Niche flexibility and trout–galaxiid co-occurrence in a hydrologically diverse riverine landscape

McHugh, Peter A.; McIntosh, Angus R.; Howard, Simon; Budy, Phaedra

doi:10.1007/s10530-012-0237-6

Cited by 18 publications

(17 citation statements)

References 46 publications

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“…Additionally, ubiquitous mayflies Deleatidium spp. were collected with a kick net at each sampling reach at the same time as were the fish samples, to be used as a baseline primary consumer to standardize the nitrogen isotope values for the fish across streams (McHugh et al 2012;Fraley et al 2018).…”

Section: Methodsmentioning

confidence: 99%

Influence of Maternally‐Transferred Nitrogen and Carbon on Stable Isotope Ratios in Juvenile Chinook Salmon

Fraley

McHugh

McIntosh

2019

N American J Fish Manag

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In freshwater fishes, the nitrogen and carbon stable isotopes ratios in tissues commonly reflect the environment in which a fish is feeding, assimilated through its diet. For many species, small‐bodied or younger individuals generally feed lower in the food chain, while large‐bodied mature individuals feed at higher trophic levels. This is reflected in the stable isotope (SI) ratios within fish tissue, with large‐bodied fish typically exhibiting more enriched isotope signatures. However, an inverse relationship has been seen in recently‐hatched, premigratory juvenile fishes of anadromous maternal stock. This has been documented previously in some salmonids, and it is due to the maternal contribution of marine‐derived nitrogen to juvenile fish, which fades with isotopic turnover as they grow and assimilate energy from freshwater food webs. However, this phenomenon has not been previously documented for wild Pacific salmonids, as we present here. We found that the isotope ratios of premigratory juvenile Chinook Salmon Oncorhynchus tshawytscha were elevated at posthatch, declined with increased body size, and converged with those of sympatric freshwater resident Brown Trout at 3.39 g body mass or 79 mm TL (at approximately 48–84 d posthatch). Given our findings, researchers should account for the lingering maternal isotopic enrichment of premigratory juvenile salmon to avoid introducing bias into SI‐based freshwater food web studies. Additionally, the maternal life history (sea‐run or resident) for the progeny of partially anadromous Pacific salmonids can likely be classified by examining SI information, which is supported by our results and by previous research on other anadromous salmonids. Therefore, SI analysis could be a useful tool for characterizing the relative contribution of anadromous females in partially migratory populations of other Pacific salmonids (e.g., steelhead Oncorhynchus mykiss) to help with the management and conservation of these sensitive fish species.

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Section: Methodsmentioning

confidence: 99%

Influence of Maternally‐Transferred Nitrogen and Carbon on Stable Isotope Ratios in Juvenile Chinook Salmon

Fraley

McHugh

McIntosh

2019

N American J Fish Manag

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“…and frozen prior to transport back to the laboratory to use as a baseline to compare with fish for SI FCL analysis (McHugh et al, 2012).…”

Section: Stable Isotope Preparation and Analysismentioning

confidence: 99%

“…TP is typically calculated for individual organisms using nitrogen isotope ratios, and organisms with higher TP values are nearer to the apex of an ecosystem's trophic pyramid (McHugh, McIntosh, Howard, & Budy, 2012;Post, 2002). Along with nitrogen isotopes, isotopes of carbon are also typically measured because the range in carbon isotope ratios (carbon range) among co-occurring organisms describes the dietary breadth of fishes in an assemblage (McHugh et al, 2012). The calculation of TP values for all species allows inferences to be made about the structure of an entire food web, and these SI-derived TP values are comparable among similar systems.…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, SI analysis is a useful technique, with broad applications for ecology (Fry, 2006;Richet, Bottinga, & Janoy, 1977), and is commonly used to assess TP (Vander Zanden, Cabana, & Rasmussen, 1997) and energy transfer through food chains (Post, 2002). TP is typically calculated for individual organisms using nitrogen isotope ratios, and organisms with higher TP values are nearer to the apex of an ecosystem's trophic pyramid (McHugh, McIntosh, Howard, & Budy, 2012;Post, 2002). The TP of top predators is determined by comparing the nitrogen isotope ratio of the predator relative to the value for a standard primary consumer within the same habitat (known as FCL).…”

Section: Introductionmentioning

confidence: 99%

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Responsiveness of fish mass–abundance relationships and trophic metrics to flood disturbance, stream size, land cover and predator taxa presence in headwater streams

