bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal Patterns of Dark Carbon Incorporation by Natural Phytoplankton Assemblages in the Central Cantabrian Sea (Bay of Biscay)
Authors: Fernanáez Emilio , Bode Antonio 
Published: May 2008

Abstract. Phytoplankton dark carbon incorporation rates measured in the Central Cantabrian Sea (Bay of Biscay) exhibited a clear seasonal pattern. The highest rates were measured in May and September, whereas during winter very low rates were observed. Step‐wise regression analyses were performed with temperature, chlorophyll and the production/chlorophyll ratio as independent variables. The production/chlorophyll ratio was the most significant contributor (29.02%) on a yearly basis. Chlorophyll also explained a relevant percentage of dark carbon incorporation variability (15.36%), whereas temperature accounted for less than 0.5% of variance. Very similar results were obtained when mixing and stratification periods were analysed separately. The ratio between dark and light carbon incorporation showed high values (22–30 %) in January and March at all stations. During late spring and summer this ratio was low, ranging from 4 to 10 %. These results indicate a linkage between dark and light carbon incorporation and, therefore, that the subtraction of dark bottle counts could lead to underestimations of actual primary production rates, especially during low‐production periods.SummaryCarbon incorporation rates integrated over the water column varied from less than 4 to more than 7 mg C · m‐2· h‐1, showing a marked seasonal pattern in close phase with the production/chlorophyll ratio. The highest rates were recorded in May and September at all stations. Verly low rates were measured in winter. Step‐wise regression analysis performed on the data revealed that the production/chlorophyll ratio explained the highest percentage of dark carbon incorporation variability (29.02%) on a yearly basis. The chlorophyll a concentration was also a relevant contributor (15.36%), whereas temperature explained less than 0.5 % of the variance. The percentage of dark to light carbon incorporation exhibited a clear seasonal variation. The highest percentages were measured in January and March. This ratio remained between 4 and 10.3% during late spring and summer.
Ecology of the Symbiotic Coral Cladocora caespitosa (L.) (Faviidae, Scleractinia) in the Bay of Piran (Adriatic Sea): II. Energy Budget
Authors: Schiller Christian 
Published: May 2008

Abstract. The temperate, symbiotic coral Cladocora caespitosa occurs naturally with variable numbers of zooxanthellae. This allows us to study differences in the physiology of symbiotic and “non‐symbiotic” polyps and to correlate them with zooxanthellae activities.Zooxanthellae density in “dark” (normal‐colored) polyps was 50 times higher than in “white” (bleached) polyps.The chlorophyll a content per zooxanthella was 3 times, and Chi c was 13 times higher in white polyps than in dark ones. O2‐flux experiments were conducted with colonies in situ and with single polyps ‐ dark and white ‐ under laboratory conditions. Two approaches were used to evaluate the contribution of zooxanthellae translocation products to animal respiration. Both revealed that the animal tissues derive a higher benefit from the zooxanthellae during periods of low water temperature than during warm periods.
Plankton Distribution Patterns in a Mediterranean Dilution Basin: Amvrakikos Gulf (Ionian Sea, Greece)
Authors: Panayotidis P. , Pancucci M. A. , Balopoulos E. , Gotsis‐Skretas O. 
Published: May 2008

Abstract. The present work describes Amvrakikos Gulf (Ionian Sea, Greece) as a dilution basin and provides information concerning the relationships between the hydrology and plankton composition and distribution.Amvrakikos Gulf is characterized by a differentiated planktonic system which is apparently directly influenced by the input of the rivers located at the northern part of the gulf.
Local Distribution and Seasonal Variation of Fe, Pb, Zn, Cu, Cd, Na, K, Ca, and Mg Concentrations in the Seagrass Cymodocea nodosa (ucria) Aschers. in the Antikyra Gulf, Greece
Authors: Malea P. , Haritonidis S. 
Published: May 2008

