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Marine biofouling is a natural process that represents major economic, environmental, and health concerns. Some booster biocides have been used in biofouling control, however, they were found to accumulate in environmental compartments, showing negative effects on marine organisms. Therefore, it is urgent to develop new eco-friendly alternatives. Phenyl ketones, such as benzophenones and acetophenones, have been described as modulators of several biological activities, including antifouling activity (AF). In this work, acetophenones were combined with other chemical substrates through a 1,2,3-triazole ring, a strategy commonly used in Medicinal Chemistry. In our approach, a library of 14 new acetophenone–triazole hybrids was obtained through the copper(I)-catalyzed alkyne-azide cycloaddition “click” reaction. All of the synthesized compounds were evaluated against the settlement of a representative macrofouling species, Mytilus galloprovincialis, as well as on biofilm-forming marine microorganisms, including bacteria and fungi. The growth of the microalgae Navicula sp. was also evaluated after exposure to the most promising compounds. While compounds 6a, 7a, and 9a caused significant inhibition of the settlement of mussel larvae, compounds 3b, 4b, and 7b were able to inhibit Roseobacter litoralis bacterial biofilm growth. Interestingly, acetophenone 7a displayed activity against both mussel larvae and the microalgae Navicula sp., suggesting a complementary action of this compound against macro- and microfouling species. The most potent compounds (6a, 7a, and 9a) also showed to be less toxic to the non-target species Artemia salina than the biocide Econea®. Regarding both AF potency and ecotoxicity activity evaluation, acetophenones 7a and 9a were put forward in this work as promising eco-friendly AF agents.

Summer growth reduction in juvenile flatfish has been observed in various temperate coastal areas, suggesting a general mechanism. One possible mechanism that might explain this phenomenon is related to trophic limitation. After the spring phytoplankton bloom macrozoobenthic infauna becomes less active above the sediment, thereby affecting the time spent by predatory flatfish on searching for prey and hence, causing a reduction in food intake and in growth. Here, our aim is to gather evidence to substantiate this so-called “summer growth reduction” hypothesis by analyzing summer growth for 0-group flounder Platichthys flesus at the Balgzand intertidal area in the western Dutch Wadden Sea, under the prediction that flounder, as a more epibenthic predator, would suffer less or not at all from summer growth reduction in contrast to 0-group plaice Pleuronectes platessa, a more benthic feeder. Summer growth was studied for three contrasting years with respect to preceding winter water temperature conditions (cold, average and warm year) to exclude possible irreversible non-genetic adaptation of growth to water temperature conditions. Growth performance was analyzed by combining information on individual growth based on otolith daily ring analysis with predictions of maximum growth (= under optimal food conditions) based on a Dynamic Energy Budget model. In line with expectations and in contrast to 0-group plaice, no trend in growth performance over time was found suggesting that 0-group flounder showed no growth reduction after summer, providing further basis for a future testing of the trophic limitation hypothesis

Razor clam species are commercially important worldwide. In Tunisia, studies on razor clams aim to promote harvesting and ensure a rational and durable exploitation. In Tunisia, Solen marginatus (Pulteney, 1799) is the most abundant razor clam species although Ensis species, particularly Ensis minor, are also found. The aim of this study is to understand the allocation strategies of S. marginatus in terms of growth and reproduction. For that, condition indices and histological analysis were performed and related to temperature and chlorophyll a. Clams were collected monthly in the southern Mediterranean Sea (Gulf of Gabes, Tunisia). Body and somatic mass increased in summer and autumn. Body condition was highest in September 2007 and the highest somatic condition index was measured in August 2008. Body and somatic mass loss occurred in winter and late spring-early summer with lowest values found, respectively, in February and May 2008. Gametogenesis rate was slow and held in a synchronous way dur...

