• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.1
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• pp.9-16
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• 2013

The growth and production of Aulichthys japonicus (6.70~15.32 cm TL) were investigated in an eelgrass bed of Dongdae Bay, Korea throughout 2006. A total 888 A. japonicus were collected with a small beam trawl. Growth in fish total length was expressed by the von Bertalanffy's growth equation as: $L_t=24.8257(1-e^{-0.5583(t+0.4816)})$. The densities, biomass, daily, annual production, and P/B ratio were $0.01{\pm}0.009/m^{-2}$, $0.17{\pm}0.16g/m^2$, $0.00006{\pm}0.00006g$ AFDW/$m^2$/day, 0.02g AFDW/$m^2$/yr, and 0.12, respectively. Monthly variation in production of A. japonicus was large; the peak occurred at July, September and November 2006 (0.000182, 0.000127 and 0.000123 g AFDW/$m^2$/day), where as the lowest value was 0.000003g AFDW/$m^2$/day at April and May 2006. Monthly change in production of A. japonicus was positive correlated with number of individuals, biomass and growth rate.

• Korean Journal of Environmental Biology
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• v.33 no.1
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• pp.83-91
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• 2015

This study is measured the change of chlorophyll-${\alpha}$ concentration and phytoplankton density, the grazing rates (GR) and pseudofaeces production (PFP), by grazing of freshwater apple snail, Pomacea canaliculata, to investigated that the snails are able to control of phytoplankton bloom. The experiments are performed to evaluate the GR and PFP at different conditions such as incubation time (0, 2, 4, 6, 8, 10 and 12 hr), shell height (1.0 to 4.0 cm, n=108), snail density (1, 1.5, 2.5, 3.5 and 5 indiv. $L^{-1}$) and food concentration (200, 400, 600, 800 and $1000{\mu}g$ $L^{-1}$). Regarding feeding time, the highest GR (2.5 L. $gAFDW^{-1}h^{-1}$) and PFP (15.3 mg $AFDW^{-1}$) showed at 4 hr after snail stocking, respectively. The snail, smaller than 1.5 cm in body size, showed the highest of GRs (2.54 L. $gAFDW^{-1}h^{-1}$) for the initial period (2 hr of stocking), compared to those greater than 1.5 cm, which showed a stable FR, higher than 0.099 L. $gAFDW^{-1}h^{-1}$. Upon snail density effect, the density of 5 indiv. $L^{-1}$ induced the most effective inhibition on phytoplankton biomass with the highest PFP. On the food concentration, the highest GR (0.54 L. $gAFDW^{-1}h^{-1}$) and PFP (8.5 mg $gAFDW^{-1}$) were induced at the level of $600{\mu}g$ $L^{-1}$, respectively. We checked that it is possible to control of phytoplankton bloom by the grazing of apple snail as well as Reeve. However, it required a through research for the remove of pseudofaeces and 2nd problem by the decomposition of the organic materals.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.461-467
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• 2014

The growth and production of Pseudoblennius cottoides (1.80~10.01 cm TL) were investigated in an eelgrass bed of Dongdae Bay, Korea throughout 2006. A total 702 P. cottoides were collected with a small beam trawl. Growth in fish total length was expressed as: $TL=0.0539d^{0.9105}$. The relationships between total length body weight was estimated as $W=0.0079TL^3.1103$. The densities, biomass, daily, annual production, and P/B ratio were $0.06{\pm}0.062/m^2$, $0.10{\pm}0.144g/m^2$, $0.0005{\pm}0.0006g\;AFDW/m^2/day$, $0.1833g\;AFDW/m^2/year$, and 1.813, respectively. Monthly production of P. cottoides were greatly peak in May, July and September (0.0029, 0.0031 and $0.0019g\;AFDW/m^2/day$) when the biomass was high, and the lowest value in December (0.00004g AFDW/m^2/day) when the biomass was low. Monthly change in production of P. cottoides was positively correlated with biomass and temperature.

