36 research outputs found
Assessing the sensitivity of subtidal sedimentary habitats to pressures associated with marine activities. Phase 1 Report: Rationale and proposed ecological groupings for Level 5 biotopes against which sensitivity assessments would be best undertaken.
The purpose of this study is to produce a series of Conceptual Ecological Models (CEMs)
that represent sublittoral rock habitats in the UK. CEMs are diagrammatic representations of
the influences and processes that occur within an ecosystem. They can be used to identify
critical aspects of an ecosystem that may be studied further, or serve as the basis for the
selection of indicators for environmental monitoring purposes. The models produced by this
project are control diagrams, representing the unimpacted state of the environment free from
anthropogenic pressures.
It is intended that the models produced by this project will be used to guide indicator
selection for the monitoring of this habitat in UK waters. CEMs may eventually be produced
for a range of habitat types defined under the UK Marine Biodiversity Monitoring R&D
Programme (UKMBMP), which, along with stressor models, are designed to show the
interactions within impacted habitats, would form the basis of a robust method for indicator
selection. This project builds on the work to develop CEMs for shallow sublittoral coarse
sediment habitats (Alexander et al 2014).
The project scope included those habitats defined as ‘sublittoral rock’. This definition
includes those habitats that fall into the EUNIS Level 3 classifications A3.1 Atlantic and
Mediterranean high energy infralittoral rock, A3.2 Atlantic and Mediterranean moderate
energy infralittoral rock, A3.3 Atlantic and Mediterranean low energy infralittoral rock, A4.1
Atlantic and Mediterranean high energy circalittoral rock, A4.2 Atlantic and Mediterranean
moderate energy circalittoral rock, and A4.3 Atlantic and Mediterranean low energy
circalittoral rock as well as the constituent Level 4 and 5 biotopes that are relevant to UK
waters. A species list of characterising fauna to be included within the scope of the models
was identified using an iterative process to refine the full list of species found within the
relevant Level 5 biotopes.
A literature review was conducted using a pragmatic and iterative approach to gather
evidence regarding species traits and information that would be used to inform the models
and characterise the interactions that occur within the sublittoral rock habitat. All information
gathered during the literature review was entered into a data logging pro-forma spreadsheet
that accompanies this report. Wherever possible, attempts were made to collect information
from UK-specific peer-reviewed studies, although other sources were used where
necessary. All data gathered was subject to a detailed confidence assessment. Expert
judgement by the project team was utilised to provide information for aspects of the models
for which references could not be sourced within the project timeframe.
A multivariate analysis approach was adopted to assess ecologically similar groups (based
on ecological and life history traits) of fauna from the identified species to form the basis of
the models. A model hierarchy was developed based on these ecological groups. One
general control model was produced that indicated the high-level drivers, inputs, biological
assemblages, ecosystem processes and outputs that occur in sublittoral rock habitats. In
addition to this, seven detailed sub-models were produced, which each focussed on a
particular ecological group of fauna within the habitat: ‘macroalgae’, ‘temporarily or
permanently attached active filter feeders’, ‘temporarily or permanently attached passive
filter feeders’, ‘bivalves, brachiopods and other encrusting filter feeders’, ‘tube building
fauna’, ‘scavengers and predatory fauna’, and ‘non-predatory mobile fauna’. Each sub-model
is accompanied by an associated confidence model that presents confidence in the links
between each model component. The models are split into seven levels and take spatial and
temporal scale into account through their design, as well as magnitude and direction of
influence. The seven levels include regional to global drivers, water column processes, local
inputs/processes at the seabed, habitat and biological assemblage, output processes, local
ecosystem functions, and regional to global ecosystem functions.
The models indicate that whilst the high level drivers that affect each ecological group are
largely similar, the output processes performed by the biota and the resulting ecosystem
functions vary both in number and importance between groups. Confidence within the
models as a whole is generally high, reflecting the level of information gathered during the
literature review.
Physical drivers which influence the ecosystem were found to be of high importance for the
sublittoral rock habitat, with factors such as wave exposure, water depth and water currents
noted to be crucial in defining the biological assemblages. Other important factors such as
recruitment/propagule supply, and those which affect primary production, such as
suspended sediments, light attenuation and water chemistry and temperature, were also
noted to be key and act to influence the food sources consumed by the biological
assemblages of the habitat, and the biological assemblages themselves.
