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13 pages, 2055 KiB

Open AccessArticle

Resource Use among Six Commercial Fish Species from the South-Eastern Gill Net Fisheries, Korea

by Min-Gu Kang, Sang-Heon Lee, Myung-Joon Kim, Seok-Nam Kwak, In-Seong Han and Joo-Myun Park

Water 2023, 15(6), 1146; https://doi.org/10.3390/w15061146 - 15 Mar 2023

Cited by 1 | Viewed by 2911

Dietary habits and inter-specific differences in resource use among six commercial fish species, Chelidonichthys spinosus, Cleisthenes pinetorum, Glyptocephalus stelleri, Hexagrammos otakii, Lophius litulon, and Sebastes schlegelii, collected from the southern coast of the East Sea, Korea, were [...] Read more.

Dietary habits and inter-specific differences in resource use among six commercial fish species, Chelidonichthys spinosus, Cleisthenes pinetorum, Glyptocephalus stelleri, Hexagrammos otakii, Lophius litulon, and Sebastes schlegelii, collected from the southern coast of the East Sea, Korea, were analyzed using stomach content and stable isotope analyses. Teleosts were the main prey items for C. pinetorum and L. litulon, while both crabs and teleosts contributed to the diets of C. spinosus and S. schlegelii. Glyptocephalus stelleri mainly consumed polycheates and carid shrimps, and H. otakii mostly ingested crabs. The composition of prey items was significantly different in the diets of the six fish species. Further, carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotope values were significantly different among the six species, indicating different trophic positions. L. litulon, C. pinetorum, and S. schlegelii had narrow niches, whereas C. spinosus, G. stelleri, and H. otakii had relatively wider niches. This study demonstrated differences in patterns of food resource use among the six fish species that were categorized into two patterns of resource use according to their main prey items: diet diversity, trophic niche width, and trophic position. These results could contribute to the understanding of trophic relationships among fish species inhabiting the East Sea, Korea. Full article

(This article belongs to the Special Issue Application of Stable Isotopes in Marine Ecosystems)

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13 pages, 1563 KiB

Open AccessArticle

Trophic Assessment of an Artificial Kelp Eisenia bicyclis Bed Off the Eastern Coast of Korea Based on Stable Isotope Analyses

by Tae Hee Park, Jae-Bin Jang, Chan-Kil Chun, Youngkweon Lee, Kyu-Sam Han, Su-Jeong Yang and Hyun Je Park

Water 2023, 15(6), 1099; https://doi.org/10.3390/w15061099 - 13 Mar 2023

Viewed by 2042

Abstract

Effective trophic assessment of restoration success after the creation of an artificial habitat is essential for ecological management. In this study, to evaluate the ecological trophic function of restored kelp beds of artificial macroalgal reefs (AMRs) attached with the kelp species Eisenia bicyclis [...] Read more.

Effective trophic assessment of restoration success after the creation of an artificial habitat is essential for ecological management. In this study, to evaluate the ecological trophic function of restored kelp beds of artificial macroalgal reefs (AMRs) attached with the kelp species Eisenia bicyclis, we compared carbon and nitrogen stable isotope ratios of organic matter sources and macrobenthic consumers and isotopic indices of functional feeding groups between artificial and reference (natural bed and barren ground, respectively) habitats. There were no significant differences in isotopic values of consumer feeding groups (except for carnivores) and their potential food sources between the artificial and natural sites, suggesting that resource diversity and resource use by consumers was similar across all sites. The isotopic data also exhibited similar or relatively higher trophic niches of feeding groups at the artificial site compared to those at the natural site, indicating that the artificial kelp bed can play important roles in similar ecological functions and services as a natural counterpart. In addition, the present study revealed that the isotopic ranges and niche indices of feeding groups were significantly wider at the artificial and natural kelp beds compared to those at the barren ground, suggesting the trophic importance of macroalgal-derived organic matter to consumer nutrition in coastal ecosystems. Overall, our results support the conclusion that the creation of an Eisenia bicyclis kelp bed by the AMRs may lead to the restoration success of the macroalgae habitat through the recovery of the ecological function of a natural food web structure. Full article

(This article belongs to the Special Issue Application of Stable Isotopes in Marine Ecosystems)

