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Over the last few years significant advances have been made in our knowledge of the environmental impacts of marine aggregate extraction. We now have a good understanding of the effect that dredging has on benthic communities within actively dredged areas. Our understanding of the recoverability of these communities is also advancing and whilst recovery to en exact replica of the pre-dredge community is unlikely, a similar community could be expected to have established itself within a number of years following the cessation of dredging activities. The structure of the benthic community which colonises a previously impacted area will be determined largely by the larvae that are available in the water column, as well as by species inhabiting neighbouring areas that are capable of colonisation through direct migration. In order to properly manage these marine resources it is important to understand the implications of the direct impacts of aggregate dredging on the benthos as well as the subsequent stages in marine food web recovery. Very little is known of the role played by benthic taxa that characterise marine sands and gravels in supporting marine food webs. Information exists on the diet of only a limited number of fish species, mostly of commercial interest and rarely linked directly to benthic resources. An ecosystem approach has been employed here to investigate the ways in which marine fish are utilising benthic resources as food. The stomach contents of over 500 fish sampled with a 1m Beam trawl at aggregate extraction sites around the UK have been analysed. These were collected as part of two previous research projects funded through the ALSF (MEPF 04/02 & MAL0027) as well as through an environmental impact assessment carried out at Hastings Shingle Bank. These data were analysed in order to establish the diets of each of the 18 fish species studied in relation to the availability of prey. Diets were also compared between fish sampled in different environments in order to establish other sources of variation in their feeding behaviour. A strong link was established between the diets of individual fish and the available benthic prey. The diet of most of the fish species studied also showed a high degree of trophic adaptability, with a variety of prey items being utilised. Despite the variety evident in the prey consumption, crustacea were by far the most common prey type consumed. This result may have been exaggerated by the slow rate of digestion of this group compared to smaller soft bodied invertebrates. Nevertheless, with crustacea commonly accounting for 50% or more of the stomach contents, this group is clearly an important component of the benthos in terms of supporting higher trophic levels. In contrast to the dietary trends observed here, where crustacea are the dominant component, the benthos is typically dominated by polychaete worms, with crustacea being present only in quite small proportions. Crustacea, also tend to be larger in size and longer lived than polychaete worms meaning that they may take longer to recover. Therefore, whilst the opportunistic feeding behaviour observed in the majority of the fish indicates that they would cope well with alterations to the benthos the preference observed for crustacea may mean that this component of the benthos would need to recover before fish would use the area to feed. The role of the Annex I habitat Sabellaria spinulosa reef in supporting higher trophic levels was also investigated by comparing fish sampled in areas where reefs had been identified with those found in areas where reefs had not been identified. A significant alteration in the diet was observed in fish associated with S.spinulosa reefs which appears to be due to a slightly elevated level of feeding and an increased preference for the porcelain crab Pisidia. Pisidia has been shown to be associated with S.spinulosa reefs in very high abundances and it is therefore not surprising that it is targeted as a source of food in these areas. Whilst this study has advanced our understanding of the link between benthic communities and higher trophic levels, the number of observations was relatively small. Seasonal variability of fish diets is known to be high and this is something which has not been dealt with at all in this study as all fish were sampled during the summer months. It is possible that not only the diet, but also the feeding behaviour and trophic adaptability of fish may vary with the seasons and for this reason the results observed here should be treated with some caution. This study was also limited to smaller demersal fish which are easily caught with a scientific beam trawl; in order to understand the implications of aggregate extraction on the marine food web as a whole this would need to be extended to include larger pelagic fish species.
