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Native and non-native plants provide similar refuge to invertebrate prey, but less than artificial plants.

Grutters BM, Pollux BJ, Verberk WC, Bakker ES - PLoS ONE (2015)

Bottom Line: We used aquatic communities as a model system and compared the refuge provided by plants to macroinvertebrates (Daphnia pulex, Gammarus pulex and damselfly larvae) in three short-term laboratory predation experiments.However, plant refuge provisioning to macroinvertebrate prey depended primarily on predator (mirror carp: Cyprinus carpio carpio and dragonfly larvae: Anax imperator) and prey identity, while the effects of plant structural complexity were only minor.We propose that modification of predator-prey interactions through plant invasions only occurs when invading plants radically differ in growth form, density and rigidity compared to native plants.

View Article: PubMed Central - PubMed

Affiliation: Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, the Netherlands.

ABSTRACT
Non-native species introductions are widespread and can affect ecosystem functioning by altering the structure of food webs. Invading plants often modify habitat structure, which may affect the suitability of vegetation as refuge and could thus impact predator-prey dynamics. Yet little is known about how the replacement of native by non-native vegetation affects predator-prey dynamics. We hypothesize that plant refuge provisioning depends on (1) the plant's native status, (2) plant structural complexity and morphology, (3) predator identity, and (4) prey identity, as well as that (5) structurally similar living and artificial plants provide similar refuge. We used aquatic communities as a model system and compared the refuge provided by plants to macroinvertebrates (Daphnia pulex, Gammarus pulex and damselfly larvae) in three short-term laboratory predation experiments. Plant refuge provisioning differed between plant species, but was generally similar for native (Myriophyllum spicatum, Ceratophyllum demersum, Potamogeton perfoliatus) and non-native plants (Vallisneria spiralis, Myriophyllum heterophyllum, Cabomba caroliniana). However, plant refuge provisioning to macroinvertebrate prey depended primarily on predator (mirror carp: Cyprinus carpio carpio and dragonfly larvae: Anax imperator) and prey identity, while the effects of plant structural complexity were only minor. Contrary to living plants, artificial plant analogues did improve prey survival, particularly with increasing structural complexity and shoot density. As such, plant rigidity, which was high for artificial plants and one of the living plant species evaluated in this study (Ceratophyllum demersum), may interact with structural complexity to play a key role in refuge provisioning to specific prey (Gammarus pulex). Our results demonstrate that replacement of native by structurally similar non-native vegetation is unlikely to greatly affect predator-prey dynamics. We propose that modification of predator-prey interactions through plant invasions only occurs when invading plants radically differ in growth form, density and rigidity compared to native plants.

No MeSH data available.


Related in: MedlinePlus

Refuge provisioning by native and non-native aquatic plants.Mean ± SEM survival (%) of (A) Daphnia pulex, (B) damselfly larvae and (C) Gammarus pulex under mirror carp predation (Cyprinus carpio; n = 8) and of (D) Gammarus pulex under Anax imperator predation (n = 9) in low (white bars; 300 shoots m-2) and high density (grey bars; 800 shoots m-2) plant monocultures grouped into native (left side) and non-native species (right side). Horizontal bars represent the groups that were compared. Comparisons between two groups are shown as non-significant (ns) or one to three asterisks (GLMM Wald χ2 tests: * P < 0.05; ** P < 0.01; *** P < 0.001), whereas lowercase letters indicate significance among three or more groups (GLMM simultaneous inference post hoc; P < 0.05). ‘NA’ indicates not available.
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pone.0124455.g001: Refuge provisioning by native and non-native aquatic plants.Mean ± SEM survival (%) of (A) Daphnia pulex, (B) damselfly larvae and (C) Gammarus pulex under mirror carp predation (Cyprinus carpio; n = 8) and of (D) Gammarus pulex under Anax imperator predation (n = 9) in low (white bars; 300 shoots m-2) and high density (grey bars; 800 shoots m-2) plant monocultures grouped into native (left side) and non-native species (right side). Horizontal bars represent the groups that were compared. Comparisons between two groups are shown as non-significant (ns) or one to three asterisks (GLMM Wald χ2 tests: * P < 0.05; ** P < 0.01; *** P < 0.001), whereas lowercase letters indicate significance among three or more groups (GLMM simultaneous inference post hoc; P < 0.05). ‘NA’ indicates not available.

