Year-to-Year and Inter-Decadal Fluctuations in Abundance of Pelagic Fish Populations in Relation to Climate-Induced Oceanic Conditions

Gong, Yeong*,Young-Sang Suh,In-Seong Han,Ki-Tack Seong 한국생태학회 2008 Journal of Ecology and Environment Vol.31 No.1

Ocean climate variables (1900~2005), time series of catches (1910~2005) and body size data were used to assess the year-to-year and decadal scale fluctuations in abundance of the fish populations (Japanese sardine, anchovy, jack mackerel, chub mackerel, Pacific saury and common squid) that have spawning grounds in the East China Sea and its adjacent regions. A negative correlation between the abundance of pelagic fishes (e.g. jack mackerel) in the Tsushima Warm Current (TWC) region and the Kuroshio-Oyashio Current (KOC) region was attributed to the climatic modulation of larval transport and recruitment, which depends on the winter monsoon-induced drift, current systems, and spawning season and site. The changes in abundance and alternation of dominant fish populations in the two regions in the 1930s, 1970s, and late 1980s mirrored changes in the climate indices (ALPI, AOI and MOI). Oscillations in the decadal climate shifts between the two regions led to zonal differences in larval transport and recruitment, and hence differences in the abundance of the pelagic fish populations. During deep Aleutian Lows, as in the 1980s, larval transport from the East China Sea to the KOC region increases in association with the strong winter Asian monsoon, cool regime and increased volume transport of the Kuroshio Current systems, whereas during a weak Aleutian Low (as in the 1990s), larval transport to the TWC region increased in association with a weak winter Asian monsoon, a warm regime, and increased volume transport of the Tsushima current system. We postulate that the increased chub mackerel abundance in the TWC region and the decreased abundance in the KOC region in the 1990s are partly attributed to changes in recruitment and availability to the fishing fleets under the warm regime in the spawning and nursery grounds in the East China Sea in association with the quasi-steady state of mild winter monsoon in the 1990s. The fluctuations in chub mackerel and jack mackerel abundance are under the environment-dependant growth form, although the tropicalization was identified in the TWC region. The density-dependant growth form was found in Japanese sardine populations, but no tropicalization by fishing was identified in the long (10~15 year) periods of abundance despite their short (3~4 year) generation time, suggesting that the environment-dependant growth form drove the changes in abundance. Year-to-year and decadal scale variations in abundance and population structure of the Pacific saury responded to climate regime shifts (1976/1977, 1988/1989), suggesting that the fish is a key bio-indicators for changes in the ecosystem. Ocean climate variables (1900~2005), time series of catches (1910~2005) and body size data were used to assess the year-to-year and decadal scale fluctuations in abundance of the fish populations (Japanese sardine, anchovy, jack mackerel, chub mackerel, Pacific saury and common squid) that have spawning grounds in the East China Sea and its adjacent regions. A negative correlation between the abundance of pelagic fishes (e.g. jack mackerel) in the Tsushima Warm Current (TWC) region and the Kuroshio-Oyashio Current (KOC) region was attributed to the climatic modulation of larval transport and recruitment, which depends on the winter monsoon-induced drift, current systems, and spawning season and site. The changes in abundance and alternation of dominant fish populations in the two regions in the 1930s, 1970s, and late 1980s mirrored changes in the climate indices (ALPI, AOI and MOI). Oscillations in the decadal climate shifts between the two regions led to zonal differences in larval transport and recruitment, and hence differences in the abundance of the pelagic fish populations. During deep Aleutian Lows, as in the 1980s, larval transport from the East China Sea to the KOC region increases in association with the strong winter Asian monsoon, cool regime and increased volume transport of the Kuroshio Current systems, whereas during a weak Aleutian Low (as in the 1990s), larval transport to the TWC region increased in association with a weak winter Asian monsoon, a warm regime, and increased volume transport of the Tsushima current system. We postulate that the increased chub mackerel abundance in the TWC region and the decreased abundance in the KOC region in the 1990s are partly attributed to changes in recruitment and availability to the fishing fleets under the warm regime in the spawning and nursery grounds in the East China Sea in association with the quasi-steady state of mild winter monsoon in the 1990s. The fluctuations in chub mackerel and jack mackerel abundance are under the environment-dependant growth form, although the tropicalization was identified in the TWC region. The density-dependant growth form was found in Japanese sardine populations, but no tropicalization by fishing was identified in the long (10~15 year) periods of abundance despite their short (3~4 year) generation time, suggesting that the environment-dependant growth form drove the changes in abundance. Year-to-year and decadal scale variations in abundance and population structure of the Pacific saury responded to climate regime shifts (1976/1977, 1988/1989), suggesting that the fish is a key bio-indicators for changes in the ecosystem.