Output processes performed by the biological assemblages are variable between ecological
groups depending on the specific flora and fauna present and the role they perform within
the ecosystem. Of particular importance are the outputs performed by the macroalgae
group, which are diverse in nature and exert influence over other ecological groups in the
habitat. Important output processes from the habitat as a whole include primary and
secondary production, bioengineering, biodeposition (in mixed sediment habitats) and the
supply of propagules; these in turn influence ecosystem functions at the local scale such as
nutrient and biogeochemical cycling, supply of food resources, sediment stability (in mixed
sediment habitats), habitat provision and population and algae control. The export of
biodiversity and organic matter, biodiversity enhancement and biotope stability are the
resulting ecosystem functions that occur at the regional to global scale.
Features within the models that are most useful for monitoring habitat status and change
due to natural variation have been identified, as have those that may be useful for monitoring
to identify anthropogenic causes of change within the ecosystem. Biological, physical and
chemical features of the ecosystem have been identified as potential indicators to monitor
natural variation, whereas biological factors and those physical /chemical factors most likely
to affect primary production have predominantly been identified as most likely to indicate
change due to anthropogenic pressures
Tillin, H. & Tyler-Walters, H., 2014. Assessing the sensitivity of subtidal sedimentary habitats to pressures associated with marine activities. Phase 2 Report – Literature review and sensitivity assessments for ecological groups for circalittoral and offshore Level 5 biotopes. JNCC Report No. 512B, 260 pp.
Human activities within the marine environment give rise to a number of pressures on
seabed habitats. Improved understanding of the sensitivity of subtidal sedimentary habitats
is required to underpin the management advice provided for Marine Protected Areas, as well
as supporting other UK marine monitoring and assessment work. The sensitivity of marine
sedimentary habitats to a range of pressures induced by human activities has previously
been systematically assessed using approaches based on expert judgement for Defra
Project MB0102 (Tillin et al. 2010). This previous work assessed sensitivity at the level of the
broadscale habitat and therefore the scores were typically expressed as a range due to
underlying variation in the sensitivity of the constituent biotopes.
The objective of this project was to reduce the uncertainty around identifying the sensitivity
of selected subtidal sedimentary habitats by assessing sensitivity, at a finer scale and
incorporating information on the biological assemblage, for 33 Level 5 circalittoral and
offshore biotopes taken from the Marine Habitat Classification of Britain and Ireland (Connor
et al. 2004). Two Level 6 sub-biotopes were also included in this project as these contain
distinctive characterising species that differentiate them from the Level 5 parent biotope.
Littoral, infralittoral, reduced and variable salinity sedimentary habitats were excluded from
this project as the scope was set for assessment of circalittoral and offshore sedimentary
communities.
This project consisted of three Phases.
• Phase 1 - define ecological groups based on similarities in the sensitivity of
characterising species from the Level 5 and two Level 6 biotopes described above.
• Phase 2 - produce a literature review of information on the resilience and resistance
of characterising species of the ecological groups to pressures associated with
activities in the marine environment.
• Phase 3 - to produce sensitivity assessment ‘proformas’ based on the findings of
Phase 2 for each ecological group.
This report outlines results of Phase 2.
The Tillin et al., (2010) sensitivity assessment methodology was modified to use the best
available scientific evidence that could be collated within the project timescale. An extensive
literature review was compiled, for peer reviewed and grey literature, to examine current
understanding about the effects of pressures from human activities on circalittoral and
offshore sedimentary communities in UK continental shelf waters, together with information
on factors that contribute to resilience (recovery) of marine species. This review formed the
basis of an assessment of the sensitivity of the 16 ecological groups identified in Phase 1 of
the project (Tillin & Tyler-Walters 2014).
