scholarly journals FLUCTUATIONS OF THE BENTHIC FAUNA AND DECOMPOSITION ABILITY FOR THE ORGANIC MATTER ON THE OYSTERSHELL-OVERLAID SEA FLOOR IN A CLOSED SEA AREA, BISAN STRAIT.

2017 ◽  
Vol 73 (2) ◽  
pp. I_893-I_898
Author(s):  
Shuzo TAKAGI ◽  
Masayoshi KONDOH ◽  
Hiroshi HAYASHI ◽  
Shinya FUJISAWA ◽  
Satoru KAMURA
Keyword(s):  
Organic Matter ◽  
Benthic Fauna ◽  
Sea Floor ◽  
Sea Area

Gametogenesis and the reproductive cycle in the deep-sea anemone Paracalliactis stephensoni (Cnidaria: Actiniaria)

1990 ◽  
Vol 70 (1) ◽  
pp. 163-172 ◽  
Author(s):  
Michel Praet-Van
Keyword(s):  
Organic Matter ◽  
Shallow Water ◽  
Deep Sea ◽  
Phytoplankton Bloom ◽  
Sea Anemone ◽  
Bay Of Biscay ◽  
Sea Anemones ◽  
Spring Phytoplankton Bloom ◽  
Sea Floor ◽  
Ultrastructural Investigation

This ultrastructural investigation of gametogenesis in a deep-sea anemone of the Bay of Biscay trawled around 2000 m depth, contributes to the knowledge of biology and strategy of reproduction of deep-sea benthos.This sea anemone is dioecious. The sperm appears very similar to those of shallow water sea anemones of the genus, Calliactis. The ultrastructural investigation of oogenesis allows the characteristics of the stages of previtellogenesis and vitellogenesis to be defined. The latter begins with a period of lipogenesis correlated with the formation of a trophonema. Mature oocytes measure up to 180 (im in diameter. Study of spermatogenesis and oogenesis reveals that spawning occurs in April/May. In males, the main area of testicular cysts, full of sperm, reaches maximal development from March to May and, in females, the percentage of mature oocytes decreases from 33% in April to 1% in May.Spawning may be induced by the advent in the deep-sea of the products of the spring phytoplankton bloom. This period of spawning, during the increased deposition of organic matter to the deep-sea floor, may be an advantageous strategy for early development of Paracalliactis.

Spatial and seasonal variation in dissolved silica benthic fluxes in the shallow zones of the southern Baltic Sea

2021 ◽  
Author(s):  
Zuzanna Borawska ◽  
Beata Szymczycha ◽  
Marc J. Silberberger ◽  
Marta Szczepanek ◽  
Katarzyna Koziorowska-Makuch ◽  
...  
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Environmental Conditions ◽  
Benthic Fauna ◽  
Benthic Fluxes ◽  
Dissolved Silica ◽  
Szczecin Lagoon ◽  
Southern Baltic Sea ◽  
Puck Bay

<p>Dissolved silica (DSi) is an important macronutrient in the marine environment, necessary for growth of many aquatic organisms. Yet, DSi marine cycle is still not fully recognized, especially in dynamic, coastal zones. Although DSi is mainly transported to the sea by rivers, benthic fluxes of DSi, which originate from dissolution of the siliceous remains in the sediments, can also represent an important source of bioavailable silicon in the ocean. Benthic DSi fluxes are mainly powered by diffusion, but their rates are strongly shaped by the benthic fauna. Still, the role of benthos in these processes is not fully recognized. The main goal of this study was to investigate how various environmental factors and benthic fauna may shape the coastal cycle of Si in coastal environments during different seasons.</p><p>Our study was conducted in the shallow coastal ecosystems of the southern Baltic Sea characterized by contrasting environmental conditions: shallow, brackish and enclosed Szczecin Lagoon (Oder river estuary), dynamic open waters near Łeba with relatively low anthropogenic influence, enclosed Puck Bay and Vistula prodelta. We investigated both shore ecosystems (app. 0.5 m depth) and deeper areas (from 6 up to 60 m depth). DSi concentrations in the bottom waters and environmental characteristics (T, S, O<sub>2</sub>, sediment organic matter) were investigated at 6 stations, during three seasons (winter, spring and autumn) in years 2019-2020 with s/y Oceania (IOPAN) and directly from the shore. Additionally, samples from shore stations were collected during summer. DSi benthic fluxes were determined at each station by performing <em>ex situ</em> incubations of sediment cores (n = 4-5) with natural benthic assemblages. The benthic organisms in studied cores were collected, identified, counted, and weighed.</p><p>The lowest fluxes were measured at sandy stations while highest return fluxes were observed at muddy sites. High variability in DSi benthic fluxes along studied localities was observed, ranging from -1.11 mmol d<sup>-1</sup>m<sup>-2</sup> in summer at shore station in the Puck Bay and up to 6.79 mmol d<sup>-1</sup>m<sup>-2</sup> in Szczecin Lagoon in autumn. We used  Gaussian Generalized Linear Models (GLMs) to estimate the role of environmental conditions, benthic fauna characteristics  and interactions among them in the variability of DSi benthic flux across studied localities. The most important predictors for the fluxes were all pair-wise interactions of temperature, total organic carbon, the C/N molar ratio, and the density of benthic macrofauna. Both interaction terms that included C/N ratio, a measure of organic matter quality (i.e. low C/N ratio indicates higher quality), were associated with increased DSi uptake by the sediment. Further, the interaction term between T and benthic marcofauna density was also linked to negative benthic fluxes of DSi. In contrast, the interaction of T and TOC caused a strong increase in DSi return fluxes.</p>

