scholarly journals Existing and emerging high impact invasive species are characterized by higher functional responses than natives

2014 ◽  
Vol 10 (2) ◽  
pp. 20130946 ◽  
Author(s):  
Mhairi E. Alexander ◽  
Jaimie T. A. Dick ◽  
Olaf L. F. Weyl ◽  
Tamara B. Robinson ◽  
David M. Richardson
Keyword(s):  
Invasive Species ◽  
Micropterus Salmoides ◽  
Clarias Gariepinus ◽  
Research Priorities ◽  
Ecological Impacts ◽  
Feeding Rates ◽  
Functional Responses ◽  
Native Communities ◽  
Prey Handling ◽  
Invader Impact

Predicting ecological impacts of invasive species and identifying potentially damaging future invaders are research priorities. Since damage by invaders is characterized by their depletion of resources, comparisons of the ‘functional response’ (FR; resource uptake rate as a function of resource density) of invaders and natives might predict invader impact. We tested this by comparing FRs of the ecologically damaging ‘world's worst’ invasive fish, the largemouth bass ( Micropterus salmoides ), with a native equivalent, the Cape kurper ( Sandelia capensis ), and an emerging invader, the sharptooth catfish ( Clarias gariepinus ), with the native river goby ( Glossogobius callidus ), in South Africa, a global invasion hotspot . Using tadpoles ( Hyperolius marmoratus ) as prey, we found that the invaders consumed significantly more than natives. Attack rates at low prey densities within invader/native comparisons reflected similarities in predatory strategies; however, both invasive species displayed significantly higher Type II FRs than the native comparators. This was driven by significantly lower prey handling times by invaders, resulting in significantly higher maximum feeding rates. The higher FRs of these invaders are thus congruent with, and can predict, their impacts on native communities. Comparative FRs may be a rapid and reliable method for predicting ecological impacts of emerging and future invasive species.

scholarly journals Pushing the switch: functional responses and prey switching by invasive lionfish may mediate their ecological impact

2021 ◽  
Author(s):  
Monica McCard ◽  
Josie South ◽  
Ross N. Cuthbert ◽  
James W. E. Dickey ◽  
Nathan McCard ◽  
...  
Keyword(s):  
Functional Response ◽  
Prey Species ◽  
Effective Means ◽  
Ecological Impact ◽  
Artemia Salina ◽  
Ecological Impacts ◽  
Feeding Rates ◽  
Functional Responses ◽  
Prey Switching ◽  
Frequency Dependent

AbstractBiodiversity is declining on a global scale and the spread of invasive alien species (IAS) is a major driver, particularly through predatory impacts. Thus, effective means of assessing and predicting the consequences of IAS predation on native prey population stability remains a vital goal for conservation. Here, we applied two classic ecological concepts, consumer functional response (FR) and prey switching, to predict and understand the ecological impacts of juveniles of the lionfish (Pterois volitans), a notorious and widespread marine invader. Functional responses and prey switching propensities were quantified towards three representative prey species: Artemia salina, Palaemonetes varians, and Gammarus oceanicus. Lionfish exhibited potentially destabilising Type II FRs towards individual prey species, owing to high consumption rates at low prey densities, whilst FR magnitudes differed among prey species. Functional response attack rates (a) were highest, and handling times (h) lowest, towards A. salina, followed by P. varians and then G. oceanicus. Maximum feeding rates (1/h) and functional response ratios (FRR; a/h) also followed this impact gradient for the three prey species. Lionfish, however, displayed a potentially population stabilising prey switching propensity (i.e. frequency-dependent predation) when multiple prey species were presented simultaneously, where disproportionately less of rare prey, and more of abundant prey, were consumed. Whilst FR and FRR magnitudes indicate marked per capita lionfish predatory impacts towards prey species, a strong prey switching propensity may reduce in-field impacts by offering low density prey refuge in biodiverse communities. Our results thus corroborate field patterns documenting variable impacts of lionfish, with prey extirpations less likely in diverse communities owing to frequency-dependent predation.

scholarly journals Warming mediates intraspecific multiple predator effects from an invasive crustacean