As a result:
• the state of knowledge on the effects of each pressure on circalittoral and offshore
benthos was reviewed;
• the resistance, resilience and, hence, sensitivity of sixteen ecological groups,
representing 96 characteristic species, were assessed for eight separate pressures;
• each assessment was accompanied by a detailed review of the relevant evidence;
Assessing the sensitivity of subtidal sedimentary habitats to pressures associated with human activities
• knowledge gaps and sources of uncertainty were identified for each group;
• each assessment was accompanied by an assessment of the quality of the evidence, its
applicability to the assessment and the degree of concordance (agreement) between the
evidence, to highlight sources of uncertainty as an assessment of the overall confidence
in the sensitivity assessment, and finally
• limitations in the methodology and the application of sensitivity assessments were
outlined.
This process demonstrated that the ecological groups identified in Phase 1 (Tillin & Tyler-Walters
2014) were viable groups for sensitivity assessment, and could be used to represent
the 33 circalittoral and offshore sediments biotopes identified at the beginning of the project.
The results of the sensitivity assessments show:
• the majority of species and hence ecological groups in sedimentary habitats are
sensitive to physical change, especially loss of habitat and sediment extraction, and
change in sediment type;
• most sedimentary species are sensitive to physical damage, e.g. abrasion and
penetration, although deep burrowing species (e.g. the Dublin Bay prawn - Nephrops
norvegicus and the sea cucumber - Neopentadactyla mixta) are able to avoid damaging
effects to varying degrees, depending on the depth of penetration and time of year;
• changes in hydrography (wave climate, tidal streams and currents) can significantly
affect sedimentary communities, depending on whether they are dominated by deposit,
infaunal feeders or suspension feeders, and dependant on the nature of the sediment,
which is itself modified by hydrography and depth;
• sedentary species and ecological groups that dominate the top-layer of the sediment
(either shallow burrowing or epifaunal) remain the most sensitive to physical damage;
• mobile species (e.g. interstitial and burrowing amphipods, and perhaps cumaceans) are
the least sensitive to physical change or damage, and hydrological change as they are
already adapted to unstable, mobile substrata;
• sensitivity to changes in organic enrichment and hence oxygen levels, is variable
between species and ecological groups, depending on the exact habitat preferences of
the species in question, although most species have at least a medium sensitivity to
acute deoxygenation;
• there is considerable evidence on the effects of bottom-contact fishing practices and
aggregate dredging on sedimentary communities, although not all evidence is directly
applicable to every ecological group;
• there is lack of detailed information on the physiological tolerances (e.g. to oxygenation,
salinity, and temperature), habitat preferences, life history and population dynamics of
many species, so that inferences has been made from related species, families, or even
the same phylum;
• there was inadequate evidence to assess the effects of non-indigenous species on most
ecological groups, and
Assessing the sensitivity of subtidal sedimentary habitats to pressures associated with human activities
• there was inadequate evidence to assess the effects of electromagnetic fields and litter
on any ecological group.
The resultant report provides an up-to-date review of current knowledge about the effects of
pressures resulting from human activities of circalittoral and offshore sedimentary
communities. It provides an evidence base to facilitate and support the provision of
management advice for Marine Protected Areas, development of UK marine monitoring and
assessment, and conservation advice to offshore marine industries.
However, such a review will require at least annual updates to take advantage of new
evidence and new research as it becomes available. Also further work is required to test
how ecological group assessments are best combined in practice to advise on the sensitivity
of a range of sedimentary biotopes, including the 33 that were originally examined
Marine Evidence-based Sensitivity Assessment (MarESA) – A Guide
The Marine Evidence-based Sensitivity Assessment (MarESA) methodology was developed by the Marine Life Information Network (MarLIN) team at the Marine Biological Association of the UK. The following guide details the approach, its assumptions, and its application to sensitivity assessment.
The guide discusses:
• key terms used in sensitivity assessment;
• the definitions and terms used in the MarESA approach;
• its assumptions;
• the definition of resistance, resilience and sensitivity;
• the definition of pressures and their benchmarks;
• the step by step process by which the possible sensitivity of each feature (habitat, biotope or species) to each pressure is assessed;
• the interpretation and application of evidence to sensitivity assessments on a pressure by pressure basis; and
• limitations in the application of sensitivity assessments in management.
The MarESA methodology provides a systematic process to compile and assess the best available scientific evidence to determine each sensitivity assessment. The evidence used is documented throughout the process to provide an audit trail to explain each sensitivity assessment. Unlike other expert-based approaches, this means that the MarESA assessments can be repeated and updated.
