Nicolas Desroy - Academia.edu (original) (raw)

Papers by Nicolas Desroy

DESCRIPTION Les travaux de la Station marine du Muséum National d’Histoire Naturelle de Dinard, e... more DESCRIPTION Les travaux de la Station marine du Muséum National d’Histoire Naturelle de Dinard, et notamment de Fournier et al. (2003, 2004, 2005, 2009), Godet et al. (2008, 2009) et Toupoint et al. (2006, 2008) ont permis de caractériser les habitats intertidaux sablo-vaseux de l’archipel de Chausey. Ces connaissances ont d’ailleurs été utilisées pour les DOCOB Habitats, ZPS et NATURA2000 de Chausey, mais également dans la réflexion cadre du plan de gestion du Conservatoire du littoral. Le domaine subtidal restait, quant à lui, beaucoup moins connu. Les données historiques étant quasi inexistantes, il est apparu indispensable de conduire une prospection de ce domaine. Si en termes d’habitats, il est probable que les assemblages de sédiments identifiés et cartographiés en zone intertidale se prolongent en domaine subtidal, il a semblé nécessaire de le confirmer par une nouvelle campagne d’acquisition de données biologiques et sédimentaires. L'objectif de cette action, qui s’inscrit dans le cadre du programme HEIMa (Habitats, Espèces et Interactions Marines), est donc de disposer d’une cartographie des principaux assemblages morpho-sédimentaires et des unités de peuplements benthiques associées dépendant de ces biotopes afin de suivre la dynamique évolutive des milieux et des espèces, de juger des effets des pressions rencontrées et de permettre aux gestionnaires de définir des problématiques de conservation.

Le present protocole detaille le planning, les periodes et les methodes de prelevement des macroi... more Le present protocole detaille le planning, les periodes et les methodes de prelevement des macroinvertebres benthiques de substrat meuble des facades Manche et Atlantique dans le cadre de la DCE. Il precise egalement les techniques d'analyse des echantillons et le mode de bancarisation des donnees.

The English Channel is a megatidal sea characterized by large tidal currents in which the larvae ... more The English Channel is a megatidal sea characterized by large tidal currents in which the larvae of Pectinaria koreni are dispersed on a large spatial scale by tidal currents. They settle abundantly on a wide edaphic spectrum, but the populations of adults are confined to bays and estuaries. Laboratory experiments under still water and flume flows showed that post-larvae of P. koreni were able to actively select a suitable substrate i) on a macrospatial scale by resuspending themselves in the water column; ii) on a microspatial scale by crawling at the sediment surface. Adults also influenced the post-larvae habitat selection. When post-larvae settle on a suitable sediment in presence of adults, they resuspend themselves immediately. This resuspension phenomenon is a consequence of bioturbation by the adults (subsurface deposit feeders) whose vertical movement and feeding activity are mainly dependent on hydrodynamic conditions. However, in the presence of Owenia fusiformis adults (...

La coquille Saint-Jacques europeenne Pecten maximus constitue pour les pecheries francaises la pr... more La coquille Saint-Jacques europeenne Pecten maximus constitue pour les pecheries francaises la premiere espece debarquee en tonnage, et la deuxieme ou troisieme en valeur. La Manche represente plus de 90% de ces debarquements : l’exploitation de cette espece y est donc vitale pour les flottilles riveraines. Le projet COMANCHE (Interactions ecosystemiques et impacts anthropiques dans les populations de COquilles Saint-Jacques de la MANCHE) se proposait d’ameliorer la connaissance de la coquille Saint-Jacques a l’echelle de l’ensemble de la Manche, a travers une approche ecosystemique des pecheries, en faisant appel a un large eventail de disciplines scientifiques (physique, chimie, genetique, ecologie, geostatistique, modelisation, economie….) : localisation spatiale des gisements, connectivite entre gisements par derive larvaire, variabilite des traits de vie et du recrutement, dynamique des communautes planctoniques et determinisme des efflorescences d’algues toxiques, place de ce ...

