bluuebunny/crossref_metadata_2025 huggingface dataset:
Mucus Aggregates in the Adriatic Sea: An Overview of Stages and Occurrences
Authors: Stachowitsch Michael , Fanuko Neda , Richter Marjan
Published: May 2008

Abstract. The wide range of macroscopic mucus aggregates in the Adriatic Sea is documented. These structures arc considered to be initially produced by diatoms. A differentiation into five states or stages: macroflocs, stringers, clouds, creamy surface layers, and gelatinous surface layers is proposed. This classification is based not only on size and shape, but also takes relative position in the water, stability, behavior, and effect on benthos into consideration. An interrelationship between these aggregates ‐ as different manifestations or phases of the same phenomenon ‐ is postulated.

Macroflocs and stringers arc more common. Larger aggregates (clouds, creamy layers, gelatinous layers) arc less frequent. The general term “marine snow” is inadequate to describe the entire range of aggregate sizes and shapes, while the Italian designation “mare sporco” (dirty sea) is misleading. Two massive occurrences of dense clouds coupled with surface accumulations were recorded in the Adriatic in 1988 and 1989. The effect of the various stages on the shallow coastal ecosystem of the Northern Adriatic Sea is discussed.
Tantulocarida (Crustacea: Maxillopoda): A New Taxon from the Temporary Meiobenthos1
Authors: Huys Rony
Published: May 2008

Abstract. Two new genera of Tantulocarida are described from the Ligurian deep sea (Western Mediterranean) off Corsica. Xenalytus scotophilia is referred to the Microdajidae and differs from Microdajus GREVE in thoracopodal segmentation as well as in the presence of coupling spines on thoracopod 6 and longitudinal lamellae on the cephalic shield. Aphotocentor styx is placed in the Deoterthridae and holds an intermediate position between Deoterthron BRADFORD & HEWITT and Boreotantulus HI/YS & BOXSHALL. Some aspects of cephalon internal structure are described for the first time and give a possible explanation for the mechanism of stylet protrusion. The external structures of the oral disc are described using SEM. The discovery of well‐developed muscles in the trunk and thoracopods is discussed in the light of the benthic phase the tantulus passes through. The boundary between the thorax and abdomen in the tantulus is reinterpreted, corroborating the 5–7‐5 bodyplan of the hypothetical urmaxillopodan as found in the Upper Cambrian Skaracarida and possibly also Dala peilertae MOLLER. Some aspects related to dispersal, infection, and feeding are reinterpreted or approached from a different perspective. SEM of Microdajus langi GREVE gives evidence that the tantuli hatch via a conspicuous slit located at the posterior end of the female trunk sac. A worldwide key to the tantulocaridan families and genera is given, and distributional records are compiled. It is suggested that Tantulocarida might be common representatives of the temporary meiobenthos and that their present species number represents only the tip of the iceberg.
The Reproduction of the Anemone Sagartia troglodytes (PRICE): No Influence of Tidal Manipulation
Authors: Hummel Herman , Bogaards Roelof H.
Published: May 2008

Abstract. .The reproductive cycle and the glycogen content were monitored in the subtidal anemone Sagartia troglodytes (PRICE). Moreover, these parameters were followed for periods of 3 to 30 days over the course of 1 year in anemones previously submerged in stagnant water and thus subjected to a reduced food supply. The anemones showed an annual reproductive cycle with, in contrast to previous studies. 2 spawning cycles. The glycogen content varied between 5 and 8% of the dry weight. Submersion in stagnant water did not alter the reproductive cycle or the glycogen content.

In the Oosterschelde the subtidal anemone Sagartia troglodytes showed an annual reproductive cycle with, in contrast to previous studies, 2 spawning cycles; spawning occurred in the periods February to May and July to September. The glycogen content varied between 5 and 8% of the dry weight. Prolonged submersion in stagnant water altered neither the reproductive cycle nor the glycogen content.
Microbial Biomass Dynamics Along a Trophic Gradient at the Atlantic Barrier Reef off Belize (Central America)
Authors: Herndl Gerhard J.
Published: May 2008

Abstract. Recent findings indicate that heterotrophic bacteria and not phytoplankton are the most numerous biomass components even in the euphotic zone of oligotrophic, open oceans. In this study it was hypothesized that the microbial biomass components change within a few hundred meters as oligotrophic water flows across the reef and becomes enriched with nutrients. Along a trophic gradient, four stations at the Atlantic Barrier Reef off Belize (Central America) were sampled for microbial biomass components. Phytoplankton biomass (measured as chlorophyll a) ranged from the most oligotrophic station (St. 1) to the most eutrophic station (St. 4) from 6.9–415.5 μg CI“‘ (assuming a C:chl a ratio of 30): heterotrophic bacterial biomass increased 4‐fold (from 10.1–46.4μg C 1‐1), heterotrophic nanoflagellate (HNAN) biomass increased from 4.6‐19ug C 1‐1, and cyanobacteria from 0.9‐4.5 μg C‐1‐1. Production estimates derived from seawater cultures revealed a 5‐fold increase in bacterial production from the oligotrophic station (3.7 ug C 1‐1 d‐1) to the eutrophic St. 4 (17.8ug C‐1‐d1‐1)‐ Cyanobacterial production rose from 1.1–3.5ug C‐1–d‐1 and HNAN production from 0.65‐1.13 μg C‐1‐1 ‐d‐1. While cyanobacteria contributed between 13 and 20% to the autotrophic plankton component in the oligotrophic waters, their contribution dropped to about 1 % at the eutrophic stations.
Phosphate Utilization in Phaeocystis pouchetii (Haptophyceae)
Authors: Veldhuis M.J. W. , Colijn F. , Admiraal W.
Published: May 2008

