Crayfish Orconectes Rusticus Research Articles

Increased salinity affects survival and osmotic response of rusty crayfish Orconectes rusticus Girard, 1852 and northern clearwater crayfish O. propinquus Girard, 1852 (Decapoda: Astacoidea: Cambaridae) as salinity increases: the potential for estuarine invasions

The potential colonization of the rusty crayfish, Orconectes rusticus (Girard, 1852), has previously focused on lakes and streams of northeastern United States and southeastern Canada, but estuaries have not been considered. Rusty crayfish have recently been reported in tributaries of the Chesapeake Bay and the potential exists for crayfishes to invade and spread into the estuary. We determined survival, hemolymph osmotic pressure, and identified possible mechanisms of osmoregulation of the invasive O. rusticus and northern clearwater crayfish, Orconectes propinquus (Girard, 1852), in salinities of 0.5, 5, 15, and 30 ppt. Survival of both crayfishes (>83%) was unaffected at salinities of up to 15 ppt but declined significantly at 30 ppt to 17% for O. rusticus ( P O. propinquus ( P > 0 . 05 ). Hemolymph osmotic pressure in both species was higher than the external medium up to 15 ppt, and then became nearly isosmotic with salinities at 30 ppt with a significant species by treatment interaction ( F 3 , 55 = 4 . 4627 , P = 0 . 0071 ). The primary osmoregulatory mechanisms in crayfishes involve ions (Na + and Cl − ) and free amino acids (FAAs) in muscle tissues. Concentrations of Na + and Cl − increased with increasing salinity in both species and accounted for 74-91% of the total hemolymph osmotic pressure with a significant species (Pillai’s Trace = 0.9565, P 0 . 05 ). FAA in tail muscle tissue increased significantly with increasing salinity with a significant species by treatment interaction ( F 3 , 20 = 5 . 1911 , P = 0 . 0082 ). Both O. rusticus and O. propinquus were active in salinities of up to 15 ppt and were able to osmoregulate. Based on these laboratory experiments, the potential exists for both of these species to spread through large areas of estuaries into new rivers potentially threatening previously isolated watersheds.

Range expansion of the invasive rusty crayfish Orconectes rusticus (Girard, 1852) (Decapoda: Astacoidea) in northeastern Iowa (USA) rivers

The rusty crayfish Orconectes rusticus (Girard, 1852) is an invasive species that has been introduced to the Upper Midwest, USA from the Ohio River Valley, and is associated with ecological damage to aquatic systems. We examined the distributions of rusty and native crayfishes in two Iowa river systems. One hundred sites were surveyed in the upper Cedar and middle Wapsipinicon river drainages from 2013 to 2014. Four native crayfish species were collected, and contrary to a study conducted in 2002, the rusty crayfish was documented in the mainstream of both systems. Analysis of sampling methods indicates that crayfish capture rates were significantly higher in cylindrical minnow traps than in flat crayfish traps. Genetic analyses confirmed field identifications and support a single introduction of the rusty crayfish in northeastern Iowa. The pervasive distribution and life history characteristics of the rusty crayfish suggest that eradication is currently not feasible. Further monitoring is warranted in order to determine its distribution throughout Iowa’s river systems.

Comparison of 13C and 15N discrimination factors and turnover rates between congeneric crayfish Orconectes rusticus and O. virilis (Decapoda, Cambaridae)

Ecological applications of stable isotope analysis are dependent on knowing consumer-diet discrimination factors (Δ) and consumer metabolic turnover rates (m). We used an 80-day laboratory experiment to test for differences in the δ13C, δ15N and m of two species of crayfish (Orconectes rusticus and O. virilis) fed one of two diets (algae wafers and bloodworms). Over the course of the experiment, the δ13C and δ15N signatures of the crayfish approached equilibrium with those of their diets. We fit our data to a growth-based model and found δ13C, δ15N, and m to be largely indistinguishable between species, except in the case of δ15N and m of crayfish on the algae diet. We thus pooled parameters to calculate Δ13C (algae diet: 1.57‰ [95% confidence interval: 0.86–2.35]; bloodworm diet: 0.8‰ [0.14–1.55]) and Δ15N (bloodworm diet: 1.2‰ [0.32–2.11]), and used species-specific data to calculate Δ15N for the algae diet (O. rusticus: 2.54‰ [2.06–3.08]; O. virilis: 3.35‰ [2.53–4.51]). Our results provide values of stable isotope Δ and m for applications to crayfish, and offer a rare comparison of these values between two closely related species and to commonly used literature values.

