Hydrodynamics and Flushing of Coffin Bay, South Australia: A Small Tidal Inverse Estuary of Interconnected Bays

Kämpf, Jochen; Ellis, Henry

doi:10.2112/jcoastres-d-14-00046.1

Cited by 18 publications

(25 citation statements)

References 31 publications

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“…One of the main predators of dolphins in coastal waters of South Australia is the white shark ( Carchharodon carcharias ), which can occur close to shore although they seem to prefer waters of <100 m depth (Bruce, Stevens, & Malcolm, ). Additionally, the high diversity of habitats (Miller, Westphalen, Jolley, & Brayford, ) and differences in environmental conditions found in Coffin Bay (Kämpf & Ellis, ) likely result in different fish assemblages across its different embayments. A contemporary study performed in autumn and spring 2015 revealed that, in fact, fish assemblage composition differ among embayments of the inner area (i.e., Kellidie vs. Mount Dutton vs. north of Port Douglas vs. south of Port Douglas) (S. Whitmarsh, personal communication, 14 March 2017).…”

Section: Discussionmentioning

confidence: 99%

“…Due to their high site fidelity and restricted ranging patterns, it is likely that resident individuals inhabiting specific areas may be facing different threats. For instance, Mount Dutton and Kellidie bays are particularly vulnerable to harmful algae blooms and pollution because of their relatively slow flushing (water age of ~3 months; Kämpf & Ellis, ), which can result in cascade effects producing mortalities of prey (e.g., PIRSA, ) and potentially also affecting dolphins. The spatial distributions of threats to southern Australian bottlenose dolphins, however, are poorly understood.…”

Section: Discussionmentioning

confidence: 99%

“…It is divided into an inner (~123 km 2 ) and an outer area (~140 km 2 ) by a narrow and long (5 km) spit of land called Point Longnose, which restricts water exchange through a narrow opening between both areas. The inner area is a small inverse estuary that consists of several interconnected shallow (mean depth ~2.5 m) bays such as Port Douglas, Mount Dutton, and Kellidie (DEH, ; Saunders, ; Kämpf & Ellis, ; Figure ). Evaporation rates exceeding precipitation between September and April lead to hypersaline conditions during austral summer; while in austral winter (June–August), the inverse pattern dilutes salinity leading to fresher waters mainly in Kellidie and Mount Dutton bays (Kämpf & Ellis, ).…”

Section: Methodsmentioning

confidence: 99%

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High site fidelity and restricted ranging patterns in southern Australian bottlenose dolphins

Passadore

Möller

Diaz‐Aguirre

et al. 2017

Ecology and Evolution

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Information on site fidelity and ranging patterns of wild animals is critical to understand how they use their environment and guide conservation and management strategies. Delphinids show a wide variety of site fidelity and ranging patterns. Between September 2013 and October 2015, we used boat‐based surveys, photographic identification, biopsy sampling, clustering analysis, and geographic information systems to determine the site‐fidelity patterns and representative ranges of southern Australian bottlenose dolphins (Tursiops cf. australis) inhabiting the inner area of Coffin Bay, a highly productive inverse estuary located within Thorny Passage Marine Park, South Australia. Agglomerative hierarchical clustering (AHC) of individuals’ site‐fidelity index and sighting rates indicated that the majority of dolphins within the inner area of Coffin Bay are “regular residents” (n = 125), followed by “occasional residents” (n = 28), and “occasional visitors” (n = 26). The low standard distance deviation indicated that resident dolphins remained close to their main center of use (range = 0.7–4.7 km, X ± SD = 2.3 ± 0.9 km). Representative ranges of resident dolphins were small (range = 3.9–33.5 km2, X ± SD = 15.2 ± 6.8 km2), with no significant differences between males and females (Kruskal–Wallis, χ2 = 0.426, p = .808). The representative range of 56% of the resident dolphins was restricted to a particular bay within the study area. The strong site fidelity and restricted ranging patterns among individuals could be linked to the high population density of this species in the inner area of Coffin Bay, coupled with differences in social structure and feeding habits. Our results emphasize the importance of productive habitats as a major factor driving site fidelity and restricted movement patterns in highly mobile marine mammals and the high conservation value of the inner area of Coffin Bay for southern Australian bottlenose dolphins.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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High site fidelity and restricted ranging patterns in southern Australian bottlenose dolphins

Passadore

Möller

Diaz‐Aguirre

et al. 2017

Ecology and Evolution

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“…The high abundance of both females and males in Coffin Bay's inner area across seasons suggests this area offers highly favourable year‐round habitat conditions. Upwelling events off the adjacent continental shelf during summer–autumn months bring cold nutrient‐rich water into nearshore waters of Coffin Bay resulting in highly productive waters (Kämpf, Doubell, Griffin, Matthews, & Ward, ; Kämpf & Ellis, ). This high productivity coupled with the high habitat diversity found within Coffin Bay (Miller et al, ) likely promotes high prey availability year round.…”

