Macrophthalmus Japonicus Research Articles

Predicting habitat associations of five intertidal crab species among estuaries

Intertidal crab assemblages that are active on the sediment surface of tropical estuaries during tidal exposure play an important role in many fundamental ecosystem processes. Consequently, they are critical contributors to a wide range of estuarine goods and services. However, a lack of understanding of their spatial organization within a large landscape context prevents the inclusion of intertidal crabs into generally applicable ecological models and management applications. We investigated spatial distribution patterns of intertidal crabs within and among eight dry tropical estuaries spread across a 160 km stretch of coast in North East Queensland, Australia. Habitat associations were modelled for five species based on photographic sampling in 40–80 sites per estuarine up- and downstream component: Uca seismella occurred in sites with little structure, bordered by low intertidal vegetation; Macrophthalmus japonicus occupied flat muddy sites with no structure or vegetation; Metopograpsus frontalis and Metopograpsus latifrons occupied sites covered with structure in more than 10% and 25% respectively. Finally, both Metopograpsus spp. and Metopograpsus thukuhar occupied rock walls. Habitat associations were predictable among estuaries with moderate to high sensitivity and low percentages of false positives indicating that simple, physical factors were adequate to explain the spatial distribution pattern of intertidal crabs. Results provide a necessary first step in developing generally applicable understanding of the fundamental mechanisms driving spatial niche organization of intertidal crabs within a landscape context.

강화도 남단 조간대에 도래하는 마도요류의 환경수용능력 예측

본 연구는 현재 강화도 남단 조간대의 마도요류(알락꼬리마도요 Numenius madagascariensis와 마도요 Numenius arquata) 서식지로서의 질을 평가하고자 환경수용능력(Carrying capacity)을 추정하였다. 저서무척추동물(칠게 Macrophthalmus japonicus)의 생물량 추산에 있어 토양 입도(Sediment grain size)의 공간 분포를 고려하였으며, GIS의 공간 분석 기법을 이용하였다. 추정 결과 2012년 봄철은 약 153일 동안 11,767개체가 이용할 수 있는 수준이었으며, 가을철은 약 122일 동안 16,275개체가 이용할 수 있는 수준이었다. 환경수용능력 대비 평균 도래 개체군의 차지 비율은 봄철 9.4%, 가을철 5.9%의 수준이었으며, 이는 분석 방법이 달라 직접 비교는 어려우나 1993-94년 선행 연구 대비 2.8-6.3% 수준이 감소한 수치였다. 과거에 비해 환경 수용 능력이 감소한 현재의 상황에서 향후 서식지 보전을 위한 지속적인 연구와 관리가 매우 시급하다고 판단되며, 나아가 향후 조간대의 다양한 서식지 특성을 반영한 공간 분석을 통해 더욱 정교한 예측이 필요하다. In this study we estimated the carrying capacity of the southern intertidal zone of Kanghwa Island to evaluate the habitat quality for Curlews(Far Eastern Curlew Numenius madagascariensis and Eurasian Curlew Numenius arquata). Biomass of the macroinvertebrate(Macrophthalmus japonicus) was estimated by based on the spatial distribution of the sediment grain size using GIS tools. According to our analysis the southern intertidal zone of Kanghwa Island was able to support 11,767 individuals for 153 days in the Spring 2012 and 16,275 individuals for 122 days in the Autumn 2012. The proportion of mean population to the carrying capacity in the Spring and Autumn was 9.4% and 5.9%, respectively. These values are 2.8-6.3% smaller than those of the previous study held in 1993-94. For the conservation of the study area, more research and management is needed. And in further studies, diverse characteristics of the intertidal habitat should be considered in spatial analysis to have a precise estimate of the carrying capacity.

