Ian C. Duggan

Ian C. Duggan
The University of Waikato · Te Aka Mātuatua - School of Science

PhD

About

95
Publications
29,974
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,990
Citations
Introduction
My main interests are invasion biology and zooplankton ecology. In particular, I am interested in the exploration of biological invasion vectors responsible for transportation of species at global or finer scales. Such investigations are useful for prediction and prevention of invasions of nonindigenous species. If you would like pdfs of my publications, please email me.
Additional affiliations
January 2004 - present
The University of Waikato
Position
  • Invasion vectors and patterns in invasions in aquatic ecosystems.
January 2002 - January 2004
University of Windsor
Position
  • Shipping and Aquarium Trade
January 2001 - present
The University of Waikato

Publications

Publications (95)
Article
Full-text available
It is now widely accepted that the construction of new lakes, ponds and reservoirs facilitates the invasion of non-indigenous aquatic species, due largely to low biotic resistance from native communities. The role played by constructed waters appears to be a particularly frequent feature of zooplankton invasions. Charles Elton, in his classic 1927...
Article
Full-text available
While numerous examples exist of freshwater species from aquaculture facilities establishing non-indigenous populations following intentional release, and unintentional escape, clear links between invasions of non-target ‘hitchhiker’ species and this vector are to date are far less convincing. We examined zooplankton from nine New Zealand fish farm...
Article
Full-text available
Propagule pressure is frequently cited as an important determinant of invasion success for terrestrial taxa, but its importance for aquatic species is unclear. Using data on aquarium fishes in stores and historical records of fish introduced and established in Canadian and United States waters, we show clear relationships exist between frequency of...
Article
Understanding the mechanisms that facilitate establishment of non-indigenous species is imperative for devising techniques to reduce invasion rates. Passively dispersing non-indigenous organisms, including zooplankton, seemingly invade constructed waters (e.g., ornamental ponds, dams and reservoirs) at faster rates than natural lakes. A common attr...
Article
Globally-threatened freshwater mussels belonging to the order Unionida (Bivalvia) may be adversely affected by dense beds of submerged macrophytes that modify habitat at the sediment-water interface. Such effects can be particularly pronounced in modified lentic ecosystems such as reservoirs which are subject to hydrological regimes (e.g., hydropea...
Article
Larval behaviour for many of New Zealand’s diadromous freshwater fish is inadequately described. Diadromy for many amphidromous species is not obligatory however, and where conditions are suitable, freshwater larval rearing may be facilitated. Where this occurs in lakes, opportunities to document the composition and conditions supporting larval rea...
Article
Full-text available
Data collected on zooplankton community composition over longer time periods (> 10 years) are rare. We examined among-lake spatial and temporal trends of zooplankton communities from a monitoring programme undertaken in the Waikato region, New Zealand. A total of 39 lakes were sampled over a period of 12 years, between 2007 and 2019, with varying d...
Article
Full-text available
Aim We investigated evolutionary relationships and biogeographical patterns within the genus Boeckella to evaluate (1) whether its current widespread distribution in the Southern Hemisphere is due to recent long-distance dispersal or long-term diversification; and (2) the age and origin of sub-Antarctic and Antarctic Boeckella species, with particu...
Article
Kākahi (Echyridella spp.) are freshwater cultural keystone species in New Zealand; they represent a valuable mahinga kai (species used as a food) resource and have high cultural significance to Māori, particularly to the Te Arawa and Ngāti Tūwharetoa iwi (tribal groups). Population densities of kākahi are thought to have declined in many locations...
Article
Few studies have examined zooplankton assemblages associated with grey willow (Salix cinerea) invasions in wetlands. Our aim was to quantitatively examine zooplankton composition among S. cinerea stands within the South Taupō Wetland, New Zealand, to determine whether these assemblages are affected by willow growth and willow control treatment usin...
Article
Dense macrophyte beds are known to produce extreme diurnal oxygen and temperature conditions in shallow lakes. However their influences in managed hydropeaking reservoirs has received limited attention. We measured dissolved oxygen, pH and water temperature in the Lake Karāpiro hydroreservoir, northern New Zealand, across a gradient of proportional...
Article
Constructed waters (e.g. dams and retired quarries) are commonly found to have a different zooplankton composition than are natural waters, and to be more readily invaded by non-indigenous species. Constructed ponds are common on farmland, but zooplankton research in these areas is scarce. Consequently, our aims were to (1) compare zooplankton comm...