Section: Discussionmentioning

confidence: 99%

“…(DENR, ). Furthermore, the shallow waters (mean depth ~ 2.5 m) of the inner bays, and the relatively narrow connection between the inner area and the more exposed waters of the outer area (Kämpf & Ellis, ), could be providing a degree of protection to the dolphins by limiting, to some extent, the access of predators such as white sharks ( Carcharodon carcharias ) to the inner area, resulting in lower predation risk. Future studies on dolphins' diet, and prey and predator abundance within Coffin Bay are needed to test these hypotheses and to better understand the ecological factors sustaining the high density of dolphins in this area.…”

Section: Discussionmentioning

confidence: 99%

Demography of southern Australian bottlenose dolphins living in a protected inverse estuary

Passadore

Möller

Diaz‐Aguirre

et al. 2017

Aquatic Conservation

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Assessments of demographic parameters are essential to understand the dynamics of wild populations, and for their efficient conservation and management. Here, sex‐specific abundance, apparent survival and temporary emigration of southern Australian bottlenose dolphins (Tursiops cf. australis) in Coffin Bay (CB), South Australia, is investigated. Results are based on capture–recapture modelling of photo‐identification data and molecular analyses of biopsy samples collected during boat‐based surveys between September 2013 and October 2015 in the inner and outer areas of CB. The total super‐population of dolphins (including calves) using the entire study area (263 km2) was estimated with POPAN models at 306 (95% CI: 291–323), which included 71 (68–73) marked females and 57 (55–60) marked males. Seasonal estimates of abundance for the inner area of CB (123 km2) obtained with Pollock's Closed Robust Design models remained relatively constant over the two years (marked females: 52–60, marked males: 46–52, and total: 193–209). The high density of dolphins inhabiting the inner area (seasonal range: 1.57–1.70 individuals km−2), high apparent survival rates estimated for both sexes (females: 0.99; 95% CI: 0.96–1.0; males: 0.95; 0.82–0.99), and low temporary emigration rates (0.02; 95% CI: 0.01–0.11) indicate that the inner area of CB offers highly favourable habitat for these dolphins. 6‐High biological productivity and low predation risk may promote these demographic patterns in the inner area of CB. 7‐This study provides a robust baseline of sex‐specific population demographics of southern Australian bottlenose dolphins with important implications for future research and their management and conservation in South Australia.

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Environmental drivers of yellowtail kingfish, Seriola lalandi, activity inferred through a continental acoustic tracking network

Clarke,

Whitmarsh,

Jaine

et al. 2023

Aquatic Conservation

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Identifying the species response to changing environments can contribute towards proactive and adaptable resource management and, although obtaining observations can be logistically challenging for aquatic species, can be postulated through monitoring. A network of acoustic tracking receivers (n = 93) across south‐eastern Australia was used to identify the effects of environmental conditions on the activity of the yellowtail kingfish (Seriola lalandi, n = 63), an economically important species with a crucial role in pelagic ecosystems. Activity (measured via tri‐axial acceleration) provides an insight into the energetic expenditure of animals, which is linked to movement, behaviour, and physiological processes. Kingfish activity was strongly influenced by sea surface temperature and hour of day, with smaller effects from distance to nearest landmass and bathymetry. Activity also decreased during higher tides and periods of greater moon fraction. Findings show that the energetic responses of kingfish are sensitive to long‐ and short‐term changes, which can regulate behaviours and physiological processes. Changes in kingfish activity and movement (residency and space use) were further investigated at a seasonal aggregation in a small temperate estuary (approx. 120 km2; Coffin Bay, South Australia), where individuals remained during the austral spring and summer (September–April), with a complete exodus in winter. Fifty per cent of tagged fish returned to this estuary in three consecutive years, indicating its importance for aggregating kingfish. While residing in Coffin Bay, kingfish activity varied between interconnected areas, with temperature, hour of day, tide height, and moon fraction again identified as important explanatory variables. These findings have implications for the energetic budgets of large pelagic fish in subtropical and temperate regions, which are facing rapidly changing climates. These results are important for understanding and accounting for the potential responses and physiological impacts of future climatic conditions on migratory pelagic species.

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Hydrodynamics and Flushing of Coffin Bay, South Australia: A Small Tidal Inverse Estuary of Interconnected Bays

Cited by 18 publications

References 31 publications

High site fidelity and restricted ranging patterns in southern Australian bottlenose dolphins

High site fidelity and restricted ranging patterns in southern Australian bottlenose dolphins

Demography of southern Australian bottlenose dolphins living in a protected inverse estuary

Environmental drivers of yellowtail kingfish, Seriola lalandi, activity inferred through a continental acoustic tracking network

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