The reproductive biology of the baby clam, Marcia opima, from two geographically separated areas of India

A study of the reproductive cycle of the baby clam, Marcia opima (Gmelin) was conducted at two sites along the southeast (Tuticorin Bay) and southwest (Ashtamudi estuary) coast of India from December 1998 to January 2000. Histological evidence showed that baby clam from both the sites showed two spawning seasons. First spawning season was recorded from May to July in the southeast coast. In the southwest coast, the first spawning season was observed through March to May. A second spawning season from September to December was recorded in both the coasts. In the southeast coast, minimum and maximum condition indices were obtained in January 2000 and April 1999 respectively and decreased from May to June and November to January, signifying the two spawning periods. Most of the animals were either in spent or indeterminate gonadal stage from May to August and November to January indicating the active spawning during that months in the southeast coast.     

Reproductive performance and offspring quality of Chinese mitten crab Eriocheir sinensis (H. Milne-Edwards) females fed an optimized formulated diet and the razor clam Sinonovacula constricta

After feeding female Eriocheir sinensis on an optimized formulated diet or fresh razor clam Sinonovacula constricta for 7 months, their reproductive performance and offspring quality were compared. To evaluate diet nutrient contents, the proximate, fatty acid and amino acid compositions of the formulated diet and the razor clam were analysed. The nutritional value of the diets was determined by assessing survival, gonadosomatic index (GSI) and hepatosomatic index (HSI) of female crabs from both diet treatments, together with the percentage of females that spawned, total egg production per female and fecundity (number of eggs g^?1 female wet weight). Furthermore, the quality of eggs and newly hatched larvae from the two dietary treatments were determined using the following parameters: egg diameter, wet weight and dry weight, hatchability, proximate and fatty acid profile of eggs, larval carapace length, resistant to starvation and osmotic shock, larval survival and development to the zoea II stage. Higher protein, phospholipids (PL) and amino acids (AA) contents were found in the razor clam while the formulated diet contains higher levels of ash, total lipid (TL) and 18:1n‐9, 18:2n‐6 and 22:6n‐3 fatty acids. Although female crabs fed the two different diets showed similar reproductive performances, newly hatched zoea I larvae produced by the crabs fed the formulated diet had significantly longer mean carapace length and shorter development time to the zoea II stage under identical culture condition (P<0.05). Moreover, dietary fatty acid appeared to have more significant effects on the fatty acid composition of the hepatopancreas than it did on mature ovaries or eggs. This suggests that the fatty acid profile of mature ovaries is indicative of the specific fatty acid required for ovarian development in E. sinensis. In conclusion, our results show that the optimized formulated diet developed in this laboratory can totally replace the razor clam, a broodstock food widely used in E. sinensis hatcheries in China. This encouraging result should facilitate more reliable hatchery production of this important aquaculture species.     

Amino Acid Profiles of Bivalve Mollusks from Beibu Gulf,China

Three bivalve mollusks—clam (Meretrix meretrix), oyster (Crassostrea rivularis), and paphia (Paphia papilionacea) from the Beibu Gulf, China—were analyzed for amino acid profile. Essential amino acids were used for nutritional quality evaluation, and free amino acids were used for taste impact evaluation. The amino acid compositions of the mollusks were quite similar; however, the contents of glycine, alanine, and tryptophan were different. Tryptophan seemed to be the limiting amino acid in clam and paphia meat protein. Oyster, on the other hand, seemed to be a source of high quality protein with well-balanced composition in essential amino acid. Glutamic acid, alanine, glycine, and arginine were the major taste-active amino acids found in the mollusks. According to the taste activity values of free amino acids, paphia was assumed to be the best savory food, followed by clam and oyster.     