In this paper, life history characteristics of tropical flatfishes occurring at the fringing reefs of Curacao to a depth of 20m were studied. In total four flatfish species were caught, three common Bothidae species: the eyed flounder Bothus ocellatus, the mottled or maculated flounder B. maculiferus and the peacock flounder B. lunatus,and –in small numbers- the channel flounder Syacium micrurum. B. ocellatus and S. micrurum only occurred in sandy moats on the shallow reef terrace and fore reef and between coral patches on the terrace and fore reefslope. The other species could also be found on coral patches. The depth distribution of the various species overlapped: all species were caught over a depth range from a few meters up to 20 m. All Bothus species were carnivores, preying on a variety of mobile benthic animals such as fishes and crustaceans. Reproduction seemed to occur year round in all three Bothus species. Growth between the species varied considerably with a maximumage found in B. maculiferus and B. lunatus of a little over 1 year, and in B. ocellatus of about 2 years. Growth was lowest in B. ocellatus and highest in B. lunatus: after one year B. ocellatus was about 10 cm in size, B. maculiferus25 cm and B. lunatus about 35 cm. After correction for differences in water temperature, the Bothus species showed a similar variability and range in growth rate as some temperate and subtropical flatfish species. These observations do not fit the hypothesis postulated by Pauly (1994) of an increasing importance of food-limitation in juvenile flatfish with decreasing latitude, despite the low densities and biomass of benthic in- and epifauna inthe soft sediments in mangroves, seagrass beds and the reefs of Curacao.

This paper analyses the population dynamics, growth and feeding ecology ofDicentrarchus labraxin order to gain a better understanding of its present role in the western Dutch Wadden Sea ecosystem. Otolith analysis showed that the population is mostly comprised of individuals aged 3–5 years old and between 20 and 45 cm in length. In autumn, 0-group juveniles are also an important part of the population. Both juveniles and adults use the area as a feeding ground exhibiting an opportunistic feeding strategy that relies on available prey, especially the brown shrimpCrangon crangon. Stomach content analysis and nitrogen stable isotope analysis showed an ontogenetic shift towards piscivory and a general decrease in the dominance of invertebrates with increasing size. Over the last 50 years, large between-year fluctuations inD. labraxabundance have been observed with an underlying increasing trend from about 1990 until 2007 followed by a subsequent decline. Spring abundance showed significant relationships with temperature and salinity while autumn abundance was only related to temperature. Spring and autumnD. labraxabundance were also strongly related to abundance of brown shrimpC. crangonprey. Long-term trends in temperature and salinity in the area suggest that environmental conditions for juvenile growth have become optimal, resulting in increased abundance since the mid-1980s. Continued monitoring of the dynamics of this species in the Dutch Wadden Sea is important to understand and anticipate the effects of climate change on theD. labraxpopulation and its role in the local food web.

The shanny Lipophrys pholis is an intertidal fish commonly found in Portuguese coastalwaters. Spawning takes place from early autumn to mid spring, after which demersal eggshatch and larvae disperse along the coast. Two to three months later, young juvenilesreturn to the tide pools to settle. However, information on fish movement, habitatconnectivity and population structure is scarce for this species. One hundred and twentyearly juveniles (16–35 mm) were collected in April 2014 from six rocky beaches along thewestern and south Portuguese coasts (Agudela, Cabo do Mundo, Boa Nova, Peniche, Sinesand Olhos de Água). δ18O and δ13C were determined by isotope-ratio mass spectrometry.Data were analysed to determine whether isotopic signatures could be used to assess thedegree of separation between individuals collected from different locations. Mean δ13Cand δ18O values ranged from −0.02‰ to 1.14‰ and −7.77‰ to −6.62‰, respectively.Both seawater temperature and salinity caused differences in otolith δ18O among the fourmain sampling areas. The variation among areas in δ13C was most likely related toslight differences in the diet, growth and metabolism of fish. The distinct isotopicsignatures, at least for the northern and central areas, suggested low levels of connectivityacross large spatial scales during the juvenile stage. Furthermore, similar isotopicsignatures within the same area indicated some degree of larval oceanic retention at shortspatial scales. This study suggests that stable isotope records in otoliths could provideinformation about the home residency, movements and habitat connectivity of intertidalfishes.