Burrow association of Hemicyclops (Copepoda: Poecilostomatoida) as a possible strategy for predator avoidance

We examined the potential advantage of the association of Hemicyclops species with decapod burrows in their avoidance from fish predators through gut-content analysis of fishes collected from the estuary of the Tama River, Japan, and an experiment applying model burrows. The small gobiid species Pseudogobius masago, collected from an area dominated by burrows of the ocypodid crab Macrophthalmus japonicus, showed a high frequency of Hemicyclops gomsoensis in their guts relative to the other co-occurring fish species. In the experiment, no significant difference was observed in the numbers of H. gomsoensis eaten by the goby between the treatments with and without the model burrows. Another goby, Acanthogobius flavimanus, from an area dominated by burrows of the mud shrimp Upogebia major, showed very low frequencies of H. gomsoensis in their guts, as compared with those in P. masago. They had also ingested H. spinulosus and H. ctenidis, in spite of the overwhelmingly high abundance of H. gomsoen- sis in the burrows. The number of H. gomsoensis eaten by A. flavimanus was significantly lower in the treatments with the model burrows than in the absence of burrows. Since A. flavimanus was the most dominant demersal fish in the study area, H. gomsoensis seemed to avoid predation from this potentially strong predator by inhabiting the decapod burrows. H. ctenidis and H. spinulosus seemed to avoid predation by trespassers by inhabiting the smaller burrows of polychaetes, but this strategy may be less efficient against large predators that feed on polychaetes.

바지락 치패발생장 조성을 위한 모래살포가 저서동물 군집구조에 미치는 영향 - 태안군 고남면 모래톱 갯벌 사례 -

This study was conducted to investigate the impact of sand addition to an intertidal for the development of the Manila clam habitat on benthic community structure. For this, we focused on the spatio-temporal changes in the surface sediment condition and benthic community structure before and after the event. Study site was an sandbank in Gonam-myeon, Taean-gun where sand added to on July 2010. We set three stations at each of sand adding area (experimental plot) and non sand-adding area (control plot) and did sampling works ten times from June 2010 to October 2011. Directly after the event, surface sediments changed to very coarse sand, but the state was not maintained over four months because of seasonal sedimentation and finally got back to very fine sand in eight months. The number of species and density were temporarily reduced right after the event and crustacean species such as Apocorophium acutum, Photis sp. were most negatively affected by the event. However, the number of species recovered from the reduction in three months and density did in four months due to the recolonization by the existing species and species in the vicinity of the plot. During the study period, dominant species continuously changed from the species such as A. acutum, Photis sp. at the time before the event, through the species such as Heteromastus filiformis, Macrophthalmus japonicus at the time right after the event, to the species such as Musculista senhousia, Ruditapes philippinarum, Mediomastus californiensis in the latter part of the study period. Although surface sediment properties and ecological indices recovered within a certain period after the event, the recovery of community structure has never been observed up to the end of the study.

Surveys of Gynaecotyla squatarolae and Microphallus koreana (Digenea: Microphallidae) Metacercariae in Two Species of Estuarine Crabs in Western Coastal Areas, Korea

To figure out the geographical distribution of Gynaecotyla squatarolae and Microphallus koreana metacercariae in Korea, shore crabs of southwestern coastal areas were examined. Eight coastal areas in Inchon-si (A), Gyeonggi-do (B), Chungcheongnam-do (C, D, and E), Jeollabuk-do (F), and Jeollanam-do (G and H) were selected, and 2 kinds of crabs, Macrophthalmus dilatatus and/or Macrophthalmus japonicus, were caught. After transportation to the laboratory, 15 crabs per each group were grouped and ground in a mortar and pestle, and examined for microphallid metacercariae. In M. dilatatus, G. squatarolae metacercariae were recovered from 3 (C, E, and H) out of 6 regions, but M. koreana metacercariae were not recovered. In the case of M. japonicus, G. squatarolae metacercariae were recovered from 6 (B, D, E, F, G, and H) of 7 areas surveyed, and M. koreana matacercariae were detected from 5 regions (A, B, D, F, and H). These results indicate that the life cycle of G. squatarolae is maintained in the western coastal areas using M. dilatatus and M. japonicus as intermediate hosts, while that of M. koreana is maintained only using M. japonicus.

男里川河口部における土壌および微地形の違いに対するカニ類３種の分布域に関する研究

We investigated distributions of 3 species of crabs,Uca lactea, Macrophthalmus japonicus and Helice tridens, and soil conditions at random 364 plots in the mouse of the Onosato River, Osaka in September 2008. We also surveyed microtopography using a terrestrial laser scanning system in this area and made digital elevation model (DEM). Classification tree models were developed using distribution data of crabs and soil and topographic condition dataset. Deviance weighted scores (DWS) of explanatory variables at these models suggested that the most influential variables for distributions of crabs was the ratio of sediment particles which diameter under 0.250 mm. DWSs of explanatory variables at other classification tree models without using soil condition dataset were indicated that influential variables were distance to vegetation, distance to tidal flat and elevation. Prediction accuracies of distributions of crabs at later models were almost same compared to prior models. Mapping predicted suitable habitats of crabs on later models generally worked well, but had some mispredictions, because these models could not represent soil conditions adequately.

