Dietary niche constriction when invaders meet natives: evidence from freshwater decapods

Jackson, Michelle C.; Grey, Jonathan; Miller, Katie A.; Britton, J. Robert; Donohue, Ian

doi:10.1111/1365-2656.12533

Cited by 50 publications

(51 citation statements)

References 83 publications

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“…By occupying a broad niche, theory suggests that the invader suppresses the niche size of trophically analogous native species (Jackson, Grey, et al., ; Thomson, ). Conversely, other studies have suggested that when in sympatry, the trophic niche of both the invader and native species will constrict due to dietary specialisations (Jackson, Grey, et al., ; Tran et al., 2015a, 2015b). In the experiment, there were no significant shifts in the trophic niche sizes of each species between their treatments.…”

Section: Discussionmentioning

confidence: 99%

Trophic consequences of introduced species: Comparative impacts of increased interspecific versus intraspecific competitive interactions

et al. 2017

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Invasive species can cause substantial ecological impacts on native biodiversity. While ecological theory attempts to explain the processes involved in the trophic integration of invaders into native food webs and their competitive impacts on resident species, results are equivocal. In addition, quantifying the relative strength of impacts from non‐native species (interspecific competition) versus the release of native conspecifics (intraspecific competition) is important but rarely completed.Two model non‐native fishes, the globally invasive Cyprinus carpio and Carassius auratus, and the model native fish Tinca tinca, were used in a pond experiment to test how increased intra‐ and interspecific competition influenced trophic niches and somatic growth rates. This was complemented by samples collected from three natural fish communities where the model fishes were present. The isotopic niche, calculated using stable isotope data, represented the trophic niche.The pond experiment used additive and substitutive treatments to quantify the trophic niche variation that resulted from intra‐ and interspecific competitive interactions. Although the trophic niche sizes of the model species were not significantly altered by any competitive treatment, they all resulted in patterns of interspecific niche divergence. Increased interspecific competition caused the trophic niche of T. tinca to shift to a significantly higher trophic position, whereas intraspecific competition caused its position to shift towards elevated δ13C. These patterns were independent of impacts on fish growth rates, which were only significantly altered when interspecific competition was elevated.In the natural fish communities, patterns of trophic niche partitioning between the model fishes was evident, with no niche sharing. Comparison of these results with those of the experiment revealed the most similar results between the two approaches were for the niche partitioning between sympatric T. tinca and C. carpio.These results indicate that trophic niche divergence facilitates the integration of introduced species into food webs, but there are differences in how this manifests between introductions that increase inter‐ and intraspecific competition. In entirety, these results suggest that the initial ecological response to an introduction appears to be a trophic re‐organisation of the food web that minimises the trophic interactions between competing species. A plain language summary is available for this article.

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Section: Discussionmentioning

confidence: 99%

Trophic consequences of introduced species: Comparative impacts of increased interspecific versus intraspecific competitive interactions

et al. 2017

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“…This is of concern because crayfish invasions have generally been shown to result in strong impacts on recipient ecosystems (Lodge et al, 2012) and, given the absence of native crayfish on the African continent, these impacts are likely to be even stronger, especially upon native decapods, such as freshwater crabs from the genus Potamonautes (De Moor, 2002; Jackson et al, 2016; Nunes et al, 2016). In this study, we assess the current distribution, rate of spread and population dynamics of C. quadricarinatus populations in South Africa and Swaziland.…”

Section: Introductionmentioning

confidence: 99%

Distribution and establishment of the alien Australian redclaw crayfish,Cherax quadricarinatus, in South Africa and Swaziland

