Behavioral thermoregulation of largemouth bass,Micropterus salmoides,and bluegill,Lepomis macrochirus,in a nuclear reactor cooling reservoir

Synopsis Behavioral responses which allow largemouth bass, Micropterus salmoides, and bluegill, Lepomis macrochirus, to survive under unusually high temperature conditions were examined. Distribution of fish was ascertained by angling. Body temperatures of 4 fish were obtained using radio transmitters. Temperatures of other fish were measured after fish were captured by angling. Both species were restricted in range by lethal water temperatures and therefore inhabited a greater portion of a thermally altered reservoir in winter than in summer. Under unheated conditions (during reactor shutdown), bass occupied shallow areas with an abundance of submerged logs and stumps, a deep area with springs, and a cove where the effluent canal entered the reservoir. Commencement of reactor operation resulted in an increase in water temperature to more than 50°C in summer. Bass and bluegill retreated to three refuges and remained there until the reactor shut down and the reservoir cooled. In the refuges, bass experienced a wide variety of temperatures, but adults generally avoided temperatures above 31°C. Large adult bass (>40 cm) occupied particular positions in a refuge cove, medium size bass (15–40 cm) swam in the open water, and small bass (相似文献   

Utilizing stomach content and faecal DNA analysis techniques to assess the feeding behaviour of largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus

In this study, the feeding behaviour of the non‐native invasive predatory fishes largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus was studied in the Ezura River, a northern tributary of Lake Biwa, Japan. Prey composition was estimated based on visual examination of stomach contents and faecal DNA analysis to determine feeding habits of these predatory fishes. Stomach content analysis showed that native fishes (e.g. ayu Plecoglossus altivelis and gobies Rhinogobius spp.) and shrimps (e.g. Palaemon paucidens) were the major prey items for M. salmoides, while snails, larval Chironomidae and submerged macrophytes were the dominant prey items of L. macrochirus. Micropterus salmoides tended to select larger fish in the case of crucian carp Carassius spp., but smaller fishes in the case of P. altivelis and Rhinogobius spp. Faecal DNA analyses revealed prey compositions similar to those identified in predator stomach contents, and identified additional prey species not detected in stomach content inspection. This study demonstrated that both stomach content inspection and DNA‐based analysis bear several inherent shortcomings and advantages. The former method is straightforward, although identification of species can be inaccurate or impossible, whereas the latter method allows for accurate species identification, but cannot distinguish prey size or stage. Hence, integration of morphology‐based and DNA‐based methods can provide more reliable estimates of foraging habits of predatory fishes.     

The complete mitochondrial genomes of largemouth bass of the northern subspecies (Micropterus salmoides salmoides) and Florida subspecies (Micropterus salmoides floridanus) and their applications in the identification of largemouth bass species

The largemouth bass belongs to the family Centrarchidae, which includes two subspecies: the northern subspecies, Micropterus salmoides salmoides, and the Florida subspecies, Micropterus salmoides floridanus. In this study, the complete mitochondrial genomes of the two subspecies were sequenced, and their genetic differences were identified. The mitogenomes of M. s. salmoides and M. s. floridanus are 16,486 and 16,479?bp in length, respectively. The two subspecies consisted of 37 genes (13 protein-coding genes, 2 ribosomal RNA, and 22 transfer RNA), which are typical for vertebrate mtDNA. Phylogenetic analysis provided statistical support for the monophyly of the family Centrarchidae. Comparison of the two subspecies' mitogenomes revealed a relatively high number (450) of single nucleotide polymorphisms (SNPs) in protein-coding genes. We characterized SNPs in the partial cytochrome c oxidase subunit 1 gene of different individuals from three cultured populations, one wild northern subspecies population, and one wild Florida subspecies population. Twenty-eight SNPs were fixed with alternative nucleotides in the two subspecies, which could be used for differentiating them. Based on this gene, phylogenetic tree and genetic distance analyses supported that cultured largemouth bass in China belongs to the northern subspecies.     

