Comp. Biochem. Physiol. Vol. 119A, No. 1, pp. 263–269, 1998 ISSN 1095-6433/98/$19.00Copyright 1998 Elsevier Science Inc. All rights reserved. PII S1095-6433(97)00413-3

Effect of Variation in Photoperiod and Light Intensityon Oxygen Consumption, Lactate Concentration and

Behavior in Crayfish Procambarus clarkii andProcambarus digueti

Marıa Luisa Fanjul-Moles,* Theresa Bosques-Tistler,* Julio Prieto-Sagredo,*Oscar Castanon-Cervantes* and Leonor Fernandez-Rivera-Rıo†

*L. Neurofisiologia Comparada, Depto. Biologia, Fac. Ciencias, UNAM, Coyoacan, Mexico

and †Depto. Bioquimica, Fac. Medicina, UNAM, Coyoacan, Mexico

ABSTRACT. The effects of light intensity and duration on metabolic and behavioral parameters of two speciesof crayfish, Procambarus clarkii and Procambarus digueti, were studied. Sixty animals of each species were submittedto high irradiance conditions of two different photoperiod lengths, one normal light/dark (LD) 12 :12 and oneextreme LD 20:4 for 2 weeks. Hemolymph, lactate and oxygen consumption were determined throughout theexperimental period. Simultaneously in 18 additional animals of each species, motor activity was individuallyrecorded under the same control and experimental conditions. Both species showed a decrease in oxygen uptakeand an increase in hemolymph lactate concentration. The statistical significance of this finding was higher forLD 20 :4. This extreme condition evoked a significant decrease of motor activity in P. clarkii and a high mortalityrate in P. digueti. P. digueti did not survive after the experiment, whereas P. clarkii survived and adapted to thelaboratory conditions. Changes in metabolic and behavioral parameters could indicate different adaptation abili-ties in these species. comp biochem physiol 119A;1:263–269, 1998. 1998 Elsevier Science Inc.

KEY WORDS. Crayfish, photoperiod, light, intensity, stress, oxygen, consumption, lactate, Procambarus clarkii,Procambarus digueti

INTRODUCTION tion. The presence or absence of open waters seems to beequally important. The metabolic rate of the crayfish seems

Light as an environmental parameter has been given littleto be affected by changes in all of these conditions (27),

consideration as a stressor affecting animal function ratebut light’s influence on metabolic parameters of decapods

and, hence, limiting distribution (19). The alteration in-has been controversial. Changes have been reported in the

duced by extreme photoperiods or light intensities on theoxygen consumption of intertidal crabs submitted to differ-

biological rhythms of diverse animals is well known (2) andent photoperiod lengths (4), whereas other authors reported

suggests the importance of this environmental parameter.a lack of effect of this variable on the metabolic rate ofBoth energy metabolism and biological rhythms are impor-crayfish Orconectes nais (20). However, crayfish activity is

tant characteristics of biological organization; some authorsregulated accordingly by the presence or absence of light

have indicated the relevance of light intensity in compara-(17), and moult and reproduction seem to be photoperiodi-

tive studies on metabolic rate (1). The objective of thiscally regulated (24).

study was to test the effect of light intensity and durationIn this study artificial light was used as a selective tool

on metabolic and behavioral parameters in crayfish, an or-to perturb two species of crayfish evolved in, and adapted

ganism in which metabolic differences could be correlatedto, several environments at different latitudes to investigate

with differences in habitats at different latitudes as reportedthe physiological dynamics that could be involved in de-

for other species (26). Under natural conditions, animalstermining these animal’s distribution and adaptation pat-

are submitted to many ecological variations, for example,terns. Procambarus clarkii is a species introduced into Mexico

differences in temperature and dissolved oxygen concentra-from regions of high latitudes. It is an invasive species ofboth aerobic and anaerobic environments and is known toAddress reprint requests to: M. L. Fanjul-Moles, L. Neurofisiologıa Compa-

rada, Depto. Biologia, Fac. Ciencias, UNAM, Ap. Postal 70-371, Coyoa- replace endemic species (12). Procambarus digueti is endemiccan, C.P. 04510, D.F., Mexico. Tel. (525) 622-4830; Fax (525) 622-4828; to the equatorial and tropical regions of the central part ofE-mail: jps@hp.fciencias.unam.mx or mlfm@hp.fciencias.unam.mx.