Optimizing sampling effort to detect rusty crayfish (Orconectes rusticus) in southern Ontario rivers

The distribution and status of native and non-native crayfish are monitored across hundreds of lakes in Ontario (Canada). However, a corresponding effort has not been undertaken in flowing waters. Reliable and efficient sampling methods are essential for the detection of new aquatic invaders and tracking the spread of existing invasive species. In this study, a recent dataset for the invasive rusty crayfish (Orconectes rusticus) was used to determine whether the detection probability associated with intensive sampling by hand-capture (20 minutes) of 10 transects could be achieved with fewer transects. Results indicate that sampling more than three transects does not improve rusty crayfish detection. Monitoring designs based on three transects would reduce search effort by 140 minutes at each site; permitting greater spatial coverage or more frequent sampling.

Evaluating the Need for Supplemental Shallow Water Access for Amphibians Reared in Mesocosms

Mesocosms are an important tool in experimental aquatic ecology, but have been criticized for failing to effectively mimic natural habitats. Identifying contrived features of mesocosms that affect endpoints of interest is a prudent step in ensuring the reliability of mesocosm data. Because anuran larvae actively regulate their exposure to a suite of biotic and abiotic conditions by positioning themselves at various depths in natural ponds, the steep walls and minimal access to shallow regions in common cattle tank mesocosms may force tadpoles into sub-optimal patterns of habitat use. We tested whether adding angled ramps or horizontal platforms to increase access to shallow regions affected survival, time, or mass at metamorphosis of American Toads (Anaxyrus americanus) or Northern Leopard Frogs (Lithobates pipiens) in the presence or absence of Rusty Crayfish (Orconectes rusticus), a common predator that may influence habitat use. Addition of structure had no effect on American Toad survival or metamorph...

Prey responses to fine-scale variation in predation risk from combined predators

While it is well documented that organisms can express phenotypic plasticity in response to single gradients of environmental variation, our understanding of how organisms integrate information along multiple environmental gradients is limited in many systems. Using the freshwater snail Helisoma trivolvis and two common predators (water bugs Belostoma flumineum and crayfish Orconectes rusticus), we explored how prey integrate information along multiple predation risk gradients (i.e. caged predators fed increasing amounts of prey biomass) that induce opposing phenotypes. When exposed to single predators fed increasing amounts of prey biomass, we detected threshold responses; intermediate amounts of consumed biomass induced phenotypic responses, but higher amounts induced little additional induction. This suggests that additional increases in predator-induced traits with greater predator risk offer minimal increases in fitness or that a limit in the response magnitude was reached. Additionally, the response thresholds were contingent on the predator and focal trait. For shell width, responses were generally detected at a lower amount of consumed biomass by water bugs compared to crayfish. Within the crayfish treatments, we found that the shell thickness response threshold was lower than the shell width response threshold. When we combined gradients of consumed biomass from both predators, we found that the magnitude of response to one predator was often reduced when the other predator was present. Interestingly, these effects were often detected at consumed biomass levels that were lower than the threshold concentration necessary to elicit a response in the single-predator treatments. Moreover, our combined predator treatments revealed that snails shifted from discrete responses to more continuous (i.e. graded) responses. Together, our results reveal that organisms experiencing multiple environmental gradients can integrate this information to make phenotypic decisions and demonstrate the novel result that an exposure to multiple species of predators can lower the response threshold of prey.

The effects of sublethal levels of 2,4-dichlorophenoxyacetic acid herbicide (2,4-D) on feeding behaviors of the crayfish O. rusticus.

