scholarly journals Separate Feeding Between the Pelagic Stage of the Squat Lobster Munida gregaria and the Larger Sized Zooplankton Crustacean Groups in the Beagle Channel as Revealed by Stable Isotopes

2021 ◽  
Vol 8 ◽  
Author(s):  
Leonardo R. Castro ◽  
Humberto E. González ◽  
José Garcés-Vargas ◽  
Pamela Barrientos
Keyword(s):  
Organic Matter ◽  
Body Size ◽  
Vertical Distribution ◽  
Water Column ◽  
Food Sources ◽  
Isotopic Niche ◽  
Squat Lobster ◽  
Beagle Channel ◽  
Winter Conditions ◽  
Pelagic Stage

In southern Patagonia, the Beagle Channel shows very low production during winter but simultaneously sustains very dense aggregations of the pelagic stage of squat lobster (Munida gregaria), a benthic decapod whose pelagic juveniles have the largest body size within the chitinous pelagic community. To assess the coexistence of the mesozooplankton community and the pelagic M. gregaria stage under the harsh feeding winter conditions, we conducted a research cruise at two locations connected to the Beagle Channel, Yendegaia Bay (land terminating-glacier) and Pia Fjord (marine-terminating glacier). Our results showed that the zooplankton communities were similar in these two fjords, that a single pelagic group dominated in terms of biomass (pelagic Munida gregaria), and that differences in vertical distribution existed between most of the principal crustacean zooplankton and pelagic M. gregaria. All groups showed consumption of terrestrially derived organic matter, as revealed by their δ13C values. However, the isotopic composition, trophic positions (TP), and isotopic niche areas of the groups separated pelagic M. gregaria, presenting some of the lowest δ15N and the highest δ13C values, and the narrowest isotopic niche width. Pelagic M. gregaria was dominated by a single body size class along the 0–100 m water column, with no diel changes in vertical distribution, remained mostly in the upper layers (0–50 m), and benefited from the slightly higher phytoplankton concentrations at shallower depths as revealed by their higher δ13C values and low trophic position. In contrast, the other groups, including zoea M. gregaria stages, developed changes in distribution between day and night or remained deeper in the water column. These groups showed higher δ15N values, higher TP, and lower δ13C values, most of which probably fed on a nanoheterotrophs and terrestrial particulate organic matter mixture at deeper layers. Thus, the different vertical distributions, different trophic level food sources, and slightly different organic carbon sources apparently reduced any potential competence for food resources and form part of the feeding strategy that may facilitate the coexistence of the different large pelagic crustaceans under harsh feeding winter conditions in this high latitude austral region.

Methyl mercury in zooplankton—the role of size, habitat, and food quality

2002 ◽  
Vol 59 (10) ◽  
pp. 1606-1615 ◽  
Author(s):  
Martin Kainz ◽  
Marc Lucotte ◽  
Christopher C Parrish
Keyword(s):  
Organic Matter ◽  
Fatty Acid ◽  
Body Size ◽  
Methyl Mercury ◽  
Size Fraction ◽  
Food Sources ◽  
Calanoid Copepods ◽  
Bacterial Food

Pathways of methyl mercury (MeHg) accumulation in zooplankton include ingestion of organic matter (OM). We analyzed fatty acid (FA) biomarkers in zooplankton to (i) investigate the effect of allochthonous and autochthonous OM ingestion on MeHg concentrations ([MeHg]) in zooplankton and (ii) examine how algal and bacterial food sources affect MeHg bioaccumulation. We partitioned bulk zooplankton samples (i.e., >500, 202, 100, and 53 μm) from Lake Lusignan (Québec) and measured [MeHg] and [FA] in each fraction. [MeHg] increased with increasing body size and was significantly higher in pelagic than in littoral macrozooplankton (>500 μm). The amount of the ingested terrestrial FA biomarker 24:0 indicated that less than 1% of the total FA in zooplankton was derived from allochthonous sources. More than 60% of the ingested FA originated from algal biomarkers and <10% from bacterial biomarkers. Relative amounts of algal-derived essential FA and bacterial FA were not associated with [MeHg] in any size fraction. In pelagic zones, the amount of MeHg in zooplankton related positively to the number of large organisms such as Calanoid copepods and Daphnia. We propose that the accumulation of MeHg in lacustrine zooplankton depends on the zooplankton habitat rather than on the quality of ingested food.

scholarly journals Spatio–temporal variation in stable isotope signatures (δ13C and δ15N) of sponges on the Saba Bank