Choice in the bluegill (Lepomis macrochirus)

To study matching in a species distantly related to mammals and birds, seven bluegill were trained to break a photobeam using a nose-poke response for access to pelleted food in their home aquaria during one-h sessions. Reinforcer ratios available from the two response alternatives varied among the following: 16:1, 8:1, 4:1, 1:1, 1:4, 1:8, and 1:16. The overall reinforcement rate was held at 0.8/min. All experiments were conducted in a closed economy, i.e., the fish's daily food ration was available only during experimental sessions. Matching functions are reported for each fish using all combinations of scheduled and obtained reinforcer ratios as the independent variables and response and time ratios as the dependent variables. All matching functions had slopes less than 1.0 and r² values above 0.70. Overall response rates were unrelated to the reinforcer ratios but, as with other species studied, changeover rates were highest for the 1:1 condition and lowest for the 16:1 conditions. These results are consistent with data obtained from more traditionally studied taxa (e.g., birds, mammals, and primates), and similar previous studies with fish, suggesting that matching has been conserved since fish, birds, and mammals evolved from a common ancestor over 400 million years ago.     

Considerations of blood parameters of largemouth bass, Micropterus salmoides

To evaluate physiological stress resulting from environmental influences, a haematological study of a natural population of largemouth bass, Micropterus salmoides , was undertaken to establish a 'normal' blood profile. Several parameters including haemoglobin concentration, haematocrit, erythrocyte count, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, plasma protein concentration and glucose levels were investigated. Haematocrit, haemoglobin, and total plasma protein were positively correlated with fish length. Haemoglobin and haematocrit were positively correlated with fish age while mean corpuscular haemoglobin, concentration was negatively correlated with fish age. Both haemoglobin and haematocrit values were related to erythrocyte counts.     

Observations on the ecology of Clinostomum marginatum in largemouth bass (Micropterus salmoides)

Over a fifteen month period, beginning October, 1974, approximately 13 500 centrarchids were examined for evidence of infection with metacercaria of Clinostomum marginatum. Species checked included Lepomis macrochirus, L. gulosus, L. auritus, Pomoxis nigromaculatus and Micropterus salmoides. The study site was Par Pond (South Carolina, U.S.A.), an 1120 ha reservoir receiving thermal effluent from a nuclear production reactor. Except for the largemouth bass, M. salmoides , infection percentages among the five species were less than 1%. Among bass, infection varied seasonally, being highest from January to June. From the spring highs of approximately 25 %, the percentages dropped to lows of < 10% in July and August; there was a jump in September-October to another peak of 30% and then a steady decline through December when infection percentages were again less than 10%. Neither body condition nor length of the bass were related to infection percentage or metacercaria density. Infection percentage could not be related to the influence of thermal effluent. Infection percentages did vary from location to location within the Par Pond system. A significant rank correlation could be established between infection percentage and the amount of littoral zone present in the locality from which the bass were taken. It is suggested that the local 'bay effects' are the result of limited home and foraging ranges of the bass in relation to the amounts of littoral zone present in various locations of the reservoir.     

Ontogenetic diet shifts and interrupted piscivoryin introduced largemouth bass (Micropterus salmoides)

The ecology of largemouth bass (Micropterus salmoides) is one of the best known for freshwater fish, though largely through studies within its native range (North America). I studied the habitat and diet of a bass population introduced into a Mediterranean lake. The bass displayed strong ontogenetic diet shifts as follows: young‐of‐the‐year <25 mm fed on microcrustaceans; fish 25–75 mm, on amphipods and insects; fish 100–225 mm, on a freshwater shrimp, small fish and insects; fish 250–300 mm, on shrimp or crayfish; and fish >300 mm, on crayfish and large fish. The diet showed several differences from most previous studies: importance of freshwater shrimp instead of insects, low piscivory, and a delay in the ontogenetic shift to piscivory. Moreover, the ontogenetic shift to piscivory was interrupted at 250–300 mm, with consumption of shrimp and crayfish. This interruption of piscivory has been largely unreported and seems a consequence of the size‐structure and species composition of the fish assemblage. A review of the literature suggests that piscivory by largemouth bass might be generally lower in populations introduced outside North America.     

