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Behaviors of the Red Swamp Crayfish (Procambarus Clarkii)

Lydia Roush
Three crayfish of varying size and color were captured and examined in a fish tank for 10 hours. Aggressive, subordinate, feeding, and cleaning behaviors were recorded for each crayfish. Crayfish 1 was found to be the largest and most aggressive individual. Crayfish 2 attempted aggressive behaviors with Crayfish 1 and Crayfish 3, and ate the most food. Crayfish 3, the smallest crayfish, had the most recorded behaviors due to its need to avoid the aggressive behaviors of Crayfish 1 and Crayfish 2.
Crayfish are small crustaceans that reside in freshwater habitats (Olden 2009). Their anatomy is strikingly similar to marine lobsters’, their closely related cousins. Crayfish breath using gills, and are good ecological indicators of water quality. Most crayfish are rather delicate, and cannot survive polluted, dry, or saline situations. However, the red swap crayfish is incredibly robust for its species, and has the capacity to tolerate undesirable habitats and environments. This species can easily be found in calm, fresh waters including ponds, slow streams, and rasacas.
The red swamp crayfish is easily identifiable (Olden 2009). Its long, slender claws, bright red color, and knobby carapace separate it from other common freshwater crustaceans. The Turkish crayfish is almost anatomically identical to the red swamp crayfish, however the Turkish crayfish remains a deep brown, while the red swamp crayfish is colored a brilliant red (HarlioÄŸlu 2004). While invasive to many European countries, the Turkish crayfish has not been introduced to the United States, and therefore should not be found in any of her freshwater systems.
Native to the Gulf Coast, the red swamp crayfish is an edible delicacy for residents of this area (McClain and Romaire 2004). Louisiana, famous for their exquisite creole cuisine, realized the economic potential of this species and began farming red swamp crayfish for human consumption. Other states followed in suit, and the red swamp crayfish was introduced to freshwater systems across the United States. While ecologically benign in Gulf States, the red swamp crayfish has become a detrimental problem in states like Washington and Ohio.
Red swamp crayfish are sensory organisms that use their bodies to feel and taste their surroundings (Turner et al. 1999, Zulandt et al. 1999). Every movement is coordinated; and legs, antennae, claws, eyes, and tail are all directed in a way that optimizes survival (Hughes and Wiersma 1960). These crayfish can expend little energy perched on a rock filter-feeding, their slender legs and v-shaped feet pick through small stones in search of food, their large claws act as both a balancing mechanism and superior weapons. Both sets of antennae are constantly searching for food, and instantly recognize when food has entered the water (Zulandt et al. 1999).
Juvenile crayfish establish hierarchies amongst themselves, and adult crayfish are able to recognize individuals who have acted aggressively towards them in previous encounters (Bergman and Moore 2003, Issa et al. 1999, Keller and Moore 2000, Zucker 1971, Daws et al. 2001). There is a highly social and ranked culture among crayfish, whose establishment is founded on strength and gusto.
The following hypotheses were derived from the available literature: 1.) Crayfish will possess different aggressive/retreating behaviors based on relative size/color. 2.) Crayfish will exhibit a “pecking order.” 3.) Regardless of size, crayfish will eat and clean the same amount. These hypotheses will be tested using the following methods.
Materials and Methods
Aggressive, subordinate, feeding, and cleaning behaviors were examined for three crayfish of varying size and color. Crayfish were obtained from a rasaca and placed in an aquarium. The aquarium was equally lit on both sides by two lamps (Figure 1). Crayfish were allowed to adjust to the aquarium for a week, and allowed to adjust to the light for a minimum of two hours before observations began. Crayfish were viewed for a total of ten hours. Behaviors were analyzed continuously for 1-2 hour periods at a time.
