Macrozoobenthic soft-sediment communities of central Arctic Kongsfjorden inhabiting six depth zones between 5 and 30 m were sampled using SCUBA-diving during June-August 2003 and analysed comparatively. About 63 taxa were found, nine of which had not been reported for Kongsfjorden and four for Svalbard. Suspension feeding or surface and sub-surface detritivorous polychaetes and deposit-feeding amphipods were dominant. Only 11 of the 63 taxa (45 species and additional 18 families not further identiWed) inhabited the complete depth range. Biomass ranged from 3.5 to 25.0 g ash free dry mass m ¡2 and mean Shannon diversity (Log e) was 2.06. Similarity clustering from abundance and biomass data showed a signiWcant diVerence between the shallow station (5 m) and the rest. The latter formed two sub-groups (10-20 and 25-30 m). Depth is irrevocably correlated with icescouring. Thus the diVerences in diversity together with the predicted iceberg scour intensity support the 'intermediate disturbance hypothesis' indicating that habitats impacted by moderate iceberg scouring enable higher diversity. In contrast, biotopes frequently aVected only host pioneer communities, while mature, less diverse assemblages dominate depths of low impact.
The reproductive cycle and gonad development of the yellow clam Mesodesma mactroides was studied over a period of 24 months (January 2005-December 2006 at the Argentinean sandy beach Santa Teresita. Histological examination of gonadal tissue revealed that sex ratios did not significantly deviate from the proportion of 1:1 and no case of hermaphroditism was found. The reproductive cycle of M. mactroides followed an annual cyclicality, which was significantly correlated to monthly mean sea surface temperatures (SST). Oocytes showed highest abundance in winter, indicating a process of gonadal development and sexual maturation. The mean oocyte size decreased significantly during spring. Modal oocyte sizes decreased significantly during winter and late spring of each year, suggesting spawning events. The condition index was not useful in describing the annual reproductive cycle of M. mactroides. Ash-free, shell-free dry mass was chosen to detect the condition of the specimens, and this significantly correlated with monthly mean SST and the gametogenic cycle. Annual recruitment patterns during summer-autumn indicated a 3-month-long planktonic phase of M. mactroides. The reproduction cycle and gonad development of M. mactroides showed only weak differences between data from the present study and those collected 40 years ago.
Local species diversity may be determined by processes operating locally, such as disturbance, predation and competition, or by regional processes, such as environmental structuring or history. Classical theory focusing on competition predicts that the species combining to form communities will be less similar to each other than they would be if they were assembled at random from a regional species pool. Theory focusing on environmental structuring predicts that species will be more similar to each other than expected by chance. A randomisation test that determines the extent to which local species lists represent random selections from a regional list, based on the average relatedness between species, was applied to data held in the MacroBen database. Little or no evidence was found for species lists of whole faunas at any scale being random subsets of species lists at larger scales. Species tend to be more closely related to each other than would be expected if they were assembled at random. Thus marine soft-sediment macrofauna are not locally assembled at random from regional species pools and it is likely that regional processes determine the assembly of communities. Focusing on the most abundant class within the macrofauna, a different pattern emerges, in that there is a much stronger tendency for local polychaete composition to be a random subset from regional pools at all scales. Thus it is not possible to determine whether local polychaete diversity is independent of both local and regional processes, or determined by a combination of both acting antagonistically.
