Journal of Experimental Marine Biology and Ecology, Jan 15, 2003
Tube-dwelling polychaetes provide habitat structures that potentially affect the composition of t... more Tube-dwelling polychaetes provide habitat structures that potentially affect the composition of the benthic community. This study describes the long-term effects of tubes as a physical structure on the fauna of an intertidal sandflat, based on a field experiment with tubes that mimicked those of the terebellid polychaete Lanice conchilega.
Juveniles of the tube-dwelling polychaete L. conchilega were found attached to adult tubes at an ... more Juveniles of the tube-dwelling polychaete L. conchilega were found attached to adult tubes at an exposed beach in South Wales (U.K.). They attached to the upper part of tubes protruding above the sediment. The aim of this study was to determine the timing of juvenile settlement on to adult tubes, their abundance and size distribution, and the time of detachment and densities in the sediment after re-settlement. Furthermore, to establish whether the sediment composition of juvenile tubes differed from those of adults and the surrounding sediment. and 2000, tubes of adult L. conchilega were sampled and numbers of attached juveniles were quantified and their sizes measured. Densities of solitary L. conchilega in the sediment were estimated, as well as the size distribution of solitary tubes. On average, 5-13 juveniles were attached to single adult tubes in spring, but numbers varied greatly with up to 72 juveniles on a single tube in April 1998. Availability of a hard substratum and chemical cues are discussed as potential factors triggering the attachment of juveniles to adult tubes. Juveniles started to detach and re-settle in the sediment 1 month after attachment. Once settled in the sediment, juvenile numbers decreased steeply, but the size distribution of solitary L. conchilega suggested that some juveniles survived in the population. However, the extent to which numbers of juvenile recruits contribute to the density of adults remained unclear. Juveniles used a smaller mean particle size for tube building than adults, but both actively selected particles.
Journal of Experimental Marine Biology and Ecology, 2003
Tube-dwelling polychaetes provide habitat structures that potentially affect the composition of t... more Tube-dwelling polychaetes provide habitat structures that potentially affect the composition of the benthic community. This study describes the long-term effects of tubes as a physical structure on the fauna of an intertidal sandflat, based on a field experiment with tubes that mimicked those of the terebellid polychaete Lanice conchilega.
Juveniles of the tube-dwelling polychaete L. conchilega were found attached to adult tubes at an ... more Juveniles of the tube-dwelling polychaete L. conchilega were found attached to adult tubes at an exposed beach in South Wales (U.K.). They attached to the upper part of tubes protruding above the sediment. The aim of this study was to determine the timing of juvenile settlement on to adult tubes, their abundance and size distribution, and the time of detachment and densities in the sediment after re-settlement. Furthermore, to establish whether the sediment composition of juvenile tubes differed from those of adults and the surrounding sediment. and 2000, tubes of adult L. conchilega were sampled and numbers of attached juveniles were quantified and their sizes measured. Densities of solitary L. conchilega in the sediment were estimated, as well as the size distribution of solitary tubes. On average, 5-13 juveniles were attached to single adult tubes in spring, but numbers varied greatly with up to 72 juveniles on a single tube in April 1998. Availability of a hard substratum and chemical cues are discussed as potential factors triggering the attachment of juveniles to adult tubes. Juveniles started to detach and re-settle in the sediment 1 month after attachment. Once settled in the sediment, juvenile numbers decreased steeply, but the size distribution of solitary L. conchilega suggested that some juveniles survived in the population. However, the extent to which numbers of juvenile recruits contribute to the density of adults remained unclear. Juveniles used a smaller mean particle size for tube building than adults, but both actively selected particles.
Size-based analyses of marine animals are increasingly used to improve understanding of community... more Size-based analyses of marine animals are increasingly used to improve understanding of community structure and function. However, the resources required to record individual body weights for benthic animals, where the number of individuals can reach several thousand in a square metre, are often prohibitive. Here we present morphometric (length -weight) relationships for 216 benthic species from the North Sea to permit weight estimation from length measurements. These relationships were calculated using data collected over two years from 283 stations. For ten abundant and widely dispersed species we tested for significant spatial and temporal differences in morphometric relationships. Some were found, but the magnitude of differences was small in relation to the size-ranges of animals that are usually present and we recommend that the regression relationships given here, based on pooled data, are appropriate for most types of population and community analyses. Our hope is that the availability of these morphometric relationships will encourage the more frequent application of size-based analyses to benthic survey data, and so enhance understanding of the ecology of the benthic/demersal component of marine ecosystems and food webs. Modelling an exploited marine fish community with 15 parametersresults from a simple size-based model.