scholarly journals Assessment of the quality and quantity of organic matter in the Rufiji mangrove surface sediments using biochemical composition

2021 ◽  
Vol 47 (2) ◽  
pp. 800-811
Author(s):  
Daniel A. Shilla
Keyword(s):  
Organic Matter ◽  
Biochemical Composition ◽  
Stable Carbon Isotope ◽  
Benthic Fauna ◽  
Mangrove Sediments ◽  
Labile Organic Matter ◽  
Spatial Changes ◽  
Mangrove System ◽  
Total Carbohydrates ◽  
Biopolymeric Carbon

This study was carried out to investigate spatial changes in the quality and quantity of sedimentary organic matter in the Rufiji mangrove system, Tanzania. Sediment samples were collected from three sampling sites. Total organic matter in mangrove sediments ranged from 7.28 ± 2.02% to 10.58 ± 1.34%. Protein concentrations varied from 1,145.33 ± 20.33 μg/g to 2,747.50 ± 25.14 μg/g in the mangrove sediments. Total carbohydrates, lipids and biopolymeric carbon in mangrove sediments ranged between 1,110.50 ± 16.31 μg/g and 1,914.17 ± 27.79 μg/g, 1,436.50 ± 24.13 μg/g and 6,373.50 ± 25.79 μg/g, and 4,496 μg C/g and 10,231.50 μg C/g, respectively. Tannins and lignins in mangrove sediments varied from 817.67 ± 12.97 μg/g to 1786.50 ± 30.74 μg/g, while stable carbon isotope (δ13C) in Rufiji mangrove sediments ranged between –26.64 ± 0.10 ‰ and –25.48 ± 0.13 ‰. Higher protein:carbohydrate (PRT:CHO) at station 3 indicated the presence of freshly deposited organic matter. The high lipid:carbohydrate (LPD:CHO) ratios observed in the Rufiji mangrove systems pointed towards the high quality of labile organic matter which supports benthic fauna. PCA revealed the association of variables and their distribution on trends across sites of the Rufiji mangrove system. Keywords: Organic matter, biochemical composition, Rufiji, mangroves, sediments  

scholarly journals Benthic Foraminiferal Response to the Millennial-Scale Variations in Monsoon-Driven Productivity and Deep-Water Oxygenation in the Western Bay of Bengal During the Last 45 ka

2021 ◽  
Vol 8 ◽  
Author(s):  
Komal Verma ◽  
Harshit Singh ◽  
Arun Deo Singh ◽  
Pradyumna Singh ◽  
Rajeev Kumar Satpathy ◽  
...  
Keyword(s):  
Organic Matter ◽  
Deep Water ◽  
Sea Floor ◽  
The Core ◽  
Sea Bottom ◽  
Core Site ◽  
Bottom Waters ◽  
Western Bay Of Bengal ◽  
Matter Flux ◽  
Millennial Scale

