Sydney Harbour: a review of anthropogenic impacts on the biodiversity and ecosystem function of one of the world

Abstract

Sydney Harbour is a hotspot for diversity. However, as with estuaries worldwide, its diversity and functioning faces increasing threats from urbanisation. This is the first synthesis of threats and impacts in Sydney Harbour. In total 200 studies were reviewed: 109 focussed on contamination, 58 on habitat modification, 11 addressed non-indigenous species (NIS) and eight investigated fisheries. Metal concentrations in sediments and seaweeds are among the highest recorded worldwide and organic contamination can also be high. Contamination is associated with increased abundances of opportunistic species, and changes in benthic community structure. The Harbour is also heavily invaded, but invaders’ ecological and economic impacts are poorly quantified. Communities within Sydney Harbour are significantly affected by extensive physical modification, with artificial structures supporting more NIS and lower diversity than their natural equivalents. We know little about the effects of fishing on the Harbour’s ecology, and although ocean warming along Sydney is among the fastest in the world, we know little about how the ecosystem will respond to warming. The interactive and cumulative effects of stressors on ecosystem functioning and services in the Harbour are largely unknown. Sustainable management of this iconic natural system requires that knowledge gaps are addressed and translated into coherent environmental plans.

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

“…Exposure to waves and water movement can influence kelp structure (Fowler‐Walker, Wernberg, & Connell, ) and community processes (Wernberg & Connell, ), which may contribute to the shallow limit of kelp survival within the sheltered harbor. It is likely that increased turbidity within the estuary and harbor also reduces the light attenuation depth (Mayer‐Pinto, Johnston et al., ), in turn limiting kelp growth.…”

“…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., ).…”

“…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., ). 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., ).…”

Towards Sustainable Environmental Quality: Priority Research Questions for the Australasian Region of Oceania

“…Countries in the region have iconic landscapes with unique flora and fauna. Interconnections among stressors from landscape development and urbanization across freshwater to marine gradients are widespread in this region (e.g., Mayer-Pinto et al 2015;Weeks et al 2016), where the vast majority of human populations reside within 50 km from the coast. Biodiversity hotspots are prevalent, as are freshwater and marine ecosystems (e.g., the Great Barrier Reef), which are susceptible to stress from anthropogenic activities, including climate change (Adams et al 2016).…”

Interdecadal changes in the community, population and individual levels of the fish fauna of an extensively modified estuary

“…The extreme and growing stressors on urbanized estuaries resulting from high population growth in the coastal zone (Kennish, 2002;Elliott & Whitfield, 2011;Jennerjahn & Mitchell, 2013), as well as climate change effects (Scavia et al, 2002;Statham, 2012;Wetz & Yoskowitz, 2013), are well documented worldwide. Copious examples of the ecosystem services threatened or lost through the degradation of these highly productive environments are also provided throughout the ecological literature (Lotze et al, 2006;Davis & Kidd, 2012;Mayer-Pinto et al, 2015).…”