Abstract. .The phosphate uptake kinetics of single cells and colonies of the haptophycean alga Phaeocystis pouchetii were investigated in short‐ and long‐term experiments. In phosphate‐deprived cultures, the highest nutrient uptake rate (Vmax) of both growth forms appeared to be similar. However, the half‐saturation constant for phosphate uptake of the cells embedded in a colony (Ks= 3.08 μM) was considerably higher than that of the single cells (Ks= 0.31 μM). This is consistent with the existence of a diffusion barrier formed by the colony membrane and colonial mucus. Over a 24 h light/dark cycle, the phosphate assimilation rate in moderately limited colonies and single cells was nearly identical during the light period. In the following dark phase, colony cells maintained this uptake rate, whereas the uptake of the single cells diminished by 70 %. The high dark uptake rate in colonies ran parallel with the absorption and degradation of intracolonial carbon compounds, suggesting that the dissimilation of these compounds covers the energy requirements for phosphate uptake in the dark. In Phaeocystis cultures during a transition to phosphate depletion, a significant amount of phosphate was found in the colonial mucus, isolated by selective filtration. The possible absorption of phosphate by the mucus and the role of mucus in the energy budget seem to be an essential feature of phosphate uptake of colonies. Short‐term measurement of phosphate uptake in colony cells may therefore underestimate the phosphate uptake of the whole colony.
Deposit Feeding and Sediment:
Authors: Amon Rainer M. W. , Herndl Gerhard J.
Published: May 2008

Abstract. The feeding of the epibenthic deposit‐feeder Holothuria tubulosa GMELIN and its influence on sediment metabolism was investigated from February 1988 to February 1989. Water samples, specimens of H. tubulosa, and samples of freshly egested feces were taken by SCUBA diving in a 5 m deep seagrass bed at the Island of Ischia in the Gulf of Naples (Italy). Particulate organic carbon (POC), particulate organic nitrogen (PON), total particulate carbohydrates (PCHO), and bacterial biomass exhibited higher values in the foregut than in the surrounding sediment. Even the freshly egested feces were richer in the organic components than the sediment. The percentage of growing bacterial cells increased from 4.1 % in the sediment to 12.2 % in the foregut and declined to 11.6 % in the hindgut and 6.2 % in freshly egested feces.

On an annual average, absorption efficiency was highest for bacteria (x = 71%); for PON we calculated a mean absorption efficiency of 20.9%, for PCHO 19.5%. It was estimated that bacterial biomass supplied between 4 and 25 % of the respiratory carbon demand of H. tubulosa. We present evidence that the feeding activity of H. tubulosa stabilizes the bacterial community in the sediment. Furthermore, our data indicate that H. tubulosa reacts quickly to changing conditions, such as sedimented phytoplankton blooms.
Intraspecific Interactions and Risk of Predation for Dyspanopeus sayi (Decapoda: Xanthidae) Living on Polychaete (Filograna implexa, Serpulidae) Colonies*
Authors: Heck Kenneth L. , Hambrook Julie Anne
Published: May 2008

Abstract. Along the Atlantic coast of the United States, the mud crab Dyspanopeus sayi frequently occurs in crevices and depressions within aggregated calcareous tubes (termed “heads”) of the serpulid polychaete Filograna implexa. In New Jersey, U.S.A., waters, crab number was significantly correlated with the logarithm of worm tube colony volume. Laboratory experiments suggested that crabs compete for shelter within worm colonies. Additional laboratory experiments indicated that colony occupancy greatly decreased the risk of predation by blue crabs (Callinectes sapidus), and field tethering experiments also demonstrated that colony occupancy significantly decreased predation risk. Thus, the consequence of holding space on worm tube heads is a greatly increased probability of survival.
Fungal Invasion of Massive Corals
Authors: Raghukumar Chandralata , Raghukumar S.
Published: May 2008

Abstract. Five species of corals from the Andaman Islands in the Bay of Bengal (Indian Ocean) have been regularly found to have single or multiple necrotic patches. The occurrence of such corals with necrotic patches varied from 10–50% in the field. Sections revealed a septate dark brown mycelial fungus on the surface and subsurface of the dead patches in five coral species. The fungus was isolated in culture and identified as Scolecobasidium sp.

The fungus formed a distinct dense brown to black zone of 0.5‐1.5 cm width immediately below the surface of the corals. In terms of biomass, the fungus was estimated to contribute 3–5 mg cm ‐3 of coral skeleton.
Tackling the Sulfide Gradient: A Novel Strategy Involving Marine Nematodes and Chemoautotrophic Ectosymbionts
Authors: Ott J. A. , Novak R. , Schiemer F. , .Hentschel U , Nebelsick M. , Polz M.
Published: May 2008

Abstract.TheStilbonemutinue(marine free‐living nematodes) arc remarkable for cctosymbiotic bacteria, which cover the greatest part of their body in a highly ordered and species specific pattern. Using SEM we describe the main types of symbiotic cover and give evidence for the role of the bacteria in the nutrition of their host on the basis of stable carbon isotope ratios. In experimental systems the worms migrated repeatedly across a sulfide gradient during 12 h when sulfide concentrations were low, but stayed above the sulfide maximum at high concentrations. The migration across the chemocline exposes the symbionts alternately to reduced sulfur compounds and oxygen; this constitutes an alternative strategy to the ventilation/circulation systems in symbiotic macrofauna from sulfidic habitats.
Detritus Rolling Down a Vertical Cliff of the Ligurian Sea (Italy): The Écological Role in Hard Bottom Communities
Authors: Bavestrello Giorgio , Cattaneo‐Vietti Riccardo , Danovaro Roberto , Fabiano Mauro
Published: May 2008