In this study, we presented a high-resolution benthic foraminiferal assemblage record from the western Bay of Bengal (BoB) (off Krishna–Godavari Basin) showing millennial-scale variations during the last 45 ka. We studied temporal variations in benthic foraminiferal assemblages (relative abundances of ecologically sensitive groups/species, microhabitat categories, and morphogroups) to infer past changes in sea bottom environment and to understand how monsoon induced primary productivity-driven organic matter export flux and externally sourced deep-water masses impacted the deep-sea environment at the core site. Our records reveal a strong coupling between surface productivity and benthic environment on glacial/interglacial and millennial scale in concert with Northern Hemisphere climate events. Faunal data suggest a relatively oxic environment when the organic matter flux to the sea floor was low due to low primary production during intensified summer monsoon attributing surface water stratification and less nutrient availability in the mixed layer. Furthermore, records of oxygen-sensitive benthic taxa (low-oxygen vs. high-oxygen benthics) indicate that changes in deep-water circulation combined with the primary productivity-driven organic matter flux modulated the sea bottom oxygen condition over the last 45 ka. We suggest that the bottom water at the core site was well-ventilated during the Holocene (except for the period since 3 ka) compared with the late glacial period. At the millennial timescale, our faunal proxy records suggest relatively oxygen-poor condition at the sea floor during the intervals corresponding to the cold stadials and North Atlantic Heinrich events (H1, H2, H3, and H4) compared with the Dansgaard/Oeschger (D-O) warm interstadials. The study further reveals oxygen-poor bottom waters during the last glacial maximum (LGM, 19–22 ka) which is more pronounced during 21–22 ka. A major shift in sea bottom condition from an oxygenated bottom water during the warm Bølling–Allerød (B/A) (between 13 and 15 ka) to the oxygen-depleted condition during the cold Younger Dryas (YD) period (between 10.5 and 13 ka) is noticed. It is likely that the enhanced inflow of North Atlantic Deep Water (NADW) to BoB would have ventilated bottom waters at the core site during the Holocene, B/A event, and probably during the D-O interstadials of marine isotope stage (MIS) 3.

Transportation of organic matter to the sea floor by carrion falls of the giant jellyfish Nemopilema nomurai in the Sea of Japan

2007 ◽  
Vol 153 (3) ◽  
pp. 311-317 ◽  
Author(s):  
Jun Yamamoto ◽  
Miyuki Hirose ◽  
Tetsuya Ohtani ◽  
Katashi Sugimoto ◽  
Kazue Hirase ◽  
...  
Keyword(s):  
Organic Matter ◽  
Sea Of Japan ◽  
The Sea Of Japan ◽  
Nemopilema Nomurai ◽  
Sea Floor ◽  
Giant Jellyfish

Transformations of biogenic particles during sedimentation in the northeastern Atlantic

1995 ◽  
Vol 348 (1324) ◽  
pp. 179-189 ◽  
Keyword(s):  
Organic Matter ◽  
Deep Sea ◽  
Vertical Flux ◽  
Biological Pump ◽  
Sea Floor ◽  
The North ◽  
Sea Bed ◽  
Attached Bacteria ◽  
North Eastern ◽  
Break Up

The vertical flux and transformation of biogenic particles are im portant processes in the oceanic carbon cycle. Changes in the magnitude of the biological pump can occur in the north eastern Atlantic on both a seasonal and interannual basis. For example, seasonal variations in vertical flux at 47° N 20° W are linked to seasonal ocean productivity variations such as the spring bloom. The size and organic and inorganic content of phytoplankton species, their development and succession also play a role in the scale and composition of the biological pump. The majority of flux is in the form of fast sinking aggregates. Bacteria and transparent exopolymer particle production by phytoplankton have been implicated in aggregate production and mass flux events. Zooplankton grazing and faecal pellet production, their size and composition and extent of their vertical migration also influence the magnitude of vertical flux. Aggregates are formed in the upper ocean, often reaching a maximum concentration just below the seasonal thermocline and can be a food resource to mesozooplankton as well as to the high concentrations of attached bacteria and protozoa. Attached bacteria remineralize and solubilize the aggregate particulate organic carbon. The degree of particle solubilization is likely to be affected by factors controlling enzyme activity and production, for example temperature, pressure or concentration of specific organic molecules, all of which may change during sinking. Attached bacterial growth is greatest on particulate organic matter collected at 500 m which is the depth where studies of 210 Po reveal that there is greatest break-up of rapidly sinking particles. Break-up of particles by feeding zooplankton can also occur. The fraction of sinking POC lost between 150-3100 m at one station in the north eastern Atlantic could supply about 90% of the bacterial carbon demand. Some larger, faster sinking aggregates escape solubilization and disaggregation in the upper 1000 m and arrive in the deep ocean and on the deep-sea bed. Seasonally varying rates of sedimentation are reflected at the deep-sea floor by deposition of phytodetrital material in summer. Approximately 2-4% of surface water primary production reaches the sea floor in 4500 m depth at 47° N 20° W after a sedimentation time of about 4-6 weeks. In this region, concentrations of chloroplastic pigments increased in summer by an order of magnitude, whereas seasonal changes in activity or biomass parameters were smaller. Breakdown of the generally strongly degraded organic matter deposited on deep-sea sediments is mainly accomplished by bacteria. Rates of degradation and efficiency of biomass production depend largely on the proportion of biologically labile material which decreases with advancing decay. It is likely that different levels of organic matter deposition influence the bioturbation rates of larger benthos, which has an effect on transport processes within the sediment and presumably also on microbial degradation rates.

Sign in / Sign up

Export Citation Format

Share Document