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 Biogeochemical characterization of the riverine particulate organic matter transferred to the NW Mediterranean Sea

2014 ◽  
Vol 11 (1) ◽  
pp. 157-172 ◽  
Author(s):  
M. Higueras ◽  
P. Kerhervé ◽  
A. Sanchez-Vidal ◽  
A. Calafat ◽  
W. Ludwig ◽  
...  
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
High Water ◽  
Terrestrial Organic Matter ◽  
Rhône River ◽  
Δ13c And Δ15n ◽  
Coastal Rivers ◽  
Rhone River ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

Abstract. A large amount of terrestrial organic matter is annually delivered by rivers to the continental shelf, where this material is either degraded, buried or transferred to the deep sea by hydrodynamic processes such as storms. The relative amount of terrestrial organic matter in the marine sediments is often determined by analysing the stable isotopes (δ13C and δ15N) and the C / N ratio of organic matter because the various particulate organic matter (POM) sources have distinct isotopic compositions. With the objective to refine and better interpret POM sources in the marine environment, we have characterized monthly terrestrial POM delivered by eight rivers discharging to the NW Mediterranean Sea: the Rhône, Hérault, Orb, Aude, Têt, Fluvià, Ter and Tordera rivers. These rivers were simultaneously sampled from November 2008 to December 2009 and the concentrations of total suspended matter (TSM), particulate organic carbon (POC) and nitrogen (PN), as well as their stable isotopic ratios (δ13C and δ15N) were determined. During the survey, three rainstorm events with winds coming from the E–NE and the S–SE impacted the NW Mediterranean. Depending on the direction of incoming winds, the fluvial response (amount of water discharge and TSM) was different. Rivers draining the Alps (Rhône River) and Central Massif (Hérault, Orb, and Aude rivers) were mostly impacted by rainstorms associated with winds coming from the S–SE, while rivers draining the Pyrenees (Têt, Fluvià, and Ter rivers) and the Montseny Massif (Tordera River) were impacted by rainstorms associated with winds coming from the E–NE. In addition, the spatial evolution of water discharges shows a different hydrological regime of the Rhône River, with relatively constant and high water stages and TSM concentrations when compared to coastal rivers, characterized by long periods of low water stages. TSM concentrations are positively correlated to water discharges (high water flows resuspended riverbed sediments) but show an inverse relationship with POC and PN relative contents (mostly due to dilution and by low availability of light in river waters during flood events). TSM in most of the coastal rivers have on average 2.5–3 times higher POC and PN mean contents than the Rhône River (8.5 and 1.5%, respectively, for coastal rivers compared to 3.6 and 0.5%, respectively, for the Rhône River). This discrepancy may be caused by the long drought periods in small coastal Mediterranean watersheds that enhance the eutrophication in studied coastal rivers. The δ13C ratios of organic matter also reflect this discrepancy between high and low water stages with values ranging from −33.2 to −24.5‰. The enriched 13C values (−26.3 ± 0.4‰ for the Rhône River and −26.9 ± 1.2‰ for coastal rivers), measured during high water stages, express mostly a mixture of terrestrial source (plant remains and soils) whereas depleted 13C values (∼ −30‰) associated with low water stages exhibit a source with predominant freshwater algae. The high δ15N mean values (>8‰) found in Têt, Ter and Tordera rivers may underline the importance of denitrification processes as a consequence of the eutrophication and anthropogenic impact.

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.

scholarly journals Copepods act as omnivores in a (sub)tropical reservoir: Implication for the top-down effect on phytoplankton

2018 ◽  
Vol 77 (2) ◽  
Author(s):  
Qiuqi Lin ◽  
Liang Peng ◽  
Yang Yang ◽  
Bo-Ping Han
Keyword(s):  
Organic Matter ◽  
Trophic Position ◽  
Zooplankton Community ◽  
Nitrogen Isotope ◽  
Terrestrial Organic Matter ◽  
Tropical Reservoir ◽  
Cascading Effect ◽  
Cladoceran Species ◽  
Grazing Effect ◽  
One Year

