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1.	Almqvist, Gustaf, et al. (författare) Has the invasive round goby caused new links in Baltic food webs? 2010 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 89:1, s. 79-93 Tidskriftsartikel (refereegranskat)abstract The Ponto-Caspian round goby (Neogobius melanostomus, Pallas 1814) most probably was established in the Gulf of GdaA""sk, Baltic Sea, in the late 1980's and has since become one of the dominant species in the region. In this study we assess the role of round gobies as prey for two important fish species in the Gulf of GdaA""sk, cod (Gadus morhua) and perch (Perca fluviatilis). We compared their present diet with stomach analyses from the area prior the round goby establishment, as well as with diet analysis from Baltic regions where round gobies are absent. There were large differences in the diet between cods from the Gulf of GdaA""sk 2003-2006 compared to cods in earlier studies (1977-1981) from the Southern Baltic Sea. There were also large differences in cod and perch diets from areas with and without round goby. Presently, round goby constitutes the most important prey for medium sized cods in Gulf of GdaA""sk, and perch from the same area almost exclusively feed on gobiids. Stomach analysis, trophic level estimates, and stable isotope analyses all indicated that cod and perch in Gulf of GdaA""sk after the round goby establishment belonged to a similar trophic level. Beside round goby, no mussel feeding fish contributed much to the diet of cod or at all to the diet of perch. Thus, it is likely that round gobies constitute a new energetic pathway from mussels to top predators. However, due to the short time elapsed after round goby establishment, we can only speculate on the species future impacts on Baltic food webs.
2.	Amcoff, Mirjam, et al. (författare) A test of sensory exploitation in the swordtail characin (Corynopoma riisei) based on colour matchingbetween female prey and a male ornament 2014 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 97:3, s. 247-254 Tidskriftsartikel (refereegranskat)abstract The sensory exploitation hypothesis states that pre-existing biases in female sensory systems may generate strong selection on male signals to match such biases. As environmental conditions differ between populations, sexual preferences resulting from natural selection are expected to vary as well. The swordtail characin (Corynopoma riisei) is a species in which males carry a flag-like ornament growing from the operculum that has been proposed to function as a prey mimic to attract females. Here, we investigated if female plasticity in feeding preferences is associated with plasticity in preference for an artificial male ornament in this species. Females were trained for 10 days by offering them differently coloured food items and were then tested for changes in preferences for differently coloured artificial male ornaments according to foraging experience. We found a rapid and pronounced change in female preference for the colouration of the artificial ornament according to food training. Thus our results support the possibility that sensory exploitation may act as a driving force for female preferences for male ornaments in this species.
3.	Amcoff, Mirjam, et al. (författare) Multiple male sexual signals and female responsiveness in the swordtail characin, Corynopoma riisei 2015 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 98:7, s. 1731-1740 Tidskriftsartikel (refereegranskat)abstract In the courtship process, multiple signals are often used between the signaller and the receiver. Here we describe female response to multiple male visual morphological and behavioural signals in the swordtail characin, Corynopoma riisei. The swordtail characin is a species in which males display several morphological ornaments as well as a rich courtship repertoire. Our results show that high courtship intensity was associated with an increased female response towards the male ornament, increased number of mating attempts and a reduction in female aggression. The morphological aspects investigated here did not seem to correlate with female response. This may indicate that, when both behaviour and morphology are considered simultaneously, courtship behaviour may have priority over morphological cues in this species.
4.	Backström, Tobias, et al. (författare) Anaesthesia and handling stress effects on pigmentation and monoamines in Arctic charr 2017 Ingår i: Environmental Biology of Fishes. - : Springer. - 0378-1909 .- 1573-5133. ; 100:5, s. 471-480 Tidskriftsartikel (refereegranskat)abstract Stress responsiveness differs between individuals and is often categorized into different stress coping styles. Using these stress coping styles for selection in fish farming could be beneficial, since stress is one main factor affecting welfare. In Arctic charr (Salvelinus alpinus) carotenoid pigmentation is associated with stress responsiveness and stress coping styles. Thus this could be an important tool to use for selection of stress resilient charr. However, anaesthetics seem to affect carotenoid pigmentation, and it would be better if the method for selection could be implemented during normal maintenance, which usually includes anaesthetics. Therefore, this study investigated how the use of anaesthetics affected carotenoid pigmentation, i.e. number of spots, over time compared to no-anaesthetic treatment. Additionally, the stress indicators monoamines and glucocorticoids were investigated. The results indicate that the anaesthetic MS-222 affects number of spots on the right side. This anaesthetic also increased dopaminergic activity in the telencephalon. Both brain dopaminergic and serotonergic activity was associated with spottiness. Further, behaviour during anaesthetization was associated with spots on the left side, but not the right side. Repetition of the same treatment seemed to affect spot numbers on the right side. In conclusion, this study shows that inducing stress in charr affects the carotenoid spots. Thus, it is possible to use anaesthetics when evaluating spottiness although careful planning is needed.
5.	Blom, Eva-Lotta, 1973, et al. (författare) Acoustic and visual courtship traits in two sympatric marine Gobiidae species – Pomatoschistus microps and Pomatoschistus minutus 2016 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 99, s. 999-1007 Tidskriftsartikel (refereegranskat)abstract Divergence in courtship traits across species can evolve as adaptations to different environments, and also through avoidance of reproductive interference and character displacement. Differences may also be explained by phylogenetic relationships. We compared different courtship traits, including male courtship sounds, in two sympatric Pomatoschistus species. Both species are characterised by having male and female courtship, and paternal care of eggs in nests under mussel shells and rocks. In addition to presenting novel observations, we reviewed the literature on courtship traits for both species and complemented it with new observations. We found that courting males of the common goby P. microps sing louder and produce sounds of shorter duration than males of the sand goby P. minutus. Furthermore, males of P. microps swim faster towards females during courtship than males of P. minutus. The eyes of P. minutus females turn black during courtship attempts, whereas this is not the case for females of P. microps. Species-specific differences in courtship sounds and behavior may lead to different susceptibility of the two species to environmental change such as noise pollution and turbidity.