한려해상국립공원 관음포 갯벌의 대형저서동물 군집 구조

This study was performed to investigate the community structure of the macrobenthic invertebrates on the Gwaneumpo tidal flat, Hallyeohaesang National Park, Korea. Benthic invertebrates were collected between April and September 2006 at each five station. A total of 67 macrobenthic species were collected. The overall average macrobenthos density and biomass were 1,429 individuals/m² and 154.40 gWWt/m², respectively. Based on the abundance and biomass data, there were 10 dominant species accounting for approximately 86.4% of total individuals. The highest densities were found in the polychaetes Heteromastus filiformis, Ceratonereis erythraeensis, the brachyura Ilyoplax pusilla and the amphipoda Corophidae unid. On the contrary, the top ten species made up 94.2% of the total biomass while the three most abundant, the bivalve Cyclina sinensis, the brachyura Macrophthalmus japonicus and the anomura Upogebia major. The conventional multi-variate statistics(cluster analysis and non-metric multi-dimensional scaling) applied to assess spatial variation in macrobenthic assemblages. Cluster analysis and nMDS ordination analysis based on the Bray-Curtis similarity identified 2 station groups. The group 1 was associated with upper tidal flat station(station 1) and was characterized by high abundance of the polychaetes C. erythraeensis, Cirriformia tentaculata, the brachyura I. pusilla, the amphipoda Corophidae unid. and the isopoda Paranthura japonica. However, group 2 was consisted with middle and lower tidal flat station(Station 2～5) and was numerically dominated by the polychaetes Capitella capitata, Glycera chirori, the brachyura M. japonicus, the amphipoda Pleustes sp. and the anomura U. major.

The role of crabs ( Macrophthalmus japonicus) burrows on organic carbon cycle in estuarine tidal flat, Japan

The objective of this study is to elucidate the burrow structure and to clarify the role of burrows in material cycle in the tidal flat. In our work, we focused on the dominant species in muddy tidal flat, crab Macrophthalmus japonicus. Burrow structure of Macrophthalmus japonicus was investigated on a Katsuura river tidal flat in Tokushima prefecture, Japan, using in situ resin casting. Sampling was conducted in August 2006, and a total of 48 burrow casts were obtained. Burrows consisted mainly of J-shaped structures (98%) while the rest belonged to U-shaped structures (2%). The maximum measured burrow volume was 120 cm 3 and wall surface area was 224 cm 2, while maximum burrow length and depth were 23.2 cm and 16.5 cm, respectively. Burrow volume and surface area were strongly correlated with carapace width of M. japonicus. Investigation of the individual number of M. japonicus in 13 quadrats (50 × 50 × 20 cm) was conducted using 2 mm sieve. The number of M. japonicus was 15–31 ind./m 2. Using cohort analysis we estimated that surface area of burrows was 0.07–0.15 m 2/m 2. CO 2 emission rate was measured at the surface sediment during the period from June to December 2008. Results varied from 13.8 ± 2.2 to 49.4 ± 3.2 mg CO 2/m 2/h, and organic carbon decomposition was 3.8 ± 0.6–13.5 ± 0.9 mg C/m 2/h. This leads the increase of organic carbon decomposition by 1.1 times, because of the expansion of the tidal flat surface area by burrowing activity. Organic carbon decomposition in burrow walls therefore contributed to organic matter decomposition in the tidal flat. These results indicated that in situ activities of Macrophthalmus japonicus significantly influence the material cycle and it is important to consider the existence of burrow in order to understand the fluxes of materials and to evaluate the purification function of the tidal flat.

