Small Benthic Fish Research Articles

Trophic trickles and cascades in a complex food web: impacts of a keystone predator on stream community structure and ecosystem processes

Chalk streams are among the most species‐rich and productive of all temperate ecosystems. Despite this, a few keystone species have the potential to exert disproportionately powerful effects on community structure and ecosystem processes. Two of these are the bullhead Cottus gobio, a small benthic fish that is an extremely abundant, voracious predator, and the freshwater shrimp Gammaruspulex, which dominates the prey assemblage and is the principal detritivore. Field experiments detected a bullhead–Gammarus–detritus trophic cascade, with detrital processing rates slowed dramatically in the presence of the predator. In addition, survey data also revealed strong negative density‐dependence between bullhead and brown trout, adding a further link in the cascade. However, although bullhead also depressed the abundance of a dominant grazer, the snail Potamopyrgus antipodarum, there was no cascading effect upon algal production, suggesting that autochthonous inputs were not controlled by top–down effects. This skewed effect of the predator upon autochthonous versus allochthonous basal resources stresses the need to consider both pathways of energy flux into the food web, whereas many previous studies have potentially overemphasized the importance of predator–herbivore–primary producer cascades. The wider community food web contained 142 species and 1383 feeding links. This complex network exhibited “small world” properties, such as high clustering (unlike many other food webs) and shortest path lengths between species were small (in common with many other food webs). In particular, each of the four members of the detrital cascade could be connected to any other species by three links or fewer. Our data revealed that powerful cascading effects can be imbedded within even very complex ecological networks.

Otter Surveys of the North West Scottish Islands

Between 1995 and 2003, otter surveys were conducted on 11 islands off the north west coast of Scotland. These located holts in a 100-metre-wide strip along the coasts of these islands. The information was then used to calculate the total number of holts for each island, and from that the adult otter population for each island was calculated using the models based on studies in Skye and Shetland. The diet of marine-foraging otters was assessed from five of these islands using spraint analysis, and was compared with the diet of otters from other coastal areas in Scotland. With the exception of the free-swimming saithe, the diet was dominated by small benthic fish, with the five key prey species being viviparous blenny, five-bearded rockling, butterfish, sea scorpion, and saithe.

Evaluation of passive integrated transponder tags for marking the bullhead (Cottus gobio), a small benthic freshwater fish: effects on survival, growth and swimming capacity

Abstract – This study examined potential adverse effects of surgically implanted passive integrated transponder (PIT) tags (12 × 2.1 mm) on bullhead (Cottus gobio L.) of three different length‐classes (I: 50–64 mm, II: 65–79 mm, III: 80–94 mm). During a 7‐week laboratory experiment, the rate of PIT tag loss, incision closure time, survival, growth and swimming capacity were tested. The PIT tag weight to fish body weight ratio varied between 1.04% and 4.85%. The mean incision closure time differed significantly among length‐classes and varied between 2.8 (I) and 4.3 (III) weeks. Nevertheless, PIT tag retention did not differ among length‐classes and was ≥90%. The survival of untagged, sham‐tagged and PIT‐tagged bullheads was ≥90% and did not differ within or among length‐classes. Finally, within each length‐class, there was no difference in growth and swimming capacity among treatments. Hence, these results suggest the applicability of PIT tags for individually tagging bullheads ≥50 mm.

Ophioblennius trinitatis (Pisces: Blenniidae) from the Oceanic Archipelagos of São Pedro e São Paulo, Fernando de Noronha and Atol das Rocas

The Blenniidae are a marine family composed of 53 genera and 345 species. They commonly occur in intertidal habitats, being dominant elements amongst the small benthic faunal fish that inhabit tropical reefs. Popularly known in Brazil as “peixes-macaco” (literally “monkey-fish”) (Carvalho-Filho, 1999; Nelson, 1994), they are usually solitary in habit, hiding cryptically in burrows, corals and sponges, thus forming part of the invisible ichthyofauna which interacts with other resident organisms. The genus

Diet of the invasive piscivorous fish Fistularia commersonii in a recently colonized area of the eastern Mediterranean

The composition of the diet of the Indo-Pacific cornetfish Fistularia commersonii from the SE Aegean Sea is described. The stomach contents of 245 specimens collected between September 2004 and March 2005 were examined. Dietary comparisons were made reflecting the relationship between diet composition, time of year, and fish size. Correlation between predator length and prey length was significant. The diet of the blue cornetfish consists of 96% by number and 99.95% by weight of fish. Size classification and habitat of prey groups (benthic, supra-benthic, and pelagic) showed that with increased body length the blue cornetfish extended its diet to larger prey and more generalist feeding. Spicara smaris, Boops boops, and Mullidae spp. were the most abundant prey by weight whereas a variety of small benthic fish (especially gobiids) and newly hatched fish constituted the largest number of prey items. Length–weight relationships for the cornetfish were investigated.