6.	Brodersen, Jakob, et al. (författare) Short-and long term niche segregation and individual specialization of brown trout (Salmo trutta) in species poor Faroese lakes 2012 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 93:3, s. 305-318 Tidskriftsartikel (refereegranskat)abstract Trophic niche divergence is considered to be a major process by which species coexistence is facilitated. When studying niche segregation in lake ecosystems, we tend to view the niche on a one-dimensional pelagic-littoral axis. In reality, however, the niche use may be more complex and individual fidelity to a niche may be variable both between and within populations. In order to study this complexity, relative simple systems with few species are needed. In this paper, we study how competitor presence affects the resource use of brown trout (Salmo trutta) in 11 species-poor Faroese lakes by comparing relative abundance, stable isotope ratios and diet in multiple habitats. In the presence of three-spined sticklebacks (Gasterosteus aculeatus), a higher proportion of the trout population was found in the pelagic habitat, and trout in general relied on a more pelagic diet base as compared to trout living in allopatry or in sympatry with Arctic charr (Salvelinus alpinus). Diet analyses revealed, however, that niche-segregation may be more complex than described on a one-dimensional pelagic-littoral axis. Trout from both littoral and offshore benthic habitats had in the presence of sticklebacks a less benthic diet as compared to trout living in allopatry or in sympatry with charr. Furthermore, we found individual habitat specialization between littoral/benthic and pelagic trout in deep lakes. Hence, our findings indicate that for trout populations interspecific competition can drive shifts in both habitat and niche use, but at the same time they illustrate the complexity of the ecological niche in freshwater ecosystems.
7.	Costalago, David, et al. (författare) Influence of environmental variables on the larval stages of anchovy, Engraulis encrasicolus, and sardine, Sardinops sagax, in Algoa Bay, South Africa 2018 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 101:2, s. 225-236 Tidskriftsartikel (refereegranskat)abstract We investigated the environmental drivers of larval abundance of anchovy Engraulis encrasicolus and sardine Sardinops sagax in Algoa Bay, Eastern Cape (South Africa). This study comprised a pre-drought post-drought time period, comparing the responses of the fish larvae to different factors before and after the drought. The current study presents, for the first time, which environmental variables are affecting the anchovy and sardine larvae populations in the region. Easterly wind speed and zooplankton density were the only environmental variables that presented a significant change between the pre- and post-drought periods, increasing after the drought. Generalized additive models (GAMs) were used in order to explore the effects that environmental factors might have in the abundance of anchovy and sardine larvae in Algoa Bay. Specifically, the GAM that best explained the deviance of the anchovy larvae dynamics included the covariates rainfall, easterly wind speed, Chl a concentration, sardine larvae abundance and the interactions SSTChla and sardSST. The GAM best explaining sardine larvae abundance included only the easterly wind speed as a covariate. This model showed that there was a positive relationship between the higher values of wind speed and sardine larvae abundance.
8.	Cunha, Mario, et al. (författare) The intrinsically dynamic nature of mating patterns and sexual selection 2015 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 98:4, s. 1047-1058 Tidskriftsartikel (refereegranskat)abstract Selection processes are influenced by both biotic and abiotic variables, most of which seasonally fluctuate. Therefore, selection may also vary temporally. Specifically, sexual selection, an integral component of natural selection, will inevitably exhibit temporal variation but the scale at which these changes occur are still not well understood. In this study, performed on a wild population of the sex-role reversed black striped pipefish Syngnathus abaster (Risso, 1827), we contrast variables such as male reproductive success, mating success, female investment, mate choice and operational sex ratio between two periods, either near the onset or end of the breeding season. Sexual selection is stronger early in the breeding season. Male reproductive and mating success are significantly affected by male size during the onset of the breeding season but not during the end. Moreover, we found that larger females reproduce mainly during the onset while smaller females had increased chances of reproducing towards the end. As our sampling was performed in two consecutive years, it could be argued that our results stem primarily from between-year variation. Nevertheless, variation in demographic parameters from the onset to the end of the breeding season is similar to that observed in past sampling events. Hence, we suggest that the change in mating patterns within the breeding season derives from seasonal fluctuations in several abiotic (e.g., temperature) and biotic variables (e.g., operational sex ratio), rendering the expression of selective forces, such as sexual selection, inherently dynamic.
9.	Degerman, E, et al. (författare) Are fish populations in temperate streams affected by crayfish? - A field survey and prospects 2007 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 78:3, s. 231-239 Tidskriftsartikel (refereegranskat)abstract Fish populations may be affected by predation and competition from various types of organisms, among which crayfish have been suggested as important actors. We here present results from stream surveys, suggesting that neither native noble, Astacus astacus, nor introduced signal crayfish, Pacifastacus leniusculus, necessarily affect fish population densities in temperate stream communities. Comparisons of fish densities within stream sites between years with absence and presence of crayfish showed no effect of either crayfish species. A further analysis of changes in fish densities between periods without and with crayfish in low, intermediate and high densities revealed that crayfish density did neither have an effect on fish densities. Our study is one of exceptionally few that consider the above aspects in long-term perspectives in natural systems, and we discuss that previously reported divergent results of cray. sh effects on. sh may be highly dependent on specific species and methods used, and that the effects of cray. sh on. sh populations deserve further attention to enable reliable predictions of community processes in streams.
10.	Enefalk, Åsa, 1972-, et al. (författare) Fine stream wood decreases growth of juvenile brown trout (Salmo trutta) 2019 Ingår i: Environmental Biology of Fishes. - : Springer. - 0378-1909 .- 1573-5133. ; 102:5, s. 759-770 Tidskriftsartikel (refereegranskat)abstract In this study, the growth rate, gut fullness, diet composition and spatial distribution of brown trout was compared between artificial channels with and without fine wood (FW). Access to FW resulted in significantly lower brown trout growth rates over the study period from late summer to early winter as water temperatures declined from 17 °C to 1 °C. Access to FW resulted in minor differences in occurrence of the most common taxa found in brown trout diets, except for chironomid larvae which were found in c. 60% of the brown trout guts from control treatments but in only 30% of the guts from FW treatments in early winter. Diet consisted primarily of case-bearing and free-living Trichoptera larvae, Asellus, chironomid and Ephemeroptera larvae. Brown trout gut fullness was not significantly affected by access to FW bundles. Brown trout aggregated among FW but were more evenly distributed in channels lacking it. Our results suggest that juvenile brown trout use FW as a shelter at a wide range of water temperatures, and that this behaviour may result in reduced growth rates during their first fall and the onset of their first winter. We also show that prey availability and the composition of brown trout diet changes from late summer to early winter and that FW has a small but significant effect on brown trout diet composition.