Aggressive behavior was initiated when a crayfish’s body would become erect, raise its claws above its head, and move them in a sweeping motion. Culmination of aggressive behavior occurred when one crayfish would attack an opposing crayfish. Attacks consisted of pinching, ramming, and climbing on the foe. Subordinate behavior occurred when an aggressor approached and foe, and the foe retreated. Two types of retreat were counted: walking or running away, or swimming backwards in a projectile fashion. Crayfish were fed chicken or turkey in excess once a day. Each return to the feed was counted as a new feeding behavior. Cleaning consisted of the crayfish rubbing their legs and claws across their carapace, legs, claws, eyes, and antennae. Behaviors were considered stopped when the crayfish ceased preforming them. Behaviors were considered new and tallied when crayfish started them after previously exhibiting a different behavior (usually sitting).
Crayfish 1, the largest, more opaque crayfish, spent 38.5% of the observation time attacking Crayfish 2 or Crayfish 3, 14% of the observation time eating, and 47.5% of the observation time cleaning (Figure 2). Crayfish 1 never exhibited any avoidance behaviors.
Crayfish 2, the medium sized, most brightly colored crayfish, spent 21% of its time attacking Crayfish 1 and Crayfish 3, 7% of time avoiding conflict by walking, 9% of its time avoiding conflict by swimming backwards, 33% of its time feeding, and 30% of its time cleaning (Figure 3).
Crayfish 3, the smallest, blue crayfish, didn’t attack either Crayfish 1 or Crayfish 2, spent 59% of observation time avoiding conflict by walking, 27% of observation time avoiding conflict by swimming backwards, 10% of observation time feeding, and 4% of observation time cleaning. Crayfish 3 also displayed the most behaviors, and was the most active crayfish in the tank, mainly due to avoiding the other two crayfish (Figure 4).
Crayfish did exhibit a pecking order that appeared to be based on size. The largest crayfish, Crayfish 1, had the highest rate of attack. The smallest crayfish, Crayfish 3, had the highest rate of avoidance, causing him to have the highest number of documented behaviors in the tank. Crayfish, however, did not eat and clean the same amount. Crayfish 1 spent the most time cleaning, while Crayfish 2 spent the most time eating. Crayfish 3 did very little of these activities. These results hint that size may be a key component to crawdad behavior. Hormones, body mass, or experience may regulate behaviors at different stages of development, and more precise measurement and implementation may help distinguish any potential influences. It may also be valuable to attempt to mate and raise crayfish in isolation to decipher which behaviors may be learned and which are innate. Cross-fostering experiments between crayfish species may also help identify species-specific behaviors.
A more detailed study of individual behaviors is necessary for this species. Each behavior is so complex and multi-faceted that careful examination of only leg use, feeding, antennae, etc. should be conducted. The initial behavioral examinations of this study were far too broad, and although this study showed potential trends in crayfish behavior, a more detailed study will help tease these out.
During this study, crayfish also presented scototaxis-like behaviors. When both lamps were turned on, illuminating the fish tank, crayfish became tense and attempted to avoid the light and retreat into darker areas. Examination of this species in the terror tanks would be interesting, and may help to explain additional behavioral tendencies.
Literature Cited
Bergman, D.A., and P.A. Moore. 2003. Field observations of intraspecific agonistic behavior of two crayfish species, Orconectes rusticus and Orconectes virilis, in different habitats. Biology Bulletin 205: 26-35.
Daws, A.G., J. Grills, K. Konzen, and P.A. Moore. 2001. Previous experineces alter the outcome of aggressive interactions between males in the crayfish, Procambarus clarkii. Marine and Freshwater Behaviour and Physiology 35: 139-148.
Edwards, D.H., W.J. Heitler, and F.B. Krasne. 1999. Fifty years of a command neuron: the neurobiology of escape behavior in the crayfish. Trends in Neuroscience 22: 153-161.
HarlioÄŸlu, M.M. 2004. The present situation of freshwater crayfish, Astacus leptodactylus (Eschscholtz, 1823) in Turkey. Aquaculture 230: 181-187.
Hughes, G.M. and C.A.G. Wiersma. 1960. The co-ordination of swimmeret movement in the crayfish, Procambarus clarkii (Girard). Journal of Exploratory Biology 37: 657-672.