Ce document constitue le rapport final etabli dans le cadre de la convention de partenariat etabl... more Ce document constitue le rapport final etabli dans le cadre de la convention de partenariat etablie avec l'Agence de aires marines protegees – Mission d'etude du golfe normand-breton relative a la conduite d'un suivi scientifique de l’etat de conservation des recifs d’hermelles (Sabellaria alveolata) prevu dans le cadre du projet Life 12 ENV/FR/316 – Experimentation pour une gestion durable et concertee de la peche a pied de loisir – LIFE+ Peche a pied de loisir . Ce rapport presente : · le protocole de suivi de terrain des recifs d’hermelles incluant les procedures de travail et strategie d'echantillonnage de terrain (fiches protocoles - detaillee et condensee - et fiches de saisie de donnees), les parametres de suivi des recifs d’hermelles, les methodes de traitements et de calcul des indicateurs ; · l'evolution des etats ecologiques des recifs d’hermelles sur les deux sites de la Baie du Mont-Saint- Michel (Sainte-Anne et Champeaux-Fregate) en tenant compte d’...

This progress report summarizes actual advancements (February 2007) in order to propose a monitor... more This progress report summarizes actual advancements (February 2007) in order to propose a monitoring benthic network according to the European Water Framework Directive for the area concerned by the Seine-Normandie water district Mots-clés Directive Cadre Eau, Benthos, Réseau de surveillance, Manche Words keys European Water Framework Directive, Benthos, Monitoring Network, the Channel

In the eastern Bay of Seine, which is a representative area of coastal zones exposed to numerous ... more In the eastern Bay of Seine, which is a representative area of coastal zones exposed to numerous anthropogenic disturbances, data from a long-term monitoring program of the benthic macrofauna based on a framework of 60 stations sampled during 7 cruises from 1988 to 2016 were used to investigate the link between species and functional diversity at different scales and assess how long-term changes in the community structure may have altered the ecosystem functioning. To cover the different facets of α-diversity, a selection of species and functional diversity indices were calculated and the links between these metrics were determined from a Principal Component Analysis. The β-diversity was analysed by applying multivariate methods on both species and traits composition matrices. Population fluctuations of a few very abundant species led to the major variations observed in the structure of the community in both taxonomic and functional aspects. A certain redundancy was found among spec...

ICES Journal of Marine Science

Species ranges are shifting globally to track temperature changes in response to climate warming,... more Species ranges are shifting globally to track temperature changes in response to climate warming, with substantial variability among taxa. In the English Channel, a biogeographical transition zone between the cold temperate and warm temperate provinces of the North-East Atlantic, distribution shifts have been relatively well documented for plankton, fish and intertidal benthic organisms, but little information is available on sublittoral benthos. Following a description of the magnitude of the sea bottom temperature (SBT) rise, the changes in the distribution and occupancy of 65 benthic invertebrate species were analysed by comparing data collected throughout the English Channel at more than 200 stations sampled during a cool period in the 1960s–1970s and at present in 2012–2014. A non-uniform rise in SBT for the last three decades was observed at the regional scale, varying from 0.07 to 0.54°C per decade. This rise differs from that reported for sea surface temperature (SST) in str...

Ecological Modelling

In order to better understand and predict the dynamics of benthic macroinvertebrate communities, ... more In order to better understand and predict the dynamics of benthic macroinvertebrate communities, we need to first define the functional components of benthic biodiversity and then provide a mechanistic description of how they interact with their abiotic environment, their basic resources and each other. These interactions should be largely controlled by readily available biological traits, making trait-based modelling an ideal framework for the synthesis of relevant hypotheses from ecological theory and expert knowledge. With the help of benthic species traits, we derived a set of first principles regarding the role of organisms in processes of environmental filtering, consumption of algae/detritus, predation, use of space, biogenic habitat modification and trade-offs in the utilization and allocation of resources. These principles were incorporated into qualitative models in the form of functional relationships linking groups of benthic organisms in the Rance estuary (Brittany, France). The general stability of these models illustrates their potential to persist in time and to constitute a plausible representation of the natural world. Their structure provides insight into the role of various community assembly mechanisms and the direction that the system might take in response to perturbations. The results are expected to inform the development of quantitative models reproducing the spatial and temporal dynamics of marine benthic biodiversity in the Rance estuary. Highlights ► We derived first principles on the role of benthic organisms in community assembly. ► These principles dictated functional relationships among groups of benthic species. ► Groups and functional relationships comprised qualitative models of benthic systems. ► Stability analysis supported the models' potential to represent benthic communities. ► Model structure offered insight into the role of some community assembly mechanisms.