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14 pages, 3724 KiB

Open AccessArticle

Trophic Positions of Sympatric Copepods across the Subpolar Front of the East Sea during Spring: A Stable Isotope Approach

by Dong-Hoon Im and Hae-Lip Suh

Water 2023, 15(3), 416; https://doi.org/10.3390/w15030416 - 19 Jan 2023

Cited by 1 | Viewed by 2081

Abstract

We investigated the trophic relationship between particulate organic matter (POM) and sympatric copepods within the epipelagic zone (~200 m depth) in the East Sea during spring based on stable isotope analysis (SIA). The SIA indicated that interspecific differences in the prey size and [...] Read more.

We investigated the trophic relationship between particulate organic matter (POM) and sympatric copepods within the epipelagic zone (~200 m depth) in the East Sea during spring based on stable isotope analysis (SIA). The SIA indicated that interspecific differences in the prey size and vertical segregation of feeding migration range among copepods may promote niche partitioning among sympatric copepods in each region of the subpolar front (SPF). Additionally, our results showed remarkable differences in the copepod community structure and resource utilization across the SPF. The south region of the East Sea showed higher species richness of copepods than the north region, while copepods that fed mainly on POM in the surface and subsurface chlorophyll maximum layers showed smaller body sizes in the south region. These results revealed that the food chain between primary producers and higher trophic levels was longer in the south region than in the north region. Additionally, δ¹³C and δ¹⁵N values of copepods increased gradually with the body size increase whereas δ¹⁵N values in the north region showed the reverse trend. Latter results could be attributed to the consumption of deep-layer POM in small copepods. Therefore, we suggest that northward shifts in the distribution of copepods under global warming may decrease energy efficiency in the pelagic ecosystem of the East Sea. Full article

(This article belongs to the Special Issue Application of Stable Isotopes in Marine Ecosystems)

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20 pages, 4578 KiB

Open AccessArticle

Tidal Flushing Rather Than Non-Point Source Nitrogen Pollution Drives Nutrient Dynamics in A Putatively Eutrophic Estuary

by Johannes R. Krause, Michelle E. Gannon, Autumn J. Oczkowski, Morgan J. Schwartz, Lena K. Champlin, David Steinmann, Martha Maxwell-Doyle, Emily Pirl, Victoria Allen and Elizabeth Burke Watson

Water 2023, 15(1), 15; https://doi.org/10.3390/w15010015 - 21 Dec 2022

Cited by 3 | Viewed by 2832

Abstract

The effects of nonpoint source nutrients on estuaries can be difficult to pinpoint, with researchers often using indicator species, monitoring, and models to detect influence and change. Here, we made stable isotope measurements of nitrogen and carbon in sediment, water column particulates, primary [...] Read more.

The effects of nonpoint source nutrients on estuaries can be difficult to pinpoint, with researchers often using indicator species, monitoring, and models to detect influence and change. Here, we made stable isotope measurements of nitrogen and carbon in sediment, water column particulates, primary producers, and consumers at 35 stations in the reportedly eutrophic Barnegat Bay (New Jersey) to assess N sources and processing pathways. Combined with water quality and hydrological data, our C and N isoscapes revealed four distinct geographic zones with diverging isotopic baselines, indicating variable nutrient sources and processing pathways. Overall, the carbon stable isotopes (δ¹³C) reflected the terrestrial-marine gradient with the most depleted values in the urban and poorly flushed north of the estuary to the most enriched values in the salt marsh-dominated south. In contrast, the nitrogen stable isotope values (δ¹⁵N) were most enriched near the oceanic inlets and were consistent with offshore δ¹⁵N values in particulate organic matter. Several biogeochemical processes likely alter δ¹⁵N, but the relatively lower δ¹⁵N values associated with the most urbanized area indicate that anthropogenic runoff is not a dominant N source to this area. Our findings stand in contrast to previous studies of similar estuaries, as δ¹⁵N signatures of biota in this system are inversely correlated to population density and nutrient concentrations. Further, our analyses of archival plant (Spartina sp., Phragmites australis) and shell (Geukensia demissa, Ilyanassa obsoleta) samples collected between 1880 and 2020 indicated that δ¹⁵N values have decreased over time, particularly in the consumers. Overall, we find that water quality issues appear to be most acute in the poorly flushed parts of Barnegat Bay and emphasize the important role that oceanic exchange plays in water quality and associated estuarine food webs in the lagoon. Full article

