Erratum to: Effects of environmental and biological conditions on the recruitment and growth of the Manila Clam Ruditapes philippinarum on the West Coast of Korea

Spat settlement (spat density, recruitment, and mortality) of edible oysters Crassostrea spp. was estimated for three sites (Nunia Chara [NC], Chowfoldandy [CD], and Sonadia Island [SI]) located along the Cox’s Bazar coast of Bangladesh from February 2019 to January 2020 by deploying shellstrings. Field observations were made every 15 d to understand the monthly variation of oyster spat settlement more precisely. Environmental variables varied significantly with the study site × month interaction or across study sites and months. Gonadal maturation and spawning of oysters may depend on certain environmental conditions, which were greatly influenced by seasonality, especially the monsoon. Spat density, recruitment, and mortality rates were significantly different with the study site × month interaction. The NC site offered higher spat density and recruitment than CD and SI during most months; spat density was lower due to increased mortality during the monsoon (late May to mid-October) at all sites. Spat density was positively related to salinity, pH, and total suspended solids but negatively related to temperature and high- and low-tide water depths. Recruitment was positively related to salinity and negatively related to low-tide water depth. Spat mortality was positively related to high-tide water depth but negatively related to low-tide water depth. Eight different groups of fouling organisms were observed during the study, which could affect spat settlement. Most interestingly, oyster drills at NC and SI and marine macrophytes and bushlike organisms at CD and SI could contribute to increased mortality during the monsoon. This study showed that none of the three sites would be potential locations for spat collection on shellstrings during the monsoon; however, if avoiding the monsoon, NC has a higher potentiality of allocation for spat collection both for commercial farming and oyster restoration efforts.

Mytilus galloprovincialis is an ecosystem engineer that provides habitat and generates environmental heterogeneity, increasing local biodiversity. Moreover, it is an economically important species representing 14% of the global production of marine bivalves. Natural drivers and the increase of anthropogenic pressures, such as sediment stress, influence its populations on rocky shores. The objective of this study was to explore the spatial-temporal patterns of different M. galloprovincialis attributes along the north of Portugal. For that purpose, six rocky shores were selected and sampled six times along the year 2019. The percentage of cover, density, spat density, condition index, clump thickness, size classes and clump sediment content were considered. Results showed the lack of seasonality in M. galloprovincialis along the north coast of Portugal. However, density, spat stage, clump thickness, condition index and size classes showed some variability among dates and shores. The percentage cover and sediment content only significantly differed among shores. Our results indicated an absence of seasonality for all the studied variables, probably because temperature was always within the optimum range for this species and the abundance of food supply in the study area independently of the season. The accumulated sediment on mussel clumps did not show any temporal variability with only significant differences among shores. The accumulated sediment was composed mainly by medium and coarse sand and it was correlated with mussel average size, condition index, but especially with the mussel clump thickness.

To elucidate the factors that influence the interannual variation in the density of cultured Japanese scallop ( Mizuhopecten yessoensis ) spat, we analyzed the relationship between spat density (Ds), monthly chlorophyll a (chl a) concentration, water temperature, and adductor muscle weight of spawners over 15 years (1992–2006) in Funka Bay (Japan) on the western North Pacific Ocean. The interannual variation of spat density was best explained by a campaniform model that used chl a concentration in February ([chl]Feb) and a categorical variable that indicates whether growth of spawners in a year is low or not as independent variables (R2 = 0.91). The gonadosomatic index increased fastest in February. Low growth years were detected as outliers in the Ds – [chl]Feb relationship and were characterized by an average weight of adductor muscles in February of <12 g. Therefore, food availability during gonadal development and growth conditions of spawners were the main factors determining spat density. The proportion of ovary necrosis was high in the years of low [chl]Feb and low growth. Those years corresponded with El Niño and La Niña years, respectively. Thus, global climatic anomalies apparently affect reproduction of the scallop in Funka Bay.