A successful population of largemouth bass, Micropterus salmoides, in a subtropical lake in Mozambique

Sectioned otoliths were used for age and growth determination of the alien Micropterus salmoides from Lake Chicamba, a hydroelectric dam in central Mozambique. Marginal zone analysis showed that annulus formation occurred during winter in August and September. The maximum estimated age was 5 years. Growth was described by the 3 parameter von Bertalanffy model as L_t=465.51 (1 – e^{-1.175(t+0.009)}) mm FL. Juvenile growth rate was 23.1 mm per month during their first 7 months of life. The age at 100% maturity was 0.9 years, and spawning occurred during August and September. The juvenile fish fed sequentially on the most abundant prey items. Spawning occured before any of the indigenous fish species and so, there is little inter-specific competition. Conspecific juveniles formed the most important constituent in the adult M. salmoides diet from October to December when alternative prey was limited. The total annual mortality rate (Z) for the species in Lake Chicamba was 1.27 yr^-1, the mean empirical estimate of natural mortality (M) was 0.73 yr^-1, and fishing mortality (F) was calculated at 0.54 yr^-1. The success of M. salmoides in Lake Chicamba was attributed to limited inter-specific and intra-specific competition for prey as a consequence of the timing of the spawning, cannibalism and high mortality rates.     

Description of two new gill myxozoans from smallmouth (Micropterus dolomieu) and largemouth (Micropterus salmoides) bass

Two previously undescribed species of myxozoan parasites were observed in the gills of bass inhabiting the Potomac and James River basins. They are described using morphological characteristics and small-subunit (SSU) rDNA gene sequences. Both were taxonomically identified as new species of Myxobolus; Myxobolus branchiarum n. sp. was found exclusively in smallmouth bass, and Myxobolus micropterii n. sp. was found in largemouth and smallmouth bass. Small, spherical, white plasmodia of M. branchiarum from smallmouth bass were observed grossly in the gills; these plasmodia had an average length of 320.3 μm and width of 246.1 μm. The development of the plasmodia is intralamellar in the secondary lamellae of the gills. Mature spores were pyriform in shape with a length of 12.8 ± 1.4 (8.1-15.1) μm and width of 6.9 ± 1.1 (4.0-9.0) μm. Analysis of SSU rDNA identified M. branchiarum in a sister-group to 3 species of Henneguya , although morphologically caudal appendages were absent. Myxobolus micropterii observed in the gills of largemouth and smallmouth bass had larger, ovoid, cream-colored plasmodia with an average length of 568.1 μm and width of 148.1 μm. The cysts developed at the distal end of the gill filament within the primary lamellae. The mature spores were ovoid in shape with a length of 10.8 ± 0.7 (9.2-12.2) μm and width of 10.6 ± 0.6 (9.0-11.8) μm. SSU rDNA analysis placed M. micropterii in a sister group with Henneguya lobosa and Myxobolus oliveirai . The highest prevalence of M. branchiarum was observed in the gills of bass collected from the Cowpasture River (50.9%). Prevalence was 44.6% in bass from the Potomac River and only 4.3% in bass collected from the Shenandoah River. A seasonal study of M. branchiarum , which included both infected and uninfected smallmouth bass, determined that a significantly higher intensity was observed in the spring than in the summer (P < 0.001) or fall (P = 0.004). In an analysis excluding uninfected bass, a higher intensity was observed in the spring than in the summer (P = 0.001) or fall (P = 0.008). Prevalence and seasonal differences were not determined for M. micropterii .     

Laboratory measurement of preferred body temperature of adult largemouth bass (Micropterus salmoides)

Preferred deep body temperatures of adult bass were determined in the laboratory using a horizontal temperature gradient and telemetry. The method used allowed continuous monitoring of body temperatures of adult bass in the gradient. The preferred temperature of adults (range = 27–32°C) was similar to preferenda reported earlier for sub-adults.     