The resultant 'evidence base' is the ultimate source of information for the application of the sensitivity assessments to management and planning decisions. The MarESA dataset and MarLIN website represent the largest review of the potential effects of human activities and natural events on the marine and coastal habitats of the North East Atlantic yet undertaken
Assessing the sensitivity of blue mussel beds to pressures associated with human activities.
The Joint Nature Conservation Committee (JNCC) commissioned this project to generate an
improved understanding of the sensitivities of blue mussel (Mytilus edulis) beds, found in UK
waters, to pressures associated with human activities in the marine environment. The work
will provide an evidence base that will facilitate and support management advice for Marine
Protected Areas, development of UK marine monitoring and assessment, and conservation
advice to offshore marine industries.
Blue mussel beds are identified as a Habitat of Principle Importance (HPI) under the Natural
Environment and Rural Communities (NERC) Act 2006, as a Priority Marine Feature (PMF)
under the Marine (Scotland) Act 2010, and included on the OSPAR (Annex V) list of
threatened and declining species and habitats.
The purpose of this project was to produce sensitivity assessments for the blue mussel
biotopes included within the HPI, PMF and OSPAR habitat definitions, and clearly document
the supporting evidence behind the assessments and any differences between them.
A total of 20 pressures falling in five categories - biological, hydrological, physical damage,
physical loss, and pollution and other chemical changes - were assessed in this report. The
review examined seven blue mussel bed biotopes found on littoral sediment and sublittoral
rock and sediment. The assessments were based on the sensitivity of M. edulis rather than
associated species, as M. edulis was considered the most important characteristic species in
blue mussel beds.
To develop each sensitivity assessment, the resistance and resilience of the key elements
are assessed against the pressure benchmark using the available evidence gathered in this
review. The benchmarks were designed to provide a ‘standard’ level of pressure against
which to assess sensitivity. Blue mussel beds were highly sensitive to a few human
activities:
• introduction or spread of non-indigenous species (NIS);
• habitat structure changes - removal of substratum (extraction); and
• physical loss (to land or freshwater habitat).
Physical loss of habitat and removal of substratum are particularly damaging pressures,
while the sensitivity of blue mussel beds to non-indigenous species depended on the
species assessed. Crepidula fornicata and Crassostrea gigas both had the potential to outcompete
and replace mussel beds, so resulted in a high sensitivity assessment.
Mytilus spp. populations are considered to have a strong ability to recover from
environmental disturbance. A good annual recruitment may allow a bed to recovery rapidly,
though this cannot always be expected due to the sporadic nature of M. edulis recruitment.
Therefore, blue mussel beds were considered to have a 'Medium' resilience (recovery within
2-10 years). As a result, even where the removal or loss of proportion of a mussel bed was
expected due to a pressure, a sensitivity of 'Medium' was reported. Hence, most of the
sensitivities reported were 'Medium'. It was noted, however, that the recovery rates of blue
mussel beds were reported to be anywhere between two years to several decades.
In addition, M. edulis is considered very tolerant of a range of physical and chemical
conditions. As a result, blue mussel beds were considered to be 'Not sensitive' to changes
in temperature, salinity, de-oxygenation, nutrient and organic enrichment, and substratum
type, at the benchmark level of pressure.
The report found that no distinct differences in overall sensitivity exist between the HPI, PMF
and OSPAR definitions. Individual biotopes do however have different sensitivities to
pressures, and the OSPAR definition only includes blue mussel beds on sediment. These
differences were determined by the position of the habitat on the shore and the sediment
type. For example, the infralittoral rock biotope (A3.361) was unlikely to be exposed to
pressures that affect sediments. However in the case of increased water flow, mixed
sediment biotopes were considered more stable and ‘Not sensitive’ (at the benchmark level)
while the remaining biotopes were likely to be affected.
Using a clearly documented, evidence-based approach to create sensitivity assessments
allows the assessment basis and any subsequent decision making or management plans to
be readily communicated, transparent and justifiable. The assessments can be replicated
and updated where new evidence becomes available ensuring the longevity of the sensitivity
assessment tool. For every pressure where sensitivity was previously assessed as a range
of scores in MB0102, the assessments made by the evidence review have supported one of
the MB0102 assessments. The evidence review has reduced the uncertainty around
assessments previously undertaken in the MB0102 project (Tillin et al., 2010) by assigning a
single sensitivity score to the pressures as opposed to a range. Finally, as blue mussel bed
habitats also contribute to ecosystem function and the delivery of ecosystem services,
understanding the sensitivity of these biotopes may also support assessment and
management in regard to these.
