Presence Of Stickleback Research Articles

Warming alters the top–down effect of a common mesopredator in an aquatic food web

Global warming is altering the composition and functioning of both terrestrial and aquatic ecosystems. Most research has focussed on direct effects of warming on species and their population dynamics, while less is known about indirect effects through species interactions. Trophic cascades are especially likely to influence the effects of warming given that trophic levels differ in their response to warming because of differences in metabolism and vital rates such as growth and reproduction. We investigated if the top–down effect of a common mesopredator, the threespine stickleback, alters the impact of warming on a Baltic Sea food web. We manipulated both temperature and the presence of stickleback in mesocosms, and found the stickleback to alter the impact of warming on lower trophic levels. This was through increased consumption of herbivores that exceeded the rate at which the herbivore population could grow under higher temperature, which in turn increased algae biomass compared to a scenario without stickleback, but not compared to conditions under normal temperature. Thus, the mesopredator increased the transfer of biomass to higher trophic levels of the food web when temperature was increased. This stresses the importance of considering the impact of warming on multiple trophic levels and their interactions. Failing to consider differences in responses among trophic levels and the impact this has on their interactions can result in faulty conclusions about the impact of warming on ecosystems.

Invasive Brook Stickleback Culaea inconstans minimally alters the trophic ecology of four native fishes in Wyoming, USA

Invasive species introductions are a primary threat facing populations of native freshwater fishes. There are multiple mechanisms by which an invader can affect native species, with competition for food resources being one mechanism that can lead to declines in the distribution and abundance of native species. Invaders that are trophic generalists may cause shifts in the trophic ecology of native species and may be better suited for long-term persistence amid environmental stochasticity. Therefore, trophic studies can provide valuable information on the risk an invader poses to native species. Brook Stickleback Culaea inconstans is an invasive fish species in Wyoming whose effect on native fish assemblages is poorly understood. Our goal was to understand the potential for competitive interactions between Brook Stickleback and native fishes. We used stable isotopes of carbon (ẟ13C) and nitrogen (ẟ15N) to evaluate the feeding ecology of Brook Stickleback relative to four native fishes, and to explore whether native fish isotopic niches changed in sympatry with Brook Stickleback. We hypothesized that the isotopic niche of Brook Stickleback would be larger than that of native fishes, suggesting broader resource use. Additionally, we hypothesized that the isotopic niche of native fish populations sympatric with Brook Stickleback would contract. We did not find support for our hypotheses as the isotopic niche of Brook Stickleback was not substantially different from that of native fishes. Further, the isotopic niche of native fishes was not substantially affected by Brook Stickleback presence. As a result, we do not currently see evidence of Brook Stickleback altering the trophic ecology of native fish species. Our results provide insight to the effects of a small-bodied invasive fish species on native fishes in a previously unstudied region, and can help managers prioritize management actions to conserve native fishes.

The influence of predator community composition on photoprotective traits of copepods.

Trait expression of natural populations often jointly depends on prevailing abiotic environmental conditions and predation risk. Copepods, for example, can vary their expression of compounds that confer protection against ultraviolet radiation (UVR), such as astaxanthin and mycosporine‐like amino acids (MAAs), in relation to predation risk. Despite ample evidence that copepods accumulate less astaxanthin in the presence of predators, little is known about how the community composition of planktivorous fish can affect the overall expression of photoprotective compounds. Here, we investigate how the (co‐)occurrence of Arctic charr (Salvelinus alpinus) and threespine stickleback (Gasterosteus aculeatus) affects the photoprotective phenotype of the copepod Leptodiaptomus minutus in lake ecosystems in southern Greenland. We found that average astaxanthin and MAA contents were lowest in lakes with stickleback, but we found no evidence that these photoprotective compounds were affected by the presence of charr. Furthermore, variance in astaxanthin among individual copepods was greatest in the presence of stickleback and the astaxanthin content of copepods was negatively correlated with increasing stickleback density. Overall, we show that the presence and density of stickleback jointly affect the content of photoprotective compounds by copepods, illustrating how the community composition of predators in an ecosystem can determine the expression of prey traits that are also influenced by abiotic stressors.

Impact of the invasive three-spined stickleback (Gasterosteus aculeatus) on relative abundance and growth of native pelagic whitefish (Coregonus wartmanni) in Upper Lake Constance

Since 2013, the pelagic zone of Upper Lake Constance (ULC) has been subject to a massive invasion of the non-native three-spined stickleback (Gasterosteus aculeatus Linnaeus, 1758). Data from monthly monitoring of pelagic whitefish (Coregonus wartmanni Bloch, 1784) were used to compare weight-at-age and abundance of pelagic whitefish for years before (1997–2012) and after the invasion (2013–2015). Growth and abundance of pelagic whitefish is shown to be heavily influenced by stickleback presence. Mean autumn weight-at-age of whitefish decreased by 33.3% after the invasion took place and a significant decline in autumn CPUE in otherwise unfished cohorts of the population was also recorded. The results imply direct effects of stickleback presence on pelagic whitefish, including interspecific competition for food leading to reduced growth and survival, and predation of eggs and larvae, hampering recruitment. These observations coincide with a sharp decline in whitefish yield. In conclusion, this study shows that the invasion of stickleback has substantially altered the pelagic fish community of ULC, with severe consequences for commercial fisheries.