11.	Engstedt, Olof, et al. (författare) Assessment of natal origin of pike (Esox lucius) in the Baltic Sea using Sr:Ca in otoliths 2010 Ingår i: Environmental Biology Of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 89:3-4, s. 547-555 Konferensbidrag (refereegranskat)abstract Spawning habitat of pike (Esox lucius) in the Baltic Sea include brackish water bays, brooks and rivers. Elevated salinity concentrations are one of several stressors that might increase the use and importance of freshwater habitats for spawning. In the Baltic Sea, one of the largest brackish seas in the world, freshwater species like pike, perch (Perca fluviatilis), whitefish (Coregonus sp), bream (Abramis brama), ide (Leuciscus idus), roach (Rutilus rutilus) and burbot (Lola iota) all undertake spawning migrations to freshwater. However, over the last decades populations densities of these species have declined, and recruitment failure has been argued to be at least part of the problem. The importance of brooks and rivers as spawning areas for these species have not been quantified and set in relation to spawning success in brackish bays. In this study, we collected 175 adult pike (Esox lucius) on their foraging grounds in the sea. Fish were collected in two regions on the Baltic coast, more than 600 km apart. Subsequently we determined their origin (freshwater or marine) using otolith chemistry. Sagittal otoliths were analysed for strontium using the PIXE-method. The results show that 80 of the 175 pike were recruited in freshwater, and several of the larger specimens showed reoccurring migration behaviour. Data show that freshwater is an important recruitment habitat for Baltic Sea pike, suggesting that habitat improvements in rivers entering the Baltic Sea might significantly contribute to population restoration.
12.	Ferrari, Maud C. O., et al. (författare) Effects of turbidity and an invasive waterweed on predation by introduced largemouth bass 2014 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 97:1, s. 79-90 Tidskriftsartikel (refereegranskat)abstract Anthropogenic activities lead to changes in characteristics of aquatic ecosystems, including alteration of turbidity and addition of invasive species. In this study, we tested how changes in turbidity and the recent invasion of an aquatic macrophyte, Egeria densa, may have changed the predation pressure by introduced largemouth bass on juvenile striped bass and delta smelt, two species that have seen a drastic decline in recent decades in the Sacramento-San Joaquin Delta. In a series of mesocosm experiments, we showed that increases in vegetation density decreased the predation success of largemouth bass. When placed in an environment with both open water and vegetated areas, and given a choice to forage on prey associated with either of these habitats, largemouth bass preyed mainly on open water species as opposed to vegetation-associated species, such as juvenile largemouth bass, bluegill or red swamp crayfish. Finally, we showed that turbidity served as cover to open water species and increased the survival of delta smelt, an endemic species at risk. We also found that such open water prey tend not to seek refuge in the vegetation cover, even in the presence of an imminent predation threat. These results provide the beginning of a mechanistic framework to explain how decreases in turbidity and increases in vegetation cover correlate with a decline of open water species in the Sacramento-San Joaquin Delta.
13.	Gerhard, Pedro, et al. (författare) Stream fish communities and their associations to habitat variables in a rain forest reserve in southeastern Brazil. 2004 Ingår i: Environmental Biology of Fishes. - 0378-1909 .- 1573-5133. ; 71:4, s. 321-340 Tidskriftsartikel (refereegranskat)
14.	Gustafsson, Pär, 1973-, et al. (författare) Woody debris and terrestrial invertebrates : effects on prey resourses for brown trout (Salmo trutta) in a boreal stream 2014 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 97:5, s. 529-542 Tidskriftsartikel (refereegranskat)abstract Intensive forestry and other activities that alter riparian vegetation may disrupt the connectivity and the flux of energy between terrestrial and aquatic habitats and have large effects on biota, especially in small streams. We manipulated the amount of in-stream wood and the flux of terrestrial invertebrate subsidies to determine how these factors affected potential food resources for drift-feeding brown trout (Salmo trutta ) in a boreal Swedish forest stream. Specifically, we followed the effects on the abundance of aquatic and terrestrial invertebrate fauna from June to August 2007. The treatments were 1) addition of wood, unmanipulated terrestrial invertebrate inputs, 2) reduction of terrestrial invertebrate inputs (using canopy covers), no addition of wood, 3) unmanipulated ambient conditions, 4) simultaneous addition of wood and reduction of terrestrial invertebrate inputs. Added wood resulted in greater biomass of aquatic invertebrate biomass, and both input and drift of terrestrial invertebrates were reduced by canopy covers. In terms of total potential prey biomass, the addition of wood with ambient levels of terrestrial invertebrate inputs had the highest standing crop of benthic, wood-living and terrestrial invertebrates combined, whereas the treatment with reduced terrestrial input and no wood added had the lowest standing crop. Our study indicates that forest practices that both reduce the recruitment of wood and the input of terrestrial invertebrates to small streams have negative effects on prey availability for drift-feeding brown trout. The positive effects of wood addition on biomass of aquatic macroinvertebrates may partly compensate for the negative effects of reduced terrestrial invertebrate subsidies.
15.	Hart, Paul BJ, et al. (författare) Familiarity with a partner facilitates the movementof drift foraging juvenile grayling (Thymallus thymallus) into a new habitatarea 2014 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 97:5, s. 515-522 Tidskriftsartikel (refereegranskat)abstract Preferring one social partner over another can enhance fitness. This paper reports that juvenile grayling were significantly more likely to enter and forage in new, upstream habitats when paired with familiar versus unfamiliar social partners. Fish paired with unfamiliar partners or when alone were more reluctant to enter the new area. The entry times for both fish in a familiar pair were significantly correlated, but uncorrelated for unfamiliar fish. These differences between familiars and unfamiliars were consistent over a 2-week period. Fish with familiar partners spent more time within three body lengths of each other than did those with unfamiliars. The results are discussed in relation to optimality models of drift foraging, which do not included sociality. It is suggested that the social dimension creates a more dynamic foraging response to variable environmental conditions and could have consequences for growth.