Fraley

Warburton

Jellyman

et al. 2018

Ecology of Freshwater Fish

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Characterisation of food webs, by summarising energy transfer and trophic relationships, allows more functional measurement of ecosystems and may reveal threats (e.g., land-cover change) in sensitive environments that are not obvious from conventional biomonitoring. However, typical methods used to achieve this are timeconsuming and expensive. Therefore, we tested the usefulness of fish-focused food-web proxies as functional measures, specifically mass-abundance relationships of fish assemblages and stable isotope (SI)-derived metrics in headwater stream reaches. These metrics have been trialled before for similar use in other settings, but have yielded varying results, and have not been employed in tandem in temperate freshwaters. Sampling reaches (N = 46) were spread across a variety of streams, and the effects of habitat predictors at multiple scales on metrics were assessed using model selection. We found that habitat size positively correlated with food-chain lengths in streams, possibly because of increased abundance of fish at multiple trophic levels in habitats with more space. Additionally, flood disturbance was negatively associated with fish mass-abundance and carbon range, likely due to the harshness of flood-prone streams. Riparian land-cover variables were correlated with multiple metrics, indicating the importance of terrestrial-aquatic linkages.Additionally, variations in all metrics were influenced by the presence of native, predatory longfin eels. Overall, we conclude that mass-abundance relationships and SIderived metrics are sensitive to drivers of trophic organisation and likely reflect processes occurring at multiple spatial scales in freshwaters. Thus, these metrics could be an insightful monitoring tool for managers because they reflect functional measures of aquatic ecosystems. K E Y W O R D S fish assemblages, habitat relationships, trophic relationships S U PP O RTI N G I N FO R M ATI O N Additional Supporting Information may be found online in the supporting information tab for this article. How to cite this article: Fraley KM, Warburton HJ, Jellyman PG, Kelly D, McIntosh AR. Responsiveness of fish massabundance relationships and trophic metrics to flood disturbance, stream size, land cover and predator taxa presence in headwater streams. Ecol Freshw Fish.

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“…Results for fish were not always consistent with those for primary consumers, however this is not surprising given the variability in isotopic values of potential prey items. Galaxiid fishes are opportunistic feeder, with diet dependent on prey availability (McHugh et al 2012), but which include driftfeeding at the water surface on terrestrial insects, whereas pygmy perch are mainly benthic feeders. Stomach contents in the present study indicated that although G. occidentalis and N. vittata diets varied, they were distinct because Galaxias' diet included nekton and terrestrial insects whereas Nannoperca consumed benthic detritus.…”

Section: Native Fishmentioning

confidence: 99%

Potential of submerged macrophytes to support food webs in lowland agricultural streams

Paice

Chambers

Robson

2017

Mar. Freshwater Res.

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Submerged plants are often abundant in lowland streams in agricultural landscapes, but little is known of their role in stream ecosystems compared to riparian vegetation.We investigated the relative importance of submerged macrophytes as a basal resource of food webs in stream reaches with good and poor riparian vegetation condition, using mixing model analysis with stable carbon and nitrogen isotopes.Epilithic periphyton and terrestrial detritus were important basal resources in good condition reaches, although where macrophytes were present, they did contribute to food webs. Higher assimilation of either the macrophyte Cycnogeton huegelii or conspicuous epiphytes on C. huegelii leaves was associated with poor riparian condition. Where Potamogeton ochreatus and Ottelia ovalifolia occurred in poor condition reaches, these macrophytes contributed moderately to the food web, but were probably of greater importance as substrates for epiphytic algae. Mixing models indicated invertebrates commonly had generalist feeding strategies, feeding on the most available resource at each reach. Thus where riparian vegetation is limited, submerged macrophytes may support opportunistic consumers both directly and as a substrate for epiphytes, thereby partially compensating for the loss of allochthonous resources in lowland agricultural streams.

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Niche flexibility and trout–galaxiid co-occurrence in a hydrologically diverse riverine landscape

Cited by 18 publications

References 46 publications

Influence of Maternally‐Transferred Nitrogen and Carbon on Stable Isotope Ratios in Juvenile Chinook Salmon

Influence of Maternally‐Transferred Nitrogen and Carbon on Stable Isotope Ratios in Juvenile Chinook Salmon

Responsiveness of fish mass–abundance relationships and trophic metrics to flood disturbance, stream size, land cover and predator taxa presence in headwater streams

Potential of submerged macrophytes to support food webs in lowland agricultural streams

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