Performance of a pool-and-weir fish pass for small bottom-dwelling freshwater fish species in a regulated lowland river

Abstract Although small benthic freshwater fish species are an important biological component of fish assemblages and free instream movement is indispensable for their survival, they are often neglected in fish pass performance studies. In this study, a capture-mark-recapture approach was used to assess whether small bottom-dwelling species, including gudgeon (Gobio gobio), stone loach (Barbatula barbatula), spined loach (Cobitis taenia) and bullhead (Cottus gobio), were able to cross a pool-and-weir fish pass in a regulated lowland river. Some tagged individuals of stone loach (18%), gudgeon (7%) and spined loach (2%) managed to successfully ascend the fish pass under study, despite the fact that water velocity levels in the different overflows of the facility (between 0.55-1.22 m/s) exceeded the critical swimming speed of all three species. Although this suggests that a pool-and-weir fish pass is a able to facilitate upstream movement of some small benthic species in a regulated river, more detailed research incorporating advanced tagging and retrieving techniques is necessary.

Characterization of eight polymorphic microsatellite DNA markers for the greenside darter,Etheostoma blennioides(Percidae)

AbstractThe greenside darter,Etheostoma blennioidesis a small benthic fish found in fast‐flowing streams in eastern North America. In Canada, this species is native to three, and introduced into one, Great Lakes tributaries in southwestern Ontario. It is currently listed as a species of Special Concern. To characterize population genetic structure and diversity in the Canadian populations of greenside darter, eight polymorphic microsatellite markers were developed for the species. The polymerase chain reaction primers were tested between 32 and 60 individuals from the Sydenham River and yielded a high number of alleles (four to 42 per locus), and observed heterozygosities ranging from 0.14 to 0.82.

História natural dos amborés e peixes-macaco (Actinopterygii, Blennioidei, Gobioidei) do Parque Nacional Marinho do Arquipélago de Fernando de Noronha, sob um enfoque comportamental

Os amborês e peixes-macaco, como são popularmente conhecidos gobiídeos e bleniídeos, são elementos dominantes da fauna de pequenos peixes bentônicos e litorâneos que habitam recifes tropicais, compondo grande parte da alta diversidade das espécies de pequeno porte encontrada no Atlântico ocidental. O estudo da distribuição e história natural dos gobióides e blenióides de Fernando de Noronha foi desenvolvido através de observações de campo. Além da descrição dos hábitats preferenciais foram abordados aspectos sociais tais como, habitat preferencial, interações intra- e interespecíficas, comportamento domiciliar e territorial, e comportamento reprodutivo. A maioria das espécies em foco apresenta distribuição principalmente litorânea, são gregárias, com áreas domiciliares relativamente pequenas em torno de 2 x 2 m², pouco agressivas, tendo sido ocasionalmente registradas curtas perseguições intra- e interespecíficas. A baixa agressividade registrada, em comparação com outros peixes é provavelmente associada à adaptação à ocupação de pequenas áreas, como é o caso das poças de marés, pois um grande número de interações agressivas representaria um gasto de energia desnecessário. No geral, as espécies possuem coloração críptica, associada à evitação de predadores. Apenas nestas épocas de reprodução foi observada a intensificação da agressividade, com comportamento territorial - defesa de território incluindo mordidas e perseguições.

Feeding ecology of black anglerfish Lophius budegassa: seasonal, bathymetric and ontogenetic shifts

The diet of black anglerfish Lophius budegassa is described for the Cantabrian Sea (North Atlantic coast of Spain) from seasonal samples obtained onboard commercial vessels from January 1993 to December 1994. The stomach contents of fish caught on the continental shelf were examined, and differences in the diet in relation to age-class, season and depth were studied. The age-classes were grouped according to a cluster analysis of diet composition. As a result, three groups were obtained: the first two corresponded to juveniles between 2 and 7 years old, and the third one corresponded to adults between 8 and 15 years old. Although Micromesistius poutassou was an important prey for all ages, the youngest black anglerfish fed mainly on small benthic fish. In contrast, large prey species such as Phycis blennoides and Merluccius merluccius were eaten almost exclusively by adults. The diet composition changed during the year. The changes in the diet of black anglerfish older than 3 years were more related to seasonal differences than to between-size differences. These seasonal shifts were mainly marked by the varying importance of Trachurus trachurus and M. merluccius in their diet. Feeding intensity also showed seasonal variations, with a significant decrease in autumn. An indirect effect of depth on the feeding ecology of black anglerfish was also found, since both age and diet composition changed with depth.