16.	Inogwabini, Bila-Isia (författare) Bushmeat, over-fishing and covariates explaining fish abundance declines in the Central Congo Basin 2014 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 97, s. 787-796 Tidskriftsartikel (refereegranskat)abstract Fish stocks are declining at alarming rates in the Central African forests but little is known about patterns of fishing pressure for different areas. To contribute to the understanding of covariates that could explain these trends, this study documented the relative abundances of fish in eleven sites in the western Democratic Republic of Congo in relation to human density, distance from the nearest markets and mean numbers of fishing nets. Linear regression indicated that, taken alone, 88 % of observed differences in fish relative abundance correlated with the mean number of fishing nets and 60 % of these differences were attributable to distance from the nearest market. Human density was marginally associated with fish abundance. The study also shows that fish and wildlife relative abundances followed the same trends: where more wildlife species remain, there are more abundant fish stocks. The two conservation messages of this paper are that, as is the case for bushmeat, fishing becomes a problem when the commercial market is its prime driver and a solution to the bushmeat crisis could also reduce over-fishing.
17.	Inogwabini, Bila-Isia (författare) Fish species occurrence, estimates and human activities on the islands of the Congo River, Central Africa 2013 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 96, s. 1289-1299 Tidskriftsartikel (refereegranskat)abstract Human induced habitat destruction and modifications cause losses of aquatic and terrestrial biodiversity. The Congo and its islands constitute special ecosystems and have been used by humans for many purposes over centuries. However, little is known about the effects of these human activities on the fish species richness and distribution. This study is a preliminary assessment of island habitat types, fish species richness and effects of human activities on fish distribution. Islands were randomly selected to describe island habitats, to collect fish specimens using nets and to record human activities, including agriculture. Terra firma island habitats were mostly mixed mature forest with clay and muddy substrates. We captured 29 fish morphotypes (13 families). Clariidae and Cyprinidae were widely distributed whereas Alestidae, Chanidae, Malapteridae and Polypteridae were restricted in their distribution. Humans permanently settled 76 % of the islands and 70 % were cultivated. Permanent human settlements and agriculture were related to erosion on similar to 50 % of islands. For reasons that are difficult to explain at this stage, fish morphotype richness decreased with increasing field sizes, warranting further investigations.
18.	Jaric, Ivan, et al. (författare) Insight into Danube sturgeon life history: trace element assessment in pectoral fin rays 2011 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 90:2, s. 171-181 Tidskriftsartikel (refereegranskat)abstract Sturgeon populations in the Danube River have experienced severe decline during the last several decades, mostly due to the poorly regulated fishery, river fragmentation and water pollution. This study focuses on gaining better understanding of sturgeon life history primarily by addressing the assessment of microelement accumulation in sturgeon pectoral fin rays, especially of strontium and calcium, as a method that can reveal migration patterns of anadromous sturgeons. Analysis was performed on pectoral fin samples of three anadromous Danube sturgeon species (beluga, Russian sturgeon and stellate sturgeon) by the use of a Nuclear Microprobe technique. The most frequent pattern in analyzed samples was represented by a low Sr:Ca ratio in the innermost annuli, followed by an increased ratio in the middle annuli segment, and often with a decreased ratio in the outermost annuli. Probability density estimate has revealed three distinguished maxima of the Sr: Ca ratio, 7.08x10(-3), 8.98x10(-3) and 9.90x10(-3), which might correspond, respectively, to fresh, brackish and saltwater. Although the analysis of the Sr: Ca ratio in sturgeon pectoral fin rays has revealed changes that might indicate probable migration between habitats with different water salinity, further studies are needed for improvement of this method. This study represents the first analysis of this kind that was conducted on sturgeon species from the Black Sea basin.
19.	Kolm, Niclas, et al. (författare) Environmental correlates of diet in the swordtail characin (Corynopoma riisei, gill) 2011 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 92:2, s. 159-166 Tidskriftsartikel (refereegranskat)abstract In the sexually dimorphic swordtail characin (Corynopoma riisei, Gill), males are equipped with an opercular flag-ornament that has been suggested to function as a food-mimic since females bite at the ornament during courtship. However, virtually nothing is known about the diet in wild populations of this species. In this study, we first investigated composition of and variation in the diet of C. riisei across 18 different populations in Trinidad, using gut content analyses. We then related variation in gut content to habitat features of populations to investigate the potential link between environmental conditions and prey utilization. Our results showed that the dominating food type in the gut was various terrestrial invertebrates, both adults and larvae, but we also document substantial variation in prey types across populations. Furthermore, a canonical correlation analysis revealed a relationship between environmental characteristics and diet: populations from wider and more rapidly flowing streams with more canopy cover tended to have a diet based more on ants and mosquitoes while populations from narrow and slow flowing streams with little canopy cover tended to have a diet based more on springtails, mites and mayfly larvae. Our results add novel information on the ecology of this interesting fish and suggest the possibility of local adaptation reflecting differences in prey availability across natural populations.
20.	Kolm, Niclas, et al. (författare) Sex-specific territorial behaviour in the Banggai cardinalfish, Pterapogon kauderni 2004 Ingår i: Environmental Biology of Fishes. - 0378-1909 .- 1573-5133. ; 70:4, s. 375-379 Tidskriftsartikel (refereegranskat)abstract In a field experiment, we studied how levels of aggression in males and females in established pairs of the Banggai cardinalfish were influenced by the sex of an experimentally introduced individual larger and more attractive than its resident counterpart. Contrary to previous studies on other cardinalfish species, and contrary to expectations in a sex role reversed species, the male was the main aggressor towards an intruder. Moreover, residents were more aggressive towards an intruder of the same sex as themselves. Furthermore, even though females often courted introduced, larger males, no intruder managed to take over the partnership of any resident. We suggest that our findings imply relatively equal sex roles in the Banggai cardinalfish and we discuss the evolution of sex specific territory defence and its significance in the Banggai cardinalfish as well as the implications of such behaviour in the interpretations of sex roles in general.
21.	Langefors, Åsa (författare) Adaptive and Neutral Genetic Variation and Colonization History of Atlantic Salmon, Salmo salar 2005 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 74:3-4, s. 297-308 Tidskriftsartikel (refereegranskat)abstract I combined neutral microsatellite markers with the major histocompatibility complex (MHC) class IIB to study genetic differentiation and colonization history in Atlantic salmon, Salmo salar, in the Baltic Sea and in the north-eastern Atlantic. Baltic salmon populations have lower levels of microsatellite genetic variation, in terms of heterozygosity and allelic richness than Atlantic populations, confirming earlier findings with other genetic markers, suggesting that the Baltic Sea populations have been exposed to genetic bottlenecks, most likely at a founding event. On the other hand, the level of MHC variation was similar in the Baltic and in the north-eastern Atlantic, indicating that positive balancing selection has increased the level of MHC-variation. Both microsatellite and MHC class IIB genetic variation give strong support to the hypothesis that the Baltic salmon are of a biphyletic origin, the southern population in this study is strongly differentiated from both the northern Baltic salmon populations and from the north-eastern Atlantic populations. Salmon may have colonized the northern Baltic Sea either from the south, via the so called “Närke strait” or from the north, via a proposed historical connection between the White Sea and the northern Baltic. At microsatellites, no significant isolation-by distance was found at either colonization route. At the MHC, populations were significantly isolated by distance when assuming that colonization occurred via the “Närke strait”.
