bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physiology of Laminaria
Authors: Conolly Nichola J. , Drew Edward A. 
Published: May 2008

Abstract.Sporophytes ofLaminaria digitataandL. saccharinawere collected from the shore at different times of year. Intact sporophytes of both species, and discs cut fromL. digitatalamina tissue were maintained for several weeks in laboratory cultures under various nitrate, phosphate, temperature and daylength regimes. Substrate‐saturated uptake rates of approximately 24 μgN g dry weight‐1h‐1from 20 μM nitrate and 8 μgP g dry weight‐1h‐1from 10 μM phosphate were more than sufficient to account for internal nitrogen and phosphorus accumulation. Other nitrogen sources ‐ nitrite, ammonium and urea ‐ were also taken up, independently of each other, and supported growth.During the late spring decline of ambient nutrient levels, when growth rates on the shore also decline markedly, enrichment with nitrate (15 μM) and phosphate (3μ) together prevented this decline and also maintained peak photosynthetic rates (net photosynthesis = 10.4 μlO2cm‐2h‐1) which otherwise dropped to 4.5 μO2cm‐2h‐1over 47 days at ambient nutrient levels (0.5 μM nitrate and phosphate). Slow summer growth rates in June/July were enhanced to greater than spring peak values by combined nitrate (7.5 μM) and phosphate (1.8 μM) enrichment; neither was sufficient alone, although the individual nutrients were accumulated internally. A lesser, but significant enhancement was also achieved in September.In midwinter, nutrient enhancement itself (10.5 μM nitrate and 3.0 μM phosphate) had a small effect on growth rates only if summer water temperature (15°C) was used, but the dramatic effect of an increased photoperiod (7.5 to 17.5 h) was in excess of that expected for the increased radiant energy available. This was found to be due, at least inL. digitaiadiscs, to the re‐establishment of a surface meristoderm in the dormant winter tissue; this was particularly active with high phosphate supply. Growth of the new lamina in January on the shore was much reduced if the old lamina was removed, although the time of initiation of new growth remained unchanged. In the laboratory, the old lamina was found to be a source of nitrogen for new lamina but not of fixed carbon or phosphorus. New lamina photosynthesis, manifest as mannitol accumulation, was directly proportional to phosphate supply up to at least 7.5 μM phosphate. Mannitol accumulation was then suppressed by a nitrate supply above 12 um, presumably by diversion of fixed carbon to other biosynthetic pathways.
Distribution and Ecology of Epiphytic Portfera in two Posidonia oceanica (L.) DELILE Meadows of the Ligurian and Tyrrhenian Sea*
Authors: Pansini M. , Pronzato R. 
Published: May 2008

Abstract. Two geographically distant Posidonia meadows located in the Western Mediterranean Sea were analysed using SCUBA diver‐taken samples. The material was collected at depths of 1, 5, 15 and 30 m, sampling all the plants within a 400cm2 area, as well as selecting bundles with epiphytic Porifera from a 5 m: area divided into quadrates. The effectiveness of both methods is compared, as the data in the literature were obtained from dredgings.The abundance and distribution of the seventy‐five identified species of Porifera were examined, taking into account the depth of the sampling stations and additional environmental factors. The two meadows studied were compared using statistical methods; some doubts are raised about the existence of a specific Porifera population characteristic of Posidonia beds.
The Feeding Apparatus in four Pacific Tube Blennies (Te/eos fei: Chaenopsidae):
Authors: Kotrschal Kurt , Lindquist David G. 
Published: May 2008

Abstract. Tube blennies (Chaenopsidae) have the largest relative mouth size compared with other blennioids. Their peculiar oral jaw apparatus may be interpreted as adaptation towards opportunistic feeding, making a wide spectrum of prey types and sizes accessible for these “hemisessile” fishes.Three sympatric species of Gulf of California Acanthemblemaria show different, though overlapping habitat and microhabitat utilization, but are nearly identical in feeding. Accordingly, sizes and shapes of the oral jaw apparati are very similar in the species under consideration. Possible reasons for this apparent lack of ecomorphological divergence are discussed.
Structural Adaptations to Light Reception in Two Morphotypes of Corallina elongata ELLIS & SOLAND
Authors: Algarra Patricia , Niell F. Xavier 
Published: May 2008