Synopsis Dense aggregations of tube-worms can stabilize sediments and generate oases for benthic ... more Synopsis Dense aggregations of tube-worms can stabilize sediments and generate oases for benthic communities that are different and often more diverse and abundant than those of the surroundings. If these features are to qualify as biogenic reefs under nature-conservation legislation such as the EC Habitats Directive, a level of stability and longevity is desirable aside from physical and biological attributes. Lanice conchilega (Pallas, 1766) is widely distributed around the European coast and aggregations of this tube-dwelling polychaete are known to have a positive effect on the biodiversity of associated species in inter-and sub-tidal areas. This increases the value of L. conchilega-rich habitats for higher trophic levels such as birds and fish. However, L. conchilega is currently not recognized as a reef builder primarily due to uncertainty about the stability of their aggregations. We carried out three studies on different spatial and temporal scales to explore a number of properties relating to stability: (1) Individual aggregations of L. conchilega of $1 m 2 were monitored for up to 1 year, (2) records of L. conchilega from a 258-ha area over a 35-year period were analyzed, (3) the recovery of a population of L. conchilega subjected to disturbances by cultivation of Manila clams (Ruditapes philippinarum) was followed over 3 years. The studies provided evidence about the longevity of L. conchilega aggregations, their resistance to disturbance, their resilience in recovering from negative impact and their large-scale persistence. The results showed that populations of L. conchilega were prone to considerable fluctuation and the stability of aggregations depended on environmental factors and on recruitment. The tube-worms proved to be susceptible to disturbance by cultivation of Manila clams but demonstrated the potential to recover from that impact. The long-term monitoring of a large L. conchilega population in the Bay of Mont Saint Michel (France) indicated that aggregations can persist over many decades with a constant, densely populated core area and an expanding and contracting more thinly populated fringe zone. The stability of aggregations of L. conchilega and the structures they form do not unequivocally fit the currently accepted definition of a reef. However, given L. conchilega's accepted reef-like potential to influence diversity and abundance in benthic communities, we suggest clarifying and expanding the definition of reefs so that species with records of significant persistence in particular areas and which otherwise meet expectations of reefs are included within the definition.
Theoretical models linking species diversity to disturbance consider disturbance to be the altera... more Theoretical models linking species diversity to disturbance consider disturbance to be the alteration of population mortality rates caused by the specified perturbation. Current knowledge of the ecological disturbance caused by fishing to marine fish and benthic invertebrate communities is reviewed. This review considers the various components of mortality caused by fishing (eg landings, discards, trawl escapees, etc) and examines the information currently available, or required, to determine the importance of each component in assessing the mortality of fish and benthos caused by fishing.
In order for management to be proactive, it is necessary to predict the ecological consequences o... more In order for management to be proactive, it is necessary to predict the ecological consequences of specific management actions. To date fisheries management has involved catch limitation through the setting of Total Allowable Catches (TACs) for each coming year. However, the ecological consequences of fishing are generally modelled on the basis of variation in fishing effort. To predict the ecological consequences associated with particular sets of TACs therefore requires that the patterns of fishing activity necessary to achieve these TACs be estimated. This requires knowledge of the relationship between landings and fishing effort.
... Authors' addresses: RUTH Z ALEX FORD, JOHN LANCASTER, University of Wal... more ... Authors' addresses: RUTH Z ALEX FORD, JOHN LANCASTER, University of Wales Swansea, Biological Sciences, Singleton Park, Swansea, SA2 8PP, UK, e-mail: [email protected]. uk - JOHN COTTER, SIMON JENNINGS, CEFAS, Lowestoft ... (1989) and DYER et al. ...