Condition index and air survival time to compare three kinds of Manila clam Tapes philippinarum (Adams & Reeve) farming systems

The effects of maintaining the burrowing Manila clam in suspended culture in the sea on flesh weight changes or on condition are not yet known. This work analyses these effects using the condition index and the air survival time of clams. Samples of clams submitted to three different treatments (traditional farming on the lagoon bottom, lagoon suspended culture and open sea suspended culture) were investigated between July and November. The most sensitive of the eight condition indices for comparing the three different breeding systems was AFDW/SV. From the Tukey test (two-way ANOVA), AFDW/SV, exhibited the highest number of significantly different (P < 0.05) cases in a comparison between the month/treatment interactions. This index showed the highest values in lagoon suspension, whereas there was not much difference between bottom farming and sea suspension until after a four-month period: in November the suspended individuals recovered condition, whereas a fall was recorded in the traditional farming area. As regards air survival time, individuals in sediment were more resistant, except in November, when lagoon suspended ones were hardier. Suspended culture, which is necessary for hygiene and health reasons to market the product, is an advantageous necessity for farmers in both lagoon and sea, especially over periods of several months.     

Hard clam relocation as a potential strategy for QPX disease mitigation within an enzootic estuary

Monitoring of persistent QPX infections in clams of Raritan Bay (New York) shows certain areas of the estuary have remained without any significant disease prevalence. This study was conducted to investigate the potential to mitigate QPX disease by relocating infected hard clams, Mercenaria mercenaria (Linnaeus), from enzootic areas to nearby sites with prevailing environmental conditions suggested to deter infection and favour remission and healing. Clams were collected from a location with consistent disease prevalence in central Raritan Bay and brought to near shore habitats subject to lower salinities and higher summer temperatures. A reduced host density treatment was included in the study to examine the common observation of high clam density in the most persistently infected locales. An additional treatment retained clams above the sediment, since sediments are suspected to represent a QPX reservoir. At the end of the 4‐month study all treatments displayed less QPX disease than the control group and the greatest contrast was provided by the disappearance of infections in a tidal creek.     

Reproductive biology of Venus clam Gafrarium tumidum (Roding, 1798) from Southeast coast of India

The reproductive biology of tumid venus clam Gafrarium tumidum (Roding) was studied in detail from the Southeast coast of India. Sample size ranged from 10.3 to 41.3 mm. Sexes are separate but not differentiated externally. Annual sex ratio male:female (M:F) deviated significantly from the 1:1 ratio with females dominating. Based on ova diameter progression of gonad smear and histology, four and two maturity stages of gonads were differentiated in female and male clams, respectively. Peak spawning was observed during November and a minor one in April. The monthly average condition index based on wet/dry flesh weight ranged from 7.24 (November) and 14.14 (September) and 8.82 (October) and 14.38 (August), respectively. The condition index observed by both the methods is comparable and corresponds with the spawning season. Water content observed for male and female clams varied negligibly and showed positive correlation with spawning period. Size at first maturity was estimated to be 22.3 mm.     

Marine microalgae as dietary supplements in the culture of juvenile Chinese horseshoe crabs,Tachypleus tridentatus (Xiphosura)

Five treatments (short‐neck clam Ruditapes philippinarum and four formulated diets with the green microalgae Dunaliella tertiolecta or the golden‐brown microalgae Isochrysis galbana in the ratio (dw/dw) of 5% or 10% to that of clam meat) were used to investigate the growth performance and haemolymph quality of juvenile Chinese horseshoe crabs Tachypleus tridentatus under laboratory culture. At the end of the 12‐week study, various growth and moulting indicators as well as haemolymph biochemical parameters did not show any significant differences among the treatments. Significantly higher percentages of haemolymph amoebocyte viability and granular‐spherical amoebocyte state were noted in both 5% and 10% I. galbana‐supplemented diets compared to that of clam meat. However, the percentages of these two haemolymph parameters in juveniles fed with D. tertiolecta decreased significantly at the end of the experiment. Such differences were attributed to the presence of polyunsaturated fatty acid (PUFA), notably eicosapentaenoic acid (EPA), in I. galbana that was absent in D. tertiolecta and clam meat. Like many marine invertebrates, juvenile horseshoe crabs do not naturally obtain sufficient PUFAs from their diets to meet developmental and physiological needs; hence, supplementing microalgae with high levels of EPA in a protein‐rich diet boosts immune competence and the health status of juvenile horseshoe crabs while under culture.     

