Heated competition: how climate change will affect non-native pumpkinseed Lepomis gibbosus and native perch Perca fluviatilis interactions in the U.K

Heated and ambient temperature experimental ponds were used to examine competition between introduced pumpkinseed Lepomis gibbosus and native perch Perca fluviatilis in England, U.K., and how these interactions are likely to change under climate warming conditions. Results from three sets of two-week experiments indicated that in both species and in all sets, growth was faster in heated than in ambient temperature ponds. Growth of both P. fluviatilis and L. gibbosus in sympatry did not differ significantly from that observed in allopatric ponds. Diet analysis indicated that increased resource partitioning occurred when P. fluviatilis and L. gibbosus were reared in sympatry, with P. fluviatilis shifting to a diet higher in microcrustaceans. The results do not support the previous claims of adverse effects of L. gibbosus on P. fluviatilis populations. Under conditions of climate change, however, which have been demonstrated experimentally to enhance L. gibbosus recruitment, this species is expected to become invasive in England, resulting in higher densities that may exert a stronger competitive effect than examined in this study.     

The interactions of abiotic and biotic factors influencing perch Perca fluviatilis and roach Rutilus rutilus populations in small acidified boreal lakes

Four small, acidified boreal lakes, all sustaining populations of perch Perca fluviatilis, roach Rutilus rutilus and pike Esox lucius, were studied in four successive years. Three lakes were moderately acidified (mean pH of 5·61-5·83), while the fourth was more acidic (mean pH of 5·16) and had a sparse population of R. rutilus. Perca fluviatilis density was higher in this lake (1004 ha(-1)) than in the other three (355-717 ha(-1)), where R. rutilus dominated in terms of numbers (981-2185 ha(-1)). Large, potentially predatory, P. fluviatilis were most abundant in the lake with clearest water, and these seemed to have a negative effect on P. fluviatilis density. Perca fluviatilis mean mass was negatively correlated with R. rutilus biomass and was highest in the most acidic lake with the sparse R. rutilus and the highest P. fluviatilis density. Perca fluviatilis mass correlated positively with pH in two lakes (with the highest fish biomass), suggesting that low pH affected P. fluviatilis mass negatively. Perca fluviatilis growth correlated positively with summer (July to August) air temperature in the lake with sparse R. rutilus, thus differing from P. fluviatilis and R. rutilus growth in the other three lakes. The mean age of P. fluviatilis was generally lower than that of R. rutilus and was lowest in the two lakes with the highest fish biomass, indicating that adult mortality was affected by density-induced factors.     

Emergence of the mature trematode Bunodera luciopercae from infected fish under different light conditions

The elimination dynamics of the sexually mature trematode Bunodera luciopercae, a specific parasite of the perch Perca fluviatilis L. was studied using three photoperiods (L: D; L: L; D:D). Permanent illumination induced the helminth to leave fish. The diurnal rhythm of elimination is not pronounced. High values were recorded both in the morning and in the evening. A 40-h elimination rhythm revealed for B. luciopercae is due to certain features of its life cycle.     

Seasonal dynamics in abundance, development and pattern of infection of Bunodera luciopercae (Müller) in perch, Perca fluviatilis L. from an oligotrophic lake in Norway

Samples of perch, Perca fluviatilis L., were examined monthly for the presence of the intestinal trematode Bunodera luciopercae (Müller). Marked seasonal cycles in incidence and intensity of infection were found, with a minimum level in July, when all the fish examined were free of the fluke, and a maximum level in February. Five developmental stages of the fluke were recognized and the seasonal changes in the percentage distribution of these stages were studied. Infective larvae were found in the period August–March, with a peak in January. Gravid worms were mainly found in the period May-June. The frequency distribution of parasite counts were over-dispersed and followed the negative binomial distribution within fish samples from different periods of the year.     

Social learning in young-of-the-year perch encountering a novel food type

Young-of-the-year perch Perca fluviatilis were presented with a novel food type, dry feed, in the presence or absence of demonstrators, who were experienced to the feed. Most inexperienced fish lost mass in the beginning of the study, but untrained fish in the presence of demonstrators already had positive average growth during the first time period. There was a positive correlation between boldness and body mass change. Both social environment and individual characteristics thus seem to affect learning in perch.     

Seasonal changes in the day and night activity of adult perch, Perca fluviatilis L.

Perca fluviatilis L. were caught by gill nets every 3 h over a 24 h period monthly from February 1975 until January 1976. The numbers caught increased with rise in temperature (correlation coefficient r = 0.86 P < 0.001). During the winter months perch migrated into deeper water although some fish were still caught in shallow water (1–6 m). Perch were active at very low light intensities. However changes in visual surface irradiance (400–700 nm) and water clarity caused inverse changes in activity. Only June did not conform to this pattern and it was presumed that spawning behaviour was of primary importance. It is suggested that increase in eutrophication with its effect on water clarity enables fish to become more active during the day in the summer months. They are thus able to utilise food sources to a maximum at an optimum period for feeding and growth.     