The macrobenthos in Spartina alterniflora salt marshes of the Wanggang tidal-flat, Jiangsu coast, China

On the Jiangsu coast, eastern China, Spartina alterniflora, which was introduced artificially into the region, is becoming a dominant plant species in the inter-tidal salt marshes. In order to evaluate the environmental and ecological impact of the colonization of S. alterniflora, we carried out investigations into the benthic macrofauna of the Spartina marshes of the Wanggang area, central Jiangsu coast, in 2006 and 2007. Based on analysis of the data sets obtained, 12 species of macrobenthos have been identified for the Wanggang salt marsh, including S. alterniflora, Cerithidea cingulata, Littorna scabra, Bithynia fuchsiana, Macrophthalmus japonicus, Uca arcuata, Nereis sp ., Boleophthalmus petinirostris, Cyclina sinensis, Bullacta exarata, Angustassiminea castanea and Glaucomya chinensis. The results indicate that some of the native species have adapted to the new ecological environment associated with the cordgrass S. alterniflora. The biomass of macrobenthos varies significantly over different parts of the salt marsh. Further, there is a seasonal change in bio-density, with the density in summer (July and August) > autumn (November) > early summer (May). At the landward edge and over the central part of the S. alterniflora marsh, the bio-diversity is higher than the other areas of the marsh.

Quantitative Evaluation of Bioturbation by the Burrowing Macrophthalmus japonicus

Quantitative Evaluation of Bioturbation by the Burrowing Macrophthalmus japonicus

새만금 4호 방조제 연결 후 군산갯벌 대형저서동물군집 변화

With the reduction of tidal currents by the closing of the Saemangeun 4th dyke, sedimentary environments on the Gunsan tidal flat, the nearest inner flat from the 4th dyke, has been severely changed, which might affect macrobenthic assemblages on the habitats. In order to investigate changes in macrobenthic community structure on Gunsan tidal flat, field surveys were seasonally conducted at seven stations from April 2002 to November, 2005. Sedimentary facies on the study area were shifted into muddominant facies. The fine sediment has been greatly deposited on the tidal flat with accumulation of organic materials after closing the water passage of 4th dyke section. These drastic variations in environments gave rise to change in macrobenthic community structure. Since the closure of the 4th dyke, the number of species of macrobenthos has gradually decreased. And the filter feeders and sand-favored species such as Urothoe convexa, Macrophthalmus dilatatus, Umbonium thomasi, and Mactra veneriformis have been replaced by the deposit feeders such as Macrophthalmus japonicus and Ilyoplax pingi. MDS ordination based on Bray-Curtis similarity from forth-root transformed species abundance data showed that the macrobenthic communities have passed through three succession stages from 2002 to 2005. During the third stage of 2005 opportunistic species such as Prionospio japonica, Heteromastus filiformis and Sinocorophium sinensis increased in population on the tidal flat.

Dietary contribution of the microphytobenthos to infaunal deposit feeders in an estuarine mudflat in Japan

The food sources of benthic deposit feeders were investigated at three stations in an estuarine mudflat (Idoura Lagoon, Sendai Bay, Japan) during July and August 2005, using δ13C and δ15N ratios. Sediment at the stations was characterized by low chlorophyll (chl) a content (0–1 cm depth, <4 μg cm−2) and the dominance of riverine–terrestrial materials (RTM) in the sediment organic matter (SOM) pool. Surface-deposit feeders (Macoma contabulata, Macrophthalmus japonicus, and Cyathura muromiensis) exhibited much higher δ13C values (−18.4 to −12.4‰) than did the SOM pool (<−25‰). A δ13C-based isotopic mixing model estimated that benthic diatoms comprised 45–100% (on average) of their assimilated diet, whereas RTM comprised a lesser fraction (29% maximum). The major diet of the deep-deposit feeding polychaetes Notomastus sp. and Heteromastus sp. was benthic diatoms and/or marine particulate organic matter (POM), with little RTM assimilated (39% maximum). The consumers appeared to lack specific digestive enzymes and to use detritus-derived carbon only after its transfer to the microbial biomass. The isotopic mixing model also showed that the dietary contribution of RTM increased slightly (15% maximum) in the vicinity of freshwater input, suggesting that spatial changes in RTM supply affect the dietary composition of deposit feeders. These results clearly demonstrate that deposit feeders selectively ingest and/or assimilate the more nutritious microalgal fractions in the SOM pool. Such adaptations may allow enhanced energy gain in estuarine mudflats that are rich in vascular plant detritus with low nutritive value.

