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.     

A comparison of prey capture kinematics in hatchery and wild Micropterus salmoides floridanus: effects of ontogeny and experience

Analysis of high‐speed videography demonstrated that juvenile wild Florida largemouth bass Micropterus salmoides floridanus captured live prey with very rapid movements and large excursions. Hatchery fish of the same age, raised on pelleted feed, however, used slower kinematics with smaller excursions, yielding strikes with a higher degree of 'suction'. Capture events of hatchery Florida largemouth bass fed live prey for the first time were characterized by movements that had smaller excursion measurements than wild fish and resulted in a decreased level of capture success. After five exposures to elusive mosquitofish Gambusia holbrooki , hatchery Florida largemouth bass adapted their behaviour to capture prey at the kinematic level of wild fish.     

Hunting behavior of Florida largemouth bass, Micropterus salmoides floridanus, in a channelized river

The distribution and behavior of Florida largemouth bass, Micropterus salmoides floridanus, and their main prey (sunfish, genus Lepomis, and the cichlid Tilapia mariae) were studied in southern Florida to determine how fish behave in the simplified habitats found in channelized rivers. Time budgets were constructed from focal animal observations on 69 bass. Patterns of behavior associated with hunting were performed during a significantly higher proportion of the time when bass were in vegetated habitats. Scan samples of the behavior of 236 observed bass revealed that hunting was more common in areas of high structural complexity. Only 38% of observed bass were solitary, with the majority occurring in groups with either conspecifics or in mixed-species groups with similar sized bluegill sunfish, Lepomis macrochirus. Largemouth bass (n=1014) and sunfish (n=1372) were significantly more abundant in areas with vegetation and were almost entirely absent from the water column in the center of the canal. All species of fish avoided the water column, where currents were swift and no cover was available. The structure of the habitat appears to be important in the way largemouth bass organize their activity patterns. This suggests that habitat availability in channelized rivers significantly influences important behaviors such as hunting, thus potentially altering energy budgets and population dynamics of both predator and prey.     

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.     

Isolation and characterization of microsatellite loci for Florida largemouth bass, Micropterus salmoides floridanus, and other micropterids

We isolated and characterized 52 novel microsatellite markers from Florida largemouth bass, Micropterus salmoides floridanus, for use in conservation, management and population genetic studies. Markers were assessed in M. s. floridanus from peninsular Florida (n = 30) and averaged eight alleles per locus with observed heterozygosity of 0.57 (range 0–0.97). Cross‐taxa amplification was successful among 88% of tested congeners. These polymorphic and potentially taxon‐diagnostic markers contribute to the limited number of microsatellites currently available for micropterids and specifically M. s. floridanus.     

Mitochondrial DNA cytochrome b gene variation reveals different largemouth bass genealogies

A mitochondrial DNA character set based on cytochrome b gene variations is described that may be used in conjunction with established nuclear gene differences to assess largemouth bass Micropterus salmoides population structure and dynamics. Alignment of known cytochrome b sequences revealed two regions where the functional constraints of the molecule appear to be sufficiently reduced to allow several amino acid substitutions. Restriction analysis was used to probe nucleotide variation within one of these evolutionary hotspots, resulting in the discovery of fixed largemouth bass subspecific cytochrome b haplotypes. Application of two molecular character sets, one founded on fixed allelic variation in nuclear genes and the other on mtDNA cytochrome b diversity, revealed that in several Texas populations, where the Florida subspecies was introduced into extant populations of northern largemouth bass, hybridization was evident. The direction of the introgression vector could be determined through the combination of both character Sets.     

大口黑鲈微卫星DNA指纹图谱的构建和遗传结构分析

以国内目前养殖的大口黑鲈[Micropterus salmoides(Lacépède)]群体(CH)、2009年引进的佛罗里达亚种(FL-09)、2010年引进的佛罗里达亚种(FL-10)、2010年引进的北方亚种(NT-10)为实验材料,应用43个微卫星DNA标记对这4个大口黑鲈群体进行遗传检测,构建了各群体的微卫星DNA指纹图谱,并对其遗传结构进行分析。结果显示:CH、FL-09、FL-10和NT-10群体的平均等位基因数(A)分别为2.58、3.74、3.70和4.21,平均期望杂合度(He)分别为0.4549、0.4896、0.5010和0.6138,平均多态信息量(PIC)分别为0.3786、0.4443、0.4566和0.5546,表明国内目前养殖的大口黑鲈群体遗传多样性水平远远低于国外新引进的大口黑鲈群体。利用UPGMA法对4个群体进行聚类,结果 FL-09和FL-10聚为一支,遗传距离为0.0506;NT-10和CH聚为另一支,遗传距离为0.4244,推测FL-09和FL-10两个佛罗里达亚种属于相同的群体,而NT-10和CH两个北方亚种来自不同的群体,甚至不同的水系。同时从指纹图谱中,筛选到5个特异的微卫星标记(JZL114、MiSaTPW11、Lma120、Mdo6和Msal21),可以鉴别FL、NT-10和CH群体,其中MiSaTPW11和Msal21这两个标记组合可以完全鉴别这3个群体。将5个特异性微卫星标记的图谱数据转化成计算机可以识别的数码指纹,可以方便应用于大口黑鲈不同群体及其杂交种的鉴定。研究结果可以为我国大口黑鲈种质资源保存、品种鉴定和良种选育提供理论依据。     

Molecular characterization of a ranavirus isolated from largemouth bass Micropterus salmoides.

