**4. Growth**

212 Pesticides in the Modern World - Risks and Benefits

undergoes several stages up to the juvenile stage. Freshwater environments impose a severe osmotic stress on unprotected eggs and the free larvae stage. In the same way, developing embryos must be protected against this stress. When they conquered these environments, decapods developed different strategies to protect eggs and embryos. The primitive pelagic larval phases were suppressed; larval stages occur inside the egg, and the offspring hatch as mysis or juveniles. This internal development (i.e., inside the egg) imposes a greater protection to embryos against environmental pressures, especially in the susceptible larval stages. To support these internal stages, eggs increased in size and energy resources, mainly lipoproteins, because embryos grow inside the eggs and use their internal energy resources. Freshwater decapod females carry their eggs in the pleon, protecting them until the larvae or juveniles hatch. Because of their increased size, the number of eggs that a female can carry decreased, resulting in a concomitant decrease in the number of offspring (Ruppert &

Several pesticides are highly lipophilic and are accumulated mainly in lipid reserves. During ovary development, oocytes accumulate lipids and lipoproteins, mainly lipovitellin, forming the vellum, which in turn will be used by the embryo as an energetic resource (the embryo "feeds" on the vellum). Attached to the lipovitellins, pesticides enter to the oocytes and accumulate on them. One explanation for the relatively greater resistance of females to organic pollutants is the distribution of these toxicants in the ovary, decreasing their concentrations in vital organs such as the hepatopancreas and delaying death (Sheridan, 1975; Menone et al., 2000; Wirth et al., 2001; Menone et al., 2004, 2006; Santos de Souza et al., 2008). The presence of pesticides in the oocytes implies that the embryo, beginning with fertilisation, is exposed to pesticides. Embryos grow and feed on the lipid reserves present on the vellum, with the consequent intake of pesticides. This may provoke not only the death of the embryos, with the release of dead eggs by the female, but also sublethal effects, such as abnormal size in eggs; deformation of embryos, such as tissue dropsy, atrophy, abnormal or depigmented eyes; and abnormalities in the pleon, telson, and spine, pereiopods and pleopods (Rodriguez et al., 1994; Saravana Bhavan & Geraldine, 2001). Deformation may cause difficulties in hatching or in brood survival, as activities such as swimming and searching for prey or escaping from predators may be hampered, and even moulting may not be successfully completed (Fig.

In the case of freshwater decapods, the amount of vittelins and the time that embryos spend inside the eggs are greater than found in their marine relatives. This provokes an extended exposure time to different concentrations of pesticides, which depends on the exposure of females during gonad development and pesticide concentration in the

Because of the osmotic stress that freshwater environments present, freshwater decapods possess a thicker chorion for protecting embryos from external aggressions. This chorion also protects them from biocides, making eggs as resistant as adults in some freshwater prawns and crabs, leaving juveniles as the most vulnerable (Key et al., 2003; Li et al., 2006). When the embryo is close to hatching, the chorion narrows to allow embryos to hatch, also allowing external agents to come into contact with embryos, making them more vulnerable to external agents, as observed in the prawn, *Palaemonetes argentinus*

Barnes, 1994; Lee & Bell, 1999).

6).

ovaries.

(Ituarte et al., 2005).

Growth is an interesting aspect in decapods in that it includes both internal and external factors. The intermoult period and increase in size are affected by different factors, such as diet (mainly protein, and lipid level variation), interspecific interactions (searching for agonistic behaviour and hierarchical conditions), temperature, biocides (or xenobiotic elements). Moreover, the growth in many species shows isometry and/or allometry variations in the ontogeny, and thus growth pattern can be affected. The study methods are different according to a study's objectives. In some cases, the animals are evaluated in groups, e.g., with diets; in other cases, a study is conducted with isolated animals to observe the xenobiotic effects on growth through chronic assays.

The capacity of an organism for survival, growth, and reproduction involves competition for energy resources at the individual level (Schmidt-Nielsen, 1997). Toxicant-induced shifts in energy allocations to these life-history activities will have important consequences on population. For example, higher respiration rates of estuarine crustaceans sublethally exposed to a variety of pesticides reduced juvenile growth by lowering growth efficiency rates, suggesting that increased metabolic demands lowered the amount of assimilated energy available for production of new tissue (McKenney & Hamaker, 1984; McKenney & Matthews, 1990). The assessment of changes in growth and energy stores of toxicantsensitive life stages have a direct link to ecological consequences of environmental stress and can be useful as biomarkers to diagnose early damage in aquatic populations (Newman & Unger, 2003).