Variation in Fish Abundance in Different Habitats of a Tropical Lagoon with an Attempt to Model the Effects of Physico-Chemical Parameters on Their Abundance

Sulakkana Wanshapaly Rathnayake,Sithara Rasanjali Sirimanna,Chamari Thathsaramala Dissanayake 한국해양과학기술원 2022 Ocean science journal Vol.57 No.1

This study assesses the abundance of fish in different habitats of Negombo Lagoon, a human-influenced, highly productive tropical lagoon in Sri Lanka, and the effects of physico-chemical parameters on their abundance. Six different habitats, i.e., three mangrove habitats, seagrass bed associated habitat, brushpile, and mud and sand flat were selected as sampling sites representing three major areas, Kadolkele, Dungalpitiya, and Kepungoda. Fish were sampled using a drag net with a stretch mesh size of 50 mm and salinity, Surface Water Temperature, Dissolved Oxygen, pH, Nitrate–N and Orthophosphate were measured in each habitat from January to December 2018 by making monthly field visit. A total of 45 fish species belonging to 30 families were identified. The highest species abundance was reported in seagrass associated habitat, while the lowest was in Kadolkele mangrove habitat (p < 0.05; ANOVA) due to its low level of DO (1.92 mg dm−3) and high Orthophosphate (1.02 mg dm−3) content. Different life stages of fish shared different habitats and small juveniles were abundant in association with seagrass bed (67.09%) while mature ones were dominant (42.12%) in brushpile area. This study proves that the abundance of fish varies with different physico-chemical parameters and, according to the generalized additive model, the highest abundance of fish is in association with > DO of 4 mg dm−3, low level of Orthophosphate (0.5–0.75 mg dm−3), 0.5–1.5 mg dm−3 of Nitrate–N, and 20–30 ppt salinity. The findings of this study are important to understand the spatial and seasonal patterns of fish abundance in a tropical lagoon and how physico-chemical parameters affect their abundance.

Habitat selectivity of fresh water fishes of two second-order tropical streams in Tigray, Northern Ethiopia

Tesfay, Solomon,Teferi, Mekonen,Tsegazeabe, Haileselasie Hadush The Ecological Society of Korea 2019 Journal of Ecology and Environment Vol.43 No.1

Background: Habitat selectivity and ecology of freshwater fishes were studied in two selected streams and their junction point which consist a total of 39 microhabitats. The aims of this study were to describe the habitat preference and its availability to fish assemblage, as well as ecology, habitat use, and habitat characteristics. Methods: We collected fish with backpack electrofishing three times during August 2013, December 2013, and March 2014. Using a variation partitioning approach of R software, we studied the relationship of fish abundances with stream type, habitat type, and abundance of key macroinvertebrate taxa. Results: A total of 6554 fishes representing four species belonging to the family Cyprinidae were caught. A higher total fish abundance was recorded from Gereb Tsedo (4870; 74.3%) than from Elala stream (1684; 25.7%). Taking both streams together, the overall total relative fish abundance was significantly higher in pools (53%) than in runs (35%) and in riffles (12%) at P < 0.05. Species-wise comparisons showed that 71%, 15%, 13%, and 1% of the pool fish community were occupied by Garra blanfordii, Garra ignestii, Garra dembecha, and Garra aethiopica, respectively. Stream type, habitat type, and key macroinvertebrate taxa each explained a significant proportion of the variation in fish abundance. Based on the variation partitioning approach, fish abundance was higher in Gereb Tsedo stream (P < 0.01). Moreover, fish abundance increased with pool habitat type (P < 0.01) and with availability of key macroinvertebrate taxa (P < 0.01). Conclusion: Fish abundance differed between stream types, among habitats and among key macroinvertebrate taxa availability. Among the factors, habitat type was the most important driving factor behind variation among fish abundances, and pool supports the highest fish abundance.