Abstract. The detritus rolling down a vertical cliff was studied at Portofino Promontory (Ligurian Sea, Italy) at 16 m depth (January 1988‐ January 1989). The large amount of collected sediment is mainly due to the position of the traps; they collected not only the sedimenting material, but also the detritus rolling down along the cliff. The amount of sediment matter is 7 times greater in winter than in summer, showing a good correlation with rough seas and rain that cause a “mechanical cleaning” of animal and plant debris (Sérpulid tubes, shells, exuvias. leaves) along the cliff.

The Total Suspended Matter (TSM) in the water column shows maximum values in March and September. The organic fraction has an average concentration of 0.81 mg 1‐l. The phytoplanktonic biomass, measured as Chi a, shows an annual cycle with a peak in spring (1–2.7μg·l‐1). while in other periods of the year the value is about 0.3‐0.5 μg·1‐1. A significant relationship was found between organic detritus in the collected sédiments and the Chi a in the water column. The great influence of the rocky wall detritus on the normal trend of the TSM in the coastal water column is pointed out.
Effects of Meteorological Factors on Toxic Red Tide Events in Sabah, Malaysia
Authors: Usup Gires , Lung Yu Kim
Published: May 2008

Abstract. Red tides of the toxic dinoflagellate Pyrodinium bahamense var. compressum have occurred almost annually since 1976 in the coastal waters of the west coast of Sabah, Malaysia. Field obSérvations have indicated that the timings of these outbreaks could be linked to meteorological forcings. All the red tides have occurred during either the northeast or southwest monsoon periods. Matching of red tide outbreaks with total monthly rainfall, monthly‐averaged index of wind‐induced surface water mixing, and monthly‐averaged upwelling index for the period from 1975 to 1989 failed to show any definite pattern. However, more red tide events occurred in months with high mixing index values. The absence of definable patterns could be due to the use of monthly, rather than daily, values in the calculations.
Polychaete Communities Related to Plant Covering in the Médiolittoral and Infralittoral Zones of the Balearic Islands (Western Méditerranean)
Authors: Sarda Rafael
Published: May 2008

Abstract. The polychaete fauna of the subtidal in the médiolittoral and the infralittoral hard bottom zones of the Balearic Islands at depths from 0 to 40m contained 220 species. Five different polychaete communities could be identified by changes in abundance, species richness, species composition, diversity, and trophic structure. In the very clear waters of these islands the infralittoral zone extends to a depth of 40 m and allows us to investigate whether former proposed models of polychaete distribution can be extended to this particular situation.
Trawling or Visual Censuses? Methodological Bias in the Assessment of Fish Populations in Seagrass Beds
Authors: Harmelin‐Vivien Mireille L. , Francour Patrice
Published: May 2008

Abstract. Fishes associated with the seagrass Posidonia oceanica were censused both by skid trawl and visual counts around Ischia Island, Italy. Both sampling procedures were performed during the day in summer and in winter at two sites. Significant differences in the number of species, number of individuals, biomass, and trophic structure of the fish assemblage were observed between sampling methods. Fewer fish species were recorded by visual counts than by trawling. More individuals and a greater biomass, however, were recorded from visual counts. The population of macrocarnivores (Scorpaenidae, Serranidae) were better estimated by trawling, as were canopy‐dwellers (Syngnathidae; Symphodus rostratus) and benthic species (Gobiidae; Blenniidae; Bothidae). Conversely, good swimmers (Sparidae; Coris julis, Symphodus spp.), and planktivorous fishes (Centracanthidae, Pomacentridae) mostly escaped the trawl and were better assessed by visual counts. The importance of methodological biases differed from one season to the other and was higher in summer than in winter. Particular attention should be paid to the biases induced by sampling techniques when interpreting data, and different sampling methods should be used to accurately study the fish assemblages of seagrass meadows.
Ecology of Vibrios in the Oliveri‐Tindari Lagoon (Messina), Two‐Year Study
Authors: Zaccone Renata , Crisafi Ermanno , Genovese Lucrezia
Published: May 2008

Abstract. A two‐year ecological study in the Oliveri‐Tindari (Messina) brackish water ponds evaluated the quantitative and qualitative distribution of Vibrio species in relation to the physicochemical conditions of the ponds.

The evaluation of 204 samples shows a general relationship between the halophilic vibrios and water temperature. In particular this relationship is stronger for the Vibrio fraction able to grow at 37°C, i. e., those species related to human infections. On the other hand, the halophilic vibrios show no relation with the index of fecal contamination.

The ecology of V. parahaemolyticus is discussed in relation to the salinity of Marinello pond.

