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  • 1
    Electronic Resource
    Electronic Resource
    Distribution and composition of particulate organic matter in the Ross Sea (Antarctica) (1993)
    Springer
    Polar biology 13 (1993), S. 525-533 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The biochemical composition and spatial distribution of particulate organic matter (POM) were studied in the Ross Sea (Antarctica) in summer 1989 to assess the quantitative role of organic carbon fractions in the cycling of organic matter in the water column. Large differences in chemical composition were observed between surface and deep layers. The results indicated that, despite large geographical differences, POM was quite homogeneous, of phytoplankton origin and mostly detrital. Different ratios were used to investigate the changes in biochemical composition of particulate organic matter in relation to the ice-melting: C∶N (organic carbon∶organic nitrogen ratio) and C-POM∶POC (sum of carbohydrate, protein and lipid carbon∶total organic carbon ratio) were used to analyse the percentage of refractory organic material. PPRT∶PCHO (protein∶carbohydrate ratio) were used to establish POM “age” and RNA∶DNA ratios as a relative measure of particulate activity; POC∶Chl a and N-PPRT∶Chl a ratios were used to estimate the autotrophic contribution to the suspended particulate organic matter. Despite its low caloric value (5.3 Kcal g POM−1), an high caloric content in the photic layer (1.6 Kcal m−3 of POM and 2.5 Kcal m−3 of POC) was found thus indicating that a large amount of food was available to higher trophic levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236394
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  • 2
    Electronic Resource
    Electronic Resource
    Meiofauna distribution and mesoscale variability in two sites of the Ross Sea (Antarctica) with contrasting food supply (1999)
    Springer
    Polar biology 22 (1999), S. 115-123 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Meiofauna abundance, biomass and community structure were investigated in two comparable deep sites of the Ross Sea (Antarctica) characterized by different trophic and sediment characteristics. Site B (567 m depth, dominated by muddy sediments) and site C (439 m depth, characterized by the presence of calcareous debris and coarse sand) were located at increasing distance from the polynyas and were subject to different inputs of organic material to the seabed. Total meiofauna abundance ranged from 192.0 to 1191.2 ind. 10 cm−2, and total biomass varied between 9.5 and 50.3 μgC 10 cm−2. Meiofauna densities from the Ross Sea are, on average, 2–7 times lower than those reported from other similar deep polar regions and displayed significant differences between the sites. Nematodes dominated the samples at both sites, but their relative significance changed between the sites (80% at site B and 56% at site C), followed by copepods (1.6% and 35% at sites B and C, respectively). Meiofauna composition at site B appeared similar to that reported for deep-sea antarctic or temperate sediments, whereas the composition at site C was similar to that of coastal areas. On a macroscale, the different inputs of utilizable organic material at the two sites were reflected in meiofaunal distribution patterns, indicating that meiofaunal communities from the Ross Sea are dependent on particulate organic matter fluxes from the photic layer and are coupled to pelagic phenomena. Very low microscale variations (i.e. between replicates) in meiofauna density contrasted with large mesoscale variability, which was related to the concentration of the main food indicators (phytopigments, proteins, carbohydrates and lipids).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050398
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  • 3
    Electronic Resource
    Electronic Resource
    Relationship between ectoenzymatic activity and availability of organic substrates (Ross Sea, Antarctica): an experimental approach (1998)
    Springer
    Polar biology 20 (1998), S. 367-376 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Organic matter consumption and decomposition were studied in four experimental systems, having collected different organic substrates in the Ross Sea in December 1994. For the experimental approach selected, processes normally acting on a mixed pool of substances could be separated and the main features of each phenomenon could be focused on. Through the strict relationship between each experimental system and natural conditions shown by organic matter assessment, ectoenzymatic activity trends and their relation with Antarctic water substrates could be described. Through ice melting the water column becomes rich in large pools of substrates, as well as enzyme-producing micro-organisms, capable of quick development. The quantitative predominance of leucine-aminopeptidase throughout the year is well known, but its relative importance seems to decrease when, owing to production events, the environment is enriched with autotrophic- and heterotrophic-derived substances, leading to glycolytic enzymes expression. Thus, ectoenzymatic activity is supposed to be one of the factors responsible for organic matter variations, showing quantitative and qualitative changes depending on substrate availability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050316
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  • 4