Resource Assessment of Polymetallic Nodules Using Acoustic Backscatter Intensity Data from the Korean Exploration Area, Northeastern Equatorial Pacific

유찬민,주종민,이상훈,고영탁,지상범,김형직,서인아,형기성 한국해양과학기술원 2018 Ocean science journal Vol.53 No.2

A high level of confidence in resource data is a key prerequisite for conducting a reliable economic feasibility study in deep water seafloor mining. However, the acquisition of accurate resource data is difficult when employing traditional point-sampling methods to assess the resource potential of polymetallic nodules, given the vast size of the survey area and high spatial variability in nodule distribution. In this study, we analyzed high-resolution acoustic backscatter intensity images to estimate nodule abundance and increase confidence levels in nodule abundance data. We operated a 120 kHz deep-towed sidescan sonar (DSL-120) system (1×1 m resolution) across a 75 km2 representative area in the Korean Exploration Area for polymetallic nodules in the Northeastern Equatorial Pacific. A deep-towed camera system was also run along two tracks in the same area to estimate the abundance of polymetallic nodules on the seafloor. Backscatter data were classified into four facies based on intensity. The facies with the weakest and strongest backscatter intensities occurred in areas of high slope gradient and basement outcrops, respectively. The backscatter intensities of the two other facies correlated well with the nodule abundances estimated from still-camera images. A linear fit between backscatter intensity and mean nodule abundance for 10 zones in the study area yielded an excellent correlation (r2 = 0.97). This allowed us to compile a map of polymetallic nodule abundance that shows greater resolution than a map derived from the extrapolation of point-sampling data. Our preliminary analyses indicate that it is possible to greatly increase the confidence level of nodule resource data if the relationship between backscatter intensity and nodule abundance is reliably established. This approach has another key advantage over point sampling and image analyses in that detailed maps of mining obstacles along the seafloor are produced when acquiring data on the abundance of polymetallic nodules. The key limitation of this work is a poor correlation between nodule coverage, as observed from photographs, and nodule abundance. Significant additional ground truth sampling using well located box cores should be completed to determine whether or not there is a real correlation between the backscatter and abundance.

Resource Assessment of Polymetallic Nodules Using Acoustic Backscatter Intensity Data from the Korean Exploration Area, Northeastern Equatorial Pacific

Yoo, Chan Min,Joo, Jongmin,Lee, Sang Hoon,Ko, Youngtak,Chi, Sang-Bum,Kim, Hyung Jeek,Seo, Inah,Hyeong, Kiseong Korean Ocean Research & Development Institute and 2018 OCEAN SCIENCE JOURNAL Vol.53 No.2