The distribution of V. cholerae non O1, isolated from all ponds, shows that this microorganism can be considered as autochthonous in coastal environments.
Vegetative Reproduction in Posidonia oceanica
Authors: Molenaar Heike , Meinesz Alexandre
Published: May 2008

Abstract. In an investigation of vegetative reproduction in Posidonia oceanica, carried out in Corsica, survival and development were studied in initially orthotropic rhizomes transplanted to different depths. Batches of transplants originating from 30m depth and replanted in shallower water (3, 14, and 20m) showed survival of 96 to 100% after eleven months, with ramification in 42% of the transplants and root formation in 44%. After the same time interval, batches originating from 3m depth and transplanted to deeper water showed lower survival ‐59% at 14m, 41% at 29m, and 3% at 36m ‐ complete absence of ramification, and rooting in only one batch. Transplantation to water shallower than their origin was favorable for survival, growth, and development, while transplantation to deeper water led to progressively lower survival, growth, and development of the shoots. Whatever the depth at which they were replanted horizontally, most transplants changed their growth mode from orthotropic to plagiotropic, as evidenced by both the change in leaf growth angle from horizontal to oblique and by the development of shorter, narrower leaves.
Quantitative Benthic Community Structure in Blanca Bay and Its Relationship With Organic Enrichment*
Authors: Elias Rodolfo
Published: May 2008

Abstract. A two year benthic sampling program of a 2000 km2 area, covering 22 stations, showed a dominance of deposit‐feeding polychaetes. The quantitative structure of the three infaunal assemblages was related to a salinity gradient: the inner and outer regions were inhabited by, respectively, mixohaline and euhaline associations, both quantitatively related to granulometric facies of sediment. Species diversity was very low in the inner region, although abundance of opportunistic species was high. In the outer region, abundance and diversity were more stable, with an increasing number of species.

A comparison of species number and abundance with Species‐Abundance‐Biomass curves from enriched environments showed that the inner region of Bianca Bay may be considered as an organically enriched environment. Scoloplos, a species associated with organic enrichment, and dense terebellid belts were present in great abundances in front of sewage outflows. The spatial distribution of heterotrophic bacteria and the bivalves Corbula and Nucula also followed this pattern.
Population Dynamics and Life History Characteristics of the Blue Crabs Callinectes similis and C. sapidus in Bay Environments of the Northern Gulf of Mexico
Authors: Hsueh Pan‐Wen , McClintock James B. , Hopkins Thomas S.
Published: May 2008

Abstract. The population dynamics and life history characteristics of Callinectes similis and C. sapidus in the Mobile Bay‐Mississippi Sound estuarine system of the northern Gulf of Mexico were studied. We report that C. similis is numerically dominant in open‐bays, while C. sapidus is more abundant in shallow salt marshes. Juvenile C. similis recruit into both open‐bays and salt marshes, but juvenile C. sapidus primarily recruit into shallow salt marshes. Sex ratios of C. similis and C. sapidus were generally skewed towards higher proportions of males than females. Callinectes similis appears to have a life cycle similar to that of C. sapidus. Egg‐carrying C. similis migrate to higher salinity waters and presumably release larvae to nearshore shelf waters; following development, the larvae re‐invade estuaries as megalopae. Juvenile C. similis grow more slowly than C. sapidus. This may be attributable to reduced feeding rates. Marked differences in fecundity and reproductive effort were found between these species. Callinectes similis and C. sapidus, respectively, produced 2.4–5.5 times 105 and 2.1–3.2 times 106 eggs and invested 24–49 and 171–372 kJ per brood. Rhizocephalan barnacle infestation by Loxothylacus texanus was encountered in C. sapidus, while sympatric C. similis were free of this rhizocephalan parasite.
La Réponse aux Couleurs chez Dicentrarchus labrax (Moronidae), Placé en Situation de «Self‐feeding», et de Choix Multiple: Response to Colours in Dicentrarchus labrax (Moronidae), in a Self‐Feeding and Multiple Choice Condition
Authors: Kentouri M. , Anthouard M. , Divanach P.
Published: May 2008

Abstract. A population of sea‐bass, housed under semi‐natural and self‐feeding conditions, was presented with six different coloured levers. Their choices tended to favour more colour‐contrasted levers and were greatly affected by environmental conditions such as stress factors, circadian period, season, and thermal fluctuations. A correlation was observed between increases in instrumental acitivity, indicating an increase in energetic requirements, and a widening of choices in the exploitation of the coloured levers.

Consequences of these behaviours were considered in relation to predator pressure that the fish imposes on potential prey populations in the natural environment, and in relation to the initiation of feeding activity when the fish are maintained in captivity and under self‐feeding conditions.
Phenolics and Proteins Affecting Palatability of Spartina Leaves to the Gastropod Littoraria irrorata
Authors: Bärlocher Felix , Newell Steven Y.
Published: May 2008

Along the southeastern coast of the United States, the saltmarsh periwinkle Littoraria irrorata is a major consumer of Spartina alterniflora. It prefers to feed on dead rather than living plants. During senescence and early decay, S. alterniflora leaves become colonized by fungi, their phenolic content declines, and their lipid content increases. In this study, the food preferences of L. irrorata were assessed by offering intact leaves or leaf powder suspended in agar. Relative palatabilities were determined by measuring the weight loss of intact leaves, or by estimating the area of feeding marks left on the surface of leaf powder suspensions. Both techniques demonstrated a clear preference for standing dead rather than yellow‐green (senescent) leaves. Yellow‐green leaves contained methanol‐soluble feeding deterrents. A comparable deterrent effect could be achieved by adding ferulic acid, a phenolic compound common in yellow‐green S. alterniflora, to leaf powder. The deterrent effects of methanol extracts or ferulic acid could be neutralized by simultaneously adding fungal mycelium or BSA. Littoraria irrorata preferred leaves colonized by fungi or bacteria over sterile leaves. When offered a choice of sterile leaves colonized by different fungi, the results were variable. In one experiment, L. irrorata clearly preferred one of three leaffungus combinations. The same preference was shown after the food items were treated with methanol/chloroform to remove lipids. In a second experiment with four other fungal strains, there was only a clear preference for one leaf‐fungus combination after removal of lipids. The results suggest that the saltmarsh periwinkle prefers S. alterniflora leaves with low concentrations of phenolic deterrents, most likely ferulic acid, and with sufficient fungal biomass. The food choice may be influenced to a smaller degree by fungal components, which, depending on the species or strain, may be lipids or other compounds.
Variations in the Number of Intestinal Loops in Scaphopoda (Mollusca)
Authors: Steiner Gerhard
Published: May 2008