Issa, F.A., D.J. Adams, and D.H. Edwards. 1999. Dominance hierarchy formation in the juvenile crayfish Procambarus clarkii. The Journal of Experimental Biology 202: 3497-3506.
Keller, T.A., and P.A. Moore. 2000. Context-specific behavior: crayfish size influences crayfish-fish interactions. Journal of North American Benthological Society 19: 344-351.
Kennedy, D, W.H. Evoy, and J.T. Hanawalt. 1966. Release of coordinated behavior in crayfish by simple central neurons. Science 154: 917-919.
McClain, W.R., and R.P. Romaire. 2004. Crawfish culture: A Louisiana aquaculture success story. World Aquaculture 35: 31-35.
Olden, J.D. 2009. Brief guide to crayfish identification in the Pacific Northwest. University of Washington.
Turner, A.M., S.A. Fetterolf, and R.J. Bernot. 1999. Predator identity and consumer behavior: differential effects of fish and crayfish on the habitat use of a freshwater snail. Oecologia 118: 242-247.
Zucker, R.S. 1971. Crayfish escape behavior and central synapses. II. Physoological mechanisms underlying behavioral habituation.
Zulandt Schneider, R.A., R.W.S. Schneider, and P.A. Moore. 1999. Recognition of dominance status in the red swamp crayfish, Procambarus clarkii. Journal of Chemical Ecology 25: 781-795.
Figure 1. Diagram of experimental design. Three red swamp crayfish of varying color and size were place in an aquarium with two lamps on either side, providing equal lighting within the aquarium.

Figure 2. Pie chart of prominent behaviors exhibited by Crayfish 1 during the 10-hour observation period.
Figure 3. Pie chart of prominent behaviors exhibited by Crayfish 2 during the 10-hour observation period.

Figure 4. Pie chart of prominent behaviors exhibited by Crayfish 3 during the 10-hour observation period.

Sources of Particulate Matter: An Overview

A brief summary of the sources of particulate matter (PM) will be presented. The will be a brief overview of ‘particulate matter’ in regard to sources, history and additionally there will informative discussion such as PM levels as set by authoritative regulations.
Discussion will include the different sources of particulate matter and with specific attention to emission vehicle fuel sources, since they are the largest contributors of PM in the environment (1, 2). Lastly, A brief discussion of the different metals found in ambient PM will be discussed and their health effects, these include copper, zinc and iron (4).
There are several sources from which particulate matter finds itself into the environment and ultimate humans, inhalation is the typical mechanism in which PM enters the body and is then absorbed during gas-exchange in the lungs (3). Therefore there will be a brief summary of the health effects of particulate matter (PM).
Discussion – Overview and a brief history Particulate matter (PM) is a world wide problem; one of the major sources of PM is vehicle traffic and as a result it has been the subject of various epidemiological studies (1). Studies on PM have shown that particle size plays a key role on the adverse effects cause by PM concentrations (1). For example, studies have shown that children living near higher have larger risk of developing asthma and allergies from dust (2). Studies have also shown that the density of vehicles traffic does not account for differences in PM toxicity between similar communities; it therefore indicates that particle chemistry also plays a role in health effects (1, 2).
Particulate matter is typically composed of organic and inorganic materials and source are both natural and anthropogenic (1). Thus particulate matter can be divided in to two groups, Primary PM and Secondary PM: Primary PM can be the direct result of fossil fuel combustion, natural wood combustion, volcanoes, soil dust, pollen, smelting, mining and milling process (3). Secondary PM are created by chemical reaction of primary PM such as SO2, nitrogen oxides (NOx) and Ammonia (NH3), for example the formation of ammonium nitrate (NH4NO3) (3). However, Volcanoes, wildfires and other can contribute to both primary and secondary PM (3). Other natural sources include volatile organic compounds (VOC) from trees, vegetation and emission of gases such as sulfur from wet lands (3, 8).