This is the first study of seasonal changes in gonad development and tissue biochemical composition of the cockle Fulvia mutica in Cheonsu Bay off the west coast of Korea. Gametogenesis commenced in December when the surface water temperature was 9.1°C. In May, the first discharge of oocytes was observed, and spawning continued until October. The condition index (CI), a ratio of tissue dry weight to shell dry weight, increased gradually from late May to July and declined dramatically in August and September, indicating that active discharge of gametes occurred in the bay during this period. Histology and the CI suggested that F. mutica spawning in Cheonsu Bay is continuous from early summer to early fall, with two spawning peaks in June and July, and September and October. All cockles examined in November were sexually inactive. The relatively low CI recorded in late fall to mid winter (November to January) coincided with high levels of ash and low levels of lipids and carbohydrates in the tissue, whereas protein levels remained unchanged. The observed spawning pattern of F. mutica in Cheonsu Bay suggests that the currently established timing for fishing closure, from July to September, should be expanded from June to October to protect earlyspawning broodstocks. This change may secure recruitment and lead to a subsequent increase of the wild cockle population in the bay.

Sedimentation patterns of tidal flats along the Korean west coast have long been known to be largely controlled by the monsoon climate. On the other hand, much less is known about the effect of the monsoon on sedimentation in coastal embayments with mouths of different geographic orientations. Good examples are Hampyeong and Yeoja bays along the west and south coasts, respectively. Both have narrow entrances, but their mouths open toward the northwest and the south, respectively. With mean tidal ranges of 3.46 and 3.2 m, respectively, the two bays experience similar tidal regimes and are hence excellent candidates to compare the effect of different exposure to the same regional monsoon climate on their respective sediment distribution patterns. The winter monsoon, in particular, is characterized by strong northwesterly winds that directly impact the west coast, but blow offshore along the south coast. For the purpose of this study, surficial sediment samples were collected from intertidal and subtidal flats of the two bays, both in summer and winter. Grain-size analyses were carried out by sieving (sand fraction) and Sedigraph (mud fraction). In the case of Yeoja Bay, the sediments consist mostly of mud (mean grain sizes of 5.4 to 8.8 phi). Seasonal changes are very subtle, the sediments being slightly coarser in summer when silt-dominated sediments are supplied by two streams to the northern parts of the bay in response to heavy rainfall. With the exception of the deeper tidal channels, Yeoja Bay is characterized by a thick mud blanket the year round, which is modulated by processes associated with the summer monsoon that predominantly blows from the east. Textural parameters suggest severely restricted sediment mixing on the subtidal and intertidal flats, the overall low energy situation preventing sands from reaching the tidal flats. The sediments of Hampyeong Bay, by contrast, are characterized by a distinct shoreward fining trend. Mean grain sizes average around –2.2 phi at the mouth and 8.2 phi near the shore of the inner bay. The textural relationships suggest progressive mixing between two hydraulic populations, the overall higher energy situation allowing sands to be transported onto the tidal flats in winter. In addition, a clear seasonal signal indicating deposition in summer and erosion in winter is observed, the latter probably being controlled by waves generated by strong northwesterly winds of the winter monsoon. The contrasting energy regimes controlling sediment distribution in the two bays are particularly well reflected in ternary diagrams of sand/silt/clay ratios and bivariate plots of textural parameters. The results clearly demonstrate that tidal sedimentation along the west coast of Korea is controlled by the more energetic winter monsoon, whereas along the south coast it is modulated by the less energetic summer monsoon. As a consequence, distinct seasonal changes are particularly pronounced along the west coast, whereas these are more subtle along the south coast. The orientation of bay mouths relative to the direction of wind associated with the summer and winter monsoon is thus identified as the main reason for the completely different sedimentation patterns observed on the subtidal and intertidal flats of the two bays.

Gonad intrusion of the larval trematodes often results in substantial damage to the reproductive capacity of some economically important marine bivalves. Such detrimental impacts of the larval trematode infection are observed in Manila clam Ruditapes philippinarum in the coastal Yellow Sea, although the effects on the host’s reproduction are poorly understood. Accordingly, this study attempts to understand the impacts of parasitism on clam reproduction using histology. Of the 1,255 adult clams collected in early June from a tidal flat on the west coast of Korea, 68 individuals (5.4%) were infected by three different larval trematodes, including Cercaria tapidis, Cercaria pectinata, and Parvatrema duboisi. Histology revealed that the uninfected clams were in the late developing or ripe stage, exhibiting fully developed gametes in the expended follicles. In contrast, clams infected by the larval trematode showed retarded gonad maturation. Some of those clams remained sexually indifferent (13/68 infected clams) or early developing (9/68 infected clams). We categorized the infection level into uninfected (0), light (1), moderate (2), heavy (3), and very heavy (4), according to the area of sporocysts occupying the histology section. The image analysis indicated that approximately 50% of the infected clams were in “heavy” and “very heavy” conditions, and they occupied 16.7% and 26.9% of the total cross-section area, respectively. The nonparametric Kruskal–Wallis’s test and the post-hoc Tukey’s test indicated that the condition index (CI) of clams in heavy and very heavy infection were significantly lower than uninfected clams. In conclusion, the larval trematodes infected about 5.4% of the clam population in the tidal flat on the west coast of Korea, and we estimated that 32.4% of the infected clams might fail to reproduce during a spawning period due to the severe infection.

