title: The parasite release hypothesis and the success of invasive fish in New Zealand

authors: Zhang, Keshi

subjects: parasite release hypothesis

abstract: Non-indigenous species are commonly released from their native enemies, including parasites, when they are introduced into new geographical areas. This has been referred to as the enemy release hypothesis and more strictly as the parasite release hypothesis. The loss of parasites is commonly inferred to explain the invasiveness of non-indigenous species. I examined parasite release in New Zealand non-indigenous freshwater fishes. A literature review was undertaken in order to collate lists of the known parasite fauna of 20 New Zealand non-indigenous freshwater fish species. Records were collated from their home range, New Zealand, and some other introduced ranges, to determine whether these species have a reduced parasite diversity in the New Zealand and other introduced ranges. Five non-indigenous freshwater fish, mosquitofish (Gambusia affinis), rudd (Scardinius erythrophthalmus), goldfish (Carassius auratus), koi carp (Cyprinus carpio) and catfish (Ameiurus nebulosus), and one native freshwater fish, common bullies (Gobiomorphus cotidianus), were sampled and examined for metazoan parasites. Mosquitofish and bullies, of similar size and habitat, were examined with greater intensity than the other species. Based on the literature review and fish examination, I found that the non-indigenous freshwater fish in New Zealand have seemingly lost their parasites. Being “lost overboard” is likely to have caused the loss of some parasites as most of the additional hosts required for non-indigenous parasites are no present in New Zealand. However, the loss of most of mosquitofish’s parasites is likely due to “missing the boat”, as introduction into New Zealand was a two-step process, from their native range in North America, via Hawaii, before release in New Zealand. Additionally, other hosts required for parasites of mosquitofish are not present in New Zealand. The native common bullies were found to harbour more parasites than the non-indigenous mosquitofish. Two parasites were found from common bullies, the cysts of the trematodes Eustrongylides ignotus and Telogaster opisthorchis, and no parasites were found on mosquitofish. A lack of spillback of Eustrongylides ignotus from bullies to mosquitofish, despite being parasititised by this species in its native range, may due to mosquitofish not being able to feed on intermediate the hosts present in New Zealand. The establishment and spread of non-indigenous fish in New Zealand waters is likely not the sole result of parasite release, but given their apparent reduction or lack of parasites, it may be a factor contributing to their success.

text: The parasite release hypothesis and the success of invasive fish in New Zealand Non-indigenous species are commonly released from their native enemies, including parasites, when they are introduced into new geographical areas. This has been referred to as the enemy release hypothesis and more strictly as the parasite release hypothesis. The loss of parasites is commonly inferred to explain the invasiveness of non-indigenous species. I examined parasite release in New Zealand non-indigenous freshwater fishes. A literature review was undertaken in order to collate lists of the known parasite fauna of 20 New Zealand non-indigenous freshwater fish species. Records were collated from their home range, New Zealand, and some other introduced ranges, to determine whether these species have a reduced parasite diversity in the New Zealand and other introduced ranges. Five non-indigenous freshwater fish, mosquitofish (Gambusia affinis), rudd (Scardinius erythrophthalmus), goldfish (Carassius auratus), koi carp (Cyprinus carpio) and catfish (Ameiurus nebulosus), and one native freshwater fish, common bullies (Gobiomorphus cotidianus), were sampled and examined for metazoan parasites. Mosquitofish and bullies, of similar size and habitat, were examined with greater intensity than the other species. Based on the literature review and fish examination, I found that the non-indigenous freshwater fish in New Zealand have seemingly lost their parasites. Being “lost overboard” is likely to have caused the loss of some parasites as most of the additional hosts required for non-indigenous parasites are no present in New Zealand. However, the loss of most of mosquitofish’s parasites is likely due to “missing the boat”, as introduction into New Zealand was a two-step process, from their native range in North America, via Hawaii, before release in New Zealand. Additionally, other hosts required for parasites of mosquitofish are not present in New Zealand. The native common bullies were found to harbour more parasites than the non-indigenous mosquitofish. Two parasites were found from common bullies, the cysts of the trematodes Eustrongylides ignotus and Telogaster opisthorchis, and no parasites were found on mosquitofish. A lack of spillback of Eustrongylides ignotus from bullies to mosquitofish, despite being parasititised by this species in its native range, may due to mosquitofish not being able to feed on intermediate the hosts present in New Zealand. The establishment and spread of non-indigenous fish in New Zealand waters is likely not the sole result of parasite release, but given their apparent reduction or lack of parasites, it may be a factor contributing to their success.

year: 2012

title: Living alone as a lifestyle among older people in New Zealand

authors: Koopman-Boyden, Peggy G.

abstract: This paper discusses living alone as a lifestyle among older people in New Zealand, including population trends and living a meaningful life.

text: Living alone as a lifestyle among older people in New Zealand This paper discusses living alone as a lifestyle among older people in New Zealand, including population trends and living a meaningful life.

year: 2014

title: E hoki mai nei ki te ūkaipō | Return to your place of nourishment [Gallagher Academy of Performing Arts]

authors: Apiata, Hāwea

abstract: E hoki mai nei ki te ūkaipō | Return to your Place of Nourishment brings together works by four wāhine Māori artists which explore narratives of pakanga|conflict through toi|art. This exhibition aims to create a dialogic space in which the artworks reflect and challenge the current troubled economic and political landscape. In this show, the four artists weave together their unique practices and stories to present a cohesive yet diverse examination of conflicts, with a particular focus on the artists’ own whānau and hapū narratives.

Ultimately, this collection of works interrogates political strategies that have exploited division and discord through carefully curated histories. This collection is also a reclamation of those narratives and histories by descendants who live in the aftermath of their ancestors’ mamae | pain.

text: E hoki mai nei ki te ūkaipō | Return to your place of nourishment [Gallagher Academy of Performing Arts] E hoki mai nei ki te ūkaipō | Return to your Place of Nourishment brings together works by four wāhine Māori artists which explore narratives of pakanga|conflict through toi|art. This exhibition aims to create a dialogic space in which the artworks reflect and challenge the current troubled economic and political landscape. In this show, the four artists weave together their unique practices and stories to present a cohesive yet diverse examination of conflicts, with a particular focus on the artists’ own whānau and hapū narratives.

Ultimately, this collection of works interrogates political strategies that have exploited division and discord through carefully curated histories. This collection is also a reclamation of those narratives and histories by descendants who live in the aftermath of their ancestors’ mamae | pain.

year: 2024