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ABSTRACT: a b s t r a c t An assessment procedure for determining the ecological quality status of soft-sediment benthic habitats requires the following aspects: (1) habitat assignation of the samples (habitat approach), (2) reference or target conditions for the benthic parameters (reference approach), and (3) the selection of indicator tools to assess the relative quality status (indicator approach). For all these aspects, different approaches exist, and the indicator selection and reference approaches are largely documented. The aspect of the habitat approach is sometimes neglected, but is essential in determining the reference conditions per habitat type. Benthic habitats differ in structure and function, and as such will show wide variations in statistics or measures between habitats. A major problem, mainly in coastal soft-bottom systems, is to track the deviation lines within data of the different benthic habitat types. This study shows that both a classical community analysis and the use of habitat suitability maps seem to be appropriate tools, but further fine-tuning is necessary. For the second assessment step, an objective assessment of reference conditions is a challenge in areas lacking pristine or minimally disturbed sites, and areas of which historic data are not available. This can be remedied by using a dataset of the area with a good spatial and temporal coverage of the benthic data, thereby avoiding data originating from highly impacted areas. For the third aspect in the assessment procedure, we recommend the use of different indicators with different properties (parameters, algorithms) since it indicates their weaknesses and strengths in the local region. In general, this study showed us that it is valuable to test different existing approaches for EcoQ assess-ment in a local area, revealing strengths, weaknesses and shortcomings within the assessment regarding data, habitat identification, monitoring strategy, reference settings and indicator use. All these aspects need to be taken into account within an ecological quality status assessment of an area in order to improve its confidence.
Ecological Indicators 02/2013; 25:266-278. · 2.69 Impact Factor
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ABSTRACT: The common tube-building polychaete Lanice conchilega is known as a habitat structuring species and can form dense aggregations. The effects of L. conchilega on the surrounding benthic community have received little attention, especially in subtidal areas. Therefore, the presence
of L. conchilega in different habitats in the North Sea and its effect on the abundance, species richness, diversity and community structure
in these habitats are evaluated in the present paper, based on data from the ICES North Sea Benthos Survey of 2000. Lanice conchilega has a wide geographical distribution and a low habitat specialization, but optimally occurs in shallow fine sands. In the
present study, the presence of L. conchilega resulted in a density increase and a significant (positive) correlation of the benthos density with the density of L. conchilega. Furthermore, the species richness (number of species) increased with increasing density of L. conchilega. This trend was, however, not consistent: the number of species reached more or less an asymptotic value or even decreased
after reaching a critical density of L. conchilega (>500–1,000ind/m²), as observed in shallow fine sands. The same overall pattern was detected concerning the expected number
of species. The N
1-diversity index showed similar or slightly higher values in L. conchilega patches compared to patches without L. conchilega. From the results of the community analysis, it can be concluded that the species, which were responsible for the increase
of the diversity, belonged to the overall species-pool of that habitat. The effects on density and diversity differed between
the four discerned habitats (shallow muddy sand, shallow fine sand, shallow medium sand and deep fine sand), and were most
pronounced in shallow fine sands. These patterns can be attributed to the habitat structuring capacity of L. conchilega. The mechanisms responsible for the increase of the habitat quality in patches of L. conchilega can be summarized as (1) changes in the hydrodynamics, (2) increases of the habitat stability and oxygen supply, and (3)
a creation of habitat heterogeneity in a uniform environment. In this way, L. conchilega alters the habitat characteristics and affects other organisms, and can therefore even be considered as an ecosystem engineer.
In other words, L. conchilega patches are responsible for an increased habitat quality in an otherwise uniform habitat, which results in a higher survival
of the surrounding benthic species.
Marine Biology 04/2012; 154(6):1009-1019. · 2.28 Impact Factor
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ABSTRACT: The tube building polychaete Lanice conchilega is a common and ecologically important species in intertidal and shallow subtidal sands. It builds a characteristic tube with ragged fringes and can retract rapidly into its tube to depths of more than 20cm. Therefore, it is very difficult to sample L. conchilega individuals, especially with a Van Veen grab. Consequently, many studies have used tube counts as estimates of real densities. This study reports on some aspects to be considered when using tube counts as a density estimate of L. conchilega, based on intertidal and subtidal samples. Due to its accuracy and independence of sampling depth, the tube method is considered the prime method to estimate the density of L. conchilega. However, caution is needed when analyzing samples with fragile young individuals and samples from areas where temporary physical disturbance is likely to occur.