The effects of temperature change on the hatching success and larval survival of largemouth bass Micropterus salmoides and smallmouth bass Micropterus dolomieu

In this study, the effects of abrupt temperature change on the hatching success and larval survival of eggs, yolk-sac larvae (YSL) and larvae above nest (LAN), for both largemouth bass Micropterus salmoides and smallmouth bass Micropterus dolomieu were quantified. Temperature had a significant effect on hatching success and time to 50% mortality, with large heat shocks causing accelerated mortality. The temperature changes shown to influence survival of all life stages, however, were beyond what is typically experienced in the wild. Micropterus salmoides had greater egg hatching success rates and increased survival rates at YSL and LAN stages, relative to M. dolomieu. Additionally, egg hatching success and survival of LAN varied across nests within the study. These findings suggest that temperature alone may not account for variations in year-class strength and may emphasize the need for protection of the nest-guarding male Micropterus spp. to ensure recruitment.     

Effects of sulphuric acid exposure on the behaviour of largemouth bass,Micropterus salmoides

Synopsis Young-of-the-year largemouth bass,Micropterus salmoides, were exposed to four concentrations of sulphuric acid (pH levels 7.2, 6.1, 4.8, and 3.7) for 30 days, and the frequencies of feeding acts and activity bouts, and time budgets were recorded. Juveniles at pH 6.1 and at pH 4.8 performed the two feeding acts, bites and orientations, more often, and spent more time feeding than bass at pH 7.2. Bass at pH 3.7, however, reduced feeding, and spent a significantly larger portion of their time hovering in the water column. Frequencies of comfort and agonistic acts increased with a decline in pH. Alterations of behavioural repertoires of young-of-the-year largemouth bass were useful indicators of sulphuric acid exposure.     

Predator-prey behaviour of fathead minnows, Pimephales promelas and largemouth bass, Micropterus salmoides in a model ecosystem

The predator-prey behaviours displayed by largemouth bass, Micropterus salmoides and fathead minnows, Pimephales promelas , were investigated. Fathead PRMOWS were subjected to predation by largemouth bass and observed in a model system that was designed to mimic a natural ecosystem. Anti-predator devices utilized by fathead minnows include schooling, surface swimming, formation of a circular aggregation, and seeking refuge under vegetation.     

Examining the effects of chronic,lake-wide elevated temperatures on behavioural expression in largemouth bass,Micropterus salmoides

Many behaviours have differential fitness consequences across thermal and ecological contexts, indicating that both ecological shifts and warming temperatures induced by climatic change may alter how organisms behave. However, empirical evidence of temperature-driven behavioural selection in natural systems is lacking. We compared behaviours and behavioural syndromes related to activity, exploration, boldness and aggression in populations of largemouth bass (Micropterus salmoides) from ambient lakes to the those from artificially warmed, power plant cooling lakes to investigate changes in behaviours associated with warmer environments. Activity, exploration, boldness and aggression of juvenile largemouth bass were assessed in laboratory conditions using a novel environment assay and a risky situation assay. We found that activity and exploratory behaviours were higher and decreased through first year ontogeny in populations from heated lakes, whereas these behaviours were lower and showed no relationship through ontogeny in populations from ambient lakes. We attribute these differences to the changes in food source availability in heated lakes associated with temperature-driven ecological effects. Bold and aggressive behaviours tended to differ between populations, as did correlations between behaviours, but did not differ between ambient and heated lakes. The findings of this work identify that large ecological changes associated with warming environments, such as food availability, may drive changes in some aspects of behavioural expression in largemouth bass but that other aspects of behavioural expression may be driven by lake-specific factors not related to warming.     

Interaction of bass tapeworm, Proteocephalus ambloplitis, and Neoechinorhynchus sp. (Acanthocephala) in largemouth bass, Micropterus salmoides

The number of plerocercoids of the bass tapeworm, Proteocephalus ambloplitis, in wild largemouth bass was negatively correlated (r = -0.94) with the number of Neoechinorhynchus sp. Competitive inhibition between the 2 parasites appeared to exist. Similarly, the numbers of Neoechinorhynchus sp. in wild bass decreased when adult bass tapeworms were present in the intestine. Proteocephalus ambloplitis plerocercoids used to challenge bass vaccinated with either P. ambloplitis adult or Neoechinorhynchus sp. antigens were smaller (P less than 0.05) when recovered than those used to challenge control bass. Based on preliminary results, both antigens might have enabled the bass to limit growth and/or development of the invading bass tapeworm, plerocercoids. Cross-protective immunity may be the reason for this occurrence, in which case, it could offer an explanation for competitive inhibition existing between P. ambloplitis and Neoechinorhynchus sp.     