The Interactive Effects of Fish Predation and Conspecific Density on Survival and Growth of Tadpoles ofRana sylvaticain a Subarctic Wetland

In nature, prey are often simultaneously exposed to predators and competitors, leading to conflicting demands between survival and growth. Larval amphibians are model organisms to investigate the balancing of life history trade-offs because individuals must metamorphose before a wetland dries. Therefore, we deployed enclosures in a natural wetland to investigate the interactive effects of Wood Frog (Rana sylvatica) density (50 or 100 tadpoles) and Brook Stickleback (Culaea inconstans) presence on survival and growth of tadpoles. We hypothesized that the effects of conspecific density on tadpole survival and growth would be dependent on the presence of fish predators. Stickleback predation significantly decreased Wood Frog survival; however, a trend of higher tadpole survival with fish was detected at high conspecific densities. Wood Frog time to and mass at metamorphosis was not significantly affected by either conspecific density or stickleback presence. Our results demonstrate that Brook Sticklebacks ca...

Ecological and Evolutionary Effects of Stickleback on Community Structure

Species’ ecology and evolution can have strong effects on communities. Both may change concurrently when species colonize a new ecosystem. We know little, however, about the combined effects of ecological and evolutionary change on community structure. We simultaneously examined the effects of top-predator ecology and evolution on freshwater community parameters using recently evolved generalist and specialist ecotypes of three-spine stickleback (Gasterosteus aculeatus). We used a mesocosm experiment to directly examine the effects of ecological (fish presence and density) and evolutionary (phenotypic diversity and specialization) factors on community structure at lower trophic levels. We evaluated zooplankton biomass and composition, periphyton and phytoplankton chlorophyll-a concentration, and net primary production among treatments containing different densities and diversities of stickleback. Our results showed that both ecological and evolutionary differences in the top-predator affect different aspects of community structure and composition. Community structure, specifically the abundance of organisms at each trophic level, was affected by stickleback presence and density, whereas composition of zooplankton was influenced by stickleback diversity and specialization. Primary productivity, in terms of chlorophyll-a concentration and net primary production was affected by ecological but not evolutionary factors. Our results stress the importance of concurrently evaluating both changes in density and phenotypic diversity on the structure and composition of communities.

Short-and long term niche segregation and individual specialization of brown trout (Salmo trutta) in species poor Faroese lakes

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.

Biology and habitat use of three‐spined stickleback (Gasterosteus aculeatus) in intermittent Mediterranean streams

Abstract – We present the first data on three‐spined stickleback (Gasterosteus aculeatus) life history and habitat use in seasonal Mediterranean streams, analysing populations from NE Iberian Peninsula. Stickleback populations were strictly annual, with reproduction events involving exclusively 1+ fish. Somatic growth was concentrated in two periods, one in spring and early summer, and another in autumn and winter. During summer there was a clear stop in the somatic growth, coupled with low values of somatic condition. This growth pattern contrasts both with that of other Mediterranean stream fish species and that of stickleback in other European locations. Stickleback populations occupied mainly intermediate locations along fluvial gradients. The presence of abundant aquatic vegetation was identified as one of the main factors related with both stickleback presence and the abundance of its populations, while the latter was also negatively related with that of invasive fish and crayfish species. Stickleback tended to occur in native‐dominated fish communities, being almost absent from lower stream reaches, which bear high abundances of invasive fish species.

Aquatic invertebrate responses to fish presence and vegetation complexity in Western Boreal wetlands, with implications for Waterbird productivity

Aquatic invertebrates are essential to wetland function, serving as the key trophic link between primary producers, fish, and waterfowl in boreal wetlands. We studied how both aquatic vegetation complexity and prevalence, and fish presence, could be used to predict the distribution of invertebrate biomass in 24 wetlands of the Western Boreal Forest (WBF). The percent volume occupied by aquatic plants was significantly positively associated with overall invertebrate biomass per liter (P = 0.009). Particular invertebrate functional feeding groups were correlated with types of aquatic macrophyte architecture; herbivorous invertebrate biomass (mg/L) was greater in more complex aquatic environments, and predatory invertebrate biomass was greater in environments with simple plant architecture. Wetlands inhabited by Brook Stickleback (Culaea inconstans) had reduced invertebrate biomass of the predatory, non-predatory (excluding omnivores), and gatherer/collector functional feeding groups. Gatherer/collector, predator, shredder, and piercer invertebrate groups were negatively correlated with dissected leaved plant dominance in those wetlands without fish. These invertebrate groups comprise the bulk of invertebrate protein available to nesting hen mallards and their ducklings. We suggest that the presence of stickleback and/or dominance of dissected leaved plants in the wetlands of the WBF results in decreased food supply for hatchling waterfowl.