Freshwater Decapods and Pesticides: An Unavoidable Relation in the Modern World 215

Some pesticides are acetylcholinesterase inhibitors in crustaceans and other animals (Saravana Bhavan & Geraldine, 2001; Braga da Fonseca et al., 2008). The inhibition of this enzyme enhances the contraction of skeletal muscles and impairs movement. When exposed to biocides that provoke an acetylcholinesterase inhibition, decapods are affected in their vital, locomotive and behavioural actions, with several different implications for the individual and the community. A prawn, crab or crayfish that is not able to swim or run correctly will be more susceptible to predation. Freshwater prawns and crabs exposed to acetylcholinesterase inhibitor biocides had a stimulus that improves appendage movements. Nevertheless, these movements are not synchronised, and the total movement efficiency is lower than that of normal locomotion. Prawn jumps are uncontrolled, and they keep jumping in the same place, without escaping from the area; crabs walking becomes frenetic, and they jump and walk, but move more slowly than normal. The increasing of impaired movements, which provokes a greater demand on muscle activity, more rapidly tires the affected animals. After the initial excitation, animals become quiet because of this tiredness, with slower movements and even immobility, making them more susceptible to predation (Williner & Collins, 2003; Collins et al., 2004; Collins & Cappello, 2006; Montagna & Collins, 2008). In a natural environment, escape from natural predators will be more difficult if crustaceans are affected by this kind of biocide, enhancing predation and decreasing the

Moreover, impaired movements not only affect locomotion as a way of escaping from the risk area but also affect the capacity of crustaceans to quickly locate refuges. Some freshwater crabs are pleustonic; they live between the roots of aquatic plants. As these roots act as filters for suspended organic matter and planktonic organisms, crabs go to the periphery for feeding. When detecting predators, they quickly migrate to the inside of the roots or stay still as a way of camouflage. Prawns and crabs also use rocks or burrows as refuges, either made by themselves or by other animals, and they swim or run to these refuges or bury themselves when they detect predators. Some crabs, especially the bigger species, use their chelipeds to attack their predators as a way of intimidating them and allowing themselves to flee (Collins et al. 2006, Collins et al., 2007). All these actions require a complex sequence of movements. If these decapods are affected by biocides, uncoordinated movements or tiredness will hinder their ability to find refuges, leading to

Coordination of movements is not only necessary for escaping predators but also for finding food resources. Freshwater crabs and prawns are omnivorous animals. Some groups are specialised to filter sand and clay, feeding on the microbiota inhabiting these sediments. Other groups eat algae, macrophytes and animals tissues. Animal food may come from carrion or from hunting live prey. Decapod prey includes insect larvae, cladocerans, copepods, benthic organisms such as annelids and molluscs, fishes, other crustaceans and even eggs, juveniles and adults of the same species (Collins et al., 2006,

The hunting of mobile prey, such as fishes and crustaceans, and the manipulation of molluscs, which enclose themselves in their shells, requires both coordination in movements and strength. These actions become more difficult if decapods are subjected to acetylcholinesterase inhibitors or narcotic pesticides, decreasing the feeding capacity. Combining this decreased feed capacity with the increase in the energetic expenditure provoked by the impaired movements, biocide exposure eventually causes a depletion in

increased predation and decreasing the population (Fig. 7).

population.

Collins et al., 2007).

Crustaceans do not grow continuously but by periodically shedding the hard exoskeleton in a process called moult or ecdysis. Moulting is a very important physiological process because it not only allows for growth and development of these animals, which possess a rigid, confining exoskeleton but is also tied to metamorphosis during the early stages of the life cycle and reproduction during the adult stage (Passano, 1960). The process of ecdysis of decapod crustaceans is an antagonistic interaction by ecdysone and the MIH (moult inhibiting hormone), which originates from the Y-organ and X-organ/sinus gland (XO/SG) complex, respectively. The X-organ/sinus gland complex is located within the eyestalks. A reduction in MIH in the haemolymph is believed to induce moulting and stimulate the Yorgans to synthesise and secrete ecdysone, which will be converted to the active moulting hormone 20-HE (20-Hydroxyecdysone). Moreover, a significantly lower level of 20-HE was recorded in the haemolymph during the interval of moulting (Chang, 1995).