Article
New Zealand's native freshwater mussels (kākahi, kāeo) are considered to be in decline, yet the mechanisms driving this are unclear. The widespread establishment of highly efficient filter-feeding, non-native Daphnia in New Zealand lakes may have led to competition for algae with kākahi. We conducted a controlled laboratory experiment to determine...
Article
Few studies have examined the effects of freshwater mussels on zooplankton in their native regions. We undertook an outdoor mesocosm-scale experiment to examine the effects of Echyridella menziesii, an endemic New Zealand mussel, on zooplankton composition. Experiments were undertaken in 125-L cylindrical drums that were randomly separated into the...
Article
Full-text available
The trematode parasite Transversotrema patialense (Soparkar, 1924) (Digenea: Transversotrematidae) is reported from New Zealand for the first time. The parasite was first observed serendipitously within water surrounding the non-indigenous thiarid snail Melanoides tuberculata, a known intermediate host, bought from an online Auckland aquarium trade...
Article
• Understanding the multiple agents of decline is important for the conservation of globally threatened Unionida (Class Bivalvia), but threats from non‐native species have received limited attention. To address this gap, a global meta‐analysis was conducted aimed at identifying known interactions and mechanisms of impact and informing potential eff...
Article
Interactions between two recent invaders to New Zealand, the cladocerans Daphnia galeata and D. pulex, and native filter-feeding freshwater mussels, are unknown. We examined predation rates of the common native mussel Echyridella menziesii (kākahi, kāeo) on non-native Daphnia (comparatively large zooplankton in New Zealand), relative to two common...
Article
Non-indigenous zooplankton species pose a biosecurity threat to New Zealand’s freshwater native taxa. Nine species are known to have established in New Zealand lakes to date. The spread of some zooplankton taxa is linked to the translocation of farmed fish, principally grass carp (Ctenopharyngodon idella), and recreational vessel movements. The aim...
Article
We analysed 344 juvenile Galaxias maculatus (length 35-59 mm) collected from two sites in the lower Waikato River, North Island, New Zealand, to determine diet during the period of upstream migration (August-November). In total, 53% of guts contained invertebrate food items comprising 16 taxa, with Cladocera numerically most abundant overall (32% o...
Article
Full-text available
Invertebrate species carried incidentally (i.e., ‘hitchhikers’) in the aquarium trade have gained increasing attention in recent years, but factors affecting the movement of species from stores to homes are poorly understood. We aimed to determine how macrophytes bought from stores act as vectors for transport of non-indigenous invertebrate species...
Article
Full-text available
Non-native freshwater zooplankton species have been recorded from aquaculture ponds in New Zealand and Italy, while zooplankton invasions elsewhere have implicated the aquaculture industry as the vector for introduction. However, the prevalence of non-native species in international aquaculture facilities is unclear. We undertook a literature revie...
Article
Full-text available
We summarise current understanding of consumer recycling in lake nutrient cycles and expand on it by integrating emerging knowledge from food web ecology. The role of consumer nutrient recycling (CNR) is initially framed in the wider context of lake nutrient cycling, which includes hydrodynamic and biogeochemical processes, and their responses to g...
Article
Zooplankton are an essential component of healthy functioning lake and wetland ecosystems. Despite this, zooplankton communities within constructed treatment wetlands (CTWs) in agricultural landscapes remain unstudied. Taxa richness, total abundances and community composition were evaluated for zooplankton assemblages from three habitat types (lake...
Article
In the present study we tested the effects of translocations from aquaculture facilities of grass carp, one of the most commonly used species in aquaculture globally, to constructed ponds in the Auckland region, New Zealand. Primarily, we were interested in whether zooplankton assemblages in recipient ponds are affected by the concomitant introduct...
Article
Lakes are among the most seasonally forced ecosystems on Earth. Seasonal variation in temperature and light produce cyclic patterns in water column mixing, nutrient supply and phytoplankton biomass. Diet responses of consumers to these patterns have rarely been quantified. Moreover, pelagic-littoral coupling of dietary resources by mobile consumers...
