Crayfish Orconectes Virilis Research Articles

Toxicity and accumulation of cadmium in the crayfish,Orconectes virilis (Hagen)

The acute toxicity of cadmium to the crayfishOrconectes virilis was determined over a two week exposure period. Crayfish exhibited an increased sensitivity to cadmium over time; LC50 values decreased from 6.1 mg Cd/L for 96 hr to 0.70 mg Cd/L for 14 days. An incipient LC50 value of 0.06 mg Cd/L was also calculated forO. virilis. Whole animal and tissue analyses for cadmium were performed on the crayfish used in the acute toxicity experiments. Whole animal cadmium concentrations exhibited a linear relationship to exposure concentrations as did the gill and antennal glands. Cadmium tissue concentrations were from highest to lowest in the following tissues: gill > hepatopancreas > antennal gland > carapace and abdominal muscle.

Effects of aluminum and acid on calcium uptake by the crayfishOrconectes virilis

Aluminum increases in concentration in acidified waters and is sometimes more toxic to aquatic organisms at acidic than at neutral pH. This paper examined the interaction of pH and Al in inhibiting uptake of Ca++ from lake water by postmolt crayfish,Orconectes virilis (Hagen). Aluminum at 200 μg/L in non-acidified media had no effect on45Ca uptake. Media at pH 5.5 without Al reduced45Ca uptake to 30% of that in non-acidified media. Aluminum at each of the concentrations of 200, 500 or 1,000 μg/L in media at pH 5.5 reduced45Ca uptake slightly more, to about 20% of that in non-acidified media. The degree of inhibition of45Ca uptake by Al in acidified media was not related to its concentration. Lack of dose-response may be explained by the limited solubility of Al salts and the limited concentrations of the toxic monomeric species which are present in spite of increases in total Al concentration. These toxic species are presumably in the dialyzable fraction of Al which represented 6 to 17% of total lumogallion-reactive Al in media at pH 5.5 and 1 to 10% of total reactive Al at pH 7.O. At pH 5.5, concentration of dialyzable Al was only 67% higher in 1,000 μg/L than in 200 μg/L Al media. Lack of Al toxicity at pH 7.0 may be explained by changes in Al species to less toxic species and/or the apparent lower solubility of A1C13 in the Precambrian Shield lake water at pH 7.0 than at 5.5. Aluminum toxicity constitutes a small additional stress to moltingO. virilis in softwater lakes acidified to between pH 6.0 and 5.0 which have elevated Al levels. In this pH range, natural populations ofO. virilis subject to acidification fail, apparently because of difficulties of ionic regulation coupled with other factors.

Increased microsporidian parasitism of the crayfishOrconectes virilis in an experimentally acidified lake

Orconectes virilis has been identified as a host of the microsporidianThelohania contejeani in four lakes in the Experimental Lakes Area (ELA), northwestern Ontario. Prevalence of parasitism increased from 1.7% in autumn 1979, to 6.5% and 7.7% in autumns 1980 and 1981 concomitant with experimental acidification of Lake 223 to pH 5.1. By comparison, mean infection rates observed within three reference lakes were between 0.3 to 0.6%. Enhanced microsporidosis is believed to have contributed to a reduction in annual crayfish survival rates for the Lake 223 population of 8% in 1979 and 18% in 1980 compared to averages calculated for the non-acidified lakes. Hypotheses to explain the ten-fold increase in Thelohania parasitism in Lake 223 over background levels for the ELA region include a) increased probagative ability due to elevated rate of crayfish cannibalism or low pH-favored parasite life cycle, and b) decreased host resistance when under sublethal stress.

Preliminary investigation of effects of sublethal acid exposure on maternal behavior in the crayfish Orconectes virilis.

Preliminary investigation of effects of sublethal acid exposure on maternal behavior in the crayfish Orconectes virilis.

Variation in Rate of Growth in the Crayfish Orconectes Virilis

ABSTRACT Mark-recapture data on individually marked adult Orconectes virilis living in a stream in southeastern Michigan were used to estimate growth rate and survivorship. Growth rates calculated for this population are markedly higher than those published for other populations of this species and are consistent with the exceptional size of these crayfish.

Low pH avoidance by crayfish (Orconectes virilis): evidence for sensory conditioning

Avoidance responses of crayfish (Orconectes virilis) to low pH were tested for individuals from two populations, one inhabiting a reference lake and one from a lake experimentally acidified over a 5-year period to a mean summer epilimnetic pH of 5.3. Adult and yearling crayfish from the reference population displayed a strong avoidance of potentially lethal water of pH 4.5 and below. However, there was no avoidance demonstrated to water above pH 5.0, which is known to seriously impair reproduction of this species. Animals from the acidified lake had noticeably reduced avoidance, significant at only pH 4.0, with no behavioral modification occurring above pH 4.5.