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5460 ◽  
Author(s):  
Fleur C. Van Duyl ◽  
Benjamin Mueller ◽  
Erik H. Meesters
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Environmental Changes ◽  
Food Sources ◽  
Sponge Species ◽  
Isotopic Niche ◽  
Δ13c And Δ15n ◽  
Spatio Temporal ◽  
Species Specific ◽  
Potential Food

Sponges are ubiquitous on coral reefs, mostly long lived and therefore adaptive to changing environmental conditions. They feed on organic matter withdrawn from the passing water and they may harbor microorganisms (endosymbionts), which contribute to their nutrition. Their diets and stable isotope (SI) fractionation determine the SI signature of the sponge holobiont. Little is known of spatio–temporal variations in SI signatures of δ13C and δ15N in tropical sponges and whether they reflect variations in the environment. We investigated the SI signatures of seven common sponge species with different functional traits and their potential food sources between 15 and 32 m depth along the S-SE and E-NE side of the Saba Bank, Eastern Caribbean, in October 2011 and October 2013. SI signatures differed significantly between most sponge species, both in mean values and in variation, indicating different food preferences and/or fractionation, inferring sponge species-specific isotopic niche spaces. In 2011, all sponge species at the S-SE side were enriched in d13C compared to the E-NE side. In 2013, SI signatures of sponges did not differ between the two sides and were overall lighter in δ13C and δ15N than in 2011. Observed spatio–temporal changes in SI in sponges could not be attributed to changes in the SI signatures of their potential food sources, which remained stable with different SI signatures of pelagic (particulate organic matter (POM): δ13C −24.9‰, δ15N +4.3‰) and benthic-derived food (macroalgae: δ13C −15.4‰, δ15N +0.8‰). Enriched δ13C signatures in sponges at the S-SE side in 2011 are proposed to be attributed to predominantly feeding on benthic-derived C. This interpretation was supported by significant differences in water mass constituents between sides in October 2011. Elevated NO3 and dissolved organic matter concentrations point toward a stronger reef signal in reef overlying water at the S-SE than N-NE side of the Bank in 2011. The depletions of δ13C and δ15N in sponges in October 2013 compared to October 2011 concurred with significantly elevated POM concentrations. The contemporaneous decrease in δ15N suggests that sponges obtain their N mostly from benthic-derived food with a lower δ15N than pelagic food. Average proportional feeding on available sources varied between sponge species and ranged from 20% to 50% for benthic and 50% to 80% for pelagic-derived food, assuming trophic enrichment factors of 0.5‰ ± sd 0.5 for δ13C and 3‰ ± sd 0.5 for δ15N for sponges. We suggest that observed variation of SI in sponges between sides and years were the result of shifts in the proportion of ingested benthic- and pelagic-derived organic matter driven by environmental changes. We show that sponge SI signatures reflect environmental variability in space and time on the Saba Bank and that SI of sponges irrespective of their species-specific traits move in a similar direction in response to these environmental changes.

Macrophyte-derived detritus in shallow coastal waters contributes to suspended particulate organic matter and increases growth rates of Mytilus edulis

2020 ◽  
Vol 644 ◽  
pp. 91-103
Author(s):  
D Bearham ◽  
MA Vanderklift ◽  
RA Downie ◽  
DP Thomson ◽  
LA Clementson
Keyword(s):  
Organic Matter ◽  
Mytilus Edulis ◽  
Particulate Organic Matter ◽  
Coastal Waters ◽  
Gill Tissue ◽  
Suspension Feeder ◽  
Food Sources ◽  
Suspension Feeders ◽  
Blue Mussels ◽  
Suspended Particulate

Benthic suspension feeders, such as bivalves, potentially have several different food sources, including plankton and resuspended detritus of benthic origin. We hypothesised that suspension feeders are likely to feed on detritus if it is present. This inference would be further strengthened if there was a correlation between δ13C of suspension feeder tissue and δ13C of particulate organic matter (POM). Since detritus is characterised by high particulate organic matter (POC):chl a ratios, we would also predict a positive correlation between POM δ13C and POC:chl a. We hypothesised that increasing depth and greater distance from shore would produce a greater nutritional reliance by experimentally transplanted blue mussels Mytilus edulis on plankton rather than macrophyte-derived detritus. After deployments of 3 mo duration in 2 different years at depths from 3 to 40 m, M. edulis sizes were positively correlated with POM concentrations. POC:chl a ratios and δ13C of POM and M. edulis gill tissue decreased with increasing depth (and greater distance from shore). δ13C of POM was correlated with δ13C of M. edulis. Our results suggest that detritus comprised a large proportion of POM at shallow depths (<15 m), that M. edulis ingested and assimilated carbon in proportion to its availability in POM, and that growth of M. edulis was higher where detritus was present and POM concentrations were higher.