2021 ◽  
Vol 168 (3) ◽  
Author(s):  
Ross N. Cuthbert ◽  
Ryan J. Wasserman ◽  
Tatenda Dalu ◽  
Elizabeta Briski
Keyword(s):  
Alien Species ◽  
Trophic Interactions ◽  
Invasive Alien Species ◽  
Ecological Impacts ◽  
Feeding Rates ◽  
Functional Responses ◽  
Multiple Predator Effects ◽  
Predator Interactions ◽  
The Impact ◽  
Predator Effects

AbstractInvasive alien species impacts might be mediated by environmental factors such as climatic warming. For invasive predators, multiple predator interactions could also exacerbate or dampen ecological impacts. These effects may be especially pronounced in highly diverse coastal ecosystems that are prone to profound and rapid regime shifts. We examine emergent effects of warming on the strength of intraspecific multiple predator effects from a highly successful invasive gammarid Gammarus tigrinus, using a functional response approach towards larval chironomids (feeding rates under different prey densities). Single predator maximum feeding rates were three-times higher at 24 °C compared to 18 °C overall, with potentially prey destabilising type II functional responses exhibited. However, pairs of gammarids exhibited intraspecific multiple predator effects that were in turn mediated by temperature regime, whereby synergisms were found at the lower temperature (i.e. positive non-trophic interactions) and antagonisms detected at the higher temperature (i.e. negative non-trophic interactions) under high prey densities. Accordingly, warming scenarios may worsen the impact of this invasive alien species, yet implications of temperature change are dependent on predator–predator interactions. Emergent effects between abiotic and biotic factors should be considered in ecological impact predictions across habitat types for invasive alien species.

scholarly journals Assessing the ecological impacts of invasive species based on their functional responses and abundances

2017 ◽  
Vol 19 (5) ◽  
pp. 1653-1665 ◽  
Author(s):  
Ciaran Laverty ◽  
Kyle D. Green ◽  
Jaimie T. A. Dick ◽  
Daniel Barrios-O’Neill ◽  
Paul J. Mensink ◽  
...  
Keyword(s):  
Invasive Species ◽  
Ecological Impacts ◽  
Functional Responses

scholarly journals The false widow spider Steatoda nobilis is a notable invasive species.

2019 ◽  
Author(s):  
Clive Hambler
Keyword(s):  
Invasive Species ◽  
Knowledge Exchange ◽  
Research Priorities ◽  
Ecological Impacts ◽  
Health Concern ◽  
Bite Rate ◽  
Clinical Surveillance ◽  
Street Furniture ◽  
Spider Bites ◽  
Widow Spider

Steatoda nobilis, a 'false widow' spider, has undergone massive population growth in southern Britain, at least since 1990, and is greatly under-recorded. Now often the dominant spider on and in buildings in the region, the species occurs on many items which increase a risk of bites to people - including household furniture, railings, handles, lighting and street furniture. There is a lack of awareness amongst the public, medics and arachnologists as to the likely bite rate and severity with this spider, and there is under-recording of bites. There is thus a possibility of bites being left without adequate rapid treatment and monitoring - with a low but non-trivial risk of necrosis, sepsis or anaphylactic shock. Further study of bite significance is urgently required but a typically precautionary approach should be adopted in the interim. A lag of over a century between introduction and the species rapidly becoming common in Britain indicates the risk of complacency over invasive species. Local eradication will be very difficult, so education is required on identification and response to possible bites. The species may become a widespread public health concern and a global conservation problem - particularly on islands with endemic invertebrates. Arachnologists typically have a conflict of interest which may result in understatement of risks. Research priorities include assays for venom cytotoxicity and microbial carriage, improved clinical surveillance for possible spider bites, and monitoring of the global distribution and ecological impacts. This paper aims to facilitate and stimulate inter-disciplinary knowledge exchange and gathering, to enable more appropriate and proportionate responses to bites, infestations and invasions.

scholarly journals Impacts of non-native fishes under a seasonal temperature gradient are forecasted using functional responses and abundances