Mexico and lives in shallow and well-oxygenated waters.Received 13 November 1996; revised 18 February 1997; accepted 26February 1997. Animals of both species were submitted for 2 weeks to two

264 M. L. Fanjul-Moles et al.

cycles of different photoperiods, one normal and one ex- plastic tubes to be used as shelters. The aquaria were pro-vided with continuous aeration to obtain the same oxygentreme, at the same high irradiance. Two parameters, both

dependent on metabolism, oxygen uptake and hemolymph concentration as in the acclimatation aquaria, at constantpH and temperature conditions equal to those indicatedlactate concentration, were determined. Additionally, a be-

havioral parameter related to metabolism, locomotor activ- above. Photoperiod was provided by neon lamps turned onby a timer at 07:00, light QSI was calibrated with a photora-ity was also studied. The results indicate that both species

react to normal and extreme high irradiance photoperiods diometer provided with a spherical submarine sensor (LicorModels. LI 189 LI 193SA, Lincoln, Nebraska). In a secondby decreasing their oxygen consumption and increasing

hemolymph lactate concentration, as well as diminishing experiment, 18 animals of each species were used to recordindividual locomotor activity during the 2 weeks under thethe locomotor activity.same control and experimental conditions: high irradiance,LD 12:12 and high irradiance, LD 20:4.

MATERIAL AND METHODSAnimals and Housing

Lactate DeterminationTwo groups of adult male and female crayfish, P. clarkii (Gi-rard, 1852) (n 5 78) and P. digueti (Ortmann, 1905) (n 5 Animals were anesthetized with ice for 10 min always at

the same time of day (09:00) to avoid circadian variations,78) in intermoult stage were used. Organisms of homoge-neous size and weight were chosen (P. clarkii, weight 36.6 and 20 µl of hemolymph was extracted from the ventral

region of pleon. Perchloric acid extracts were prepared by6 1.96 g: P. digueti, weight 10.25 6 0.55g). P. clarkii werecollected from Northern Mexico at a latitude of 28°N and adding 60 µl of 1.42 M perchloric acid to 20 µl of hemo-

lymph followed by shaking and centrifuging in an Eppen-P. digueti from the central part of Mexico at a latitude of19°N. Before the experiments, animals were acclimated to dorf Model 5415C microcentrifuge. Extracts were kept on

an ice bath until lactate determination was performedlaboratory conditions for 3 months in aquaria placed undera light/dark (LD) 12:12 cycle using a white light quantum (about 20 min later). Lactate concentration was measured

as described elsewhere (7), in 1 ml spectrophotometer cellsscalar irradiance (QSI) of 0.6 µM/sec ⋅m2 during pho-tophase, temperature of 20°C, pH 7.9, O2 concentration of in which 10 µl of hemolymph extract were mixed with 250

µl 0.4 M triethanolamine, 50 µl 1.0 M pyruvic acid, 10 µl5.7 mg/l. Two types of experiments were performed. In thefirst, hemolymph lactate concentration and oxygen con- 0.005 M NADH, 37 µl EDTA (100 mg/ml) and 643 µl de-

ionized water, final pH 7.4. Reaction was started by add-sumption were determined, and in the second, locomotoractivity was individually recorded. ing 5 µl of rabbit muscle l-lactic dehydrogenase (Sigma)

diluted 1:10. Reaction was followed in a Zeiss spectropho-Before the first experiment, 10 animals of each specieswere randomly chosen to monitor oxygen consumption and tometer at a wavelength of 362 nm until measurements pre-

sented no more changes (about 20 min) at room tempera-10 animals of each species were randomly chosen to samplelactate. These animals were reintroduced to the animal ture. Calculations were made and data were refered in mol

lactate/l hemolymph. Experimental results were comparedpool. The animals were divided according to their species,in two blocks consisting of 60 animals from each species. with those obtained from the control animals. Because of

inequality of data variance, statistical analysis was per-Each block was randomly divided into two groups, one todetermine lactate concentration and one to determine oxy- formed by means of the Kolmogorov-Smirnov test.gen uptake. Each group was divided into three batches: con-trol, experimental condition 1 (LD 12:12) and experimen-

Oxygen Determinationtal condition 2 (LD 20:4) of 10 animals each (n 5 60 foreach species). Control animals were submitted to LD 12: Oxygen consumption was determined individually at the

same time of day (09:00) in respiration chambers con-12, 0.6 µM/sec ⋅m2 during photophase. Experimental condi-tion 1 animals were submitted to LD 12:12 cycles with a structed in our laboratory consisting of an acrylic tank of

