The state of legislation and policy protecting Australia's mangrove and salt marsh and their ecosystem services

Saline coastal wetlands, such as mangrove and coastal salt marsh, provide many ecosystem services. In Australia, large areas have been lost since European colonization, particularly as a result of drainage, infilling and flood-mitigation works, often starting in the mid-19th century and aimed primarily towards converting land to agricultural, urban or industrial uses. These threats remain ongoing, and will be exacerbated by rapid population growth and climate change in the 21st century. Establishing the effect of wetland loss on the delivery of ecosystem services is confounded by the absence of a nationally consistent approach to mapping wetlands and defining the boundaries of different types of coastal wetland. In addition, climate change and its projected effect on mangrove and salt marsh distribution and ecosystem services is poorly, if at all, acknowledged in existing legislation and policy. Intensifying climate change means that there is little time to be complacent; indeed, there is an urgent need for proper valuation of ecosystem services and explicit recognition of ecosystem services within policy and legislation. Seven actions are identified that could improve protection of coastal wetlands and the ecosystem services they provide, including benchmarking and improving coastal wetland extent and health, reducing complexity and inconsistency in governance arrangements, and facilitating wetland adaptation and ecosystem service delivery using a range of relevant mechanisms. Actions that build upon the momentum to mitigate climate change by sequestering carbon – ‘blue carbon’ – could achieve multiple desirable objectives, including climate-change mitigation and adaptation, floodplain rehabilitation and habitat protection.

Loss of 'blue carbon' from coastal salt marshes following habitat disturbance

Increased recognition of the global importance of salt marshes as 'blue carbon' (C) sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2) if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh (Spartinaalterniflora) sediment C levels following seagrass (Thallasiatestudinum) wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA), we recorded 296 patches (7.5 ± 2.3 m(2) mean area ± SE) of vegetation loss (aged 3-12 months) in a salt marsh meadow the size of a soccer field (7 275 m(2)). Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth) were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh) biomass, which otherwise forms the main component of the long-term 'refractory' C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation.

Seventy years of continuous encroachment substantially increases 'blue carbon' capacity as mangroves replace intertidal salt marshes

Shifts in ecosystem structure have been observed over recent decades as woody plants encroach upon grasslands and wetlands globally. The migration of mangrove forests into salt marsh ecosystems is one such shift which could have important implications for global 'blue carbon' stocks. To date, attempts to quantify changes in ecosystem function are essentially constrained to climate-mediated pulses (30 years or less) of encroachment occurring at the thermal limits of mangroves. In this study, we track the continuous, lateral encroachment of mangroves into two south-eastern Australian salt marshes over a period of 70 years and quantify corresponding changes in biomass and belowground C stores. Substantial increases in biomass and belowground C stores have resulted as mangroves replaced salt marsh at both marine and estuarine sites. After 30 years, aboveground biomass was significantly higher than salt marsh, with biomass continuing to increase with mangrove age. Biomass increased at the mesohaline river site by 130 ± 18 Mg biomass km-2 yr-1 (mean ± SE), a 2.5 times higher rate than the marine embayment site (52 ± 10 Mg biomass km-2 yr-1), suggesting local constraints on biomass production. At both sites, and across all vegetation categories, belowground C considerably outweighed aboveground biomass stocks, with belowground C stocks increasing at up to 230 ± 62 Mg C km-2 yr-1 (± SE) as mangrove forests developed. Over the past 70 years, we estimate mangrove encroachment may have already enhanced intertidal biomass by up to 283 097 Mg and belowground C stocks by over 500 000 Mg in the state of New South Wales alone. Under changing climatic conditions and rising sea levels, global blue carbon storage may be enhanced as mangrove encroachment becomes more widespread, thereby countering global warming.

Does agricultural food provide a good alternative to a natural diet for body store deposition in geese?

Over the past decades most goose populations have become increasingly dependent on agricultural crops during wintering and migration periods. The suitability of agricultural crops to support all nutritional requirements of migratory geese for the deposition of body stores has been questioned; feeding on agricultural crops may yield higher rates of fat deposition at the cost of reduced protein accretion due to an unbalanced diet. We compared amino-acid composition of forage, and investigated food-habitat use and dynamics and composition of body stores deposited by barnacle geese feeding on agricultural pasture and in natural salt marsh during spring migratory preparation. Overall content and composition of amino acids was similar among forage from both habitats and appeared equally suitable for protein accretion. There was no relationship between body composition of geese and their preferred food habitat. Fat and wet protein contributed with 67% and 33%, respectively, to body stores gained at a rate of 11 g/d throughout the one-month study period. We found no evidence of impaired protein accretion in geese using agricultural grassland compared to natural salt marsh. Our study supports the hypothesis that the expansion of feeding habitat by including agricultural grassland has played an important role in the recent growth of the East Atlantic flyway population of barnacle geese and other herbivorous waterbirds. Feeding refuges of improved grassland provide geese with an adequate diet for the deposition of body stores crucial for spring migration and subsequent reproduction, thereby alleviating the conflict with agriculture.