To study the difference in growth characteristics between intertidal and subtidal eelgrass Zostera marina populations, environmental factors and changes in tissue carbon (C) and nitrogen (N) contents in eelgrass from the lower intertidal and upper subtidal zones were surveyed monthly in the Seomjin Estuary from May 2003 to December 2004. Water temperatures, water column nutrient concentrations, sediment pore water, and ammonium and phosphate concentrations showed no significant differences between intertidal and subtidal zones. Sediment pore water nitrate+nitrite concentrations were slightly higher in the intertidal zone than in the subtidal zone. Average monthly exposure times in the intertidal and subtidal zones were <TEX>$42.4{\pm}5.8h\;month^{-1}$</TEX> and <TEX>$15.3{\pm}3.5h\;month^{-1}$</TEX>, respectively. Eelgrass leaf N content decreased from March to August and increased from September to February in the subtidal zone, whereas these trends were not observed in the intertidal zone. Eelgrass rhizome C content increased from April to September and decreased from October to March in the subtidal zone, whereas those tendencies were not recorded in the intertidal zone. Eelgrass rhizome C:N ratios showed a strong reverse trend to leaf C:N ratios in the subtidal zone, but these tendencies were not observed in the intertidal zone. The effects of exposure appeared to cause no seasonal trend in eelgrass tissue C and N content or C:N ratios in the intertidal zone in the Seomjin Estuary.

Aquaculture planning for suspended bivalve farming systems: The integration of physiological response of green mussel with environmental variability in site selection

To examine the growth dynamics of eelgrass, Zostera marina, in the intertidal zone of Seomjin Estuary, Korea, we surveyed environmental factors such as water temperature, underwater irradiance, tidal exposure, and nutrient concentrations in the water column and sediment pore water in relation to the shoot density, biomass, morphological characteristics, and growth of Z. marina inhabiting the upper and lower intertidal zones. The survey was conducted monthly from January 2003 to December 2004. The water temperature of the two areas displayed seasonal fluctuations. Underwater irradiance was significantly higher in the upper intertidal zone than in the lower intertidal zone. Tidal exposure was also markedly longer in the upper intertidal zone than in the lower intertidal zone, whereas tidal exposure was highest in the spring and lowest in the summer in both areas. Water column NH4+ and sediment pore water NO3−+NO2− concentrations were significantly higher in the upper intertidal zone than the lower intertidal zone. The eelgrass shoot density, biomass, morphology, and leaf productivity were significantly higher in the lower intertidal zone than in the upper intertidal zone. Both areas displayed a clear seasonal variation depending on changes in water temperature. However, leaf turnover time was significantly shorter in the upper intertidal zone than in the lower intertidal zone, with a higher turnover rate in the upper intertidal zone. Compared to the seagrasses in the lower intertidal zone, those in the upper intertidal zone showed more effective adaptations to the stress of long tidal exposure through downsizing and increased turnover time. These results suggest that tidal exposure, coupled with desiccation stress, can be a limiting factor for seagrass growth in the intertidal zone, along with underwater irradiance, water temperature, and nutrient availability.