Shell shape and meat condition in selectively bred Sydney rock oysters,Saccostrea glomerata (Gould, 1850): The influence of grow‐out methods

The Australian edible oyster industry has been severely impacted by disease and declining yields since the 1970s. Selective breeding of Saccostrea glomerata is one measure addressing these problems by producing fast‐growing, disease‐resistant oysters. Farmers report that selected oysters have different growth characteristics than their wild counterparts using conventional grow‐out methods. This study investigated how different grow‐out methods influence commercially valuable oyster characteristics including shell length, shape, surface growth deformities and meat condition. In June 2015, selectively bred S. glomerata spat were deployed in two estuaries (Hawkesbury River and Georges River) in NSW, Australia, using three grow‐out methods (fixed trays, Stanway cylinders and floating baskets). In November 2015, oysters were transferred among grow‐out methods to test for the effects of changing grow‐out methods on oyster growth patterns. Oysters transferred from baskets to cylinders and from trays to cylinders had, on average, deeper and wider shells, a higher meat condition and fewer shell surface deformities than oysters in other grow‐out method combinations. However, these oysters were smaller than oysters not grown in cylinders. While there were some differences in growth patterns between the estuaries, overall it was the grow‐out methods that most influenced oyster characteristics. This was attributed to differences in the amount and magnitude of movement oysters experienced in the grow‐out methods, as recorded by motion sensors. This study demonstrates how grow‐out methods can be managed to achieve desired growth trajectories and therefore improve marketability among selective bred S. glomerata.     

Effects of environmental factors and food availability in Northern Aegean sea on the cultivation of Mediterranean Mussels (Mytilus galloprovincialis)

This study used two different collectors made of polypropylene (PP) rope and polyethylene (PE) fishing net to determine Mediterranean mussel's settlement, growth, condition index (CI), meat yield (MY) and shell thickness index (STI) during the period spent between June 2017 and November 2018. With this regard, chlorophyll a, water temperature, salinity, pH and particulate matter were defined through water samples that were collected on monthly basis triplicate. The mean chlorophyll a level was recorded as 0.32 ± 0.31 μg/L, while water temperature was 19.73 ± 5.14°C, salinity was 35 ± 2.070‰, pH was 8.12 ± 0.04, and TPM was 14.91 ± 10.48 mg/L. As a result of the cultivation period of 8 months spent following the first intense grip, the length of the mussels is measured as 31.79 ± 6.20 mm. Based on the Pearson correlation analysis results, the most important environmental parameter affecting Mediterranean mussels growth in length on PP rope collectors is the temperature (p < .05). The STI and CI were determined to be related with environmental temperature parameters, while no determinations could be obtained concerning the correlation of MY with environmental parameters. Assessment of Mediterranean mussels’ growth rate in PP rope collectors proved significant differences (p < .05) between March and November 2018. As no Mediterranean mussels are observed on PE fishing nets during the samplings performed throughout the study period, it is determined that PE fishing nets are not suitable collector types for Mediterranean mussel cultivation.     