Journal of Experimental Marine Biology and Ecology, Jan 15, 2003
Tube-dwelling polychaetes provide habitat structures that potentially affect the composition of t... more Tube-dwelling polychaetes provide habitat structures that potentially affect the composition of the benthic community. This study describes the long-term effects of tubes as a physical structure on the fauna of an intertidal sandflat, based on a field experiment with tubes that mimicked those of the terebellid polychaete Lanice conchilega.
Juveniles of the tube-dwelling polychaete L. conchilega were found attached to adult tubes at an ... more Juveniles of the tube-dwelling polychaete L. conchilega were found attached to adult tubes at an exposed beach in South Wales (U.K.). They attached to the upper part of tubes protruding above the sediment. The aim of this study was to determine the timing of juvenile settlement on to adult tubes, their abundance and size distribution, and the time of detachment and densities in the sediment after re-settlement. Furthermore, to establish whether the sediment composition of juvenile tubes differed from those of adults and the surrounding sediment. and 2000, tubes of adult L. conchilega were sampled and numbers of attached juveniles were quantified and their sizes measured. Densities of solitary L. conchilega in the sediment were estimated, as well as the size distribution of solitary tubes. On average, 5-13 juveniles were attached to single adult tubes in spring, but numbers varied greatly with up to 72 juveniles on a single tube in April 1998. Availability of a hard substratum and chemical cues are discussed as potential factors triggering the attachment of juveniles to adult tubes. Juveniles started to detach and re-settle in the sediment 1 month after attachment. Once settled in the sediment, juvenile numbers decreased steeply, but the size distribution of solitary L. conchilega suggested that some juveniles survived in the population. However, the extent to which numbers of juvenile recruits contribute to the density of adults remained unclear. Juveniles used a smaller mean particle size for tube building than adults, but both actively selected particles.
Journal of Experimental Marine Biology and Ecology, 2003
Tube-dwelling polychaetes provide habitat structures that potentially affect the composition of t... more Tube-dwelling polychaetes provide habitat structures that potentially affect the composition of the benthic community. This study describes the long-term effects of tubes as a physical structure on the fauna of an intertidal sandflat, based on a field experiment with tubes that mimicked those of the terebellid polychaete Lanice conchilega.
Juveniles of the tube-dwelling polychaete L. conchilega were found attached to adult tubes at an ... more Juveniles of the tube-dwelling polychaete L. conchilega were found attached to adult tubes at an exposed beach in South Wales (U.K.). They attached to the upper part of tubes protruding above the sediment. The aim of this study was to determine the timing of juvenile settlement on to adult tubes, their abundance and size distribution, and the time of detachment and densities in the sediment after re-settlement. Furthermore, to establish whether the sediment composition of juvenile tubes differed from those of adults and the surrounding sediment. and 2000, tubes of adult L. conchilega were sampled and numbers of attached juveniles were quantified and their sizes measured. Densities of solitary L. conchilega in the sediment were estimated, as well as the size distribution of solitary tubes. On average, 5-13 juveniles were attached to single adult tubes in spring, but numbers varied greatly with up to 72 juveniles on a single tube in April 1998. Availability of a hard substratum and chemical cues are discussed as potential factors triggering the attachment of juveniles to adult tubes. Juveniles started to detach and re-settle in the sediment 1 month after attachment. Once settled in the sediment, juvenile numbers decreased steeply, but the size distribution of solitary L. conchilega suggested that some juveniles survived in the population. However, the extent to which numbers of juvenile recruits contribute to the density of adults remained unclear. Juveniles used a smaller mean particle size for tube building than adults, but both actively selected particles.
Size-based analyses of marine animals are increasingly used to improve understanding of community... more Size-based analyses of marine animals are increasingly used to improve understanding of community structure and function. However, the resources required to record individual body weights for benthic animals, where the number of individuals can reach several thousand in a square metre, are often prohibitive. Here we present morphometric (length -weight) relationships for 216 benthic species from the North Sea to permit weight estimation from length measurements. These relationships were calculated using data collected over two years from 283 stations. For ten abundant and widely dispersed species we tested for significant spatial and temporal differences in morphometric relationships. Some were found, but the magnitude of differences was small in relation to the size-ranges of animals that are usually present and we recommend that the regression relationships given here, based on pooled data, are appropriate for most types of population and community analyses. Our hope is that the availability of these morphometric relationships will encourage the more frequent application of size-based analyses to benthic survey data, and so enhance understanding of the ecology of the benthic/demersal component of marine ecosystems and food webs. Modelling an exploited marine fish community with 15 parametersresults from a simple size-based model.