BackgroundOver the past few decades, mass mortality events of Manila clams have been reported from several tidal flats on the west coast of Korea during hot summers. During such mortality events, once clams simultaneously surface, they fail to re-burrow, perishing within a week. The present study aimed to identify the possible causes of the mass mortality of this clam species by investigating the Perkinsus olseni parasite burden and immune parameters of surfaced clams (SC) and normal buried clams (NBCs) when sea water or sediment temperature in the study area varied from 25 °C to 34 °C from late July through mid-August 2015.ResultsWe collected 2 groups of clams distributed within a 10-m2 area when a summer clam mortality event occurred around Seonyu-do Island on the west coast of Korea in 2015. The clams were collected 2 days after they surfaced on the sediment and still looked healthy without any gaping. The clams were transported to the laboratory, and we compared P. olseni infection intensity and cell-mediated hemocyte parameters between the NBCs and SCs. SCs showed significantly higher levels of P. olseni burden, lower condition index, and lower levels of cell-mediated immune functions than those of NBCs.ConclusionsOur study suggests that high P. olseni infection weakens Manila clams’ resistance against thermal stress, causing them to surface. We surmise that the summer mass mortality of Manila clams on the west coast of Korea is caused by the combined effects of high P. olseni infection levels and abnormally high water temperature stress.

Impact of derelict fishing gear on the seafloor integrity and benthic communities in the macrotidal flats from northern Gyeonggi Bay, west coast of Korea

The ecophysiological characteristics of the oyster Crassostrea gigas in Taean area, west coast of Korea, were investigated after main spawning season from September 2011 to January 2012 to confirm the recovery process of condition. The cupped oysters, from 4 different off-bottom culture areas were compared the gonad indices, histological analysis combined with measurement of RNA/DNA contents and ratios in gonad of each sex were undertaken. To evaluate the health condition of oyster after spawning, the RNA/DNA ratio in adductor muscle, fatness and condition index (CI) were used. The results showed that cupped oysters cultured in Uihang coastal area were different physiological aspects than other experiment areas, namely continuously decreasing RNA/DNA content and ratio in adductor muscle, lowest CI and fatness. Oysters cultured in Iwon Station 1 and 2 showed fast recovery in RNA/DNA, increase in fatness and CI during post-spawning stage until October rapidly and there after it decreased. Oysters in Shinduri showed rapidly decrease in fatness and CI until October. On the contrary to this factors, RNA/DNA ratio in adductor muscle increased as like protein until October. Partially spawning season could be observed until December in Shinduri and Iwon Station 1.

&amp;lt;p&amp;gt;Many of macrotidal beaches contain a series of shore-parallel sandbars, developed under relatively low-energy conditions. The morphology of the multiple intertidal bars is highly dynamic, in response to wave climates. Four lines of sandbars on ca. 500 m streches of intertidal zone, Shinduri, west coast of Korea, are found in a semi-closed embayed beach with a tidal range of over 6 m. The seasonal dynamics are, however, poorly documented. In order to understand the seasonal morphological changes and their hydrodynamic forcing, three-years of topographic survey using a VRS-GPS system and drone photogrammetry have been conducted on six monitoring transects. An ADV and ADCP was additionally deployed to collect wave data on a bar crest. Mean grain sizes show generally shoreward coarsening trend, ranging from 2.0 to 2.75 phi. Sediments became coarser in summer, but finer in winter, which are contrasting to other beaches in the west coast of Korea. Wave data show strong seasonality, high waves in winter and much gentler waves in summer, suggesting the study area experienced by monsoon climate. Topographic surveys show that four ridge and runnel systems are prominent during summer, whereas, in winter, they are insignificant. From the spring to summer season multi-bar starts to form under low-energy waves, leading to bar crest accretion in all profiles measured. Conversely, during the fall to winter seasons, signicant of cross-shore bar migrations and hence flattening of crests of sandbars have been observed due to dramatic increase in wave energy. This signifies that local wave condition is more important for maintaining patterns of multiple bars even in macrotidal setting.&amp;lt;/p&amp;gt;