An iridovirus, isolated from largemouth bass Micropterus salmoides following a die-off among adult fish and provisionally designated largemouth bass virus (LMBV), was characterized by analysis of viral protein synthesis in infected cells, viral DNA restriction fragment length polymorphisms (RFLP), and sequence determination of the major capsid protein and viral DNA methyltransferase genes. All 3 approaches yielded results consistent with the suggestion that LMBV was a member of the genus Ranavirus. Moreover, LMBV was nearly identical to 2 isolates from Southeast Asia which had been previously detected in imported ornamental fish. It remains to be determined whether infection of largemouth bass resulted from exposure to an imported virus, or whether the presence of similar viruses in southeast Asia and the southeastern United States indicates that iridovirus species are not geographically limited as suggested earlier, but rather globally distributed.     

Annual cycles of growth and reproduction in hatchery–reared Florida largemouth bass, Micropterus salmoides floridanus, raised on forage or pelleted diets

Annual cycles of growth and reproduction of hatchery–reared Florida largemouth bass, Micropterus salmoides floridanus , were investigated. Animals were raised on either forage (goldfish, Carassius auratus ) or a pelleted salmon feed. Male and female year–class 1 largemouth bass were sampled throughout one complete yearly cycle (January–December). A biphasic growth cycle was observed in both forage–fed and pellet–fed fish. No increase in body length or weight was observed until approximately midway through the spawning period (May), after which fish grew at a consistent rate for the remainder of the study. The reproductive cycle of forage–fed fish was characterized by a rapid increase in gonadosomatic index (GS1) between January and April, followed by a prolonged spawning period (April–July) during which GSI progressively declined. Fully regressed gonads were observed in September and October, and a resumption of gonadal recrudescence was observed between October and December. Visceral adipose deposits (expressed as mesenteric fat index; MFI) were resorbed during gonadal growth and the initial stages of the spawning period, and restored during the post–spawning phase. Fish raised on pelleted feed had growth and reproductive cycles that parallelled those of forage–fed fish, but several significant differences were observed between the two diet groups. During the growth phase of the cycle, pellet–fed largemouth bass grew significantly faster than forage–fed largemouth bass, and had significantly larger MFIs than forage–fed largemouth bass at all times of the year. Pellet–fed fish also had significantly larger GSIs than forage–fed fish. These data indicate that diet composition may be an important determinant of growth and reproductive function in this species.     

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.     

Experimental trophic ecology of juvenile largemouth bass,Micropterus salmoides,and blue tilapia,Oreochromis aureus

Synopsis The potential for feeding competition between largemouth bass, Micropterus salmoides, and blue tilapia, Oreochromis areus, in Lake Fairfield, Texas was evaluated experimentally. Largemouth bass and blue tilapia were grown in cages alone and in combination with each other. The fish were allowed to feed on the natural food within the lake. Largemouth bass grown in combination with blue tilapia were significantly shorter and weighed less than largemouth bass grown alone. Blue tilapia grown in combination with largemouth bass were statistically significantly longer and heavier than blue tilapia grown alone. Largemouth bass grown alone had diets (volume and number of food items) significantly different than the largemouth bass grown with the blue tilapia. Largemouth bass fed primarily on chironomid larvae and pupae, and odonates, whereas blue tilapia consumed vegetable matter, detritus, and chironomid larvae. Length and weight differences between large-mouth bass grown alone and in combination with blue tilapia, in conjunction with the largemouth bass diet shift, support the theory that these two species compete for food resources.     

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.     

Gene regulatory divergence among species estimated by altered developmental patterns in interspecific hybrids

Disturbances in the schedules of gene expression in developing interspecific fish hybrids have been used to draw inferences about the extent of gene regulatory divergence between species and about the degree to which this gene regulatory divergence is correlated with structural gene divergence, as estimated by genetic distance. Sperm from each of 10 different species representing six genera within the family Centrarchidae was used to fertilize eggs of the Florida largemouth bass (Micropterus salmoides floridanus). The genetic distances (D; Nei 1978) between the parental species used to form the hybrids ranged from 0.133 to 0.974. The developmental success and temporal patterns of gene expression of each of the hybrids were compared with those of the Florida largemouth bass. As the genetic distance between the paternal species and the Florida largemouth bass increased, there was a general decline in developmental success in the hybrid embryos as demonstrated by the observed reductions in the percentage of hatching and by progressively earlier and more extensive morphological abnormalities. Concomitantly, progressively more marked alterations in developmental schedules of expression of 15 enzyme loci occurred in the hybrids as the genetic distance between parental species increased. However, observed deviations from this trend for a few species may represent an uncoupling of the rates and modes of evolution of structural genes from those for genes regulating developmental processes.      