scholarly journals The isotopic niche of Atlantic, biting marine mammals and its relationship to skull morphology and body size

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Massimiliano Drago ◽  
Marco Signaroli ◽  
Meica Valdivia ◽  
Enrique M. González ◽  
Asunción Borrell ◽  
...  
Keyword(s):  
Body Size ◽  
Atlantic Ocean ◽  
Fisheries Management ◽  
Marine Mammals ◽  
Trophic Position ◽  
Sympatric Species ◽  
Isotopic Niche ◽  
Apex Predators ◽  
Skull Morphology ◽  
Ecosystem Based Fisheries Management

AbstractUnderstanding the trophic niches of marine apex predators is necessary to understand interactions between species and to achieve sustainable, ecosystem-based fisheries management. Here, we review the stable carbon and nitrogen isotope ratios for biting marine mammals inhabiting the Atlantic Ocean to test the hypothesis that the relative position of each species within the isospace is rather invariant and that common and predictable patterns of resource partitioning exists because of constrains imposed by body size and skull morphology. Furthermore, we analyze in detail two species-rich communities to test the hypotheses that marine mammals are gape limited and that trophic position increases with gape size. The isotopic niches of species were highly consistent across regions and the topology of the community within the isospace was well conserved across the Atlantic Ocean. Furthermore, pinnipeds exhibited a much lower diversity of isotopic niches than odontocetes. Results also revealed body size as a poor predictor of the isotopic niche, a modest role of skull morphology in determining it, no evidence of gape limitation and little overlap in the isotopic niche of sympatric species. The overall evidence suggests limited trophic flexibility for most species and low ecological redundancy, which should be considered for ecosystem-based fisheries management.

UV radiation effects on the embryos of anchoveta (Engraulis ringens) and common sardine (Strangomera bentincki) off central Chile

2016 ◽  
Vol 67 (2) ◽  
pp. 195 ◽  
Author(s):  
P. Vásquez ◽  
A. Llanos-Rivera ◽  
L. R. Castro ◽  
C. Fernandez
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Radiation Effects ◽  
Hatching Success ◽  
Sublethal Effects ◽  
Ultraviolet B ◽  
Uvb Radiation ◽  
Central Chile ◽  
Fish Embryos ◽  
Engraulis Ringens

It has been proposed that current levels of ultraviolet B (UVB) radiation could cause lethal or sublethal effects on fish embryos located in the upper layers of the water column. Observed levels of UVB off central Chile (36°S, 73°W) indicate that planktonic fish embryos could be exposed to harmful UVB radiation. From July 2011 to January 2012 embryos from anchoveta (Engraulis ringens) and common sardine (Strangomera bentincki) were used to test experimentally whether the UVB levels in central Chile produce lethal or sublethal effects in epipelagic fish embryos. Simultaneously, whether the embryos might be exposed to harmful UVB levels in the field was investigated. Our experimental results show that UVB may cause a decrease in hatching success, changes in buoyancy and embryonic malformations. These results, along with the observed vertical distribution of embryos and UVB radiation levels in the field during late spring suggest that lethal and sublethal effects may be occurring in the embryos of both species.

Fine-root distribution of coniferous plantations in relation to site in southern Buenos Aires, Argentina

1992 ◽  
Vol 22 (11) ◽  
pp. 1575-1582 ◽  
Author(s):  
Adrián Ares ◽  
Norman Peinemann
Keyword(s):  
Organic Matter ◽  
Vertical Distribution ◽  
Root Distribution ◽  
Fine Roots ◽  
Buenos Aires ◽  
Fine Root ◽  
Organic Matter Content ◽  
Root Density ◽  
Site Quality ◽  
Coniferous Plantations

A study was conducted to determine the amounts and vertical distribution of fine roots <2 mm as a function of site quality in a temperate, hilly zone of Argentina. Fine roots were sampled in autumn from 0.2-ha plots established in 12 coniferous plantations of Pinushalepensis Mill., Pinusradiata D. Don, Cedrusdeodara (D. Don) G. Don, and Cupressussempervirens L.f. horizontalis, located in Sierra de la Ventana, southern Buenos Aires. Generally, root density was found to be higher under low-growth stands. The distance from a tree sometimes had an effect on root density, but no clear pattern within stands could be observed. Root density commonly decreased with depth, but slight irregularities in some profiles were observed. Site quality and soil type influenced root distribution. Belowground biomass up to a depth of 50 cm ranged from 1600 to 9800 kg•ha−1 in high-growth stands and from 5400 to 40 700 kg•ha−1 in low-growth stands. Soil organic matter content provided the best correlation with root density. A possible practical implication would be the use of indices related to vertical distribution of organic matter, among other variables, as complementary estimators of effective depth of rooting. The results strongly suggest that trees maintain a large fine-root system in poor sites at the expense of aboveground growth.

