REVIEW published: 21 October 2021 doi: 10.3389/fmars.2021.746177
Effects of Low Temperature on Shrimp and Crab Physiology, Behavior, and Growth: A Review Xianyun Ren 1,2† , Qiong Wang 1,2† , Huixin Shao 1,2,3 , Yao Xu 1,2,4 , Ping Liu 1,2 and Jian Li 1,2* 1
Key Laboratory for Sustainable Utilization of Marine Fisheries Resources, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China, 2 Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China, 3 College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China, 4 Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
Edited by: Shengming Sun, Shanghai Ocean University, China Reviewed by: Changkao Mu, Ningbo University, China Mario Alberto Burgos-Aceves, University of Salerno, Italy *Correspondence: Jian Li lijian@ysfri.ac.cn † These authors have contributed
equally to this work Specialty section: This article was submitted to Aquatic Physiology, a section of the journal Frontiers in Marine Science Received: 23 July 2021 Accepted: 20 September 2021 Published: 21 October 2021 Citation: Ren X, Wang Q, Shao H, Xu Y, Liu P and Li J (2021) Effects of Low Temperature on Shrimp and Crab Physiology, Behavior, and Growth: A Review. Front. Mar. Sci. 8:746177. doi: 10.3389/fmars.2021.746177
As important aquaculture species worldwide, shrimps and crabs are thermophilic animals with a feeble thermoregulation ability. Changes in environmental factors are the main reason for the decrease in the immunity and disease resistance ability of cultured organisms. Water temperature is one of the most common abiotic stress factors for aquatic ectotherms. It influences nearly all biochemical and physiological processes in crustaceans, resulting in an imbalance in ion and water homeostasis, neuromuscular function loss, cellular dehydration, and altered metabolic pathways. The present review summarizes the current knowledge on the effects of low temperature on the physiological response, and the behavior, development, and growth of shrimp and crab. We suggest a deeper research to understand the physiological processes involved in thermoregulation; this knowledge could be used to reduce the adverse effects in the shrimps and crabs during the culture. Keywords: behavior, cold stress, crab, growth, physiology, shrimp
INTRODUCTION As important aquaculture species worldwide, crustaceans such as shrimp and crab have very weak cold regulation abilities. Since the 1980s, various diseases have caused huge losses in the aquaculture industry. Epidemiological surveys showed that shrimp and crab diseases mainly occurred in spring and summer, and the peak of the disease often occurred after drastic changes in environmental conditions. Changes in environmental factors are the main reason for the decline of biological immunity and disease resistance (Le Moullac and Haffner, 2000). For crustaceans such as shrimp and crab, the water temperature is an important survival-related environmental factor, which not only directly influences their metabolism, growth, molting, and survival, but also affects other environmental factors (e.g., dissolved oxygen) (Chen et al., 1995; Hennig and Andreatta, 1998; Saucedo et al., 2004). Therefore, the temperature has become an essential factor restricting shrimp and crab culture. There has been significant research progress on how temperature affects crustacean growth, physiology, survival, energy metabolism, and biochemistry. In shrimps and crabs, cold shock can be discussed in the context of the general stress response. The present review used the definition of stress reported by Donaldson et al. (2008), which described stress as a cascade of physiological responses occurring in an organism that tries to re- disturbance its homeostasis after
(Hamilton et al., 2007; Zhu and Cooper, 2018). This hypothesis was supported partially by the observation that in Drosophila melanogaster larval heart exposed to cold, only 5-HT had a strong excitatory effect (Zhu et al., 2016). In crustaceans subjected to cold stress, the BA levels are altered. For example, in the giant prawn Macrobrachium rosenbergii, variations in NE levels in the haemolymph, eyestalk, and thoracic ganglion, suggested that NE mediates cold shockinduced hyperglycemia (Hsieh et al., 2006). Higher haemolymph levels of DA were detected in 24◦ C-acclimated white shrimp (Litopenaeus vannamei) when shifted to a lower temperature (18 or 21◦ C) (Pan et al., 2008). The crustacean hyperglycaemic hormone (CHH) family is an important endocrine hormone, comprising CHH, moltinhibiting hormone (MIH), gonad-inhibiting hormone (GIH), and mandibular organ-inhibiting hormone (MOIH) (Chen et al., 2020). In particular, CHH, which mainly regulates the release of glucose, is involved in the mediation of stress responses. CHH is probably the most widely studied neuroendocrine mechanism that mediates the crustacean stress response (Wanlem et al., 2011). CHH is a neurohormone produced by the X-organ sinus gland complex, which is located in the eyestalk, and is regulated by several neuromodulators, e.g., catecholamines (Liu et al., 2008; Aparicio-Simón et al., 2010). DA’s hyperglycemic effects involve CHH (Webster et al., 2012). A hyperglycemic response is also elicited by NE and E and to NE and E also elicit a hyperglycemic response; however, this effect is not dependent on the eyestalk, suggesting that this effect is not mediated by CHH or is mediated by non-eyestalk produced CHH (Si et al., 2019). A significant increase in CHH levels in the haemolymph in response to cold stress have been reported in several crustaceans, including the L. vannamei (Lago-Lestón et al., 2007) and the freshwater crayfish, Cherax quadricarinatus (Prymaczok et al., 2016).