Reinventing D'Jillong : current regeneration initiatives challenging the identity and place of Geelong

Australian regional city regeneration in Australia is increasingly becoming an important topic as they attempt to position themselves mid-way between larger discourses about capital cities and peri-urban landscapes. Historically these cities, like Newcastle, Wollongong and Geelong, have been marginalised in infrastructure and planning support systems, yet subject to erratic Commonwealth and State funded initiatives that have divested major specific-purpose complexes into their cities. Such has been as a consequence of of 'decentralisation' and 'regionalisation' political platforms, but also to address employment and voting needs. As an example, Geelong embraced contemporary industrialism, particularly automotive, and built on its port and wool export capacities. Politics, intransigence and lack of economic investment compounded the failure to create quality urban fabric and enable innovative planning. With this legacy, this regional city finds itself at the cusp of heavy industry disintegration, education and health sectorial growth, population increases aided by regional escapism, and a lethargic city centre. In attempting to redress these trends, Geelong is consciously attempting to re-image itself, regenerate key sections of its urban fabric, but also manage the regional escapism (sea change / tree change) phenomena. This paper critiques the larger context, and then uses three examples - "Vision 2" in the city centre, the Mega Port proposal, Fyansford Green and the Moolap salt marsh - as foils to reflect whether these initiatives are and can assist the facilitation of city structural change, economic renewal and enhanced urban design and place-making outcomes.

Ecology of epifaunal caridean shrimps in the Hopkins River estuary, and the role of estuaries in the life history of the atyid "Paratya Australiensis" Kemp, 1917 in south-eastern Australia

This study examined the factors affecting the distribution and abundance of epifaunal caridean shrimps in seagrass meadows of the Hopkins River estuary in south-western Victoria, Australia, and investigated the life history patterns of the freshwater Parana australiensis, found for the first time in estuaries. Adult and sub-adult shrimps were surveyed in seagrass meadows along the estuary over two years, and their planktonic larvae were surveyed in adjacent waters. Three species were collected. The marine Palaemon serenus occurred only near the mouth, summer to autumn, in high salinities. The marine/estuarine Macrobrachium intermedium occurred throughout the estuary. Adults were most abundant in late autumn, and least abundant in summer (unlike trends reported in marine meadows). Densities were higher and less variable in downstream meadows. P. australiensis occurred in the upper estuary all year, most abundantly in spring, due to migration from the river after peak discharge. Ovigerous females dominated, while males, showing less migration into the estuary, dominated above estuarine influence. Adults disappeared from the estuary in summer as salinity rose. Breeding period for P. australiensis was briefer in the estuary (September-December) than upstream (July-April). M. intermedium began breeding later in the upper estuary (November/December-March) than in the lower estuary (October-March), probably reflecting a physiological response to lower salinity, rather than an interaction with P. australiensis. No ovigerous P. serenus were found in the estuary. Larvae of P. australiensis and M intermedium occurred abundantly throughout the estuary, but P. serenus larvae did not. P. australiensis was an early coloniser to the plankton after peak discharge (November-December). Larvae concentrated in the deep saline layer at the head of the intruding salt wedge, thus probably maintaining longitudinal position. Diurnal vertical migrations were evident within the salt wedge, and in a deep pool above tidal influence. M. intermedium larvae occurred October-May in the lower estuary and November-April in the upper estuary, peaking in abundance one to two months after P. australiensis. They were associated with low surface flows and surface salinities greater than 10, over an anoxic deeper layer. All three species exhibited extended development of euryhaline larvae in the laboratory. Tolerances and optimal salinities of larvae of the three species reflected their distributions. M. intermedium was the most euryhaline species. P. australiensis larvae were tolerant of higher salinities than juveniles of adults: capable of developing in salinity of at least 15. Most P. australiensis juveniles recruited to the estuary November-December, after which numbers declined dramatically. After settlement, most recruits probably migrated upstream out of the estuary. Two cohorts of M. intermedium recruited to the estuary from larvae in summer (December and February), but some juveniles also migrated from adjacent coastal waters. Post-larval migration was at least as important a determinant of abundance as direct recruitment from estuarine, planktonic larvae in all three species. Distributions among seagrass meadows along the estuary were determined primarily by physico-chemical patterns driven by hydrological changes. Seasonal variations in salinity and temperature were strongly associated with seasonal variations in shrimp abundance. Salinity tolerances of adults of the three species reflected their distribution patterns. Biotic interactions were more important in determining distributions within meadows. P. australiensis, when abundant, were associated with seagrass biomass. M. intermedium were also, but when seagrass was sparsest and least extensive. The two species apparently partitioned the seagrass meadow according to depth in early summer. Laboratory experiments suggested P. australiensis was displaced from deeper water by M. intermedium. Preference for vegetative complexity and competition for position within meadows suggest the underlying importance of predation in regulating shrimp populations. A survey of south-eastern Australian estuaries found P. australiensis larvae abundant in all stable, open, well-developed, salt-wedge estuaries where adults were abundant. Adults were most abundant in low salinities among submerged leafy macrophytes. Reproductive traits of P. australiensis were compared in estuarine and fresh reaches of three rivers. Early in the breeding season, egg size was smaller, and (size-specific) egg number larger in estuaries than upstream. A trade-off between egg size and egg number resulted in no difference in total (size-specific) reproductive investment between locations. Reproductive investment tended to decrease at some locations over the breeding season, and this decrease was a result of decreased egg size in most cases. The decrease in reproductive investment probably reflected reduced food availability for the adult, while the reduced egg size was probably a response to improved conditions for larval development. In the Hopkins River, larger egg size at upstream sites was reflected in larger early stage larvae. Later stage larvae were larger in the estuary, suggesting more favourable conditions for larval development. Allozyme electrophoresis showed the P. australiensis populations in each of the three rivers to be distinct. Allozyme frequencies were not different within the Hopkins River, but upstream and estuarine locations in the Curdies and Gellibrand were different. Although some variation in reproductive traits within catchments may have been due to genotypic differences, trade-offs between egg size and number, and decreases in egg size over summer were probably due to plastic responses to environmental cues. It is proposed P. australiensis inhabits and reproduces in both estuarine and freshwater environments by plastic response to environmental conditions. Recruitment to estuaries is dependent on the presence of suitable adult, littoral habitat, and a stable salt wedge for larval retention. Estuaries are important recruitment sites for P. australiensis, potentially allowing an extra brood each year before riverine recruitment. Estuarine broods could constitute a large part of the total fecundity of P. australiensis females. Euryhaline larvae and estuarine recruitment of P. australiensis suggest marine transport of larvae between estuaries as a possible dispersal mechanism for Paratya species.

