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1.
Abstract – The aquatic environment is being perturbed globally through increases in turbidity, which can have detrimental effects for the maintenance of fish diversity, especially in species dependent on visual cues for reproduction and species recognition. We performed a short‐term manipulation of the visual environment in Lake Malawi to test for an immediate behavioural response to increased turbidity in territorial rock‐dwelling cichlid fishes that use colourful visual cues to maintain territories near the substrate and attract mates. We found a significant movement of fish away from the substrate, with a concomitant shift from displaying territorial and courting behaviours to foraging behaviours, during the five minutes following the release of a turbidity plume over the area. This study is the first to test for and demonstrate an immediate behavioural response of a natural fish population to a short‐term increase in turbidity that might mimic the initial (i.e., immediate) stage of a run‐off event after rainfall in a deforested area. 相似文献
2.
Michael J. Pauers Joshua M. Kapfer Kirsten Doehler J. Todd Lee Craig S. Berg 《Ecology of Freshwater Fish》2012,21(1):34-41
Abstract – The role of male colouration in the behavioural interactions of haplochromine cichlids has received much attention. Previous studies supported the role played by visual signals during interactions of rock‐dwelling cichlids, or mbuna, from Lake Malawi. It has largely been assumed that hue, and not pattern, is the primary signal encoded in male colouration; thus, the role of colour pattern has received less attention. We explored the use of visual signals during aggression in Labeotropheus fuelleborni by using identically and differently coloured opponents and by offering these opponents under coloured illumination. We presented two simultaneous opponents to males and found that the focal male’s responses depended upon opponent colour pattern; similarly patterned opponents received more aggression, even if presented under a hue‐obscuring light source. These results support findings that gross colour pattern may be more important than hue in interactions among the mbuna and further support an important role for visual communication in these fishes. 相似文献
3.
Masaki Kawakami Richard Zatha Bosco Rusuwa Atsushi Maruyama 《Ecology of Freshwater Fish》2019,28(2):247-256
Cichlid fishes in the rocky littoral zones of Lake Malawi are among the most diverse endemic fish communities of the world. They segregate food resources, but considerable niche overlaps have been reported by numerous studies in this field. If their niches largely overlap, the heterospecific individuals are expected to behave like conspecific individuals. Instead of studying their niche segregation, we investigated the spatial distribution patterns of adult males of nine abundant cichlid species by point process analysis, with due attention to niche partitioning, as measured by stable isotope analysis. Because their feeding habitats are restricted by intra‐ and interspecific interferences over the mating and feeding territories respectively, we hypothesised that the interspecific feeding territories of species with nearly similar niche tended to be distributed uniformly. Although the typical territorial animals are expected to be distributed uniformly, the distribution pattern of intraspecific mating territory was judged to be uniform only for two out of nine species. This result suggests that each species has its specific preference for territorial locations or their locations are restricted by interspecific interactions. The latter explanation was partially supported by the agreed locations of gravity centres between intraspecific mating and interspecific feeding territories. Species pairs with similar isotope ratios tended to show a uniform distribution of interspecific feeding territories. Thus, individual species pairs keep a certain distance from each other by using nearly similar food resources. This result suggests that some cichlid species coexist not only through niche segregation but also through territorial interactions, like conspecific individuals. 相似文献
4.
Montaña CG, Winemiller KO. Local‐scale habitat influences morphological diversity of species assemblages of cichlid fishes in a tropical floodplain river.Ecology of Freshwater Fish 2010: 19: 216–227. © 2010 John Wiley & Sons A/S Abstract – We examined the taxonomic and morphological diversity of cichlid fish assemblages in a floodplain river in Venezuela during the dry season at two spatial scales: macrohabitats (lagoons, main channels and creeks) and mesohabitats (leaf litter, sand banks, rocky shoals and woody debris). Nonmetric multidimensional scaling did not reveal differences for species assemblages among macro and mesohabitats. The first two axes from canonical correspondence analysis based on 19 species and six physical variables modelled >61% of the taxonomic variation in assemblages from rock shoals and woody debris, and 55% of variation in assemblages from sand banks and leaf litter. Principal components analysis based on 22 morphological variables yielded two dominant axes that explained >86% of variation in the cichlid assemblages. Morphological diversity was analysed to test the idea that assemblage structure is nonrandom, with structurally complex habitats supporting more species with more functional morphological diversity than simple habitats. Average and standard deviation (SD) of the morphological Euclidean distances of local assemblages among mesohabitats tended to decrease or be constant as the number of species increased. Regressions of the average nearest neighbour distance (NND) and SD of NND with species richness resulted in low and negative slopes of species assemblages among mesohabitats. These relationships suggest that when more species are added to a habitat patch, assemblage morphospace remains approximately constant, species average similarity increases and species dispersion in morphological space becomes more uniform. Results support that cichlids partition habitat at the local scale but not at the macrohabitat scale. 相似文献
5.