Monthly variation of biochemical composition of Pacific oysters Crassostrea gigas from two main cultivation areas in Japan

Pacific oysters were harvested from November to March at Miyazaki and Miyagi in Japan. From biometric analysis, the condition indices (CI^CG; high CI^CG indicates large oyster meat) of oysters were high in February and March at Miyazaki whereas CI^CG at Miyagi showed high values in December and February. Lipid content in oysters at Miyagi harvested in February was the highest. Glycogen content was high in oysters harvested in February from both cultivation areas. In November, the calcium content in oysters harvested at Miyazaki was the highest. Taurine was the predominant free amino acid in oysters, at concentrations of 2180–3230 mg/100 g dry sample. Glutamate was the predominant component of total amino acid in oysters, at concentrations of 4530–6000 mg/100 g. The percentage of eicosapentaenoic acid (EPA) in total lipid of oysters did not show significant differences between harvesting months. Based on all analyses, oysters from Miyazaki showed good quality in March with high CI^CG, glycogen, and lipid contents, whereas oysters from Miyagi showed good quality in February. These analysis data including not only condition indices but also biochemical composition might be useful parameters allowing establishment of evaluation criteria.     

Seasonal Changes in Quality and Fatty Acid Composition of Black Mussel (Mytilus galloprovincialis)

The study was designed to assess the seasonal variations in the quality and lipid profile of mussel meat (Mytilus galloprovincialis) harvested along the Bulgarian coast of the Black Sea. The trial period lasted from June to October, and the sampling was carried out in the area of Varna Bay. Technological quality of the mussels was determined by measuring the water holding capacity (WHC) and cooking and roasting losses. Proximate composition, total aerobic plate count, and fatty acid analysis were carried out. Technological parameters and nutritional quality of the mussel meat were strongly affected by the season. During the summer, the mussels had higher mass, meat content, and meat yield (p < 0.001) compared to the early autumn, which corresponds to the lowest protein content during this season. Lipid profile showed seasonal variations in both individual and total fatty acid amounts (p < 0.001). Saturated fatty acids (SFA) had the highest content in summer, while monounsaturated fatty acids (MUFA) decreased gradually until the autumn. The content of polyunsaturated fatty acids (PUFA) reached its peak in October, contributing to the most favorable values of the nutritional indices of lipids in the early autumn.     

Physical properties of soft shell clams, Mya arenaria

Soft shell clams, Mya arenaria, are found from Canada to North Carolina on the U.S. Atlantic Coast and from Canada to California on the U.S. West Coast. They are also found in several other parts of the world including Europe. The primary market for these clams on the U.S. East Coast is in New England. Clams are sold whole live or in one of the several cooked forms. Commercial soft clam shucking and processing is primarily by manual methods. However, physical properties data for these clams is lacking and is a constraint on the automation of processing. Several properties of soft shell clams harvested from five different harvest locations in the Chesapeake Bay are detailed in this paper and relationships between the components of the clam are defined mathematically through regression equations. The live weight and the clam length are related to shell weight, siphon weight, meat weight, total solids and free water in the clams. Meat yields under both standard processing methods and for clams steamed and consumed with only the shell removed are detailed. The effect of harvest area on the clam parts is also defined. Soft shell clams shucked manually result in a meat yield of approximately 29% of the live weight. If steamed and eaten the meat yield may be as high as 43% of the live weight, primarily because the siphon is often consumed in steamed clams.     

Allometry and condition index in green mussel Perna viridis (L.) from St Mary's Island off Malpe,near Udupi,India

The morphometry, length–weight and condition index of green mussel P. viridis (L.) from St Mary's Island, off Malpe, near Udupi, were examined from December 2004 to December 2005. The calculated regression equations between length and breadth and length and width for the entire study period were L=0.5071+ 0.3921B and L=0.0179 + 0.3225W respectively. The monthly b values of length–breadth and length–width relationships varied from 0.3636 (March 2005) to 0.4374 (December 2004) and from 0.3022 (December 2005) to 0.3466 (August 2005) respectively. The data on length–total weight (W=0.0986L^2.9495), length–wet tissue weight (W=0.031L^2.7173), length–dry weight (W=0.005L^2.9337) and length–shell weight (W=0.0351L^3.061) showed a nonlinear pattern. The coefficient of allometry (b) values ranged from 2.7949 (April 2005) to 3.0999 (September 2005) for length–total weight relationship and from 1.5203 (August 2005) to 3.328 (March 2005) for length–dry weight relationship. The monthly mean values of the condition index varied from 5.17 (December 2004) to 7.76 (November 2005). The variation in condition index followed the breeding period and seasons. The maximum condition index (22–24) was recoded in May 2005. Based on the data on condition, it is suggested that the ideal period for commercial exploitation of Perna viridis from the Island is from March to August, when the meat yield is the highest. The hierarchical cluster analysis using complete linkage showed three major groups of biological parameters of mussels. The PCA showed a total of five components, which together accounted for 89.31% of total variance. The first component accounted for 44.08% of variance, followed by second component for 18.02% and the third component for 11.66% of variance. The remaining fourth and fifth components together accounted for 15.55% of variance.     

