Fish assemblages associated with coastal defence structures: Does the surrounding habitat matter?

Franzitta, Giulio; Airoldi, Laura

doi:10.1016/j.rsma.2019.100743

“…This suggests that eco-engineering tests aiming to enhance the ecological performance of artificial habitats should also pay attention to other structural and non-structural elements that have been reported to differ between artificial and natural habitats, but which so far have been largely neglected (Airoldi et al, 2021). These elements include among others: construction material (Glasby, 2000;Sella and Perkol Finkel, 2015;McManus et al, 2018); careful planning of maintenance (Airoldi and Bulleri, 2011); distance from pollution sources (Strain et al, 2021); position (Glasby and Connell, 2001;Moschella et al, 2005); and the environmental (Franzitta and Airoldi, 2019), biotic (e.g., predation pressure Ferrario et al, 2016;Gianni et al, 2018), and social (Strain et al, 2019) settings. It is also important to consider that our study covered only about 8 km of coastlines in a region characterized by small tides and moderate wave action, which may affect the design of artificial structures.…”

Section: Discussionmentioning

confidence: 99%

“…We also noticed that topographic heterogeneity was especially emphasized as a limiting factor for the biota by papers dealing with morphologically regular seawalls (Bulleri and Chapman, 2004;Bulleri, 2005;Morris et al, 2017). Conversely, papers dealing with irregular infrastructures (i.e., built with quarried rocks or molded concrete elements) highlighted other potentially limiting factors for the biota, including greater pressures from fish (Ferrario et al, 2016;Gianni et al, 2018), greater disturbances (Airoldi and Bulleri, 2011), or a greater influence of the surrounding sedimentary environment (Franzitta and Airoldi, 2019;Komyakova et al, 2019). Finally, although physical habitat structure affects organisms differently at multiple spatial scales (Kovalenko et al, 2012;Loke et al, 2015), multi-scale measurements are still rare in artificial habitats, and most studies have focused on very small spatial scales from centimeters to meters (Strain et al, 2018b).…”

Section: Introductionmentioning

confidence: 92%

How and to What Degree Does Physical Structure Differ Between Natural and Artificial Habitats? A Multi-Scale Assessment in Marine Intertidal Systems

Grasselli

¹

,

Airoldi

²

2021

Self Cite

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Marine infrastructures are increasing, generating a variety of impacts and introducing artificial habitats which have low ecological value and support assemblages that differ significantly from those on natural rocky coasts. While in the past there was little ecological consideration as to how artificial structures were built, now the trend is to look for “greener” designs inspired by or mimicking nature. These greening efforts have had a strong focus on enhancing physical habitat structure to support more diverse assemblages, driven by the untested assumption that artificial habitats lack the physical structure proper to natural habitats. We tested this assumption by comparing five descriptors of physical structure (inclination; exposure; roughness; abundance, and diversity of surface morphological microelements) across a combination of natural and artificial habitats of regular and irregular morphologies (seawalls = artificial regular; cliffs = natural regular; breakwaters = artificial, irregular; and boulder fields = natural irregular) in the North Adriatic Sea. Most structural descriptors were similar between artificial and natural habitats. Only inclination was consistently steeper in the artificial than in the natural habitats. Other minor differences in roughness or in the abundance of some surface microelements were related to the general morphology (regular or irregular) of the habitat rather than to its artificial or natural identity. The outcomes challenge the widespread assumption that artificial habitats lack the physical structure proper to natural habitats and stimulate renewed consideration about other structural and non-structural elements that could enhance the performance and sustainability of artificial marine structures, such as construction material, environmental setting or maintenance. They also encourage a wider reflection about what makes an artificial building surface “greener”: structural complexity is an important ecological parameter, and its deliberate increase will lead to responses in the biota, however, this may not necessarily match “more natural” conditions.

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“…UVC involved a fish count along three transects of 25 m in length and 5 m in width (Harmelin-Vivien et al, 1985) in each area. In order to limit the effect of the operator on fish behaviour, data collection was performed simultaneously with the deposition of a metric string on the seabed to precisely define the length of the transects (Kulbicki, 1998;Edgar et al, 2004;Dickens et al, 2011;Franzitta et al, 2019), while its width was visually estimated. The speed along the transect was kept to about 3-4 m per minute.…”

Section: Uvc Techniquementioning

confidence: 99%

Performance of a baited underwater video system vs. the underwater visual census technique in assessing the structure of fish assemblages in a Mediterranean marine protected area