NeoBiota ◽  
2019 ◽  
Vol 49 ◽  
pp. 57-75 ◽  
Author(s):  
Lubabalo Mofu ◽  
Ross N. Cuthbert ◽  
Tatenda Dalu ◽  
Darragh J. Woodford ◽  
Ryan J. Wasserman ◽  
...  
Keyword(s):  
Functional Response ◽  
Fish Species ◽  
Ecological Impacts ◽  
Seasonal Temperature ◽  
Relative Impact ◽  
Feeding Rates ◽  
Functional Responses ◽  
Mozambique Tilapia ◽  
Western Mosquitofish ◽  
Native Fishes

Developing predictive methods to forecast the impacts of existing and emerging invasive species is of critical importance to biodiversity conservation. However, invader impacts are context-dependent, making reliable and robust predictions challenging. In particular, it is unclear how temporal variabilities in relation to temperature regime shifts influence invader ecological impacts. In the present study, we quantify the functional responses of three coexisting freshwater fishes: the native freshwater River Goby Glossogobiuscallidus, and the non-native Mozambique Tilapia Oreochromismossambicus and Western Mosquitofish Gambusiaaffinis, under two temperature treatments using chironomid larvae as prey. This was used along with fish abundance data to determine temporal differences in ecological impacts of each fish species between seasons (i.e. at two corresponding temperatures). All three fish species exhibited potentially population-destabilizing Type II functional responses. Their maximum feeding rates were consistently higher in the warm temperature treatment, whereas attack rates tended to be reduced. Non-native Mozambique Tilapia had the highest maximum feeding rate under both temperature treatments (18 °C and 25 °C), followed by the non-native Western Mosquitofish and lastly the native River Goby, suggesting greater per capita impacts on native prey by non-native fishes. The predatory fish abundances differed significantly according to season, with native River Goby and non-native Mozambique Tilapia generally more abundant than non-native Western Mosquitofish. By multiplying functional response maximum feeding rates with abundances of each fish species across the seasonal gradient, the relative impact potential of non-native Mozambique Tilapia was consistently higher compared to that of native gobies. Western Mosquitofish impacts were less apparent, owing to their low abundances. We demonstrate how seasonal temperature fluctuations affect the relative impact capacities of introduced species and the utility of consumer functional response and the relative impact potential metric in impact forecasting.

scholarly journals On the RIP: using Relative Impact Potential to assess the ecological impacts of invasive alien species

NeoBiota ◽  
2020 ◽  
Vol 55 ◽  
pp. 27-60 ◽  
Author(s):  
James W. E. Dickey ◽  
Ross N. Cuthbert ◽  
Josie South ◽  
J. Robert Britton ◽  
Joe Caffrey ◽  
...  
Keyword(s):  
Invasive Species ◽  
Alien Species ◽  
Functional Response ◽  
Invasive Alien Species ◽  
Ecological Impacts ◽  
Trophic Levels ◽  
Numerical Response ◽  
Relative Impact ◽  
Functional Responses ◽  
User Friendly

Invasive alien species continue to arrive in new locations with no abatement in rate, and thus greater predictive powers surrounding their ecological impacts are required. In particular, we need improved means of quantifying the ecological impacts of new invasive species under different contexts. Here, we develop a suite of metrics based upon the novel Relative Impact Potential (RIP) metric, combining the functional response (consumer per capita effect), with proxies for the numerical response (consumer population response), providing quantification of invasive species ecological impact. These metrics are comparative in relation to the eco-evolutionary baseline of trophically analogous natives, as well as other invasive species and across multiple populations. Crucially, the metrics also reveal how impacts of invasive species change under abiotic and biotic contexts. While studies focused solely on functional responses have been successful in predictive invasion ecology, RIP retains these advantages while adding vital other predictive elements, principally consumer abundance. RIP can also be combined with propagule pressure to quantify overall invasion risk. By highlighting functional response and numerical response proxies, we outline a user-friendly method for assessing the impacts of invaders of all trophic levels and taxonomic groups. We apply the metric to impact assessment in the face of climate change by taking account of both changing predator consumption rates and prey reproduction rates. We proceed to outline the application of RIP to assess biotic resistance against incoming invasive species, the effect of evolution on invasive species impacts, application to interspecific competition, changing spatio-temporal patterns of invasion, and how RIP can inform biological control. We propose that RIP provides scientists and practitioners with a user-friendly, customisable and, crucially, powerful technique to inform invasive species policy and management.