Estuarine, Coastal and Shelf Science, 2016

The relationship between foraging shorebirds, macrobenthos and sedimentary parameters has been wi... more The relationship between foraging shorebirds, macrobenthos and sedimentary parameters has been widely studied across Western Europe. Megatidal areas have large zones uncovered when the water retreats. Consequently, in such cases, the tide also influences foraging activities. This paper examines the use of an intertidal space by waders to define how macrobenthic resource concentrates foraging activity of birds in a large megatidal sandflat. This approach combines accurate spatial distribution of waders (Oystercatcher, Eurasian curlew, Bar-tailed Godwit and Redknot) according to their activity with ecological/biological parameters. A differential exploitation of the flat is clearly shown, with macrobenthic biomass appearing as one of the main explanatory factor for the four species considered on the western part of the bay and altitude (shore elevation) in the eastern part. The novelty of this study relates to the large area, also presumed to be a functional unit, while considering at the same time the singularities of the different parts of the flat. This multi-scale approach identifies important factors influencing the differential distribution patterns observed. The different selected parameters present an important variability in their contribution, underlining the complexity of explaining the distribution of foraging birds. Consequently, the study of such complex phenomena needs to consider additional variables to improve the relevance of explanatory models. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Ce rapport présente les résultats des opérations menées en 2008 (contrôle de surveillance du comp... more Ce rapport présente les résultats des opérations menées en 2008 (contrôle de surveillance du compartiment benthique : macroinvertébrés benthiques et macroalgues), sur l'ensemble des masses d'eau côtières et de transitions rattachées au district Artois-Picardie.

Journal of Sea Research, 2004

Growth, condition, diet and spatial distribution of the solenette Buglossidium luteum (Risso, 181... more Growth, condition, diet and spatial distribution of the solenette Buglossidium luteum (Risso, 1810) were investigated along the coasts of the French Atlantic, eastern English Channel and Southern Bight of the North Sea. Distribution and habitat preferences of solenette were analysed in relation to physical and biological features presumed to influence fish distribution. B. luteum was patchily distributed and concentrated in shallow muddy and muddy-sand bottoms moderately influenced by estuarine waters (euhaline waters). In the studied area, solenette seemed to find habitats suitable for growth. Food availability was not assumed to be a limiting factor for solenette distribution in contrast to abiotic factors such as salinity.

Journal of Sea Research, 2004

Growth, condition, diet and spatial distribution of the solenette Buglossidium luteum (Risso, 181... more Growth, condition, diet and spatial distribution of the solenette Buglossidium luteum (Risso, 1810) were investigated along the coasts of the French Atlantic, eastern English Channel and Southern Bight of the North Sea. Distribution and habitat preferences of solenette were analysed in relation to physical and biological features presumed to influence fish distribution. B. luteum was patchily distributed and concentrated in shallow muddy and muddy-sand bottoms moderately influenced by estuarine waters (euhaline waters). In the studied area, solenette seemed to find habitats suitable for growth. Food availability was not assumed to be a limiting factor for solenette distribution in contrast to abiotic factors such as salinity.

Estuarine, Coastal and …, 2011

Coastal bays provide habitats for juveniles and adults of many marine species. Mont Saint-Michel ... more Coastal bays provide habitats for juveniles and adults of many marine species. Mont Saint-Michel Bay (MSMB, France) hosts a highly diversified fish community and constitutes one of the most important nursery grounds for many commercially exploited marine species, such as sea ...

Marine Environmental Research

ICES Journal of Marine Science

Although colonization of artificial structures by epibenthic communities is well-documented overa... more Although colonization of artificial structures by epibenthic communities is well-documented overall, our understanding of colonization processes is largely limited to low-energy environments. In this study, we monitored epibenthic colonization of different structures associated with a tidal energy test site located in a high-energy hydrodynamic environment. Using four years of image-based underwater surveys, we characterized changes through space and time in the taxonomic composition of epibenthic assemblages colonizing two kinds of artificial structures, as well as the surrounding natural habitat. Our results highlight that ecological successions followed similar trends across the two artificial habitats, but that different habitat-specific communities emerged at the end of our survey. Deployment of these artificial structures resulted in the addition of elevated and stable substrata in an environment where natural hard substrates are unstable and strongly exposed to sediment abras...