Abstract. The local distribution and seasonal variation of Fe, Pb. Zn, Cu. Cd, Na. K, Ca, and Mg concentrations in Cymodocea nodosa (ucria) Aschers., one of the most abundant seagrasses of the area. as well as their concentrations in the sediment and seawater were studied in the Gulf of Antikyra (Greece). The gulf is characterized by a bauxitic substrate and waste discharges from an aluminiumproducing factory. Many of the metals investigated constitute components of the two above‐mentioned metal sources.The mean metal concentrations (± SE) in the seagrass decreased in the order: Ca > Na > K > Mg > Fe > Pb > Zn > Cd > Cu.At the sampling stations A1, A2, A3, B3, and C1, where sufficient data was available for statistical analysis. the concentrations of metals in the plant did not vary significantly among stations (P > 0.05).Metal concentrations in C. nodosa revealed two patterns of significant seasonal variation. The first pattern involved Fe, Cd, Na. and Ca and was characterized by high mean concentrations in summer and autumn. A reverse pattern was shown by Pb, Cu. and Mg. These patterns are discussed in relation to the growth dynamics. and leafage of the seagrass. the metal concentrations in the environment. the intermetal correlation, etc.Cu, Cd, Pb, and Ca concentrations in the seagrass were significantly correlated with those in the sediment, whereas a direct relation of plant and seawater concentrations was obtained only for Ca and Mg. The intermetal correlation matrices in C. nodosa showed synergistic interactions between Cd‐Ca, Pb‐Mg, Fe‐Ca, Cu‐Pb, Na‐K, and Na‐Ca and antagonistic interactions between Cd‐Pb, Cd‐Mg, and Pb‐Ca.The Cu, Cd, and Pb concentrations and the maximum Fe concentration in C. nodosa in the Antikyra Gulf are high compared with species belonging to the Cymodorroideae subfamily from other geographical areas.SummaryFe, Cu, Pb, Cd, Ca, Na, and Mg concentrations in C. nodosa displayed significant seasonal variation. The mean concentrations of Fe, Cd, Na, and Ca were high in summer and autumn. In contrast, Pb, Cu, and Mg concentrations were high in December and March. The concentrations of Fe, Cu, Zn, Cd, Pb, Na, K, Ca, and Mg did not vary significantly among the stations A1, A2, A3, B3, and C1 of Antikyra Gulf (Greece). Significant correlations were obtained between Ca and Mg concentrations in the seagrass and seawater and between Cu, Cd, Pb, and Ca concentrations in the plant and the sediment. Cd‐Ca, Pb‐Mg, Fe‐Ca, Cu‐Pb, Na‐K, and Na‐Ca showed positive correlations, whereas Cd‐Pb, Cd‐Mg, and Pb‐Ca showed negative correlations in the plant. Finally, the mean metal concentrations in C. nodosa decreased in the order: Ca > Na > K > Mg > Fe > Pb > Zn > Cd > Cu.The concentrations of the heavy metals Cu, Cd, and Pb in C. nodosu in the study area are high compared with species belonging to the Cymodoceoideae subfamily from other areas.
A δ13C Study of the Feeding Habits in Four Mediterranean Leptomysis species (Crustacea: Mysidacea)
Authors: Dauby P. A. 
Published: May 2008

Abstract. Mediterranean Leptomysis species are bentho‐nectonic shrimps living close to seagrass bed bottoms, forming swarms during the day and feeding on detritus and sedimentary organic matter during the night. As this matter is derived from different plant sources (phytoplankton, seagrasses, macro‐ and microalgae), assimilated carbon entering mysid tissues can hardly be identified on the basis of digestive tract analyses. Stable carbon isotope ratio measurements help to delineate food sources of the different studied Leptomysis species because plants are distinct isotopically. These 6°C measurements reinforce the view of the minor role of seagrass carbon in benthic food webs and of the importance of algae in the dynamics of these ecosystems.SummaryFour Leptomysis species inhabit three relatively closely adjoining biotopes in the Gulf of Calvi: L. lingvura near the surface, forming shoals within rock blocks, L. posidoniae in Posidonia seagrass beds, and the couple L. heterophila +L. gracilis at the lower border of the infralittoral zone. These three biotopes are characterized by different main plant food sources (namely macroalgae, seagrasses, and phy‐toplankton), which are C isotopically well separated. δ13C measurements of the different Leptomysis populations show that these shrimps do not feed preferentially on the carbon source prevailing in their own biotope, but rather have an isotope ratio (‐16.5 to ‐20%0) close to the algal ratio. These observations can either be explained by feeding selectivity or by a differential assimilation rate of ingested material; in any case, they corroborate the role of algae in the trophodynamics of Mediterranean seagrass ecosystems.
Trophic Structure and Community Composition of Polychaetes Inhabiting Some Sabellaria alveolata (L.) Reefs Along the Valencia Gulf Coast, Western Mediterranean
Authors: Porras R. , Bataller J. V. , Murgui E. , Torregrosa M. T. 
Published: May 2008