Failure of low-velocity swimming to enhance recovery from exhaustive exercise in largemouth bass (Micropterus salmoides)

This study was intended to discover whether forcing largemouth bass (Micropterus salmoides) to swim at 0.5 body lengths/second following exercise would expedite recovery relative to fish recovered in static water. Exercise resulted in a suite of physiological disturbances for largemouth bass that included a depletion of anaerobic energy stores, an accumulation of lactate, and increased cardiac output. At 1 h following exercise, exhaustively exercised largemouth bass forced to swim exhibited expedited recovery relative to fish in static water, evidenced by lower concentrations of lactate in white muscle, elevated concentrations of phosphocreatine in white muscle, and reduced concentrations of glucose in plasma. By 4 h postexercise, largemouth bass forced to swim during recovery exhibited signs of physiological disturbance that were absent in fish recovered in static water. These signs of disturbance included a loss of osmotically active particles from plasma, elevated lactate in plasma, reductions of phospocreatine in white muscle, and increased cardiac output. These results are discussed in relation to the body of work with salmonid fishes showing physiological benefits to recovering fish in flowing water.     

Proteocephalus ambloplitis and Contracaecum sp. from largemouth bass (Micropterus salmoides) stocked into Boundary Reservoir, Saskatchewan

Nonresident (introduced) largemouth bass (Micropterus salmoides) from Boundary Reservoir, Saskatchewan were examined for helminths. Four species of parasites were found (Diplostomum sp., Proteocephalus ambloplitis, Pomphorhynchus bulbocolli, and Contracaecum sp.). Contracaecum sp. larvae were absent in age-0 and age-1 bass, but prevalence and mean intensity increased with age for bass age-2 or older. Similarly, the prevalence and mean intensity of P. ambloplitis plerocercoids in bass were low until age-2; older bass harbored significantly more plerocercoids. Analysis of stomach contents indicates that this pattern of recruitment for Contracaecum sp. and P. ambloplitis is probably due to increased feeding by largemouth bass on aquatic insects and cannibalism after age-2, respectively. Although Contracaecum sp. may have been established in the reservoir prior to the introduction of bass, we are certain that P. ambloplitis was introduced via stocking with infected fingerlings.     

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.     

Epidemic oral ulceration in largemouth bass (Micropterus salmoides) associated with the leech Myzobdella lugubris

An epidemic of severe ulcerations of the tongue and buccal cavity was documented in subadult and adult largemouth bass (Micropterus salmoides) from Currituck Sound, North Carolina (USA). Other external clinical signs were not present. Between November 1986 and May 1987, reports from fishermen indicated that as many as 90% of large (greater than 300 mm total length) bass were affected. Older fish were the most commonly involved. The leech, Myzobdella lugubris (= Illinobdella moorei), was consistently present on or near the lesions. Lesions were heavily infected with several different bacteria that were apparently secondary invaders. Stressful (high) salinity or an interruption in the normal migratory cycle of the parasite are suggested as possible causes for this condition in these bass.     

The diet of largemouth bass, Micropterus salmoides, in Lake Naivasha, Kenya

Lake Naivasha is a freshwater lake situated in the eastern rift valley of Kenya. Only five species of fish are present, all of which have been introduced. Of these, Oreochromis leucostictus, Tilapia zillii and Micropterus salmoides (largemouth black bass) support an important gillnet fishery with bass also being taken for sport. Until bass reached 260 mm f.l. they depended upon invertebrate food organisms. Thereafter crayfish, fish and frogs became increasingly important the larger the size of the bass. The most important invertebrate prey species was the water boatman, Micronecta scutellaris , followed by chironomid and culicid pupae. Zooplank-ton was consumed but only in large quantity by fish smaller than 80 mm. For bass over 260 mm the crayfish, Procambarus darkii , was the principal food. The largemouth bass in Lake Naivasha are generalized macro-predators, feeding principally on free-living animals of a kind most likely to be found in the littoral zones.     

Correlations of allele frequencies with physical and environmental variables for populations of largemouth bass, Micropterus salmoides (Lacepede)

Differences in the biochemical genetic structure of each of 90 populations of largemouth bass, Micropterus salmoides (Lacepede), were detected by vertical starch gel electrophoresis. The allele frequencies at each of 28 enzyme loci were tested for correlation with 24 physical and environmental variables determined for each body of water from which the populations were sampled. The allele frequencies at several loci (malate dehydrogenase-B, isocitrate dehydrogenase-B, superoxide dismutase-A, and aspartate aminotransferase-B) were highly significantly correlated ( P ≤0.000l) with several physical and environmental variables (latitude, heating degree-days, cooling degree-days, and the length of the growing season). These correlations are consistent with the hypothesis that allelic differences at specific enzyme loci can confer different degrees of fitness in different thermal environments. Additional laboratory and field studies will be required to determine the extent to which allelic variants at a given enzyme locus contribute to thermal tolerance and thermal preference of largemouth bass.