22.	Larsson, Stefan, et al. (författare) Feeding of wild and hatchery reared Atlantic salmon (Salmo salar L.) smolts during downstream migration 2011 Ingår i: Environmental Biology of Fishes. - : Kluwer Journals Online. - 0378-1909 .- 1573-5133. ; 92:3, s. 361-369 Tidskriftsartikel (refereegranskat)abstract In general, hatchery salmonid smolts experience higher mortality during migration than wild smolts, which is suggested to be due to domestication effects and that hatchery fish lack experience of the natural environment. However, possible differences in feeding during smolt migration between hatchery and wild smolts have rarely been addressed. We compared the number of feeding smolts and stomach fullness among wild Atlantic salmon smolts, hatchery-reared smolts released as 1-year-old parr, and hatchery-reared smolts released as 2-year-old smolts during their descent to sea in River Tornionjoki. In addition, estimations of prey selection among the smolt groups were conducted. A high proportion of wild smolts and smolts stocked as parr actively fed during the smolt migration. A lower proportion of smolts stocked as smolts was feeding and their stomach fullness were much reduced in comparison with the two other groups. The study also indicated that the feeding of migrating smolts is selective rather than opportunistic. In conclusion, this study suggests that stocked 2-year-old smolts may enter sea with an inferior foraging behaviour and it is a possibility that this may contribute to the observed low post-smolt survival in the Baltic Sea.
23.	Linløkken, Arne, 1954-, et al. (författare) Environmental correlates of population variables of perch (Perca fluviatilis) in boreal lakes 2008 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 82:4, s. 401-408 Tidskriftsartikel (refereegranskat)abstract We examined relationships among perch population variable parameters in two types of lakes, lakes with perch (P-lakes, n = 15) and lakes with perch and roach (PR-lakes, n = 10) using redundancy analysis (RDA) to relate population variables to environmental factors. Effects from environmental factors were tested for significance by means of permutation tests (Monte Carlo). Three factors, pH, altitude and fraction of roach (by number) in the gill net catches, explaining 47.9% of the variation, had significant effects on perch population variables. The significance of pH was improved by partialing out the effect of conductivity and roach. Similarly, the significance of altitude was improved by partialing out the effect of pH and roach, and the significance of roach was improved by partialing out the effect of pH and altitude. When the fraction of pike in the catch was included in the analysis, the effect of roach was not significant and vice-versa, as roach and pike fractions were correlated with each other. The effect of pike was significant when roach was not included, but the effect was not as strong as the effect of roach. A biplot was constructed by plotting population variables on the first and second RDA axis, with arrows showing five selected environmental factors. Growth of 3+ to 5+ perch was positively related to pH and altitude, perch catch per unit effort was negatively related to pH and altitude, and age specific perch weight was negatively related to fraction of roach. The relationship between growth of 2+ perch and pH was not as strong as the relationship between pH and the growth of older perch. Moreover, the growth of 2+ perch was negatively related to the fraction of roach, probably due to competition between young zooplankton feeding perch and roach.
24.	Lisney, Thomas J., et al. (författare) Ocular dimensions and cone photoreceptor topography in adult Nile Tilapia Oreochromis niloticus 2010 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 88:4, s. 369-376 Tidskriftsartikel (refereegranskat)abstract Information on the anatomy of the eye and the topography of cone photoreceptor cells in the retina is presented for the Nile Tilapia (Oreochromis niloticus). In adults, the shape and proportions of the ocular components of the prominent eye conform to the general form of fish eyes, as determined using cryo-sectioned eyes. The lens is approximately spherical and there is little variation in the distance from the centre of the lens to the border between the choroid and retina at a range of angles about the optical axis. The average ratio of the distance from the centre of the lens to the retina: lens radius (Matthiessen's ratio) is 2.44:1. In retinal wholemounts, single and double (twin) cone photoreceptors, forming a square mosaic, are present. Peak photoreceptor densities for both morphological cone types are found in the temporal retina. Using peak cone densities and estimates of focal length from cryo-sectioned eyes, visual acuity is calculated to be 5.44 cycles per deg. The lack of apparent specific ocular or retinal specializations and the relatively low visual acuity reflect the lifestyle of the Nile Tilapia and may allow it to adapt to changes in visual environment in its highly variable natural habitat as well as contributing to the 'ecological flexibility' of this species.
25.	Lissåker, Maria (författare) Does time of the season influence filial cannibalism in the sand goby, Pomatoschistus minutus? 2007 Ingår i: Environmental Biology of Fishes. - : Springer. - 0378-1909 .- 1573-5133. ; 80:1, s. 69-75 Tidskriftsartikel (refereegranskat)abstract According to life-history theory, filial cannibalism by fish that breed over one season only should be more beneficial early than late in the season if they eat eggs to invest energy into later clutches. Also, filial cannibalism may be more costly late in the season if finding ripe females for replacing eaten eggs is harder then. On the other hand, offspring hatching early may have a competitive advantage over fry hatching late and hence provide higher fitness to the parent. Using data collected over three successive years, I tested if sand goby males are more prone to eat of their eggs early than late in the reproductive season. I found no difference in the amount of eggs eaten or in the frequency of males eating the whole clutch between early and late in the season. Furthermore, there was no difference in the frequency of males who ate parts of their clutches, early compared to late. This might reflect a tradeoff between quality (early hatching offspring) and quantity (producing as many offspring as possible over a long reproductive season). If so, the lack of seasonal pattern of filial cannibalism found in sand gobies might be the result of opposing selection pressures.