Abstract. A total of 24 samples from Sabellaria alveolata reefs have been collected and subjected to cluster analysis using the trophic dominance of each feeding guild as grouping variables. The result is the arrangement of samples by colony physical structure and S. alveolata dominance.Relating cluster groups to reef development phases reveals an inverse relationship between reef growth and the organization of the associated polychaete taxocoenosis. During the growth phase of the reef, S. alveolata dominates the community, excluding other taxa from colonization. Growth is followed by the destruction phase. Negative physical and biological factors for reef enlargement may open patches on the reef surface, allowing recruitment of other species and colony erosion. The end of this phase is represented by eroded reefs with high structural complexity and high species richness.Summary Sabellaria alveolata reefs reported from 13 localities in the study area have been classified according to their structural features into two main types: a) developed reefs, with considerable volume and a shape independent of the underlying substrate and b) eroded reefs, which form tiny encrusting plates covering the substrate. Based on cluster analysis each one of these may be subdivided according to SAQD values.
The Brittlestar Amphiodia urtica; A Candidate Bioindicator?
Authors: Maurer D. , Nguyen H. 
Published: May 2008

Abstract. The ophiuroid Amphiiodia urtica Lyman is presently under study as a potential wastewater discharge indicator species from ocean outfalls in the Southern California Bight. On the San Pedro Shelf, the maximum abundance of A. urtica was found at depths from 30 to 100 m, and in sediment with a median grain size of 0.085 nim, 60–80% sand. 15–30% silt, 0–37% clay, and 0.2–0.5% TOC. The mean abundance of A. urtica fluctuated annually with a slight increase from 1977 through 1993.The hypothesis was posed that the distribution and abundance of A. urtica is not influenced by an ocean outfall and its operation on the San Pedro Shelf. Based on long‐term (1977–1994) and intensive (2860 samples) sampling. the hypothesis was rejected. However, the effect of the outfall is not clear because sediment bioassays from test stations and controls produced no significant differences in survivorship and growth of juveniles. Amphiodia presently occupies areas within the Zone of Initial Dilution (ZID) where it was not found during the mid‐1970s and early 1980s. While recognizing that A. urtica abundance responds to proximity to the outfall, the mechanism for this response is still unclear. The application of a single species as a bioindicator is not recommended, and most certainly not without fully essing its role in community structure and function.
The Influence of the Cockle, Cerastoderma edule, on the Macrozoobenthic Community of Tidal Flats in the Wadden Sea
Authors: Flach Els C. 
Published: May 2008

Abstract. The cockle Cerastoderma edule is one of the large and important species of the tidal flats of the Wadden Sea. C. edule disturbs the upper sediment layer due to its crawling and “shaking” behaviour. About 7% of a cockle population move within one week. The mean distance of movement is ‐4 cm per week, which, in the case of a 2‐year‐old cockle with a length of ˜3 cm, means that ˜20 cm2 of sediment is disturbed to a depth of ˜3 cm. Besides these measurable movements, cockles also regularly “shake” themselves, thereby disturbing the sediment around them to at least ˜0.5 cm. At a density of 500 cockles per m2 of a mean length of 3 cm, ˜16% of the sediment surface is occupied by cockles and another ˜29% is disturbed by cockles within one week.To study the effects of cockles on recruitment of other benthic species, densities of 0, 125, 250, 375 and 500 cockles (mean length 3 or 3.5 cm) were added to 1‐m2 plots within large depopulated squares in April. Subsequently, sediment samples were sieved once a month (from June to September) and the densities of all macrozoobenthic species were estimated. The presence of cockles significantly reduced the densities of juveniles of the bivalve species C. edule, Macoma balthica, Mya arenaria, Tellina (Angulus) tenuis, and Ensis directus and of the worm species Pygospio elegans, Lanice conchilega, Eteone longa, Anaitides spec., Nephtys hombergii, Heteromastus filiformis, Scoloplos armiger, and Tharyx marioni and of the amphipods Corophium volutator and C. arenarium. Non‐significant effects were found only in Capitella capitata and Nereis diversicolor. For all species mentioned above a negative effect was already observed at the lower cockle densities of 125 ‐ 250 per m2. Reductions of about 50% or more were found at densities of 500 per m2, which was more than could be expected based on the area occupied by the cockles (˜16%), but close to the area occupied plus disturbed (˜45%). It is concluded that (dense) assemblages of adult cockles can have a strong influence on the macrozoobenthic community.
Meiobenthic Organisms as Indicators of Mixing Processes in the Baltic Surface Sediments*
Authors: Pempkowiak Janusz , Kozuch Joanna , Szymelfenig Maria 
Published: May 2008