Parameterization of European perch Perca fluviatilis length-at-age data using stochastic Gompertz growth models

Three stochastic versions of the Gompertz growth model were used to parameterize total length (L(T) )-at-age data for perch Perca fluviatilis, an important target species for commercial and recreational fishers and a food species for predatory fishes and aquatic birds. Each model addresses growth heterogeneity by incorporating random parameters from a specific positive distribution: Weibull, gamma or log-normal. The modelling outputs for each version of the model provide L(T) distributions for selected ages and percentiles of L(T) at age for both males and females. The results highlight the importance of using a stochastic approach and the logistic-like growth pattern for analysing growth data for P. fluviatilis in Curonian Lagoon (Lithuania). Outputs from this modelling can be extended to a stochastic analysis of fish cohort dynamics, incorporating all length-based biological relationships, and the selectivity-related interactions between fish cohorts and fishing gear.     

Antipredator behaviour of 0+ year Perca fluviatilis: effect of vegetation density and turbidity

In this study, the combined influence of vegetation density and water turbidity on habitat utilization of a prey fish, 0+ year perch Perca fluviatilis , under predation risk (pike, Esox lucius ) was investigated. The vegetated habitat was overall preferred over the open habitat in the presence of a predator. The level of turbidity, and to a lesser extent vegetation density, however, influenced the response of 0+ year perch. The use of the vegetated habitat was lower in very turbid than in clear and turbid conditions, suggesting reduced antipredator behaviour in very turbid water. The effect of vegetation density on antipredator behaviour was only present in clear water, where the use of a structural refuge decreased with increasing vegetation density. No such effect was observed in turbid and very turbid water. The results showed that the structuring role of vegetation or habitat complexity may diminish with increased turbidity. The observed masking effect of turbidity suggests that predator‐prey interactions in vegetated habitats are more complex than what has generally been thought.     

Characteristics of the parasite fauna of the perch Perca fluviatilis L. from the Bolshaya Lindalamba Lake in comparison with other small lakes in Karelia

Parasite fauna of the perch Perca fluviatilis L. is investigated in the Bolshaya Lindalamba Lake, Republic of Karelia. It is shown, that formation of fish parasite fauna in small lakes depends mainly on the type of the lake ecosystem.     

Lethal and 'disturbing' temperatures in some fish species from lakes with normal and artificially elevated temperature

The mean lethal temperatures and 'disturbing' temperatures of 14 species of freshwater fish have been determined in field tests carried out on lakes unheated and heated by power-stations near Konin. The relationships between these parameters and the acclimation temperatures of fish in these lakes are analysed in relation to roach Rutilus rutilus (L.), rudd Scardinius erythrophthalmus (L.) and perch Perca fluviatilis (L.) and compared with the other published data for these species.     

Variation in food intake within groups of juvenile perch

The coefficient of variation of individual food intake was large in small groups of young-of-the-year perch Perca fluviatilis (45–60 mm L _T) and smaller when fish that were given the same feeding rank were placed together. No aggressive interactions were detected during feeding.     

Effect of temperature on proteinase activities of enteral microbiota and intestinal mucosa of fish of different ecological group

Effect of temperature on proteinases activities of enteral microbiota and of intestinal mucosa was studied in five fish species (roach Rutilus rutilus, crucian carp Carassius carassius, common perch Perca fluviatilis, pike-perch Zander lucioperca, and pike Esox lucius) belonging by the nutrition type to different ecological groups. Essential differences of temperature characteristics of proteinases of intestinal mucosa and of enteral microbiota are revealed in fish belonging by the nutrition type to different ecologic groups. The character of the t0-function of proteinases of intestinal mucosa and enteral microbiota by casein and hemoglobin as a rule is different. The highest values of relative proteinases activities for casein in the zone of low temperatures (38 and 45.3 % of the maximal activity) are found at study of proteinases of enteral microbiota in common perch and crucian carp. The latter indicates a significant adaptability of the enteral microbiota proteinases of common perch and crucial carp to functioning at low temperatures.     

Variability of Composition of Microbiota of Gastrointestinal Tract of Perch Perca fluviatilis and Prussian Carp Carassius gibelio During the Vegetative Season

Journal of Ichthyology - The composition of the microbiota of the digestive tract of two fish species differing in feeding habits—perch Perca fluviatilis and Prussian carp Carassius gibelio...     

Individually assessed boldness predicts Perca fluviatilis behaviour in shoals,but is not associated with the capture order or angling method

Selectivity of recreational angling on fish behaviour was studied by examining whether capture order or lure type (natural v. artificial bait) in ice‐fishing could explain behavioural variation among perch Perca fluviatilis individuals. It was also tested if individually assessed personality predicts fish behaviour in groups, in the presence of natural predators. Perca fluviatilis showed individually repeatable behaviour both in individual and in group tests. Capture order, capture method, condition factor or past growth rate did not explain variation in individual behaviour. Individually determined boldness as well as fish size, however, were positively associated with first entrance to the predator zone (i.e. initial risk taking) in group behaviour tests. Individually determined boldness also explained long‐term activity and total time spent in the vicinity of predators in the group. These findings suggest that individual and laboratory‐based boldness tests predict boldness of P. fluviatilis in also ecologically relevant conditions, i.e. in shoals and in the presence of natural predators. The present results, however, also indicate that the above‐mentioned two angling methods may not be selective for certain behavioural types in comparison to each other.     

