A deep dive into the ecology of Gamay (Botany Bay, Australia): current knowledge and future priorities for this highly modified coastal waterway

Context: Gamay is a coastal waterway of immense social, cultural and ecological value. Since European settlement, it has become a hub for industrialisation and human modification. There is growing desire for ecosystem-level management of urban waterways, but such efforts are often challenged by a lack of integrated knowledge. Aim and methods: We systematically reviewed published literature and traditional ecological knowledge (TEK), and consulted scientists to produce a review of Gamay that synthesises published knowledge of Gamay’s aquatic ecosystem to identify knowledge gaps and future research opportunities. Key results: We found 577 published resources on Gamay, of which over 70% focused on ecology. Intertidal rocky shores were the most studied habitat, focusing on invertebrate communities. Few studies considered multiple habitats or taxa. Studies investigating cumulative human impacts, long-term trends and habitat connectivity are lacking, and the broader ecological role of artificial substrate as habitat in Gamay is poorly understood. TEK of Gamay remains a significant knowledge gap. Habitat restoration has shown promising results and could provide opportunities to improve affected habitats in the future. Conclusion and implications: This review highlights the extensive amount of knowledge that exists for Gamay, but also identifies key gaps that need to be filled for effective management

Patterns of the non-indigenous isopod Cirolana harfordi in Sydney Harbour.

Biological introductions can alter the ecology of local assemblages and are an important driver of global environmental change. The first step towards understanding the impact of a non-indigenous species is to study its distribution and associations in the invaded area. In Sydney Harbour, the non-indigenous isopod Cirolana harfordi has been reported in densities up to 0.5 individuals per cm(2) in mussel-beds. Abundances of this species have, however, been largely overlooked in other key habitats. The first aim of this study was to evaluate the abundances and distribution of C. harfordi across different habitats representative of Sydney Harbour. Results showed that C. harfordi occurred in oyster and mussel-beds, being particularly abundant in oyster-beds. We also aimed to determine the role of C. harfordi as a predator, scavenger and detritus feeder by investigating the relationships between densities of C. harfordi and (i) the structure of the resident assemblages, and (ii) deposited organic matter in oyster-beds. Densities of C. harfordi were not related to the structure of the assemblages, nor amounts of deposited organic matter. These findings suggested little or no ecological impacts of C. harfordi in oyster-beds. These relationships may, however, affect other variables such as growth of individuals, or be disguised by high variability of assemblages among different locations. Future studies should, therefore, test the impacts of C. harfordi on the size of organisms in the assemblage and use manipulative experiments to control for spatial variation. This study is the first published work on the ecology of the invasion of C. harfordi and provides the starting-point for the study of the impacts of this species in Sydney Harbour

DISTLM of the densities of <i>Cirolana harfordi</i> in oyster-beds, using Thickness of the habitat, Concentration of organic matter smaller than 64 µm (OM<64), Concentration of organic matter between 64 and 500 µm (OM 64–500) and Location as predictor variables. For marginal tests, variables are taken individually; for sequential tests, variables were chosen using Forward selection criteria. The column %var indicates the percentage of the variation explained by the predictor variables. Cum % is the cumulative percentage of variance explained.

<p>DISTLM of the densities of <i>Cirolana harfordi</i> in oyster-beds, using Thickness of the habitat, Concentration of organic matter smaller than 64 µm (OM<64), Concentration of organic matter between 64 and 500 µm (OM 64–500) and Location as predictor variables. For marginal tests, variables are taken individually; for sequential tests, variables were chosen using Forward selection criteria. The column %var indicates the percentage of the variation explained by the predictor variables. Cum % is the cumulative percentage of variance explained.</p

Relationships between <i>C. harfordi</i> and organic matter and thickness of the habitat.

<p>Densities of <i>Cirolana harfordi</i> and (A) concentration of organic matter smaller than 64 µm (triangles) and 64–500 µm (circles) and (B) thickness of the oyster-bed at Greenwich (white) and Berrys Bay (black)</p

Densities of <i>Cirolana harfordi</i> (mean ± S.E. number of individuals in 100 ml of oyster-bed) compared with densities of the most abundant arthropods (Chironomidae larvae and <i>Dynoides barnardii</i>) at Greenwich, Berrys Bay and Neutral Bay in June and October 2010. Greenwich was not sampled in June 2010 (see methods).