Limb regeneration is also an aspect of moulting. In this case, the regenerate first develops as a limb bud folded within a layer of cuticle and becomes free to unfold when the individual undergoes ecdysis as part of the moulting process (Fingerman et al., 1998). However, low levels of pollutants (such as chlorinated compounds) had an inhibitory effect on moulting and limb regeneration in some decapods (Fingerman ,1985).

Growth rate is usually described in terms of independent moult periods. These consist of a description of the size increment for each individual moult (moult increment) and a description of the time increment between moults (intermoult period) (Hartnoll, 1982). In many decapod species, growth alterations by toxicant may be caused by variations in the moult increment, but principally by changes in the intermoult duration. A reduction in growth by the lengthening of the intermoult period was observed in juvenile prawns, *Palaemonetes argentinus,* during the first moult cycles exposed to cypermethrin (Collins & Cappello, 2006) and to chlorpyrifos and endosulfan insecticides (Montagna & Collins, 2007). In contrast, this same freshwater prawn showed a shortening in the intermoult period with a reduction in the moult increment at the highest concentration of glyphosate tested (0.070 ml l-1) (Montagna & Collins, 2005). These changes may involve perturbations to the X-organ and the sinus gland, which affect the production and storage of the inhibitory moult hormone or, more integrally, the neurohormonal system located in the eyestalks. Snyder & Mulder (2001) reported a delay in the onset of moulting of larvae of the lobster, *Homarus americanus,* exposed to heptachlor. This delay was correlated with both reduced levels of circulating ecdysteroids and increases of some P450-dependent detoxifying enzymes. Although it is known that 20-hydroxyecdysone itself can induce the expression of these enzymes, it is quite possible that this induction can also be produced by some toxicants.

#### **5. Biocide effects on behaviour**

Among the movements made by an animal, there are vital movements, such as breathing and cardiac movements; locomotive movements for prey finding and predator escaping; and behavioural movements, such as courtship and copulation. Every movement, even the simplest, depends on the harmony of every single movement to complete a desired action, i.e., for swimming, a prawn needs each pleopod to move in the right direction at the right time and with the right intensity to accomplish the final desired movement. Movements are transmitted through the nervous system and the synaptic gap by neurotransmitters, such as acetylcholine, while they are inhibited by enzymes, such as acetylcholinesterase, which stops the nerve impulse.

Crustaceans do not grow continuously but by periodically shedding the hard exoskeleton in a process called moult or ecdysis. Moulting is a very important physiological process because it not only allows for growth and development of these animals, which possess a rigid, confining exoskeleton but is also tied to metamorphosis during the early stages of the life cycle and reproduction during the adult stage (Passano, 1960). The process of ecdysis of decapod crustaceans is an antagonistic interaction by ecdysone and the MIH (moult inhibiting hormone), which originates from the Y-organ and X-organ/sinus gland (XO/SG) complex, respectively. The X-organ/sinus gland complex is located within the eyestalks. A reduction in MIH in the haemolymph is believed to induce moulting and stimulate the Yorgans to synthesise and secrete ecdysone, which will be converted to the active moulting hormone 20-HE (20-Hydroxyecdysone). Moreover, a significantly lower level of 20-HE was

Limb regeneration is also an aspect of moulting. In this case, the regenerate first develops as a limb bud folded within a layer of cuticle and becomes free to unfold when the individual undergoes ecdysis as part of the moulting process (Fingerman et al., 1998). However, low levels of pollutants (such as chlorinated compounds) had an inhibitory effect on moulting

Growth rate is usually described in terms of independent moult periods. These consist of a description of the size increment for each individual moult (moult increment) and a description of the time increment between moults (intermoult period) (Hartnoll, 1982). In many decapod species, growth alterations by toxicant may be caused by variations in the moult increment, but principally by changes in the intermoult duration. A reduction in growth by the lengthening of the intermoult period was observed in juvenile prawns, *Palaemonetes argentinus,* during the first moult cycles exposed to cypermethrin (Collins & Cappello, 2006) and to chlorpyrifos and endosulfan insecticides (Montagna & Collins, 2007). In contrast, this same freshwater prawn showed a shortening in the intermoult period with a reduction in the moult increment at the highest concentration of glyphosate tested (0.070 ml l-1) (Montagna & Collins, 2005). These changes may involve perturbations to the X-organ and the sinus gland, which affect the production and storage of the inhibitory moult hormone or, more integrally, the neurohormonal system located in the eyestalks. Snyder & Mulder (2001) reported a delay in the onset of moulting of larvae of the lobster, *Homarus americanus,* exposed to heptachlor. This delay was correlated with both reduced levels of circulating ecdysteroids and increases of some P450-dependent detoxifying enzymes. Although it is known that 20-hydroxyecdysone itself can induce the expression of these enzymes, it is quite possible that this induction can also be produced by some toxicants.