scholarly journals Functional responses of a cosmopolitan invader demonstrate intraspecific variability in consumer-resource dynamics

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5634 ◽  
Author(s):  
Brett R. Howard ◽  
Daniel Barrios-O’Neill ◽  
Mhairi E. Alexander ◽  
Jaimie T.A. Dick ◽  
Thomas W. Therriault ◽  
...  
Keyword(s):  
South Africa ◽  
Northern Ireland ◽  
Functional Response ◽  
Ecological Impacts ◽  
Green Crab ◽  
Response Analysis ◽  
Feeding Rates ◽  
Functional Responses ◽  
Resource Dynamics ◽  
Consumer Resource

Background Variability in the ecological impacts of invasive species across their geographical ranges may decrease the accuracy of risk assessments. Comparative functional response analysis can be used to estimate invasive consumer-resource dynamics, explain impact variability, and thus potentially inform impact predictions. The European green crab (Carcinus maenas) has been introduced on multiple continents beyond its native range, although its ecological impacts appear to vary among populations and regions. Our aim was to test whether consumer-resource dynamics under standardized conditions are similarly variable across the current geographic distribution of green crab, and to identify correlated morphological features. Methods Crabs were collected from multiple populations within both native (Northern Ireland) and invasive regions (South Africa and Canada). Their functional responses to local mussels (Mytilus spp.) were tested. Attack rates and handling times were compared among green crab populations within each region, and among regions (Pacific Canada, Atlantic Canada, South Africa, and Northern Ireland). The effect of predator and prey morphology on prey consumption was investigated. Results Across regions, green crabs consumed prey according to a Type II (hyperbolic) functional response curve. Attack rates (i.e., the rate at which a predator finds and attacks prey), handling times and maximum feeding rates differed among regions. There was a trend toward higher attack rates in invasive than in native populations. Green crabs from Canada had lower handling times and thus higher maximum feeding rates than those from South Africa and Northern Ireland. Canadian and Northern Ireland crabs had significantly larger claws than South African crabs. Claw size was a more important predictor of the proportion of mussels killed than prey shell strength. Discussion The differences in functional response between regions reflect observed impacts of green crabs in the wild. This suggests that an understanding of consumer–resource dynamics (e.g., the per capita measure of predation), derived from simple, standardized experiments, might yield useful predictions of invader impacts across geographical ranges.

High predatory efficiency and abundance drive expected ecological impacts of a marine invasive fish

2020 ◽  
Vol 637 ◽  
pp. 195-208 ◽  
Author(s):  
EM DeRoy ◽  
R Scott ◽  
NE Hussey ◽  
HJ MacIsaac
Keyword(s):  
Invasive Species ◽  
Native Species ◽  
Ecological Impact ◽  
Marine Species ◽  
Ecological Impacts ◽  
Negative Effects ◽  
Marine Predator ◽  
Eastern Gulf Of Mexico ◽  
Red Grouper ◽  
Per Capita

The ecological impacts of invasive species are highly variable and mediated by many factors, including both habitat and population abundance. Lionfish Pterois volitans are an invasive marine species which have high reported detrimental effects on prey populations, but whose effects relative to native predators are currently unknown for the recently colonized eastern Gulf of Mexico. We used functional response (FR) methodology to assess the ecological impact of lionfish relative to 2 functionally similar native species (red grouper Epinephelus morio and graysby grouper Cephalopholis cruentata) foraging in a heterogeneous environment. We then combined the per capita impact of each species with their field abundance to obtain a Relative Impact Potential (RIP). RIP assesses the broader ecological impact of invasive relative to native predators, the magnitude of which predicts community-level negative effects of invasive species. Lionfish FR and overall consumption rate was intermediate to that of red grouper (higher) and graysby grouper (lower). However, lionfish had the highest capture efficiency of all species, which was invariant of habitat. Much higher field abundance of lionfish resulted in high RIPs relative to both grouper species, demonstrating that the ecological impact of lionfish in this region will be driven mainly by high abundance and high predator efficiency rather than per capita effect. Our comparative study is the first empirical assessment of lionfish per capita impact and RIP in this region and is one of few such studies to quantify the FR of a marine predator.