A high level of confidence in resource data is a key prerequisite for conducting a reliable economic feasibility study in deep water seafloor mining. However, the acquisition of accurate resource data is difficult when employing traditional point-sampling methods to assess the resource potential of polymetallic nodules, given the vast size of the survey area and high spatial variability in nodule distribution. In this study, we analyzed high-resolution acoustic backscatter intensity images to estimate nodule abundance and increase confidence levels in nodule abundance data. We operated a 120 kHz deep-towed sidescan sonar (DSL-120) system (<TEX>$1{\times}1m$</TEX> resolution) across a <TEX>$75km^2$</TEX> representative area in the Korean Exploration Area for polymetallic nodules in the Northeastern Equatorial Pacific. A deep-towed camera system was also run along two tracks in the same area to estimate the abundance of polymetallic nodules on the seafloor. Backscatter data were classified into four facies based on intensity. The facies with the weakest and strongest backscatter intensities occurred in areas of high slope gradient and basement outcrops, respectively. The backscatter intensities of the two other facies correlated well with the nodule abundances estimated from still-camera images. A linear fit between backscatter intensity and mean nodule abundance for 10 zones in the study area yielded an excellent correlation (<TEX>$r^2=0.97$</TEX>). This allowed us to compile a map of polymetallic nodule abundance that shows greater resolution than a map derived from the extrapolation of point-sampling data. Our preliminary analyses indicate that it is possible to greatly increase the confidence level of nodule resource data if the relationship between backscatter intensity and nodule abundance is reliably established. This approach has another key advantage over point sampling and image analyses in that detailed maps of mining obstacles along the seafloor are produced when acquiring data on the abundance of polymetallic nodules. The key limitation of this work is a poor correlation between nodule coverage, as observed from photographs, and nodule abundance. Significant additional ground truth sampling using well located box cores should be completed to determine whether or not there is a real correlation between the backscatter and abundance.

Habitat selectivity of fresh water fishes of two second-order tropical streams in Tigray, Northern Ethiopia

Solomon Tesfay,Mekonen Teferi,Haileselasie Hadush Tsegazeabe 한국생태학회 2019 Journal of Ecology and Environment Vol.43 No.1

Background: Habitat selectivity and ecology of freshwater fishes were studied in two selected streams and their junction point which consist a total of 39 microhabitats. The aims of this study were to describe the habitat preference and its availability to fish assemblage, as well as ecology, habitat use, and habitat characteristics. Methods: We collected fish with backpack electrofishing three times during August 2013, December 2013, and March 2014. Using a variation partitioning approach of R software, we studied the relationship of fish abundances with stream type, habitat type, and abundance of key macroinvertebrate taxa. Results: A total of 6554 fishes representing four species belonging to the family Cyprinidae were caught. A higher total fish abundance was recorded from Gereb Tsedo (4870; 74.3%) than from Elala stream (1684; 25.7%). Taking both streams together, the overall total relative fish abundance was significantly higher in pools (53%) than in runs (35%) and in riffles (12%) at P < 0.05. Species-wise comparisons showed that 71%, 15%, 13%, and 1% of the pool fish community were occupied by Garra blanfordii, Garra ignestii, Garra dembecha, and Garra aethiopica, respectively. Stream type, habitat type, and key macroinvertebrate taxa each explained a significant proportion of the variation in fish abundance. Based on the variation partitioning approach, fish abundance was higher in Gereb Tsedo stream (P < 0.01). Moreover, fish abundance increased with pool habitat type (P < 0.01) and with availability of key macroinvertebrate taxa (P < 0.01). Conclusion: Fish abundance differed between stream types, among habitats and among key macroinvertebrate taxa availability. Among the factors, habitat type was the most important driving factor behind variation among fish abundances, and pool supports the highest fish abundance.

Prediction of abundance of beetles according to climate warming in South Korea

권태성,이철민,김성수 국립중앙과학관 2015 Journal of Asia-Pacific Biodiversity Vol.8 No.1

To identify the change in distribution of insects in climate warming, changes in abundance of beetles were predicted using data from 366 survey sites (forests) in South Korea. Abundance along temperature gradients showed patterns (linear or hump-shaped) of normal distribution for 18 candidate species. Mean abundance in temperature zones of these species was used to predict the change in abundance. Temperature change was based on climate scenario Representative Concentration Pathways (RCP) 4.5 and 8.5 and abundance of the two periods from 2011 to 2015 and 2056 to 2065 were predicted. Of the 18 species analyzed, six were predicted to increase in abundance and 12 were predicted to decrease. Using a high relationship between abundance change and temperature of collected sites, a qualitative prediction was conducted on non-candidate species with ? 1% occurrence. This prediction also shows that more beetle species in South Korea will decrease rather than increase as climate warms.