    Electronic Resource
    Electronic Resource
    Organic matter composition in coastal sediments at Terra Nova Bay (Ross Sea) during summer 1995 (2000)
    Springer
    Polar biology 23 (2000), S. 288-293 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We illustrate the spatial and vertical distribution of sediment phytopigments and organic matter biochemical composition at Terra Nova Bay (Ross Sea) during summer 1995. Coastal sediments displayed high phytopigments concentrations associated with huge amounts of labile organic matter largely dominated by proteins. This result was opposite to previous observations in the same area. Such comparison suggested that whilst organic matter quantity in the sediments depended upon the vertical input from the water column, temporal changes in its biochemical composition were related to benthic processes. As considerably high concentrations of biopolymeric organic carbon were found even at 6-cm depth and according to the “loss type” functioning of the coastal waters of the Ross Sea, we stress the summer time occurrence in coastal sediments of an important organic matter burial.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050446
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  • 5
    Electronic Resource
    Electronic Resource
    Total and hydrolizable particulate organic matter (carbohydrates, proteins and lipids) at a coastal station in Terra Nova Bay (Ross Sea, Antarctica) (1998)
    Springer
    Polar biology 19 (1998), S. 125-132 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We analysed quantity and quality of particulate organic matter during the austral summer 1994/1995 at a coastal station in Terra Nova Bay (Ross Sea, Antarctica). Our main aims were to investigate the origin and biochemical composition of particulate organic matter (POM), to measure its availability for consumers through the study of its digestible fraction (measured by using different enzymes separately) and to highlight the role of hydrolizable compounds in the organic matter diagenesis in the coastal waters at Terra Nova Bay. Temporal and spatial patterns of chlorophyll-a concentrations were reflected by the particulate organic carbon, nitrogen and total biopolymeric carbon concentrations, suggesting that most POM originated directly from phytoplankton. The most evident feature of POM in the coastal waters at Terra Nova Bay was the dominance of proteins (on average 57% of total biopolymeric particulate carbon), followed by carbohydrates (25%) and lipids (18%). We found that about 30% of the refractory particulate organic carbon (assumed to be present only after the complete exploitation of particulate organic nitrogen) did not originate from biopolymeric carbon (as sum of carbohydrate, protein and lipid carbon). This allows us to suggest the use of the digestible fraction of particulate biopolymeric carbon as a more accurate measure of the food availability of POM for consumers. In Terra Nova Bay coastal waters, most of the particulate protein pool was associated with large phytoplankton cells or phytodetritus. As a result, the protein pool appeared less available (i.e. less digestible) than the one present in oligotrophic waters where, conversely, most particulate organic nitrogen is sequestered into bacteria. The relative low availability of the protein pool, together with the rapid sinking of POM and the low remineralization rates of benthic heterotrophic microbes, are suggested as possible factors in determining the “inefficiency” in organic matter recycling of coastal waters at Terra Nova Bay, which behaves as a “loss type” system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050223
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  • 6
    Electronic Resource
    Electronic Resource
    Origin, biochemical composition and vertical flux of particulate organic matter under the pack ice in Terra Nova Bay (Ross Sea, Antarctica) during late summer 1995 (1999)
    Springer
    Polar biology 22 (1999), S. 124-132 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Water samples and particulate materials settling under the pack ice were collected in an ice-covered area near the Terra Nova Bay Italian Station during late summer 1995, in order to study short-term changes in the biochemical composition of particulate organic matter. At the end of the study period the phytoplankton biomass increase (up to 〉3.0 μg chlorophyll-a l−1) was probably related to the intrusion under the pack ice of chlorophylls-enriched surface waters coming from the near ice-free area. Such increase was associated also with a notable increase in particulate organic matter concentrations, as well as in particulate organic matter vertical fluxes (up to 〉100 mg C m−2 day−1). Proteins were the most abundant biochemical class of particulate organic matter (on average about 49%), followed by lipids (29%) and carbohydrates (22%). By contrast, organic matter collected in the sediment trap was characterized by the dominance of lipids (about 55% of the total biopolymeric carbon flux) over carbohydrates (28%) and proteins (17%). The hydrolizable particulate biopolymeric carbon accounted for about 23% of total biopolymeric carbon. This value was about one-half of that found in ice-free waters, suggesting that the suspended particulate organic material under the pack ice was less digestible than in ice-free waters or was already partially digested. Despite this, and the decay of labile organic compounds in the sediment trap during the deployment, material settling towards the sea bottom under the pack ice in Terra Nova Bay, owing to its high lipid content, might represent an important high-quality food source for benthic consumers. Finally, assuming as possible the intrusion under sea ice of primary organic matter-enriched waters, we hypothesize the occurrence of a “fertilization” effect deriving from ice-melting areas towards under-ice waters, supplying the latter with an additional rate of primary organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050399