First Occurrence of the Round Goby, <em>Neogobius melanostomus</em>, in the St. Lawrence River at Cornwall, Ontario

We document the first reported occurrence of the Round Goby, Neogobius melanostomus, a small benthic fish native to the Black and Caspian seas, in the St. Lawrence River near Cornwall. On 7 September 2004, we observed approximately 20 Round Gobies while SCUBA diving at a depth of 7 m, downstream of the Saunders Generating Station at Cornwall, Ontario. Round Gobies appear to have arrived recently in this reach of the river and have not previously been detected despite extensive fish surveys conducted in the area.

Scale dependent effects of predatory fish on stream benthos

In open predation experiments the effects of predators on prey densities can be influenced by predator consumption and by prey movements in to and out of experimental arenas. A published model predicts that the predator effects observed in such experiments are scale dependent over the scale range where there is a transition from movement control (of prey densities) to consumption control. The scale dependence follows from the assumption that per capita rate of emigration out of an experimental arena decreases with increasing arena size.To test this model the effects of a small benthic fish (Cottus gobio) on densities of stream invertebrates was investigated in instream channels of different length (0.5, 2 and 8 m). The effect of fish predation was scale dependent for four prey taxa. For three of these taxa predator effects increased with experimental scale, which is in agreement with model predictions. However, this proved to be a case of “making the right prediction for the wrong reason” as the basic assumption of scale dependent emigration rate was not upheld. By analyzing the behaviour of the model, parameterized with emigration and consumption rates observed in the experimental channels, it was found that observed scale effects occurred because prey emigration in response to the predator treatment was modified by the experimental scale. Further analysis of the parameterized model suggested that the densities of most prey taxa were controlled by prey movements and not by consumption by the sculpins.

Environmental factors influencing the regional distribution and local density of a small benthic fish: the stoneloach (Barbatula barbatula)

We investigated the relationships between different environmental variables and the spatial distribution patterns of the stoneloach (Barbatula barbatula) at the stream system, the stream site, and the mesohabitat (riffle/pool) scales in south-western France. Stoneloach occurred at 240 sites (out of 554 sampling sites), chiefly close to the source, in areas at low elevation and with weak slopes. Population density at a site was primarily influenced by physical conditions. Stream width was positively related to the probability of presence of stoneloach within the stream system, but negatively related to local density. These results indicate that stoneloaches can occur in a wide range of streams, but they are less abundant in wide rivers, probably because of lower habitat heterogeneity. Slope was negatively correlated to both fish presence at the regional scale and local density, suggesting that stoneloach’s swimming performance were weak under greater erosive forces. These results suggested that the distribution of populations and the density of stoneloach were governed by the suitability of physical habitat. Multi-scale studies of factors influencing a species’distribution allow to integrate patterns observed at different scales, and enhance our understanding of interactions between animals and their environment. The use of few pertinent variables in successful final models could reduce the effort and cost of data collection for water management applications.

Using stable isotope analysis with telemetry or mark-recapture data to identify fish movement and foraging

Information about animal movements has often been inferred from stable isotope analysis (SIA), but is dependent on animals assimilating site-specific isotopic signatures via diet. This potential weakness in ecological interpretation can be overcome by using other investigative tools that provide precise information about individual movement patterns. In this paper, we demonstrate the value of combining SIA with telemetry or mark-recapture data from trapping, electrofishing and remote detection of individuals to study the movement and feeding ecology of fishes in different habitats. In a fjord lake system in Newfoundland, Canada, juvenile Atlantic salmon delayed downstream migration (smolts) or actively moved into a large lake (parr) where they foraged for periods reflecting different life history strategies. In the Miramichi River (New Brunswick, Canada), SIA provided evidence of distinct foraging habitats (tributary versus large river). By tracking fish implanted with passive integrated transponder (PIT) tags, we distinguished between movements related to foraging versus seeking cool water refugia during high temperature events. Finally, site fidelity and limited mobility of slimy sculpin, a small benthic fish, was established where delta13C in muscle tissue showed a progressive enrichment downstream and where a median displacement of <10 m was estimated for sculpin tagged with PIT tags. Technological improvements have permitted non-destructive tissue sampling of wild fishes for SIA, and the tagging and remote detection of animals smaller than was previously possible. These advancements and the combination of investigative tools promise new insights into animal ecology.