Effect of dried algae diets on conditioning and fecundity of Manila clam, Tapes philippinarum (Adams and Reeve)

Abstract The effectiveness of live-algae replacement diets for the conditioning and spawning success of adult Manila clam, Tapes philippinarum (Adams and Reeve), was assessed. Two dried diets were tested: a diet of dried Tetrasetmis suecica (Kylin) Butch, and a mixed diet of dried T. suecica (70%) and dried Cyclotella cryptica Reimann et al. (30%). These diets were compared with three live diets: Skeletonema costatum (Grev.) Cleve, Dunaliella tertiolecta (Butcher) and T. suecica. An unfed group was used as a control. The same ration (dry weight) of food was supplied for all groups at 6% of the dry meat weight per day. The broodstock were conditioned for 7 weeks. After 4 weeks none of the animals was ready to spawn. After 6 weeks all the diets promoted spawning and after 7 weeks the unfed group also spawned. It seems that dried algal diets are effective for conditioning and spawning of Manila clams, as the dry meat weight, condition index and fecundity of broodstock fed these diets were significantly greater than for unfed animals. However, the fecundity and proportion of parental lipid released in the eggs of clams conditioned with dried diets was lower than for the clams conditioned with live algae.     

基于生计渔业调查的黄河口西南侧潮间带渔业生物多样性及其季节变化

基于2020年黄河口须子网生计渔业和生物组成周年监测数据,开展黄河口潮间带渔业生物多样性及其季节变化研究,评价须子网生产对黄河口渔业资源补充的影响。结果显示,黄河口潮间带的渔业生物种类丰富,共鉴定记录61种生物,以鱼类和甲壳类居多。生物多样性和优势种组成均具有明显的月变化。多样性水平以夏季7―8月较高,秋季10―11月较低;5―9月、10―11月组群分别具有较高的种类组成相似度。各类群的数量组成中,4―7月螺类数量居多,8月螺类和鱼类数量居多,9月鱼类数量居多,10―11月蟹类数量居多。鱼类是各调查月渔获的优势类群,其中,花鲈(Lateolabrax maculatus)和 (Liza haematocheila)为各调查月都出现的优势种。个体大小–频数百分比分布显示,黄河口潮间带是小型渔业生物以及多种幼鱼分布的重要区域。4―9月,渔获物的主体均由个体重量< 2 g的生物组成(44%~82%),鱼类以个体质量< 20 g为主,优势种类组成月更替明显。研究表明,开展须子网生计渔业调查和监测是采集黄河口沿岸咸、淡水交汇区潮间带包括鱼类补充群体在内的诸多渔业生物分布资料的有效途径。研究还表明,须子网渔业生产虽为黄河口沿岸当地传统的生计渔业,但其低选择性及在迁移通道的布设方式等易对渔业资源自然补充和增殖养护群体造成破坏,建议主管部门根据幼鱼种类组成和出现季节特征,重点在夏季和初秋季对该渔业的网目和布设区域进行相应管控。     