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  • 7
    Electronic Resource
    Electronic Resource
    Composition of organic matter in sediments facing a river estuary (Tyrrhenian Sea): relationships with bacteria and microphytobenthic biomass (1994)
    Springer
    Hydrobiologia 277 (1994), S. 71-84 
    Details
    ISSN: 1573-5117
    Keywords: benthic bacteria ; organic matter composition ; photosynthetic pigments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationships between the biochemical composition of sediment organic matter and bacteria and microphytobenthic biomass distribution, were investigated along the coast of Northern Tuscany (Tyrrhenian Sea). Organic matter appeared to be of highly refractory composition. Among the three main biochemical classes, proteins were the major component (0.96 mg g-1 sediment d.w.) followed by total carbohydrates (0.81 mg g-1 sediment d.w.) and lipids (8.1 µg g-1 sediment d.w.). Bacterial number in surface sediments (0–2 cm) ranged from 1.7 to 24.5 × 108 cells g-1 of sediment dry weight showing a strong decrease with sediment depth. In surface sediments, significant correlations were found between bacterial biomass and protein concentration. Bacterial activity (measured by the frequency of dividing cells) was significantly related to lipid concentration. Bacterial and microphytobenthic biomass accounted for 3.1 and 18.1% respectively of the sediment organic carbon. In surface sediments bacterial lipids accounted, on average, for 27 % of total lipids, whereas bacterial proteins and carbohydrates accounted for 2.5 and 0.5% of total proteins and carbohydrates, respectively. The benthic degradation process indicated that lipids were a highly degradable compound (about 35% in the top 10 cm). Carbohydrate decreased for 25.6% in the top 10 cm, whereas proteins increased with depth, thus indicating that this compound may resist to diagenetic decomposition. These data suggest that specific organic compounds need to be measured rather than bulk carbon and nitrogen measurements in order to relate microbial biomass to the quality of organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016755
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  • 8
    Electronic Resource
    Electronic Resource
    Biochemical composition of particulate organic matter and bacterial dynamics at the sediment–water interface in a Mediterranean seagrass system (1997)
    Springer
    Hydrobiologia 363 (1997), S. 241-251 
    Details
    ISSN: 1573-5117
    Keywords: particulate organic matter composition ; bacteria ; sediment-waterinterface ; Posidonia oceanica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seagrass Posidonia oceanica is the most productive system of theMediterranean Sea. In order to gather information on the temporal andspatial variability of the suspended particulate matter in relation tobacterial dynamics, water samples were collected at 10 cm above thesediments over a period of 13 months in the Prelo Bay (Ligurian Sea, NWMediterranean). Measurements of seston concentration, as well as theelemental (POC and PON) and biochemical composition (lipids, proteins,carbohydrates and nucleic acids) of particulate matter were carried out toassess the origin, composition and bacterial contribution to the foodpotentially available in the seagrass system to consumers. Lipids andproteins were the main biochemical classes of organic compounds, followed bycarbohydrates. Despite the highly refractory composition of the seagrassleaves, particulate organic matter was mostly composed of labile compounds(69.9% of POC). POM temporal patterns were controlled by currentspeed at the sediment–water interface that resuspended only smallparticles largely colonised by bacteria after an intensive process offractionation and aging. In the seagrass system, the POM appears to bedominated by bacteria (density ranging from 0.7 to 2.5×109 cells l™1, representing more than48.3% of POC and 68.7% of the biopolymeric carbon, as the sumof lipid, protein and carbohydrate carbon). This feature was characteristicof the seagrass system since much lower bacterial densities were foundoutside the Posidonia meadow. Bacteria were negatively correlated with theconcentration of nitrite and nitrate suggesting a selective utilisation ofinorganic nutrients to support their growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003177822660
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  • 9
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    Seasonal changes in labile organic matter composition on the continental shelf and bathyal sediments of the Cretan Sea
    PANGAEA
    In:  Supplement to: Danovaro, Roberto; Marrale, Daniela; Dell'Anno, Antonio; Della Croce, Norberto; Tselepides, Anastasios; Fabiano, Mauro (2000): Bacterial response to seasonal changes in labile organic matter composition on the continental shelf and bathyal sediments of the Cretan Sea. Progress in Oceanography, 46/2-4, 345-366, https://doi.org/10.1016/S0079-6611(00)00025-2