Influence of riffle characteristics, surficial geology, and natural barriers on the distribution of the channel darter, Percina copelandi, in the Lake Ontario basin

The channel darter, Percina copelandi, is a small benthic fish with a wide but disjunct distribution across central North America. The development of conservation and recovery strategies for Canadian populations is limited by a lack of knowledge regarding ecology, population size and other factors that affect its distribution and abundance. We sampled five rivers in the Lake Ontario basin to test whether the distribution of P. copelandi reflected riffle habitat characteristics or landscape-scale factors such as surficial geology and natural barriers (waterfalls). At most sites yielding P. copelandi, riffles flowed into deep sand bottomed run or pool habitats. Despite a lack of association with local surficial geology or riffle habitat characteristics, both the upstream limits of P. copelandi occurrence and distribution of suitable habitats reflected the distribution of waterfalls, chutes and bedrock outcroppings. In contrast to P. copelandi, distributions of Etheostoma flabellare, P. caprodes and Rhinichthys cataractae reflected among site differences in riffle habitat.

A Comparison of Fish and Aquatic Plant Assemblages to Assess Ecological Health of Small Wisconsin Lakes

ABSTRACT Biological monitoring uses assemblage structure to assess condition of ecological systems. Taxa that effectively integrate impacts within the system of interest are useful for biological monitoring, whereas taxa that do not demonstrate predictable responses can provide ambiguous or misleading indicators. We compared the effectiveness of aquatic plant and fish assemblages for biological monitoring in 16 small lakes (< 80 ha). The lakes were limnologically similar but differed in extent of lakeshore development and type of watershed land-cover. Linear regression analysis revealed that the quality of the aquatic plant community declined with increasing lakeshore development (number of dwellings per km of shoreline), which is the primary source of impacts within this group of northern Wisconsin lakes. As lakeshore development increased, we observed a decrease in the Floristic Quality Index (FQI) of a lake, number of plant species per lake, number of highly intolerant plant species per lake, and the species richness and frequency of occurrence of floating vegetation. Conversely, fish species richness, centrarchid species richness, number of small benthic fish species, intolerant fish species richness and the proportion of the total catch of intolerant and vegetative-dwelling fish were not related to lakeshore development. These results indicate that, within the range of conditions observed, aquatic plant communities are more sensitive to lakeshore development than fish communities. Neither aquatic plant species composition nor fish assemblage variables were correlated with watershed land cover types; however all the watersheds were relatively small and undisturbed. In small lakes with few fish species, aquatic plants can be used as biological indicators for monitoring ecological conditions.

Effects of Predation Risk on Habitat Selection by Water Column Fish, Benthic Fish and Crayfish in Stream Pools

Predation risk can affect habitat selection by water column stream fish and crayfish, but little is known regarding effects of predation risk on habitat selection by benthic fish or assemblages of fish and crayfish. I used comparative studies and manipulative field experiments to determine whether, (1) habitat selection by stream fish and crayfish is affected by predation risk, and (2) benthic fish, water column fish, and crayfish differ in their habitat selection and response to predation risk. Snorkeling was used to observe fish and crayfish in, (1) unmanipulated stream pools with and without large smallmouth bass predators (Micropterus dolomieui >200 mm total length, TL) and (2) manipulated stream pools before and after addition of a single large smallmouth bass, to determine if prey size and presence of large fish predators affected habitat selection. Observations of microhabitat use were compared with microhabitat availability to determine microhabitat selection. Small fish (60–100 mm TL, except darters that were 30–100 mm TL) and crayfish (40–100 mm rostrum to telson length; TL) had significantly reduced densities in pools with large bass, whereas densities of large fish and crayfish (> 100 mm TL) did not differ significantly between pools with and without large bass. Small orangethroat darters (Etheostoma spectabile), northern crayfish (Orconectes virilis), and creek chubs (Semotilus atromaculatus) showed significantly greater densities in pools without large bass. The presence of large smallmouth bass did not significantly affect depths selected by fish and crayfish, except minnows, which were found significantly more often at medium depths when bass were present. Small minnows and large and small crayfish showed the greatest response to additions of bass to stream pools by moving away from bass locations and into shallow water. Small darters and sunfish showed an intermediate response, whereas large minnows showed no significant response to bass additions. Response to predation risk was dependent on prey size and species, with preferred prey, crayfish and small minnows, showing the greatest response. Small benthic fish, such as darters, are intermediate between small water column fish and crayfish and large water column fish in their risk of predation from large smallmouth bass.