Individual age is a key parameter when studying population dynamics of a species. However, accurate age determination in bivalve shells is not always straightforward due to the difficulty of using external growth lines on the shell surface as a reliable method to identify annual growth patterns. In the present paper, we aimed at validating the seasonality in growth lines in the shell of Macoma balthica using stable oxygen and carbon isotopes (delta O-18 and delta C-13) as well as trace elements (Sr, Mn, Mg and Ca).During a 1-year growth experiment, delta O-18 values in the shell carbonate peaked in February/March and matched the annual line visible in the acetate peel of the shell's cross-section. Most carbonate was deposited in the months March to May, which was supported by the observed fast growth in the experiment during this period. Growth stopped between October and December indicating that annual growth lines are formed due to autumn growth stop. Fast growth occurs mainly at temperatures above 6-7 degrees C, although growth may already start at temperatures of about 5 degrees C.delta C-13 profiles did not show any clear seasonality related to the position of the growth lines on the valve or acetate peel and, therefore, cannot be used to estimate age. Along the hinge, Sr was the only element showing variation on the growth lines. High Sr/Ca ratios in the hinge occurred near annual growth lines identified in the acetate peel, suggesting that Sr/Ca ratios may be used to identify annual growth lines and estimate age in M. balthica. Furthermore, counting external lines (on the valve) always lead to an overestimation of age and thus an underestimation of annual growth rates. Therefore, an analysis of the cross-section of the valve seems necessary to accurately estimate age and growth rate in this species. This aspect should be taken into account in studies of growth and population dynamics.

To evaluate the role of the razor clam Ensis directus in Dutch coastal waters, assessment and understanding its population dynamics is important. As such, the age structure of the population forms a key parameter. Accurate age determination in bivalve shells is not always straightforward due to the difficulty of interpreting externally visible growth lines. In the present paper, we aimed at validating the seasonality in growth line formation using visual techniques in combination with stable oxygen and carbon isotope analyses (δ18O and δ13C). High δ18O values in the shell coincided with growth marks on the external surface of the valve and in acetate peels of the shell's cross section. Most shell δ18O samples were assigned to the months June to September. From November to March no samples were retrieved indicating that the shell did not grow. The lowest reconstructed temperature (6.1 °C) suggests that ~6 °C may be the threshold temperature for growth. Nevertheless, most of the reconstructed values fell above 14.5 °C indicating growth occurred mainly in the summer at relatively high temperatures. Shell δ13C profiles followed a more or less seasonal cycle but no direct relationship could be made between δ13C values and annual growth lines. Although counting external annual growth lines led to a correct estimation of age and consequently of growth rates, we recommend analysing acetate peels of cross-sections to support the distinction between annual lines and disturbance lines.

Growth and reproductive investment of cultured Pacific oysters Crassostrea gigas were studied in two south-western European estuaries: the Ria de Ribadeo in Spain and the Ria Formosa in Portugal. Developing gonads were found in individuals >23.5 mm shell length in the Ria Formosa and >27.5 mm shell length in the Ria de Ribadeo. Although the amount of gonadal mass in relation to total body mass was higher in the Ria de Ribadeo, oysters from this location did not spawn completely. In contrast, oysters from the Ria Formosa completely emptied their gonad during spawning. Reproduction and, consequently, the maximum potential for population expansion may be constrained in both areas: in the Ria de Ribadeo due to suboptimal spawning threshold temperatures and in the Ria Formosa due to higher metabolic costs caused by warmer winter temperatures. Nevertheless, in comparison to northern oyster populations, Portuguese and Spanish populations have higher reproductive output. If suitable environmental conditions are met, expansion of Portuguese and Spanish populations will most likely occur. In the Ria Formosa, where environmental conditions for growth and reproduction are favourable, wild oysters are already observed. In order to follow the dynamics of oyster populations and predict possible negative effects on the ecosystems, it is important to continue monitoring the physiological performance of C. gigas in these areas.

Growth studies based on population-based growth estimates are limited by the fact that they do not take into account differences in age/size structure within the population. To overcome these problems, otolith microstructure analysis is often used to estimate individual growth. Here, we analyse growth of 0-group plaice in the western Wadden Sea in two years: a year preceded by a mild winter (1995) and a year preceded by a severe winter (1996). Growth was analysed by combining information on individual growth based on otolith analysis with predictions of maximum growth (= under optimal food conditions) based on a Dynamic Energy Budget model. Otolith analysis revealed that settlement occurred earlier in 1995 than in 1996. In both years, one main cohort was found, followed by a group of late settlers. No differences in mean length-at-age were found between these groups. DEB modelling suggested that growth was not maximal during the whole growing season: realized growth (the fraction of maximum growth realized by 0-group plaice) declined in the summer, although this decline was relatively small. In addition, late settling individuals exhibited lower realized growth than individuals from the main cohort. This study confirms that growth conditions for 0-group plaice are not optimal and that a growth reduction occurs in summer, as suggested in previous studies.

