title: Swimming capabilities of stoats and the threat to inshore sanctuaries

authors: King, Carolyn M.

subjects: stoat

abstract: Stoats (Mustela erminea) are small carnivorous mammals which were introduced into New Zealand in the late 19th century, and have now become widespread invasive pests. Stoats have long been known to be capable of swimming to islands 1-1.5 km offshore. Islands further out have usually been assumed to be safe from invasion, therefore routine stoat monitoring on them has been considered un-necessary. Recent incursions, including a stoat found on Rangitoto Island (3 km offshore) in 2010, and another which was deduced to have reached Kapiti (5 km offshore) in 2009, along with distribution modelling and genetic studies, strongly support the proposition that stoats can swim much further than 1.5 km. Acceptance of this hypothesis depends on estimating the probability that such small animals could indeed swim so far unaided. This paper reports the results of a project designed to assist this debate by recording the paddling action, speed and minimal endurance of nine stoats observed (once each) swimming against an endless current in a flume at the Aquatic Research Centre, University of Waikato. Four of the five males and two of the four females could hold a position for at least five minutes against the maximum current available, averaging 1.36 ± 0.336 km/h. In steady swimming against a current of c. 1 km/hr, they all used a rapid quadripedal paddling action (averaging 250 strokes/min, stronger with the spread forepaws). Four of the nine swam strongly for >1 h, including one female who covered 1.8 km in nearly 2 h non- stop. Results from such artificial conditions cannot be conclusive, but support suggestions that wild stoats could indeed swim much further than 1.5 km, hence we conclude that the “risk zone” for  stoat reinvasions of inshore islands has been seriously under-estimated.

text: Swimming capabilities of stoats and the threat to inshore sanctuaries Stoats (Mustela erminea) are small carnivorous mammals which were introduced into New Zealand in the late 19th century, and have now become widespread invasive pests. Stoats have long been known to be capable of swimming to islands 1-1.5 km offshore. Islands further out have usually been assumed to be safe from invasion, therefore routine stoat monitoring on them has been considered un-necessary. Recent incursions, including a stoat found on Rangitoto Island (3 km offshore) in 2010, and another which was deduced to have reached Kapiti (5 km offshore) in 2009, along with distribution modelling and genetic studies, strongly support the proposition that stoats can swim much further than 1.5 km. Acceptance of this hypothesis depends on estimating the probability that such small animals could indeed swim so far unaided. This paper reports the results of a project designed to assist this debate by recording the paddling action, speed and minimal endurance of nine stoats observed (once each) swimming against an endless current in a flume at the Aquatic Research Centre, University of Waikato. Four of the five males and two of the four females could hold a position for at least five minutes against the maximum current available, averaging 1.36 ± 0.336 km/h. In steady swimming against a current of c. 1 km/hr, they all used a rapid quadripedal paddling action (averaging 250 strokes/min, stronger with the spread forepaws). Four of the nine swam strongly for >1 h, including one female who covered 1.8 km in nearly 2 h non- stop. Results from such artificial conditions cannot be conclusive, but support suggestions that wild stoats could indeed swim much further than 1.5 km, hence we conclude that the “risk zone” for  stoat reinvasions of inshore islands has been seriously under-estimated.

year: 2014

title: Optimising the zoospore release, germination, development of gametophytes and formation of sporophytes of Ecklonia radiata