Genetic monogamy and biparental care in an externally fertilizing fish, the largemouth bass (Micropterus salmoides)

Breeding, male North American sunfish (Centrarchidae), are often brightly coloured and promiscuous. However, the largemouth bass (Micropterus salmoides) is sexually monomorphic in appearance and socially monogamous. Unlike some other nest-tending centrarchids in the genus Lepomis, largemouth bass have also been reported to provide biparental care to eggs and fry. Here we use microsatellite markers in order to test whether social monogamy predicts genetic monogamy in the largemouth bass. Offspring were collected from 26 nests each usually guarded by a pair of adults, many of which were also captured. Twenty-three of these progeny cohorts (88%) proved to be composed almost exclusively of full-sibs and were thus the product of monogamous matings. Cuckoldry by males was rare. The genetic data also revealed that some nests contain juveniles that were not the progeny of the guardian female, a finding that can be thought of as low-level 'female cuckoldry'. Overall, however, the data provide what may be the first genetic documentation of near-monogamy and biparental care in a vertebrate with external fertilization.     

Planktivory by bluegill (Lepomis macrochirus) on Leptodora kindti in a small North American lake

Leptodora kindti (Crustacea: Cladocera) is a large species of zooplankton (2–18 mm length) that is exceptionally transparent. This transparency is believed to be a means by which it successfully coexists in lakes with planktivorous fishes. We investigated the gut remains of bluegill (Lepomis macrochirus) that had been feeding on L. kindti and Daphnia (D. galeata and D. retrocurva) in the wild (Lake Zurich, Illinois) and found that bluegill readily preyed on L. kindti as small as 3–5 mm length, and strongly selected L. kindti over Daphnia galeata and Daphnia retrocurva. The large compound eye of L. kindti is one half to one complete order of magnitude larger than Daphnia's eye, consistent with the hypothesis that eye area is an important visual cue for fishes. Moreover, the slope of the relationship between eye area and body length is an order of magnitude shallower in L. kindti than Daphnia, suggesting that eye area has been under stronger negative selection in L. kindti. Results suggest that L. kindti's large and dark eye compromises the transparent nature of its body.     

Population responses of plant-associated invertebrates to foraging by largemouth bass fry (Micropterus salmoides)

The effect of foraging by largemouth bass fry (Micropterus salmoides) upon invertebrates associated with aquatic macrophytes was determined using six 4 m² exclosures in Cochran Lake, Michigan during June 1978. The cladoceranSida crystallina rapidly declined in exclosures with fry, but increased in control exclosures without fry. Chironomids and chydorids showed little change in the exclosures.Invertebrate populations and foraging by fry were also monitored in the lake during 1976 and 1979.Sida declined rapidly in June of both years. In 1979, a decline from 2.2 × 10³ to 0.3 × 10³ individuals per m² and a sharp drop in the proportion of adults between 19 and 22 June coincided with the entry of a large school of fry into the study site on 19 June. Chironomids also declined during June of both years, while chydorids became increasingly abundant in mid-summer and showed no evidence of depletion by the fish.These results suggest that populations of certain prey, which are found locally in high densities in the littoral zone, may be highly susceptible to brief episodes of intense predation by fish fry.     

Mitochondrial genome sequence of the bluegill sunfish (Lepomis macrochirus)

The bluegill sunfish (Lepomis macrochirus) belongs to Lepomis genera of the family Centrarchidae, which is an economically important freshwater species in China. This study presents the complete mitochondrial genome of L. macrochirus, which is the first complete sequence from sunfish species. L. macrochirus mitochondrial DNA is 16,489 bp long, with the genome organization and gene order being identical to that of the typical vertebrate.