<p>Densities of <i>Cirolana harfordi</i> (mean ± S.E. number of individuals in 100 ml of oyster-bed) compared with densities of the most abundant arthropods (Chironomidae larvae and <i>Dynoides barnardii</i>) at Greenwich, Berrys Bay and Neutral Bay in June and October 2010. Greenwich was not sampled in June 2010 (see methods).</p

Analyses of the effects of the densities of <i>Cirolana harfordi</i> on densities per taxa, total abundance and number of taxa of the assemblage in oyster-beds in June and October 2010. PERMANOVA (9999 permutations of residuals under reduced model) of Bray-Curtis similarities for the densities per taxa (forth root transformed) and Euclidean distances for total abundance and number of taxa in oyster-beds, where Location is the comparison among three locations in June and six locations in October 2010 (random) and Patch is the comparison among three patches per location (random, nested in Location), using the densities of <i>C. harfordi</i> as a covariate. Factor Patch was not included in the analysis in October 2010 (see methods). ^a Terms eliminated to increase the power for factors higher in the table.

<p>Analyses of the effects of the densities of <i>Cirolana harfordi</i> on densities per taxa, total abundance and number of taxa of the assemblage in oyster-beds in June and October 2010. PERMANOVA (9999 permutations of residuals under reduced model) of Bray-Curtis similarities for the densities per taxa (forth root transformed) and Euclidean distances for total abundance and number of taxa in oyster-beds, where Location is the comparison among three locations in June and six locations in October 2010 (random) and Patch is the comparison among three patches per location (random, nested in Location), using the densities of <i>C. harfordi</i> as a covariate. Factor Patch was not included in the analysis in October 2010 (see methods). ^a Terms eliminated to increase the power for factors higher in the table.</p

Distribution along Sydney Harbour.

<p>Mean densities of <i>Cirolana harfordi</i> (ind/100 ml of sample) in oyster-beds in Sydney Harbour. Berrys Bay, Neutral Bay and Bradley's Head were sampled in June (grey) and October (black) 2010. Henley, Greenwich and Little Manly were sampled only in October 2010 (see methods). There were no <i>C. harfordi</i> individuals found at Henley and Little Manly.</p

Locations sampled.

<p>Locations sampled in Sydney Harbour for oyster-beds (black circles), mussel-beds (squares) and coralline turfs (white circles).</p

Variation in the density and body size of a threatened foundation species across multiple spatial scales

Population characteristics (e.g. density and body sizes) of foundation species can affect their own persistence and provisioning of ecosystem functions. Understanding the drivers of population characteristics of foundation species at multiple spatial scales is therefore critical for maximizing ecosystem functions of restored habitats. We analyzed variation in population characteristics (densities, 95th percentile, and median lengths of live oysters) of the Sydney rock oyster, Saccostrea glomerata, on remnant oyster reefs at regional scales (among three estuaries) along an approximately 250 km of coastline in New South Wales, Australia. We then analyzed how population characteristics were further related to spatial attributes at smaller spatial scales including within-patches (rugosity, distance to patch-edge, and elevation), whole-patches (size and shape), and among-patch (connectivity) within each estuary. The densities and body sizes of S. glomerata were related to spatial attributes occurring within-patch (e.g. elevation), whole-patch (e.g. shape), and landscape (i.e. connectivity) scales, but these relationships varied among estuaries. The greatest variation in oyster density and size occurred at regional scales, suggesting that processes acting at larger spatial scales (e.g. water quality and/or climate) set the context for smaller scale influences on oyster characteristics. Our results highlight the potential importance of incorporating site-specific, spatial attributes in the design of restored oyster reefs to maximize ecosystem services and functions provided by restoration efforts.Published versionResearch was funded by an Australian Research Council Linkage Grant LP180100732, in collaboration with The Nature Conservancy, NSW DPI, NSW Department of Planning, Industry, and Environment, and the Sydney Institute of Marine Science Foundation. R.C.L. was supported by a University of New South Wales University International Postgraduate Award (UIPA) during this research. Open access publishing facilitated by University of New South Wales, as part of the Wiley - University of New South Wales agreement via the Council of Australian University Librarians

Supporting urban ecosystem services across terrestrial, marine and freshwater realms

The terrestrial, freshwater and marine realms all provide essential ecosystem services in urban environments. However, the services provided by each realm are often considered independently, which ignores the synergies between them and risks underestimating the benefits derived collectively. Greater research collaboration across these realms, and an integrated approach to management decisions can help to support urban developments and restoration projects in maintaining or enhancing ecosystem services. The aim of this paper is to highlight the synergies and trade-offs among ecosystem services provided by each realm and to offer suggestions on how to improve current practice. We use case studies to illustrate the flow of services across realms. In our call to better integrate research and management across realms, we present a framework that provides a 6-step process for conducting collaborative research and management with an Australian perspective. Our framework considers unifying language, sharing, and understanding of desired outcomes, conducting cost-benefit analyses to minimise trade-offs, using multiple modes of communication for stakeholders, and applying research outcomes to inform regulation. It can be applied to improve collaboration among researchers, managers and planners from all realms, leading to strategic allocation of resources, increased protection of urban natural resources and improved environmental regulation with broad public support