(This article belongs to the Special Issue Application of Stable Isotopes in Marine Ecosystems)

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21 pages, 3373 KiB

Open AccessFeature PaperArticle

Dietary Changes in the Ark Clam (Anadara kagoshimensis) Is Associated with Phytoplankton Community Patterns in a Temperate Coastal Embayment

by Hee Yoon Kang, Changseong Kim, Dongyoung Kim, Kee-Young Kwon, Won Chan Lee and Chang-Keun Kang

Water 2022, 14(21), 3497; https://doi.org/10.3390/w14213497 - 1 Nov 2022

Viewed by 2095

Abstract

The monthly phytoplankton communities and dietary items of the filter-feeding ark clam (Anadara kagoshimensis) in cultivation were examined in a shallow temperate coastal embayment of Yeoja Bay in Korea, to identify dietary changes in clams associated with phytoplankton community patterns. A [...] Read more.

The monthly phytoplankton communities and dietary items of the filter-feeding ark clam (Anadara kagoshimensis) in cultivation were examined in a shallow temperate coastal embayment of Yeoja Bay in Korea, to identify dietary changes in clams associated with phytoplankton community patterns. A self-organizing map (SOM) algorithm was applied to shape the community structures of phytoplankton. Clam δ¹³C and δ¹⁵N values were determined monthly and compared with those of phytoplankton, microphytobenthos, suspended particulate organic matter (SPOM), sedimentary organic matter (sedimentary OM), and Phragmites australis. Our SOM clustered monthly phytoplankton communities, revealing a seasonal shift in the dominance of large-sized diatoms (sporadically together with dinoflagellates), which were detected almost year-round, to small-sized taxa (chlorophytes, prasinophytes, and prymnesiophytes), which were observed in May–June. The δ¹³C and δ¹⁵N measurements revealed that pelagic and benthic diatoms serve as the main contributors to the clam diets. A reduction in their dietary contribution accompanied a considerable increment in the contribution of Phragmites detritus in association with the dominance of small-sized phytoplankton during the late spring. Our results suggest that the dominance of small-sized phytoplankton during the critical spring period of the clam life cycle may decrease the availability of preferred items (i.e., size-related food quality) and lead to dietary changes in the clams in relation to climate forcing in this warming sea. Full article

(This article belongs to the Special Issue Application of Stable Isotopes in Marine Ecosystems)

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14 pages, 1525 KiB

Open AccessArticle

Feeding Ecology of Common Squid Todarodes pacificus in the South Sea of Korea Determined through Stable Isotope and Stomach Content Analyses

by Donghoon Shin, Tae Hee Park, Chung-Il Lee, Jun Hyung Jo, Chang Geun Choi, Sukyung Kang and Hyun Je Park

Water 2022, 14(19), 3159; https://doi.org/10.3390/w14193159 - 7 Oct 2022

Cited by 3 | Viewed by 2411

Abstract

The common squid Todarodes pacificus is a dominant species within epipelagic communities and an important commercial species in the South and East seas of Korea and in the East China Sea. In this study, to examine the dietary composition, trophic position, and ontogenetic [...] Read more.

The common squid Todarodes pacificus is a dominant species within epipelagic communities and an important commercial species in the South and East seas of Korea and in the East China Sea. In this study, to examine the dietary composition, trophic position, and ontogenetic dietary shifts of the common squid, we analyzed stomach contents and stable isotope values (δ¹³C and δ¹⁵N) in muscle tissue across different body sizes (mantle length, ML) and seasons (winter, spring, and summer 2021) in the South Sea of Korea. Regardless of the season, the diet of the common squid predominantly comprised Pisces (37.9–94.0%) and Cephalopoda (6.0–61.0%). However, in the smallest individuals (ML < 10 cm), the stomach contents in August primarily comprised Crustacea (95.5%), thereby indicating a seasonal difference in dietary composition and ontogenetic dietary shifts only during summer. Similarly, our isotope results revealed seasonal isotopic variation among sampling periods and significant positive correlations between ML and both δ¹³C and δ¹⁵N values during the summer. These results reveal a seasonal variability in major diet components among the common squid of different size classes and that their feeding strategies are probably adjusted in response to the temporal availability of prey. Collectively, the findings of this study enhance our understanding of the feeding ecology of T. pacificus and thereby provide valuable information that will contribute to the ecological fishery management of this commercially important species. Full article