4.2 l capacity with well-aerated water. The chambers canQSI of 34.5 µM/sec⋅m2 in photophase, whereas experimen-tal condition 2 animals were submitted to LD 20:4 with a be sealed hermetically with a lid with a port for allowing

the introduction of an oxygen electrode (YSI-51B, YellowQSI of 34.5 µM/sec⋅m2 in photophase. These conditionswere maintained for 2 weeks. Springs, Ohio); inflow and outflow tubes allow quick en-

trance and removal of water. Each animal was placed in theAt the end of the first and second week, one batch ofeach species and condition (control, LD 12:12 and LD 20: open chamber at least 2 hr before the determination (27).

The respiration chamber had a thermometer and a platform4) was sampled to determine oxygen uptake and the otherthree batches were sampled for lactate concentration. To to separate the organism from the magnetic stirrer, on the

bottom. Oxygen consumption was determined for 30 minavoid stress caused by overcrowding, animals were separatedin groups of five for each of the species in aquaria of 60 l, after closing the chamber. Sterilized and aerated tap water

was used to avoid contamination with microorganisms inprovided with biological filters and some polyvisol chloride

Effect of Photoperiod and Light Intensity 265

all the experiments. Control measurements were performed 2345 m, latitude 27°45′N), and these animals are submittedat an intensity range of 0.48 µM/sec ⋅m2 at dawn to 45 µM/in a chamber with the same conditions but lacking animals.

Oxygen consumption by the animal was calculated by sub- sec⋅m2 at noon in natural conditions. P. digueti prefersponds, lakes and streams with open water; the locationstracting control from experimental measurements. Oxygen

meters and probes were operated in a stable temperature from which P. digueti was obtained were small flowingstreams with an average depth of 0.5–1.5 m. Some streamsroom, maintaining the appropriate temperature and light

conditions. All experiments started on a different day of the were flanked by vegetation, whereas others were nearly de-void of any flora (Fanjul-Moles et al., personal observations).week for us to make the determination at the same time of

day to avoid circadian variations. Experimental results were To fix experimental light intensity, we made field deter-minations on the P. digueti’s habitat (Zamora, Michoacan,compared with those obtained from the control animals.

Statistical analysis of data was performed by one-way Mexico, altitude, 1575 m; latitude, 19°98′N) at differenthours of the day. Light QSI was measured by means of aANOVA followed by a Scheffe contrast test.spherical submarine sensor (Licor Models LI 189 and LI193S) submerged at 0.7 m under shadowy and sunny areas

Motor Activity during an uncloudy summer day. The intensity ranged from0.13 µM/sec⋅m2 at dawn and dusk to 39.5 µM/sec⋅m2 atLocomotor activity was determined on the 18 remaining

animals from each species. Animals were placed individu- noon. Hence, the experimental high irradiance was fixed to34.5 µM/sec ⋅m2, assuming this to be the maximal irradianceally in recording aquaria under the same control and experi-

mental photoperiods (LD 12:12 and LD 20:4) during 2 at which P. digueti could be submitted under natural condi-tions (we were assuming P. digueti as the more sensitive spe-weeks. All experiments were started at noon (i.e., animals

were taken to the recording aquaria during the photophase cies). Low control irradiance was fixed to 0.6 µM/sec⋅m2,irradiance at which all the crayfish are maintained duringof the LD cycle). Each aquarium, made of black acrylic, was

provided with an array of photodiode-photocell couplers in acclimatation in our laboratory. Experimental photoperiodswere LD 12:12 and LD 20:4, comparing these values withwhich the emission wavelength of the diodes was 900 nm.

