Autotomy and Regeneration of Appendages in Crustaceans:A Review

Autotomy of appendages is a self-protection mechanism in crustaceans,which is defined as the reflexive loss of a limb in response to predation,competition,or other environmental factors.Single-limb injuries were the most common among the species surveyed in the present study,and the chelicerae were the most frequently lost appendages.After autotomy,hormones and signaling pathways are altered.Loss of limbs can affect foraging efficiency,although cheliped loss may be compensated by shifting to alternative prey or using both motor and oral appendages.In heterogeneous species,the loss of the major chelae may affect the selectivity of feeding.Autotomy can affect crustacean growth by reducing size increases at molting and altering the timing of ecdysis.In commercial production,removing chelicerae is an effective strategy to reduce cannibalism,and production of soft-shell crabs can be increased via autotomy.After autotomy,a new limb will regrow through regeneration and molting.This process involves the regulation of hormones,regrowth of nerves,and a number of signaling pathways that include the Wnt/β-catenin signaling pathway and transforming growth factorβsignaling pathway.Crustaceans are somewhat different from vertebrates in terms of regeneration.This review provides theoretical guidance about autotomy and regeneration applied in artificial aquaculture,and we offer several suggestions for future research on autotomy and regeneration in crustaceans.

Evolution of sex determination in crustaceans

Sex determination(SD)involves mechanisms that determine whether an individual will develop into a male,female,or in rare cases,hermaphrodite.Crustaceans harbor extremely diverse SD systems,including hermaphroditism,environmental sex determination(ESD),genetic sex determination(GSD),and cytoplasmic sex determination(e.g.,Wolbachia controlled SD systems).Such diversity lays the groundwork for researching the evolution of SD in crustaceans,i.e.,transitions among different SD systems.However,most previous research has focused on understanding the mechanism of SD within a sin-gle lineage or species,overlooking the transition across different SD systems.To help bridge this gap,we summarize the understanding of SD in various clades of crustaceans,and discuss how different SD systems might evolve from one another.Furthermore,we review the genetic basis for transitions between different SD systems(i.e.,Dmrt genes)and propose the microcrustacean Daphnia(clade Branchiopoda)as a model to study the transition from ESD to GSD.

Diel vertical migration of dominant planktonic crustaceans in the south branch of Yangtze Estuary,China

Zooplanktons are important food organisms of fishes,and their spatial and temporal distribution pattern has an important influence on the growth and reproduction of fishes in local habitats.The Yangtze River Estuary of China is rich in fishery resources,but the knowledge on the distribution pattern of zooplankton in this area is still very limited.The diel vertical migration(DVM)patterns and seasonal variations of the crustacean community,and their relationship with environmental factors were investigated in the south branch of the Yangtze Estuary,from June 2017 to May 2018.The results showed that the dispersion patterns of dominant crustacean taxa in the Yangtze Estuary were mostly aggregated.Migration amplitudes of crustacean were greater in spring and summer than in autumn and winter,and different migratory patterns occurred in different seasons.Sinocalanus dorrii,Schmackeria inopinus,Mesmackeria leuckarti,Bosmina longirostris,and B.fatalis,unlike S.forbesi,showed a significant DVM.The DVM patterns of crustaceans was possibly influenced by light dentisy,temperature,and total dissolved solids in the water column,and the fish predation effect;whereas,the nutrient concentration and pH were not supposed to be key factors.

Effects of latitude gradient and seasonal variation on the community structure and biodiversity of commercially important crustaceans in the Yellow Sea and the northern East China Sea

To evaluate the spatio-temporal variations in the community structure and biodiversity of commercially important crustaceans in the Yellow Sea and the northern East China Sea(NECS),the seasonal and regional changes in species composition,biomass structure,biodiversity and distribution of commercially important species were analyzed using bottom trawl survey data during 2014-2015.The results showed that the latitudinal gradient was obvious in species richness,dominant species and biodiversity.The indices of biodiversity increased with the decreasing latitude.When the sampling sites shifted south by one latitudinal degree,Margalefs richness index(D),Pielou's evenness index(J')and Shannon-Wiener diversity index(H')increased by 0.10.0.03 and 0.09,respectively.The biomass proportion of the cold-temperate species represented by Crangon affinis declined with the decreasing latitude,and the warm-temperate species represented by Ovalipes punctatus and Portunus trituberculatus in creased.Because of the growth regulatio n of crustaceans and the fishing moratorium,the biomass of commercially important crustaceans in the Yellow Sea and NECS was highest in October and August,respectively.Salinity had a more significant influence on H'of commercially important crustaceans than other environmental factors(including zooplankton density,sea bottom temperature and water depth).Overall,the results of this study contribute to a better understanding of community dynamics of crustaceans in the Yellow Sea and NECS,and provide evidence to verify the latitudinal gradient theory in biodiversity.