an insult. There are three broad categories of responses to environmental stress: primary (e.g., the release of corticosteroids and catecholamine and the neuroendocrine response), secondary (e.g., immunological, osmoregulatory, hematological, cellular, and metabolic changes), and tertiary (e.g., behavioral and physiological stress responses in the whole organism). This paper reviews the research progress of the effects of temperature from the three aspects (see Figure 1), which will enrich the basic physiological data of shrimp and crab, and to guide the artificial culture of shrimp and crab, providing a reference for related research in the future.
PRIMARY RESPONSES – THE NEUROENDOCRINE RESPONSE The endocrine and nervous systems function synchronously to regulate many physiological processes and to maintain balanced organism-wide homeostasis in both normal and stressful conditions, via a process, termed neuroendocrine integration (Adamski et al., 2019). The neuroendocrine system and its related signaling molecules (e.g., biogenic amines (BAs) and neuropeptides) regulate many crustacea behavioral and physiological processes; therefore, they might also affect cold tolerance (Chen et al., 2014). BAs identified in crustaceans include catecholamines [dopamine (DA), norepinephrine (NE), and epinephrine (E)] and indoleamine [5-hydroxytryptamine (5-HT)] (Chang et al., 2009, 2015). The stress response involves BAs (Zhao et al., 2016). For instance, low temperatures alter BA concentrations, allowing insects to survive in, or prepare for, unfavorable conditions such as prolonged stress. BAs have important functions in the regulation of fundamental life processes (Sinakevitch et al., 2018). Not only do BAs function as neuromodulators and neurotransmitters in nervous tissues, but also can act as neurohormones after their release into body fluids (Sinakevitch et al., 2018). According to the target tissue, BAs bind to different types of G protein-coupled receptors (GPCRs), resulting in the stimulation of various secondary messengers, such as Ca2+ or cyclic adenosine monophosphate (cAMP) (Farooqui, 2012). Research has identified four DA and five 5-HT receptor subtypes in crustaceans to date (Northcutt et al., 2016; Pang et al., 2019). Most of these receptors are member of a GPCR superfamily that activates cascades of second messengers, mainly protein kinase A (PKA) and cAMP (Costa et al., 2016). In crayfish (Procambarus clarkii), agonistic behavior, such as the loser and winner effects is mediated by the cAMP-PKA signaling pathway (Momohara et al., 2016). BAs’ neuroprotective role in supporting muscle activity in various crustaceans in response to low temperature has been studied (Hamilton et al., 2007). In lobster and crayfish muscles, increased haemolymph 5-HT levels in response to cold resulted in an increase in the amplitude of the excitatory postsynaptic potential (EPSP). BAs’ effects are frequently temperaturedependent; e.g., 5-HT-induced alterations of the EPSP occur only at suboptimal temperatures, which might aid the function of neuromuscular junctions under low temperature stress
SECONDARY RESPONSES – CHANGES IN METABOLISM, THE IMMUNE SYSTEM, AND OSMOREGULATION Low temperature is closely related to the immune and antioxidant system of shrimps and crabs (see Table 1), and is the most important stress factor in aquaculture (Xu et al., 2019). Low temperature not only causes a disorder of free radical metabolism, damage the normal physiological function and immune defense ability of cells and tissues, and directly affects the metabolism of aquatic animals, but also affect dissolved oxygen and other environmental factors, thus leading to the susceptibility of shrimps and crabs to pathogens.
