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Fish use of saltmarsh varies spatially, temporally, and with environmental conditions. The specific impact of these effects on fish assemblages in southern temperate Tasmania, Australia—the only mangrove-free Australian state—is as yet largely unknown. Seasonal variation in fish abundance, richness, diversity, and size was investigated in succulent saltmarshes in three estuaries (Marion Bay, Barilla Bay, and Ralphs Bay) in south-eastern Tasmania. All parameters varied between sampling locations. Greater numbers of fish were recorded at two sites (Marion Bay, mean density and standard error of 396.9 ± 71.3 individuals per 100 m2; Barilla Bay, mean density and standard error of 94.1 ± 30.1 individuals per 100 m2) than have been previously reported in Australian saltmarshes. Fish abundance was greatest in July–August (mean density and standard error of 200.2 ± 49.7 individuals per 100 m2) reflecting the breeding patterns of the numerically dominant Atherinosoma microstoma. Both abundance and species richness responded positively to water temperature in ordinal logistic regression models, and species richness and diversity increased with water depth in the models. It is likely that the strong differences between sampling locations are partly related to differences in water depth and water temperature between the estuaries. They may be also related to the habitat context of each estuary, especially the presence or absence of seagrass. The greater numbers of fish found in the present study relative to abundances reported in mainland Australia may relate to the absence of mangroves and the consequent differences in seascape habitat context, including greater water depths in marshes. Importantly, these results demonstrate that temperate southern hemisphere saltmarshes are year-round habitat for fish, thus emphasising their importance as a fish habitat. [ABSTRACT FROM AUTHOR]

Vegetation changes in saltmarsh habitat can influence fish assemblages and abundance. In Tasmania, Australia, mid‐latitude succulent saltmarsh communities have been invaded by the introduced tall grass, Spartina anglica. Eradication efforts have been ongoing since the 1990s with purported benefits for fish access to intertidal foraging grounds, but a lack of knowledge of the impact of S. anglica on fish limits understanding of the benefits and effectiveness of native habitat restoration. Here, we investigate whether fish assemblages in native saltmarshes and non‐native S. anglica grassland differ in species diversity, fish abundance, and size class distribution. We used buoyant pop nets to sample fishes in Sarcocornia quinqueflora herbland and S. anglica grassland swards at three sampling stations in northwest Tasmania. Very few individuals and low species diversity were recorded in both vegetation types at the sampling station with the most well‐established S. anglica infestation. Elsewhere, richness and diversity were higher in S. quinqueflora herbland. Overall fish abundance was higher in S. quinqueflora than in S. anglica, with a very strong effect at one sampling station. Fewer small individuals of the numerically dominant Atherinosoma microstoma were recorded in S. anglica, potentially indicating impaired nursery function. Our results provide important insights for S. anglica control, as we are the first to demonstrate a relationship between S. anglica presence and fish characteristics in southern Australian saltmarsh. These results indicate that S. anglica control is valuable for fish conservation. An extension of our research to document the effects of S. anglica removal on fishes is desirable. [ABSTRACT FROM AUTHOR]

Temperate Australian saltmarshes, including those in the southern island state of Tasmania, are considered to be a threatened ecological community under Australian federal legislation. There is a need to improve our understanding of the ecological components, functional relationships and threatening processes of Tasmanian coastal saltmarshes and distil research priorities that could assist recovery actions. A semisystematic review of the literature on Tasmanian coastal saltmarshes supported by expert local knowledge identified 75 studies from 1947 to 2019. Existing understanding pertains to saltmarsh plants, soils, invertebrates and human impacts with ongoing studies currently adding to this knowledge base. Several knowledge gaps remain, and the present review recommends six key priority areas for research: (1) citizen science–organised inventory of (initially) saltmarsh birds, plants and human impacts with the potential for expansion of datasets; (2) use of saltmarsh by marine transient species including fish and decapods; (3) use of saltmarsh by, and interactions with, native and introduced mammals; (4) invertebrates and their interactions with predators (e.g. birds, fish) and prey (e.g. insects, plants, detritus); (5) historic saltmarsh loss and priority areas for conservation; (6) monitoring changes to saltmarsh due to both localised human impacts (e.g. grazing, eutrophication, destruction) and global change factors (e.g. climate change, sea-level rise). Addressing these research priorities will help in developing a better understanding of the ecological character of Tasmanian coastal saltmarshes and improve their conservation management. A semisystematic literature review supported by expert local knowledge documents existing knowledge on the ecological components, functional relationships and threatening processes of Tasmanian coastal saltmarshes. Research gaps and priorities are identified to assist saltmarsh recovery actions and improve its conservation status. [ABSTRACT FROM AUTHOR]