Overview and Graph Theory of the Immune System of Crustacean

In this paper,different kinds of enzymes,immune factors and regulatory factors of the immune system of crustaceans are summarized and then combed systematically and thoroughly. According to the mutual influence and effects of these factors,different symbolic forms are introduced to express the effects,and ultimately the whole node graph of the system is obtained. The graph theory can be used for further researches on the immune system of crustacean.

A Review of Various Sources of Chitin and Chitosan in Nature

Chitin was first discovered by its name from the Greek word“chiton”,which means“mail coat”.It is indeed a polysaccharide made up of naturally occurring acetyl-D-glucosamine monomers.Hatchett was the first researcher who extracted chitin from the shells of mollusks(crabs and lobsters),prawns,and crayfish in 1799.Later in 1811,Henri Braconnot discovered chitin in the cell walls of mushrooms and called it“fungine”.Chitin and chitosan are abundant in the biosphere as essential components of many organisms’exoskeletons and as by-products of the global seafood industry.The biopolymer must be deacetylated before chitosan can be produced.It can also be extracted using microbes in a biological extraction procedure.The development of products that take advantage of the bioactivities of the existing primary commercial source of chitin(crustacean)has lagged expectations.Also,the disadvantages of the present commercial source such as seasonality and competition for other uses among others has been one of the driving forces towards seeking alternative sources of chitin and chitosan in nature.This review highlights some of the efforts made by environmental scholars to locate possible commercial sources of chitin and chitosan in nature over time.

On the influence of season and salinity on the phenology of invertebrates in Australian saline lakes, with special reference to those of the Paroo in the semiarid inland

While the fauna of Australian salt lakes is now well-known, seasonal phenological patterns of invertebrates are not. Two studies on saline lakes in southern Australia suggest the lakes fill in early winter and remain at salinities characteristic for each lake during winter-spring before elevating and drying in summer. The fauna is dominated by crustaceans with few insects and all component species are present most of the time and randomly fluctuating in numbers. Lakes in the southern inland(mainly Lake Eyre) fill in summer, change little in salinity until near drying, and are dominated by crustaceans but have some insects. By contrast temporary salinas in the central inland fill episodically mainly in summer and then their salinity increases steadily as they dry without further rain. Their fauna is also dominated by crustaceans, but with a significant insect component and composition varies though the hydrological cycle. This study reports on an unusual winter fill in two central Paroo lakes and two pools, in which the crustacean fauna is similar to that in summer but insects are delayed till late spring and are not as common as in summer fills. It seems therefore that while insects are more restricted by medium and high salinities than crustaceans, they are also more restricted by cooler temperatures than crustaceans.

Genetic Determination and Exogenous Influence in Sex Differentiation in Crustacean

The mechanisms of sex determination and the influence of exogenous factors on sex differentiation in crustacean were reviewed in the paper.Most of crustecea have not obviously sex chromosome.Androgenic gland was reported as the most important sex differentiation factors,implanting or cuting AG can change the sexal characterization of larval in crustacean.Although sex differentiation of crustacean is determined by gene,it is affected by exogenous factors such as parasite,photoperiod,temperature or hormone.Most cultured species have different body weight and length between male and female,this can be used in aquaculture to produce all male or female crusteceans to improve the production.

A Method and a Surface Treatment Agent for Preventing Biofouling on Surfaces under Water

This paper presents an environm centally friendly method of inhibiting biofouling especially acorn barnacles on surfaces under water by using nicotine and selenium in the form of Se（0）, or such a substance which can be converted into them. Both of the substances are necessary to oxygen dependent organisms and will be used after conversion, but are toxic in high doses. By adding the substances to paint or other surface treatment agent which marine surfaces are treated with, organisms which are trying to establish themselves on the surfaces will be exposed to so high doses, the reactions which the settling is based on are disturbed. When the substances leak out into the seas, they will act as environment protectors, as they promote the development of organisms. Nicotine is transformed to nicotine amid which is the reactive part in NADH and one of the most important substances for the transference of hydrogen. Selenite is reduced to Se（0）, also involved in the transport chain of hydrogen to reducible oxygen. However, large quantities Se（0） may disturb the reactions of sulphur b＇./binding to it and impairing the formation of S-S-bridges.