• Ocean and Polar Research
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• v.43 no.2
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• pp.89-98
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• 2021

The seagrass habitats are a highly productive marine ecosystem which provides nursery ground and shelter for many fish and invertebrate species. Pholis nebulosa (Temminck & Schlegel, 1845) is one of the most abundant seagrass fishes in the coastal waters of Korea. The estimation of fish production is key for devising conservation measures and ensuring fish resources sustainability. A total 894 P. nebulosa ranging from 3.83 to 26.5 cm total length (TL) were collected monthly in 2006 with a small beam trawl in a seagrass bed of southern Korea. Growth parameters of P. nebulosa were estimated using the von Bertalanffy growth model, and production was estimated using a general equation which relates daily fish production to ash-free dry weight (AFDW), biomass, and water temperature. The von Bertalanffy's growth equation was estimated as: L_t = 28.3823(1-e^{-0.7835(t+0.9864)}). The densities, biomass, daily, annual production, and P/B ratio were 0.069±0.061/m^-2, 1.022±0.621 g/m², 0.005±0.004 g AFDW/m²/day, 1.676 g AFDW/m²/yr, and 1.641, respectively. Monthly variation in production of P. nebulosa peaked during March and April 2006 (0.0139 and 0.0111 g AFDW/m²/day), whereas the lowest value of 0.0005 g AFDW/m²/day was in December. Monthly change in production of P. nebulosa was positively correlated with biomass and condition factor. Our results will contribute to the conservation of seagrass ecosystems, which are still undisturbed in the study area.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.77-85
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• 2008

Grazing rates (GR) and pseudofaeces production (PFP) of native snail, Chinese mystery snail (Cipangopaludina chinensis malleata Reeve) on natural colonial morphs of Microcystis aeruginosa was measured. C. chinensis was collected from the upstream of the Geum River (Boryeong, Korea), where they co-habituated with Unio douglasiae and Lanceolaria acrorhyncha. The experiments were performed to evaluate the GR and PFP at different conditions such as; incubation time (1, 3, 5, 7, 9 and 11 hr), body size (3 to 6.1 cm, n=28), snail density (0.5, 1, 1.5 and 2.0 ind. $L^{-1}$) and prey concentration (168.3, 336.7, 505.0 and $673.0{\mu}g\;Chl-{\alpha}L^{-1}$). All experiments were triplicated, and conducted in transparent acrylic vessel (3L in volume). Regarding feeding time, a highest GR (0.538L $gAFDW^{-1}h^{-1}$) and PFP $(7.18mgAFDW^{-1})$ appeared at 1hr and 7hr after snail stocking, respectively. Interestingly, the snail, smaller than 4.5cm in body size, showed a wide range of GR ($-4.173{\sim}1.087L\;gAFDW^{-1}h^{-1}$) for the initial period (1 and 4hrs of stocking), compared to those greater than 4.5cm, which showed a stable FR, higher than 0.5L $gAFDW^{-1}h^{-1}$. Upon density effect, the density of 1.5 ind. $L^{-1}$ induced the most effective inhibition on Microcystis biomass with highest PFP. On the prey concentration, highest GR (0.897L $gAFDW^{-1}h^{-1}$) and PFP (3.67 mg $gAFDW^{-1}h^{-1}$) were induced at the level of $168.3{\mu}g\;Chl-{\alpha}L^{-1}$ and $673{\mu}g\;Chl-{\alpha}L^{-1}$, respectively. GR and PFP of this freshwater snail on the cyanobacterial bloom (M. aeruginosa) varied with the feeding conditions, and they were comparatively high for a short period of time less than 7hrs regardless of the stocking condition. Our results suggest that this freshwater snail has a potential to control cyanobacterial bloom when provided with suitable condition.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.50-60
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• 2008

