Sydney Harbour: what we do and do not know about a highly diverse estuary

Abstract

Sydney Harbour is a global hotspot for marine and estuarine diversity. Despite its social, economic and biological value, the available knowledge has not previously been reviewed or synthesised. We systematically reviewed the published literature and consulted experts to establish our current understanding of the Harbour’s natural systems, identify knowledge gaps, and compare Sydney Harbour to other major estuaries worldwide. Of the 110 studies in our review, 81 focussed on ecology or biology, six on the chemistry, 10 on geology and 11 on oceanography. Subtidal rocky reef habitats were the most studied, with a focus on habitat forming macroalgae. In total 586 fish species have been recorded from the Harbour, which is high relative to other major estuaries worldwide. There has been a lack of process studies, and an almost complete absence of substantial time series that constrains our capacity to identify trends, environmental thresholds or major drivers of biotic interactions. We also highlight a lack of knowledge on the ecological functioning of Sydney Harbour, including studies on microbial communities. A sound understanding of the complexity, connectivity and dynamics underlying ecosystem functioning will allow further advances in management for the Harbour and for similarly modified estuaries around the world.

An evaluation of semi‐automated methods for collecting ecosystem‐level data in temperate marine systems

“…Our study area, Sydney Harbour, is a modified system, where centuries of human development interact with a diverse rocky shoreline. The state government of New South Wales have regularly mapped key habitats in coastal estuaries including Sydney Harbour from aerial imagery (Creese, Glasby, West, & Gallen, ), but community scale (<5–10 m) data are lacking (Hedge et al., ; Johnston et al., ; Mayer‐Pinto, Underwood, & Marzinelli, ; Mayer‐Pinto, Johnston et al., ). Sydney Harbour has worldwide recognition as an iconic and biologically diverse estuary, but has typically been the subject of studies dissecting the effects of contaminants, invasive species, and artificial structures on marine ecology (Johnston et al., ).…”

“…The state government of New South Wales have regularly mapped key habitats in coastal estuaries including Sydney Harbour from aerial imagery (Creese, Glasby, West, & Gallen, ), but community scale (<5–10 m) data are lacking (Hedge et al., ; Johnston et al., ; Mayer‐Pinto, Underwood, & Marzinelli, ; Mayer‐Pinto, Johnston et al., ). Sydney Harbour has worldwide recognition as an iconic and biologically diverse estuary, but has typically been the subject of studies dissecting the effects of contaminants, invasive species, and artificial structures on marine ecology (Johnston et al., ). Remnant inundated and semi‐inundated habitats in Sydney Harbour include a variety of rocky reef habitats, seagrasses, soft sediments, saltmarshes, and mangroves, while more than half of the natural shoreline has been converted to hard artificial structures (Mayer‐Pinto, Johnston et al., ).…”

“…Sydney Harbour has worldwide recognition as an iconic and biologically diverse estuary, but has typically been the subject of studies dissecting the effects of contaminants, invasive species, and artificial structures on marine ecology . Remnant inundated and semi-inundated habitats in Sydney Harbour include a variety of rocky reef habitats, seagrasses, soft sediments, saltmarshes, and mangroves, while more than half of the natural shoreline has been converted to hard artificial structures (Mayer-Pinto, Johnston et al, 2015). This study focuses on rocky reef habitat and the Common Kelp Ecklonia radiata (C. Agardh) J. Agardh, a dominant canopy forming algae on reefs in Southern Australia (Bennett et al, 2015).…”

“…It is likely that increased turbidity within the estuary and harbor also reduces the light attenuation depth (Mayer-Pinto, Johnston et al, 2015), in turn limiting kelp growth.…”

Assessing the Use of Area- and Time-Averaging Based on Known De-correlation Scales to Provide Satellite Derived Sea Surface Temperatures in Coastal Areas

“…A number of the loggers used in this study were deployed close to marine/tide dominated estuaries (e.g., Jervis Bay) with low and intermittent freshwater inflows (and thus shallow intermittent river plumes, e.g., Johnston et al, 2015). This is in agreement with Stobart et al (2016), who also found that the proximity to estuaries did not explain differences between in situ and satellite data in the vicinity of FIGURE 10 | Mean temperature differences between in situ and satellite that was processed at each logger location using an area average of 8 km across shelf and 20 km along shelf with a rolling mean based on the de-correlation time for the in situ location to fill in missing data (i.e.…”