The widespread use of herbicides across the globe has increased the probability of synthetic chemicals entering freshwater habitats. On entering aquatic habitats, these chemicals target and disrupt both physiological and behavioral functioning in various aquatic organisms. Herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-D), can have negative impacts on chemoreception because these receptor cells are in direct contact with water-soluble chemicals in the environment. Studies focusing on lethal concentration (LC50) levels may understate the impact of herbicides within aquatic habitats because damage to the chemoreceptors can result in modified behaviors or lack of appropriate responses to environmental or social cues. The purpose of this experiment was to determine whether exposure to sublethal levels of 2,4-D alters the foraging behaviors of crayfish Orconectes rusticus. We hypothesized that crayfish exposed to greater concentrations of 2,4-D would be less successful in locating food or on locating food would consume smaller amounts possibly due to an inability to recognize the food odors in the contaminated waters. Crayfish were exposed to three sublethal levels of 2,4-D for 96 h and placed into a Y-maze system with a fish gelatin food source placed randomly in the right or left arm. Average walking speed, average time spent in the correct arm, and percent consumption were analyzed. Our data show that crayfish were impaired in their ability to forage effectively. These inabilities to locate and consume adequate amounts of food could result in lower body weights and decreased fitness in populations of crayfish exposed to 2,4-D in natural habitats.

Complex predator–prey interactions between the rusty crayfish (Orconectes rusticus) and invertebrate and vertebrate prey within their native range

Crayfish can have profound effects on native species where they are introduced, yet few studies have examined the role of crayfish predation on species within their native ranges. We examined interactions between predatory rusty crayfish (Orconectes rusticus) and invertebrate and vertebrate prey in Southeast Indiana, where the crayfish are a native species. We conducted multiple experiments, which included assessing the predation efficiency of rusty crayfish on salamander larvae (Eurycea cirrigea) and aquatic isopods (Lirceus fontinalis), the role of substrate in prey survival, prey responses to chemical stimuli from crayfish, and the distribution of each species in a natural stream setting. We found that crayfish almost completely eliminated isopods, but the addition of even a simple gravel substrate dramatically increased survival. Although the size of the crayfish had no effect on isopod survival, salamander larvae were more likely to survive in the presence of smaller crayfish. Neither prey species responded to chemical stimuli from crayfish, yet field observations indicated that crayfish and isopods inhabit different microhabitats within the stream. Finally, the interaction between crayfish and salamander larvae is complex with the crayfish size and the natural distribution of size classes in streams likely reducing the larval predation risk and permitting coexistence. These results indicate that although crayfish are major predators on both invertebrates and vertebrates, coexistence over evolutionary time has likely led to multiple behavioral adaptations to avoid these predators.

Interactive effects of calcium decline and predation risk on the potential for a continuing northward range expansion of the rusty crayfish (Orconectes rusticus)

Over the last three decades, the rusty crayfish (Orconectes rusticus (Girard, 1852)) has been expanding its range northward via human-mediated dispersal. If this species is to continue expanding its range northward, it will move onto the Canadian Shield, where calcium (Ca) availability is low and is predicted to decline further in the future. Dissolved Ca is a vital functional component of mollusc and crustacean physiology, important for exoskeletal condition and strength, as well as metabolic activity. However, some organisms are able to compensate for reduced structural integrity by modifying their behaviour. In this study, we asked if the invasive O. rusticus can survive low levels of ambient Ca and, if it can, whether it exhibits modified antipredator behavior in response to the physiological limitations imposed by low [Ca]. We found that, under reduced Ca levels, O. rusticus reduced the frequency of standard activities (such as grooming and foraging) and was more likely to engage in vigilance and (or) escape behavior. We also found that some individuals, in extremely low [Ca], died while molting. This study suggests that Ca limitation on the Shield, especially where predators are present, may limit the northward expansion of O. rusticus beyond their current range limit.

Invasive crayfish Orconectes rusticus (Decapoda, Cambaridae) is a more effective predator of substrate nesting fish eggs than native crayfish (O. virilis)