Article
Full-text available
Until recently, only one native and three apparently introduced Daphnia species were known from New Zealand. We demonstrate that (1) Daphnia in subalpine habitats in southern New Zealand differ morphologically and genetically from the native taxon previously labelled Daphnia carinata to merit species nova status and (2) the name of the latter shoul...
Article
High Rate Algal Ponds (HRAPs) with addition of CO2 are open pond wastewater treatment systems that recover nutrients as microalgal biomass. Such ponds are vulnerable to contamination by opportunistic zooplankton species able to survive the wastewater HRAP environment. The high food availability and a near neutral pH can promote the rapid developmen...
Article
Full-text available
The freshwater calanoid copepod Skistodiaptomus pallidus (Herrick, 1879), native to the Mississippi basin of North America, has recently established non-indigenous populations in New Zealand, Germany and Mexico. We used the mitochondrial cytochrome c oxidase subunit I (COI) gene to more precisely identify the origins of S. pallidus populations with...
Article
Cladocerans and rotifers rapidly consume beneficial microalgae and reduce the performance of High Rate Algal Ponds (HRAPs) for wastewater treatment and algal production. Potential zooplankton control treatments for HRAPs have been proposed and tested at a laboratory scale including CO2 asphyxiation, biological control using competitor species, filt...
Article
Zooplankton taxa including cladocerans and rotifers are one of the greatest challenges for effective management of High Rate Algal Ponds (HRAPs) for wastewater treatment as they can establish and rapidly consume beneficial microalgae. Harmful zooplankton need to be controlled using cost effective treatments, and here we tested under controlled labo...
Article
We tested whether variability in zooplankton assemblages was consistent with the categories of estuarine environments proposed by the ‘Estuary Environment Classification’ system (EEC) (Hume et al., 2007) across a variety of North Island, New Zealand, estuaries. The EEC classifies estuaries in to eight categories (A to F) based primarily on a combin...
Article
We investigated the potential for zooplankton to emerge following inundation of dry soils on the lower Waikato River floodplain, North Island, New Zealand. Soil cores were collected from native forest remnants, scrub (predominantly Salix spp.) and pasture, and from sites inside or outside of stopbanks, to examine the effects of vegetation type and...
Article
We sampled natural and reconstructed side-arms during different stages of hydrological connectivity with a large floodplain river in northern New Zealand, to determine whether re-establishment of connectivity would be an effective strategy for restoring plankton communities in former side-arms. Connectivity between side-arms and the river was moder...
Article
High Rate Algal Ponds (HRAPs) with artificial addition of CO2 provide improved tertiary-level wastewater treatment over conventional HRAPs. One of the greatest challenges for performance and management of HRAPs with CO2 addition is the establishment of zooplankton grazers that can consume much of the algal biomass within a few days. High food avail...
Article
[Beginning of Introduction] Garden gnomes are a dominant, and iconic, component of the suburban garden statuary in many parts of the world, including England, North America, Australia and New Zealand. These ornaments have traditionally been depicted as bearded ‘dwarf-like’ human figures, male, with a red pointed hat, although this representation ha...
Article
While depictions of mariners fighting fearsome sea monsters or battling terrifying storms entertain us to this day, it is perhaps ironic that one of the main threats to commerce over the last millennium or more has come from a series of very small organisms whose history has been submerged in historical accounts. Despite their marked long-term and...
Article
Full-text available
Taxonomic and ecological studies of freshwater harpacticoid copepods are limited globally by the ability to easily and accurately identify specimens. Here, we test the use of the mitochondrial cytochrome c oxidase subunit I (COI) gene locus as a tool for assessing the diversity of freshwater Harpacticoida. We obtained sequences from New Zealand har...
Article
Brown trout (Salmo trutta) are known to have effects on multiple trophic levels in New Zealand streams, but their impacts on lower trophic levels are less well understood within lentic systems. We examined the effects of brown trout removal using rotenone on zooplankton and phytoplankton community composition in the Upper Karori Reservoir, New Zeal...
Article
Full-text available
The North American calanoid copepod Skistodiaptomus pallidus is an emerging invader globally, with non-indigenous populations recorded from constructed waters in New Zealand, Germany and Mexico since 2000. We examined the effects of S. pallidus establishment on the zooplankton community of a natural lake, Lake Kereta, where it was first recorded in...