珠江口水域鱼虾类重金属残留的调查

于 2 0 0 0年 5～ 6月、10～ 11月对珠江口区 4个入海口 (虎门、蕉门、横门和磨刀门 )进行取样调查 ,10个采样点共采得鱼虾类样品 2 4种 ,分属 2 1科。进行Cu、Zn、Pb、Cd、Ni、As、Cr的肌肉残留分析 ,并与 1986年和 1999年调查结果进行比较。结果表明 ,2 0 0 0年珠江口生物体主要残留物为As、Cd、Pb ,其污染负荷比分别为 36 .8%、2 5 .6 %和 19.8% ;Cu和Cd检出率最高 ,皆为 10 0 % ;As、Cd超标率最高 ,分别为 2 3.2 %和 16 .9%。方差分析显示 ,丰水期 (5～ 6月 )与枯水期 (10～ 11月 )Zn、As、Cr、Ni的平均残留量差异显著 ;对于不同生活水层和不同食性的鱼类 ,Cu的平均残留量差异极显著 ,呈底层 >中下层 >中上层 ,而其他 6种元素无显著差异。鱼、虾肌肉重金属污染综合指数均值为 0 .4 3,属轻度污染     

Accumulation flux of nitrogen in mudflats and its implications for benthic shellfish culture

In order to evaluate impacts of benthic shellfish culture on sediments in the Daguhe Estuary, surface sediments are sampled in February, May, August and November 2009 and the water content and nitrogen content of sediment, accumulation flux of nitrogen are studied. About 40 % of the mudflat in the estuary is used for bottom sowing culture for Manila clam Ruditapes philippinarum. The seeding density is 1.1–1.5 kg m^?2 in the estuary if the mean weight of juvenile clam is 0.3–0.5 g. Moreover, the stock density of cultivated clam that can be harvested (with mean weight 8 g) is 450–1,600 individual m^?2, and the annual yield of this species of clam is about 3.4 kg m^?2. There is significant spatial difference of water content of sediment from February to November, during which the water content in the uncultured mudflat, the cultured mudflat and the river way is 32.07, 43.95 and 37.69 %, respectively. There is no significant spatial difference of TN (total nitrogen) content of sediment, and the TN content in the cultured mudflat, the uncultured mudflat and the river way is 0.26, 0.22 and 0.29 mg g^?1, respectively. Moreover, the IN (inorganic nitrogen) content of sediment in the cultured mudflat, the uncultured mudflat and the river way is 0.09, 0.08 and 0.14 mg g^?1, which implies that there is no significant spatial difference of IN content. Furthermore, there is no significant spatial difference of EN (exchangeable nitrogen) content of sediment from February to November, during which the EN content in the uncultured mudflat or the river way is about 0.04 μg g^?1 and it is 0.03 μg g^?1 in the cultured mudflat. Thus, the benthic shellfish culture may increase the water content and there is no significant effect of benthic shellfish culture on nitrogen content. The accumulation flux of TN in the cultured mudflat, the uncultured mudflat and the river way is 0.94, 1.13 and 1.40 mg cm^?2 year^?1. The accumulation flux of IN in the cultured mudflat, the uncultured mudflat and the river way is 0.31, 0.39 and 0.66 mg cm^?2 year^?1. Moreover, the accumulation flux of EN in the uncultured mudflat and the river way is nearly equal, which is 0.21 and 0.20 μg cm^?2 year^?1, respectively. The accumulation flux of EN in the cultured mudflat is 0.10 μg cm^?2 year^?1. Thus, the benthic shellfish culture in the estuary does not enhance the accumulation of TN or IN. Nevertheless, it may reduce the accumulation of EN. Furthermore, it is cautious to evaluate the effect of benthic shellfish culture on sediments by the nitrogen content only. The accumulation flux of nitrogen may be one better index to evaluate the impact.     