Ronald George Oldfield 《Fish and Fisheries》2005,6(2):93-110
Genetic and environmental factors may interact to control sex determination in fishes. A common pattern of initial female differentiation and subsequent male transformation before maturation in non‐hermaphroditic fishes and after maturation in sequentially hermaphroditic fishes has suggested that changes in developmental timing may be responsible for the evolution of various expressions of sexual lability. Sequential hermaphroditism is rare in freshwater fishes, but investigators report degrees of sexual lability at four distinct life stages in cichlid fishes. Some cichlids undergo genetic sex determination and are not labile. Lability at the larval stage allows temperature or pH to determine sex. Social interactions apparently determine sex at the juvenile stage in the Midas cichlid (Amphilophus citrinellus). Most reports of post‐maturational sex change in cichlids are anecdotal or unsubstantiated. The common occurrence of same‐sex spawning suggests that many species are incapable of sex change. Sequential hermaphroditism is concluded not to be typical, except for the checkerboard cichlid (Crenicara punctulata), which regularly undergoes functional female‐to‐male transformation. Expression of sexual lability at four life stages in one family of fishes corroborates a role for developmental timing in the evolution of sequential hermaphroditism as well as environmentally controlled sex determination. The broad phylogenetic distribution of sexual lability in cichlids indicates that processes capable of producing sex change are generally present. The rarity of sequential hermaphroditism in cichlids and possibly other freshwater fishes is likely due to unpredictability of food and therefore potential mate distributions compared with coral reef habitats. 相似文献
6.
New statistical developments combined with the use of highly polymorphic microsatellite DNA markers enable the determination of the population of origin of single fish, resulting in numerous new research possibilities and applications in practical management of fish populations. We first describe three main categories of methods available, i.e. (i) assignment tests and related methods, (ii) discriminant function analysis and (iii) artificial neural networks. In all these, individuals can be assigned to the population from which their multilocus genotypes are most likely to be derived. Assignment tests are based on calculations of the likelihood of multilocus genotypes in populations, based on allele frequencies. Discriminant function analysis is based on multivariate statistics, whereas artificial neural networks formulate predictions through exposure to correct solutions. Assignment tests are the methods of choice when considering genetic data alone, whereas discriminant function analysis and artificial neural networks may be useful when genetic data are combined with, for instance, morphological and ecological data. Assignment tests can be used to assess the genetic distinctness of populations, for discriminating among closely related species and to directly identify immigrants or individuals of immigrant ancestry, and thereby study patterns of dispersal among populations, including sex‐biased dispersal. In a conservation context, assignment tests can be used to assess the genetic impact of domesticated fish on wild populations and for determining if extant fish populations are in fact indigenous or descendants from stocked fish or strayers, and they can be applied in forensics, for instance to reveal poaching. Assignment tests are at present most useful for studies of freshwater and anadromous fishes owing to stronger genetic differentiation among populations than in marine fishes. However, some genetically divergent populations of marine fishes have been discovered, which could be used as natural laboratories for studying dispersal and gene flow. It is foreseen that ongoing developments in statistical methods, combined with improved techniques for screening large numbers of loci, will permit assignment methods to become standard tools in studies on the biology of fishes. 相似文献
7.
Md Rakeb‐Ul Islam Daniel J. Schmidt David A. Crook Jane M. Hughes 《Ecology of Freshwater Fish》2019,28(2):229-240
A comprehensive knowledge of migratory behaviour is paramount for the effective management and conservation of fishes in coastal drainages. The Australian smelt (Retropinna semoni) is a common fish distributed throughout coastal and inland drainages in south‐eastern Australia. Multiple life history patterns (potamodromy, facultative diadromy, estuarine residence) in the southern regions of its geographic distribution have been reported, and it is possible that some of these differences reflect characteristic behaviours of cryptic species within the group. To elucidate the life history patterns of smelt at the northern extent of their range and to identify any differences in migratory behaviour between two genetically distinct lineages (“SEQ‐N”, “SEQ‐S”) in this region, the movement patterns of Australian smelt were assessed using otolith chemistry. No evidence of marine residence was found based on otolith Sr:Ca and Ba:Ca transects for either group, suggesting that both are non‐diadromous. Significant differences in multi‐elemental otolith chemistry signatures were found among rivers and between paired sites within some rivers, suggesting no connectivity among drainages and limited dispersal of individuals over large spatial scales within rivers. These findings provide key insights into the migratory patterns of northern Australian smelt populations and, in combination with previous research, suggest that life history variation in the Australian smelt complex may occur primarily at the intra‐population level rather than among genetically distinct lineages. Conservation and management strategies for Australian smelt should take limited dispersal and individual life history variation into consideration in order to protect the components of this important species complex. 相似文献
8.