Article
The ecological responses of large rivers to human pressure can be assessed at multiple scales using a variety of indicators, but little is known about how the responses of ecological indicators vary over small spatial scales. We sampled phytoplankton, zooplankton and macroinvertebrates and measured river metabolism and cotton strip breakdown rates...
Article
1. Large river–floodplain systems are characterised by seasonal flow variability. High flows lead to hydrological connection between the main channel and inundated off-channel lakes, wetlands and floodplains, which provide essential habitats for riverine biota. We tested the following hypotheses: (i) that crustacean zooplankton are more abundant in...
Article
Encroachment of urban areas into forest and farmland is typically considered to have detrimental effects on terrestrial and aquatic ecosystems. Most restoration strategies for lakes affected by urban development represent expensive short-term fixes requiring on-going management, with long-term restoration requiring external nutrient inputs (typical...
Article
Full-text available
We used a DNA barcoding approach to identify specimens of the Daphnia pulex complex occurring in New Zealand lakes, documenting the establishment of non-indigenous North American Daphnia ‘pulex’. Morphological delineation of species in this complex is problematic due to a lack of good morphological traits to distinguish the species, as there is a r...
Article
AimConstructed water bodies (e.g. water supply and hydroelectricity dams, ornamental ponds) are invaded at faster rates than natural waters, but the mechanisms that lead to this pattern are uncertain. We aimed to determine whether constructed lakes have lower zooplankton species richness or differ in species composition relative to natural waters,...
Article
Full-text available
The freshwater cnidarian Craspedacusta sowerbii, native to the Yangtze valley, has invaded lakes and ponds throughout the world. Most distribution records have to date been based on observations of the medusa (jellyfish) stage, including numerous recent publications. We aimed to determine whether polyps are widespread in lakes, and geographical are...
Article
To quantify the effects of a future climate on three morphologically different lakes that varied in trophic status from oligo-mesotrophic to highly eutrophic, we applied the one-dimensional lake ecosystem model DYRESM-CAEDYM to oligo-mesotrophic Lake Okareka, eutrophic Lake Rotoehu, both in the temperate Bay of Plenty region, and highly eutrophic L...
Article
We tested the hypothesis that structural complexity is an important factor influencing the abundance and taxon richness of microfauna (e.g., rotifers, copepods, cladocerans) in littoral habitats. Research on littoral microfauna has to date focused mainly on field observations, which commonly show microfauna have preference for some macrophytes over...
Chapter
Full-text available
The Gnathifera includes the free-living lesser jaw worms (Gnathostomulida) and parasitic thorny-headed worms (Acanthocephala) as well as the unwormlike rotifers. These groups used to be treated as separate phyla, and still are in many textbooks. In lacking a body cavity and through-gut with a permanent anus, gnathostomulids were included among flat...
Article
A number of zooplankton invasions have been linked with the movement of plants to botanical and other public gardens. Although most of these records are historical, several recent examples indicate that aquatic fauna may still be transported by plant movements among gardens, or that there are unrecognised long-standing established populations in ga...
Article
Full-text available
Although in situ sediment capping is frequently used to reduce internal loading of contaminants and nutrients, post-application assessment rarely includes the potential undesirable short-term effects on plankton species composition. We hypothesised that a modified zeolite (Z2G1) application as a sediment capping agent in Lake Okaro, New Zealand, co...
Article
Full-text available
We report the discovery of a single specimen of a live apple snail Pomacea diffusa Blume 1957 (Ampullariidae: Prosobranchia), from the Waikato River, Hamilton city, central North Island, New Zealand. This species, along with the congeneric P. insularum, is imported for the aquarium trade, and its occurrence in the river likely stemmed from an aquar...
Chapter
Full-text available
Article
1. Although Sinodiaptomus valkanovi [sensu Ueda & Ohtsuka (Hydrobiologia, 379, 1998, 159)] is one of the most common freshwater calanoid copepods in Japan, it was originally described from specimens collected in Sofia, Bulgaria, as a subspecies of S. sarsi. This original description raises two issues requiring further investigation. One is whether...
Article
The aquarium trade has a long history of transporting and introducing fish, plants and snails into regions where they are not native. However, other than snails, research on species carried “incidentally” rather than deliberately by this industry is lacking. I sampled invertebrates in the plankton, and from water among bottom stones, of 55 aquaria...