Effective conservation of saltmarshes involves detailed and accurate mapping of their range, area of occupancy and plant community composition as part of region‐wide inventories. There is also a need to identify the major mesoscale influences on the distributions of types of saltmarsh, obligate saltmarsh plants and salt pans, and evaluate possible responses to macroclimatic changes.Tidal saltmarshes of Tasmania and its offshore islands (coastline of 4,882 km, spanning latitudes 39°40′ to 43°40′S), off south‐eastern Australia, were mapped at a high spatial resolution of 1 : 500–1 : 3,000. The distributions of types of saltmarsh, obligate plant taxa and salt pans were related to climatic, geomorphic and land‐use variation. The future distribution of climatically controlled species and communities was determined for two climate change scenarios.There was 58.6 km2 of tidal saltmarsh in Tasmania in 61 mesoscale complexes. The complexes were classified into three broad saltmarsh groups, which together offer a more ecologically relevant planning unit for saltmarsh conservation than macroscale bioregions. The small median patch size of 0.2 ha demonstrates the effectiveness of the manual interpretation and mapping with extensive field checking. Mapping of these smaller saltmarshes provides them recognition within the land use planning and approvals process.Climatic, but not geomorphic and land‐use, factors have strong effects on the distribution of saltmarsh plant communities, species and salt pans in Tasmania. Mean annual rainfall was most significant in predicting saltmarsh extent, range, plant community composition, salt pans and the three saltmarsh groups. Mean annual daily minimum temperature and saltmarsh area best predicted obligate plant distributions.Projected wetter and drier climatic change by 2100 is not expected to substantially alter macroscale plant community patterns but may reduce the range of the rare herb Wilsonia humilis R.Br. However, stochastic disturbances may continue to play an important role at local scales. [ABSTRACT FROM AUTHOR]

Rising sea levels and changing wind climates are widely expected to be associated with receding coastlines, creating a planning need for coastal change prediction, especially for soft shores like those associated with saltmarsh. We ask whether it is possible use a simple cartographic wind-wave fetch method to estimate the spatial pattern of progradation and recession of soft shores in swell-sheltered situations in which there is little or no input of new sediment from terrestrial sources. For points on an extensive embayment shoreline of this type we mapped change over 54 years from aerial photographs, recorded current shoreline morphology and calculated a wave fetch index (WFI). Morphological indication of strong progradation was associated with low WFI, but there was no statistically significant effect of variation in WFI on the degree of shoreline retreat. Saltmarsh shorelines averaged 14 cm per annum retreat between 1952 and 2006, a rate that did not vary significantly between air photo periods. We conclude that our geographic information system approach utilising WFI is likely to be useful as a planning tool in identifying those parts of sediment-poor saltmarsh shores where erosion is most likely or least likely to occur, but not particularly useful for predicting finer-scale variation in rates of shoreline recession within the particular substrate types in our study area. In the context of relative sea-level rise and increasing wind speeds, such modelling can help identify coastlines which are likely to support saltmarshes into the future. [ABSTRACT FROM AUTHOR]

Coastal saltmarshes of temperate Australia are in decline and have recently been listed as a threatened ecological community under Federal legislation. Further research is required to better understand both the extent and nature of their decline in order to plan their recovery. A case study is presented of the most extensive area of saltmarshes in Tasmania, on the north-west Circular Flead coast. A mixture of aerial photographs and ground-truthing data were used to determine human impacts and saltmarsh loss between 1952 and 2006. There was an absolute loss of 219 ha since 1952, largely due to the effects of a 24.5 km network of levees. Of the 1 153 ha of saltmarshes that remained in 2006, a further 752 ha (65%) was associated with one or several of land-based human impacts. This left 401 ha (35%) of saltmarshes that had no recorded human impacts and a contiguous vegetative buffer zone of 50-100 m. These areas represent some of the least disturbed saltmarshes in Tasmania and warrant adequate conservation measures. Future planning for conservation and the use of land and marine resources should strive to promote both the extent and functional health of saltmarshes. [ABSTRACT FROM AUTHOR]