scholarly journals Characteristics of the Biochemical Composition and Bioavailability of Phytoplankton-Derived Particulate Organic Matter in the Chukchi Sea, Arctic

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2355
Author(s):  
Bo Kim ◽  
Jinyoung Jung ◽  
Youngju Lee ◽  
Kyoung-Ho Cho ◽  
Jong-Ku Gal ◽  
...  
Keyword(s):  
Organic Matter ◽  
Enzymatic Hydrolysis ◽  
Particulate Organic Matter ◽  
Biochemical Composition ◽  
Chukchi Sea ◽  
Total Concentration ◽  
Trophic Levels ◽  
Food Utilization ◽  
Positive Effects ◽  
Bioavailable Fraction

Analysis of the biochemical composition (carbohydrates, CHO; proteins, PRT; lipids, LIP) of particulate organic matter (POM, mainly phytoplankton) is used to assess trophic states, and the quantity of food material is generally assessed to determine bioavailability; however, bioavailability is reduced or changed by enzymatic hydrolysis. Here, we investigated the current trophic state and bioavailability of phytoplankton in the Chukchi Sea (including the Chukchi Borderland) during the summer of 2017. Based on a cluster analysis, our 12 stations were divided into three groups: the southern, middle, and northern parts of the Chukchi Sea. A principal component analysis (PCA) revealed that relatively nutrient-rich and high-temperature waters in the southern part of the Chukchi Sea enhanced the microphytoplankton biomass, while picophytoplankton were linked to a high contribution of meltwater derived from sea ice melting in the northern part of the sea. The total PRT accounted for 41.8% (±7.5%) of the POM in the southern part of the sea, and this contribution was higher than those in the middle (26.5 ± 7.5%) and northern (26.5 ± 10.6%) parts, whereas the CHO accounted for more than half of the total POM in the northern parts. As determined by enzymatic hydrolysis, LIP were more rapidly mineralized in the southern part of the Chukchi Sea, whereas CHO were largely used as source of energy for higher trophic levels in the northern part of the Chukchi Sea. Specifically, the bioavailable fraction of POM in the northern part of the Chukchi Sea was higher than it was in the other parts. The findings indicate that increasing meltwater and a low nutrient supply lead to smaller cell sizes of phytoplankton and their taxa (flagellate and green algae) with more CHO and a negative effect on the total concentration of POM. However, in terms of bioavailability (food utilization), which determines the rate at which digested food is used by consumers, potentially available food could have positive effects on ecosystem functioning.

scholarly journals Quantity and biochemical composition of particulate organic matter in a highly trawled area (Thermaikos Gulf, Eastern Mediterranean Sea)

2015 ◽  
Vol 6 (1/2) ◽  
Author(s):  
Antonio Pusceddu ◽  
Silvia Bianchelli ◽  
Roberto Danovaro
Keyword(s):  
Organic Matter ◽  
Mediterranean Sea ◽  
Water Column ◽  
Particulate Organic Matter ◽  
Biochemical Composition ◽  
Eastern Mediterranean ◽  
Sediment Resuspension ◽  
Natural Sediment ◽  
Bottom Trawling ◽  
Bioavailable Fraction

Bottom trawling represents nowadays one of the most severe anthropogenic disturbances at sea, and determines large impacts on benthic communities and processes. Bottom trawling determines also local sediment resuspension and the effects of the injection of large amounts of surface sediments into the water column have been repeatedly investigated. Few studies have assessed the consequences of sediment resuspension caused by bottom trawling on the quantity, biochemical composition and bioavailability of suspended organic particles and how these eventually rival those exerted by natural storms. To provide insights on this poorly addressed issue, we investigated concentrations and biochemical composition of total and enzymatically digestible pools of particulate organic matter (POM) in the Thermaikos Gulf (Mediterranean Sea) under calm sea conditions, during intensive trawling activities, and after a severe storm. We show here that sediment resuspension caused by trawling can cause large effects on POM quantity, biochemical composition and bioavailability. Both during trawling and after the storm, the relative importance of the carbohydrate pools increased (in the upper water column) and the total lipid concentrations decreased (in the intermediate and bottom layers) when compared to values measured during calm conditions. These results would suggest that bottom trawling could inject in the upper water column POM pools more refractory in nature (<em>e.g</em>., carbohydrates) than those present in calm or after-storm conditions. By contrast, we show also that the bioavailable fraction of biopolymeric C increased significantly during trawling in the upper water column of the shallowest stations and in the bottom water column layer of the deepest ones. These results provide evidence that bottom trawling can influence the overall trophic status of coastal waters, exerting effects similar or stronger than those caused by natural storms, though of variable amplitude depending on the water depth. Since bottom trawling is carried out worldwide and natural storms at sea can be frequent and intense, we claim for the need of assessing new adapting management strategies of bottom trawling in order to mitigate the synergistic impacts of anthropogenic and natural sediment resuspension on coastal biogeochemical cycles.

scholarly journals Sink or link? The bacterial role in benthic carbon cycling in the Arabian Sea's oxygen minimum zone

2013 ◽  
Vol 10 (11) ◽  
pp. 6879-6891 ◽  
Author(s):  
L. Pozzato ◽  
D. Van Oevelen ◽  
L. Moodley ◽  
K. Soetaert ◽  
J. J. Middelburg
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Particulate Organic Matter ◽  
Experimental Period ◽  
Oxygen Minimum Zone ◽  
Trophic Levels ◽  
Isotope Tracer ◽  
Oxygen Conditions ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. The bacterial loop, the consumption of dissolved organic matter (DOM) by bacteria and subsequent transfer of bacterial carbon to higher trophic levels, plays a prominent role in pelagic food webs. However, its role in sedimentary ecosystems is not well documented. Here we present the results of isotope tracer experiments performed under in situ oxygen conditions in sediments from inside and outside the Arabian Sea's oxygen minimum zone (OMZ) to study the importance of the microbial loop in this setting. Particulate organic matter, added as phytodetritus, was processed by bacteria, protozoa and metazoans, while dissolved organic matter was processed only by bacteria and there was very little, if any, transfer to higher trophic levels within the 7 day experimental period. This lack of significant transfer of bacterial-derived carbon to metazoan consumers indicates that the bacterial loop is rather inefficient, in sediments both inside and outside the OMZ. Moreover, metazoans directly consumed labile particulate organic matter resources and thus competed with bacteria for phytodetritus.