authors: Praeger, Christina

subjects: Cultivation

abstract: The kelp Ecklonia radiata has become a target for controlled cultivation. However, to date there are no standardised protocols for the hatchery stage of this species that result in high rates of germination, gametophyte development and transition to sporophytes. Therefore, the objective of this study was to quantify the effect of photoperiod, light intensity, temperature, nutrient media and use of  GeO2 on the key hatchery processes of germination, gametophyte development and transition to sporophytes in controlled laboratory experiments. Germination of E. radiata was high (≥ 85%) throughout the study, regardless of treatments. Temperature had a major effect on the length of gametophytes, which increased with increasing temperature. The formation of sporophytes was favoured when individuals were maintained under 17 °C continuously, while reduced by approximately 30% when using F/2 compared to PES nutrient media. Overall, the recommended conditions for the hatchery stage of E. radiata are to maintain cultures under a 12 h L:12 h D photoperiod at 17 °C as this resulted in higher germination rates, good gametophyte development and higher transition to sporophytes compared to other treatments. Moreover, the use of  GeO2 has to be limited to no more than 2 days as extended use has detrimental effects on the development of sporophytes. Finally, storage of sorus-bearing fronds of sporophytes up to 4 days after the collection from the field generally increased the number of released zoospores and is a simple mechanism to increase the fertility of brood stock.

text: Optimising the zoospore release, germination, development of gametophytes and formation of sporophytes of Ecklonia radiata The kelp Ecklonia radiata has become a target for controlled cultivation. However, to date there are no standardised protocols for the hatchery stage of this species that result in high rates of germination, gametophyte development and transition to sporophytes. Therefore, the objective of this study was to quantify the effect of photoperiod, light intensity, temperature, nutrient media and use of  GeO2 on the key hatchery processes of germination, gametophyte development and transition to sporophytes in controlled laboratory experiments. Germination of E. radiata was high (≥ 85%) throughout the study, regardless of treatments. Temperature had a major effect on the length of gametophytes, which increased with increasing temperature. The formation of sporophytes was favoured when individuals were maintained under 17 °C continuously, while reduced by approximately 30% when using F/2 compared to PES nutrient media. Overall, the recommended conditions for the hatchery stage of E. radiata are to maintain cultures under a 12 h L:12 h D photoperiod at 17 °C as this resulted in higher germination rates, good gametophyte development and higher transition to sporophytes compared to other treatments. Moreover, the use of  GeO2 has to be limited to no more than 2 days as extended use has detrimental effects on the development of sporophytes. Finally, storage of sorus-bearing fronds of sporophytes up to 4 days after the collection from the field generally increased the number of released zoospores and is a simple mechanism to increase the fertility of brood stock.

year: 2022-10

title: Taking Taniwha seriously

authors: Kingsbury, Justine

subjects: intercultural understanding

abstract: Taniwha are powerful water creatures in te ao Māori (the Māori world/worldview). Taniwha sometimes afect public works in Aotearoa New Zealand: for example, consultation between government agencies and tangata whenua (the people of the land) about proposed roading developments sometimes results in the route being moved to avoid the dwelling place of a taniwha. Mainstream media responses have tended to be hostile or mocking, as you might expect, since on the face of it the dominant western scientifc worldview has no place for beings like taniwha. However, in the 2020s, there appears to be an increased willingness to engage with te ao Māori. In this spirit, this paper proposes a way for non-Māori to begin to take taniwha more seriously, taking as its starting point the work of Dan Hikuroa on the practical usefulness of taniwha pūrākau (traditional narratives) in encoding information about natural hazards. The focus of this paper is narrow, but aspects of the strategy it proposes may be generalisable both to other aspects of te ao Māori and to other bicultural and multicultural contexts.

text: Taking Taniwha seriously Taniwha are powerful water creatures in te ao Māori (the Māori world/worldview). Taniwha sometimes afect public works in Aotearoa New Zealand: for example, consultation between government agencies and tangata whenua (the people of the land) about proposed roading developments sometimes results in the route being moved to avoid the dwelling place of a taniwha. Mainstream media responses have tended to be hostile or mocking, as you might expect, since on the face of it the dominant western scientifc worldview has no place for beings like taniwha. However, in the 2020s, there appears to be an increased willingness to engage with te ao Māori. In this spirit, this paper proposes a way for non-Māori to begin to take taniwha more seriously, taking as its starting point the work of Dan Hikuroa on the practical usefulness of taniwha pūrākau (traditional narratives) in encoding information about natural hazards. The focus of this paper is narrow, but aspects of the strategy it proposes may be generalisable both to other aspects of te ao Māori and to other bicultural and multicultural contexts.

year: 2022-11-10