Abstract. A tentative method is developed to determine the assimilative surface and the total and active photosynthetic volume in caespitose algal communities. The estimation of these variables and the analysis of photosynthetic pigments allow the description of structural adaptive responses in relation to light reception in two morphotypes of Corallina elongata, i. e., those growing in sunny and shaded intertidal localities.A cross transplantation of both morphotypes demonstrates that one type rapidly converts to the other. This indicates an adaptivity of morphology and pigment composition.The results presented in this work as well as the comparison between intertidal and terrestrial communities suggest that both have a similar potential efficiency in harvesting the incident radiation, but that the degree of compactation of the photosynthetic apparatus (Leaf Area Index) is different.
The Ecology of Amorphous Aggregations (Marine Snow) in the Northern Adriatic Sea:
Authors: Herndl Gerhard J. , Peduzzi Peter 
Published: May 2008

Abstract. In the water‐column of the Gulf of Trieste (Northern Adriatic Sea) flocculent, amorphous aggregates known as marine snow reach maximum density and dimensions up to 20cm in diameter during summer months. Sampling of these fragile macro‐aggregates was carried out by SCUBA‐divers.A large detrital component was found to be embedded in an organic matrix together with a large array of intact phytoplankton species. Heterotrophic bacterial density ranged from 2–65 × 108 cells‐g‐1 (marine snow dry wt) and is therefore of the same order of magnitude as in the surface layer of the sediments of the Gulf. In terms of biomass, bacteria reached only 30–95% of heterotrophic microflagellates.A mean abundance of marine snow of 5g (marine snow dry wt) m‐3 was obtained for the water‐column above the pyenolinc. At this boundary layer, however, a mean abundance of about 10g (marine snow dry wt) m‐3 led to the formation of a distinct, 10‐50cm thick layer. Based on these data and sedimentation rates of marine snow to the pyenoclinc (38 g [marine snow dry wt] m‐2 d‐1) the potential ecological significance of these macro‐aggregates for the pelagic system of the Gulf of Trieste is discussed.
Diel Activity Patterns and Foraging Dynamics of the Sea Urchin Tripneustes ventricosus in a Tropical Seagrass Community and a Reef Environment (Virgin Islands)
Authors: Tertschnig Wolfram P. 
Published: May 2008

Abstract. Feeding and movement activity patterns and the foraging behavior of the sea urchin Tripneustes ventricosus were investigated in a Thalassia testudinum seagrass bed and on a patch reef at St. Croix, U.S. Virgin Islands.Most of T. ventricosus in the seagrass bed fed during both the day and night. Consumption of seagrass blades amounted to 1.4 g dw · individual‐1· d‐1 (mean sea urchin size 12.1 cm ambitus diameter). The population consumed approximately 3.6% of the daily seagrass production.The movement of T. ventricosus was diel with high nocturnal activity levels and rates of locomotion, and little activity during daylight hours. Foraging activity was reduced under turbulent conditions. Movement rates were not governed by food availability. T. ventricosus travelled 3.7 m · d‐1 on the patch reef. Individuals in the seagrass bed moved 8.8 m · d‐1, most of which was accomplished during the night. The area traversed contained more than one hundred times the amount of food consumed daily. It is assumed that this behavior requires high energy expenditures for locomotion, thus yielding a low net energy profit from feeding.The high rate of movement in seagrass beds may represent an innate behavioral adaptation to predation by night‐active helmet conchs (Cassis spp.). Fitness optimization by T. ventricosus may have been achieved by minimizing the predation risk during night hours. In an evolutionary context, survival by means of an increased energy expenditure for locomotion may compensate for the lower net energy gain from foraging.
Descriptive Analysis and Classification of Benthic Communities in Some Mediterranean Coastal Lagoons (Central Italy)
Authors: Gravina M. F. , Ardizzone G. D. , Scaletta F. , Chimenz C. 
Published: May 2008