Helgoland Marine Research 04/2012; 60(4):317-321. · 1.28 Impact Factor
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Gert Van Hoey,
Angel Borja,
Silvana Birchenough,
Lene Buhl-Mortensen,
Steven Degraer,
Dirk Fleischer,
Francis Kerckhof,
Paolo Magni,
Iñigo Muxika,
Henning Reiss,
Alexander Schröder,
Michael L Zettler
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ABSTRACT: The Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD) are the European umbrella regulations for water systems. It is a challenge for the scientific community to translate the principles of these directives into realistic and accurate approaches. The aim of this paper, conducted by the Benthos Ecology Working Group of ICES, is to describe how the principles have been translated, which were the challenges and best way forward. We have tackled the following principles: the ecosystem-based approach, the development of benthic indicators, the definition of 'pristine' or sustainable conditions, the detection of pressures and the development of monitoring programs. We concluded that testing and integrating the different approaches was facilitated during the WFD process, which led to further insights and improvements, which the MSFD can rely upon. Expert involvement in the entire implementation process proved to be of vital importance.
Marine pollution bulletin 11/2010; 60(12):2187-96. · 2.63 Impact Factor
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ABSTRACT: Within the frame of different research projects, a large number of sites at the Belgian Continental Shelf (BCS) have been sampled for the macrobenthos between 1994 and 2000. These samples cover a diverse range of habitats: from the sandy beaches to the open sea, from the gullies between the sandbanks to the tops of the sandbanks, and from clay to coarse sandy sediments. To investigate the large-scale spatial distribution of the macrobenthos of the Belgian Continental Shelf, the data of all these research projects—728 samples—were combined and analysed. By means of several multivariate techniques, 10 sample groups with similar macrobenthic assemblage structure were distinguished. Each sample group is found in a particular physico-chemical environment and has a specific species composition. Four sample groups differ drastically, both in habitat and species composition, and are considered to represent four macrobenthic communities: (1) the muddy fine sand Abra alba–Mysella bidentata community is characterized by high densities and diversity; (2) the Nephtys cirrosa community occurs in well-sorted sandy sediments and is characterized by low densities and diversity; (3) very low densities and diversity typify the Ophelia limacina–Glycera lapidum community, which is found in coarse sandy sediments and (4) the Eurydice pulchra–Scolelepis squamata community is typical for the upper intertidal zone of sandy beaches. These macrobenthic communities are not isolated from each other, but are linked through six transitional species assemblages. The transition between the A. alba–M. bidentata community and the N. cirrosa community is characterized by a reduction in the mud content and is dominated by Magelona johnstoni. The transition between the N. cirrosa and the O. limacina–G. lapidum community is distinctive by decreasing densities and coincides with a gradual transition between medium and coarse sandy sediments. From the N. cirrosa to the E. pulchra–S. squamata community, transitional species assemblages related to the transition from the subtidal to the intertidal environment were found. Each community or transitional species assemblages was found over a specific range along the onshore–offshore gradient, four types can be discerned: (1) almost restricted to the near-shore area, but possible wider distribution; (2) distributed over the full onshore–offshore gradient; (3) restricted to the near-shore area and (4) restricted to the sandy beach environment. The diversity pattern on the BCS follows this division, with species rich and poor assemblages in the near-shore area to only species poor assemblages more offshore. The distribution and diversity patterns are linked to the habitat type, distinguished by median grain size and mud content.
Estuarine, Coastal and Shelf Science.
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ABSTRACT: This paper evaluates the effect of the tube-building, habitat structuring polychaete Lanice conchilega on the macrobenthic community and sediment characteristics of its habitat. To investigate which factors make species occur in a well-known bio-engineered habitat, macrofaunal and sedimentological data, gathered over a period of 10 years in a shallow, fine sediment bottom of the Belgian Part of the North Sea, were submitted to analyses. Both sediment composition and community structure of the associated macrofaunal matrix were affected by the presence of L. conchilega. The effect of the protruding tubes on hydrodynamics clearly resulted in the retention of fine sediment particles, while the increased coarse fraction was assumed to reflect a dynamic population build-up. This study confirmed that tube aggregations of L. conchilega expand the realized niche of several species without forming their own association. A species rank list was created according to each species' association with L. conchilega. This species rank list is extensively discussed based on all ecological knowledge available. Species are favoured by the habitat modifying ability of the polychaete tubes, which create and regulate refuge for species, alter the interactions between local species and change the physical factors of the environment. This descriptive and correlative data study examines the ecological importance of the bio-engineer L. conchilega on species level.
Estuarine, Coastal and Shelf Science.