Unknowingly lumping cryptic species in biological monitoring studies hinders progress in understanding their functioning in a wide range of research fields including population dynamics, ecophysiology and community ecology. The common polychaete worm Scoloplos cf. armiger is a cryptic species complex comprising entirely different developmental modes: holobenthic and pelago-benthic development. In the northeast Atlantic, three putative species have been described on the basis of molecular data and a breeding study. We report on the development of a fast genotyping assay and on the occurrence and distribution of different molecular types in the western Wadden Sea. The genotyping assay consists of PCR-RFLP analysis by two enzymes of a mitochondrial ( cox3-trnQ-nad6 ) DNA segment. A new, fourth type was observed and this was the only type whose geographical distribution was not uniform but instead skewed toward the eastern part of the study area. All three hitherto known types were also observed and these three displayed a significant difference in depth distribution within the study area. This is the first ecological difference reported for the ‘Subtidal Clade’ (SC) versus the ‘Type Locality Clade’ (TLC). The new type (‘Intertidal Clade 2’) had a similar distribution to what is known as the Intertidal Clade (IC). However, the most striking observation is the large degree of overlap between the depth distributions in the western Wadden Sea, where the clade names ‘Intertidal’ and ‘Subtidal’ do not necessarily reflect local species composition. The necessity to genotype Scoloplos cf. armiger in monitoring programs is emphasized.

Monthly investment in soma and gonads in the bivalve Scrobicularia plana is described for three populations along its distributional range: Minho estuary, Portugal; Westerschelde estuary, The Netherlands and Buvika estuary, Norway. Seasonal cycles in body mass (BMI), somatic mass (SMI) and gonadal mass (GMI) indices were observed for all populations. In Portugal, BMI and SMI peaked in mid-autumn, while in The Netherlands both indices were at their highest in mid-spring. Norway showed a different pattern with two distinct peaks: one in mid-autumn and a second peak in spring. GMI reached maximum values in July in Portugal and Netherlands and in June in Norway. Overall, mean BMI and SMI were lower in Portugal while mean GMI was lower in Norway. The spawning period lasted the whole summer in Portugal, but was shorter (only two months) in The Netherlands and Norway. The reproductive investment in The Netherlands was significantly higher than in Portugal and Norway, with the lowest values being observed in Norway. Differences in annual cycles between populations were attributed to environmental factors, namely temperature and food availability. Temperature seems important in shaping the reproductive pattern with more northern populations showing shorter reproductive periods starting later in the year, and a lower reproductive output. In addition, winter water temperatures can explain the lower mean body and somatic mass values observed in Portugal. Food availability influenced the physiological performance of the species with peaks in somatic mass coinciding with phytoplankton blooms. This relation between physiological performance and environmental factors influences S. plana distribution, densities and even survival, with natural consequences on its commercial importance.

Long-term trends in brown shrimp Crangon crangon abundance were studied near the entrance of the Dutch Wadden Sea using a 34 yr time series of fyke net catches. A general trend of increasing abundance was observed. In autumn, brown shrimp abundance was 5 times greater than in spring, and interannual fluctuations were also more pronounced. Biotic and abiotic conditions showed effects with time lags of up to 1 yr, which is consistent with the species' life cycle. The popu- lation responded rapidly to changes in environmental conditions: abrupt declines after adverse con- ditions, as in spring 1999, were followed by steep recoveries in the following autumn. Two hypothe- ses were tested and discussed: (1) autumn recruitment is related to predator abundance and temperature during previous warmer seasons, and (2) overwintering adult abundance is determined by predation pressure and abiotic conditions in winter. In general, predator abundance was the main factor correlated to brown shrimp abundance, especially in autumn. Multiple linear regression mod- elling showed that predators altogether accounted for up to 55% in spring and up to 85% in autumn of the explained variance. Previous winter conditions such as sunshine duration, salinity and fresh water discharge, and the North Atlantic Oscillation Index (NAOI) were also correlated with autumn abundance. Yet, temperature conditions during the previous growing season did not determine the autumn stock size. Winter sunshine duration and the winter NAOI were correlated with spring stock size. Additionally, temperature and salinity were relevant factors affecting abundance during spring. A significant positive relationship between spring and autumn abundance and annual commercial landings was also found.