Among the movements made by an animal, there are vital movements, such as breathing and cardiac movements; locomotive movements for prey finding and predator escaping; and behavioural movements, such as courtship and copulation. Every movement, even the simplest, depends on the harmony of every single movement to complete a desired action, i.e., for swimming, a prawn needs each pleopod to move in the right direction at the right time and with the right intensity to accomplish the final desired movement. Movements are transmitted through the nervous system and the synaptic gap by neurotransmitters, such as acetylcholine, while they are inhibited by enzymes, such as acetylcholinesterase, which

recorded in the haemolymph during the interval of moulting (Chang, 1995).

and limb regeneration in some decapods (Fingerman ,1985).

**5. Biocide effects on behaviour** 

stops the nerve impulse.

Some pesticides are acetylcholinesterase inhibitors in crustaceans and other animals (Saravana Bhavan & Geraldine, 2001; Braga da Fonseca et al., 2008). The inhibition of this enzyme enhances the contraction of skeletal muscles and impairs movement. When exposed to biocides that provoke an acetylcholinesterase inhibition, decapods are affected in their vital, locomotive and behavioural actions, with several different implications for the individual and the community. A prawn, crab or crayfish that is not able to swim or run correctly will be more susceptible to predation. Freshwater prawns and crabs exposed to acetylcholinesterase inhibitor biocides had a stimulus that improves appendage movements. Nevertheless, these movements are not synchronised, and the total movement efficiency is lower than that of normal locomotion. Prawn jumps are uncontrolled, and they keep jumping in the same place, without escaping from the area; crabs walking becomes frenetic, and they jump and walk, but move more slowly than normal. The increasing of impaired movements, which provokes a greater demand on muscle activity, more rapidly tires the affected animals. After the initial excitation, animals become quiet because of this tiredness, with slower movements and even immobility, making them more susceptible to predation (Williner & Collins, 2003; Collins et al., 2004; Collins & Cappello, 2006; Montagna & Collins, 2008). In a natural environment, escape from natural predators will be more difficult if crustaceans are affected by this kind of biocide, enhancing predation and decreasing the population.

Moreover, impaired movements not only affect locomotion as a way of escaping from the risk area but also affect the capacity of crustaceans to quickly locate refuges. Some freshwater crabs are pleustonic; they live between the roots of aquatic plants. As these roots act as filters for suspended organic matter and planktonic organisms, crabs go to the periphery for feeding. When detecting predators, they quickly migrate to the inside of the roots or stay still as a way of camouflage. Prawns and crabs also use rocks or burrows as refuges, either made by themselves or by other animals, and they swim or run to these refuges or bury themselves when they detect predators. Some crabs, especially the bigger species, use their chelipeds to attack their predators as a way of intimidating them and allowing themselves to flee (Collins et al. 2006, Collins et al., 2007). All these actions require a complex sequence of movements. If these decapods are affected by biocides, uncoordinated movements or tiredness will hinder their ability to find refuges, leading to increased predation and decreasing the population (Fig. 7).

Coordination of movements is not only necessary for escaping predators but also for finding food resources. Freshwater crabs and prawns are omnivorous animals. Some groups are specialised to filter sand and clay, feeding on the microbiota inhabiting these sediments. Other groups eat algae, macrophytes and animals tissues. Animal food may come from carrion or from hunting live prey. Decapod prey includes insect larvae, cladocerans, copepods, benthic organisms such as annelids and molluscs, fishes, other crustaceans and even eggs, juveniles and adults of the same species (Collins et al., 2006, Collins et al., 2007).