전남 하의도 갯벌에 서식하는 칠게, Macrophthalmus japonicus의 연령과 성장

The ocypodid crab, Macrophthalmus japonicus, commonly occurs in tidal flats in areas around Korea. We examined the age and growth of M. japonicus collected from the tidal flats of Haui Island in Jeollanamdo, Korea, from January to December 2006. According to variation in the monthly fatness index, the population spawned from June to August. To estimate parameters of growth, frequencies of monthly carapace lengths were analyzed using FiSAT II. The allometry of females differed from that of males. VBGE(von Bertalanffy growth equation) and seasonal VBGE were determined using monthly average carapace lengths for males and females, and an equation for estimating seasonal growth was calculated using regression coefficients.

A new species of the sentinel crab Macrophthalmus (Mareotis) Barnes, 1967 (Crustacea: Brachyura: Macrophthalmidae) from Western Australia

Specimens previously identified as Macrophthalmus japonicus from Shark Bay, Western Australia, are described as a new species, M. pistrosinus. The new species differs both in behaviour and morphology from its closest relatives, particularly in characters such as proportions of male abdomens, setation patterns of claws, carapace dentition and leg morphology.

Life history of the copepod Hemicyclops gomsoensis (Poecilostomatoida, Clausidiidae) associated with decapod burrows in the Tama-River estuary, central Japan

A 17-month field survey and laboratory experiments were conducted to investigate the life cycle, seasonal population fluctuations, and salinity tolerance in the poecilostomatoid copepod Hemicyclops gomsoensis associated with the burrows of the mud shrimp Upogebia major and the ocypodid crab Macrophthalmus japonicus in the mud-flats of the Tama-River estuary, central Japan. On the basis of sample collections in the water column and from the burrows, it was revealed that H. gomsoensis is planktonic during the naupliar stages and settles on the bottom during the first copepodid stage to inhabit the burrows of U. major and, to a lesser extent, those of M. japonicus. While females carry- ing egg-sacs were present throughout the year, the copepods' reproduction took place mainly during early summer to autumn with a successive decrease from autumn to winter. Occasionally the copepod populations in the burrows suf- fered from severe flushes of river water that led to salinity decreases in the burrow water to fatal levels, but usually the salinity in the burrow was within optimal levels and permitted recovery and maintenance of the populations.

갯벌을 이용하는 풀망둑(Acanthogobius hasta)과 쉬쉬망둑(Chaeturichtys stigmatias)의 섭식생태

Food habits of the gavelin goby Acanthogobius hasta and the fine spot goby Chaeturichtys stigmatias populations were investigated in the Jangbong tidal flat near Incheon, Korea. Samples were taken monthly from November 1999 to January 2001. The gut contents of 248 gavelin gobies and 139 fine spot gobies were analyzed. The diet of the gavelin goby was dominated by the gammaridean amphipod Chitinomandibulum emargicoxa, the crabs Macrophthalmus japonicus and Ilyoplax pingi, the shrimp Exopalaemon carinicauda, the bivalve Raetellops pulchella and the macro-algae Porphyra tenera. On the other hand, the fine spot goby mainly feed on the shrimps Crangon affinis, Latreutes mucronatus, E. carinicauda and Alpheus japonicus, the gammaridean amphipods C. emargicoxa and Synchelidium miraculum, and the bivalve R. pulchella. A comparison between frequencies of occurrence and abundance of food items in the gut showed that crustaceans (gammaridean amphipods, crabs and shrimps) and bivalves were important foods for the two gobies. However, the main components of the gut contents were different between two species, though this was probably due to differences in spatial distribution patterns of gobies and their prey items. In conclusion, both the gavelin goby and the fine spot goby, despite being the related species and co-inhabiting the similar part of the tidal flat, had quite distinct food habits and low dietary overlap (Schoener`s index: 0.4). These indicated that the two gobies are or were partitioning resources in space and time for maximum uitilization of available food.