The American razor clam Ensis americanus is a marine bivalve indigenous from the American coast that was introduced in Europe in the late 1970s and has managed to build up strong populations along the European coast. In the present paper, we studied energy investment into soma and gonads by following the seasonality in growth and reproduction of this species in a subtidal area of the western Dutch Wadden Sea. Body and somatic mass indices showed a seasonal pattern with maximal values in August and minimal in April. Gonadal mass index showed the opposite trend with highest values in April. Spawning started in April/May and a second, but weaker, spawning event apparently occurred in August/September. Gonadosomatic ratio values were very low. Just before the spawning period, only 2.5% of the body mass of E. americanus consisted of gonads.

Cerastoderma edule and Mya arenaria are two common bivalve species in European waters. Longevity and maximum size are much greater in the latter species. Because comparison of species life-history strategies states that a long life span (i.e. high annual survival) generally goes with lower fecundity, we hypothesise that reproductive output would be lower in M. arenaria than in C. edule. In the present paper, we studied the reproductive strategies of these two species in an intertidal and a subtidal area of the western Dutch Wadden Sea, by following seasonal changes in absolute and relative weights of somatic and gonadal tissues in these bivalves. Starting of spawning was similar in the two species, around May, except for intertidal M. arenaria, which initiated spawning in August. Individual energy investment in reproduction was similar for the two species but, unlike M. arenaria, C. edule spawned completely, releasing all energy of gonadal mass in the form of gametes. Mya arenaria used the gonad not only for reproduction but also for storage. In the intertidal area, we found a trade-off between longevity and reproduction, i.e. maximum reproductive output (expressed as a proportion of body mass) was higher in C. edule than in M. arenaria. However, since body size is larger and life span longer in M. arenaria than in C. edule, mean lifetime reproductive output per individual must be higher in the first than in the latter. Based on the differences in reproductive strategies of these two species, we hypothesise that the negative effects of warming climate on bivalve population dynamics in the Wadden Sea will be stronger in C. edule than in M. arenaria.

In the present study, various body size scaling relationships describing the physiological performance of plaice Pleuronectes platessa (L.) were derived using a dynamic energy budget (DEB) model and compared with allometric relationships derived from a static energy budget (SEB) model. Results indicated that DEB models can correctly predict the physiological performance of plaice within variable environments. Dynamic energy budgets are preferred over static energy budgets because they are not descriptive but based on first principles, they are not species-specific, and they can be used for extrapolations beyond the range of experimental data. Nevertheless, some aspects of the DEB model can still be improved. These include: [1] processes underlying the temperature tolerance range, temperature acclimation and the relationship between optimal temperature and body size; [2] the contribution of various processes to metabolism; and [3] the incorporation and quantification of Fry's scheme of the environment, especially of masking factors (e.g., sub-optimal salinity conditions which load the minimum metabolism) and limiting factors (e.g., low oxygen conditions that constrain the maximum metabolic rate). These improvements would offer a wide range of opportunities for further application, such as the reconstruction of food and growth conditions; the validation of age determination by means of otolith readings; the analysis of intraspecific genetic variability versus non-genetic phenotypic adaptations; and the interspecific comparison of energy flows by means of variability in the various DEB model parameters.