Nunes

Zengeya

Hoffman

et al. 2017

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BackgroundThe Australian redclaw crayfish (Cherax quadricarinatus, von Martens), is native to Australasia, but has been widely translocated around the world due to aquaculture and aquarium trade. Mostly as a result of escape from aquaculture facilities, this species has established extralimital populations in Australia and alien populations in Europe, Asia, Central America and Africa. In South Africa, C. quadricarinatus was first sampled from the wild in 2002 in the Komati River, following its escape from an aquaculture facility in Swaziland, but data on the current status of its populations are not available.MethodsTo establish a better understanding of its distribution, rate of spread and population status, we surveyed a total of 46 sites in various river systems in South Africa and Swaziland. Surveys were performed between September 2015 and August 2016 and involved visual observations and the use of collapsible crayfish traps.ResultsCherax quadricarinatus is now present in the Komati, Lomati, Mbuluzi, Mlawula and Usutu rivers, and it was also detected in several off-channel irrigation impoundments. Where present, it was generally abundant, with populations having multiple size cohorts and containing ovigerous females. In the Komati River, it has spread more than 112 km downstream of the initial introduction point and 33 km upstream of a tributary, resulting in a mean spread rate of 8 km year−1 downstream and 4.7 km year−1 upstream. In Swaziland, estimated downstream spread rate might reach 14.6 km year−1. Individuals were generally larger and heavier closer to the introduction site, which might be linked to juvenile dispersal.DiscussionThese findings demonstrate that C. quadricarinatus is established in South Africa and Swaziland and that the species has spread, not only within the river where it was first introduced, but also between rivers. Considering the strong impacts that alien crayfish usually have on invaded ecosystems, assessments of its potential impacts on native freshwater biota and an evaluation of possible control measures are, therefore, urgent requirements.

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“…For example, the release of a new species into a species-poor community that has unexploited resources would enable the invader to utilise these resources, avoiding competitive interactions with native species and enhancing their ability to integrate into the food web (Mason, Cooke, Moles & Leishman, 2008;Juncos, Milano, Macchi & Vigliano, 2015). When the introduction is into a community where resources are fully exploited and potentially limiting, theory predicts that the interactions between the introduced and native species will result in both their trophic niches becoming constricted and divergent through dietary specialisms (Bolnick et al, 2010;Tran, Jackson, Sheath, Verreycken & Britton, 2015;Jackson, Grey, Miller, Britton, & Donohue, 2016). Conversely, these increases in competitive interactions might result in the species exploiting a wider resource base and thus resulting in larger trophic niches (Svanbäck and Bolnick, 2007).…”

Section: Introductionmentioning

confidence: 99%

Untitled

Britton¹

2019

Turk. J. Fish. Aquat. Sci.

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Predicting the ecological impacts of invasive fishes is crucial for understanding their risks in the environment. Experimental approaches that provide empirical data on invasion impacts provide both theoretical insights and data of high management utility for prioritising high-risk invaders. Here, a synthesis of some experimental approaches that predict invasion impacts of non-native fish is presented, where the focus is on impacts relating to the trophic impacts of the invader on either native trophically analogous fishes or prey populations. Experiments in tank aquaria are advantageous in providing homogenous and controlled conditions that also enable high replication. Competition-based studies can determine invasion impacts via exposure of fish to fixed food rations, although these experiments tend to produce results in intensely competitive conditions that might not occur in the wild. Comparative functional response experiments in tank aquaria have been successfully applied to determining the relative impacts of invaders compared with native species on prey populations, and have revealed high resource efficiency in globally invasive piscivorous fishes. Experiments completed in mesocosms and small ponds have the advantage of providing replicated systems in semi-natural conditions. They have been successful in revealing that rather than competing with native fishes, many invasive fishes show strong patterns of trophic niche partitioning. These patterns are also evident in these fishes when in natural invaded communities. Thus, whilst it is often suggested invasion impacts from non-native fishes result from inter-specific competition, evidence for this from experimental and field-based predictions is equivocal.

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Dietary niche constriction when invaders meet natives: evidence from freshwater decapods

Abstract: 201. Invasive species are a key driver of global environmental change, with frequently 21 strong negative consequences for native biodiversity and ecosystem processes.

Cited by 50 publications

References 83 publications

Trophic consequences of introduced species: Comparative impacts of increased interspecific versus intraspecific competitive interactions

Trophic consequences of introduced species: Comparative impacts of increased interspecific versus intraspecific competitive interactions

Distribution and establishment of the alien Australian redclaw crayfish,Cherax quadricarinatus, in South Africa and Swaziland

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