Elucidating trophic pathways of the most abundant fish larvae in northern Patagonia using δ13C and δ15N isotopes

2020 ◽  
Vol 650 ◽  
pp. 253-267
Author(s):  
A Bernal Bajo ◽  
LR Castro ◽  
D Costalago
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Fish Larvae ◽  
Trophic Position ◽  
Trophic Levels ◽  
Feeding Strategies ◽  
Late Winter ◽  
Terrestrial Organic Matter ◽  
Δ13c And Δ15n ◽  
Northern Patagonia

The alternation of the classic and microbial food-webs in spring and winter, respectively, and the trespass towards higher trophic levels represented by fish early stages, are not well understood in Patagonia. These trophic routes were investigated in the inner Sea of Chiloe, an estuary of high ecological relevance in northern Patagonia. The isotopic values of δ13C and δ15N of ichthyoplankton and particulate organic matter were analyzed in late winter and spring 2017 to evaluate whether seasonal changes (e.g. in the composition of the freshwater discharge) were reflected in the isotopic signals of fish larvae. For this purpose, larvae of dominant fish species with contrasting feeding strategies were collected up to 100 m depth. The inshore zone of northern Patagonia was characterized by a dominance of marine carbon production, with increasing input of terrestrial organic matter during winter. δ13C values < -25 ‰ at the outermost estuary stations indicated the influence of allochthonous carbon exported from the inshore area in spring. The δ13C-larval signature of the species of the lightfish Maurolicus parvipinnis, the pipefish Leptonotus blainvilleanus, and the rockfish Sebastes oculatus followed the isotopic signature of the particulate organic matter in both seasons, at inshore and the exchange (outer) zone. Food partitioning was detected between species, with Merluccius spp. at the highest trophic position and L. blainvilleanus at the lowest. The fish larval community reached more diverse and higher δ15N values in winter, when larvae likely fed on prey items of higher trophic level, or instead when the food-web was partly sustained by microbial sources. Our results showed seasonal variations in δ13C values, suggesting differences in the source of organic carbon incorporated by the studied fish larvae. Moreover, trophic plasticity at larval stages may be an important characteristic of this type of estuarine environment.

scholarly journals The effects of different environmental factors on the biochemical composition of particulate organic matter in Gwangyang Bay, South Korea

2017 ◽  
Vol 14 (7) ◽  
pp. 1903-1917 ◽  
Author(s):  
Jang Han Lee ◽  
Dabin Lee ◽  
Jae Joong Kang ◽  
Hui Tae Joo ◽  
Jae Hyung Lee ◽  
...  
Keyword(s):  
Organic Matter ◽  
Environmental Factors ◽  
South Korea ◽  
Particulate Organic Matter ◽  
Biochemical Composition ◽  
Inorganic Nitrogen ◽  
Marine Ecosystem ◽  
Nitrogen Loading ◽  
Food Material ◽  
Gwangyang Bay

Abstract. The biochemical composition of particulate organic matter (POM) produced through phytoplankton photosynthesis is important in determining food quality for planktonic consumers as well as the physiological conditions of phytoplankton. Major environmental factors controlling the biochemical composition were seasonally investigated in Gwangyang Bay, South Korea, which has only natural conditions (e.g., no artificial dams). Water samples for the biochemical compositions were obtained from three different light depths (100, 30, and 1 %) mainly at three sites in Gwangyang Bay from April 2012 to April 2013. Different biochemical classes (carbohydrates, CHO; proteins, PRT; and lipids, LIP) were extracted, and then the concentrations were determined by the optical density measured with a spectrophotometer. The highest and lowest PRT compositions among the three biochemical classes were found in April 2012 (58.0 %) and August 2012 (21.2 %), whereas the highest and lowest LIP compositions were found in August 2012 (49.0 %) and April 2012 (24.8 %), respectively. The CHO composition was recorded as high in January 2013 and remained above 25 % during the study period. The calorific contents of the food material (FM) ranged from 1.0 to 6.1 Kcal m−3 (annual average ± SD  =  2.8 ± 1.1 Kcal m−3). Based on a Pearson's correlation coefficient analysis, a major governing factor in the biochemical composition of POM was dissolved inorganic nitrogen loading from the river input in Gwangyang Bay. In conclusion, a relatively larger amount of FM and the higher calorific contents of POM found in this study compared to other regions reflected good nutritive conditions for sustaining productive shellfish and fish populations in Gwangyang Bay. Continuous observations are needed to monitor the marine ecosystem response to potential environmental perturbations in Gwangyang Bay.

scholarly journals Temporal changes in the biochemical composition of particulate organic matter sedimentation in the Bay of Banyuls-sur-Mer

1998 ◽  
Vol 21 (6) ◽  
pp. 783-792 ◽  
Author(s):  
Antoine Grémare ◽  
Jean-Michel Amouroux ◽  
François Charles ◽  
Laurence Medernach ◽  
Esther Jordana ◽  
...  
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Biochemical Composition ◽  
Temporal Changes
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