The Crown Estate
| Other details | ||
| Internal code | Internally assigned metadata identifier | 6799 |
| Title | The title is used to provide a brief and precise description of the dataset such as 'Date', 'Originating organisation/programme', 'Location' and 'Type of survey'. All acronyms and abbreviations should be reproduced in full. | 2007, Marine Ecological Surveys Limited, Predictive Framework for Assessment of Recoverability of Marine Benthic Communities Following Cessation of Aggregate Dredging |
| Alternative title | The purpose of alternative title is to record any additional names by which the dataset may be known. | MEPF 04/02 Extension |
| File Identifier | The File Identifier is a code, preferably a GUID, that is globally unique and remains with the same metadata record even if the record is edited or transferred between portals or tools. | 375a286e46cb5a28b5ccfeb2334f4a64 |
| Resource Identifier | This is the code assigned by the data owner. | 20379 |
| Resource type | The resource type will likely be a dataset but could also be a series (collection of datasets with a common specification) or a service. | series |
| Start date | This describes the date the resource starts. This may only be the year if month and day are not known | 2007-03-30 |
| End date | This describes the date the resource ends. This may only be the year if month and day are not known | 2007-10-04 |
| Spatial resolution | This describes the spatial resolution of the dataset or the spatial limitations of the service. | 1 |
| Spatial resolution unit | This describes the unit of spatial resolution which for distance must be metres. | http://standards.iso.org/ittf/PubliclyAvailableStandards/ISO_19139_Schemas/resources/uom/gmxUom.xml#m |
| Frequency of updates | This describes the frequency with which the resource is modified or updated i.e. a monitoring programme that samples once per year has a frequency that is described as 'annually'. | notPlanned |
| Abstract | The abstract provides a clear and brief statement of the content of the resource. | Over the last few years significant advances have been made in our knowledge of the environmental impacts of marine aggregate extraction. We now have a good understanding of the effect that dredging has on benthic communities within actively dredged areas. Our understanding of the recoverability of these communities is also advancing and whilst recovery to en exact replica of the pre-dredge community is unlikely, a similar community could be expected to have established itself within a number of years following the cessation of dredging activities. The structure of the benthic community which colonises a previously impacted area will be determined largely by the larvae that are available in the water column, as well as by species inhabiting neighbouring areas that are capable of colonisation through direct migration. In order to properly manage these marine resources it is important to understand the implications of the direct impacts of aggregate dredging on the benthos as well as the subsequent stages in marine food web recovery. Very little is known of the role played by benthic taxa that characterise marine sands and gravels in supporting marine food webs. Information exists on the diet of only a limited number of fish species, mostly of commercial interest and rarely linked directly to benthic resources. An ecosystem approach has been employed here to investigate the ways in which marine fish are utilising benthic resources as food. The stomach contents of over 500 fish sampled with a 1m Beam trawl at aggregate extraction sites around the UK have been analysed. These were collected as part of two previous research projects funded through the ALSF (MEPF 04/02 & MAL0027) as well as through an environmental impact assessment carried out at Hastings Shingle Bank. These data were analysed in order to establish the diets of each of the 18 fish species studied in relation to the availability of prey. Diets were also compared between fish sampled in different environments in order to establish other sources of variation in their feeding behaviour. A strong link was established between the diets of individual fish and the available benthic prey. The diet of most of the fish species studied also showed a high degree of trophic adaptability, with a variety of prey items being utilised. Despite the variety evident in the prey consumption, crustacea were by far the most common prey type consumed. This result may have been exaggerated by the slow rate of digestion of this group compared to smaller soft bodied invertebrates. Nevertheless, with crustacea commonly accounting for 50% or more of the stomach contents, this group is clearly an important component of the benthos in terms of supporting higher trophic levels. In contrast to the dietary trends observed here, where crustacea are the dominant component, the benthos is typically dominated by polychaete worms, with crustacea being present only in quite small proportions. Crustacea, also tend to be larger in size and longer lived than polychaete worms meaning that they may take longer to recover. Therefore, whilst the opportunistic feeding behaviour observed in the majority of the fish indicates that they would cope well with alterations to the benthos the preference observed for crustacea may mean that this component of the benthos would need to recover before fish would use the area to feed. The role of the Annex I habitat Sabellaria spinulosa reef in supporting higher