The pan-European MacroBen database was used to compare the AZTI Marine Biotic Index (AMBI) and the Benthic Quality Index (BQI ES ), 2 biotic indices which rely on 2 distinct assessments of species sensitivity/tolerance (i.e. AMBI EG and BQI E[S 50 ] 0.05 ) and which up to now have only been compared on restricted data sets. A total of 12 409 stations were selected from the database. This subset (indicator database) was later divided into 4 marine and 1 estuarine subareas. We computed E(S 50 ) 0.05 in 643 taxa, which accounted for 91.8% of the total abundances in the whole marine indicator database. AMBI EG and E(S 50 ) 0.05 correlated poorly. Marked heterogeneities in E(S 50 ) 0.05 between the marine and estuarine North Sea and between the 4 marine subareas suggest that sensitivity/tolerance levels vary among geographical areas. High values of AMBI were always associated with low values of BQI ES , which underlines the coherence of these 2 indices in identifying stations with a bad ecological status (ES). Conversely, low values of AMBI were sometimes associated with low values of BQI ES resulting in the attribution of a good ES by AMBI and a bad ES by BQI ES . This was caused by the dominance of species classified as sensitive by AMBI and tolerant by BQI ES . Some of these species are known to be sensitive to natural disturbance, which highlights the tendency of BQI ES to automatically classify dominant species as tolerant. Both indices thus present weaknesses in their way of assessing sensitivity/tolerance levels (i.e. existence of a single sensitivity/tolerance list for AMBI and the tight relationship between dominance and tolerance for BQI ES ). Future studies should focus on the (1) clarification of the sensitivity/tolerance levels of the species identified as problematic, and (2)
We describe an integrated database on European macrobenthic fauna, developed within the framework of the European Network of Excellence MarBEF, and the data and data integration exercise that provided its content. A total of 44 datasets including 465 354 distribution records from soft-bottom macrobenthic species were uploaded into the relational MacroBen database, corresponding to 22 897 sampled stations from all European seas, and 7203 valid taxa. All taxonomic names were linked to the European Register of Marine Species, which was used as the taxonomic reference to standardise spelling and harmonise synonymy. An interface was created, allowing the user to explore, subselect, export and analyse the data by calculating different indices. Although the sampling techniques and intended use of the datasets varied tremendously, the integrated database proved to be robust, and an important tool for studying and understanding large-scale long-term distributions and abundances of marine benthic life. Crucial in the process was the willingness and the positive data-sharing attitude of the different data contributors. Development of a data policy that is highly aware of sensitivities and ownership issues of data providers was essential in the creation of this goodwill.
The yellow clam Mesodesma mactroides (Bivalvia: Mesodesmatidae) was once the most abundant intertidal species on the Atlantic coast of northern Argentina and an important commercial resource in South America. This study of a population inhabiting the intertidal zone of the sheltered-dissipative sandy beach Santa Teresita documents the species' population biology, including demographic structure, growth and production during December 2004 and December 2006, and adumbrates the critical state of M. mactroides at present. A total of 3,015 M. mactroides were collected and measured, whereas individuals were found with an anterior-posterior shell length between 2 and 64 mm. A von Bertalanffy growth function with an asymptotic length (L ? ) of 85 mm and a growth constant (K) of 0.47 year -1 was established from length-frequency distributions. The longevity of the species is estimated at approximately 6 years, and instantaneous mortality rate was about three times higher than 40 years ago. Besides, this study confirmed that the overall growth performance index (OGP) is habitat-specific and can be used to group M. mactroides and M. donacium from different areas into temperate and upwelling species. Furthermore, OGP is inversely correlated with the latitudinal distribution of Mesodesma populations. The intertidal biomass ranged between 0.06 and 0.07 g AFDM m -2 year -1 . Individual production was observed to be highest at 47 mm length (0.35 g AFDM m -2 year -1 ), and annual production ranged between 0.12 and 0.19 g AFDM m -2 year -1 , resulting in productivity values (P/B) between 1.84 and 2.93. The comparison of the results of the present study with those of growth studies conducted on M. mactroides 40 years ago revealed the following considerable differences in the population structure of M. mactroides, indicating the conservation status of this intertidal bivalve as endangered: (1) present growth rates are faster, but that the maximum length attained has decreased, (2) the numbers of individuals per square metre were many times higher in the past than in the present, (3) bivalves from the present work never reached the 'commercial size' of 60 mm and (4) 40 years ago, the population of M. mactroides was composed of up to three cohorts, whereas in this study, there was only one single cohort visible.
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