The musselMytilus edulis is an abundant bivalve in the Dutch Wadden Sea, both in intertidal areas as well as in subtidal culture plots. From mid 1980’s to late 1990’s, strong declines in mussel intertidal populations have been observed, both in terms of occupied area and in biomass. Despite the efforts since 1999 to preserve intertidal mussel beds, abundance and biomass of mussels in the Dutch Wadden Sea are at present still much lower than in the 1970’1s. In the present paper, we tested whether reproductive failure could have been the cause for the low recruitment ofM. edulis in the western Dutch Wadden Sea. Water temperature is an important factor influencing growth and reproduction in bivalves. The observed increase in mean temperature in the Dutch Wadden Sea during the last decades suggests that an effect of temperature on the population dynamics of mussels might be expected. Nevertheless, no significant relationship was found between body condition and mean winter temperature. Therefore, a decrease in body condition and, consequently, in reproductive output, due to increasing temperature, will not have been a cause for the observed low recruitment in recent years. The seasonal patterns of individual growth supported this view: most adults developed gonads during the spawning season suggesting that reproductive (gametogenic) failure was not a cause for the low recruitment. Nevertheless, reproductive investment by the mussel population studied was not optimal since complete spawning hardly occurred. In addition, the high gonadosomatic ratio at the end of the summer did not result in heavy spawning, suggesting resorption of gonadal tissue due to unfavourable environmental conditions (too high temperature and/or food limitation during summer). Reduced recruitment could be due to poor spawning but other factors that exert their influence after spawning (predation on larvae or postlarvae, lack of settlement substrate) or on the adult population (decrease in number of spawners) are also likely to be involved in the observed low recruitment during the last years.

In estuarine areas, bivalve species can be found in a variety of environments, where they experience large differences in environmental conditions. In the present paper, the importance of different habitats (intertidal, subtidal and adjacent coastal waters) for the persistence of the population was evaluated for the bivalve Macoma balthica (L.) in the western Dutch Wadden Sea estuary. Intra-specific variation in growth and reproductive output were followed during the year and related to local abiotic conditions. Significant differences in growth and reproductive investment were found between locations. Young individuals were mostly found in the intertidal area, where growth in terms of somatic mass was good. These areas were not favourable for adult individuals, since growth in shell length was low and many individuals did not reproduce. In the subtidal, where the highest densities were found, somatic and gonadal mass indices were low. Coastal areas had the lowest densities and showed high growth in terms of shell length and body mass. The habitat with the highest reproductive effort per individual was not the most important habitat in terms of reproductive output due to differences in density and in size of the habitat type. For M. balthica, the subtidal habitat contributed the most to the reproductive output of the western Dutch Wadden Sea population although the highest reproductive output per individual was in the coastal area.

The Pacific oyster Crassostrea gigas was introduced in Europe for commercial purposes in the mid 1960s. It was initially thought that low winter temperatures would restrain this species' reproduction and settlement; however, its present distribution in areas where no introduction has taken place suggests that natural invasion and expansion has occurred. Along the European coast, wild populations of Pacific oysters are already found from northern Germany to southern Portugal. Whether C. gigas will continue to further expand through northern waters will depend on its physiological performance. In this study, the performance of wild oyster populations has been studied in terms of growth and reproduction at three stations: La Rochelle (France; 46°N), Yerseke (Oosterschelde estuary, The Netherlands, 51°N), and Texel (Wadden Sea estuary, The Netherlands, 53°N). The French population had the lowest somatic-shell mass ratio and an increase in maximum shell length, somatic and gonadal mass was observed from France to the Netherlands. In addition, mean oocyte diameter decreased significantly from south to north. The combination of increasing gonadal mass and decreasing oocyte volume suggests an increasing reproductive output in terms of egg numbers from France to The Netherlands. Differences in temperature between locations will at least be partly responsible for the observed patterns; however, other environmental factors (such as food availability, predation pressure, sediment type and/or seston concentration) cannot be excluded. Since smaller eggs (oocytes) are thought to have a longer development time, the environmental conditions along the Dutch coast may result in increased larval dispersal and possibly in further population expansion.

The bivalve Spisula subtruncata is usually abundant in shallow coastal waters along the Dutch coast. However, its biomass has been decreasing since 1995. In order to assess whether reproductive failure may be the cause of the observed decline over the last decades, the energy investment in reproduction of a population of S. subtruncata from central Dutch coastal waters was studied. The population studied consisted of individuals of up to four years old. Shell length reached maximum values of around 32 mm and individual total body, somatic and gonadal ash-free dry mass reached maximum values of about 278 mg AFDM, 252 mg AFDM and 76 mg AFDM, respectively. A clear seasonal cycle in somatic and gonadal mass was observed. Somatic and gonadal mass indices increased in early spring and reached maximum values during summer, followed by a decrease to minimum values at the beginning of the following year. Spawning was in June–July and settlement of spat seems to have occurred in July–August. Mean oocyte diameter was 57.43 ± 0.03 μm, corresponding to a volume of 98972 μm3. These results suggested that reproductive failure was not the cause of the current population decline. Most likely, unsuccessful settlement of spat and/or severe predation during the first months of life were responsible for the observed patterns.