Effects of Low Temperature on Metabolism Temperature can directly affect the respiration and energy metabolism of crustaceans. Under low temperature stress, on the one hand, energy consumption increases. On the other hand, neurohormone secretion and digestive enzyme activity decrease, and energy metabolism-related enzyme activity and
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FIGURE 1 | Schematic representation of natural and anthropogenic sources of cold shock and the primary, secondary and tertiary responses to cold shock.
Membrane fatty acid desaturation is considered an important mechanism by which crustaceans adapt to low temperature, and is crucial to maintain membrane fluidity, enzyme activity, and normal cell function (Pruitt, 1990; Suprayudi et al., 2004). Cold stress leads to a change in the fatty acid (FA) composition in crustacean cells, which usually leads to the decrease in the saturated fatty acid (SFA) ratio and a rapid increase in the unsaturated fatty acid (UFA) ratio, which is conducive to the maintenance of cell membrane fluidity (Azra et al., 2020a,b). In Scylla serrata, Cancer pagurus, and Carcinus maenas, the SFA content decreased significantly at low temperature (Cuculescu et al., 1995; Wang et al., 2007). In the crayfish cultured at low temperatures, the haemolymph cholesterol and triglyceride contents were reduced significantly, suggesting that under cold stress, these two substances are consumed to release energy (Wu et al., 2020). UFAs are important components of cellular membranes and participate in energy metabolism (Nemeth et al., 2014). Under cold stress, UFA levels increased in L. vannamei (Fan et al., 2019), the Chinese fleshy shrimp (Fenneropenaeus chinensis) (Meng et al., 2019), and the kuruma shrimp (Marsupenaeus japonicas) (Ren et al., 2020). Desaturase enzymes play an important role in the synthesis of unsaturated fatty acids. In C. quadricarinatus low temperature treatment increased 16 desaturase mRNA expression and enzyme activity with decreasing water temperature (Wu et al., 2018). However, the mechanisms for the induction of 16 desaturases at low temperature remain unclear. As an important energy source, sugar plays a vital role in the low temperature stress of shrimp and crab. A decrease in temperature led to an increased blood glucose content and a decreased glycogen content in M. rosenbergii, S. serrata, Pachygrapus crassipesran Dall, Paranephrops planfrons, and L. vannamei (Hsieh et al., 2006; Kong et al., 2008;
metabolic modes are altered, resulting in crustacean metabolic disorder (Anestis et al., 2008). Low temperatures are believed to have widespread effects on marine organisms’ behavioral and physical traits, including their metabolism. Generally, crustaceans lack efficient regulators, making them sensitive to reduced temperatures. In shrimp and crab, proteins are the primary energy source (Cuzon et al., 2010). In cold-adapted L. vannamei, fat absorption and digestion, and the protein pathways were enhanced significantly (He et al., 2018). Similarly, under cold stress (23◦ C), plasma lipids (especially total cholesterol and triglycerides) and total proteins increased significantly; there were no significant changes in glucose levels (Wu et al., 2020). Therefore, it was speculated that in crustaceans under acute cold-stress, lipids and proteins are the main energy sources (Wang et al., 2019). A metabolic study of the black tiger shrimp (Penaeus monodon) cultured under low temperature revealed that its amino acid and trehalose contents increased significantly (Jiang et al., 2019). Under low temperature stress, in addition to the fatty acid composition of tissues and cells, the content of free amino acids (FAA) in tissues also changed. The content of total FAA increased in spring and autumn, but decreased rapidly in winter. As an important nutrient in the body, protein may be automatically decomposed into amino acids under low temperature stimulation. On the one hand, amino acids are used for protein synthesis and turnover, and on the other hand, they might have anti-stress functions. To improve the metabolic rate and oxygen carrying capacity of the body, or to meet the needs of protein synthesis, the structure and synthesis rate of hemocyanin in shrimp and crab will change significantly in response to stress. The fatty acid metabolism of crustaceans is sensitive to temperature. Cold temperature mainly affects membrane fluidity by affecting the saturation of fatty acids in the cell membrane.