Movement of the animal along the aquarium interrupted the natural summer LD 13:11 in central Mexico to the 16:8of the northern latitudes; 20 hr of light must be an extremethe light beam so that the sensor sent a signal to a series

of analogue circuits that, in turn, emitted a voltage signal photoperiod for both species.to a computer, where the signal was accumulated in 20-minbins. Food was placed daily on the bottom of the aquarium,

RESULTSso that animals ate ad libitum. Each aquarium was continu-ously aerated. Photoperiod was provided by neon lamps, Table 1 shows differences in hemolymph lactate concentra-

tion between P. clarkii and P. digueti under control and ex-placed at 60 cm distance and calibrated at a light intensityof 0.6 µM/sec ⋅m2 for the control animals (six of each spe- perimental conditions. Neither P. clarkii nor P. digueti

showed a statistically significant difference among the con-cies) and 34.5 µM/sec⋅m2 for the experimental animals.Motor activity was continuously recorded for 2 weeks and trol values during the experiment. The control values are

similar to those reported for other Decapoda (18); hemo-analyzed by calculating percentage of activity, considering100% of activity as the total recording time (1 week 5 lymph lactate concentration is about four times higher in

P. clarkii than in P. digueti. P. clarkii showed a significant10,080 min). Data obtained were analyzed by comparingthe experimental data (LD 12:12 and LD 20:4) with the increase after a week under both conditions, LD 12:12 and

LD 20:4; this increase is even higher (about 100 times thepercentage of activity recorded under control conditions.Statistical tests used included ANOVA, followed by Scheffe value observed in control animals) after 2 weeks in LD 20:

4. Statistical analysis shows significant differences amongand Tukey HSD contrast tests. Yates correction was usedto replace the lost data due to mortality. control and experimental conditions at 1 and 2 weeks

(P , 0.001).P. digueti increased hemolymph lactate (about 317 times

Assessment of Light Parameters the control values) after 1 week of LD 12:12. This increasepersisted in the second week measurement. Under LD 20:The crayfish is usually a nocturnal animal, the highest lumi-

nosity to which it is submitted occurring at dawn and dusk, 4 after the first week, a very high increase, 49.0 µmol/ml,was observed; however, this value suddenly diminished toalthough during the breeding season some species can be

exposed to daylight (10). P. clarkii has been found in habi- 6.7 µmol/ml in the second week measurement. Statisticalanalysis revealed significant differences among the controltats such as muddy ponds and slow muddy streams and is

abundant in seasonal swamps and marshy waters (12). This groups and the two experimental conditions at 1 and 2weeks (P , 0.001).species is a burrower and chimney-builder and is normally

distributed from 59° to 28°N (12). P. clarkii was collected Control values for both species showed interspecific dif-ferences in oxygen consumption. Experimental conditionsin a location near Chihuahua, Chihuahua, Mexico (altitude

266 M. L. Fanjul-Moles et al.

TABLE 1. Oxygen consumption as a function of weight and hemolymph lactate concentration of Procambarus clarkii andProcambarus digueti

P. clarkii* P. digueti†

Condition Condition Condition ConditionTime (wks) Control LD 12:12 LD 20:4 Control LD 12:12 LD 20:4

Oxygen consumption (µmol/g/hr) 6.467 6 0.002‡ 17.07 6 0.032‡1 6.8 6 1.15 2.54 6 0.16 3.08 6 0.16 22.24 6 0.88 15.22 6 0.69 13.36 6 1.122 6.68 6 0.57 5.24 6 0.32 4.15 6 0.53 21.7 6 1.04 12.4 6 0.6 8.87 6 0.28

Lactate concentration (µmol/ml) 0.207 6 0.009‡ 0.053 6 0.014‡1 0.122 6 0.041 7.53 6 0.23 11.5 6 1.0 0.056 6 0.012 17.8 6 4.72 49.0 6 6.972 0.176 6 0.039 12.5 6 1.45 21.0 6 4.32 0.166 6 0.003 14.3 6 0.2 6.79 6 0.78

Values are means 6 SD.*For oxygen consumption, ANOVA: F 5 17.6, P , 0.001. Scheffe contrast test significant differences (P , 0.05): control 1 week vs experimental

condition 1, 1 and 2 weeks; control 2 weeks vs experimental condition 2, 1 and 2 weeks. For lactate concentrations of both P. clarkii and P. digueti,Kolmogorov-Smirnov test. Significant difference among all the groups, P , 0.001.

†For oxygen consumption, ANOVA: F 5 11.54, P , 0.001. Scheffe contrast test significant differences (P , 0.05): control 1 week vs experimentalcondition 1, at 2 weeks; control 2 weeks vs experimental condition 2, 1 and 2 weeks.