OLIVER BERRY PHILLIP ENGLAND DAVID FAIRCLOUGH GARY JACKSON JIM GREENWOOD 《Fisheries Oceanography》2012,21(4):243-254
Determining the extent of dispersal in exploited marine fishes is essential for understanding their population dynamics and optimising management. The West Australian dhufish, Glaucosoma hebraicum, is a highly sought‐after, large and long‐lived reef‐dwelling species, endemic to south‐western Australia. Stock assessments indicate that this indicator species is overexploited. The fishery is managed using a zone‐based system, which implicitly assumes a high degree of demographic independence among zones. While tagging studies indicate limited movement of adult G. hebraicum, there is no understanding of the spatial scale of dispersal of its larvae and thus the true extent of interdependence of management zones. We analysed 13 microsatellite DNA loci to characterise the extent of gene flow, and conducted particle tracking simulations to model larval transport in this species. Genetic data demonstrated that some local recruitment was likely, but that on a broad scale gene flow between the management zones was extensive, and the entire fishery represents a single genetic stock. Hydrodynamic modelling predicted that the majority of dhufish larvae recruit from within the management zone where they are spawned, and that inter‐annual variation in current velocities has limited effect on the extent of larval transport. Because management zones are likely to be largely independent in terms of both larval and adult recruitment, heavy localised fishing pressure has the potential to reduce the abundance and reproductive capacity of this species in highly fished areas, but it should have limited impact on neutral genetic diversity. 相似文献
9.
William L. Stacy‐Duffy Sara M. Thomas David H. Wahl Sergiusz J. Czesny 《Fisheries Management and Ecology》2020,27(4):303-313
Variation in the distribution and abundance of nearshore fishes is critical to understand food web processes and fishery management issues in Lake Michigan. This study characterised patterns in abundance of three common nearshore species, yellow perch Perca flavescens (Mitchell), round goby Neogobius melanostomus (Pallas) and alewife Alosa pseudoharengus (Wilson), in relation to spatio‐temporal, abiotic and biotic factors using gillnet sampling conducted across 5 years at multiple locations representing different substrates. Significant variations were observed in alewife and round goby catches between locations. A negative relationship between round goby and age‐0 yellow perch catch was observed, indicating potential competition between the two species. This study demonstrates that variability in nearshore fish communities can be driven by factors including substrate and interspecific interactions. Given the prominent role these species play in Lake Michigan's food web and thus their importance to fishery production, a thorough understanding of these factors is warranted. 相似文献
10.
More than 22 different species concepts have been proposed. The concepts in general reflect the philosophical outlook, particular expertise, and the groups on which the authors are working. The full‐length papers in this special issue dedicated to species concepts relative to fishes are based on presentations by the authors at the 2001 annual meeting of the American Society of Ichthyologists and Herpetologists at University Park, Pennsylvania, USA and generated much discussion on the topic of what constitutes a species. 相似文献
11.
Rowshyra A. Castaeda Nicholas E. Mandrak Stuart Barrow Olaf L. F. Weyl 《水产资源保护:海洋与淡水生态系统》2020,30(7):1424-1436
- The eradication of invasive species is a management strategy implemented to eliminate adverse impacts of invaders on native species communities. After eradications, follow‐up studies are done to confirm eradication of the invasive species and the short‐term recovery of the native species, but long‐term monitoring to confirm full population recovery and stability is often not completed.
- In this study, long‐term monitoring of native fishes was carried out over 5 years after the eradication of an invasive fish from the Rondegat River, South Africa. Forty‐six sites distributed along four river sections were sampled for presence/absence using underwater cameras and snorkel surveys. Density data were collected by snorkel surveys.
- Using multi‐season occupancy models, the annual probability of colonization and local extinction of the native fishes and annual rate of change in occupancy along the river were estimated. Changes in native fish densities across time and across the control and treatment sections were analysed using Kruskal–Wallis analysis, followed by Dunn's post‐hoc test.
- Probability of colonization and local extinction differed for each native fish species and may have been affected by extrinsic factors, such as rainfall, and intrinsic density‐dependent factors, hypothesized from the density data. The occupancy rates of change revealed that the two Near Threatened fish species have reached an occupancy dynamic equilibrium but the Endangered fish has not, suggesting that other conservation efforts may be needed.