Environmental conditions can strongly influence the growth performance of pearl oysters and affect pearl farm production schedules. Growth and condition index (CI) of two age cohorts of Pteria penguin were measured for 13 months to investigate differences in growth performance between four culture sites within the northern (Vava’u) and southern (Tongatapu) island groups of the Kingdom of Tonga. Environmental conditions were also measured at culture sites and used to explore potential effects on oyster growth and condition. Between island groups, growth performance of P. penguin was superior at northern sites and was most strongly related to higher water temperatures at these sites. Within the southern island group, growth performance varied significantly between sites and may be driven by differences in wave energy. Monthly growth rates (GM) of P. penguin also showed significant temporal variation related to age and environmental conditions. This study demonstrated significant variation in the growth performance of P. penguin at latitudinal and local scales and suggests that in oligotrophic marine environments with minimal terrestrial inputs, such as Tonga, water temperature and wave exposure may be the primary environmental conditions influencing the growth performance of P. penguin. This study therefore recommends that optimal culture sites for P. penguin in Tonga are characterized primarily by warmer water temperatures (25–30°C) and low wave exposure (&amp;lt;15 joules m2 day–1). Culture of P. penguin at sites with more suitable environmental conditions enables pearl production to begin up to 34.2 % (6.5 months) earlier than at less-suitable sites and this may greatly influence mabé pearl farm profitability and feasibility.

Research Article| June 01, 2015 Morphodynamics of Tidal Channels In the Open Coast Macrotidal Flat, Southern Ganghwa Island In Gyeonggi Bay, West Coast of Korea Kyungsik Choi; Kyungsik Choi School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea e-mail: tidalchoi@snu.ac.kr Search for other works by this author on: GSW Google Scholar Joo Hee Jo Joo Hee Jo School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea Search for other works by this author on: GSW Google Scholar Author and Article Information Kyungsik Choi School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea Joo Hee Jo School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea e-mail: tidalchoi@snu.ac.kr Publisher: SEPM Society for Sedimentary Geology Received: 01 Sep 2014 Accepted: 10 Mar 2015 First Online: 09 Mar 2017 Online ISSN: 1938-3681 Print ISSN: 1527-1404 Copyright © 2015, SEPM (Society for Sedimentary Geology) Journal of Sedimentary Research (2015) 85 (6): 582–595. https://doi.org/10.2110/jsr.2015.44 Article history Received: 01 Sep 2014 Accepted: 10 Mar 2015 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Kyungsik Choi, Joo Hee Jo; Morphodynamics of Tidal Channels In the Open Coast Macrotidal Flat, Southern Ganghwa Island In Gyeonggi Bay, West Coast of Korea. Journal of Sedimentary Research 2015;; 85 (6): 582–595. doi: https://doi.org/10.2110/jsr.2015.44 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Sedimentary Research Search Advanced Search Abstract: Morphodynamics of intertidal channels were monitored in order to understand their implication on the architecture of inclined heterolithic stratification (IHS) in the open-coast Yeochari macro tidal flat on southern Ganghwa Island in Gyeonggi Bay, west coast of Korea. The tidal flat is divisible into narrow salt marshes in the upper intertidal zone, a concave-up upper to middle intertidal zone with small tidal creeks, and a channelized lower intertidal zone. Channels in the lower intertidal zone are 200–600 m wide and 1–2.5 m deep at bankful stage. They are sinuous in planform and have well-defined point bars and cutbanks. IHS is exposed along the cutbanks. High-precision leveling of the tidal channel bank unveiled that a point bar in the lower intertidal zone migrated about 400 m in 39 months. Channel migration is pronounced during the summer rainy season, when the point bar migrated as fast as 40 m per month, which led to rapid sediment accumulation of as much as 40 cm per month. In contrast, channel migration rate during winter is notably reduced, down to less than 1 m per month. Point-bar geometry alternates between a concave-up profile in summertime and a convex-up profile during the remainder of the year. Enhanced ebb currents during the rainy season, due to increased runoff discharge caused by heavy precipitation, accelerated point-bar migration. Remarkable rill erosion induced by heavy precipitation especially during low tide led to the rapid accumulation of sediment at the lower part of the point bar and the channel base, creating concave-up point-bar geometry. During the remainder of the year, the point bar retains a convex-up profile by continued sedimentation with insignificant rill erosion. Wave activity, particularly during winter, seems to facilitate deposition in the upper part of the point bar by providing more sediment into the channel. The present study illuminates the fact that the stratigraphic architecture of IHS of intertidal origin is controlled largely by monsoonal weather and to a lesser degree by tidal process even in a macrotidal environment. Careful examination of IHS geometry may hint at the depositional setting in terms of tidal frame (intertidal versus subtidal) and climate regime (monsoonal versus non-monsoonal). You do not have access to this content, please speak to your institutional administrator if you feel you should have access.