Abstract. Benthic samples were taken seasonally at 32 stations in five coastal lagoons of Central Italy (Fogliano, Monaci, Caprolace, Fondi, and Lungo) during a two‐year period (1982–1984). Composition and distribution of benthic populations in each lagoon as well as seasonal trends of species richness, density, diversity, and redundancy are presented and discussed.The faunal differentiation appeared to be mainly due to the different degree of water exchange, both with marine and continental systems.
Water Flow, Trophic Depletion, and Benthic Macrofauna Impoverishment in a Submarine Cave from the Western Mediterranean
Authors: Zabala Mikel , Riera Tecla , Gili Josep Maria , Barange Manel , Lobo Agustin , Peñuelas Josep 
Published: May 2008

Abstract. Biotic zonation and severe impoverishment of benthic macrofauna are two of the most conspicuous features of submarine caves. The prevailing explanation assumes trophic depletion caused by reduction of water flow. However, no isolation of water was found in the studied Catalan submarine cave, even in the wall microlayer. Fluorescein diffusion was so fast that it was detectable everywhere in the cave already only a few minutes after the injection. The rate of dissolution of plaster spheres was even greater in the cave than in a nearby tunnel – without benthic macrofauna impoverishment – showing a considerable water flow. The oxygen concentration of water in dialysis bags placed at varying distances from the cave walls showed that no wall microlayer gradients were present.Biochemical gradients did not indicate any decrease in food supply. Although photosynthetic pigment concentration generally decreased inside the cave, and although the gradients were not linear but formed different patterns throughout the cave, the BOD5, the POM, the C:N ratio, the [3H]‐thymidine incorporation rate, and the ETS activity were higher in the inner part of the cave. There was an accumulation of detritic material and bacteria in the inner parts that constitute a plausible food supply for benthic macrofauna.If neither water motion nor food supply can be invoked, research into the causes of zonation and disappearence of benthic macrofauna is proposed to be carried out on biotic interactions and behavioural processes.
Primary Production and Growth Dynamics in Posidonia oceanica
Authors: Buia Maria Cristina , Zupo Valerio , Mazzella Lucia 
Published: May 2008

Abstract. Studies on leaf growth and production were performed in two stands, at depths of 5 m and 22m, in the Posidonia oceanica (L.) Delile bed off Lacco Ameno, Ischia (Gulf of Naples). Experiments were carried out in situ from May 1988 to August 1989 at monthly intervals.Leaf growth and production profiles differed in the two stands investigated. Growth rates were higher at 5 m, with a peak in autumn (5.8 mg · shoot‐1· d‐1) and another in March (3.8 mg · shoot‐1· d‐1). At 22 m the maximum rate occurred in May (3.9 mg · shoot‐1· d‐1). These differential growth rates resulted in a delayed maximum leaf surface and biomass at the deep stand, where lower irradiance values and different temperature patterns were also found. The biomass of epiphytic algae showed trends similar to those of leaves; however, there were remarkable differences in the values between the two stations and for the two investigated years.The production data of the present study are compared with those of other reports, and it is shown that growth processes are greatly influenced by physical factors.
Depth and Seasonal Distribution of Some Groups of the Vagile Fauna of thePosidonia oceanicaLeaf Stratum: Structural and Trophic Analyses
Authors: Gambi Maria Cristina , Lorenti Maurizio , Russo Giovanni F. , Scipione Maria Beatrice , Zupo Valerio 
Published: May 2008

Abstract.The taxonomical and trophic structures of the vagile fauna communities of the leaf stratum in aPosidonia oceanicameadow at Ischia (Gulf of Naples, Italy) were investigated at five stations along a depth gradient (1 to 25 m). Sampling was performed in July, November, February, and May. The analyzed groups ‐ polychaetes, molluscs, tanaids, isopods, amphipods, and decapods ‐ exhibited similar distributional trends in all seasons, with coenotic discontinuities occurring at well‐defined depths. The same zonation pattern was produced by feeding‐guild analysis. Eleven trophic groups were identified. The most abundant groups were: Herbivores, which were found mainly at the shallow stations; Herbivores‐deposit feeders, which were widely distributed along the transect; Deposit feeders‐carnivores, found mainly at the deep stations.This study suggests that in thePosidonialeaf stratum, herbivores and herbivores‐deposit feeders, as consumers of epiphytic micro‐ and macroflora and deposited particulate organic matter, play an important role in the energy transfer from producers to higher trophic levels of the system.
Observations on the Spatio‐Temporal Distribution of Crustacean Amphipods in the Fusaro Coastal Lagoon (Central Tyrrhenian Sea, Italy) and Some Notes on Their Presence in Mediterranean Lagoons
Authors: Procaccini Gabriele , Scipione Maria Beatrice 
Published: May 2008