Dynamic energy budgets are used for the description of the energy flow through individual organisms from the assimilation of food to the utilisation for maintenance, growth, development and reproduction. In this paper, a procedure for estimation of the parameters of Kooijman's Dynamic Energy Budget (DEB) model is introduced and subsequently parameters are estimated for the following Northeast Atlantic bivalve species: the Baltic clam Macoma balthica (L.), the sandgaper Mya arenaria L., the cockle Cerastoderma edule (L.), the blue mussel Mytilus edulis L. and the Pacifc oyster Crassostrea gigas (Thunberg, 1793). For none of the species, a complete set of parameters could be compiled. A special protocol was developed to account for missing values and to achieve consistency between parameters. Species were similar in their optimal temperature range, as reflected in a common Arrhenius temperature of 5800 K, which corresponds with a Q 10 of 2. Differences between species were observed in width of the optimal temperature range. The taxonomic relatedness between species was reflected in similar volume-specific maintenance costs, costs for growth and almost similar maximum storage density of energy. Species differed in their maximum surface area-specific assimilation rate by a factor of 6 and in the fraction of energy allocated to reproduction (ranging from 0.15 to 0.50). These differences are reflected in the maximum theoretical total shell length of the species, which varied from about 3 cm in M. balthica, 6 cm in C. edule, 15 cm in M. arenaria and M. edulis and 45 cm in C. gigas .

The energy flow in various bivalve species (Macoma balthica, Mya arenaria, Cerastoderma edule, Mytilus edulis and Crassostrea gigas) in different habitats (intertidal, subtidal and offshore areas) of Dutch coastal waters was analysed by comparing growth observations in the field with model simulations by means of the Dynamic Energy Budget (DEB) theory. The reconstruction of the seasonal food conditions suggested that with respect to food consumption, M. balthica and C. edule are the most successful species, followed by M. arenaria, and M. edulis and C. gigas. Positive growth was correlated with the beginning of the spring bloom in primary production and food limitation between species was lowest during this period. After the spring bloom, severe food limitation during the summer period was found. As a result, negative body growth occurred during most of year. DEB model simulations both on an annual and a seasonal basis also showed that, at the prevailing water temperatures, growth of the different species was not maximal. It remains uncertain whether the suboptimal food conditions were the consequence of food limitation or also of reduced filtration efficiency due to the high sediment load in the water.

In this paper, we apply the Dynamic Energy Budget (DEB) theory to bivalve species (1) to provide basic body-size scaling relationships that can be used to predict species characteristics when basic information is lacking, and (2) to analyse the discrepancy between DEB predictions based on energetic constraints and field observations, in order to identify potentially important factors in life history strategy of bivalves. Body-size scaling relationships were identified for size at first reproduction, Von Bertalanffy growth parameter, and egg and larval development time in relation to egg and larval volume and temperature conditions. Due to their small egg volume, bivalve species are characterised by a relatively short pelagic larval stage. The main discrepancy between field observations and DEB predictions was in the relationship between egg and larval volume and adult body volume. In bivalves, the characteristics of the early life stages are not related to body size of the species. Since the minimum size of settling larvae is always larger than 125 μm, it is suggested that successful settlement might be the key factor. Settlement size or volume of the fragile larvae must be in balance with the sediment composition, i.e. similar to or larger than that of the sediment grain size. © 2006 Elsevier B.V. All rights reserved.