‡Control values before experiment (n 5 10).

of LD 12:12 and LD 20:4 in P. clarkii produced a lower values, as the high standard deviation indicates. All animalsof this species survived the experimental conditions andoxygen uptake in the first week of measurement, which in-

creased in the second week of measurement. Experimental adapted well to laboratory. Figure 2 depicts 16 days of typi-cal locomotor activity recordings of two individual of thisP. digueti showed a marked decrease in oxygen uptake, at

the second week of determination, reaching about half of species submitted to LD 12:12 and LD 20:4. There is aremarkable decrease of activity in the animals submitted tothe observed value in the control condition at the second

week of determination. Statistical tests revealed significant the long photoperiod, although it is the same light QSI.ANOVA analysis showed significant differences among alldifferences (P , 0.05) among control and experimental

groups and between experimental groups (Table 1). the groups (P , 0.01). Tukey HSD contrast test revealedsignificant differences (P , 0.05) among the LD 12:12 1Figure 1 (top) depicts the graphs relating the percentage

of motor activity recorded from P. digueti and the time of week and LD 20.4 1 and 2 week experiments; however, thedifferences were not significant by the Scheffe contrast test.photoperiodic exposure. Control traces depict the mean

percentage of motor activity recorded from six specimens The percentage of surviving animals during the two ex-periments of this study and 1 week after them is shown induring 1 week under LD 12:12 cycles, yielding 39.33% ac-

tivity. This activity increases in the LD 12:12 experimental Fig. 3; P. digueti shows a post-experimental survival of69.23%, whereas P. clarkii survived in all the experimentalcondition to 51.98% during the first week and decreases to

45.68% during the second week. The six animals of this conditions.species, submitted to LD 20:4, showed apparent changes ascompared with the control value, decreasing 17.69% during

DISCUSSIONthe first week. This value represents the average of only fourspecimens; two animals died during this week. This decrease Results obtained from this study indicate that an increase

in light irradiance and in the photoperiod length producewas even more prominent during the second week, duringwhich one of four remaining animals died. The mean motor an increase in hemolymph lactate similar to that produced

by exercise and other factors considered as stressors in deca-activity of the three living animals was 28.16% with a highstandard deviation: 10.2. It must be noted that the other pod Crustacea (14,15,25,29).

High irradiance in both normal and extreme photoperi-animals of this species only survived for 1 week after theexperiment. ANOVA analysis showed P , 0.05. However, ods resulted in increased hemolymph lactate concentration

and a decline in oxygen consumption, but the 20-hr photo-Scheffe and Tukey HSD contrast test showed no significantdifferences among groups. period produced even higher lactate concentration values.

The relation between lactate concentration and oxygenP. clarkii showed no important changes in the percentageof locomotor activity (Fig. 1, bottom) as compared with the consumption throughout the experiment suggests differ-

ences in the physiological dynamics of both species to thiscontrol recordings, neither 1 nor 2 weeks after having beenplaced in a 12-hr photoperiod. However, in the 20-hr pho- luminic stress. P. clarkii is able to maintain high levels of

lactate hemolymph concentration, tending to recover thetoperiod, the activity decreased 19.86% from the controlvalue, remaining unchanged after the second week. The de- oxygen uptake to 50% of the control value at the end of

the experiment. All organisms of this species survived aftercrease in mean activity is accompanied by a dispersion of

Effect of Photoperiod and Light Intensity 267

FIG. 2. Locomotor activity recording of two P. clarkii sub-mitted to LD 12:12 (top) and to LD 20:4 (bottom). See textfor further explanation.

the experiment, acclimatizing afterward to the laboratoryconditions. Conversely, P. digueti, although strongly in-FIG. 1. Relationship between percent changes in locomotorcreasing hemolymph lactate concentrations, seems unableactivity and duration of light irradiance in crayfish P. digueti

(top) and P. clarkii (bottom). Each point corresponds to the to maintain these levels to the end of the experiment, whenaverage of 6 measurements, except for P. digueti at LD 20: a sharp decline in lactate concentration and oxygen uptake4 1 week (n 5 4) and P. digueti at LD 20:4 2 weeks (n 5 occur. The aforementioned could be the cause for post-3). Bars indicate SD. *Significant difference (p , 0.05).

experimental survival rate of this species (69.23%; Fig.3).These results seem to indicate changes in the metabolism

of these species. Hemolymph lactate concentration is agood indicator of anaerobic metabolism, whereas oxygenconsumption is a parameter of the aerobic respiratory rate.The conversion of glucose to lactate in decapod Crustacea

268 M. L. Fanjul-Moles et al.

spiratory and cardiac pumping are controlled by the nervoussystem (28). The current results suggest an effect of lighton the neural and endocrine structures responsible for thecontrol of behavior and metabolic functions.