Abstract. The intestinal loops of two species of the genus Bathoxiphus (Entalinidae) and of Cadulus aberrans (Gadilidae) have been reconstructed from serial sections. The results are compared to the ‘textbook scaphopod’Antalis dentalis having the hindgut coiled in three loops. Bathoxiphus ensiculus has four or five intestinal loops, B. sp. S 153 four, and C. aberrans two. The buccal pouch contents included Foraminifera in all species, with agglomerates of sediment being found only in Bathoxiphus and Antalis. The mean ratio of intestinal length to body length ranges from 1.05 in B. ensiculus, over 0.98 in the four‐looped B. sp. S 153, to 0.7 in A. dentalis and 0.6 in the twice‐looped C. aberrans. The correlation of intestinal length with diet—additional deposit‐feeding in Bathoxiphus and highly specialized ‘carnivory’ in C. aberrans—is probable. Despite the differences in feeding ecology, the elongated hindgut of both deep‐sea species of Bathoxiphus resembles the adaptations of some bivalves to poorly nutritious deep‐sea sediments.
Significance of the Virus‐Rich 2–200 nm Size Fraction of Seawater for Heterotrophic Flagellates: I. Impact on Growth
Authors: Pesan Barbara F. , Weinbauer Markus G. , Peduzzi Peter
Published: May 2008

Abstract. The effect of artificially changing the concentration of naturally occurring free virus‐like particles (VLPs) on growth of marine heterotrophic flagellates was tested in batch cultures using ultrafiltration technology. This manipulation influenced the course of flagellate growth markedly. During 1 week of incubation the growth of 4 tested flagellate strains (Oxyrrhis marina, Paraphysomonas imperforata, Petalomonas cantuscygni, Pteridomonas danica) was strongly favoured after increasing the VLP concentration. Bacteria, however, were repressed in these treatments beyond 50 h. In cultures with natural seawater microbiota, we both reduced and enriched the concentration of VLPs. In these cultures, reduction of material in the virus‐rich 2–200 nm size fraction led to a strong positive growth response of heterotrophic flagellates. In VLP‐enriched treatments of natural seawater microbiota a tendency toward growth stimulation was also found, although this was not significant. Enrichment with VLPs caused no recognizable mortality either in cultured flagellate strains or in naturally occurring flagellate communities. However, it is suggested that a highly bioactive component must be present in the virus‐rich 2–200 nm size fraction. Virus‐like particles are discussed as possible candidates influencing heterotrophic flagellate community successions.
Description of the Phytoplanktonic Community of the Oligotrophic Waters of the SE Aegean Sea (Mediterranean)
Authors: Ignatiades L. , Georgopoulos D. , Karydis M.
Published: May 2008

Abstract. A seasonal sampling program of five stations off the Island of Rhodes (SE Aegean Sea) was carried out in 1983–1984. Temperature, salinity, Secchi disk transparency, P‐PO4, N‐NO3, N‐NO2, N‐NH3, Si‐SiO2, and chl a were measured and phytoplankton species recorded. Cell concentrations and chl a varied seasonally. with the highest values in summer (l.2 times 104 ‐1‐‐1 total mean cells; 0.13 mgam‐3 total mean chl a) and the lowest in winter (2.3 times 103, 1‐‐1 total mean cells; 0.06 mg.m‐‐ total mean chl a). A variation in cell abundance among stations was also noted. Quantitative relationships among the recorded taxa showed that diatoms and dinoflagellates were richer in species composition (88 and 58 total species, respectively) than coccolithophores (8 species) and other flagellates (8 species). Comparison of phytoplankton samples from different depths and stations by cluster analysis showed an irregularity or discontinuity in species associations. The SE Aegean Sea was characterized as oligotrophic on the basis of the estimated nutrient and phytoplankton concentration levels.
Community Structure of Soft‐Bottom Macrobenthos of the Newport Submarine Canyon, California
Authors: Maurer D. , Robertson G. , Gerlinger T.
Published: May 2008

Abstract. The hypothesis that benthic community structure of soft‐bottom macrobenthos does not change throughout the Newport Submarine Canyon, California was tested with a set of quantitative Van Veen (0.1 m2) samples down the canyon axis. There was a marked break in community structure between Station C4 (187 m) and Station C5 (324 m). Comparison of the present study with work conducted earlier indicates that mean number of species, abundance, and biomass were not significantly different between 1962 and 1978. Within the canyon, species diversity was high compared to 12 other southern California canyons. This difference was mainly due to sampling effort and the inactive nature of the Newport Canyon.

