Recruitment determines differences between assemblages on shaded or unshaded seawalls

Blockley, David J.; Chapman, M. G.

doi:10.3354/meps327027

Cited by 32 publications

(25 citation statements)

References 32 publications

(58 reference statements)

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“…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%

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: Methodsmentioning

confidence: 99%

Engineering novel habitats on urban infrastructure to increase intertidal biodiversity

2009

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“…The environmental factors that are the most strongly modified in marinas include temperature, salinity, hydrodynamics, sediment resuspension, contaminants, and light (Dafforn et al, 2015). For instance, the network of pilings, pontoons, and poorly sloped seawalls modifies the light environment and contributes to the reduction in cover of habitatforming macrophytes (Blockley & Chapman, 2006;Bulleri & Chapman, 2010), either directly, by affecting their recruitment and performance, or indirectly, by favoring the recruitment of epibionts (Marzinelli, Underwood, & Coleman, 2011). Although the reduction or loss of natural seaweed habitats (canopy and understory) may affect associated faunal assemblages, the spatial arrangement of artificial structures creates myriad microhabitats with various structures, properties, and ultimately complexities (Dafforn et al, 2015) that may favor alternative (mostly faunal) habitat-forming species (Connell, 2001b;Sellheim, Stachowicz, & Coates, 2010), including NIS (Dafforn, 2017).…”

Section: Introductionmentioning

confidence: 99%

Habitat formation prevails over predation in influencing fouling communities

Leclerc

Viard

2017

Ecology and Evolution

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Coastal human‐made structures, such as marinas and harbors, are expanding worldwide. Species assemblages described from these artificial habitats are novel relative to natural reefs, particularly in terms of the abundance of nonindigenous species (NIS). Although these fouling assemblages are clearly distinctive, the ecosystem functioning and species interactions taking place there are little understood. For instance, large predators may influence the fouling community development either directly (feeding on sessile fauna) or indirectly (feeding on small predators associated with these assemblages). In addition, by providing refuges, habitat complexity may modify the outcome of species interactions and the extent of biotic resistance (e.g., by increasing the abundance of niche‐specific competitors and predators of NIS). Using experimental settlement panels deployed in the field for 2.5 months, we tested the influence of predation (i.e., caging experiment), artificial structural complexity (i.e., mimics of turf‐forming species), and their interactions (i.e., refuge effects) on the development of sessile and mobile fauna in two marinas. In addition, we tested the role of biotic complexity—arising from the habitat‐forming species that grew on the panels during the trial—on the richness and abundance of mobile fauna. The effect of predation and artificial habitat complexity was negligible, regardless of assemblage status (i.e., native, cryptogenic, and nonindigenous). Conversely, habitat‐forming species and associated epibionts, responsible for biotic complexity, had a significant effect on mobile invertebrates (richness, abundance, and community structure). In particular, the richness and abundance of mobile NIS were positively affected by biotic complexity, with site‐dependent relationships. Altogether, our results indicate that biotic complexity prevails over artificial habitat complexity in determining the distribution of mobile species under low predation pressure. Facilitation of native and non‐native species thus seems to act upon diversity and community development: This process deserves further consideration in models of biotic resistance to invasion in urban marine habitats.

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“…Sunlight limitation can influence animal communities by affecting physical conditions (e.g. reducing heat stress) (Williams 1994;Kon, Kurokura & Tongnunui 2010), decreasing energetic resources of herbivores (Hill, Ryon & Schilling 1995;Harley 2002) and influencing larval recruitment of marine organisms (Thorson 1964;Saunders & Connell 2001;Blockley & Chapman 2006).…”

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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Recruitment determines differences between assemblages on shaded or unshaded seawalls

Cited by 32 publications

References 32 publications

Engineering novel habitats on urban infrastructure to increase intertidal biodiversity

Engineering novel habitats on urban infrastructure to increase intertidal biodiversity

Habitat formation prevails over predation in influencing fouling communities

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

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