Pyrite geochemistry and fossil preservation in shales

1985 ◽  
Vol 311 (1148) ◽  
pp. 167-169 ◽  
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Sulphate Reduction ◽  
Pore Waters ◽  
Anoxic Waters ◽  
Iron Sulphides ◽  
Diagenetic Reaction ◽  
Fossil Preservation

As emphasized by Dr Seilacher in his introduction to this symposium, and illustrated in the contribution by Mr Martill, some of the most important examples of fossil Lagersätten occur in marine shales of Mesozoic age. Many of the factors that control the types and preservation of fossils are the same as those that affect the authigenic mineralogy and geochemistry of the shales, notably the degree of aeration or stagnation of the water column and the quantity and quality of the organic matter supplied to the sediment. Perhaps the most important diagenetic reaction in marine shales is sulphate reduction by bacteria that are obligate anaerobes. They can operate in anoxic waters or in ‘reducing microenvironments’ (such as concentrations of organic matter, or enclosed voids within shells) in sediments whose pore waters are kept generally oxic by the effects of burrowing organisms. Sulphate is reduced to sulphide and in the presence of reduced iron this can be precipitated as iron sulphides, normally found in ancient sediments in the form of pyrite. Pyrite is thus a key mineral in studying shale diagenesis, for its geochemistry as well as for its direct importance in preserving fossils by replacement of soft-parts (see, for example, Stürmer 1984), of aragonitic shells (see, for example, Fisher 1985) and by forming internal moulds of chambered shells (see, for example, Hudson & Palframan 1969; Hudson 1982).

Effects of Fe addition on sediment P dynamics in a eutrophic lake

2021 ◽  
Author(s):  
Melanie Münch ◽  
Rianne van Kaam ◽  
Karel As ◽  
Stefan Peiffer ◽  
Gerard ter Heerdt ◽  
...  
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Surface Water ◽  
Water Column ◽  
Sediment Cores ◽  
Surface Water Quality ◽  
Water Interface ◽  
Eutrophic Lakes ◽  
Fe Addition

&lt;p&gt;The decline of surface water quality due to excess phosphorus (P) input is a global problem of increasing urgency. Finding sustainable measures to restore the surface water quality of eutrophic lakes with respect to P, other than by decreasing P inputs, remains a challenge. The addition of iron (Fe) salts has been shown to be effective in removing dissolved phosphate from the water column of eutrophic lakes. However, the resulting changes in biogeochemical processes in sediments as well as the long-term effects of Fe additions on P dynamics in both sediments and the water column are not well understood.&lt;/p&gt;&lt;p&gt;In this study, we assess the impact of past Fe additions on the sediment P biogeochemistry of Lake Terra Nova, a well-mixed shallow peat lake in the Netherlands. The Fe-treatment in 2010 efficiently reduced P release from the sediments to the surface waters for 6 years. Since then, the internal sediment P source in the lake has been increasing again with a growing trend over the years.&lt;/p&gt;&lt;p&gt;In 2020, we sampled sediments at three locations in Terra Nova, of which one received two times more Fe during treatment than the other two. Sediment cores from all sites were sectioned under oxygen-free conditions. Both the porewaters and sediments were analysed for their chemical composition, with sequential extractions providing insight into the sediment forms of P and Fe. Additional sediment cores were incubated under oxic and anoxic conditions and the respective fluxes of P and Fe across the sediment water interface were measured.&lt;/p&gt;&lt;p&gt;The results suggest that Fe and P dynamics in the lake sediments are strongly coupled. We also find that the P dynamics are sensitive to the amount of Fe supplied, even though enhanced burial of P in the sediment was not detected. The results of the sequential extraction procedure for P, which distinguishes P associated with humic acids and Fe oxides, as well as reduced flux of Fe(II) across the sediment water interface in the anoxic incubations, suggest a major role of organic matter in the interaction of Fe and P in these sediments.&lt;/p&gt;&lt;p&gt;Further research will include investigations of the role of organic matter and sulphur in determining the success of Fe-treatment in sequestering P in lake sediments. Based on these data in combination with reactive transport modelling we aim to constrain conditions for successful lake restoration through Fe addition.&lt;/p&gt;

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