Escape behaviour and ultimate causes of specific induced defences in an anuran tadpole

Induced defences, such as the predator avoidance morphologies in amphibians, result from spatial or temporal variability in predation risk. One important component of this variability should be the difference in hunting strategies between predators. However, little is known about how specific and effective induced defences are to different types of predators. We analysed the impact of both pursuing (fish, Gasterosteus aculeatus) and sit-and-wait (dragonfly, Aeshna cyanea) predators on tadpole (Rana dalmatina) morphology and performance (viz locomotive performance and growth rate). We also investigated the potential benefits of the predator-induced phenotype in the presence of fish predators. Both predators induced deeper tail fins in tadpoles exposed to threat of predation, and stickleback presence also induced longer tails and deeper tail muscles. Morphological and behavioural differences resulted in better escape ability of stickleback-induced tadpoles, leading to improved survival in the face of stickleback predation. These results clearly indicate that specific morphological responses to different types of predators have evolved in R. dalmatina. The specific morphologies suggest low correlations between the traits involved in the defence. Independence of traits allows prey species to fine-tune their response according to current predation risk, so that the benefit of the defence can be maximal.

Predator-induced plasticity in early life history and morphology in two anuran amphibians.

Predation pressure during early life stages is often high, but few studies have examined antipredator responses at these stages. We studied the effects of an egg predator (leech, Haemopis sanguisuga) and two tadpole predators (dragonfly larvae, Aeshna spp.; and threespine stickleback, Gasterosteus aculeatus) on the timing of hatching and morphology of hatchlings and young tadpoles in two anuran amphibians [Rana arvalis (RA) and R. temporaria (RT)] in a factorial laboratory experiment. We also compared the responses of two geographically separated RA populations on the Baltic island of Gotland and in Uppland on the Swedish mainland. We found inconsistent evidence for the predictions that the presence of an egg predator induces earlier hatching, and the presence of a larval predator delays hatching. RT hatched later in the presence of stickleback than in the control treatment, but RA hatched earlier, less developed and at smaller size in the leech, dragonfly, and stickleback treatments. There was no indication of predator-induced morphology in hatchlings of either of the species. However, young RA tadpoles had shorter tails and deeper bodies in the stickleback treatment and RT had shorter tails in the leech, dragonfly and stickleback treatments. Irrespective of treatment, RA from Gotland hatched with relatively longer bodies than Uppland individuals and had relatively deeper and short tails as young tadpoles. Our results highlight the diversity of induced responses to predators in anuran amphibians: predator presence affects the timing of hatching and morphology of young tadpoles, but these responses vary depending on the species and predator considered.

Threespine stickleback aggregations create a potential predation refuge for sockeye salmon fry

Coho salmon (Oncorhynchus kisutch) frequently consume sockeye salmon (Oncorhynchus nerka) fry in Chignik Lake, Alaska, but have never been observed to consume threespine sticklebacks (Gasterosteus aculeatus), which are often closely associated with sockeye fry. Because coho salmon are visual predators and appear to avoid sticklebacks, a series of experiments was conducted in net pens to determine whether juvenile sockeye associated with threespine sticklebacks experienced less prédation than sockeye without sticklebacks and whether prey size affected prédation rates. Significantly fewer sockeye fry by coho were consumed in the pen containing 60 sticklebacks [Formula: see text] than in the 30-stickleback (4.7 fry/day) and 0-stickleback (4.4 fry/day) pens. An identical experiment with large, yearling sockeye (rather than sticklebacks) did not reveal a significant effect (p = 0.28), although there was a tendency for fewer large fry to be consumed when yearlings were abundant. A third experiment demonstrated predation rates on fry that were 45% lower in the presence of sticklebacks (1.2 fry/day) than in the presence of yearling sockeye (2.2 fry/day). Large sockeye fry (37–44 mm) consumed by coho declined steadily from about 36 to 29 to 22% of the total number of fry eaten as the number of sticklebacks or yearling sockeye increased from 0 to 30 to 60, respectively. These data suggest that the presence of threespine sticklebacks may reduce predation by coho on juvenile sockeye, especially those sockeye similar in size to sticklebacks.