Mentions: Plants were collected from monocultures maintained in tanks located at the Netherlands Institute of Ecology (51.9879 N, 5.6724 E). We selected three common native and three non-native Northwestern European submerged plant species with similar structural complexity (visualised in Fig 1). Common, dominant species were picked as these are expected to provide most of the ecosystem functions [43]. Effectively, dominant non-natives are expected to replace dominant natives, and its effects on refuge provision are being tested. In addition to these living plant species, four artificial plant analogues resembling Ceratophyllum, Myriophyllum, Vallisneria and Elodea were purchased for use in the third experiment (Hardeman Aquarium, Ede, Netherlands; visualised in Fig 2). After harvesting, the shoots were rinsed, cut to 25 cm and had their base wrapped in foam before being attached to a metal grid in low (~ 300 shoots m-2) or high (~ 800 shoots m-2) density using binding wire (S1 Fig). These densities were based on actual shoot densities in natural plant beds [19, 44] and prior experimental work [18]. The leaves of adjacent shoots touched each other at high density. The qualitative rigidity of all artificial plant analogues, C. demersum, and M. spicatum are described using a photograph (S2 Fig). Five fresh shoots per species were scanned (Epson Perfection 4990 Photo) and analysed for their area fractal dimension at whole-shoot and cross-sectional scale using ImageJ following [37]. The fractal dimension was calculated at these two scales as each provides different information [37]. Specifically, the shoot scale encompasses whole-plant complexity of leaf width and internode length, whereas the cross-sectional fractal dimension assesses leaf-scale complexity such as the degree of leaf dissection. After completing all the predation trials, plant wet and dry mass (60°C to constant dry weight) were determined. Shoots that had turned brown were replaced with fresh specimens during the experiment.


Native and non-native plants provide similar refuge to invertebrate prey, but less than artificial plants.

Grutters BM, Pollux BJ, Verberk WC, Bakker ES - PLoS ONE (2015)

Refuge provisioning by native and non-native aquatic plants.Mean ± SEM survival (%) of (A) Daphnia pulex, (B) damselfly larvae and (C) Gammarus pulex under mirror carp predation (Cyprinus carpio; n = 8) and of (D) Gammarus pulex under Anax imperator predation (n = 9) in low (white bars; 300 shoots m-2) and high density (grey bars; 800 shoots m-2) plant monocultures grouped into native (left side) and non-native species (right side). Horizontal bars represent the groups that were compared. Comparisons between two groups are shown as non-significant (ns) or one to three asterisks (GLMM Wald χ2 tests: * P < 0.05; ** P < 0.01; *** P < 0.001), whereas lowercase letters indicate significance among three or more groups (GLMM simultaneous inference post hoc; P < 0.05). ‘NA’ indicates not available.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4401678&req=5