The sediment-water interface increment due to the complex burrows of macrofauna in a tidal flat

The architecture of macrofaunal burrows and the total area of the sediment-water interface created by biogenic structure were investigated in the Donggeomdo tidal flat on the west coast of Korea. Resin casting methods were applied to recover burrows of four dominant species, Macrophthalmus japonicus, Cleistostoma dilatatum, Perinereis aibuhitensis, and Periserrula leucophryna, and whole burrows within the casting area at three sites in different tidal levels.P. leucophryna excavated the largest burrow in terms of a surface area among them. In the case of whole burrow casting, the space occupied by the biogenic structure was extended into deeper and expanded more greatly at the higher tidal level. In the uppermost flat, the burrow wall surface area within sediment was more extensive than the sediment surface area. Increased oxygen supply through the extended interface could enhance the degradation rates of organic carbon and also change the pathways of degradation. Quantifying the relationship between the extended interface and mineralization rate and pathway requires more extensive study.

Genetic and behavioral diversity in the Macrophthalmus japonicus species complex (Crustacea: Brachyura: Ocypodidae)

Two morphologically similar ocypodid crabs, Macrophthalmus japonicus and M. banzai, are distributed in East Asia from Japan to China, a disjunct population of the former also having been reported from western Australia. To clarify the genetic relationships among M. japonicus and M. banzai in East Asia and M. japonicus in Australia, a phylogenetic analysis was carried out based on nucleotide sequences of the mitochondrial 12S rRNA to16S rRNA genes (628 base pairs). The resultant tree revealed three major lineages, represented by M. banzai, Japanese and Korean M. japonicus, and Australian M. japonicus. The Australian M. japonicus lineage has diverged considerably from the other two lineages, having an evolutionary distance of 0.208–0.246, whereas the sequence divergence between East Asian M. japonicus and M. banzai ranged from 0.088 to 0.105. Although the waving display of Australian M. japonicus is performed in the same manner as in Japanese M. japonicus, other social behaviors, such as fighting and mating, differ somewhat. The genetic and behavioral differences strongly suggest that Australian M. japonicus is a distinct species, separate from East Asian M. japonicus. Among three M. banzai populations investigated, substantial genetic differentiation was observed, with Korean M. banzai being more divergent from two Japanese populations. Differences in waving display and some morphological characters also separate Korean M. banzai from Japanese M. banzai. Although the genetic divergence among these populations was at a level similar to those observed among other intraspecific crustacean populations, the overall differences suggest that Korean and Japanese M. banzai represent a complex of two species or subspecies.

A new species of Hemicyclops (Copepoda, Poecilostomatoida) from burrows of the ocypodid crab Macrophthalmus japonicus in an estuarine mud-flat in Tokyo Bay, Japan

A new species of poecilostomatoid copepod, Hemicyclops spinulosus, is described from burrows of the ocypodid crab Macrophthalmus japonicus in an estuarine mud-flat in Tokyo Bay. The new species can be distinguished from its congeners by a combination of the segmentation and setation of first antenna, the ornamentation of maxilliped and the modified seta on the first segment of the endopod of legs 1–4.

Factors affecting distribution and abundance of small demersal fishes in the Gulf of Carpentaria, Australia

The distribution and abundance of small demersal fishes at depths of 7 to 63 m in the Gulf of Carpentaria were surveyed at 103 stations in 1990 and 60 stations in 1991 with the aid of a Church dredge. A total of 234 species from 70 families was recorded. The most abundant fish groups were cryptic or benthic species such as pleuronectiforms, scorpaenids, apogonids, platycephalids, monacanthids and gobiids. Several species, such as Elates ransonnetti, Pseudorhombus elevatus and Suggrundus macracanthus, are widely distributed; others had a narrower distribution. Apogon poecilopterus, Apogon fasciatus, Arnoglossus waitei and Uranoscopus cognatus were most abundant in the northern Gulf of Carpentaria and Cynoglossus macrophthalmus, Dactyloptena papilio and Paramonacanthus japonicus in the eastern gulf. The dredge is more efficient at catching smaller fish: the smallest individuals of 113 species were caught by the dredge and a further 32 small species were caught only by the dredge. The effects of depth, substratum type and turbidity on the abundance of 17 common species at different stations are described. Neither temperature nor salinity showed significant correlations with catches of the common species. There were significant correlations between the presence of structured benthos and both the number of fish species and the number of fish individuals. The relationship between benthic structure and fish is discussed in relation to the possible effects of trawling, and it is postulated that changes to structure resulting from trawling may affect fish community composition.