The metabolic changes, the behavioral findings and thedifferent survival percentages encountered for both speciesindicate different capabilities to adapt to luminic stress. Atlow latitudes, P. clarkii is active during the cold months andinactive during the hot ones; in contrast, at high latitudes,the behavior reverses and dormancy occurs during the win-ter months (12). In P. digueti, no form of dormancy hasbeen reported. In P. clarkii, the encountered changes couldsuggest a shift from aerobic pathways to anaerobic ones in-duced by light, a shift that is accompanied by a decrease inmotor activity. It is interesting to point out that these tworesponses correspond to similar strategies found in some fac-ultatively hibernating or estivating anaerobic animals (9)in which metabolic rates decrease and animals enter into aquiescent period with a marked reduction in motor activity.The different survival abilities shown by these two species

FIG. 3. Percentage of surviving animals of both species, and their physiological changes to the extreme conditionsthroughout experiment and 1 week post-experiment (1PE). of light suggest new experiments.

We thank Fernando Colchero for his help with lactate and oxygen deter-minations, Manuel Miranda-Anaya for his help with the activity record-has been demonstrated by several authors (3,11,18). It hasings and Adolfo Andrade-Cetto for the use of facilities at the stablebeen proposed (6) that lactate is produced via glycolyticenvironment chambers of the Facultad de Ciencias. We thank Mrs.

pathways in the anaerobic reduction of pyruvate, although Ingrid Mascher for her editorial advice. This work was supported inthe routes of elimination or reprocessing are not known part by a grant from PADEP UNAM (003001) and CONACYT

112-PN. We also thank the unknown reviewers for their contribution(13). The results of this study suggest that P. clarkii couldto this work.increase lactate concentration by accelerating anaerobic

glycolysis, replacing aerobic energy production until the re-covery of the oxygen uptake. P. digueti seems unable to do

Referencesit, depending more on aerobic metabolism. 1. Aschoff, J.; Pohl, H. Rhythmic variations in energy metabo-

In general, a positive correlation between variations in lism. Fed. Proc. 2:1541–1552;1970.2. Aschoff, J. Freerunning and entrained circadian rhythms. In:locomotor activity and oxygen consumption has been dem-

Aschoff, J. (ed). Handbook of Behavioral Neurobiology. Bio-onstrated. Circadian rhythms in both of these variableslogical Rhythms, Vol. 4. New York: Plenum Press; 1981:81–have been reported (5,16). In the current study, the deter-93.

minations of the metabolic parameters were done at 09:00 3. Boyland, E. Chemical changes in muscles— Invertebrateand motor activity was recorded continuously. Hence, muscle. Biochem. J. 22:362–376;1928.

4. Dehnel, P.A. Effect of photoperiod on the oxygen consump-causal correlation between these parameters cannot be es-tion of two species of intertidal crabs. Nature 181:1415–1417;tablished.1958.During the first week of recording under LD 12:12 at

5. Fingerman, M. Factors influencing the rate of oxygen con-high intensity, the percentage of activity increased, whereas sumption of the dwarf crawfish Cambarellus-shufeldtii. Tulaneoxygen consumption diminished. In other crustacean spe- Stud. Zool. 3:103–116;1955.

6. Gade, G.; Grieshaber, M.K. Pyruvate reductase catalyzes thecies, hyperactivity, as a transitory response to hypoxia, hasformation of lactate and opines in anaerobic invertebrates.been reported (8). However, during the second week andComp. Biochem. Physiol. 83B:255–272;1986.especially in LD 20:4, both species reduced their locomotor

7. Gutmann, I.; Wahlefeld, A.W. l-(1)-Lactate. Determinationactivity, indicating a reduced energetic expenditure. with lactate dehydrogenase and NAD. In: Bergmeyer, H.U.

In both species, the extreme photoperiod seems to inhibit (ed). Methods of Enzymatic Analysis, Vol. 3. New York: Aca-demic Press Inc.; 1974:1464–1468.motor activity (Figs. 1 and 2). Hyperactivity has been re-

8. Hervant, F.; Mathieu, J.; Garin, D.; Freminet, A. Behavioral,ported in crayfish of the genus Cambarus submitted to eye-ventilatory, and metabolic responses to severe hypoxia andstalk ablation. This hyperactivity can be reverted by a neu-subsequent recovery of the hypogean Niphargus rhenorhoda-

rohumoral factor produced by the same peduncle (21,22). nensis and the epigean Gammarus fossarum (Crustacea: Am-Eyestalk control on metabolic rate has also been demon- phipoda). Physiol. Zool. 68:223–244;1995.