Over 500 species are identified from Newport Canyon, California from 1978 to 1990. The diversity of soft‐bottom macrobenthos in shallow to intermediate depths of Newport Canyon is much higher than in other southern California canyons (Hartman, 1963). This difference is mainly due to sampling effort and the inactive nature of Newport Canyon which facilitates the maturation of soft‐bottom communities; in contrast to active canyons which through turbidity currents frequently disrupt the water‐sediment interface. Conditions within Newport Canyon have been stable for benthic community structure for at least 16 years and probably closer to 25 years. The hypothesis examined here shows that community structure is not homogeneous with depth along its axis, but has a marked break between 187 m and 324 m. Finally, we are now in a position to examine hypotheses concerning the effects of an ocean outfall on benthic community structure between the shelf and the canyon.
Stochastic Events and Dynamics of a Mangrove Root Epifaunal Community
Authors: Bingham B. L. , Young C. M.
Published: May 2008

Abstract. Submerged roots of red mangroves (Rhizophora mangle) in the Florida Keys were photographed at 1– or 2‐month intervals for 38 months to measure population dynamics of the epifaunal invertebrate species. Photographs were analysed for species composition and abundance and information on life spans, persistence, mortality, and seasonality. Larval recruitment to artificial surfaces was used to assess reproductive seasonality. As a measure of stability, populations were tested for narrow stochastic boundedness.

In contrast to reports for a tropical mangrove root community, the Florida Keys root community showed enormous variability despite being dominated by long‐lived species with low, largely non‐seasonal recruitment. Species composition on individual roots changed dramatically on short time scales. Populations of the major species were not narrowly bounded on most roots and there was little evidence for a closely regulated community.

Variability of this community related to the frequency and intensity of stochastic perturbations. Physical disturbance due to strong tidal Rows appeared to be the most important structuring process. Species‐specific predation and fragmentation of sponges were also important. These features contribute to the instability of the community by producing dramatic fluctuations in species abundances and preventing competitive processes from producing a more stable, equilibrium community. Temporal measurement scale was an additional important consideration in this habitat. Structuring processes occurred on very short time scales (1–2 months) and analysis on longer time scales gave inaccurate impressions of community dynamics.
Low‐Tide Exposure of Sponges in a Caribbean Mangrove Community
Authors: Rützler K.
Published: May 2008

Abstract.Sponges on subtidal red‐mangrove prop roots may become exposed to air many times per year during very low tides. Full exposure is stressful and potentially fatal, particularly if occurring in full sun. Large root sponges show distinct species zonation between mean low water and ‐0.5 m.Haliclona implexiformisandLissodendoryx isodictyalis arenear the top whileScopalina ruetzleriare near the lower end of the range. Temporary experimental desiccation resulted in 100% recovery of all three species after they had been exposed to either sun or shade for up to 2 h.Scopalinais the least resistant and lost over 90% tissue within 3 days after the 4‐h and 6‐h experiments; the remaining cell mass succumbed to infestation by microbes.HaliclonaandLissodendoryxrecovered from as much as 6 h in full sun but lost 85% and 80% of the original tissue volume, respectively. InLissodendoryx, clusters of larvae developed in the regenerating fragments. Water loss tolerated by the three species is estimated as 66% of wet weight inHaliclona, 54% inLissodendoryxand 38% inScopalina. Salinity of interstitial seawater (pore water) extracted from exposed sponges rose from ambient 3.5% to 4.348% after 1 h, to 5.1–5.9% after 6 h. Most endobionts died or left their host during this last phase. Natural vertical zonation in these sponges reflects their resistance to tidal exposure.
Modern and Palaeoecological Significance of the Radiolarian Spongaster tetras tetras Ehrenberg in the Eastern Equatorial Pacifics
Authors: Haslett S. K.
Published: May 2008

Abstract. Spongaster tetras tetras Ehrenberg has long been considered by palaeontologists as a species indicative of warm (>21 C) sea‐surface temperatures (SSTs) and tropical/subtropical conditions. However. a comparison of the Plio‐Pleistocene record of S. t. tetras in the eastern equatorial Pacific (Ocean Drilling Program Hole 677A) with CaCO3, δ18O, and δ13C records reveals that S. t. tetras is most commonly present during periods of intense upwelling, often coinciding with isotopically identified glacial stages. when surface productivity and salinity are high, and SST is expected to be relatively low. Maximum S. t. tetras abundance (1.8% of radiolaria counted) occurred during a cool interglacial. when productivity and salinity were high, wind‐driven upwelling intense, and SST relatively warmer than during glacial maxima. It appears that in the eastern equatorial Pacific upwelling system, SSTs are generally too cold (<21 C) for S. t. tetras to survive; however, S. t. tetras can tolerate (with populations <0.7%) cold SSTs if productivity and salinity are increased (due to upwelling), and flourishes (>0.7–> 1.8%) if this is coupled with relatively warm SSTs. This micropalaeontological study Corroborates the findings of an earlier research program on living S. t. tetras cultures (Anderson et al., 1989a.b, c).
A Wandering Population of the HexactinelIid Sponge Pheronema carpenteri on the Continental Slope off Morocco, Northwest Africa
Authors: Barthel D. , Tendal O. S. , Thiel H.
Published: May 2008