26.	Milbrink, Göran, et al. (författare) Long-term effects of nutrient enrichment on the condition and size-structure of an alpine brown trout population 2008 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 81:2, s. 157-170 Tidskriftsartikel (refereegranskat)abstract Long-term effects of nutrient enrichment on a population of brown trout inhabiting a small, alpine lake in north-central Sweden have been studied for nearly 20 years. The study took place between 1981 and 1999 starting up between 1982 and 1987 with full nutrient enrichment of phosphorus and nitrogen in a ratio by weight of 1:8, followed by a period of reduction by half between 1988 and 1994, and thereafter no enrichment at all. Growth of the brown trout population was low before the application of nutrients. Fertilization promoted the development of zooplankton in great abundance, which gave rise to abundant food for the trout. Already during the first year of nutrient addition the average 4+ and 5+ fish had increased in weight by nearly 50% and in length by about 30%. Maximum growth was reached 5-6 years later-weight by about 175% and length by about 50% higher than before application. The slope of the growth curves for fish of ages 2+ to 5+ increased significantly from 1981 to 1987, and so did the size-variation with a high proportion of the fish reaching larger size. After each change in nutrient treatment the mean weights of 5-6-year-old trout were maintained for about 3 years. Five years after termination of fertilization growth was nearly back to the original state. Although badly needed, long-term studies of fish populations like this are few in the literature.
27.	Näslund, Joacim, 1985, et al. (författare) Eggs from anadromous adults provide marine-derived nutrients to Atlantic salmon and brown trout parr in late autumn - observations from a Swedish coastal stream 2015 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 98:12, s. 2305-2313 Tidskriftsartikel (refereegranskat)abstract In this paper we demonstrate that eggs from anadromous salmonines can constitute a large proportion of the dietary intake of individual juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta during the spawning period in late autumn. The majority of fish older than 1 year residing on a spawning ground were found to have ingested eggs from spawning salmonines (Salmo sp.). Young-of-the-year brown trout were also able to consume eggs, at least down to a minimum fork length of 68 mm. The smallest Atlantic salmon found to have consumed eggs had a fork length of 79 mm. Larger fish were more likely to consume eggs, and consumed more eggs, than smaller individuals. The eggs of anadromous salmonines provide a rich source of marine-derived nutrients to the freshwater residing juveniles at the onset of winter. Our study highlights that these eggs may constitute an important energy input for juvenile salmonines in European anadromous populations, and could possibly influence winter survival rates and subsequent smoltification in the following spring.
28.	Näslund, Joacim, 1985, et al. (författare) Fish density, but not environmental enrichment, affects the size of cerebellum in the brain of juvenile hatchery-reared Atlantic salmon 2019 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 102, s. 705-712 Tidskriftsartikel (refereegranskat)abstract This paper describes a study on the environmentally dependent brain size plasticity in hatchery-reared Atlantic salmon Salmo salar L. Using a factorial experimental design, we tested whether tank fish density, local hatchery standard (150 fish ∙ m −2 ) vs. reduced (50 fish ∙ m −2 ) and structural enrichment, a bundle of submerged plastic stripes, had effects on the size of the cerebellar region of the brain. Fish reared at reduced density had smaller cerebella, while structural enrichment had no detectable effects. The density effect on cerebellum, which is involved in locomotion and cognition, confirms previous results from hatchery-reared Atlantic salmon. The lack of detectable positive effects of enrichment, which contrasts some previous studies, provide further evidence for a complex relationship between environmental complexity and brain growth.
29.	Ovegård, Mikael, et al. (författare) Previously undocumented relationship between spiny dogfish Squalus acanthias and juvenile Atlantic horse mackerel Trachurus trachurus revealed by stereo-BRUV 2022 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 105, s. 453-458 Tidskriftsartikel (refereegranskat)abstract This study revealed a previously undocumented association between a teleost and a shark. Atlantic horse mackerel Trachurus trachurus were observed following spiny dogfish Squalus acanthias during 3 consecutive years (2018-2020) on off-shore banks in Kattegat (57 degrees N; 11 degrees E, Sweden). The observations were made by the use of stereo-BRUV (baited remote underwater stereo-video systems). Our findings provide additional information about relationships between sharks and teleosts and suggest that stereo-BRUV can add to the ecological knowledge gained from the commonly deployed trawl surveys in temperate waters such as the Kattegat. With the increasing use of BRUVs in areas where the method has rarely been used before, such as higher latitudes or deeper water, observations as the one described here will likely increase. We urge the growing community of BRUVvers to make use of the methods full potential and to share not only estimations of abundance of different species but also observations of species associations and behaviors. These observations are important for better understanding of the interaction between species and could be important knowledge for targeted management measures.
30.	Petersson, Erik, et al. (författare) Failed protective effort of ex situ conservation of River Vistula trout (Salmo trutta) in Sweden 2022 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 105, s. 1099-1109 Tidskriftsartikel (refereegranskat)abstract Ex situ conservation comprises some of the oldest and best-known conservation methods and it has been applied for different fish stocks. This study describes attempts undertaken to preserve the long-migrating River Vistula (Poland) brown trout by a sea-ranching programme in the River Dalalven (Sweden). This focal strain was threatened in its native river and a major reason for selecting the River Dalalven was that its river mouth faces north as does that of the River Vistula. In the Swedish river, the Vistula trout in the 1970s and early 1980s returned early in the autumn and were generally large-sized (compared to the native strain of the River Dalalven). Over the study period (1978-2012), the size of returning adult fish declined, the return date becoming later in the year, and the number of spawners also declined. The reasons for these changes were probably caused by several interacting factors: (1) the most likely being high mortality of early returning fish which were held for longest in captivity before being used in the artificial spawning process; (2) the fact that the hatchery process was adapted to the Dalalven strain and not the Vistula one; (3) that the Vistula fish were marked by removing both pelvic fins (possible reducing subsequent survival); and (4) low genetic variation (as a result of few returning individuals). Thus, for several reasons, this ex situ conservation attempt for Vistula trout in Sweden is thought to have failed.