- Long‐term monitoring of native fishes after an eradication programme has confirmed the successful removal of the invader and the recovery and stability of the community. However, successful eradication was not sufficient for full recovery of all species; additional conservation management strategies are needed to secure the population stability and persistence of endangered fishes. We recommend that eradication programmes, regardless of locality, should employ long‐term monitoring to ensure full recovery of a native fish community.
12.
Takeuchi Y, Ochi H, Kohda M, Sinyinza D, Hori M. A 20‐year census of a rocky littoral fish community in Lake Tanganyika. Ecology of Freshwater Fish 2010: 19: 239–248. © 2010 John Wiley & Sons A/S Abstract – Tropical fish communities are highly diverse with large numbers of allied species coexisting. Concerns have been raised about changes in such communities caused by anthropogenic disturbances, but little is known about long‐term changes. We investigated changes in the littoral fish community of Lake Tanganyika. A 10 × 40‐m quadrat was placed on a rocky shore in the southern part of the lake, and fish censuses were conducted once a year during most years in 1988–2008. In total, 54 cichlid and 6 non‐cichlid species were recorded. Aufwuch feeders were most abundant, followed by plankton feeders, detritus feeders, piscivores, shrimp eaters, zoo‐benthos eaters, and scale eaters. Species richness and abundance were sustained over the study period, with biodiversity, as evaluated by the Shannon–Wiener index, remaining high. However, Mantel tests between the Bray–Curtis index and the difference in years between compared censuses revealed that the species composition of the community gradually changed with time. The fish community gradually underwent a change that may be due to low anthropogenic impacts on food condition. Our results promote awareness about the conservation of diversity in Lake Tanganyika. 相似文献
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14.
Peter T. Euclide Natalie M. Flores Matthew J. Wargo C. William Kilpatrick J. Ellen Marsden 《Ecology of Freshwater Fish》2018,27(3):699-709
Most of what is known about sculpin population structure comes from research in streams; however, slimy sculpins are also a common benthic species in deep lakes. In streams, sculpins are considered to be a relatively inactive species, moving only small distances, and characteristically have high levels of genetic structure. We examined population genetic structure of slimy sculpin (Cottus cognatus) across multiple barriers and over distances up to 227 km in Lake Champlain (USA, Canada) and Lake Ontario (USA, Canada) to determine whether lake populations of sculpin are also highly structured. We predicted that slimy sculpin populations in Lake Champlain would be structured by six causeways as well as by distance, Lake Ontario populations would be structured only by distance, and differences between the lakes would be large relative to within‐lake differences. We examined microsatellite variation among 200 slimy sculpins from Lake Champlain and 48 slimy sculpins from Lake Ontario to evaluate patterns of population connectivity and structure. There was no indication of population substructuring within either lake but sculpin were genetically distinct between lakes. We conclude that there is a single, panmictic population of sculpin present in Lake Champlain and another potentially panmictic population in Lake Ontario, with no indication of genetic isolation by distance. Our results contrast with data from sculpin in streams, suggesting distance and habitat fragmentation exert little influence on population connectivity of benthic fish in lakes. 相似文献
15.
The mbuna cichlids of Lake Malawi: a model for rapid speciation and adaptive radiation 总被引：6，自引：0，他引：6
Mbuna, the dominant fishes on the rocky shores of Lake Malawi, have become a major ‘model system’ for the study of rapid speciation and adaptive radiation. At least 295 putative species are known, of which more than 200 remain undescribed. There is no good evidence for monophyly in the mbuna, rather mitochondrial DNA phylogenies indicate that they are polyphlyetic with respect to benthic feeding cichlids of the genera Aulonocara, Alticorpus and some species of Lethrinops. Male mbuna hold territories for 18 months or more and breed year‐round. All species are maternal mouthbrooders, but females do not guard free‐swimming young. Mbuna are polygamous (both sexes). There is sexual dimorphism in size, colour and fin length, and many species show within‐population colour polymorphism. Mbuna genera are largely differentiated on the basis of head, jaw and tooth morphology, but congeneric species are generally distinguished by male colour. Many morphologically specialized forms have broad diets and often feed on common easily obtainable resources. While it is likely that dietary and habitat niche partitioning contributes to species coexistence, this has never clearly been demonstrated under experimental conditions. Populations on spatially separated habitat patches are often genetically differentiated, probably because most species are specialized for life on rocky shores, and lack a dispersal phase in their life histories. Males seem to disperse more than females, but are able to home several kilometres back to their territories. Some closely related ecologically equivalent allopatric populations are differentiated in male colour. Those tested have been shown to mate at least partially assortatively. Sexual selection acting on male colour seems the most plausible mechanism for initial species divergence. The same colour forms seem to have arisen several times, suggesting frequent parallel evolution. The main conservation threat to mbuna at present seems to be translocation of species within the lake as a result of the aquarium trade. However, deleterious effects on indigenous populations are not documented. In the long run, sedimentation, pollution, introduction of alien species and the development of targeted food fisheries could be more serious threats. 相似文献
16.