Growth of estuarine fish is associated with the combined concentration of sediment contaminants and shows no adaptation or acclimation to past conditions.

We tested whether the growth rates of small benthic fish (Gillichthys mirabilis) in three southern California estuaries corresponded with the local concentrations of contaminants. Fish originating from each estuary were transplanted to cages in each estuary in two reciprocal transplant experiments. The growth rates of caged fish, and the size-distribution of natural populations, showed the same pattern of difference among estuaries. Twelve metals and organic contaminants occurred in bulk sediments at concentrations close to their individual ERL values, and a simple index of their combined concentration (the mean ERL quotient) was inversely correlated to the growth of caged fish. Metals in the water column occurred at lower concentrations, relative to toxicity thresholds, than those in sediments and were unrelated to fish growth. Fish used in the field caging experiments, and other fish held in the laboratory under constant conditions, showed no difference in growth according to their estuary of origin. Fish originating from different estuaries also showed no consistent differences in their tissue burden of organic contaminants. Our results thus suggested no genetic adaptation or physiological acclimation to the past contaminant regime, but revealed a possible association between fish growth rates and the combined concentration of multiple sediment contaminants.

Changes in Mediterranean rocky-reef fish assemblages exposed to sewage pollution

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 253:269-278 (2003) - doi:10.3354/meps253269 Changes in Mediterranean rocky-reef fish assemblages exposed to sewage pollution P. Guidetti*, A. Terlizzi, S. Fraschetti, F. Boero Laboratory of Zoology and Marine Biology, DiSTeBA, CoNISMa, University of Lecce, Via Provinciale Monteroni, 73100 Lecce, Italy *Email: paolo.guidetti@unile.it ABSTRACT: The fish fauna associated with shallow subtidal rocky-reefs in southern Apulia (SE Italy, Mediterranean Sea) was investigated to assess whether fish assemblage structure, and temporal trends in species richness and abundance of fishes were affected by sewage pollution. Fish assemblages were evaluated by visual census at 3 locations (3 to 4 km apart), 1 putatively impacted by a sewage outfall (discharge rate from 200 to 600 m3 h-1) and 2 controls; within each location, 3 sites (100 to 300 m apart) were surveyed 4 times over the study year. In general, dissimilarities in assemblage structures between the 2 controls were always lower than between each control and the outfall location. During winter, however, the dissimilarities between controls were very low and similar to those between each control and the outfall location, suggesting that in this period, fish assemblages from the outfall did not greatly differ from those in the controls. Planktivorous and detritivorous fishes were more abundant at the impacted location and contributed most to dissimilarities in assemblage structures between the outfall and controls. Furthermore, the outfall significantly affected total fish abundance (which was consistently about 5-fold greater at the outfall than at the controls), and temporal trends in the average density of sparids and small serranids at the scale of locations, while small benthic fishes were influenced at the scale of sites (within locations). Particulate feeders and planktivorous fishes showed different temporal trends in average densities between outfall and controls at both spatial scales examined. Species richness and density of herbivorous fishes did not show significant differences attributable to the outfall. The data thus show that nearshore sewage discharges have the potential to alter spatio-temporal patterns in littoral fish assemblages. KEY WORDS: Sewage impact · Fish assemblages · Species richness · Asymmetrical sampling design · Mediterranean Sea Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 253. Online publication date: May 15, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.

The evaluation of passive integrated transponder (PIT) tags and visible implant elastomer (VIE) marks as new marking techniques for the bullhead

To test the reliability of PIT tags and VIE marks as new marking techniques for the bullhead Cottus gobio, different tagging treatments were assayed. The relatively high recapture rates suggest the applicability of both marking techniques for this small benthic fish species.

The effect of cover on in situ predation in early benthic phase European lobster Homarus gammarus

This study examined the role of predation in restricting early benthic phase (EBP) lobsters to shelter-providing substrata. In the field, the survival of animals provided with cover in the form of cobble and gravel substrata was significantly higher than unsheltered controls. Small benthic fish, particularly gobies Pomatoschistus minutus and rockling Ciliata mustela were the primary predators subtidally while crabs Carcinus maenus appeared to be the dominant intertidal predator. Predatory attack primarily occurred within minutes of the lobsters being deployed. The study reinforces the role played by predation in restricting EBP European lobsters to shelter-providing substrata.