The hunting of mobile prey, such as fishes and crustaceans, and the manipulation of molluscs, which enclose themselves in their shells, requires both coordination in movements and strength. These actions become more difficult if decapods are subjected to acetylcholinesterase inhibitors or narcotic pesticides, decreasing the feeding capacity. Combining this decreased feed capacity with the increase in the energetic expenditure provoked by the impaired movements, biocide exposure eventually causes a depletion in

Freshwater Decapods and Pesticides: An Unavoidable Relation in the Modern World 217

bad eggs or foreign particles or microorganisms entering via the same motions for the

Fig. 7. Different effects that can occur when the animals are expose to biocide in relationship to oxygen consumption, activities, movements, and reproduction. All these affect the fitness

Biocides are known to affect moulting events in some decapod crustaceans, affecting their growth and keeping many adult individuals in sizes below the average body size of conspecifics. It is estimated that the size of individuals is an important factor in mate choice, as there is a direct relationship in many crustaceans between adult size and the number of eggs a female is capable of carrying, so the effect of biocides may include the number of

In assessing organisational levels, it is necessary to analyse those relationships beyond the physical dimension of the animal's body and that provoke the defined interactions. Among these relationships are the connections between the various components of a community, i.e., trophic webs. According to the environment, the trophic web may be more simple or complex, e.g., with more connections and interactions between components or with greater

In these communities, whether they are subjected to fumigation or the biocides that enter the physical environment with runoff caused by rain, there will be species that are more sensitive than others, and these pollutants can make these species disappear or decrease their numbers extensively. This alteration will also be reflected in species that use this directly affected species as food, leading to increased competition among predators for fewer prey species. In this way, a decrease in diversity and a simplification of the system

In addition, all community members are in contact with the biocide, which may accumulate in organisms. When predators eat contaminated prey the toxic conditions of the biocides from the lower elements of the food chain are transferred to the other trophic levels of the

**6. Relationships between the external medium and an animal's body** 

eggs, or indirectly the reduction of average adult size.

or lesser possibility of prey choice by top members.

abdomen.

of the species.

occurs.

chain, magnifying their effects.

energetic resources, with several detrimental results for survival, growth, gonad development and reproduction (Saravana Bhavan & Geraldine, 1997).

The coordination of movements is also important in behaviours, such as territorial defence, courtship, mating and copulation. Decapod crustaceans, like many others animal species, have a courtship routine that is more or less complex, depending on the species. Mate selection is related to size and previous learning, and some crab species have a kind of "aggressive" courtship during which the male subjugates to the female (Fig. 7).

Agonistic behaviour is common in decapods, especially in crabs, and it is characterised by a series of coordinated movements that lead disputes in which the animals involved are at risk of serious injuries, loss of pereiopods and/or chelae or death of during combat. The more common resources involved in the disputes include shelters, mates and/or food. This behaviour may be affected by side effects of biocides; Williner & Collins (2003) and Collins & Cappello (2006), observed hyperactivity in freshwater crabs and prawns treated with cypermethrin. This hyperactivity capped oxygen consumption, resulting in an obligated hypoactivity during which there was a recovery state with reduced metabolism and lower oxygen consumption. This finding may show that decapods affected by biocides are acerbating the agonistic behaviour in the beginning, with a subsequent negative effect on recuperation. Reproductive behaviour may also be affected. Palaemonid males court females by swimming, chasing after them until they successfully place a piece of spermatophore on the female's abdomen, and cypermethrin produces erratic movements in *Palaemonetes argentinus* (Collins & Cappello, 2006). This could affect both courtship and reproduction itself, especially in regard to "freezing" of the spermatophore, as this requires coordination and precision. It is also possible that a female would find "defective" males under the influence of toxic and remove their sperm packages to obtain offspring with higher fitness or more viable eggs. It has been found that the effect of stress on egg masses affects the viability of these eggs (Siegel & Wenner, 1984). Stress may also disrupt or alter the chemical communication of these animals, as studies show that in many crustaceans, this type of communication occurs, permitting these animals to determine states of dominance. It is also known that during courtship, the chemical perception needed to recognise the state of female receptivity may also be disrupted by the action of biocides. In addition, in relation to energy, oxygen consumption increase as a result of biocide action causing hyperactivity, reduces the energy available for reproduction, either reducing the number of eggs or the effectiveness of the fertility of eggs (Siegel & Wenner, 1984), or in relation to the behaviour during parental care (Fig. 7). Moreover, shrimp in estuaries, such as penaeid shrimp, when exposed to biocides, exhibit decreases in the percentages of proteins as energy resources (Galindo Reyes et al., 1996). This alteration in energy storage could affect animals not only directly but the energy available for reproduction. Huang & Chen (2004) show that endocrine abnormalities were related to levels of testosterone and vitellogenin in *Neocaridina denticulata* treated with toxic. These abnormalities could affect the reproductive behaviour and gonadal development of these shrimp. It is known that female crabs, particularly freshwater crabs, incubate the eggs in their abdomens until hatching, and in some cases keep their offspring alive for some time after hatching, requiring sufficient energy to do so (Senkman, unpublished data). The effects of biocides may provoke the death of eggs and juveniles and the development of abnormal juvenile behaviour caused by stress. During embryonic development, many crustacean females move their eggs with opening and closing movements of the abdomen in rhythm, and their pleopods are used to remove

energetic resources, with several detrimental results for survival, growth, gonad