Non-indigenous crayfish pose substantial threats to native species, community structure, and ecosystem function in invaded lakes across the globe. The well-documented range expansion of the rusty crayfish Orconectes rusticus is an ideal system to study potential relationships between the attributes that contribute to invasive success, and the ways in which non-indigenous species alter invaded systems. In Michigan and northern Wisconsin (U.S.A.) lakes where O. rusticus is replacing its native congener O. virilis, it is thought that O. rusticus invasion may account for decreased fish abundance. However, not all of the potential mechanisms that could drive this process have been explored. We examined the hypothesis that O. rusticus are better benthic egg predators than O. virilis, and tested the prediction that O. rusticus would consume substrate bound fish eggs at a higher rate than its native congener. Support for this hypothesis would suggest that O. rusticus may be able to access a high-energy food source better than O. virilis, and exert predation pressures that could limit the abundance of fish species which might otherwise limit crayfish populations through top-down control. In laboratory experiments, we determined that O. rusticus exhibit a positive correlation between feeding rate and carapace length not displayed by O. virilis, and that larger O. rusticus feed at a higher rate than their native congener. We also found that O. rusticus in laboratory feeding trials engaged in longer feeding events than crayfish foraging in situ in a substrate-spawning fish nest, a factor which could give O. rusticus an advantage in resource competition with its native congener O. virilis. Collectively, these findings support the hypothesis that O. rusticus is a better predator of substrate bound fish eggs than O. virilis, and suggest that direct predation by crayfish may influence fish reproduction in lakes where O. rusticus replaces O. virilis.

A comparative analysis of setae on the pereiopods of reproductive male and female Orconectes rusticus (Decapoda: Astacidae)

The pereiopods (walking legs) of crustaceans have been shown to have both mechano- and chemosensory functions including: detecting various odors, mechanical stimuli, as well as being used for grooming of gills and brood care. Using scanning electron microscopy, we examined the pereiopods of reproductive male (form I) and reproductive female (glair) crayfish Orconectes rusticus Girard, 1852 and found that the distal portion (dorsal surface) of the propodus of pereiopods 2 through 5 contain smooth, plumose, serrate and cuspidate setae. Various studies have implicated both smooth and serrate setae as being important for grooming; therefore, we used scanning electron microscopy to examine and compare the distribution of smooth and serrate setae on the pereiopods of reproductive male and female crayfish in order to determine if there were differences between sexes. We found that there were no differences in the number of tufts (pockets) or number of smooth setae on the second and third pereiopods (chelipeds) between male and female crayfish. Further, the second and third pereiopods of both male and female crayfish had significantly more smooth setae than the fourth and fifth pereiopods. When the distribution of serrate setae was compared, we found that reproductive female crayfish possess significantly more serrate setae on their fifth pereiopods than their fourth pereiopods and both pereiopods 4 and 5 of form I male crayfish. Overall, increases in serrate setae on the fifth pereiopods of reproductive female crayfish are significant. We suggest that female crayfish may use serrate setae of the fifth pereiopods extensively for grooming eggs and brood care during reproduction.

Associative learning in male rusty crayfish (Orconectes rusticus): conditioned behavioural response to an egg cue from walleye (Sander vitreus)

Chemical communication governs a diversity of life processes in aquatic organisms. Crayfish use chemoreception during reproduction, social hierarchy formation, predation avoidance, and resource localization. Fish eggs release recognizable chemoattractants for vertebrate predators of eggs that can motivate crayfish to engage in egg predation as well. We hypothesized that male rusty crayfish ( Orconectes rusticus (Girard, 1852)) from a lake free of walleye ( Sander vitreus (Mitchill, 1818)) would not possess an innate recognition of a walleye egg cue. However, if conditioned by employing a single 2 h paired stimulus exposure (known food cue + egg cue), then male rusty crayfish would be attracted to the same egg cue upon subsequent exposure. Using a Y-maze behavioural arena we discovered that once conditioned, crayfish took significantly less time to choose the arm containing the egg cue alone relative to a control. Our study suggests that male rusty crayfish exhibit second-order conditioning through associative learning, allowing them to quickly and easily learn to identify novel odour stimuli from fish eggs under laboratory conditions.

Morphological Variation of Rusty Crayfish Orconectes rusticus (Cambaridae) with Gender and Local Scale Spatial Gradients

We tested for the influence of gender, stream, and urbanization on morphological variation in rusty crayfish (Orconectes rusticus) in an east-central Indiana, US watershed. We used geometric morphometrics to characterize shape and tested for differences among and within sites. Males had shallower rostrum, increased head width and length, decreased abdomen and cephalothorax width and length, and increased telson length compared to females. Morphology of males did not vary with stream or along an urban gradient. The morphology of females varied with stream and along an urban gradient. Female shapes from small creek sites were stouter and less fusiform than larger river specimens. Following an urban gradient, females exhibited an increasingly reduced abdominal and telson area and a more fusiform rostrum. Morphological variation is linked with adaptation and subsequent success of aquatic taxa. Disentangling the potential influences on crayfish morphology has implications for improved understanding of ecosystem structure and conservation.