Research advances in the biological characteristics of the crustacean spermatozoa

The biological characteristics of crustacean spermatozoa is important for the artificial reproduction and genetic breeding. With reference to the latest studies and related materials, this paper reviewed the research progress in the biological characteristics of crustacean spermatozoa, such as morphological structure of sperm, spermatogenesis, sperm viability, preservation in vitro and acrosome reaction et al. The prospects of the research field have also been anticipated.

Changes in Mangrove Epifaunal Assemblages Caused by Forest Logging during Hunting of the Neotropical Cormorant (<i>Phalacrocorax brasilianus</i>) on the Colombian Pacific Coast

Although the importance of mangroves is clearly recognized around the world, these ecosystems are being strongly altered by the logging of their forests for multiple purposes. The Colombian Pacific coast is not an exception to this situation, and apart from the traditional logging of wood, the hunting of the Neotropical Cormorant or Pato-cuervo (Phalacrocorax brasilianus), an activity largely unknown but widespread in the region, is also causing the logging of great extensions of mangroves. The aim of this research was to determine if the assemblages of mollusks and crustaceans of these mangroves are being affected by the hunting of the cormorant. To answer this question, quantitative samplings were realized in four transects in logged and unlogged mangrove areas on the southwestern coast of the Colombian Pacific and diversity, equitability and dominance of macrofaunal assemblages of mangroves were calculated. The data show that although significant differences between diversity indices were not found, there were important differences in equitability (total J’: 0.55 in T1, 0.77 in T2, 0.46 in T3 and 0.65 in T4), specific dominance, and composition of species (T1: 11 species, T2: 13, T3: 9 and T4: 11) between logged and unlogged areas. Based on these results, although forest structure and interstitial salinity were different among transects, we conclude that the present practice of exploitation of the Neotropical Cormorant is affecting the epifaunal populations of mangroves, causing changes in the composition and dominance of species.

Chemical Composition of the Edible Part and the Waste of Brachyuras

Flavorful meat and great economic importance, crabs and swimming crabs are appreciated throughout the Brazilian coast, where its waste is discarded by fishermen and consumers. In order to verify the centesimal composition, these animals caught in Sepetiba Bay （Rio de Janeiro, Brazil）, 20 samples of Ucides cordatus, Cardisoma guanhumi, Menippe nodifrons, Callinectes danae and C. exaperatus had their edible and waste parts （shells and hepatopancreas） analyzed in the Laboratory of Bromatology of the UFRRJ. The analysis revealed that the meat of crustaceans is protein （12.68% to 25.56%） and low in fat （0.37% to 0.67%）, sticking to a more demanding consumer market for thin products; the waste has already presented a protein content ranging from 15.75% to 27.64% and fat from 0.75% to 3.27%, with values of calcium （17.96% to 25.23%） and phosphorus （0.93% to 1.55%）, setting a precedent for use in animal feed through future studies in area.

Toxicity evaluation of produced formation waters after filtration treatment

During the last years many authors have char-acterized the produced formation waters (PFWs) with respect to chemical compounds and toxic-ity. Most of data are related to PFWs collected on offshore platform after treatment process. The available results showed that the particulate phase had an influence on PFW toxicity. As-suming the toxicity of PFWs treated on platform, the aim of this paper is to study the toxicity of these PFWs after a further filtration treatment carried out in laboratory. For this purpose PFWs were sampled from three natural gas platforms located in the Adriatic Sea (Italy) below treat-ment system. The eco-toxicological bioassays have been conducted on test-organisms be-longing to different trophic levels such as bac-teria, algae, crustaceans and fishes. The PFWs resulted toxic according to an overall assess-ment obtained through the bioassays. Further-more, it has been possible to identify the spe-cies that were more sensitive to the tested PFWs, namely Tigriopus fulvus, Dicentrarchus labrax and Vibrio fischeri. Besides, a chemical char-acterization was reported related to the con-taminants present in the PFWs to go with eco-toxicological assessment. Barium, zinc and manganese showed the most concentrations among the metals and the lower molecular weight components were common among the organic compounds. Some differences among PFWs were observed both for toxicity and chemical composition. The highest toxicity was recorded in PFWs (PFW1 and PFW2) containing the highest concentrations of some metals (Ba, Mn and Zn) and/or BTEX.