DESCRIPTION Les travaux de la Station marine du Muséum National d’Histoire Naturelle de Dinard, e... more DESCRIPTION Les travaux de la Station marine du Muséum National d’Histoire Naturelle de Dinard, et notamment de Fournier et al. (2003, 2004, 2005, 2009), Godet et al. (2008, 2009) et Toupoint et al. (2006, 2008) ont permis de caractériser les habitats intertidaux sablo-vaseux de l’archipel de Chausey. Ces connaissances ont d’ailleurs été utilisées pour les DOCOB Habitats, ZPS et NATURA2000 de Chausey, mais également dans la réflexion cadre du plan de gestion du Conservatoire du littoral. Le domaine subtidal restait, quant à lui, beaucoup moins connu. Les données historiques étant quasi inexistantes, il est apparu indispensable de conduire une prospection de ce domaine. Si en termes d’habitats, il est probable que les assemblages de sédiments identifiés et cartographiés en zone intertidale se prolongent en domaine subtidal, il a semblé nécessaire de le confirmer par une nouvelle campagne d’acquisition de données biologiques et sédimentaires. L'objectif de cette action, qui s’inscrit dans le cadre du programme HEIMa (Habitats, Espèces et Interactions Marines), est donc de disposer d’une cartographie des principaux assemblages morpho-sédimentaires et des unités de peuplements benthiques associées dépendant de ces biotopes afin de suivre la dynamique évolutive des milieux et des espèces, de juger des effets des pressions rencontrées et de permettre aux gestionnaires de définir des problématiques de conservation.

Le present protocole detaille le planning, les periodes et les methodes de prelevement des macroi... more Le present protocole detaille le planning, les periodes et les methodes de prelevement des macroinvertebres benthiques de substrat meuble des facades Manche et Atlantique dans le cadre de la DCE. Il precise egalement les techniques d'analyse des echantillons et le mode de bancarisation des donnees.

The English Channel is a megatidal sea characterized by large tidal currents in which the larvae ... more The English Channel is a megatidal sea characterized by large tidal currents in which the larvae of Pectinaria koreni are dispersed on a large spatial scale by tidal currents. They settle abundantly on a wide edaphic spectrum, but the populations of adults are confined to bays and estuaries. Laboratory experiments under still water and flume flows showed that post-larvae of P. koreni were able to actively select a suitable substrate i) on a macrospatial scale by resuspending themselves in the water column; ii) on a microspatial scale by crawling at the sediment surface. Adults also influenced the post-larvae habitat selection. When post-larvae settle on a suitable sediment in presence of adults, they resuspend themselves immediately. This resuspension phenomenon is a consequence of bioturbation by the adults (subsurface deposit feeders) whose vertical movement and feeding activity are mainly dependent on hydrodynamic conditions. However, in the presence of Owenia fusiformis adults (...

La coquille Saint-Jacques europeenne Pecten maximus constitue pour les pecheries francaises la pr... more La coquille Saint-Jacques europeenne Pecten maximus constitue pour les pecheries francaises la premiere espece debarquee en tonnage, et la deuxieme ou troisieme en valeur. La Manche represente plus de 90% de ces debarquements : l’exploitation de cette espece y est donc vitale pour les flottilles riveraines. Le projet COMANCHE (Interactions ecosystemiques et impacts anthropiques dans les populations de COquilles Saint-Jacques de la MANCHE) se proposait d’ameliorer la connaissance de la coquille Saint-Jacques a l’echelle de l’ensemble de la Manche, a travers une approche ecosystemique des pecheries, en faisant appel a un large eventail de disciplines scientifiques (physique, chimie, genetique, ecologie, geostatistique, modelisation, economie….) : localisation spatiale des gisements, connectivite entre gisements par derive larvaire, variabilite des traits de vie et du recrutement, dynamique des communautes planctoniques et determinisme des efflorescences d’algues toxiques, place de ce ...