Assessing long‐term fish responses and short‐term solutions to flow regulation in a dryland river basin 
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下载免费PDF全文 Water resource development and non‐native species have been cited as primary drivers associated with the decline of native fishes in dryland rivers. To explore this topic, long‐term trends in the fish community composition of the Bill Williams River basin were studied over a 30‐year period (Arizona, USA). We sampled 31 sites throughout the basin that were included in fish surveys by Arizona Game and Fish in 1994–97 and the Bureau of Land Management in 1979–80. We found that non‐native species have proliferated throughout the entire basin, with greater densities in the lower elevations. Native species have persisted throughout most of the major river segments, but have experienced significant declines in frequency of occurrence and abundance in areas also containing high abundances of non‐native species. Next, we assessed the short‐term response of the fish assemblage to an experimental flood event from the system's only dam (i.e. Alamo Dam). In response to the flood, we observed a short‐term reduction in the abundance of non‐native species in sites close to the dam, but the fish assemblage returned to its preflood composition within 8 days of the event, with the exception of small‐bodied fish, which sustained lower postflood densities. Our findings demonstrate the importance of natural flow regime on the balance of native and non‐native species at the basin scale within dryland rivers and highlight minimal effects on non‐native fishes in response to short duration flood releases below dams. 相似文献
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18.
Antonella Carosi Lucia Ghetti Rosalba Padula Massimo Lorenzoni 《Fisheries Management and Ecology》2019,26(6):500-511
Global climate changes have led to a gradual warming of the planet, resulting in decreased precipitation and rising temperatures in Mediterranean inland waters. In Trasimeno Lake, the largest shallow lake in Italy, some non‐native fish species have probably benefited from these changes as they are thermophilic and characterised by wider habitat preferences. Fish data collected by gillnets and fyke nets between 1956 and 2016, and by electrofishing in 1993 and 2014, were used to analyse changes over time in the fish community in relation to environmental conditions. An explosion in goldfish Carassius auratus (L.), following its introduction in 1988, coupled with water level fluctuations and reduced transparency, contributed to the reduction in commercial fish catch in the lake, and to the decline of the endemic southern pike Esox cisalpinus Bianco & Delmastro, already threatened by reduced spawning habitat and interspecific competition with other non‐native predatory fishes. 相似文献
19.
- The mahseer (Tor spp.) fishes of South and Southeast Asia are iconic megafaunal species that are highly valued by recreational anglers. Knowledge on their populations is limited owing to the challenges associated with sampling these large‐bodied fishes (>50 kg) in remote monsoonal rivers.
- Despite its global iconic status among recreational anglers, the hump‐backed mahseer of the Cauvery River (South India) lacked a valid scientific name and was on a trajectory towards extinction until its rapidly declining population status was established by analyses of angler catch records.
- Angling records from 1998 to 2012 showed that mahseer catch rates had increased in this period. The resulting publication in Aquatic Conservation (AQC) highlighted the positive role of catch‐and‐release angling in providing information on data‐poor species. However, further analyses showed that these catches comprised not one but two distinct phenotypes.
- Before 1993, all mahseer captured were hump‐backed; since then, a blue‐fin phenotype appeared in catches and subsequently dominated them. These results triggered further studies indicating that the hump‐backed mahseer was the endemic Tor remadevii and that the blue‐fin was the invasive Tor khudree, introduced in 1976 and then stocked periodically from hatcheries.
- The initial AQC publication successfully demonstrated the high value of organized angling as a monitoring tool for data‐poor fishes and its application to assessing the temporal population patterns of large‐bodied fishes in monsoonal rivers. It was also the catalyst for initiating subsequent studies on T. remadevii that, together, enabled its recent assessment as ‘Critically Endangered’ on the International Union for Conservation of Nature (IUCN) Red List. In the absence of the AQC paper, and the subsequent studies that it triggered, it is highly probable that the species would have remained on a trajectory towards rapid extinction. Instead, the first major steps to safeguarding its future have been taken.