Chemical detection of sex and condition in the crayfishOrconectes virilis

Individual crayfish (Orconectes virilis) were tested for responses to water containing conspecific individuals of several sex-status categories. Isolated males did not react to "self" water but did show aggressive postures while isolated, nonself male water was introduced. Males' responses to female water was different from responses to male water. Water from aggressing males elicited fewer agonistic postures and more "neutral" postures. Females showed little difference in response to waters from different categories of conspecifics.

An Analysis of Scaphognathite Pumping Performance in the Crayfish Orconectes virilis: Compensatory Changes to Acute and Chronic Hypoxic Exposure

Ventilation volume (V̇w), beat frequency of right scaphognathite (fRr), total stroke volume of the scaphognathite pair (Vsw), and the amplitude of the pulse (PP) and mean standing pressure (Pbr) developed within the postbranchial chamber by scapihognathite action have been measured in the crayfish Orconectes virilis. Data were recorded from crayfish acclimated to normoxia (PO₂ = 130 mm Hg), and during acute (< 24 h) and chronic (> 4 days) exposure to hypoxia (PO₂ = 40-60 mm Hg). At values of fRr below 100 beats/min V̇w varied as a function of both Vsw and fRr, both in normoxic and acutely hypoxic animals. Above 100 beats/min, Vsw remained constant in both groups. In acutely hypoxic crayfish, stroke volume was elevated above normoxic values at any given fRr. Long-term acclimation to hypoxia was accompanied by a significant decrease in V̇w through reduction in both fRr and Vsw. In addition, the stroke volume at higher scaphognathite frequencies was significantly lower than in either normoxic or acutely hypoxic crayfish. Calculations of power output for scaphognathite pumping indicate that the power required to produce a given V̇w was unchanged by hypoxic acclimation. Scaphognathite pumping accounted for 1%, 12%, and 4% of total oxygen consumption in chronic normoxia, acute hypoxia, and chronic normoxia, respectively. The scaphognathites of the crayfish thus emerge as variable-stroke, variable-frequency ventilatory pumps. Possible active and passive mechanisms involved in modulating scaphognathite stroke volume are discussed.

Swimming mechanics during acceleration escape responses in crayfish Orconectes virilis

Swimming mechanics during acceleration escape responses in crayfish Orconectes virilis

Intercellular junctions of antennal gland epithelial cells in the crayfish, Orconectes virilis. A freeze-fracture study.

Labyrinth and nephridial canal cells of the crayfish (Orconectes virilis) antennal gland possess two types of intercellular junctions revealed by freeze-fracture studies. Apical margins of the cells are connected by long septate junctions. In replicas, these junctions consist of many parallel rows of 80--140 A intramembrane particles situated on the PF membrane face (EF and PF fracture faces of Branton et al., 1975). Rows of pits are found on the EF fracture face and are deemed complementary to the rows of particles. Moreover, lateral margins of basal regions of the epithelial cells are attached by many intercellular junctions. These contacts are characterized in thin plastic sections by a narrow dense cytoplasmic plaque located subjacent to the plasma membrane at sites of adjoined cells, and 5 to 12 fine strands of dense material that extend across the intercellular gap between adjoined cells. In freeze-fracture replicas, EF intramembrane faces basal to the region of the plasma membrane containing septate junctions exhibit numerous discoid clusters of particles. The particle aggregates, assumed to represent freeze-cleave images of adhering junctions, range from 900 to 3,700 A in diameter, with individual particles about 185 A in diameter. These junctions appear to connect epithelial cell processes formed by basal infoldings of the plasmalemma, and occur between adiacent cells as well as adiacent processes of a single cell. The discrete aggregates of particles resemble replicated desmosomes (Shienvold and Kelly, 1974) and hemi-desmosomes (Shivers, 1976); therefore, they probably do not constitute a basis for electrical coupling between antennal gland epithelial cells.

Starvation, Energy Reserves, and Aggression in the Crayfish Orconectes Virilis (Hagen, 1870) (Decapoda, Cambaridae)

Der Einfluss von Nahrungsentzug auf das aggressive Verhalten des Krebses Orconectes virilis wurde im Labor untersucht. Nach einer Woche Nahrungsentzug kampften die Versuchstiere ofter und langer und gewannen ofter als Kontrolltiere. Nach zwei Wochen Hungern waren diese Unterschiede nicht mehr zu beobachten.