9. Hochachka. P.W.; Guppy, M. Metabolic Arrest and the Con-strated in the crayfish (5,23). In other decapod species, re-

Effect of Photoperiod and Light Intensity 269

trol of Biological Time. Cambridge, MA: Harvard University consumption of Orconectes nais. Comp. Biochem. Physiol.47A:261–270;1974.Press; 1987.

10. Hofmann, J. Die Flusskrebse. Berlin: Verlag; 1971. 21. Roberts, T.W. Evidences that hormonal inhibition of locomo-tion occurs for the crayfish C. virilis. Hagen. Anat. Rec.11. Huggins, A.K. Intermediary metabolism in Carcinus maenas.

Comp. Biochem. Physiol. 18:283–290;1966. 81(Suppl.)46–47;1941.22. Roberts, T.W. Light, eyestalk chemical, and certain other fac-12. Huner, J.V. Procambarus in North America and elsewhere. In:

Holdich, D.M.; Lowery, R.S. (eds). Freshwater Crayfish. Biol- tors as regulator of community activity for the crayfish, Cam-barus virilis. Hagen. Ecol. Monogr. 14:361–385;1944.ogy Management and Exploitation. Portland, OR: Timber

Press; 1988:239–291. 23. Scudamore, H.H. The influence of the sinus glands uponmolting and associated changes in the crayfish. Physiol. Zool.13. Lallier, F.H.; Walsh P.J. Metabolism of isolated hepatopan-

creas cells from the blue crab (Callinectes sapidus) under stimu- 20:187–208;1947.24. Stephens, G.C. Induction of molting in the crayfish Cambaruslated postexercise and hypoxic conditions. Physiol. Zool. 65:

712–723;1992. by modification of daily photoperiod. Biol. Bull. 108:235–241;1955.14. McDonald, D.G.; McMahon, B.R.; Wood C.M. Patterns of

heart and scaphognathite activity in the crab Cancer magister. 25. Taylor, A.C.; Spicer, J.I. Acid-base disturbances in thehaemolymph of the prawns, Palaemon elegans and PalaemonJ. Exp. Zool. 202:33–44;1977.

15. Mezykowski, T. Diurnal rhythms in metabolism of carbohy- serratus (Crustacea: Decapoda) during exposure to hypoxia.Comp. Biochem. Physiol. 98A:445–452;1991.drate substrates in the antartic krill Euphasia superba. Ekol.

Pol. 27,497–519;1979. 26. Vernberg, F.J. Respiratory adaptations. In: Bliss, D.E. (ed).The Biology of Crustacea, Vol. 8. New York: Academic Press;16. Page, T.L.; Larimer, J.L. Entrainment of the circadian locomo-

tor activity rhythm in crayfish. The role of the eyes and caudal 1983:1–42.27. Wiens, A.W.; Armitage, K.B. The oxygen consumption of thephotoreceptor. J. Comp. Physiol. 78:107–120;1972.

17. Penn, G.H. A study of the life history of the Louisiana red- crayfish Orconectes immunis and Orconectes nais in response totemperature and oxygen saturation. Physiol. Zool. 34:39–54;crawfish, Cambarus clarkii Girard. Ecology 24:1–18;1943.

18. Phillips, J.W.; McKinney, R.J.W.; Hird, F.J.R.; Macmillan, 1961.28. Wilkens, J.L.; Wilkens, L.; McMahon, B.R. Central controlD.L. Lactic acid in crustaceans and the liver function of the

midgut gland questioned. Comp. Biochem. Physiol. 56B:427– of cardiac and scaphognatite pacemakers in the crab Cancermagister. J. Comp. Physiol. 90:89–104;1974.433;1977.

19. Prosser, C.L. Physiological variation in animals. Biol. Rev. 30: 29. Wood, C.; Randall, D.J. Haemolymph gas transport, acid-baseregulation and anaerobic metabolism during exercise in the229–262;1957.

20. Rice, P.R.; Armitage, K.B. The effect of photoperiod on O2 land crab (Cardisoma carnifex). J. Exp. Zool. 218:23–35;1981.