The coordination of movements is also important in behaviours, such as territorial defence, courtship, mating and copulation. Decapod crustaceans, like many others animal species, have a courtship routine that is more or less complex, depending on the species. Mate selection is related to size and previous learning, and some crab species have a kind of

Agonistic behaviour is common in decapods, especially in crabs, and it is characterised by a series of coordinated movements that lead disputes in which the animals involved are at risk of serious injuries, loss of pereiopods and/or chelae or death of during combat. The more common resources involved in the disputes include shelters, mates and/or food. This behaviour may be affected by side effects of biocides; Williner & Collins (2003) and Collins & Cappello (2006), observed hyperactivity in freshwater crabs and prawns treated with cypermethrin. This hyperactivity capped oxygen consumption, resulting in an obligated hypoactivity during which there was a recovery state with reduced metabolism and lower oxygen consumption. This finding may show that decapods affected by biocides are acerbating the agonistic behaviour in the beginning, with a subsequent negative effect on recuperation. Reproductive behaviour may also be affected. Palaemonid males court females by swimming, chasing after them until they successfully place a piece of spermatophore on the female's abdomen, and cypermethrin produces erratic movements in *Palaemonetes argentinus* (Collins & Cappello, 2006). This could affect both courtship and reproduction itself, especially in regard to "freezing" of the spermatophore, as this requires coordination and precision. It is also possible that a female would find "defective" males under the influence of toxic and remove their sperm packages to obtain offspring with higher fitness or more viable eggs. It has been found that the effect of stress on egg masses affects the viability of these eggs (Siegel & Wenner, 1984). Stress may also disrupt or alter the chemical communication of these animals, as studies show that in many crustaceans, this type of communication occurs, permitting these animals to determine states of dominance. It is also known that during courtship, the chemical perception needed to recognise the state of female receptivity may also be disrupted by the action of biocides. In addition, in relation to energy, oxygen consumption increase as a result of biocide action causing hyperactivity, reduces the energy available for reproduction, either reducing the number of eggs or the effectiveness of the fertility of eggs (Siegel & Wenner, 1984), or in relation to the behaviour during parental care (Fig. 7). Moreover, shrimp in estuaries, such as penaeid shrimp, when exposed to biocides, exhibit decreases in the percentages of proteins as energy resources (Galindo Reyes et al., 1996). This alteration in energy storage could affect animals not only directly but the energy available for reproduction. Huang & Chen (2004) show that endocrine abnormalities were related to levels of testosterone and vitellogenin in *Neocaridina denticulata* treated with toxic. These abnormalities could affect the reproductive behaviour and gonadal development of these shrimp. It is known that female crabs, particularly freshwater crabs, incubate the eggs in their abdomens until hatching, and in some cases keep their offspring alive for some time after hatching, requiring sufficient energy to do so (Senkman, unpublished data). The effects of biocides may provoke the death of eggs and juveniles and the development of abnormal juvenile behaviour caused by stress. During embryonic development, many crustacean females move their eggs with opening and closing movements of the abdomen in rhythm, and their pleopods are used to remove

development and reproduction (Saravana Bhavan & Geraldine, 1997).

"aggressive" courtship during which the male subjugates to the female (Fig. 7).

bad eggs or foreign particles or microorganisms entering via the same motions for the abdomen.

Fig. 7. Different effects that can occur when the animals are expose to biocide in relationship to oxygen consumption, activities, movements, and reproduction. All these affect the fitness of the species.

Biocides are known to affect moulting events in some decapod crustaceans, affecting their growth and keeping many adult individuals in sizes below the average body size of conspecifics. It is estimated that the size of individuals is an important factor in mate choice, as there is a direct relationship in many crustaceans between adult size and the number of eggs a female is capable of carrying, so the effect of biocides may include the number of eggs, or indirectly the reduction of average adult size.