31.	Piccolo, John J, et al. (författare) Food and space revisited: The role of drift-feeding theory in predicting the distribution, growth, and abundance of stream salmonids 2014 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 97, s. 475-488 Tidskriftsartikel (refereegranskat)
32.	Piccolo, John J., 1964-, et al. (författare) Preface to the special drift foraging issue of Environmental Biology of Fishes 2014 Ingår i: Environmental Biology of Fishes. - New York : Springer. - 0378-1909 .- 1573-5133. ; 97:5, s. 449-451 Tidskriftsartikel (refereegranskat)
33.	Robinson-Wolrath, Sarah (författare) Video Playback Versus Live Stimuli for Assessing Mate Choice in a Pipefish 2006 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 75:4, s. 409-414 Tidskriftsartikel (refereegranskat)abstract In this study, I investigated the application of the video playback technique to studies on mate choice in the pipefish, Syngnathus typhle. In this sex-role reversed species, the males are predominately the choosing sex, and given a choice, prefer to mate with larger females. As such, I tested if this known mate preference remained when using this novel experimental technique. Specifically, I compared the response of males to video images of females to that of live females. Results revealed that male pipefish showed a stronger preference for the larger female in the video playback treatment than in the clear glass (two-way interaction) live female treatment. This experiment has, therefore, demonstrated that the pipefish respond in the predicted direction in response to video playback, and as such proves to be a reliable method to study mate preferences in this species.
34.	Scharnweber, Kristin, 1983-, et al. (författare) Feeding efficiency and food competition in coexisting sexual and asexual livebearing fishes of the genus Poecilia 2011 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 90:2, s. 197-205 Tidskriftsartikel (refereegranskat)abstract Considering its immediate costs of producing dispensable males, the maintenance of sexual reproduction is a major paradox in evolutionary biology. Asexual lineages that do not face such costs theoretically should replace sexuals over time. Nonetheless, several systems are known in which closely related sexual and asexual lineages stably coexist. In the present study, we studied a sexual/asexual mating complex of a sperm-dependent parthenogenetic fish (amazon molly, Poecilia formosa) and its sexual congeners, the sailfin molly P. latipinna and the Atlantic molly P. mexicana. We asked whether differences in feeding behavior could contribute to their stable coexistence. We conducted a laboratory experiment to compare feeding efficiencies and also measured the competitive abilities between the two reproductive forms. Additionally, we measured gut fullness of fishes caught in natural habitats. Contrary to our predictions, we could not find P. formosa to be less efficient in feeding. We argue that food competition in mollies plays a minor role in mediating coexistence between closely related asexual and sexual mollies.
35.	Svedang, H., et al. (författare) Migratory behaviour and otolith chemistry suggest fine-scale sub-population structure within a genetically homogenous Atlantic Cod population 2010 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 89:3-4, s. 383-397 Tidskriftsartikel (refereegranskat)abstract The question whether temperate marine fishes typically consist of self-sustaining populations or "open" populations still remains unresolved. At the heart of this population connectivity problem lays the nature of the stock separation mechanisms. Fish populations could be segregated either by environmental forcing, accompanied with opportunistic recruitment of juveniles to spawning areas, or by philopatric behaviours (i.e., inclination of an individual to return to or remain in its natal area). Here we report three, partly independent, studies on Atlantic Cod (Gadus morhua) stock separation in the Kattegat and Oresund (eastern North Sea): characterisation of spawning aggregations with genetic markers, tagging experiments, and analysis of chemical constituents in otolith cores of recaptured fish that could be linked to a specific spawning site. While the genetic investigation showed no population segregation, the observed migratory patterns indicated three separate spawning sites at close distances. The natal dependence on the choice of spawning site was tested by measuring the contents of various trace elements in the otolith core of recaptured tagged fish. Quantification of the trace elements: Ba, Br, Co, Cr, Cu, Fe, Mn, Mo, Ni, Sr, Ti, and Zn expressed as ratios to Ca were obtained using scanning micro PIXE. These results indicated that natal origin could be differentiated between spawning sites, supporting the hypothesis that natal homing is an important stock separating mechanism even over short distances (<100 km).
36.	Vincent, Amanda C.J., et al. (författare) Reproductive ecology of five pipefish species in one eelgrass meadow 1995 Ingår i: Environmental Biology of Fishes. - : Kluwer Academic Publ. - 0378-1909 .- 1573-5133. ; 44:4, s. 347-361 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Synopsis Pipefishes have rarely been watched in the wild and have never before been followed in their common seagrass habitats. This study explores the reproductive ecology of five species of pipefishes living in a Swedish eelgrass meadow during parts of four breeding seasons, tagging four of the species. Pipefish are remarkable for their specialised paternal care: only males aerate, osmoregulate and nourish the developing embryos. Two of the species (Entelurus aequoreus andNerophis ophidion) have simple ventral gluing of eggs on the trunk while three species (Syngnathus acus, S. rostellatus andS. typhle) have fully enclosed brood pouches on their tails. Males of the former species receive eggs from one female while males of the genusSyngnathus receive partial clutches from several females. Sex ratios of adults on the site differed from equal to male-biased to female-biased, according to species.S. typhle were most numerous and were resighted most often. They were present throughout the breeding season whereas there were temporal shifts in the presence of the other species on the meadow and in some sex ratios. Most species occurred in the deeper, denser part of the meadow but there was some habitat separation by species and sex. All species tended to stay low in the eelgrass, primarily coming up above the eelgrass to display and mate. No species showed site fidelity either to a home range or to the meadow, withE. aequoreus adults spending least time on the meadow. Sexual size dimorphism differed: males were larger inS. rostellatus, the same size inS acus and smaller in the other species. Although the species overlap in habitat requirements and breeding season, the only observed interspecific interactions were abortive courtships betweenSyngnathus species.
37.	Watz, Johan, 1977-, et al. (författare) Day and night drift-feeding by juvenile salmonids at low water temperatures 2014 Ingår i: Environmental Biology of Fishes. - : Springer Netherlands. - 0378-1909 .- 1573-5133. ; 97:5, s. 505-513 Tidskriftsartikel (refereegranskat)abstract Drift-feeding salmonids in boreal streams face temperatures below physical optima for extensive periods of the year. Because juvenile salmonids react to low water temperatures by becoming nocturnal, knowledge about their foraging ability at low light intensities in cold water is needed to accurately estimate energy intake during non-summer conditions. In a laboratory stream channel, we studied temperature effects on the drift-feeding behaviour of juvenile Atlantic salmon, brown trout, and European grayling in simulated daylight and moonlight at temperatures ranging from 2 °C to 11 °C. Prey capture probability was positively related to temperature, but the temperature dependence did not agree with predictions of the Metabolic Theory of Ecology. Furthermore, reaction distance was positively related to temperature for the three species, which may be one of the underlying mechanisms responsible for the temperature effects on prey capture probability. Overall, the three species had similar capture rates at the different temperature and light levels, although there were species differences. European grayling had a slightly higher prey capture probability than brown trout, and brown trout had a shorter reaction distance than Atlantic salmon and European grayling. These results have implications for both energetics-based drift-foraging theory and for studies of winter ecology.