Heavy metal stress induced hyperglycemia in blue swimmer crab, Portunus pelagicus

The study was to find out the effect of cadmium and mercury on levels of hemolymph glucose, crustacean hyperglycemic hormone（CHH） and hepatopancreas glycogen in the blue swimmer crab Portunus pelagicus. The experiments were performed in both intact and eyestalk ablated crabs. Quantification of CHH was done by the indirect ELISA with the aid of primary anti-Carcinus maenas-CHH antibody. Higher glucose concentration was observed on exposure to 8×10^–6 of cadmium（（825.6±5.42） μg/m L） and 6×10^–6 of mercury（（90.5±6.25） μg/m L）after 48 h and 24 h respectively. Higher level of hemolymph glucose was observed in eyestalk intact crabs on exposure to cadmium and mercury than eyestalk ablated crabs. Decrease in the levels of CHH was observed in both eyestalk intact and ablated crabs on heavy metal exposure. Decline of the hepatopancreas glycogen level was also witnessed with the exposure to heavy metal, which validated its utilization in the production of glucose. Thus this study brings to light, the variations in hemolymph glucose, CHH and hepatopancreas glycogen on heavy metal stress. These carbohydrate metabolites can be used as biomarkers in assessing heavy metal contamination in water bodies.

Seasonal dynamics of crustacean zooplankton community structure in Erhai Lake, a plateau lake, with reference to phytoplankton and environmental factors

The seasonal dynamics of a crustacean zooplankton community in Erhai Lake was investigated from May 2010 to April 2011. In total, 11 species were recorded, including six(6 genera) cladoceran and five(5 genera) copepod species. The crustacean zooplankton densities ranged from 24.3 to 155.4 ind./L. In winter and spring, the large-bodied cladoceran Daphnia galeata dominated the crustacean plankton community. In summer and autumn, when the colonial or filamentous algae dominated the phytoplankton communities, the small-bodied species(e.g. B osmina fatalis, Ceriodaphnia quadrangular, and Mesocyclops leuckarti) replaced the large-bodied ones. One-way ANOVA and redundancy analysis revealed that community structure was dependent upon total nitrogen, total phosphorus, water temperature, transparency, and the biomass of small algae. The variation in both phytoplankton structure and environmental variables were important factors in the seasonal succession of crustacean zooplankton structure in Erhai Lake.

Effects of temperature and salinity on the development of the amphipod crustacean Eogammarus sinensis

The amphipod crustacean Eogammarus sinensis has useful features that make it suitable for use in the aquaculture of fish and large decapod crustaceans.In this study,we investigated the effects of temperature and salinity on the development,fecundity,survival,and growth rate of E.sinensis.The results show that temperature significantly affected E.sinensis development,but salinity.As temperature increased,the duration of E.sinensis embryonic development decreased.Fecundity was affected significantly by temperature and the combination of temperature and salinity,but by salinity alone.In addition,high temperatures accelerated E.sinensis juvenile growth rates,whereas high salinity reduced it.Therefore,our data suggest that E.sinensis tolerates a wide range of salinities and that temperature has more significant effects than salinity on the embryonic development,fecundity,and growth of E.sinensis.Our results shall be useful for mass production of this species for use in aquaculture.

Replacing fishmeal with soybean meal affects survival, antioxidant capacity, intestinal microbiota, and mRNA expression of TOR and S6K1 in Macrobrachium rosenbergii

Using alternative plant-derived dietary protein to replace fishmeal,combined with practical evaluation indexes,is a recent focus for aquaculture practices.An 8-week feeding experiment with giant freshwater prawn Macrobrachium rosenbergii post-larvae was conducted to determine the eff ects of replacing fi shmeal(FM)with soybean meal in the feed,in terms of growth performance,antioxidant capacity,intestinal microbiota,and mRNA expression of target of rapamycin(TOR)and ribosomal protein S6 kinase B1(S6K1).Four isonitrogenous diets with isocaloric value were prepared to contain 100%,75%,50%,or 25%FM as the protein source(dietary treatments FM100,FM75,FM50,and FM25,respectively).Each diet was fed to post-larval prawns(mean weight 0.045±0.002 g)twice a day in four replicates.No signifi cant diff erence in weight gain was observed among all groups,but the survival rate of prawns fed the FM50 and FM25 diets was signifi cantly lower than that of prawns fed the FM diet.The mRNA expression of both TOR and S6K1 were the lowest in hepatopancreas of prawns fed the FM25 diet.Superoxide dismutase activity of prawns fed the FM25 diet was significantly lower than that of prawns fed FM50.In contrast,the malondialdehyde content was signifi cantly higher in prawns fed FM25 as compared with those fed FM75.The proportion of fishmeal in the diet did not affect the composition of core(phylum-level)intestinal microbiota,but greater fishmeal replacement with soybean meal had a potential risk to increase the relative abundance of opportunistic pathogens in the gut when considered at the genus level.These results suggest that fishmeal replacement with soybean meal should not exceed 50%in a diet for post-larval M.rosenbergii.