Examination of the Agonistic Behaviour of the Crayfish Orconectes Virilis By Character Analysis

The agonistic behavior of the crayfish Orconectes virilis was observed in the laboratory, with attention to the effects of size, past experience, and displays. Character analysis was utilized to quantify the relative importance of these three factors. I) In short fights, larger animals and animals which had won previous fights had a decided advantage. 2) In long fights, size and past experience seemed to have little influence on who would win. 3) Initiating an interaction gave an animal and advantage in short fights or when both were the same size. 4) Model presentations indicated that postures assumed during fights were effective visual stimuli and that the white areas on appendages are important components of displays. 5) The greatest reduction in uncertainty concerning which behavior pattern would occur at any time in a fight came from knowing the just previous act of the other crayfish. 6) The amount of information transmitted from one crayfish to another by displays increased during fights to a peak of 160 bits (53% uncertainty reduction) in the middle of fights. 7) Partitioning the data into long or short fights and into initiator-won or defender-won fights increased the apparent importance of inter-animal communication.

Mercury in Aquatic Birds at Clay Lake, Western Ontario

Total mercury levels ranging from 2 to 16 ppm in eggs did not appear to affect the hatching and fledging of herring gulls (Larus argentatus). Mercury levels in breast muscles of 5 American widgeons (Mareca americana), 16 mallards (Anas platyrhynchos), 17 blue-winged teals (Anas discors), 21 common goldeneyes (Bucephala clangula), 17 common mergansers (Mergus merganser), and 7 hooded mergansers (Lophodytes cucullatus) averaged 0.5, 6.1, 6.5, 7.8, 6.8, and 12.3 ppm respectively at Clay Lake 4-6 weeks prior to the hunting season in 1971. Methyl mercury in five ducks ranged from 69 to 99 percent of total mercury. Crayfish (Orconectes virilis) muscle contained the highest mercury levels of food items found in esophagi and stomachs of ducks; the high values in breast muscles of hooded mergansers are likely related to their feeding on crayfish.

The Effects of Artificial Aeration on the Depth Distribution of the Crayfish Orconectes virilis (Hagen) in Two Michigan Lakes

Crayfish (Orconectes virilis) usually exhibit seasonal depth distributions in certain northern Michigan lakes based on sex, age and water temperature. After releasing attached young in shallow water, the adult females typically migrate to deeper cold water while the adult males remain in the warm shallow water. This pattern was thought to be related to the sexual maturation cycle. However, when two lakes were artificially aerated and destratified with compressed air, both sexes distributed throughout the lakes. It is, therefore, postulated that under normal conditions of thermal stratification, the social aggression of the larger males forces the females into deeper, colder water and that this aggression is temperature-related. If oxygen or some other factor is not limiting, 10 C seems to be the lowest temperature selected by 0. virilis during the summer. INTRODUCTION Several workers have reported on the movements of crayfish in streams, ditches and ponds (Henry, 1951; Black, 1963; Momot, 1967; Mobberly and Pfrimmer, 1967; Merkle, 1969; Camougis and Hichar, 1959). Others have studied the relationship between movement and density in the laboratory (Bovbjerg, 1956; Mobberly and Owens, 1966). Because of their limited duration and scope, these studies do not reveal the seasonal pattern of movement, and none allude to the movement of crayfish in lakes. Momot (1967) observed a differential seasonal movement of Orconectes virilis from May through August in West Lost Lake, Pigeon River State Forest, Michigan. Momot and Gowing (1972) extended these observations to other lakes in the vicinity of West Lost Lake. Fast (1971) artificially aerated Hemlock and Section Four lakes during the summer of 1970. Section Four was completely mixed, using a diffuse aerator similar to that described by Fast (1968), whereas Hemlock was aerated by a new hypolimnetic aeration system. This system resulted in a greatly increased hypolimnetic oxygen concentration, and the persistence of strong thermal stratification during most of the summer. We studied the effects of both artificial aeration systems on the depth distributions of the crayfish (0. virilis). This afforded an unusual opportunity to observe differences in sea1 Present address: Union Carbide Corporation, Environmental Sciences Program, Corporate Research Department, Tarrytown, New York 10591.

Sarcoplasmic resistivity of crayfish muscle fibers.

The sarcoplasmic resistivity of long- and short-sarcomere muscle fibers in the walking leg extensor muscle of a crayfish (Orconectes virilis) was measured using a single intracellular microelectrode (the method of Dr. O. Schanne). For long-sarcomere fibers, the mean value was 143 ? cm; for short-sarcomere fibers, the mean value was 150 ? cm. There was no significant difference between the two values, but they differed from some given previously in the literature.