Abstract. Two sediment cores were collected in the southern Baltic Sea and sliced into 1.0cm‐thick layers. Sediments of each layer were analysed for activities of 210Pb, 137Cs, 134Cs and for the density of meiobenthic organisms (meiofauna).Zones with the rapid mixing occur in the uppermost layers (0–3 cm) of the cores based on I34Cs profiles. The extent and density of meiofauna confirmed the rapid mixing and revealed layers with slow mixing (4–8 cm). Sedimentation rates were derived from 210Pb profiles below the mixing zones (1.21 and 1.72 mm a‐I) and were confumed by 137Cs distribution. Of twenty‐one major meiofauna taxa commonly found in the Baltic sediments, three were present in the cores.
The Effect of the Introduction of the American Species Marenzelleria viridis (Polychaeta; Spionidae) on the Benthic Ecosystem of Vistula Lagoon
Authors: ŻMudziński Ludwik 
Published: May 2008

Abstract. In the late 1980s, a radical change in the macrozoobenthos composition occurred in the Vistula Lagoon, an oligohaline and silted water basin. This structural change is a result of the mass appearance of the very strongly euryhaline spionid polychaete Marenzelleria viridis Verrill, a newcomer from North American estuaries. It considerably reduced the previous bottom macrofauna, which was composed mainly of Chironornidae larvae and oligochaetes.The penetration depth of the macrozoobenthos into the sediments and its total biomass increased in the last years, which enhanced the organic matter displacement in sediment layers of a greater thickness. The previous bottom dwellers inhabited mainly the most superficial sediment layer, whereas the new polychaete immigrant can penetrate down to a depth of 20–40 cm.
Episodic Mass Invasions of Juvenile Gadoids into the Wadden Sea and their Consequences for the Population Dynamics of Brown Shrimp (Crangon crangon)
Authors: Berghahn Rüdiger 
Published: May 2008

Abstract. The brown shrimp Crangon crungon is considered to be a key species in the coastal waters of the North Sea and in particular in the Wadden Sea, since it occurs in masses and acts as both a highly efficient predator and important prey. The Wadden Sea is the nursery ground for brown shrimp. In 1990, a mass invasion of O‐group whiting (Merlangius merlangus) reduced Crangon numbers to almost zero. Similar events, which had previously been reported in the 19th century, were observed in 1959 (whiting), 1970 (cod, Gadus morhua), and 1983 (cod and whiting).The 1990 invasion and the decline of the shrimp stock are documented on the basis of surveys that are compared with the years preceding and following. Consequences for the food web in the Wadden Sea and the reasons for the complete recovery of the shrimp stock in each case within one year after its collapse are discussed with regard to the Crangon crungon behaviour and reproductive potential. Sampling error and the impact of fisheries are also considered.
Consequences of the Sudden Removal of Nearly All Mussels and Cockles from the Dutch Wadden Sea
Authors: Beukema J. J. , Cadée G. C. 
Published: May 2008

Abstract. Three successive years of recruitment failure, intensive fishery, and high rates of natural mortality eliminated all intertidal mussel beds and nearly all cockle beds from the Dutch Wadden Sea in the course of 1990. In late 1990 and early 1991, zoobenthic biomass and particularly bivalve stocks were unprecedentedly low. The following unusual events were noted:

Relatively high diatom and chlorophyll concentrations in the autumn of 1990 and an exceptionally early and dense spring bloom of diatoms in March 1991;
Exceptionally early onset of rapid growth in the bivalve Macoma balthica in March 1991;
Above‐average weights of the soft parts of bivalves in the 1990/91 winter;
Elevated mortality rates in bivalves that could serve as alternative prey for birds specialised on big bivalves (oystercatchers and eiders);
Signs of food shortage in such birds: high mortality rates and emigration to other feeding areas;
A rapid recovery of the benthos started in the summer of 1991, accelerated by an exceptionally high recruitment in some of the affected species.