pone.0124455.g001: Refuge provisioning by native and non-native aquatic plants.Mean ± SEM survival (%) of (A) Daphnia pulex, (B) damselfly larvae and (C) Gammarus pulex under mirror carp predation (Cyprinus carpio; n = 8) and of (D) Gammarus pulex under Anax imperator predation (n = 9) in low (white bars; 300 shoots m-2) and high density (grey bars; 800 shoots m-2) plant monocultures grouped into native (left side) and non-native species (right side). Horizontal bars represent the groups that were compared. Comparisons between two groups are shown as non-significant (ns) or one to three asterisks (GLMM Wald χ2 tests: * P < 0.05; ** P < 0.01; *** P < 0.001), whereas lowercase letters indicate significance among three or more groups (GLMM simultaneous inference post hoc; P < 0.05). ‘NA’ indicates not available.
Mentions: Plants were collected from monocultures maintained in tanks located at the Netherlands Institute of Ecology (51.9879 N, 5.6724 E). We selected three common native and three non-native Northwestern European submerged plant species with similar structural complexity (visualised in Fig 1). Common, dominant species were picked as these are expected to provide most of the ecosystem functions [43]. Effectively, dominant non-natives are expected to replace dominant natives, and its effects on refuge provision are being tested. In addition to these living plant species, four artificial plant analogues resembling Ceratophyllum, Myriophyllum, Vallisneria and Elodea were purchased for use in the third experiment (Hardeman Aquarium, Ede, Netherlands; visualised in Fig 2). After harvesting, the shoots were rinsed, cut to 25 cm and had their base wrapped in foam before being attached to a metal grid in low (~ 300 shoots m-2) or high (~ 800 shoots m-2) density using binding wire (S1 Fig). These densities were based on actual shoot densities in natural plant beds [19, 44] and prior experimental work [18]. The leaves of adjacent shoots touched each other at high density. The qualitative rigidity of all artificial plant analogues, C. demersum, and M. spicatum are described using a photograph (S2 Fig). Five fresh shoots per species were scanned (Epson Perfection 4990 Photo) and analysed for their area fractal dimension at whole-shoot and cross-sectional scale using ImageJ following [37]. The fractal dimension was calculated at these two scales as each provides different information [37]. Specifically, the shoot scale encompasses whole-plant complexity of leaf width and internode length, whereas the cross-sectional fractal dimension assesses leaf-scale complexity such as the degree of leaf dissection. After completing all the predation trials, plant wet and dry mass (60°C to constant dry weight) were determined. Shoots that had turned brown were replaced with fresh specimens during the experiment.

Bottom Line: We used aquatic communities as a model system and compared the refuge provided by plants to macroinvertebrates (Daphnia pulex, Gammarus pulex and damselfly larvae) in three short-term laboratory predation experiments.However, plant refuge provisioning to macroinvertebrate prey depended primarily on predator (mirror carp: Cyprinus carpio carpio and dragonfly larvae: Anax imperator) and prey identity, while the effects of plant structural complexity were only minor.We propose that modification of predator-prey interactions through plant invasions only occurs when invading plants radically differ in growth form, density and rigidity compared to native plants.

View Article: PubMed Central - PubMed

Affiliation: Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, the Netherlands.

ABSTRACT
Non-native species introductions are widespread and can affect ecosystem functioning by altering the structure of food webs. Invading plants often modify habitat structure, which may affect the suitability of vegetation as refuge and could thus impact predator-prey dynamics. Yet little is known about how the replacement of native by non-native vegetation affects predator-prey dynamics. We hypothesize that plant refuge provisioning depends on (1) the plant's native status, (2) plant structural complexity and morphology, (3) predator identity, and (4) prey identity, as well as that (5) structurally similar living and artificial plants provide similar refuge. We used aquatic communities as a model system and compared the refuge provided by plants to macroinvertebrates (Daphnia pulex, Gammarus pulex and damselfly larvae) in three short-term laboratory predation experiments. Plant refuge provisioning differed between plant species, but was generally similar for native (Myriophyllum spicatum, Ceratophyllum demersum, Potamogeton perfoliatus) and non-native plants (Vallisneria spiralis, Myriophyllum heterophyllum, Cabomba caroliniana). However, plant refuge provisioning to macroinvertebrate prey depended primarily on predator (mirror carp: Cyprinus carpio carpio and dragonfly larvae: Anax imperator) and prey identity, while the effects of plant structural complexity were only minor. Contrary to living plants, artificial plant analogues did improve prey survival, particularly with increasing structural complexity and shoot density. As such, plant rigidity, which was high for artificial plants and one of the living plant species evaluated in this study (Ceratophyllum demersum), may interact with structural complexity to play a key role in refuge provisioning to specific prey (Gammarus pulex). Our results demonstrate that replacement of native by structurally similar non-native vegetation is unlikely to greatly affect predator-prey dynamics. We propose that modification of predator-prey interactions through plant invasions only occurs when invading plants radically differ in growth form, density and rigidity compared to native plants.

No MeSH data available.


Related in: MedlinePlus