Ce document constitue le rapport final etabli dans le cadre de la convention de partenariat etabl... more Ce document constitue le rapport final etabli dans le cadre de la convention de partenariat etablie avec l'Agence de aires marines protegees – Mission d'etude du golfe normand-breton relative a la conduite d'un suivi scientifique de l’etat de conservation des recifs d’hermelles (Sabellaria alveolata) prevu dans le cadre du projet Life 12 ENV/FR/316 – Experimentation pour une gestion durable et concertee de la peche a pied de loisir – LIFE+ Peche a pied de loisir . Ce rapport presente : · le protocole de suivi de terrain des recifs d’hermelles incluant les procedures de travail et strategie d'echantillonnage de terrain (fiches protocoles - detaillee et condensee - et fiches de saisie de donnees), les parametres de suivi des recifs d’hermelles, les methodes de traitements et de calcul des indicateurs ; · l'evolution des etats ecologiques des recifs d’hermelles sur les deux sites de la Baie du Mont-Saint- Michel (Sainte-Anne et Champeaux-Fregate) en tenant compte d’...

This progress report summarizes actual advancements (February 2007) in order to propose a monitor... more This progress report summarizes actual advancements (February 2007) in order to propose a monitoring benthic network according to the European Water Framework Directive for the area concerned by the Seine-Normandie water district Mots-clés Directive Cadre Eau, Benthos, Réseau de surveillance, Manche Words keys European Water Framework Directive, Benthos, Monitoring Network, the Channel

In the eastern Bay of Seine, which is a representative area of coastal zones exposed to numerous ... more In the eastern Bay of Seine, which is a representative area of coastal zones exposed to numerous anthropogenic disturbances, data from a long-term monitoring program of the benthic macrofauna based on a framework of 60 stations sampled during 7 cruises from 1988 to 2016 were used to investigate the link between species and functional diversity at different scales and assess how long-term changes in the community structure may have altered the ecosystem functioning. To cover the different facets of α-diversity, a selection of species and functional diversity indices were calculated and the links between these metrics were determined from a Principal Component Analysis. The β-diversity was analysed by applying multivariate methods on both species and traits composition matrices. Population fluctuations of a few very abundant species led to the major variations observed in the structure of the community in both taxonomic and functional aspects. A certain redundancy was found among spec...

ICES Journal of Marine Science

Species ranges are shifting globally to track temperature changes in response to climate warming,... more Species ranges are shifting globally to track temperature changes in response to climate warming, with substantial variability among taxa. In the English Channel, a biogeographical transition zone between the cold temperate and warm temperate provinces of the North-East Atlantic, distribution shifts have been relatively well documented for plankton, fish and intertidal benthic organisms, but little information is available on sublittoral benthos. Following a description of the magnitude of the sea bottom temperature (SBT) rise, the changes in the distribution and occupancy of 65 benthic invertebrate species were analysed by comparing data collected throughout the English Channel at more than 200 stations sampled during a cool period in the 1960s–1970s and at present in 2012–2014. A non-uniform rise in SBT for the last three decades was observed at the regional scale, varying from 0.07 to 0.54°C per decade. This rise differs from that reported for sea surface temperature (SST) in str...

Ecological Modelling

In order to better understand and predict the dynamics of benthic macroinvertebrate communities, ... more In order to better understand and predict the dynamics of benthic macroinvertebrate communities, we need to first define the functional components of benthic biodiversity and then provide a mechanistic description of how they interact with their abiotic environment, their basic resources and each other. These interactions should be largely controlled by readily available biological traits, making trait-based modelling an ideal framework for the synthesis of relevant hypotheses from ecological theory and expert knowledge. With the help of benthic species traits, we derived a set of first principles regarding the role of organisms in processes of environmental filtering, consumption of algae/detritus, predation, use of space, biogenic habitat modification and trade-offs in the utilization and allocation of resources. These principles were incorporated into qualitative models in the form of functional relationships linking groups of benthic organisms in the Rance estuary (Brittany, France). The general stability of these models illustrates their potential to persist in time and to constitute a plausible representation of the natural world. Their structure provides insight into the role of various community assembly mechanisms and the direction that the system might take in response to perturbations. The results are expected to inform the development of quantitative models reproducing the spatial and temporal dynamics of marine benthic biodiversity in the Rance estuary. Highlights ► We derived first principles on the role of benthic organisms in community assembly. ► These principles dictated functional relationships among groups of benthic species. ► Groups and functional relationships comprised qualitative models of benthic systems. ► Stability analysis supported the models' potential to represent benthic communities. ► Model structure offered insight into the role of some community assembly mechanisms.

