Effect of wharves on intertidal assemblages on seawalls in Sydney Harbour, Australia

Blockley, David J.

doi:10.1016/j.marenvres.2006.10.007

Cited by 31 publications

(21 citation statements)

References 37 publications

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“…These included barnacles and tubeworms, but also rarer species of bryozoans, ascidians and sponges. Many of these taxa are absent from the normal façades of seawalls, although a few are found at very lowshore levels or where walls are shaded by wharves (Blockley 2007). These structures therefore had the desired eVect of increasing the number of species that inhabited the wall compared to those found on the normal façade.…”

Section: Discussionmentioning

confidence: 99%

“…The vertical surfaces were not speciWcally designed to represent natural habitats, but may mimic vertical walls of deep crevices and caves. They were expected to increase diversity because they are shaded, and walls under wharves have diVerent assemblages to those on walls that are not shaded by wharves (Blockley and Chapman 2006;Blockley 2007).…”

Section: Methodsmentioning

confidence: 99%

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Engineering novel habitats on urban infrastructure to increase intertidal biodiversity

2009

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Urbanization replaces natural shorelines with built infrastructure, seriously impacting species living on these "new" shores. Understanding the ecology of developed shorelines and reducing the consequences of urban development to fauna and flora cannot advance by simply documenting changes to diversity. It needs a robust experimental programme to develop ways in which biodiversity can be sustained in urbanized environments. There have, however, been few such experiments despite wholesale changes to shorelines in urbanized areas. Seawalls--the most extensive artificial infrastructure--are generally featureless, vertical habitats that support reduced levels of local biodiversity. Here, a mimic of an important habitat on natural rocky shores (rock-pools) was experimentally added to a seawall and its impact on diversity assessed. The mimics created shaded vertical substratum and pools that retained water during low tide. These novel habitats increased diversity of foliose algae and sessile and mobile animals, especially higher on the shore. Many species that are generally confined to lowshore levels, expanded their distribution over a greater tidal range. In fact, there were more species in the constructed pools than in natural pools of similar size on nearby shores. There was less effect on the abundances of mobile animals, which may be due to the limited time available for recruitment, or because these structures did not provide appropriate habitat. With increasing anthropogenic intrusion into natural areas and concomitant loss of species, it is essential to learn how to build urban infrastructure that can maintain or enhance biodiversity while meeting societal and engineering criteria. Success requires melding engineering skills and ecological understanding. This paper demonstrates one cost-effective way of addressing this important issue for urban infrastructure affecting nearshore habitats.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Engineering novel habitats on urban infrastructure to increase intertidal biodiversity

2009

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“…Results derived from saltmarshes (Sanger, Holland & Gainey ; Struck et al . ), seagrass beds (Burdick & Short ; Shafer ), estuaries (Able, Manderson & Studholme ) and hard substrates (Glasby ; Blockley ) consistently show negative effects of shading by artificial structures on autotrophs and alterations in the structure of biological communities. Specifically on hard substrates, artificial shading has been associated with shifts in the structure and the diversity of the community, by reducing macroalgae cover (Glasby ; Blockley & Chapman ; Blockley ; Miller & Etter ) and also by increasing the overall abundances of some filter‐feeding invertebrates and mobile consumers (Glasby ; Takada ; Blockley ; Miller & Etter ).…”

Section: Introductionmentioning

confidence: 99%

Shading impacts by coastal infrastructure on biological communities from subtropical rocky shores

Pardal

Dias

Jenkins

et al. 2016

Journal of Applied Ecology

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Summary1. Artificial shading has been highlighted as an important human disturbance, affecting both productivity and community organization. However, studies of shading have been poorly explored from an environmental impact perspective. 2. We compared community structure on subtropical rocky shores in areas shaded by human constructions with those in unshaded areas. We then implemented a manipulative field experiment to determine the effects of shading on the macrobenthic community, biofilm biomass and larval recruitment. 3. Shading consistently affected the biological community of rocky shores. The biomass and cover of macroalgae and the size of most sedentary grazers were smaller in shaded habitat. In the infralittoral fringe, we recorded a shift in dominance from macroalgae in unshaded habitats to invertebrate filter feeders in shaded ones. In a similar way, the community from the mesolittoral was also affected by shading but not at all locations. 4. Experimental manipulation of shading led to a total loss of macroalgae from the infralittoral fringe and no community replacement over a period of 220 days. In the mesolittoral, oysters became more abundant in shaded conditions, while barnacles decreased in abundance. Larval recruitment was also affected, with oysters and barnacles recruiting more in shaded habitats. 5. Synthesis and applications. We demonstrate a clear impact of shading by artificial humanmade structures on patterns and processes regulating biodiversity on rocky shores and thus consequences for coastal ecosystem functioning. We argue that shading by artificial coastal structures, such as those proposed in the port expansion in our study site in south-eastern Brazil, is potentially underestimated. Our work emphasizes the importance of careful evaluations of artificial structures in order to promote sustainable coastal development. As a result, we do not recommend the proposed expansion by suspended structures of the port of São Sebastião, as the consequent shading will negatively affect the biodiversity and ecosystem functioning of the Arac ß a Bay and surrounding areas.

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“…wood, concrete) and cause shade (e.g. piers) [10], [11]. These structures support assemblages different from those in many natural habitats [12], [13], [14].…”

Section: Introductionmentioning

confidence: 99%

Modified Habitats Influence Kelp Epibiota via Direct and Indirect Effects

2011

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Addition of man-made structures alters abiotic and biotic characteristics of natural habitats, which can influence abundances of biota directly and/or indirectly, by altering the ecology of competitors or predators. Marine epibiota in modified habitats were used to test hypotheses to distinguish between direct and indirect processes. In Sydney Harbour, kelps on pier-pilings supported greater covers of bryozoans, particularly of the non-indigenous species Membranipora membranacea, than found on natural reefs. Pilings influenced these patterns and processes directly due to the provision of shade and indirectly by altering abundances of sea-urchins which, in turn, affected covers of bryozoans. Indirect effects were more important than direct effects. This indicates that artificial structures affect organisms living on secondary substrata in complex ways, altering the biodiversity and indirectly affecting abundances of epibiota. Understanding how these components of habitats affect ecological processes is necessary to allow sensible prediction of the effects of modifying habitats on the ecology of organisms.

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Effect of wharves on intertidal assemblages on seawalls in Sydney Harbour, Australia

Cited by 31 publications

References 37 publications

Engineering novel habitats on urban infrastructure to increase intertidal biodiversity

Engineering novel habitats on urban infrastructure to increase intertidal biodiversity

Shading impacts by coastal infrastructure on biological communities from subtropical rocky shores

Modified Habitats Influence Kelp Epibiota via Direct and Indirect Effects

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