38.	Westerberg, Håkan (författare) Larval size-distributions of Ariosoma balearicum cryptic species during the March-April season in the Sargasso Sea Subtropical Convergence Zone 2019 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 102, s. 1231-1252 Tidskriftsartikel (refereegranskat)abstract Leptocephali of the shallow-water congrid eel Ariosoma balearicum are abundant during February-April in the Sargasso Sea, and larval and adult meristic data indicates this species includes several regional subpopulations/cryptic species. Four multiple-transect larval surveys (2011, 2014, 2015, 2017) were used to examine the geographic size distribution of two myomere-count types of A. balearicum leptocephali. High-count (HC) larvae were consistently mostly between 80 and 100 mm in size (60-132 mm; 87.9 +/- 6.8 mm) as observed previously, and frequently had narrow size ranges. The usually larger LC larvae (78-176 mm; 111.4 +/- 26.7 mm) were more abundant in western or central areas. HC larvae tended to decrease in size from west to east and increase from south to north. Catch rates were geographically variable relative to hydrographic structure/frontal positions across the wide 2015 sampling area. Mitochondrial 16 s rRNA sequences of HC and LC larvae show species-level differences, providing evidence of the existence of two cryptic species with different larval dispersal strategies in the Sargasso Sea subtropical gyre region. The HC larvae disperse widely into the gyre, seemingly through Gulf Stream recirculation or eastward frontal-jet flows, and apparently must use directional swimming to cross the Florida Current to recruit into the South Atlantic Bight. LC leptocephali may mostly be retained near the Bahamas, with few larvae dispersing into the gyre. This seems to indicate natural selection occurred for spawning location and larval behavior due to the powerful Florida Current/Gulf Stream, resulting in two completely different spawning and larval dispersal strategies within a local geographic region.
39.	Öhman, Marcus C., et al. (författare) Relationships between habitat structure and fish communities on coral and sandstone reefs 1998 Ingår i: Environmental Biology of Fishes. - 0378-1909 .- 1573-5133. ; 53, s. 19-31 Tidskriftsartikel (refereegranskat)abstract The influence of habitat structure on reef-fish communities at Bar Reef Marine Sanctuary, Sri Lanka, was investigated. The relationship between habitat characteristics and the distribution and abundance och 135 species of fishes was examined on two reef types: coral and sandstone reefs. Results suggested that the reef fish communities were strongly influenced by various aspects of reef structure. However, relationships between habitat variables and fish communities structure, varied between the two reef types. Fish species diversity was correlated with a number of habitat variables on the sandstone reefs, although structural complexity seemed to play the dominant role. There were no correlations between habitat structure and fish diversity on the coral reefs. Total abundance was not related to any one habitat parameter on either reef type. However, abundances of some species, families and trophic groups were correlated with habitat features. These specific correlations were commonly related to food and shelter availability. For example, coral feeders were correlated with live coral cover, and pomacentrid species, which used branching corals for protection, showed a significant relationship with the density of Acropora colonies. This shows that a summary statistic such as total abundance may hide important information. Effects of habitat structure on the distribution patterns of the fish communities was further investigated using multidimensional scaling ordination and the RELATE-procedure. With the MDS-ordinations for both habitat and fish community composition it was possible to show that the multivariate pattern between the two ecological components was clearly correlated.
40.	Bergman, Kajsa C, et al. (författare) The influence of habitat structure on the abundance of Pomacentrus sulfureus, a western Indian Ocean reef fish 2000 Ingår i: Environmental biology of fishes. - 0378-1909. ; 59:3, s. 243-252 Tidskriftsartikel (refereegranskat)
41.	Hammar, J, et al. (författare) Why do juvenile fourhorn sculpin, Triglopsis quadricornis, appear in the pelagic habitat at night? 1996 Ingår i: ENVIRONMENTAL BIOLOGY OF FISHES. - : KLUWER ACADEMIC PUBL. - 0378-1909. ; 46:2, s. 185-195 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Challenging the generally accepted view of the fourhorn sculpin Triglopsis quadricornis as a cold-stenothermal and true benthic species, novel findings of juveniles in the pelagic habitat of Lake Vattern, Sweden, have been examined and critically evaluate
42.	KVARNEMO, C (författare) SIZE-ASSORTATIVE NEST CHOICE IN THE ABSENCE OF COMPETITION IN MALES OF THE SAND GOBY, POMATOSCHISTUS-MINUTUS 1995 Ingår i: ENVIRONMENTAL BIOLOGY OF FISHES. - : KLUWER ACADEMIC PUBL. - 0378-1909. ; 43:3, s. 233-239 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Size-assortative choice of nest site is commonly found among fish with paternal care. This pattern can be explained either by the superior competitive ability of large males for preferred large nests, or by a choice of nest size that is related to the mal
43.	Pettersson, Lars, et al. (författare) The diel activity of crucian carp, Carassius carassius, in relation to chemical cues from predators 2001 Ingår i: Environmental Biology of Fishes. - 0378-1909. ; 61:3, s. 341-345 Tidskriftsartikel (refereegranskat)abstract Chemical cues from piscivorous fish and prey alarm substances often cause rapid fright responses in prey. However little is known of how piscivore-related chemical cues affect prey behaviour over periods longer than a few hours. Here we have investigated how chemical cues from piscivorous northern pike, Esox lucius, affect habitat choice and diel activity of crucian carp, Carassius carassius, over an extended period 11 days. At the beginning of the experiment control fish were nocturnal while fish in the pike cue treatment were aperiodic. After 11 days, control fish had become more strongly nocturnal and displayed two activity peaks during early and late night whereas fish in the pike cue treatment were still aperiodic with no activity peaks. Habitat choice was aperiodic in both treatments throughout the experiment. In both treatments, more fish were found in the vegetation zone than in the open habitat. This was most pronounced when pike cues were present. These results demonstrate that short-term anti-predator responses to chemical cues from predators can translate into long-term adjustments of diel periodicity. Further, the results did not support the idea that crucian carp should switch to nocturnal activity in response to visually hunting predators. Control fish were nocturnal and chemical cues from pike did not make this pattern more pronounced.

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