Abstract. A photo transect along the continental slope off Morocco, Northwest Africa revealed an extensive population of the hexactinellid sponge Pheronema carpenteri (thomson, 1869). The population forms a distinct band parallel to the depth contours between 740 and 820 m. Because of the long persistence of dead hexactinellid skeletons, living and dead individuals of P. carpenteri were recorded, together with the spicular remains of disintegrated individuals. Furthermore, the presence of small individuals and that of other epifaunal elements were recorded. The peaks of abundance of dead and living sponges, respectively. are not at the same depth, the maximum abundance of living individuals being above that of the dead ones; small, i.e., probably young P. carpenteri individuals were observed only in the upper zone. This can be interpreted as a successional phenomenon, i.e., the population of P. carpenteri has apparently ‘moved’ slowly up the slope. The fauna associated with the P. carpenteri population along the Moroccan coast seems to be much poorer than that associated with another band‐shaped population in the Porcupine Seabight investigated by Bett & Rice (1992). indicating that the presence of dense hexactinellid populations does not invariably lead to conspicuous benthic faunal enrichment.
Contribution of Sponge Spicules to the Composition of Biogenic Silica in the Ligurian Sea
Authors: Bavestrello Giorgio , Cattaneo‐Vietti Riccardo , Cerrano Carlo , Cerutti Stefania , Sará Michele
Published: May 2008

Abstract. The importance of sponge spicules in the turnover of biogenic silica (BSi) in the detritic bottoms of the Eastern Ligurian Riviera was evaluated by studying sediment cores and the detrital matter collected by a trap over a one year period.

This study made evident that: i) Sponge spicules represent the main component of the BSi both in the sediments and in the trapped matter; ii) A correlation exists between the sponge biomass present on the overhanging cliff and the amount of sponge spicules found in the sediment below; iii) Inside the sediments, a superficial layer (10 cm deep) characterized by intensive silica dissolution processes can be observed; and iv) The amount of spicules collected using the trap is not constant throughout the year, but shows a characteristic trend with low values in spring and summer and high values in autumn and winter.
Habitat Provision for Meiofauna by Fucus serratus Epifauna with Particular Data on the Flatworm Monocelis lineata
Authors: Boaden Pat J. S.
Published: May 2008

Abstract. Fucus serratus provides a habitable site For much epifauna if conditions are right. Epifaunal colonies in their turn as well Provide habitats in which meiofauna can dwell. Thus micro‐environment is provided which is Dependent on colony‐species, ‐size and silt for its riches. Analysis of population data shows the facts are Turbellarian abundance rarely relates to other taxa, However the flatworms' population count Closely relates to total meiofaunal amount. Experiments on bryozoan‐choice by Monocelis lineata show This worm prefers Flustrellidra as a place to go. This may in part be due to thigmotactic deference But mainly seems related to a feeding preference. In addition to behaviour towards food and concavity, Responses are shown to light, temperature, current and gravity. In the discussion thus it is partly explained How meiofauna finds epifauna and there is maintained.
Biogenic and Geochemical Properties of Intertidal Biosedimentary Deposits Related to Mytilus Beds
Authors: HERTWECK GÜTHER , LIEBEZEIT GERD
Published: May 2008

Abstract. Biofacies development, sedimentology, and geochemical properties of intertidal Mytilus beds in the German Wadden Sea have been studied in vertical profiles in situ and in box core samples. Characteristic features of both the live mussel beds and the underlying sediment sequences were detected. The deposition of faeces, pseudofaeces, and trapped fine‐grained material results in the formation of well‐defined biosedimentary mud layers of several centimetres thickness. The initial stages of this deposition process were observed in a young, growing Myrilus colony over a 17‐month period. In an old mussel bed, being in state of decline, both reworking of dead shells and erosion of the biosedimentary mud layers were recognisable. However, deeper parts of the sediment column reveal shell horizons rich in “pairs” of dead Mytilus shells, i.e., corresponding right and left valves found close together. These represent subrecent records of former Mytilus colonisation. Historically, they point to long‐term occurrence of mussel beds at typical localities, in the framework of fluctuation and patchiness patterns, in the more recent past. On the other hand, mud banks at tidal flat margins adjacent to channels suggest a high preservation potential of biosedimentary mud layers in the low‐water level environment. Geochemical properties of these muddy sediments corroborate their biodepositional origin.
Biocorrosion by Bivalves
Authors: Kleemann Karl
Published: May 2008

Abstract.A survey of the historical background of chemically boring bivalves and the proposed methods of boring, indications for biocorrosion, observations, and experimental results are provided. The regional impact to the ecosystem is discussed with examples from the N. Adriatic, Caribbean, and E. Pacific. The fossil record of the geologically oldest biocorroders extends back into the Mesozoic,i.e., U. Triassic forLithophagaand Jurassic for gastrochaenids.
Plankton as a Factor Modifying the Physical Characteristics in the Marine Environment
Authors: Tokarev Yuriy N.
Published: May 2008

Abstract. Some hydrophysical environmental parameters (e.g. temperature, salinity, transparency, flows, erc.) are known to profoundly affect the structural and functional characteristics and species composition of plankton communities. The purpose of the present work was to assess the opposite ‐ the influence of qualitative and quantitative characteristics of plankton on some optical (light transmission. optical density) and acoustic (sound volume backscattering strength) characteristics in the Black Sea. The influence of specific features (shape, size and color) of planktonic unicells on light attenuation in seawater was examined in laboratory experiments. The data from field studies on variability of statistic characteristics of sound volume backscattering strength in upper productive water layer, depending on species composition and numbers of zooplankton, are given.
Some Aspects of Fluorite and Vaterite Precipitation in Marine Environments*
Authors: Wittmann Karl J. , Ariani Antonio P.
Published: May 2008