scholarly journals Freshwater fishes of Bontebok National Park

Koedoe ◽  
2001 ◽  
Vol 44 (2) ◽  
Author(s):  
I.A. Russell
Keyword(s):  
South African ◽  
National Park ◽  
Fish Assemblages ◽  
Micropterus Salmoides ◽  
Clarias Gariepinus ◽  
Lepomis Macrochirus ◽  
River System ◽  
Indigenous Species ◽  
Freshwater Species ◽  
Micropterus Dolomieu

Fish assemblages were sampled at six sites in the Breede River in the Bontebok National Park during 1999 and 2000. A total of 380 fish from 12 species was recorded. Indigenous fish collected included one freshwater species (Barbus andrewi), two catodromous species (Anguilla mossambica, Myxus capensis). and three estuarine species (Gilchris- tella aestuaria, Monodactylusfalciformis, Mugil cephalus). Four of the species recorded were aliens (Tinea tinea, Lepomis macrochirus, Micropterus salmoides, Micropterus dolomieu) and two species translocated from other South African rivers (Tilapia sparrmanii, Clarias gariepinus). A further two indigenous species (Sandelia capensis, Pseudobarbus biirchelli) could potentially occur within the park, though the high abundance of alien predators means that there is little chance for recolonisation from tributaries higher in the Breede River system. There is little opportunity to meaningfully conserve most indigenous freshwater fish in Bontebok National Park.

scholarly journals Aliens in the Aegean – a sea under siege (ALAS)

2020 ◽  
Vol 6 ◽  
Author(s):  
Stelios Katsanevakis ◽  
Konstantinos Tsirintanis ◽  
Maria Sini ◽  
Vasilis Gerovasileiou ◽  
Nikoletta Koukourouvli
Keyword(s):  
Remote Sensing ◽  
Invasive Species ◽  
High Resolution ◽  
Alien Species ◽  
Invasive Alien Species ◽  
Aegean Sea ◽  
Ecological Impacts ◽  
Cumulative Impacts ◽  
Cumulative Impact ◽  
Marine Habitats

ALAS aims to fill knowledge gaps on the impacts of marine alien species in the Aegean Sea, and support marine managers and policy makers in prioritizing mitigation actions. The project will focus on under-studied alien-native interactions, priority and vulnerable habitats (such as shallow forests of canopy algae and underwater caves), and apply a multitude of approaches. It will apply a standardized, quantitative method for mapping Cumulative IMpacts of invasive Alien species on marine ecosystems (CIMPAL), according to which cumulative impact scores are estimated on the basis of the distributions of invasive species and ecosystems, and both the reported magnitude of ecological impacts and the strength of such evidence. Towards that direction, ALAS will improve our knowledge base and compile the needed information to estimate CIMPAL by (1) conducting a series of field experiments and surveys to investigate the impacts of selected invasive alien species on marine habitats, (2) producing high-resolution habitat maps in the coastal zone, refining the results of previous research efforts through fieldwork, remote sensing and satellite imaging, (3) producing species distribution models for all invasive species, based on extensive underwater surveys for the collection of new data and integrating all existing information. ALAS will incorporate skills and analyses in novel ways and provide high-resolution results at a large scale; couple classic and novel tools and follow a trans-disciplinary approach, combining knowledge from the fields of invasion biology, conservation biology, biogeography, fisheries science, marine ecology, remote sensing, statistical modelling; conduct for the first time in the Aegean Sea a comprehensive, high-resolution analysis of cumulative impacts of invasive alien species; and report results in formats appropriate for decision-makers and society, thus transferring research-based knowledge to inform and influence policy decisions.

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