The effects of temperature and different food organisms on the rate of gastric evacuation in perch (Perca fluviatilis)

SUMMARY. The rate of gastric evacuation in perch Perca fluviatilis was studied at different mean temperatures (range 4.0–21.7°C). Gastric evacuation rates were empirically described by an exponential function and the relationship between the instantaneous evacuation rate ( R ) and temperature was also exponential. Evacuation rates were not significantly different ( P > 0.1) for the following food organisms: Gammarus pulex, Chaoborus , chironomids and zooplankton. The effects of temperature, different food organisms and fish size on the evacuation rates in different fish species are discussed.     

Length and weight changes in 0+ perch, Perca fluviatilis L., following fixation in formalin

Significant shrinkage and increase in weight followed fixation of 0+ freshwater Perca fluviatilis in formalin. Conversion values to obtain live values should take account of formalin concentration, fish size and holding time of preserved fish prior to measurement.     

Amylolytic activity in fish intestinal mucosa: temperature effects

The activity, temperature characteristics and energy of activation of amylolytic enzymes in the intestinal mucosa were studied in six species of fish living in a boreal zone [burbot (Lota lota L.), northern pike (Exos lucius L.), perch (Perca fluviatilis L.), bream (Abramis brama L.), roach (Rutilis rutilis L.), and carp (Cyprinus carpio L.)] and in three species from tropical and subtropical areas [pilchard (Sardina pilchardus W.), jack mackerel (Trachurus trecae C.) and round sardinella (Sardinella aurita V.)]. The amylolytic activity correlated with the feeding habits: it was essentially lower in predators. The enzyme activity at low temperature, relative to the maximal activity, was correlated with the natural environmental temperature where the species lived. At low temperature the relative activity was higher in boreal fish than in tropical and subtropical fish. We found a breakpoint in the Arrhenius plots in all fish species, except for jack mackerel. The energy of activation in predators decreased below the breakpoint in the low-temperature region. The energy of activation in benthophages of the Aral-Ponto-Caspian area was lower at higher temperatures above the breakpoint. A reduction in activation energy in the range of physiological temperatures might indicate adaptation to the environmental temperature.     

Fish community structure in mesotrophic and eutrophic lakes of southern Finland: the relative abundances of percids and cyprinids along a trophic gradient

In 36 south Finnish lakes, the number of species, as well as the cyprinids:percids ratio, was dependent, not only on total phosphorus (TP), but also on lake size. Total fish biomass and cyprinid biomass increased along the TP gradient, whereas the dependence of percid biomass was less evident. Perch Perca fluviatilis and roach Rutilus rutilus strongly dominated mesotrophic lakes; in eutrophic lakes the proportion of other cyprinids and percids, such as white bream Blicca bjoerkna , bream Abramis brama , pikeperch Stizostedion lucioperca and ruffe Gymnocephalus cernuus , increased. Perch biomass was weakly related to abiotic factors but depended on roach biomass. Lake size and fish species composition are essential factors affecting fish community changes in relation to TP, and may be important as well in regulating the responses of a fish community to biomanipulation.     

Temperature dependent characteristics of intestinal glycyl-L-leucine dipeptidase in boreal zone fish

Three kinds of boreal zone fish were investigated for gastrointestinal glycyl-L-leucine (GL) dipeptide cleaving activity as a function of feeding stage and seasonal changes. The enzyme activity tested in the perch (Perca fluviatilis L.) intestine increased steadily during digestion and rapidly disappeared after completion. The temperature characteristics and the seasonal changes in dipeptide cleaving activity in pike perch (Stizostedion lucioperca L.) and bream (Abramis brama L.) were studied. In summer, the maximal activities in the pike perch and the bream were found at temperatures of 40 and 30 degrees C, respectively. In winter, the temperature of maximal activity in pike perch fell to only 30 degrees C, whereas no changes were observed in bream. The activation energies in bream and pike perch were several times lower in winter than in summer. Seasonal changes in the dipeptide cleaving activity at low temperature relative to that at the temperature of maximal activity were found. At high temperatures, the stability of the enzyme decreases in winter and increases in summer, but in the presence of a substrate the thermal stability of the enzyme increases both in winter and in summer. In our experiments, we found that in these fish, GL dipeptidase was unstable at 0 and -10 degrees C.     

Effect of group size on feed intake, growth and feed efficiency of juvenile perch

Feed intake, growth and feed efficiency of juvenile perch Perca fluviatilis were significantly affected by group size, with fish in groups of 12 having lower feed intake, higher growth and higher feed efficiency than solitary individuals. The same trend was seen for fish in groups of 12 compared to fish in groups of four, and for fish in groups of four compared to solitary individuals, although the differences were not always significant. The high growth and low feed efficiency for fish in groups may be caused by benefits obtained from shoaling such as reduced levels of stress.