Tropical reservoirs in China receive a high input of organic matter from surrounding watersheds and this represents a significant resource for zooplankton consumers. Copepods are often the dominant zooplankton group in the tropical systems. Whether copepods tend to be omnivorous and their potential cascading effect on phytoplankton are subjects of debate. We used stable carbon and nitrogen isotope analyses to elucidate the allochthony and trophic positions of two copepod species (Phyllodiaptomus tunguidus and Mesocyclops thermocyclopoides) and one cladoceran species (Diaphanosoma orghidani) over a one-year period in a tropical oligo-mesotrophic reservoir in China. We assumed the filter-feeding D. orghidani was herbivorous and we used it as a baseline indicator of δ15N to estimate the trophic position of the two copepods. P. tunguidus and M. thermocyclopoides had an average trophic level that was 0.7 and 0.5 higher, respectively, than that of D. orghidani. M. thermocyclopoides showed seasonal differences in trophic position and an increase in trophic position with rising temperatures, whereas P. tunguidus remained omnivorous throughout the year. All three zooplankton species had a much higher degree of allochthony in the flood season than in the dry season, and their allochthony was positively related to the allochthony of the particulate organic matter input. The two copepods’ omnivorous behavior suggests their allochthony was primarily linked to microbial food web based on the input of terrestrial organic matter. The chlorophyll a to total phosphorus ratio was much higher when P. tunguidus dominated the zooplankton community than when D. orghidani dominated. The ratio was positively related to the ratio of omnivorous adult copepods to cladoceran biomass but not to the zooplankton:phytoplankton biomass ratio. Our results suggest that copepods tended to be omnivorous and relied heavily on allochthonous material in the study reservoir. The indirect cascading effect is likely to be stronger than the direct grazing effect, resulting in a positive effect of copepods on the phytoplankton.

scholarly journals Sources and export of particle-borne organic matter during a monsoon flood in a catchment of northern Laos

2015 ◽  
Vol 12 (4) ◽  
pp. 1073-1089 ◽  
Author(s):  
E. Gourdin ◽  
S. Huon ◽  
O. Evrard ◽  
O. Ribolzi ◽  
T. Bariac ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Particulate Organic Matter ◽  
Rainy Season ◽  
Overland Flow ◽  
Specific Yield ◽  
Main Stream ◽  
Δ13c And Δ15n ◽  
Suspended Organic Matter

Abstract. The yields of the tropical rivers of Southeast Asia supply large quantities of carbon to the ocean. The origin and dynamics of particulate organic matter were studied in the Houay Xon River catchment located in northern Laos during the first erosive flood of the rainy season in May 2012. This cultivated catchment is equipped with three successive gauging stations draining areas ranging between 0.2 and 11.6 km2 on the main stem of the permanent stream, and two additional stations draining 0.6 ha hillslopes. In addition, the sequential monitoring of rainwater, overland flow and suspended organic matter compositions was conducted at the 1 m2 plot scale during a storm. The composition of particulate organic matter (total organic carbon and total nitrogen concentrations, δ13C and δ15N) was determined for suspended sediment, soil surface (top 2 cm) and soil subsurface (gullies and riverbanks) samples collected in the catchment (n = 57, 65 and 11, respectively). Hydrograph separation of event water was achieved using water electric conductivity and δ18O measurements for rainfall, overland flow and river water base flow (n = 9, 30 and 57, respectively). The composition of particulate organic matter indicates that upstream suspended sediments mainly originated from cultivated soils labelled by their C3 vegetation cover (upland rice, fallow vegetation and teak plantations). In contrast, channel banks characterized by C4 vegetation (Napier grass) supplied significant quantities of sediment to the river during the flood rising stage at the upstream station as well as in downstream river sections. The highest runoff coefficient (11.7%), sediment specific yield (433 kg ha−1), total organic carbon specific yield (8.3 kg C ha−1) and overland flow contribution (78–100%) were found downstream of reforested areas planted with teaks. Swamps located along the main stream acted as sediment filters and controlled the composition of suspended organic matter. Total organic carbon specific yields were particularly high because they occurred during the first erosive storm of the rainy season, just after the period of slash-and-burn operations in the catchment.