Whatever objective measures are applied to data to assess sensitivity, the final sensitivity
assessment is indicative. The evidence, the benchmarks, the confidence in the
assessments and the limitations of the process, require a sense-check by experienced
marine ecologists before the outcome is used in management decisions
Conceptual Ecological Modelling of Sublittoral Rock Habitats to Inform Indicator Selection
The purpose of this study is to produce a series of Conceptual Ecological Models (CEMs)
that represent sublittoral rock habitats in the UK. CEMs are diagrammatic representations of
the influences and processes that occur within an ecosystem. They can be used to identify
critical aspects of an ecosystem that may be studied further, or serve as the basis for the
selection of indicators for environmental monitoring purposes. The models produced by this
project are control diagrams, representing the unimpacted state of the environment free from
anthropogenic pressures.
It is intended that the models produced by this project will be used to guide indicator
selection for the monitoring of this habitat in UK waters. CEMs may eventually be produced
for a range of habitat types defined under the UK Marine Biodiversity Monitoring R&D
Programme (UKMBMP), which, along with stressor models, are designed to show the
interactions within impacted habitats, would form the basis of a robust method for indicator
selection. This project builds on the work to develop CEMs for shallow sublittoral coarse
sediment habitats (Alexander et al 2014).
The project scope included those habitats defined as ‘sublittoral rock’. This definition
includes those habitats that fall into the EUNIS Level 3 classifications A3.1 Atlantic and
Mediterranean high energy infralittoral rock, A3.2 Atlantic and Mediterranean moderate
energy infralittoral rock, A3.3 Atlantic and Mediterranean low energy infralittoral rock, A4.1
Atlantic and Mediterranean high energy circalittoral rock, A4.2 Atlantic and Mediterranean
moderate energy circalittoral rock, and A4.3 Atlantic and Mediterranean low energy
circalittoral rock as well as the constituent Level 4 and 5 biotopes that are relevant to UK
waters. A species list of characterising fauna to be included within the scope of the models
was identified using an iterative process to refine the full list of species found within the
relevant Level 5 biotopes.
A literature review was conducted using a pragmatic and iterative approach to gather
evidence regarding species traits and information that would be used to inform the models
and characterise the interactions that occur within the sublittoral rock habitat. All information
gathered during the literature review was entered into a data logging pro-forma spreadsheet
that accompanies this report. Wherever possible, attempts were made to collect information
from UK-specific peer-reviewed studies, although other sources were used where
necessary. All data gathered was subject to a detailed confidence assessment. Expert
judgement by the project team was utilised to provide information for aspects of the models
for which references could not be sourced within the project timeframe.
A multivariate analysis approach was adopted to assess ecologically similar groups (based
on ecological and life history traits) of fauna from the identified species to form the basis of
the models. A model hierarchy was developed based on these ecological groups. One
general control model was produced that indicated the high-level drivers, inputs, biological
assemblages, ecosystem processes and outputs that occur in sublittoral rock habitats. In
addition to this, seven detailed sub-models were produced, which each focussed on a
particular ecological group of fauna within the habitat: ‘macroalgae’, ‘temporarily or
permanently attached active filter feeders’, ‘temporarily or permanently attached passive
filter feeders’, ‘bivalves, brachiopods and other encrusting filter feeders’, ‘tube building
fauna’, ‘scavengers and predatory fauna’, and ‘non-predatory mobile fauna’. Each sub-model
is accompanied by an associated confidence model that presents confidence in the links
between each model component. The models are split into seven levels and take spatial and
temporal scale into account through their design, as well as magnitude and direction of
influence. The seven levels include regional to global drivers, water column processes, local
inputs/processes at the seabed, habitat and biological assemblage, output processes, local
ecosystem functions, and regional to global ecosystem functions.