Synopsis Dense aggregations of tube-worms can stabilize sediments and generate oases for benthic ... more Synopsis Dense aggregations of tube-worms can stabilize sediments and generate oases for benthic communities that are different and often more diverse and abundant than those of the surroundings. If these features are to qualify as biogenic reefs under nature-conservation legislation such as the EC Habitats Directive, a level of stability and longevity is desirable aside from physical and biological attributes. Lanice conchilega (Pallas, 1766) is widely distributed around the European coast and aggregations of this tube-dwelling polychaete are known to have a positive effect on the biodiversity of associated species in inter-and sub-tidal areas. This increases the value of L. conchilega-rich habitats for higher trophic levels such as birds and fish. However, L. conchilega is currently not recognized as a reef builder primarily due to uncertainty about the stability of their aggregations. We carried out three studies on different spatial and temporal scales to explore a number of properties relating to stability: (1) Individual aggregations of L. conchilega of $1 m 2 were monitored for up to 1 year, (2) records of L. conchilega from a 258-ha area over a 35-year period were analyzed, (3) the recovery of a population of L. conchilega subjected to disturbances by cultivation of Manila clams (Ruditapes philippinarum) was followed over 3 years. The studies provided evidence about the longevity of L. conchilega aggregations, their resistance to disturbance, their resilience in recovering from negative impact and their large-scale persistence. The results showed that populations of L. conchilega were prone to considerable fluctuation and the stability of aggregations depended on environmental factors and on recruitment. The tube-worms proved to be susceptible to disturbance by cultivation of Manila clams but demonstrated the potential to recover from that impact. The long-term monitoring of a large L. conchilega population in the Bay of Mont Saint Michel (France) indicated that aggregations can persist over many decades with a constant, densely populated core area and an expanding and contracting more thinly populated fringe zone. The stability of aggregations of L. conchilega and the structures they form do not unequivocally fit the currently accepted definition of a reef. However, given L. conchilega's accepted reef-like potential to influence diversity and abundance in benthic communities, we suggest clarifying and expanding the definition of reefs so that species with records of significant persistence in particular areas and which otherwise meet expectations of reefs are included within the definition.
Theoretical models linking species diversity to disturbance consider disturbance to be the altera... more Theoretical models linking species diversity to disturbance consider disturbance to be the alteration of population mortality rates caused by the specified perturbation. Current knowledge of the ecological disturbance caused by fishing to marine fish and benthic invertebrate communities is reviewed. This review considers the various components of mortality caused by fishing (eg landings, discards, trawl escapees, etc) and examines the information currently available, or required, to determine the importance of each component in assessing the mortality of fish and benthos caused by fishing.
In order for management to be proactive, it is necessary to predict the ecological consequences o... more In order for management to be proactive, it is necessary to predict the ecological consequences of specific management actions. To date fisheries management has involved catch limitation through the setting of Total Allowable Catches (TACs) for each coming year. However, the ecological consequences of fishing are generally modelled on the basis of variation in fishing effort. To predict the ecological consequences associated with particular sets of TACs therefore requires that the patterns of fishing activity necessary to achieve these TACs be estimated. This requires knowledge of the relationship between landings and fishing effort.
... Authors' addresses: RUTH Z ALEX FORD, JOHN LANCASTER, University of Wal... more ... Authors' addresses: RUTH Z ALEX FORD, JOHN LANCASTER, University of Wales Swansea, Biological Sciences, Singleton Park, Swansea, SA2 8PP, UK, e-mail: [email protected]. uk - JOHN COTTER, SIMON JENNINGS, CEFAS, Lowestoft ... (1989) and DYER et al. ...
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