Abstract. The amphipod population of the Fusaro coastal lagoon (Tyrrhenian Sea, Italy) was studied on a spatial‐temporal scale. During a one‐year period, samples were collected on hard and soft bottoms along a transect from the inland to the seaward side of the lagoon. Thirteen species were identified. The dominant taxa included species typical of lagoon environments, such as Corophium insidiosum and Microdeutopus gryllotalpa, and species typical of marine environments yet also inhabiting sheltered or semi‐closed areas, such as Corophium acutum, Ericthonius brasiliensis, and Elasmopus rapax.An inner‐outer gradient was not evident, while a seasonal pattern was recognizable. At the community level, clear differences between the two substrata were not evident because of high algal growth and organogenic detritus on the soft bottoms. The importance of hydrodynamic forces in a euhaline lagoon in selecting amphipod communities ‐ characterized by a typical trophic behaviour and way of life – is discussed. Information on the ecology of the collected species and a list of Mediterranean lagoons where they are present are also provided.
Community Structure of the Subtidal Macroinfauna in an Estuarine Mussel Bed in Southern Chile
Authors: Jaramillo Eduardo , Bertrán Carlos , Bravo Alejandro 
Published: May 2008

Abstract. The mussels Choromytilus chorus and Mytilus chilensis are the most distinctive bivalves of the subtidal soft bottoms of Queule River estuary, southern Chile (ca. 40 °S). In some artificially farmed areas of this estuary, the semi‐buried mussels reach densities as high as 250–300 adult indiv. m‐2. We carried out seasonal (1983) and fortnightly samplings (August 1984 to December 1985) to compare abiotic and biotic characteristics (i. e., macroinfaunal community structure) on bottom areas with and without mussels. Biodeposition within the mussel bed area did not result in organic enrichment of the sediments, a situation which is discussed in relation to the breakdown of mussel biodeposits. During most of this study, organic matter (%) was higher in the sediments of this area versus that without mussels. While the sediments of the mussel and control area were dominated by the same macroinfauna (i.e., polychaetes), that of the mussel area generally had lower abundances, number of species, and diversity indices. Several explanations are presented to account for diminished abundance and diversity values here. These include insufficient substrate for settling larvae, space limitation, and negative effects of sediment characteristics.SummaryMussel biodeposition in a mussel bed area at the Queule River estuary did not result in organic enrichment of the sediments. This may be attributed to the high rate of biodeposit disintegration. During most of the study, the percentage of combustibles (i. e., organic matter) was higher in the mussel bed sediments. This was not necessarily the effect of mussel biodeposit accumulation, since field studies (between‐site comparisons during flood and ebb tides) showed no significant differences between the amount of organic matter in the near fluid, fecal‐rich sediments surface (i. e., 0.5 cm) of the mussel and control area. The macroinfauna of both areas was dominated by the spionid Minuspio chilensis and one capitellid worm. The abundance of the whole macroinfauna and that of the most characteristic taxa peaked during summer‐autumn months. No changes were detected in the community structure of either area (e. g., no changes in the rank of dominant species). The abundances, number of species, and diversity indices were generally lower in the mussel bed area. This condition may be related to negative effects of some sort of mussel‐macroinfauna interaction such as space reduction, adult‐larval interactions, or changes in sediment characteristics.
Benthic Standing Stock and Metabolic Activity in the Bathyal Red Sea from 17°N to 27°N
Authors: Pfannkuche Olaf 
Published: May 2008