effects on shrimp disease tolerance and survival. However, to date, there have been few studies investigating the immune regulatory mechanisms in shrimp exposed to low temperature. Lysozyme (LSZ), as a kind of hydrolase, is the basis of phagocyte sterilization, existing widely in different tissues, body fluids, and secretions of various organisms, and can be used to measure the non-specific immune capacity of organisms (Mock and Peters, 1990). Low temperature can affect the activity of LSZ. Ding et al. (2010) reported that temperature change could inhibit the LSZ activity of S. serrata. In the red claw crayfish, LSZ was inhibited significantly following low temperature exposure (Wu et al., 2019). Hemocyanins are extracellular negatively charged proteins that are involved in numerous physiological functions, such as protein storage, osmoregulation, oxygen transport, and enzyme activities (Ishwarya et al., 2018; Coates and Costa-Paiva, 2020). In the crayfish P. clarkii and P. zonangulus, the acclimation temperature directly affected the hemocyanin binding affinity (Powell and Watts, 2006). Thus, it is believed that shrimp are more susceptible to pathogens under low temperature conditions.
Valle et al., 2009; Zhou et al., 2011). This change in sugar levels in shrimp and crab is an adaptation to low temperature. During cold stress, glucose is consumed as a fast energy source, and the hepatopancreas continuously decomposes glycogen to meet the needs of maintaining the metabolic energy supply. When the temperature rises, or the crustacean adapts to low temperature, the haemolymph glucose level will gradually recover.
Effects of Low Temperature on Immune System The crustacean immune system mainly functions via innate immune mechanisms comprising humoral and cellular responses. Cellular innate immunity comprises all hemocytemediated reactions (e.g., phagocytosis, nodule formation, and encapsulation). Humoral innate immunity comprises mainly lysozyme, phosphatases, antimicrobial peptides (AMPs), protease inhibitors, agglutinins, and the prophenoloxidase-activating system (Kenneth and Lage, 1992; Kulkarni et al., 2020). In the humoral response, AMPs, lysozyme, or phenoloxidase (PO) concentrations increase markedly under stress conditions, e.g., invasive pathogens, disease outbreaks, and environmental hazards. Hemocytes comprise the major component of the crustacean cellular immune system, and their levels will change according to the condition of the organism and the environment (Wang and Chen, 2006). Thus, stress-induced immune system activity is conveniently assessed using the total haemocyte count (THC) (Xu et al., 2019). Fan et al. (2013) found that the THC in L. vannamei was reduced when the temperature decreased from 28 to 13◦ C. These results indicated that the THC of crustaceans is closely related to temperature. The lower the temperature, the lower the enzyme activity and the lower the THC. In lobsters, the hemocyte phagocytic activity was affected negatively by low temperature (Steenbergen et al., 1978). The evolutionarily conserved cellular process of autophagy involves maintaining homeostasis by recycling damaged or excess cellular components (e.g., misfolded proteins, intracellular pathogens, damaged organelles, and damaged DNA) (Bolliet et al., 2017). In L. vannamei, autophagy is associated with low temperatures (Liang et al., 2020). In invertebrates, the important innate immune response mechanism, melanization, functions via the prophenoloxidase (proPO)-activating system and is catalyzed by PO (Amparyup et al., 2013). In shrimp, melanization has been suggested to be an antiviral response (Zhao et al., 2020). Meanwhile, PO functions in cellular defense in association with phagocytosis-enhancing factors; therefore, PO is used frequently to assess the effect of environmental stress on the invertebrate immune system (Ellis et al., 2011). In brown shrimp (Penaeus californiensis) exposed to increasing temperature (18−32◦ C), the hemocyte proPO system activity decreased at 32◦ C (Vargas-Albores et al., 2008). In the crab (Carcinus aestuarii), when incubated at 4◦ C, the PO activity in cell-free haemolymph was significantly higher than that in the control crabs incubated at 17◦ C (p < 0.05) (Matozzo et al., 2011). In addition, immune parameters, such as antibacterial activity, are suppressed by low temperature. Taken together, these previous studies show that low temperature has important