(This article belongs to the Special Issue Application of Stable Isotopes in Marine Ecosystems)

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13 pages, 1558 KiB

Open AccessArticle

Recovery of Macrobenthic Food Web on Rocky Shores Following the Hebei Spirit Oil Spill as Revealed by C and N Stable Isotopes

by Hyun Je Park, Changseong Kim and Chang-Keun Kang

Water 2022, 14(15), 2335; https://doi.org/10.3390/w14152335 - 28 Jul 2022

Cited by 3 | Viewed by 1856

Abstract

The impact of large-scale oil spills on organisms can lead to modifications of the food web structure. To assess the effects of the Hebei Spirit oil-spill accident on the trophic structure of the macrobenthic community on intertidal rocky shores along Taean Peninsula on [...] Read more.

The impact of large-scale oil spills on organisms can lead to modifications of the food web structure. To assess the effects of the Hebei Spirit oil-spill accident on the trophic structure of the macrobenthic community on intertidal rocky shores along Taean Peninsula on the western coast of Republic of Korea 4 years after the Hebei Spirit oil spill, we analyzed carbon and nitrogen stable isotope ratios of macrobenthic consumers and their potential food sources in two heavily oil-impacted and one non-impacted sites. The results show no significant differences in isotopic ratios of feeding groups and their potential food sources between the polluted and reference sites, suggesting similar trophic structures given similar resource use by consumers. Similar isotopic niches and substantial overlap areas of feeding groups between the affected and reference sites suggest that the oil-impacted sites have re-achieved the trophic functions of the natural ecosystem. This study provides valuable information on the ecological processes of trophic recovery in coastal ecosystems impacted by oil spills. Full article

(This article belongs to the Special Issue Application of Stable Isotopes in Marine Ecosystems)

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17 pages, 1284 KiB

Open AccessFeature PaperArticle

Characterization of Trophic Structure of Fish Assemblages in the East and South Seas of Korea Based on C and N Stable Isotope Ratios

by Donghoon Shin, Tae Hee Park, Chung-Il Lee, Kangseok Hwang, Doo Nam Kim, Seung-Jong Lee, Sukyung Kang and Hyun Je Park

Water 2022, 14(1), 58; https://doi.org/10.3390/w14010058 - 28 Dec 2021

Cited by 3 | Viewed by 2212

Abstract

The aim of this study was to assess seasonal variation in the food-web structure of fish assemblages in the East (two sites) and the South (one site) Seas of Korea, and to compare the isotopic niche areas between the regions. To do this, [...] Read more.

The aim of this study was to assess seasonal variation in the food-web structure of fish assemblages in the East (two sites) and the South (one site) Seas of Korea, and to compare the isotopic niche areas between the regions. To do this, we analyzed the community structures and the δ¹³C and δ¹⁵N values for fish assemblages, and their potential food sources collected during May and October 2020. There were spatial differences in the diversity and dominant species of fish assemblages between the two seas. The fish assemblages in the South Sea had relatively wide ranges of δ¹³C and δ¹⁵N (−22.4‰ to −15.3‰ and 7.4‰ to 13.8‰, respectively) compared to those (−22.1‰ to −18.0‰ and 9.8‰ to 13.6‰, respectively) in the East Sea. The δ¹³C and δ¹⁵N values of suspended particulate organic matter, zooplankton, and fish assemblages differed significantly among sites and between seasons (PERMANOVA, p < 0.05, in all cases). Moreover, isotopic niche indices were relatively higher in the South Sea compared to those in the East Sea. Such differences in food-web characteristics among sites are likely due to the specific environmental effects (especially, major currents) on the differences in the species compositions and, therefore, their trophic relationships. Overall, these results allow for a deeper understanding of the changing trophic diversity and community structure of fish assemblages resulting from climate variability. Full article

(This article belongs to the Special Issue Application of Stable Isotopes in Marine Ecosystems)

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