Article
Full-text available
Barrier bars separating lagoons from oceans are frequently breached as a management tool to prevent flooding of terrestrial ecosystems. The effects of such human-mediated openings on zooplankton have been investigated only in one tropical system. We investigated the temperate Waituna Lagoon, New Zealand, over a 2-year period when the barrier bar wa...
Chapter
Full-text available
Article
Full-text available
We examined the temporal and vertical dynamics of zooplankton in Weavers Lake, New Zealand, between October 2004 and October 2005, at a time when it was colonised by a non-indigenous Daphnia species. Zooplankton community composition changed during the study from one of rotifer dominance (e.g. Asplanchna, Polyarthra, Brachionus and Keratella specie...
Article
We tested the hypothesis that construction of lakes and ponds has facilitated both inter- and intracontinental invasions of calanoid copepod species. North Island, New Zealand. We sampled both natural and constructed lakes, ponds and reservoirs for calanoid copepods in the North Island, New Zealand. Species records were supplemented by examining hi...
Article
Full-text available
This report was commissioned by Environment Waikato to examine the available methods for internal (bottom sediment) nutrient removal and their suitability for application in the Waikato peat lakes. Lakes Ngaroto, Kainui, Rotomanuka and Cameron were chosen as focus lakes for the study, based on existing restoration objectives and recreational and co...
Article
Full-text available
The distribution of macroinvertebrates was investigated among sites within five geothermally influenced and two non- or minimally-influenced streams in the Taupo Volcanic Zone, New Zealand, to examine the responses of communities to broad environmental gradients within and among habitats. To date, examination of geothermal stream macroinvertebrates...
Article
Full-text available
Global ports are hubs for industrial activities and trade. In consequence, sediments and water in these areas are often contaminated by an array of chemicals. Sediments also harbour both living, active stages and various diapausing or resting stages of biota. International shipping activities move sediments containing these biotic stages around the...
Article
Full-text available
We present the first records from New Zealand of three non‐indigenous freshwater Zooplankton species: the Japanese Sinodiaptomus valkanovi, North American Skistodiaptomus pallidus (Copepoda), and Daphnia dentifera (Anomopoda). Owing to their geographic origins, introduction to New Zealand by natural passive dispersal is highly unlikely. Skistodiapt...
Article
Full-text available
We examined the invasion risk posed by active invertebrates and their diapausing stages (e.g. resting eggs, quiescent adults) carried in residual sediment and water of non-ballasted ships to Chesapeake Bay. Many taxa were recorded that are not native to Chesapeake Bay, supporting the contention that residual ballast represents an invasion vector of...
Article
Full-text available
Relationships between phytoplankton assemblages and lake trophic state, mixing regime and light climate were investigated in 40 North Island, New Zealand, lakes. We tested the hypothesis that mixing regime is more important than trophic state or light climate in determining the community composition of phytoplankton assemblages which were represent...
Article
Many transoceanic vessels enter the Great Lakes carrying residual ballast water and sediment that harbours live animals and diapausing eggs. In this study, we examine the potential for sodium hypochlorite (NaOCl) to reduce the risk of species introductions from diapausing invertebrate eggs in residual ballast sediment. We collected sediment from th...
Article
Full-text available
Relationships between phytoplankton assemblages and lake trophic state, mixing regime and light climate were investigated in 40 North Island, New Zealand, lakes. We tested the hypothesis that mixing regime is more important than trophic state or light climate in determining the community composition of phytoplankton assemblages which were represent...
Article
Full-text available
Most ships entering the Great Lakes carry cargo and declare "no-ballast-on board" (NOBOB) status. Approximately 250 of these vessels annually load Great Lakes' ballast water when they offload inbound cargo and then discharge this water (which has now mixed with residual water previously present in the tanks) when they load outbound cargo. This proc...
Article
Full-text available
Ships that enter the Great Lakes laden with cargo carry only residual ballast water and sediment in ballast tanks. These ships are designated ‘no ballast on board’ (NOBOB) and constitute > 90% of inbound traffic. We conducted in situ experiments using emergence traps to assess the viability and the introduction potential of invertebrate diapausing...
Article
Full-text available
International trade is an important mechanism for global non-indigenous species introductions, which have had profound impacts on the biodiversity of aquatic ecosystems including the Laurentian Great Lakes. The best-documented vector by which non-indigenous species have entered the Great Lakes is ballast water discharged by transoceanic ships. A va...