    Details
    Publication Date: 2023-05-12
    Description: Bacterial abundance, biomass and cell size were studied in the oligotrophic sediments of the Cretan Sea (Eastern Mediterranean), in order to investigate their response to the seasonal varying organic matter (OM) inputs. Sediment samples were collected on a seasonal basis along a transect of seven stations (ranging from 40 to 1570 m depth) using a multiple-corer. Bacterial parameters were related to changes in chloroplastic pigment equivalents (CPE), the biochemical composition (proteins, lipids, carbohydrates) of the sedimentary organic matter and the OM flux measured at a fixed station over the deep basin (1570 m depth). The sediments of the Cretan Sea represent a nutrient depleted ecosystem characterised by a poor quality organic matter. All sedimentary organic compounds were found to vary seasonally, and changes were more evident on the continental shelf than in deeper sediments. Bacterial abundance and biomass in the sediments of the Cretan Sea (ranging from 1.02 to 4.59 * 10**8 cells/g equivalent to 8.7 and 38.7 µgC/g) were quite high and their distribution appeared to be closely related to the input of fresh organic material. Bacterial abundance and biomass were sensitive to changes in nutrient availability, which also controls the average cell size and the frequency of dividing cells. Bacterial abundance increased up to 3-fold between August '94 and February '95 in response to the increased amount of sedimentary proteins and CPE, indicating that benthic bacteria were constrained more by changes in quality rather than the quantity of the sedimentary organic material. Bacterial responses to the food inputs were clearly detectable down to 10 cm depth. The distribution of labile organic compounds in the sediments appeared to influence the vertical patterns of bacterial abundance and biomass. Cell size decreased significantly with water depth. Bacterial abundance and biomass were characterised by clear seasonal changes in response to seasonal OM pulses. The strong coupling between protein flux and bacterial biomass together with the strong bacterial dominance over the total biomass suggest that the major part of the carbon flow was channelled through the bacteria and the benthic microbial loop.
    Keywords: Cretan Sea; D1-D7; HERMES; Hotspot Ecosystem Research on the Margins of European Seas
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 10
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    Biogeochemistry of sediments in the Aegean Sea
    PANGAEA
    In:  Supplement to: Danovaro, Roberto; Marrale, Daniela; Della Croce, Norberto; Parodi, P; Fabiano, Mauro (1999): Biochemical composition of sedimentary organic matter and bacterial distribution in the Aegean Sea: Trophic state and pelagic-benthic coupling. Journal of Sea Research, 42/2, 117-129, https://doi.org/10.1016/S1385-1101(99)00024-6
    Details
    Publication Date: 2023-05-12
    Description: Biochemical composition of sedimentary organic matter (OM), vertical fluxes and bacterial distribution were studied at 15 stations (95-2270 m depth) in the Aegean Sea during spring and summer. Downward fluxes of labile OM were significantly higher in the northern than in the southern part and were higher in summer than in spring. Primary inputs of OM were not related to sedimentary OM concentrations, which had highest values in summer. Sedimentary chlorophyll-a concentrations were similar in the northern and southern parts. Carbohydrates, the main component of sedimentary OM, were about 1.2 times higher in the southern part than in the northern, without significant temporal changes. Total proteins were higher in summer and about double in the northern part. Sedimentary proteins appeared more dependent upon the downward flux of phytopigment than of proteins. Sedimentary OM was characterised by a relatively large fraction of soluble compounds and showed better quality in the northern part. The lack of a depth-related pattern in sedimentary OM and the similar concentrations in the two areas suggest that differences in sedimentary OM quality in the Aegean basin are dependent on system productivity; the bulk of sedimentary OM is largely conservative. Sedimentary bacterial density was about double in the northern part and higher in spring than in summer, but bacterial size was about three times higher in summer, resulting in a larger bacterial biomass in summer. Bacterial density was coupled with total and protein fluxes, indicating a rapid bacterial response to pelagic production. Bacterial biomass was significantly correlated with sedimentary protein and phytopigment concentrations, indicating a clear response to accumulation of labile OM in the sediments. In all cases bacteria accounted for 〈5% of the organic C and N pools. The efficiency of benthic bacteria in exploiting protein pools, estimated as amounts of protein available per unit bacterial biomass, indicates a constant ratio of about 70 µg proteins/µg C. This suggests a similar bacterial efficiency all over the area studied, unaffected by different trophic conditions.
    Keywords: Aegean Sea; MSB-MNB; SESAME; Southern European Seas: Assessing and Modelling Ecosystem Changes
    Type: Dataset
    Format: application/zip, 2 datasets
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