for operation and data analysis than singlebeam echo-sounders (SBES). In contrast, SBES provide comparatively limited spatial coverage, as only a single measurement is made from directly under the vessel. Thus, producing a continuous map requires interpolation to fill gaps between transects. This study assesses the performance of demersal fish species distribution models by comparing those derived from interpolated SBES data with full-coverage MBES distribution models. A Random Forest classifier was used to model the distribution of Abalistes stellatus, Gymnocranius grandoculis, Lagocephalus sceleratus, Loxodon macrorhinus, Pristipomoides multidens, and Pristipomoides typus, with depth and depth derivatives (slope, aspect, standard deviation of depth, terrain ruggedness index, mean curvature, and topographic position index) as explanatory variables. The results indicated that distribution models for A. stellatus, G. grandoculis, L. sceleratus, and L. macrorhinus performed poorly for MBES and SBES data with area under the receiver operator curves (AUC) below 0.7. Consequently, the distribution of these species could not be predicted by seafloor characteristics produced from either echo-sounder type. Distribution models for P. multidens and P. typus performed well for MBES and the SBES data with an AUC above 0.8. Depth was the most important variable explaining the distribution of P. multidens and P. typus in both MBES and SBES models. While further research is needed, this study shows that in resource-limited scenarios, SBES can produce comparable results to MBES for use in demersal fish management and conservation

Cetacean sightings within the Great Pacific Garbage Patch

Here, we report cetacean sightings made within a major oceanic accumulation zone for plastics, often referred to as the ‘Great Pacific Garbage Patch’ (GPGP). These cetacean records occurred in October 2016 and were made by sensors and trained observers aboard a Hercules C-130 aircraft surveying the GPGP at 400 m height and 140 knots speed. Four sperm whales (including a mother and calf pair), three beaked whales, two baleen whales, and at least five other cetaceans were observed. Many surface drifting plastics were also detected, including fishing nets, ropes, floats and fragmented debris. Some of these objects were close to the sighted mammals, posing entanglement and ingestion risks to animals using the GPGP as a migration corridor or core habitat. Our study demonstrates the potential exposure of several cetacean species to the high levels of plastic pollution in the area. Further research is required to evaluate the potential effects of the GPGP on marine mammal populations inhabiting the North Pacific

The influence of abiotic and biotic conditions on lifecycle stages is critical for estuarine seagrass resilience

Abiotic and biotic factors influence seagrass resilience, but the strength and relative importance of the effects are rarely assessed over the complete lifecycle. This study examined the effects of abiotic (salinity, temperature, water depth) and biotic (grazing by black swans) factors on Ruppia spp. over the complete lifecycle. Structures were set up in two estuaries ( – 33.637020, 115.412608) that prevented and allowed natural swan grazing of the seagrasses in May 2019, before the start of the growing season. The density of life stage(s) was measured from June 2019 when germination commenced through to January 2020 when most of the seagrass senesced. Our results showed that swans impacted some but not all life stages. Seedling densities were significantly higher in the plots that allowed natural grazing compared to the exclusion plots (e.g. 697 versus 311 seedlings per m-2), revealing an apparent benefit of swans. Swans removed ≤ 10% of seagrass vegetation but a dormant seedbank was present and new propagules were also observed. We conclude that grazing by swans provides some benefit to seagrass resilience by enhancing seedling recruitment. We further investigated the drivers of the different lifecycle stages using general additive mixed models. Higher and more variable salinity led to increased seed germination whilst temperature explained variation in seedling density and adult plant abundance. Bet-hedging strategies of R. polycarpa were revealed by our lifecycle assessment including the presence of a dormant seedbank, germinated seeds and seedlings over the 8-month study period over variable conditions (salinity 2–42 ppt; temperatures 11–28 °C). These strategies may be key determinants of resilience to emerging salinity and temperature regimes from a changing climate

The development of the Western Australian Haemodialysis Vascular Access Complexity Instrument

Background The Western Australian Haemodialysis Vascular Access Classification instrument was developed to classify the cannulation complexity of the arteriovenous fistula or arteriovenous graft as simple, challenging, or complex. Although the instrument was developed by experts in haemodialysis nursing, the instrument had not undergone formal validity or reliability testing. Objectives Evaluate the Western Australian Haemodialysis Vascular Access Classification instrument for content validity, interrater and test–retest reliability. Design Prospective cohort study. Participants Content validity was assessed by haemodialysis nursing experts (n = 8). The reliability testing occurred in one in-centre and one satellite haemodialysis unit in Western Australia from September to November 2019. Reliability testing was performed by 38 haemodialysis nurses in 67 patients receiving haemodialysis and 247 episodes of cannulation. Measurements Interrater and test–retest reliability assessment was conducted using κ, adjusted κ, Bland–Altman plots, intraclass correlation coefficient and Pearson\u27s correlation coefficient. Results The final version of the instrument (n = 20 items) had individual item-level content validity indices ranging from 0.625 to 1.00 with a scale-level content validity index of 0.89. For both interrater (n = 172 pairs) and test–retest (n = 101 pairs), most individual variables had excellent adjusted κ (n = 33 variables), some fair to good agreement (n = 6 variables) and one variable with poor agreement. The classification of simple, challenging and complex demonstrated adjusted κ of fair to good, to excellent agreement for interrater reliability with lower levels of agreement for test–retest reliability. Conclusions This instrument may be used to match a competency-assessed nurse to perform the cannulation thereby minimising the risk of missed cannulation and trauma