Breeding ecology and bias in offspring sex ratio in little grassbirds (Megalurus gramineus)

Little grassbirds (Megalurus gramineus) are small, sexually monomorphic passerines that live in reed beds, lignum swamps and salt marshes in southern Australia. The breeding biology and patterns of sex allocation of the little grassbird were investigated over a single breeding season. Our observations of this species in the Edithvale Wetland Reserve revealed a highly male-biased population sex ratio, with some breeding territories containing several additional males. Nevertheless, there was little compelling evidence that little grassbirds breed cooperatively. The growth rates of male and female nestlings were similar and, as predicted by theory, there was no overall primary sex ratio bias. However, the primary sex ratio was female-biased early in the breeding season and became increasingly male-biased later in the breeding season.

Report on the biology and ecology of Limonium hyblaeum Brullo at Port Fairy, Victoria, with respect to its invasive potential

Limonium hyblaeum Brullo, a perennial, salt tolerant plant native to Sicily forms a large invasion at Griffiths Island and along the strand of nearby Ocean Road, in Port Fairy, Victoria. This is causing concern as it has every appearance of having a high invasive potential but there is little known of its biology and ecology. This study therefore aimed to investigate aspects of its biology and ecology at Griffiths Island and nearby Ocean Road to identify any characteristics that would indicate its invasive nature, quantitatively determine its impact and determine how invasive it was. It was identified as having some key 'weed' attributes, i.e. being apomictic, allelopathic, fast growing in terms of both cover (40% increase in cover between spring and summer or 0.6 m along a transect line) and dry weight, being able to grow in saline and non-saline conditions and of being a transformer. A weed risk assessment demonstrated it was highly invasive and swift management of the species is recommended.

Key questions in marine megafauna movement ecology

It is a golden age for animal movement studies and so an opportune time to assess priorities for future work. We assembled 40 experts to identify key questions in this field, focussing on marine megafauna, which include a broad range of birds, mammals, reptiles, and fish. Research on these taxa has both underpinned many of the recent technical developments and led to fundamental discoveries in the field. We show that the questions have broad applicability to other taxa, including terrestrial animals, flying insects, and swimming invertebrates, and, as such, this exercise provides a useful roadmap for targeted deployments and data syntheses that should advance the field of movement ecology.