Size-dependent responses of zooplankton to submerged macrophyte restoration in a subtropical shallow lake

To explore the size-dependent responses of zooplankton to submerged macrophyte restoration, we collected macrophyte, zooplankton and water quality samples seasonally from a subtropical shallow lake from 2010 to 2012. Special attention was given to changes in rotifers and crustaceans （cladocerans and copepods）. The rotifers were grouped into three size classes （〈200 μm, 200μm-400μm, 〉400 μm） to explore their size-related responses to macrophyte restoration. The results showed that during the restoration, the annual mean biomass and macrophyte coverage increased significantly from 0 to 637 g/m2 and 0 to 27%, respectively. In response, the density and biomass of crustaceans and the crustacean-to-rotifer ratio increased significantly, while the rotifer density decreased significantly. Moreover, rotifers showed significant size- dependent responses to macrophyte restoration. Specially, rotifers 〈400 ~tm were significantly suppressed, while those≥400 μm were significantly encouraged. Overall, the population of large-sized zooplankton tended to boom, while that of small rotifers was inhibited during macrophyte restoration. Redundancy analysis （RDA） revealed positive correlations between macrophytes and crustaceans, rotifers and COD or Chl-a, but negative correlations between macrophytes and COD or Chl-a, and between crustaceans and Chl-a. Moreover, the results indicate that increased predation on phytoplankton by large-sized zooplankton might be an important mechanism for macrophyte restoration during development of aquatic ecosystems, and that this mechanism played a very important role in promoting the formation of a clear-water state in subtropical shallow lakes.

Structural changes of oviduct of freshwater shrimp, Macrobrachium nipponense (Decapoda,Palaemonidae), during spawning

The structural change of the oviduct of freshwater shrimp (Macrobrachium nipponense) during spawning was ex- amined by electron microscopy. The oviduct wall structural characteristics seem to be influenced significantly by the spawning process. Before the parturition and ovulation, two types of epithelial cells (types I and II) are found in the epithelium. The free surfaces of type I and type II cells have very dense long microvilli. Under the type I and type II cells, are a relatively thick layer of secreting material and a layer of mostly dead cells. After ovulation, two other types of epithelial cells (types III and IV) are found in the oviduct wall epithelium. The free surface of type III cells only has short microvilli scattered on the surface. The thick layer with secreting material and the dead cell layer disappeared at this stage. In some type III cells, the leaking out of cytoplasm from broken cell membrane led to the death of these type III cells. The transformation of all four types of epithelial cells was in the order: IV→I→II→III.

Diet and feeding ecology of invasive icefish Neosalanx taihuensis in Erhai Lake,a Chinese plateau mesoeutrophicated lake

A comprehensive study of the invasive icefish Neosalanx taihuensis feeding ecology in Erhai Lake was conducted from November 2009 to October 2010. Prey items in the guts of the icefish sampled varied significantly according to season. This finding suggests a relationship between fluctuations in available prey in the environment and selective feeding by icefish. N. taihuensis preferred large-sized zooplankton, such as Daphnia and calanoids. Additionally, the gut fullness values differed significantly （P〈0.001） among sampling times. To compare the values at different times, samples were taken over a 24 h period every 2 months for the entire year. The feeding activities of the fish were concentrated either in the morning （8：00） and/or at dusk （20：00）, except in September 2010. This finding can be explained primarily by the variation in optimum light intensity. Daily N. taihuensis zooplankton consumption varied significantly, both diurnally and among seasons. The daily consumption values ranged from 0.089 to 0.237 g （wet weight） per 100 g wet fish weight in temperatures between 11.50℃ and 24.68℃. This is the first report of diel feeding periodicity and daily food consumption of icefish in their invaded ecosystems.