Prediction of abundance of ants according to climate change scenarios RCP 4.5 and 8.5 in South Korea

권태성,이철민 국립중앙과학관 2015 Journal of Asia-Pacific Biodiversity Vol.8 No.1

In order to identify change of ant distribution expected due to climate change in South Korea, data on ants collected from 344 forest sites were used to predict change of abundance of ant species. In distribution of abundance along temperature gradient, 16 species displayed the patterns expected from normal distribution. For these species, abundance in temperature zones was used to link with temperature changes and predict the abundance. Temperature changes were based on Representative Concentration Pathways (RCP) 4.5 and 8.5, and the national average and distribution of abundance during the two periods from 2011 to 2015 and from 2056 to 2065 were predicted. The rate of change of ant abundance and the average temperature of the collection sites showed a clearly positive relationship. Based on these results, qualitative prediction (increase or decrease) was conducted for species with ≥ 1% occurrence. The results showed that eight species would increase and 29 decrease, so the number of the decrease-expected species is three times more than that of the increase-expected species.

하천의 지형학적 인자와 식생종수의 관계 -한강수계를 중심으로-

이광우,김태균,심우경 한국조경학회 2002 韓國造景學會誌 Vol.30 No.3

The purpose of this study was to develop prediction models for plant species abundance by stream restoration. Generally the stream plant is affected by stream gemophology. So in this study, the relationship between the vegetation abundance and stream gemophology was developed by multiple regression analysis. The stream characteristics utilized in this study were longitudinal slope, transectional slope, micro-landforms through the longitudinal direction, riparian width and geometric mean diameter and biggest diameter of bed material, and cumulated coarse and fine sand weight portion. The Pyungchang River with mountainous watershed and the Kyungan stream and the Bokha stream in the agricultural region were selected and vegetation species abundance and stream characteristics were documented from the site at 2~3km intervals from the upper stream to the lower. The Models for predicting the vegetation abundance were developed by multiple regression analysis using SPSS statistics package. The linear relationship between the dependant(species abundance) and independant(stream characteristics) variables was tested by a graphical method. Longitudinal and transectional slope had a nonlinear relationship with species abundance. In the next step, the independance between the independant variables was tested and the correlation between independant and dependant variables was tested by the Pearson bivariate correlation test. The selected independant variables were transectional slope, riparian width, and cumulated fine sand weight portion. From the multiple regression analysis, the $R^2$for the Pyungchang river, Kyungan stream, Bokga stream were 0.651, 0.512 and 0.240 respectively. The natural stream configuration in the Pyungchang river had the best result and the lower $R^2$for Kyunan and Bokha stream were due to human impact which disturbed the natural ecosystem. The lowest $R^2$for the Bokha stream was due to the shifting sandy bed. If the stream bed is fugitive, the prediction model may not be valid. Using the multiple regression models, the vegetation abundance could be predicted with stream characteristics such as, transection slope, riaparian width, cumulated fine sand weigth portion, after stream restoration.

Projection of Distribution and Abundance of Korean ants based on Climate Warming

Tae-Sung Kwon,Cheol Min Lee,Jung-Hwa Chon 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.04

Distributions of ants are mainly dependent on temperature. Hence, global warming would lead to shifts of distribution and abundance in ants. We surveyed ants at 366 forest sampling sites in South Korea using pitfall traps to predict change of ant abundance. Abundances of ant species were projected on the projected temperature based on A1B climate scenario. Common species (> 10 % occurrence) were analyzed on the relationship between abundance and temperature, and 16 species of the common species were selected for projection of abundance owing to future climate warming. Abundance of the selected species were projected on 900 m2 grid cells in 2011 and 2060 using GIS tool. In the projection, 11 species are predicted to decrease in 2060, whereas 5 species are predicted to increase. Myrmica kotokui, a most dominant highland species is expected to decrease up to 2.5% of current abundance in 2060, whereas Pachycondyla chinensis is expected to increase up to 264%. This abrupt change of ants would lead to cascade effects on other organisms such as insects, plants, mushrooms, and birds, which would disturb various functions and services of forest ecosystems.