Effects of Low Temperature on the Antioxidant System In healthy organisms, the production and elimination of free radicals are in a dynamic balance; however, in adversity, stress will induce a reaction from the enzyme systems and non-enzyme systems of mitochondria, microsomes, and the cytoplasm, resulting in the production of excess reactive oxygen species (ROS) and oxygen free radicals, thus breaking the balance of reactive oxygen metabolism (Wade et al., 2017). In cells and tissues, oxidative stress’s effects on cellular damage can be indicated by the level of lipid peroxidation (Mensah et al., 2012). To reduce oxidative stress and repair damaged cells, the primary defense response comprises the production of enzymatic and non-enzymatic antioxidants to scavenge ROS and free radicals (El-Gendy et al., 2010). In all organisms, the main antioxidative enzymes that detoxify ROS are glutathione S-transferase (GST), glutathione reductase (GR), catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD), in addition to the non-enzymatic antioxidant molecule, reduced glutathione (GSH) (Lesser, 2006; Zheng et al., 2019). In mud crabs subjected to cold stress, the CAT, SOD, and GPX activities increased over 2 h, and then decreased gradually; the content of malondialdehyde (MDA) also increased gradually under cold stress (Kong et al., 2007). In S. paramamosain acclimated at 5, 10, 15, and 27◦ C (control group), the SOD, CAT, and GPx activities, and the MDA content decreased gradually with lowering temperatures and were significantly reduced at 5 and 10◦ C compared with those in crabs incubated at 27◦ C (Kong et al., 2012). Qiu et al. (2011) evaluated the physiological effects of continuous temperature decrease on L. vannamei. The MDA level increased when water temperature decreased from 23 to 12◦ C. It has become clear that organisms share a common adaptation mechanism, termed the heat shock response (HSR), to cope with temperature-induced stress, which results in a dramatic change in gene expression patterns and leads to the elevated synthesis of a range of molecular chaperones and the induction
might involve p53 (Ren et al., 2020). Significant changes in p53 signaling pathways under cold stress were also observed in the hepatopancreas of the red claw crayfish under cold stress (Wu et al., 2019).
of other cell-protective pathways (Richter et al., 2010). The heat shock protein (HSP) and heat shock factor (HSF)- mediated regulation pathways play crucial roles in the HSR, and have been studied intensively in terms of HSR mechanisms and the cold-tolerance of organisms (Gbotsyo et al., 2020). HSPs are regulated by heat shock elements (HSEs), HSFs, and other factors to control their cellular levels (Morimoto and Santoro, 1998). HSF1 is an important transcription factor that regulates the heat shock response, and is expressed widely in eukaryotes, playing an important role in maintaining intracellular homeostasis during heat stress (Anckar and Sistonen, 2011). When the body is subjected to cold stress, it combines with HSE. In addition, HSPs are conserved at the evolutionary level. In a study of high temperature stress of Penaeus monodon, PmHSF1 expression was elevated. The expression levels of HSPs and other heat tolerance related genes in P. monodon changed significantly after the PmHSF1 gene was knocked down (Sornchuer et al., 2018). In M. japonicas, MjHSF1 transcription was upregulated under heat stress (Zheng et al., 2020). To date, most of the studies on the related functions of HSF1 have focused on the interaction between HSF1 and HSPs, and there are few studies on the expression of immune related factors associated with HSF1. Several HSP genes are downstream targets of HSF1, which are involved in crustacean resistance to adverse environments. HSPs comprise molecular chaperones that are produced during the exposure to, and recovery from environmental or physiological stress, including cold stress (Johnston et al., 2018). HSPs, also referred to as molecular chaperones or stress proteins, comprise a group of highly conserved proteins that are present ubiquitously in both prokaryotic and eukaryotic organisms (Roberts et al., 2010). HSPs protect cellular functions and structures and from