We performed the experiment to evaluate the effect of different DO concentrations (0.5, 4.5 and 9.0 $mgO_2L^{-1}$) and water depths (20, 50 and 80 cm) on the filtering rate, mortality, and pseudifeces production of Unio douglasiae against the cyanobacterial bloom (mainly Microcystis aeruginosa). A solitary-living bivalve U. douglasiae was collected in the upstream region of the North Han River (Korea). The harvested mussels were carefully transferred to the laboratory artificial management system, which was controlled temperature $(18{\pm}2^{\circ}C)$, flow rate (10L $h^{-1}$), food $(Chlorella^{TM})$, sediment (pebble and clay), light intensity (ca. $20{\mu}mol$ photons), and photocycle (12 L : 12 D). In the field observation, the mussel mortality was significantly correlated with water temperature, pH and DO concentration (P<0.05). The mortality was decreased with water depth; 65, 90, 80% of mortality at 20, 50, 80 cm water-depth, respectively. Filtering rate (FR) showed the highest value at 50 cm water depth, and thereby the concentration of chlorophyll-${\alpha}$ decreased continuously by 94% of the control at the end of the experiment. In contrast, FR decreased by 34% of the initial concentration at 20 cm water depth. Over the given water-depth range, the mussel FR ranged from $0.15{\sim}0.20L\;gAFDW^{-1}hr^{-1}$ during the 18hrs of experiment, and thereafter, they appeared to be approximately 0.11, 0.26 and 0.30 L $gAFDW^{-1}hr^{-1}$ at 20, 50 and 80cm water depth, respectively. FR was highest with the value of 0.46L $gAFDW^{-1}hr^{-1}\;at\;0.5mgO_2 L^{-1}$ at the early stage of the experiment, while it increased with DO concentration. Maximum pseudofaeces production was 11.2 mg $gAFDW^{-1}hr^{-1}\;at\;9.0mgO_2L^{-1}$. Our results conclude that U. douglasiae has a potential to enhance water quality in eutrophic lake by removing dominant cyanobacteria, but their effects vary with environmental parameters and the water depth at which they are located.

• Journal of Practical Agriculture & Fisheries Research
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• v.14 no.1
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• pp.107-115
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• 2012

In juvenile size, the maximum clearance rate and ingestion rate were 15mm, which is the 70.8 mL/h, 4245.0×104cells/h, respectively. But the lowest clearance rate and ingestion rate were found at 5mm, which is the 4.1 mL/h, 246.0×104cells/h, respectively. The highest clearance rate and ingestion rate of AFDW seen at 7.5mm, with 3.3 mL/mg AFDW/h, 196.0×104cells/mg AFDW/h, respectively. According to the results of water temperature, clearance rate and ingestion rate were lowest at 10℃, showing the 0.3 mL/h, 20.3×104cells/h, respectively. The highest clearance rate and ingestion rate were 25℃, which is the 16.6 mL/h, 993.4×104cells/h, respectively. But in 30℃, clearance rate and ingestion rate decreased to the 12.9 mL/h, 772.6×104cells/h, respectively. With respect to the food density, the experiment groups with 30×104 cells/mL and 240×104 cells/mL showed the clearance rate of 21.1 mL/h and 2.3 mL/h, respectively. But the experimental group with 120×104 cells/mL or more showed decreased clearance rate. While, the maximum ingestion rate was at 60×104 cells/m, showing the 876.2×104cells/h.

• Korean Journal of Ecology and Environment
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• v.38 no.1 s.110
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• pp.1-10
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• 2005

Macroinvertebrates from a first order stream at Mt Jumbong, Kangwon-do, was examined for their abundance and biomass. Sampling was done by using a pipe sampler (${\phi}$ 20 cm) for 11occasions (n = 5) at 4${\sim}$6 weeks intervals during November 1997 through October 1998. Water temperature and electronic conductivity of the study stream ranged $0\;{\sim}\;14^{\circ}C$ and 15${\sim}$25 ${\mu}s$/cm, respectively. During the study, 53 insect taxa and 3 non-insect taxa were collected. Annual mean number of individuals (${\pm}$1 SD) was 77741${\pm}$69232${\cdot}$m$^{-2}$ ${\cdot}$yr$^{-1}$, being high in winter (${\pm}$1 SD) (December: 171178${\pm}$130468 $m^{-2}$) and low in summer (${\pm}$ 1 SD) (June: 29872${\pm}$13078 $m^{-2}$). Non-predatory subfamilies of Chironomidae and Nemoura sp. occupied 53.3% and 21.8% of annual abundance. Annual mean biomass was 10g${\cdot}$m$^{-2}$${\cdot}$yr$^{-1}$ in ash free dry weight (AFDW), being high in late winter (February: 16 gAFDW $m^{-2}$.) and low in summer (June: 3 gAFDW $m^{-2}$). Gammarus sp. represented 39.8% of the total biomass and was followed by non-predatory subfamilies of Chironomidae (15.2%) and Hydatohylax sp. (8.5%, Limnephilidae: Trichoptera). Since the non-predatory subfamilies of chironomidae were composed of many species, Nemoura sp. was the most abundant taxon. However, Cammarus sp. was surely the most important taxon to the functional aspects of this first order stream ecosystems.