Predation by native sunfishes (Centrarchidae) on the invasive crayfish Orconectes rusticus in four northern Wisconsin lakes

Tetzlaff JC, Roth BM, Weidel BC, Kitchell JF. Predation by native sunfishes (Centrarchidae) on the invasive crayfish Orconectes rusticus in four northern Wisconsin lakes. Ecology of Freshwater Fish 2011: 20: 133–143. © 2010 John Wiley & Sons A/SAbstract – Introduced rusty crayfish (Orconectes rusticus) often establish abundant populations in lakes where they negatively impact native food webs. However, rusty crayfish do not become abundant in all lakes. Fish predation has been posed as one potential mechanism limiting rusty crayfish density, but there is limited empirical evidence to support this hypothesis. Using a case study approach, we quantified the extent and timing of predation on nonnative rusty crayfish by three native centrarchids in four northern Wisconsin lakes with contrasting crayfish densities. We estimated population‐level predation effects on rusty crayfish using bioenergetics models in combination with fish and crayfish abundance estimates. Bluegill (Lepomis machrochirus) and pumpkinseed (Lepomis gibbosus) consumed young‐of‐year crayfish exclusively whereas rock bass (Ambloplites ruspestris) consumed a wide size range of crayfish. Rusty crayfish were found in Lepomis diets primarily in late June and early July while rock bass consumed crayfish throughout the summer. Per individual, rock bass consumed more crayfish biomass than Lepomis, but at the population‐level, higher Lepomis densities resulted in greater numbers of crayfish and more crayfish biomass consumed by Lepomis than rock bass. Lepomis populations consumed 8 × , 14 × , 22 × and 120 × more individual crayfish than rock bass populations in the four study lakes. Bioenergetics simulations revealed that dense populations of Lepomis were capable of consuming a large percentage of the juvenile crayfish population in two of our study lakes. In systems with high Lepomis densities, Lepomis consumption of juvenile rusty crayfish may play a significant role in the invasion and establishment dynamics of rusty crayfish.

Potential and realized interactions between two aquatic invasive species: Eurasian watermilfoil (Myriophyllum spicatum) and rusty crayfish (Orconectes rusticus)

With multiple invasions, the potential arises for interactions between invasives inhibiting or promoting spread. Our goal was to investigate the interaction between two invasives, Eurasian watermilfoil ( Myriophyllum spicatum ) and rusty crayfish ( Orconectes rusticus ), which co-occur in several lakes in western Quebec, Canada, and to determine their overlap with littoral fish communities. Crayfish potentially aid milfoil dispersal by fragmentation or, alternatively, inhibit its proliferation through destruction and direct consumption. With a mesocosm experiment, we quantified milfoil fragment production versus biomass reduction by crayfish. More fragments were produced at medium to high crayfish densities, with a significant reduction of milfoil only at the highest densities, demonstrating the potential for both positive and negative interactions. Second, we determined the habitat preferences of each species by conducting a survey in the same lake. There was little overlap in the species’ distributions, with each preferring different habitat features, indicating either a low probability of interaction or that interaction occurred historically, resulting in a contemporary exclusion pattern. While our experiment showed a potential for significant interaction, the low natural co-occurrence of these species suggests that they do not currently influence each other or that they previously excluded each other.

Ontogenetic Variation in Food Consumption of Rusty Crayfish (Orconectes rusticus) in a Central New York Stream

ABSTRACT We examined feeding periodicity of three size groups of the rusty crayfish (Orconectes rusticus) at four-hour intervals over a 28-hour period during July in a headwater stream of the Susquehanna River drainage in central New York. Feeding activity was expressed as the ratio of stomach weight divided by the crayfish wet weight. The diel food consumption patterns of all three size groups of rusty crayfish (i.e., ≤ 10 mm, 11–20 mm, and > 20 mm carapace length) were significantly different. Peak feeding of the smallest crayfish occurred during crepuscular periods. Food consumption of the intermediate size crayfish was highest at 2000 h, and feeding of large crayfish was consistently high from 1200 h to 0400 h. Feeding intensity of both small and intermediate size crayfish was highest when feeding intensity of large crayfsh was lowest. Ontogenetic differences in feeding periodicity may be associated with predation pressure from large rusty crayfish on smaller individuals.