It is concluded that the Wadden Sea ecosystem responded in an elastic way to the removal of two of its key species. The events are not seen as merely coincidental but are regarded as a chain of causes and effects.
Spatial and Temporal Distribution of Oxidation Events Occurring Below the Sediment‐Water Interface
Authors: Forster Stefan 
Published: May 2008

Abstract. Irrigation and bioturbation lead to transport of dissolved oxygen into anoxic sediments. The depthdistribution of local oxygen input and the total time of oxygen presence was measured at randomly sampled locations within anoxic sediments, originating from the North Sea.In the laboratory, continuous redox potential records, displaying a transient increase and decrease when in contact with oxygen for a limited time, were used to record oxidation events'. Oxygen microelectrodes were used to confm the presence of oxygen. Measurements were performed for 180 d at 230 locations in the top 6 cm of sediment cores containing the natural macrofauna community.4783 oxidation events m‐2· d‐1 were recorded within the upper 6 cm of the sediment. The number and duration of oxidation events declined with sediment depth below the oxic zone. Oxygen was present in the anoxic sediment, as determined from redox potential measurements, ≥ 6 h per day at 10% of the randomly chosen locations within the upper 3 cm. The overall distribution of oxidation events and their duration suggest that local, pulsed additions of oxygen by irrigation may be sufficient to maintain an oxidised sediment layer (sensu Jorgensenamp; Revsbech, 1989). Oxic environments along burrow walls rapidly fluctuate between oxic and anoxic conditions. Using oxygen microelectrodes the presence of oxygen (oxic conditions) in these halos was found to range from 2 to 12 h per day. Continuous redox measurements show that oxidised conditions fluctuate with the oxygen pulses and display the same durations, although these may range up to 21 h per day. Oxic and oxidised sediment volumes are estimated to represent < 1% and 3.7%. respectively, of the anoxic sediment to 6 cm depth. Recognition of temporal variability and spatial heterogeneity of sedimentary conditions may prove valuable for future conclusions drawn in other research fields.
The Decline of the North Sea Whelk (Buccinum undatum L.) Between 1970 and 1990: A Natural or a Human‐Induced Event?
Authors: Hallers‐Tjabbes Cat C. Ten , Everaarts Jan M. , Mensink Berend P. , Boon Jan P. 
Published: May 2008

Abstract. Recent surveys in the southern and central North Sea and the Dutch Wadden Sea revealed that the whelk Buccinun undarum L. can no longer be found in areas where whelks were abundant twenty or more years ago.The decline of whelk populations tends to coincide with areas of various, intense human activities, which may cause either pollution or physical damage. Potential causes for the decline of whelks from the southern North Sea and coastal areas are discussed and considered in view of North Sea ecology and protective policies for the North Sea.
The Model‐Free Analysis of Growth Curves
Authors: Aldrich John Carlson , Lawler Ian F. 
Published: May 2008

Abstract.

An incremental (graphical in this presentation) method for the analysis of growth curves has revealed actual, as opposed to modelled, growth rates. Here, we present data derived from the scallop Pecten maximus (L.). These actual rates exhibit differences in annual environmental conditions and differences between local populations.
Both first and second derivatives (growth rate and acceleration ⁄ deceleration in growth rate, respectively) can be obtained from plotted size ⁄ age data: here, size is represented by the height of the flat left valve.
The analysis of age class data from different years allows one to estimate maximum theoretical rates in any given year.
The analysis of individual data naturally reveals more than the analysis of average data, reinforcing the average nature of population growth parameters.
The departure of average data from the maxima revealed by the analysis of growth rate and acceleration allows one to identify changes in environmental conditions in different years.
The Von Bertalanffy growth curve has been used as an example because it is well known and widely used; however, any desired growth curve can be fitted by the method discussed here.
Spectrofluorometric Applications in Studying Macroalgal Exudates*
Authors: Dujmov Jozo , Sučević Perica , Antolić Boris 
Published: May 2008

Abstract. In this paper we present a one‐year investigation on the fluorescence characteristics of released products of selected Adriatic seaweeds. The technique chosen was UV‐fluorescence spectroscopy with the synchronous mode, which involves the stepping of the excitation and emission monochromators. The five species, of representative macrophytes, Cystoseira compressa, Dictyopreris polypodioides, Gracilaria bursapastoris, Pterocladia capillacea, and Ulva rigida, were chosen on the basis of their dominance in the plant communities typical for the area near Split ‐ Central Adriatic. Our results suggest that macroalgal‐related dissolved fluorescent matter can be categorized into two distinct groups of fluorescing compounds with the following excitation wavelengths: one from 320–360 nm, probably for compounds with 2 fused aromatic rings, and another from 360–420 nm, corresponding with 3 & 4 fused rings.The contribution of aromatics with 2 and with 3 & 4 rings was very similar in the brown algae Cysroseira compressa and Dictyopteris polypodioides, while in the red algae Gracilaria bursapastoris and Pterocludia capillacea as well in the green alga Ulva rigida the group with 2 rings dominated.