Manna¹,

Guala²,

Grech

³

et al. 2021

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Accurate, rapid and cost-effective fish assemblage monitoring is fundamental for marine protected area (MPA) management as a pivotal tool to verify whether and to what extent MPA conservation objectives have been achieved and to redefine these objectives in the framework of an adaptive management. Recently, there has been a sharp increase in the number of video-based methods to study fish fauna, such as baited remote underwater video (BRUV) systems, that, depending on the objectives of the monitoring, can provide complementary or additional data to the more commonly used underwater visual census (UVC). Even though BRUV systems have been widely used in a wide range of geographic contexts and habitats, their use in the Mediterranean basin is still sporadic and the evaluation of the efficiency of BRUV systems and whether they can be used to complement other techniques needs investigation. Thus, the objective of this study was to assess the performance of a BRUV system in a Mediterranean MPA and to evaluate its effectiveness in assessing the structure of fish assemblages (abundance and species richness) by comparing estimates with those obtained by the UVC technique. The fish fauna were monitored by BRUV and UVC in the Capo Caccia – Isola Piana Marine Protected Area (Sardinia, Italy), in July and October-November 2020, at four sampling sites and two areas, hundreds of meters apart, for each site. Overall, 46 taxa and a total of 3620 individuals were observed by BRUV, while 36 taxa and a total of 2995 individuals were observed by UVC. The species first observed in front of the camera’s field of view and able to reach the maximum abundance were the planktivores (Chromis chromis and Oblada melanura) followed by several carnivorous species belonging to the families Labridae, Serranidae and Sparidae, and lastly two carnivores (Mullus surmuletus and Mugilidae spp.) and some high-level predators (Dentex dentex, Seriola dumerili, Sphyraena viridensis, Dicentrarchus labrax). The maximum species richness and abundance were reached between 39 and 50 min. The cumulative species richness increased until around 30 min. Species richness was higher during the BRUV compared to the UVC monitoring. The consistency in findings between BRUV and UVC and a better performance of BRUV in detecting some species (mainly high-level predators), supports BRUV as an additional technique for describing and quantifying species richness and abundance also in the Mediterranean Sea. Based on the results of this study, the advantages/disadvantages, shortcomings, suggestions and resources needed for the two techniques are outlined.

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“…This suggests that eco-engineering tests aiming to enhance the ecological performance of artificial habitats should also pay attention to other structural and non-structural elements that have been reported to differ between artificial and natural habitats, but which so far have been largely neglected (Airoldi et al, 2021). These elements include among others: construction material (Glasby, 2000;Sella and Perkol Finkel, 2015;McManus et al, 2018); careful planning of maintenance (Airoldi and Bulleri, 2011); distance from pollution sources (Strain et al, 2021); position (Glasby and Connell, 2001;Moschella et al, 2005); and the environmental (Franzitta and Airoldi, 2019), biotic (e.g., predation pressure Ferrario et al, 2016;Gianni et al, 2018), and social (Strain et al, 2019) settings. It is also important to consider that our study covered only about 8 km of coastlines in a region characterized by small tides and moderate wave action, which may affect the design of artificial structures.…”

Section: Discussionmentioning

confidence: 99%

“…We also noticed that topographic heterogeneity was especially emphasized as a limiting factor for the biota by papers dealing with morphologically regular seawalls (Bulleri and Chapman, 2004;Bulleri, 2005;Morris et al, 2017). Conversely, papers dealing with irregular infrastructures (i.e., built with quarried rocks or molded concrete elements) highlighted other potentially limiting factors for the biota, including greater pressures from fish (Ferrario et al, 2016;Gianni et al, 2018), greater disturbances (Airoldi and Bulleri, 2011), or a greater influence of the surrounding sedimentary environment (Franzitta and Airoldi, 2019;Komyakova et al, 2019). Finally, although physical habitat structure affects organisms differently at multiple spatial scales (Kovalenko et al, 2012;Loke et al, 2015), multi-scale measurements are still rare in artificial habitats, and most studies have focused on very small spatial scales from centimeters to meters (Strain et al, 2018b).…”

Section: Introductionmentioning

confidence: 92%

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Fish assemblages associated with coastal defence structures: Does the surrounding habitat matter?

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References 57 publications

How and to What Degree Does Physical Structure Differ Between Natural and Artificial Habitats? A Multi-Scale Assessment in Marine Intertidal Systems

How and to What Degree Does Physical Structure Differ Between Natural and Artificial Habitats? A Multi-Scale Assessment in Marine Intertidal Systems

Performance of a baited underwater video system vs. the underwater visual census technique in assessing the structure of fish assemblages in a Mediterranean marine protected area

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