trophic levels was also investigated by comparing fish sampled in areas where reefs had been identified with those found in areas where reefs had not been identified. A significant alteration in the diet was observed in fish associated with S.spinulosa reefs which appears to be due to a slightly elevated level of feeding and an increased preference for the porcelain crab Pisidia. Pisidia has been shown to be associated with S.spinulosa reefs in very high abundances and it is therefore not surprising that it is targeted as a source of food in these areas. Whilst this study has advanced our understanding of the link between benthic communities and higher trophic levels, the number of observations was relatively small. Seasonal variability of fish diets is known to be high and this is something which has not been dealt with at all in this study as all fish were sampled during the summer months. It is possible that not only the diet, but also the feeding behaviour and trophic adaptability of fish may vary with the seasons and for this reason the results observed here should be treated with some caution. This study was also limited to smaller demersal fish which are easily caught with a scientific beam trawl; in order to understand the implications of aggregate extraction on the marine food web as a whole this would need to be extended to include larger pelagic fish species. |
| Lineage | Lineage includes the background information, history of the sources of data, data quality statements and methods. | Funded by Defra under ALSF. |
| Additional information | This describes relevant references to the data e.g. reports, articles, websites plus other useful information not captured elsewhere. | Presentation type: digital representation of a primarily textual item (can contain illustrations also) Spatial representation type: 001 Supply media: 001 Origin: Marine Ecological Surveys Ltd. |
| Related keywords | ||
| Keyword | General subject area(s) associated with the resource, uses multiple controlled vocabularies | Research |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Research and Development Activity | |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Biota abundance, biomass and diversity | |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Sedimentary structure | |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Sediment grain size parameters | |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Biodiversity indices | |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Depositional environment | |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Marine Environmental Data and Information Network | |
| Keyword title | MEDIN | |
| Keyword | General subject area(s) associated with the resource, uses multiple controlled vocabularies | Marine Environmental Data and Information Network |
| Keyword title | MEDIN | |
| Geographical coverage | ||
| North | The northern-most limit of the data resource in decimal degrees | 49.7672631874 |
| East | The eastern-most limit of the data resource in decimal degrees | -7.55719702927 |
| South | The southern-most limit of the data resource in decimal degrees | 49.7672598192 |
| West | The western-most limit of the data resource in decimal degrees | -7.5572338114 |
| Responsible organisations | ||
| Role | The point of contact is person or organisation with responsibility for the creation and maintenance of the metadata for the resource. | pointOfContact |
| Organisation name | Department for Environment Food and Rural Affairs | |
| Phone | +44(0)2072386609 | |
| Delivery point | Information Resource Centre, Lower Ground floor, Ergon House | |
| URL | http://www.defra.gov.uk | |
| Role | The custodian is the person or organisation that accepts responsibility for the resource and ensures appropriate care and maintenance. If a dataset has been lodged with a Data Archive Centre for maintenance then this organisation is be entered here. | custodian |
| Organisation name | The Crown Estate | |
| Phone | +44 020 7851 5000 | |
| Delivery point | 16 New Burlington Place | |
| Postal code | W1S 2HX | |
| City | London | |
| Country | United Kingdom | |
| URL | http://www.thecrownestate.co.uk | |
| Role | The originator is the person or organisation who created, collected or produced the resource. | originator |
| Organisation name | Marine Ecological Surveys Ltd | |
| Phone | +44 (0)1225 442211 | |
| Fax | +44 (0)1225 444411 | |
| Delivery point | 3 Palace Yard Mews | |
| Postal code | BA1 2NH | |
| City | Bath | |
| Country | United Kingdom | |
| URL | http://www.seasurvey.co.uk/ | |
| Resource locators | ||
| Legal limitations | Any restrictions imposed on accessing the resource. | no conditions apply |
| Available data formats | ||
| Data format name | Format in which digital data can be provided for transfer | Government Funded |
| Version info | ||
| Date of publication | The publication date of the resource or if previously unpublished the date that the resource was made publicly available via the MEDIN network. | 2008-03-31 |
| Date of creation | The date that the resource was created. | 2007-01-01 |
| Metadata date | The date when the content of this metadata record was last updated. | 2008-03-18 |
| Metadata standard name | The name of the metadata standard used to create this metadata | MEDIN Discovery Metadata Standard |
| Metadata standard version | The version of the MEDIN Discovery Metadata Standard used to create the metadata record | Version 2.3.5 |
© OpenStreetMap contributors