the effects of stress and have important functions in the maintenance of cellular homeostasis (Morimoto and Santoro, 1998). Based on their molecular weight, HSPs are generally classified into five families, HSP100, HSP90, HSP70, HSP60, and small HSPs (Ahn and Im, 2020). In F. chinensis, the levels of FcHSP90 mRNA were induced sensitively in response to heat shock (from 25 to 35◦ C), reaching a maximum level after 6 h of heat shock (Li et al., 2009). In other crustaceans (S. serrata and L. vannamei) mRNA levels of HSP40, HSP70, or HSP90 were increased in response to cold or heat shock (Fu et al., 2013; Chen et al., 2018; Sung et al., 2018; Fan et al., 2019). Apoptosis, a cell death process, has a crucial function in maintaining tissue hemostasis and disease protection. As a component of inflammatory reactions, the physiological function of apoptosis helps to remove damaged or harmful cells from immune tissues (Johnstone et al., 2002). Li et al. (2014) evaluated the effect of continuous temperature decrease on hemocyte apoptosis of L. vannamei, which showed an increase in the apoptotic cell ratio and a decrease in caspase3 activity when the water temperature was reduced from 27 to 17◦ C. Cold temperature led to increase caspase-3 expression in the swimming crab (Portunus trituberculatus) (Meng et al., 2014). A previous study from our group demonstrated that in M. japonicus, the expression of p53 increased significantly under cold stress, which suggested that cold-induced apoptosis
Low Temperature’s Effects on Osmoregulation During cold acclimation (or low temperature adaptation), shrimps and crabs change the composition and concentration of intracellular ions by regulating the number and distribution of various ion channels on the cell membrane and changing the composition and concentration of intracellular ions to maintain normal physiological activities (Masroor et al., 2018). On the gill cell membrane of S. serrata, four kinds of adenosine triphosphatases (Ca2+ /Mg2+ -ATPase, Ca2+ -ATPase, Mg2+ -ATPase, and Na+ /K+ -ATPase), which are involved in ion uptake and osmotic pressure regulation, were upregulated during the process of adaptation to a lower temperature (Kong et al., 2012). In the hepatopancreas of M. nipponense, the Na+ K+ ATPase activity in the temperature range 16−22◦ C was enhanced by 1.38-fold compared with that in the temperature range 25−32◦ C (Wang et al., 2006). In Procambarus clarkia, exposure from room temperature (23◦ C) to 4◦ C for 28 days resulted in a significant increase in Ca2+ -ATPase activity (Gao et al., 2009). Thus, in a cold environment, shrimps and crabs can reduce heat loss by adjusting the ionic concentration and osmotic pressure of their body fluid to reduce the difference between their body temperature and that of the outside water.
LEVEL THREE – CHANGES IN BEHAVIORAL AND GROWTH RESPONSES Temperature is a basic environmental factor that limits species distribution, affecting individual growth and determining the reproductive cycle. How shrimps and crabs adapt to temperature change and maintain a steady state of life process is a longterm scientific problem. Low temperature has adverse effects on the growth and development of organisms (Shields, 2019). The temperature adaptation range of an organism is an important character in aquaculture. Improving tolerance to temperature stress is a challenging problem in aquaculture breeding. In the rock crab (Cancer irroratus), progressive temperature increase caused their heart rate to increase between 12 and 26◦ C, peaking at 153 ± 27 beats min−1 at 26◦ C (Frederich et al., 2009). The molting and reproduction of crustaceans are also affected by temperature. The lower the taxonomic position of the organism, the more susceptible it is to temperature. Therefore, to regulate the reproductive physiology of crustaceans, water temperature is an important factor.
Effect of Temperature on Shrimp and Crab Embryonic Development The embryonic development of crustaceans is a dynamic physiological process. In addition to the influence of the 5 October 2021 | Volume 8 | Article 746177
Ren et al. Low Temperature’s Effects on Crustaceans
TABLE 1 | Effects of low temperature on immune and antioxidant parameters in shrimp and crab. Organism Species Shrimp Litopenaeus vannamei Crab Size/life stage Temperature Factor Tissue