Stable Carbon and Nitrogen Isotopes in the Tidal Flat Sediments of Northern Yellow Sea

2013 ◽  
Vol 316-317 ◽  
pp. 223-226
Author(s):  
Bao Zhan Liu ◽  
Yu Liu ◽  
Ying Li ◽  
Hai Xia Wang
Keyword(s):  
Organic Matter ◽  
Tidal Flat ◽  
Yellow Sea ◽  
Nitrogen Isotopes ◽  
Stable Carbon ◽  
Terrestrial Organic Matter ◽  
Δ13c And Δ15n ◽  
Carbon And Nitrogen Isotopes ◽  
Carbon And Nitrogen ◽  
Northern Yellow Sea

Stable carbon and nitrogen compositions (δ13C, δ15N) of sedimentary organic matter were determined in the tidal flat of northern Yellow sea. The results showed that stable carbon and nitrogen isotopes compositions of the sediment samples ranged from −24.669～−19.457‰ and 2.125～7.043‰, respectively. The highest value was in St.DLD, and the lowest was in St.Z. Similar δ13C values were observed in St.H (−21.996±0.651‰) and St.P (−22.021±0.187‰), and similar δ15N values were between St.DLJ (5.502±0.223‰) and St.P (5.310±0.294‰). The δ13C and δ15N values did not show any significant regularity. The δ13C and δ15N signatures showed some fluctuation, no obvious regularity. The major source of terrestrial organic matter was from the emissions of river and human pollutant.

scholarly journals Sources and export of particle-borne organic matter during a monsoon flood in a catchment of northern Laos

2014 ◽  
Vol 11 (6) ◽  
pp. 9341-9378
Author(s):  
E. Gourdin ◽  
S. Huon ◽  
O. Evrard ◽  
O. Ribolzi ◽  
T. Bariac ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Particulate Organic Matter ◽  
Rainy Season ◽  
Overland Flow ◽  
Specific Yield ◽  
Δ13c And Δ15n ◽  
Teak Plantations ◽  
The Impact

Abstract. Tropical rivers of Southeast Asia are characterized by high specific carbon yields and supplies to the ocean. The origin and dynamics of particulate organic matter were studied in the Houay Xon River catchment located in northern Laos during the first erosive flood of the rainy season in May 2012. The partly cultivated catchment is equipped with three successive gauging stations draining areas ranging between 0.2 and 11.6 km2 on the main stem of the permanent stream, and two additional stations draining 0.6 ha hillslopes. In addition, the sequential monitoring of rainwater, overland flow and suspended organic matter compositions was realized at 1 m2 plot scale during a single storm. The composition of particulate organic matter (total organic carbon, total nitrogen, δ13C and δ15N) was determined for suspended sediment, soil surface and subsurface samples collected in the catchment (n = 57, 65 and 11 respectively). Hydrograph separation of event water was conducted using water electric conductivity and δ18O data measured for rainfall, overland flow and river water base flow (n = 9, 30 and 57, respectively). The composition of particulate organic matter indicates that upstream suspended sediments were mainly derived from cultivated soils labelled by their C3 vegetation cover (upland rice, fallow vegetation and teak plantations) but that collapsed riverbanks, characterized by C4 vegetation occurrence (Napier grass), significantly contributed to sediment yields during water level rise and at the downstream station. The highest runoff coefficient (11.7%), sediment specific yield (433 kg ha−1), total organic carbon specific yield (8.3 kg C ha−1) and overland flow contribution (78–100%) were found for the reforested areas covered by teak plantations. Total organic carbon specific yields were up to 2.6-fold higher (at downstream station) than the annual ones calculated 10 years earlier, before the expansion of teak plantations in the catchment. They may be attributed both to the sampling period at the onset of the rainy season (following field clearing by slash and burn) and to the impact of land use change during the past decade.