Abstract. To study the impact of the gradient of primary production between the southern, central, and northern Red Sea, benthic metabolism and standing stocks were investigated in the axial trough between 17°N and 27°N. Data on sediment chloroplastic pigments, macrofauna and meiofauna abundance, particulate adenylate, protein and carbohydrate biomass, as well as electron transport activity of the sediment community give evidence for an enhanced benthic standing stock and activity in the southern Red Sea south of 18°N; this is related to the increased primary productivity in the area south 16°N. Despite a large primary production only small benthic standing stocks were found in all areas investigated; they are much smaller than in other parts of the world's deep oceans with comparable primary production. The low benthic biomass is caused by two factors: a large proportion of particulate organic carbon is remineralized in the water column, while only a relatively small amount sediments to the sea floor; nearly all sedimented particulate organic matter is respired by the benthic community of the deep Red Sea and only a minute proportion is used for the production of benthic biomass.SummaryEuphotic zone primary production in the Red Sea decreases in a strong gradient from south to north. Highest primary production occurs south of 16°N. Benthic stocks of the Red Sea axial trough from 17°N to 27°N (water depth ≤ 1000 m), depending on the sedimentation rate of particulate organic matter from the euphotic zone, exhibited a corresponding south to north decrease in macro‐ and meiofauna abundance, biomass (particulate total adenylates, proteins, carbohydrates) and activity (ETS‐activity). All data give evidence for an enhanced benthic standing stock and metabolic activity south of 18°N. In contrast to other subtropical regions with comparable surface primary production, the biomass of the Red Sea benthos appears extremely low. This is caused by two factors: a large proportion of the sedimenting particulate organic matter is already remineralized in the water column, while only a small part reaches the sea floor; nearly all sedimented material is respired by the benthic community and only a minute proportion is channelled into biomass production.
Burrowing Behavior, Substratum Preference, and Distribution of Schizaster canaliferus (Echinoidea: Spatangoida) in the Northern Adriatic Sea
Authors: Schinner Gottfried O. 
Published: May 2008

Abstract. Schizaster canaliferus, an endemic Mediterranean spatangoid, is common in the Bay of Piran (Northern Adriatic Sea). The abundance and distribution of this burrowing species is related to sea water depth and particle size distribution of the substrata. Populations are limited to silt/clay sediments in protected sublittoral areas of the Bay, where densities range from 1.9–2.6 individuals · m‐2. Preferred sediments range from medium to fine silt (2–20 μm). Burrowing activity was found to be functional only in fine sediments similar to those naturally inhabited; it did not occur in sandy sediments (>63μm). Burrowing rates were positively correlated with temperature, suggesting that burrowing speeds are greater in summer than winter. S. canaliferus is limited to the upper, oxygenated sediment layers and always burrowed just above the Redox‐Potential‐Discontinuity‐layer (RPD). At field study sites, the RPD ranged from 37 to 45 mm, while echinoid burrowing depths ranged from 30 to 45 mm. Laboratory manipulations of the RPD‐layer indicated that when this layer is displaced to 8cm depth, sea urchins responded by burrowing deeper, settling at depths just above the reoxygenated sediments. Populations of S. canaliferus in the Bay of Piran were randomly dispersed and size frequencies of individuals were unimodal, indicative of regular annual recruitment. 5. canaliferus is highly substrate specific and does not appear to be as widespread in the Adriatic Sea as earlier studies indicated. Its restricted distribution may be indirectly related to morphological constraints of the burrowing apparatus, which limits its occurrence to fine‐grained sediments within protected areas.Summary Schizaster canaliferus has been studied in the Bay of Piran (Northern Adriatic Sea). The abundance and distribution of this burrowing sea‐urchin is related to sea water depth and particle size distribution. Populations were limited to silt/clay sediments in protected sublittoral areas of the Bay. Burrowing activities were found to be functional only in fine sediments, similar to those naturally inhabited. Burrowing rates were positively correlated with temperature. S. canaliferus was limited to the upper, oxygenated sediment layers and always burrowed just above the Redox‐Potential‐Discontinuity‐layer (RPD). S. canaliferus is highly substrate specific and does not appear to be as widespread in the Adriatic Sea as indicated in earlier studies.