Particle size pertaining to both primary and secondary PM can be subdivided into size fractions: Large particles are > 30µm and smaller particles are divided into PM2.5 (<2.5 µm) and PM10 (<10 µm) and lastly there are ultrafine particles of ( 30µm) since these are only suspended for short periods of time (1) (see figure 1 (6. PM of sizes smaller then 1 µm are consider to cause the most adverse effect since these can penetrate the pulmonary alveoli (part of the respiratory system for gas-exchange in the lungs) (1). Although particle size is a factor in the penetration capabilities of PM into the alveoli, another factor is the chemical composition of the PM (1). Some of the pollutants that are part of PM composition include heavy metals, polycyclic aromatic hydrocarbons (PAHs), and acid aerosols among others (1).
PM is considered one of the 6 criteria pollutants by the Environmental Protection agency (7). Additionally, The U.S. Clean Air Act and set by the EPA has established that the primary standard for the protection of human heath is PM10 at 150µg/m3 (24 hrs) and PM2.5 at 35µg/m3 (24 hrs) and 15µg/m3 (Annual) (7). The EPA recognizes that there is no threshold for the adverse health effects from long term exposure to PM10 therefore the annual PM10 standard has not been accepted (7).
In Canada, Air Quality objectives where first established in the 1970s and revised in 1980 under the knowledge that PM could cause adverse effect only in severe pollution loads (8, 9). However, it was not until the 1990s that serious health effects where identified for low levels of fine particles such as PM2.5 and PM10 (8, 9). As result, PM10 and PM2.5 where consider to be toxic and where included in the Canadian Environmental protection Act (CEPA, 1999), the Canada-Wide Standard (CWS) goal (set in 2000) for Canada ambient air quality are PM2.5 < 30µg/m3 (24 hrs) by 2010 (9) (see figure 2 and table 1 for CWS across Canada). Additionally, in 2003 the secondary pollutants forms of PM2.5 such as sodium oxides, nitrogen oxides and volatile organic compounds where consider to be toxic and added to CEPA (7). Lastly, Canada and the United States joined together to corporate in the reduction of PM under the Canada-United States Border Air Quality
Strategy (1991) (12).
As mention above, urban traffic is one of the major sources of PM; some studies in Copenhagen found that traffic accounts for about 13% for PM10 and 35% to 50% of PM2.5 (1). Most of vehicles today run on combustion engines using fossil fuel such as gasoline and diesel (diesel engines are known to contribute significantly in greater quantities to PM concentrations then gasoline engines) (1). Other sources of PM from vehicle traffic include brake pad wear, tire wear, and by physical resuspension of dust (1).
One of the challenges of studies on PM is to identify the source of the PM (1). Researches know that PAH and some of its derivatives are created via combustion of fossil fuel (1, 2). It is a selection of PAH derivates together with other organics chemicals such as hopanes and steranes (from lube oil) that are used in the identification of PM from traffic sources (1,2). Dynamometer test which is used for the measurement of HP and torque of engines provide a good control environment to adequately measure PM from engines, since exhaust lines are attached to collection and detection instruments (2). The only difficulty or limitation in dynamometer test is that real life environment of urban traffic has other factors that contribute to the overall PM concentrations, these include the age of the vehicle, maintenance history, size of engines (expensive to test every size engine), atmospheric interactions/reactions with other chemicals and other dust contributors like brakes dust etc (2).
Vehicle Emission a source of PM – Los Angeles, CA study Because of the challenges presented for vehicle emissions there have been studies conduction in traffic tunnels, these present researchers with unique control environment (2). The only limitation of tunnel test is that it does not account for cold start emission since it only measures the vehicles through the driving conditions of the tunnel, secondly the tunnel may present different conditions than ambient conditions such as dilution with air, temperature and humidity (2).
Gas chromatography-mass spectrometry (GC-MS)) is the preferred method for the detection of atmospheric PM in the environment (2). The methods for identifying primary PM from gasoline and diesel engines has been to identify for example hapanes