Impacts of riverine terrestrial organic matter on the lower trophic levels of an Arctic shelf ecosystem

2021 ◽  
Author(s):  
Michael Bedington ◽  
Ricardo Torres ◽  
Luca Polimene ◽  
Phillip Wallhead ◽  
Bennett Juhls ◽  
...  
Keyword(s):  
Organic Matter ◽  
Future Climate ◽  
Trophic Levels ◽  
The Arctic ◽  
Nutrient Concentrations ◽  
Climate Scenarios ◽  
Arctic Ecosystems ◽  
Terrestrial Organic Matter ◽  
Biogeochemical Models ◽  
Near Shore

&lt;p&gt;The Arctic ocean receives 11% of the entire global river discharge via several great Arctic rivers that drain vast catchments underlain with carbon-rich permafrost. Arctic marginal shelf seas are therefore heavily influenced by terrestrial dissolved organic matter (tDOM) supply, influencing coastal biogeochemical processes and food-webs, as well as physio-chemical properties (e.g. stratification or nutrient concentrations).&lt;/p&gt;&lt;p&gt;Whilst carbon and associated macronutrients supplied by tDOM may enhance the nutrient and carbon substrates for lower trophic levels (phytoplankton/zooplankton), promoting increased local and regional productivity, it can also have opposing effects through a series of indirect processes (e.g. increased light absorption limiting light penetration through the water column). Understanding the relative importance and timing of these processes, and how they vary spatially, is necessary to identify how land-ocean interfaces currently operate.&lt;/p&gt;&lt;p&gt;Future climate scenarios indicate increased quantities of riverine tDOM delivered to the near-shore, with increased freshwater runoff and greater terrestrial permafrost thaw and erosion. This is likely to be exacerbated by the disappearance of seasonal sea ice cover and increased coastal erosion rates. We can therefore expect changes in planktonic phenology and productivity, with concomitant changes in bacterial and higher trophic level success. Understanding how these factors interact and may change under future climate scenarios is therefore critical to predict the future impact on shelf sea Arctic ecosystems and the ecosystem services they provide.&lt;/p&gt;&lt;p&gt;In the Changing Arctic Carbon cycle in the cOastal Ocean Near-shore (CACOON) project (UK-Germany collaboration) we are using coupled hydrodynamic-biogeochemical models in the extensive shallow shelf of the Laptev sea to explore the relationship between these factors. The ecosystem model ERSEM has been adapted to explicitly include a tDOM component. This coupled model system allows us to investigate both the role of present day tDOM in an Arctic coastal ecosystem and to project the potential impacts of increased tDOM input in future.&lt;/p&gt;

Trophic ecology and foraging areas of cetaceans sampled in the coastal waters of south-eastern Brazil assessed through skin δ13C and δ15N

2021 ◽  
pp. 1-10
Author(s):  
Victor Uber Paschoalini ◽  
Genyffer Cibele Troina ◽  
Laura Busin Campos ◽  
Marcos César de Oliveira Santos
Keyword(s):  
Habitat Use ◽  
Coastal Waters ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Trophic Levels ◽  
Eastern Coast ◽  
Cetacean Species ◽  
Δ13c And Δ15n ◽  
South Eastern ◽  
Eastern Brazil

Abstract We investigated the habitat use and feeding ecology of 10 cetacean species encountered along the south-eastern coast of Brazil (24–26°S) using carbon (δ13C) and nitrogen (δ15N) stable isotopes. Hierarchical cluster analysis distinguished two main groups based on their isotopic patterns. One group included migratory baleen whales (Megaptera novaeangliae and Eubalaena australis) with the lowest δ13C and δ15N values, reflecting baseline isotopic values of their Subantarctic feeding grounds and consumption of lower trophic level prey. Resident species and those occasionally occurring in Brazilian coastal waters highly differed from the migratory whales in their isotopic values. In this group, Tursiops truncatus had the highest δ13C and δ15N values, indicating coastal habits and relatively higher trophic position. Similar δ13C values were observed in Sotalia guianensis, Pontoporia blainvillei, Orcinus orca and Steno bredanensis. However, the former two species had lower δ15N values than the latter two, indicating different trophic positions. The relatively lower δ13C values observed in Stenella frontalis suggest greater influence of pelagic prey in their diet. Furthermore, the lower δ13C values observed in Delphinus delphis and Balaenoptera edeni were associated with upwelling events that occur along the region, affecting the isotopic values of their main prey. Juvenile M. novaeangliae had higher δ13C and δ15N than the adults, which may indicate feeding in areas with different isoscapes and consumption of pelagic schooling fish with relatively higher trophic levels than krill. This study provides preliminary information that are useful to understand the habitat use and coexistence of cetacean species occurring in south-eastern Brazil.

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.

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