Abstract. Mysid shrimps of the genus Schistornysis precipitate either fluorite (CaF2; S. spiritus) or vaterite (CaCO3; S. assimilis) for the formation of static bodies (statoliths). In S. assirnilis, 2.44 μg calcium and 3.66 μg carbonate are precipitated for each statolith. This corresponds to 69 mg or 30 mg ambient water, respectively, using the ion content of seawater for stoichiometrical comparison. Concentmtion factors of calcium or carbonate in relation to equivalent amounts of ambient water in the statocyst cavity are 760 or 3100, respectively. In S. spiritus, 3.79 μg calcium and 3.60 μg fluoride are precipitated. This corresponds to 9.3 mg or 2788 mg ambient water, respectively. Concentration factors with respect to statocyst water mass are 610 or 183.000. respectively. Ile high fluoride accumulation for the formation of statoliths alone contributes to a fluoride content of 4500 ppm with respect to body dry weight

A minimum estimate for the role of mysids in the global fluoride cycle suggests that at least 62,000 tons of fluoride are bound in mysid statoliths. Due to rapid turnover of about seven days, mysid fluorite statoliths are a crucial factor by contributing to a turnover of at most 570,000 years for overall fluoride in the oceanic system.
Annual Variation of Benthic Nutrient Fluxes in Shallow Coastal Waters (Gulf of Trieste, Northern Adriatic Sea)
Authors: Bertuzzi Alessandra , Faganeli Jadran , Bflmbati Antonio
Published: May 2008

Abstract. Benthic fluxes of dissolved N. Si and P nutrients, alkalinity, dissolved inorganic C (DIC), and O2 from sediments in the Gulf of Trieste (northern Adriatic, Italy) were measured monthly for 16 months, using laboratory incubated flux chambers at in siru temperatures in the dark.

The annual average fluxes were: 02 = ‐19.3 ± 8.2, DIC = 13.7 ± 9.6, NO3 = ‐0.04 ± 0.16, NH4 = 0.3 ± 0.4. PO4= 4.001 ± 0.01, Si = 0.9 ± 0.1 mmol m‐2 d‐1, with strong temporal fluctuations. The highest effluxes of all nutrients and DIC were observed in the summer. Small effluxes of DIC and NH4 and influxes of Si and PO4 were observed in late winter. Only NH4 (ca. 50%) and Si (ca. 70%) fluxes were significantly correlated with temperature. This correlation suggests that the rate of downward input and the quality of sedimented organic matter (autochthonous and allochthonous) were superimposed on the temperature fluctuations. High DIC, NH4 and Si effluxes observed in May 1993 during low temperature were due to the degradation of sedimentary organic matter produced by an early spring bloom of benthic microalgae which occurred about 6 weeks earlies while the autumn phytoplankton bloom was simultaneously reflected in enhanced benthic fluxes due to higher temperature.

The role of benthic biological advection in this transport across the sediment‐water interface, evaluated by comparison between measured benthic and calculated diffusive fluxes from nutrient pore water concentrations, was of minor importance. This is probably due to low infaunal activity throughout the year it was localized mostly in the narrow surficial layer. The annual average diffusive fluxes of NH4 and PO4 were higher than those measured, probably due to the presence of nitrificationdenitrifi‐cation processes and redox‐dependent chemical reactions at the oxic sediment‐water interface, respectively. Only during bottom‐water hypoxia in September 1993 did strong PO4 effluxes prevail. Calculations based on the Redfield stoichiometry of oxic decomposition of organic N to NH4 and NO3, and differences between diffusive and measured NH4 fluxes showed that denitrifkation averaged 0.8 mmol m‐2 d‐1. Significant correlations between NH4 and PO4 DIC and Si, and NH4 and Si fluxes suggested their parallel regeneration and utilization at the sediment‐water interface.

The nutrient fluxes observed were not significantly linked to O2 consumption, suggesting also that anaerobic oxidation processes were important at the sediment‐water interface in the gulf. The N, P and Si nutriqnts released from sediment pore waters are probably utilized in benthic microalgal and bottorn‐hater primary production. This indicates that pelagic and benthic communities in the central part of the Gulf of Trieste function relatively independently of each other.
The Effects of Reduced Oxygen Content on Predation and Siphon Cropping by the Brown Shrimp, Crangon crangon
Authors: Sandberg Eva , Tallqvist Minna , Bonsdorff Erik
Published: May 2008

Abstract. Aquarium experiments were performed to test for critical oxygen levels in relation to the predation efficiency of C. crangon. Short‐term (60 h) experiments where done in normoxia (> 95%). 50, 40.30, and 20% oxygen saturation with the amphipod Bathyporeiapilosa as prey. A significantly reduced predation rate was detected at 30% oxygen. Sublethal effects of C. crangon on adult Macoma balthica (mainly by siphon cropping) were studied by measuring the condition of the clams (morphometric, somatic, and biochemical). To test for these effects experiments were conducted under normoxia and moderate hypoxia (40% oxygen); Condition and siphon indices revealed no change in condition after a 3‐week exposure to moderate hypoxia, while a significant reduction in the condition of adult clams was found in both normoxia and hypoxia when subjected to siphon cropping by C. crangon. No enhanced siphon cropping could be detected due to hypoxia.

The results indicate that C. crangon is able to maintain its predatory role until a level of 30% oxygen in short‐term exposure. After a 20% oxygen level, however, the abiotic stress alters the functional role of C. crangon as a predator, indicating a threshold of 20–302 oxygen for the normal functioning of the predator‐prey food webs.