Meat Yield,Condition Index,and Biochemical Composition of Mussels (Mytilus galloprovincialis Lamarck, 1819) in Sinop,South of the Black Sea

Monthly variations in meat yield and biochemical composition of Mediterranean mussels on lantern nets were investigated from May 2005 to May 2006, in Sinop, south of the Black Sea. Dry weight condition index was between 2.66 and 7.10% with a mean of 4.86 ± 0.36%. Meat yield was maximum (26.69%) in March and minimum (17.43%) in October. Moisture values were between 78% (in June) and 86% (in April). Protein content in dry weight of mussels reached the highest value in February (74.64%) before the spawning time. Lipid value was maximum (18.03%) in May 2005.     

Autumn conditioning of the oyster Crassostrea gigas: a new approach

Gametogenesis, emitted gametes and larval yield (D larvae) of the oyster, Crassostrea gigas (Thunberg), were simultaneously examined in laboratory under two different conditions of temperature and photoperiod. One batch (“natural” cycle, NC) followed the equivalent cycle of average conditions of these parameters measured in La Tremblade (Charente-Maritime, France) during the last 15 years. The second batch (“accelerated” cycle, AC) was maintained under a variation two times faster of these parameters. Three conditioning experiences were performed during October, November and December 1998 with oysters from both NC and AC conditions. “Accelerated individuals” produced oocytes in growing stage from October and mature oocytes were noticed from December. In contrast, oysters from NC produced growing oocytes until January. Animals in AC produced 42% (October), 56% (November) and 96% (December) of mature oocytes after conditioning. Only the “natural” lot conditioned in December showed growing (23%) and mature oocytes (8%). Higher Walne–Mann index (WMI) values were recorded for “accelerated oysters” and significant differences (P<0.05) between treatments were noticed during October and November, suggesting nutrient accumulation before conditioning in the “accelerated” condition. Gamete emission and D larval yield results were equivalent to those reported in literature during early spring for the same species. The effect of temperature and photoperiod is discussed in order to understand their relationship with gametogenesis under these particular experimental conditions. It was demonstrated that internal clocks regulating gametogenesis can be change if stimulating factors (environmental cues) also change.     

珠江口大型底栖动物数量与生物多样性的分布特征

为了更好地了解河口生物多样性的演变规律及退化机制,根据2015年1—12月珠江口大型底栖动物调查资料对珠江口大型底栖动物现存量和生物多样性的分布特征进行了研究。结果表明,11次采样(受台风影响7月珠江口未采集到大型底栖动物)共获取大型底栖动物67种,其中环节动物多毛纲27种,节肢动物24种,软体动物12种,其它类群4种,主要是底栖鱼类、刺胞动物和纽形动物。2015年珠江口各站位大型底栖动物丰度的变化范围在8~1192个·m^-2之间,珠江口大型底栖动物丰度的高值出现在6月和9月的崖门(分别为1192个·m^-2和1048个·m^-2)以及9月的虎跳门(1048个·m^-2),日本大螯蜚(Grandidierella japonica)、中华拟亮钩虾(Paraphotis sinensis)、凸壳肌蛤(Musculus senhousei)和彩虹明樱蛤(Moerella iribescens)丰度较高。大型底栖动物生物量变化范围在0.02~42.50g·m^-2之间,生物量的高值出现在9月的崖门、5月的鸡啼门、2—3月的磨刀门及4月的蕉门,上述站位的生物量均大于30.00g·m^-2,缢蛏(Sinonovacula constricta)、光滑河篮蛤(Potamocorbula laevis)、黑龙江河篮蛤(P.amurensis)、凸壳肌蛤和日本大螯蜚生物量较高。珠江口大型底栖动物香浓威纳指数高值出现在3月鸡啼门,为2.46;低值出现在10月磨刀门,为0.21。香浓威纳指数均值在1.11~1.81之间。鸡啼门和虎跳门大型底栖动物香浓威纳指数值月际变化较稳定。运用ABC曲线对珠江口大型底栖动物扰动状况进行评价,结果表明,1月珠江口大型底栖动物受到中等程度扰动,2—4月大型底栖动物群落有受到中等程度干扰的趋势。