Estuarine, Coastal and Shelf Science, 2016

The relationship between foraging shorebirds, macrobenthos and sedimentary parameters has been wi... more The relationship between foraging shorebirds, macrobenthos and sedimentary parameters has been widely studied across Western Europe. Megatidal areas have large zones uncovered when the water retreats. Consequently, in such cases, the tide also influences foraging activities. This paper examines the use of an intertidal space by waders to define how macrobenthic resource concentrates foraging activity of birds in a large megatidal sandflat. This approach combines accurate spatial distribution of waders (Oystercatcher, Eurasian curlew, Bar-tailed Godwit and Redknot) according to their activity with ecological/biological parameters. A differential exploitation of the flat is clearly shown, with macrobenthic biomass appearing as one of the main explanatory factor for the four species considered on the western part of the bay and altitude (shore elevation) in the eastern part. The novelty of this study relates to the large area, also presumed to be a functional unit, while considering at the same time the singularities of the different parts of the flat. This multi-scale approach identifies important factors influencing the differential distribution patterns observed. The different selected parameters present an important variability in their contribution, underlining the complexity of explaining the distribution of foraging birds. Consequently, the study of such complex phenomena needs to consider additional variables to improve the relevance of explanatory models. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Ce rapport présente les résultats des opérations menées en 2008 (contrôle de surveillance du comp... more Ce rapport présente les résultats des opérations menées en 2008 (contrôle de surveillance du compartiment benthique : macroinvertébrés benthiques et macroalgues), sur l'ensemble des masses d'eau côtières et de transitions rattachées au district Artois-Picardie.

Journal of Sea Research, 2004

Growth, condition, diet and spatial distribution of the solenette Buglossidium luteum (Risso, 181... more Growth, condition, diet and spatial distribution of the solenette Buglossidium luteum (Risso, 1810) were investigated along the coasts of the French Atlantic, eastern English Channel and Southern Bight of the North Sea. Distribution and habitat preferences of solenette were analysed in relation to physical and biological features presumed to influence fish distribution. B. luteum was patchily distributed and concentrated in shallow muddy and muddy-sand bottoms moderately influenced by estuarine waters (euhaline waters). In the studied area, solenette seemed to find habitats suitable for growth. Food availability was not assumed to be a limiting factor for solenette distribution in contrast to abiotic factors such as salinity.

Journal of Sea Research, 2004

Growth, condition, diet and spatial distribution of the solenette Buglossidium luteum (Risso, 181... more Growth, condition, diet and spatial distribution of the solenette Buglossidium luteum (Risso, 1810) were investigated along the coasts of the French Atlantic, eastern English Channel and Southern Bight of the North Sea. Distribution and habitat preferences of solenette were analysed in relation to physical and biological features presumed to influence fish distribution. B. luteum was patchily distributed and concentrated in shallow muddy and muddy-sand bottoms moderately influenced by estuarine waters (euhaline waters). In the studied area, solenette seemed to find habitats suitable for growth. Food availability was not assumed to be a limiting factor for solenette distribution in contrast to abiotic factors such as salinity.

Estuarine, Coastal and …, 2011

Coastal bays provide habitats for juveniles and adults of many marine species. Mont Saint-Michel ... more Coastal bays provide habitats for juveniles and adults of many marine species. Mont Saint-Michel Bay (MSMB, France) hosts a highly diversified fish community and constitutes one of the most important nursery grounds for many commercially exploited marine species, such as sea ...

Marine Environmental Research

ICES Journal of Marine Science

Although colonization of artificial structures by epibenthic communities is well-documented overa... more Although colonization of artificial structures by epibenthic communities is well-documented overall, our understanding of colonization processes is largely limited to low-energy environments. In this study, we monitored epibenthic colonization of different structures associated with a tidal energy test site located in a high-energy hydrodynamic environment. Using four years of image-based underwater surveys, we characterized changes through space and time in the taxonomic composition of epibenthic assemblages colonizing two kinds of artificial structures, as well as the surrounding natural habitat. Our results highlight that ecological successions followed similar trends across the two artificial habitats, but that different habitat-specific communities emerged at the end of our survey. Deployment of these artificial structures resulted in the addition of elevated and stable substrata in an environment where natural hard substrates are unstable and strongly exposed to sediment abras...