The nematocyst toxin of Metridium.

1. Material discharged by isolated nematocysts of Metridium senile senile Linnaeus (1767) has been found to be toxic to crayfish Orconectes virilis Hagen (1870), O. propinquus Girard (1852), and Procambarus econfinae Hobbs (1942).2. The toxin appears to be composed of a proteinaceous, undialyzable fraction, and a dialyzable fraction containing two aromatic amines.3. The amines are probably fused or polysubstituted ring compounds, one of which is carboxylated.4. The crude toxin has varying potency, depending upon the species of assay animal used.5. With the possible exception of histamine, none of the compounds previously suggested as possible components of the nematocyst toxin were found.

Specificity and digestive function of alkaline proteinase from the gastric juice of the crayfish orconectes virilis

1. 1. The oxidized B-chain of insulin was incubated in the presence of an alkaline proteinase isolated from the gastric juice of the crayfish. 2. 2. Peptide maps of insulin digests indicate that the enzyme demonstrates broad proteolytic specificity. 3. 3. Amino-acid analyses of peptide fragments obtained from insulin digests and incubations of the enzyme with some dipeptides of the same sequences as found in the B-chain suggest a preference for leucyl, tyrosyl, and phenylalanyl residues. 4. 4. On die basis of its broad specificity, the alkaline proteinase is proposed as acting in a compensatory manner in that pepsin is not found in the gastric juice.

Physiological properties of cold resistance adaptation in the fresh-water crayfish Orconectes virilis

1. 1. The pattern of O 2 uptake with temperature of measurement in 1, 11 and 21°C acclimated Orconectus virilis was identical in 1°C vs. 11°C crayfish (translation only), but significantly different in 21°C vs. 1°C or 11°C crayfish (translation and rotation). Q 10 determinations confirm these observations. 2. 2. Crayfish acclimated at higher temperatures had higher levels of O 2 consumption between 2 and 26°C (21°C>11°C>1°C), increased blood volumes and decreased intracellular water. 3. 3. The significance of the above observations was discussed with respect to cold resistance adaptation and selective advantages in the external environment.

Unmasking of a photoinhibitory response in the crayfish caudal ganglion following partial anesthesia

1. 1. Local anesthetics in concentrations insufficient for complete block of spontaneous electrical activity will unmask a photoinhibitory response from the caudal ganglion of the crayfish Orconectes virilis (Hagen). 2. 2. The inhibition appears specific to mechanisms associated with photoreception, since d.c. and nicotine will excite the cord under comparable levels of anesthesia. 3. 3. Both the excitatory and inhibitory responses appear to derive from the same primary photochemical events. The primary photoreceptors and the responding interneurons may be separate morphological units.

Isolation of the proteolytic digestive enzymes from the gastric juice of the crayfish orconectes virilis (hagen)

1. 1. Gastric juice extracts of Orconectes virilis demonstrate two pH optima for caseinase activity, one in the acid range at pH 6·0 and the other a broad peak in the alkaline range between pH 7·5 and pH 8·5. 2. 2. Maximum casein hydrolysis is observed at 49°C when gastric juice is incubated for 20 min at pH 6·0 or pH 8·0 indicating that the 35°C assay temperature is in the ascending phase of the activity curve. 3. 3. Gastric juice extracts hydrolyze CGP, Bz-GA and TAME at an optimal pH of 6·0, 7·0 and 8·0 respectively but BTEE and L-leucinamide are not hydrolyzed after incubations at pH 4·0–pH 9·0. 4. 4. Three proteolytic components can be isolated from the gastric juice by vertical acrylamide gel electrophoresis and subsequent assay of eluted components for caseinase activity at pH 6·0 whereas only two components can be detected at pH 8·0. 5. 5. The hydrolysis of TAME is confined to be fastest moving anodal component whereas CGP and Bz-GA activities are attributed to a component of slightly lower mobility. The proteinase of lowest electrophoretic mobility does not hydrolyze any of the synthetic substrates tested. 6. 6. The TAME-specific proteinase is stable only in an alkaline medium and is anionic in gels as low as pH 3·7 indicating that the overall structure of the enzyme differs from the vertebrate trypsins; DFP inhibits esterolytic and proteolytic activities suggesting that the enzyme is a “serine” proteinase. 7. 7. The isolation of a proteinase that attacks CGP and Bz-GA suggests the presence of a carboxypeptidase of less specificity than the vertebrate carboxypeptidases A and B, but the possibility that the component might be an endopeptidase has not been entirely excluded.