The models indicate that whilst the high level drivers that affect each ecological group are
largely similar, the output processes performed by the biota and the resulting ecosystem
functions vary both in number and importance between groups. Confidence within the
models as a whole is generally high, reflecting the level of information gathered during the
literature review.
Physical drivers which influence the ecosystem were found to be of high importance for the
sublittoral rock habitat, with factors such as wave exposure, water depth and water currents
noted to be crucial in defining the biological assemblages. Other important factors such as
recruitment/propagule supply, and those which affect primary production, such as
suspended sediments, light attenuation and water chemistry and temperature, were also
noted to be key and act to influence the food sources consumed by the biological
assemblages of the habitat, and the biological assemblages themselves.
Output processes performed by the biological assemblages are variable between ecological
groups depending on the specific flora and fauna present and the role they perform within
the ecosystem. Of particular importance are the outputs performed by the macroalgae
group, which are diverse in nature and exert influence over other ecological groups in the
habitat. Important output processes from the habitat as a whole include primary and
secondary production, bioengineering, biodeposition (in mixed sediment habitats) and the
supply of propagules; these in turn influence ecosystem functions at the local scale such as
nutrient and biogeochemical cycling, supply of food resources, sediment stability (in mixed
sediment habitats), habitat provision and population and algae control. The export of
biodiversity and organic matter, biodiversity enhancement and biotope stability are the
resulting ecosystem functions that occur at the regional to global scale.
Features within the models that are most useful for monitoring habitat status and change
due to natural variation have been identified, as have those that may be useful for monitoring
to identify anthropogenic causes of change within the ecosystem. Biological, physical and
chemical features of the ecosystem have been identified as potential indicators to monitor
natural variation, whereas biological factors and those physical /chemical factors most likely
to affect primary production have predominantly been identified as most likely to indicate
change due to anthropogenic pressures
Assessing the sensitivity of Sabellaria spinulosa to pressures associated with marine activities.
The Joint Nature Conservation Committee (JNCC) commissioned this project to generate an
improved understanding of the sensitivities of Sabellaria spinulosa reefs based on the
OSPAR habitat definition. This work aimed to provide an evidence base to facilitate and
support management advice for Marine Protected Areas, development of UK marine
monitoring and assessment, and conservation advice to offshore marine industries.
The OSPAR list of threatened and declining species and habitats refers to subtidal S.
spinulosa reefs on hard or mixed substratum. S. spinulosa may also occur as thin crusts or
individual worms but these are not the focus of conservation. The purpose of this project
was to produce sensitivity assessments with supporting evidence for S. spinulosa reefs,
clearly documenting the evidence behind the assessments and the confidence in these
assessments.
Sixteen pressures, falling in five categories - biological, hydrological, physical damage,
physical loss, and pollution and other chemical changes - were assessed in this report. To
develop each sensitivity assessment, the resistance and resilience of the key elements of
the habitat were assessed against the pressure benchmark using the available evidence.
The benchmarks were designed to provide a ‘standard’ level of pressure against which to
assess sensitivity. The highest sensitivity (‘medium’) was recorded for physical pressures
which directly impact the reefs including:
• habitat structure changes – removal of substratum;
• abrasion and penetration and sub-surface disturbance;
• physical loss of habitat and change to habitat; and
• siltation rate changes including and smothering.
The report found that no evidence for differences in the sensitivity of the three EUNIS S.
spinulosa biotopes that comprise the OSPAR definition. However, this evidence review has
identified significant information gaps regarding sensitivity, ecological interactions with other
species and resilience. No clear difference in resilience was established across the OSPAR
S. spinulosa biotopes that were assessed in this report. Using a clearly documented,
evidence based approach to create sensitivity assessments allows the assessment and any
subsequent decision making or management plans to be readily communicated, transparent
and justifiable. The assessments can be replicated and updated where new evidence
becomes available ensuring the longevity of the sensitivity assessment tool. Finally, as S.
spinulosa habitats may also contribute to ecosystem function and the delivery of ecosystem
services, understanding the sensitivity of these biotopes may also support assessment and
management in regard to these.
Whatever objective measures are applied to data to assess sensitivity, the final sensitivity
assessment is indicative. The evidence, the benchmarks, the confidence in the
assessments and the limitations of the process, require a sense-check by experienced
marine ecologists before the outcome is used in management decisions