• The Korean Journal of Malacology
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• v.14 no.2
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• pp.121-130
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• 1998

Studies on the distribution and growth of the mud mussel, Musculista senhousia, were carried out in the mud-tidal flat near Mokpo from August 1996 to July 1997. The patch distribution of the mussel was observed in the middle part of the tidalflat during the study period. Annual mean density was 8,215${\pm}$1,394 ind./m2 and annual mean biomass was 1,966.43${\pm}$668.49 g TWwt/m2 in total wet weight, 760.04${\pm}$279.13 gMWwt/m2 in meat wet weight, 209.93 ${\pm}$ 49.41 gMDwt/m2 in meat dry weight, and 109.66${\pm}$58.78 gAFDW/m2 in ash-free dry weight. The monthly mean size of shell length varied from 11.00 mm to 16.97 mm. Relationship between shell length (SL) and shell height (SH) showed a positively significant regression (SH=0.482SL+0.791, R2=0.940, P<0.001). Regressions of total wet weight (TWwt) (TWwt=7.601${\times}$10-5SL3.052, R2=0.905, P<0.001), and meat wet weight (MWwt) (MWwt=1.127${\times}$10-5${\times}$SL3.404, R2=0.784, P<0.001) on shell length were positively allometric, with highly significant correlation coefficient. The relationships between SL and meat dry weight (MDwt), and AFDW were MDwt=9.813${\times}$10-6${\times}$SL2.928 (R2=0.421), and AFDW=1.015${\times}$10-5${\times}$SL2.922(R2=0.810), respectively. The condition factor of the mussel has been increased from March and formed a peak in July and August. It was sharply dropped in September. These results suggest that the gonadal development of the species commenced to be occurred in spring and that main spawning occurred between August and September.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.61-67
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• 2008

This study was conducted to evaluate filtering rate (FR) and pseudofeces production (PFP) of a freshwater filter-feeding bivalve, Unio douglasiae, on a toxic cyanobacterium (Microcystis aeruginosa). The experiments were conducted under the various conditions of water temperature $(5{\sim}35^{\circ}C)$, mussel size $(5.6{\sim}13.3cm)$ and food con centrations $(49{\sim}491{\mu}g\;Chl-{\alpha}L^{-1})$. Among the applied temperature, the maximum FR $(0.41L\;gAFDW^{-1}hr^{-1})$ and PFP (0.47mg $gAFDW^{-1}hr^{-1}$) were observed at 15 and $25^{\circ}C$, respectively. Both weight-based FR and PFP were not correlated with the mussel size, and the values lied in a limited range with some degree of variation. Likewise, no significant relations between FR and PFP was observed in the mussel size. The FR values were negatively correlated with food concentration, while PFP showed positive correlation. Among the applied food concentrations, the maximum FR (0.34L $gAFDW^{-1}hr^{-1}$) and PFP (0.06mg $gAFDW^{-1}hr^{-1}$) appeared in $113{\mu}g\;Chl-{\alpha}L^{-1}$ and $491{\mu}g\;Chl-{\alpha}L^{-1}$, respectively. These results indicate that the grazing of Unio douglasiae are affected by various parameters, and it may be applied as an effective biofilter to inhibit Microcystis bloom under appropriate application. However, further studies on the fate of excreted pseudofeces are needed to understand their possibility of stimulating nuisant algal growth.