Distribution and community-level effects of the Chinese mystery snail (Bellamya chinensis) in northern Wisconsin lakes

Managing invasive species requires information about their distributions and potential effects, but community-level impacts of invasive animals remain poorly understood. The Chinese mystery snail (Bellamya chinensis) is a large invasive gastropod that achieves high densities in waters across North America, yet little is known about its ecological significance in invaded systems. We surveyed 44 lakes to describe the patterns and determinants of B. chinensis distributions in northern Wisconsin, USA, and to assess the likelihood of effects on native snail communities in the invaded systems. B. chinensis was widespread among surveyed lakes (21 of 42 lakes with snails) and its occurrence was correlated with indicators of lake productivity and anthropogenic dispersal vectors (boat landings, distance to population centers, shoreline housing density). Some native snail species tended not to occur at sites where B. chinensis was abundant; among these was Lymnaea stagnalis, which suffered reduced survival in the presence of B. chinensis in a recently published mesocosm study. However, there was no difference in overall snail assemblage structure at either the site or lake level as a function of B. chinensis presence or abundance. Lake occurrences of many snail species have apparently been lost over time, but a comparison to a 1930s survey showed that there was no increased likelihood of species loss in lakes invaded by B. chinensis (or by the invasive crayfish Orconectes rusticus). Although B. chinensis is widespread and sometimes abundant in northern Wisconsin lakes, it does not appear to have strong systematic impacts on native snail assemblages.

Multispecies crayfish declines in lakes: implications for species distributions and richness

Aquatic communities are highly threatened by anthropogenic and climate change. However, despite their importance in these communities, information regarding temporal changes in populations and assemblages of North American crayfish is scarce. Long-term monitoring of crayfish populations in south-central Ontario, Canada, indicates that the populations are in a significant state of decline. We sought to determine whether these population declines are spatially and taxonomically broad, and if so, what factors might be associated with the declines. We sampled crayfish abundance (catch per unit effort) in 100 lakes, and compared current abundances to survey results from the early 1990s. Abundances of all species (natives and nonnatives) declined significantly during this interval. Declines were both severe (63–96% loss of abundance) and geographically widespread for all species. Previous studies have documented native species declines caused by the invasive crayfish Orconectes rusticus, but this species was absent from almost all lakes and was not a factor in the declines. We hypothesize that the introduction of predatory smallmouth bass (Micropterus dolomieui), increases in Al concentrations, and reduced Ca concentrations in these lakes are negatively affecting crayfish populations.

Experimental Evidence That Captured Rusty Crayfish (Orconectes rusticus) Exclude Uncaptured Rusty Crayfish from Entering Traps

ABSTRACT Baited modified minnow traps are often used to collect rusty crayfish (Orconectes rusticus), an invasive species in many areas of North America. However, the use of baited traps as a collection gear for decapods has received considerable scrutiny. We designed a tank-experiment to determine if captured rusty crayfish exclude uncaptured rusty crayfish from baited traps. We found that significantly more crayfish were captured in traps where captured crayfish were immediately removed (experimental tanks) than in traps where crayfish were not immediately removed (control tanks). In addition, more small crayfish were captured in the experimental tanks. These results are consistent with a hypothesis that large and aggressive previously captured rusty crayfish exclude other, generally smaller, rusty crayfish from the trap.

Attachment and Shell Integrity Affects the Vulnerability of Zebra Mussels (Dreissena polymorpha) to Predation

ABSTRACT We investigated the relationship between prey condition and predation vulnerability in the zebra mussel (Dreissena polymorpha). In aquarium experiments with rusty crayfish (Orconectes rusticus), a known predator of the zebra mussel, both removal of the zebra mussels from their substrata and damage to their shells significantly increased their vulnerability to predation. This result was corroborated in open-water trials in Douglas Lake, Michigan, USA. The effect of shell damage on predation of the mussels was less pronounced in the lake than in the laboratory, probably owing to the presence in the lake of alternative prey items for predators. In the lake trials, there was a significant negative correlation between predation and the distance the samples were set from the shoreline. Although zebra mussels can be important food items for molluscivore predators, their vulnerability to predators which use chemical cues such as rusty crayfish appears to be directly related to the integrity of the mussel shell and/or their byssus (attachment) threads.