We analysed the diversity and abundance of ammonia-oxidizing Archaea (AOA) and Bacteria (AOB) in the shallow warm-water sponge Halisarca caerulea and the deep cold-water sponges Higginsia thielei and Nodastrella nodastrella. The abundance of AOA and AOB was analysed using catalyzed reporter deposition-fluorescence in situ hybridization and (real-time) quantitative PCR (Q-PCR) targeting archaeal and bacterial amoA genes. Archaeal abundance was similar between sponge species, while bacterial abundance was higher in H. caerulea than in N. nodastrella and H. thielei. Q-PCR showed that AOA outnumbered AOB by a factor of 2 to 35, suggesting a larger role of AOA than of AOB in ammonia oxidation in sponges. PCR-denaturing gradient gel electrophoresis was performed to analyse the taxonomic affiliation of the microbial community associated with these sponges. Archaeal and bacterial amoA genes were found in all 3 sponges. The structure of the phylogenetic trees in relation to temperature and sponge species was analysed using all published amoA sequences retrieved from sponges. Temperature was an important factor influencing the distribution of nitrifiers in sponges. Both archaeal and bacterial amoA sponge sequences tended to cluster with sequences retrieved from habitats of similar temperature. This is the first time that similarity in AOB diversity is described between distantly related species (H. thielei belonging to the class Demospongiae, and N. nodastrella to Hexactinellida). The results described here support the idea of a relatively uniform microbial community between distantly related sponges and suggest that temperature (rather than phylogenetic distance) is determining the diversity of AOA and AOB in sponges.

This study analyzed the isotopic profiles of four aragonitic shells of Scrobicularia plana in conjunction with measured seawater temperatures and salinities. Comparison of delta O-18(SHELL) with expected values revealed fractionation of delta O-18 in near equilibrium with the ambient environment. Growth cessation occurred between November and March. Carbonate deposition stopped when temperatures were >12 degrees C. Analysis of delta C-13(SHELL) values suggested that carbon in the shell does not reflect the DIC in ambient water, likely due to the incorporation of metabolic carbon. An ontogenetic trend of increasing delta C-13 values over time was observed, likely related to changes in metabolic activity. Annual growth patterns were inferred from delta O-18(SHELL) profiles and compared with internal and external growth lines. Estimations of age based on external lines were unreliable, resulting in overestimation of age and underestimation of growth rates, likely due to the disturbance lines being wrongly identified as annual. Analysis of internal lines may lead to over-or underestimation of age and was more reliable in recent portions of the shell.

Temperature tolerance and sensitivity were examined for some North Atlantic marine species and linked to their energetics in terms of species-specific parameters described by dynamic energy budget (DEB) theory. There was a general lack of basic information on temperature tolerance and sensitivity for many species. Available data indicated that the ranges in tolerable temperatures were positively related to optimal growth temperatures. However, no clear relationships with temperature sensitivity were established and no clear differences between pelagic and demersal species were observed. The analysis was complicated by the fact that for pelagic species, experimental data were completely absent and even for well-studied species, information was incomplete and sometimes contradictory. Nevertheless, differences in life-history strategies were clearly reflected in parameter differences between related species. Two approaches were used in the estimation of DEB parameters: one based on the assumption that reserve hardly contributes to physical volume; the other does not make this assumption, but relies on body-size scaling relationships, using parameter values of a generalized animal as pseudo-data. Temperature tolerance and sensitivity seemed to be linked with the energetics of a species. In terms of growth, relatively high temperature optima, sensitivity and/or tolerance were related to lower relative assimilation rates as well as lower maintenance costs. Making the step from limited observations to underlying mechanisms is complicated and extrapolations should be carefully interpreted. Special attention should be devoted to the estimation of parameters using body-size scaling relationships predicted by the DEB theory.

Required assimilated energy to support observed growth was reconstructed for four common bivalve species (Mya arenaria, Cerastoderma edule, Mytilus edulis and Macoma balthica) from various Northeast Atlantic coastal areas, along the species distributional range. The approach applied was based on the Dynamic Energy Budget (DEB) theory whereby observed growth patterns in the field, in combination with prevailing temperatures, were used to reconstruct the average food intake experienced in the field scaled to the maximum possible. For all species, results suggest food limitation over the range of locations. In general, reconstructed food intake indicated better conditions for C. edule compared to the other species, while M. edulis presented the lowest food conditions in all the areas. Despite the indications for a latitudinal trend in primary production, no clear pattern or relationship between reconstructed food conditions and latitude was observed suggesting that any trend may be overruled by local conditions. © 2009 Elsevier B.V. All rights reserved.