title: Summer meltwater and spring sea ice primary production, light climate and nutrients in an Arctic estuary, Kangedussuaq, west Greenland

authors: Lund-Hansen, Lars Chresten

subjects: Science & Technology

abstract: The estuary is dominated by sea ice and snow cover from winter to spring, and a highly turbid meltwater plume during summer. The aims were to quantify the variability in optical conditions, inorganic nutrients, and primary production between these two extremes, and identify the drivers of variability. Data were obtained during a summer cruise along a transect in the estuary in August 2007, and a spring campaign on the ice in March 2011. The study comprises conductivity, temperature, and depth (CTD), K𝒹(PAR), K𝒹(λ), PAR transmittance, photic depth, chl-a, nutrients (NO₃, NO₂, NH₃, PO₄, and SiO₂), primary production, and sediment concentrations. PAR transmittance varied between 5% below snow and ice and 85% in clear water with 44% in turbid meltwater. Primary production rates were similar below the ice in March (76.8 mg C m⁻² d⁻¹) and in the highly turbid meltwater in August (94.8 mg C m⁻² d⁻¹), but higher (246.6 mg C m⁻² d⁻¹) at the mouth of the fjord. Meltwater inflow was the main driver of variability during summer and the snow and sea ice during spring. Under-ice primary production will increase three-fold with less snow on the sea ice, and the higher meltwater turbidity with increased melting of glacial ice and runoff will only reduce primary production slightly.

text: Summer meltwater and spring sea ice primary production, light climate and nutrients in an Arctic estuary, Kangedussuaq, west Greenland The estuary is dominated by sea ice and snow cover from winter to spring, and a highly turbid meltwater plume during summer. The aims were to quantify the variability in optical conditions, inorganic nutrients, and primary production between these two extremes, and identify the drivers of variability. Data were obtained during a summer cruise along a transect in the estuary in August 2007, and a spring campaign on the ice in March 2011. The study comprises conductivity, temperature, and depth (CTD), K𝒹(PAR), K𝒹(λ), PAR transmittance, photic depth, chl-a, nutrients (NO₃, NO₂, NH₃, PO₄, and SiO₂), primary production, and sediment concentrations. PAR transmittance varied between 5% below snow and ice and 85% in clear water with 44% in turbid meltwater. Primary production rates were similar below the ice in March (76.8 mg C m⁻² d⁻¹) and in the highly turbid meltwater in August (94.8 mg C m⁻² d⁻¹), but higher (246.6 mg C m⁻² d⁻¹) at the mouth of the fjord. Meltwater inflow was the main driver of variability during summer and the snow and sea ice during spring. Under-ice primary production will increase three-fold with less snow on the sea ice, and the higher meltwater turbidity with increased melting of glacial ice and runoff will only reduce primary production slightly.

year: 2018

title: Effects of turbidity and light intensity on foraging success of juvenile mandarin fish Siniperca chuatsi (Basilewsky)

authors: Li, Wei

subjects: foraging success

abstract: This study aimed to evaluate the effects of turbidity and light intensity on foraging success of juvenile mandarin fish Siniperca chuatsi. Predation on crucian carp Carassius auratus by juvenile mandarin fish was tested at five levels of turbidity combined with two light intensities, imitating daylight and night in two turbidity types. Foraging success was significantly lower in clay-induced turbidity than in algal-induced turbidity. In clay-induced turbidity trials, there was a slight but insignificant increase in foraging success of mandarin fish with increasing turbidity under lighted conditions. In algal-induced turbidity trials, there were no significant differences in foraging success of mandarin fish among turbidity levels at both light and dark levels, but at 80 NTU turbidity level, foraging success was lower than in all the other turbidity levels. There was no significant difference in foraging success at different turbidities under darkness. These results suggest that piscivory of mandarin fish is influenced by different turbidity types but is not significantly influenced by increased turbidity combined with decreased light intensity.

text: Effects of turbidity and light intensity on foraging success of juvenile mandarin fish Siniperca chuatsi (Basilewsky) This study aimed to evaluate the effects of turbidity and light intensity on foraging success of juvenile mandarin fish Siniperca chuatsi. Predation on crucian carp Carassius auratus by juvenile mandarin fish was tested at five levels of turbidity combined with two light intensities, imitating daylight and night in two turbidity types. Foraging success was significantly lower in clay-induced turbidity than in algal-induced turbidity. In clay-induced turbidity trials, there was a slight but insignificant increase in foraging success of mandarin fish with increasing turbidity under lighted conditions. In algal-induced turbidity trials, there were no significant differences in foraging success of mandarin fish among turbidity levels at both light and dark levels, but at 80 NTU turbidity level, foraging success was lower than in all the other turbidity levels. There was no significant difference in foraging success at different turbidities under darkness. These results suggest that piscivory of mandarin fish is influenced by different turbidity types but is not significantly influenced by increased turbidity combined with decreased light intensity.

year: 2013

title: Sharing, listening, learning and developing understandings of Kaupapa Māori research by engaging with two Māori communities involved in education.

authors: Kana, Fred

subjects: Kaupapa Maori research methodology

abstract: This paper is a culmination of common understandings that were elicited from two pieces of research: ‘The Impact of the BHP New Zealand Steel Mining on the Tangata Whenua and the Environment’ and ‘The Impact of Maori Medium Education within a Mainstream Secondary School on the Lives of its Participants, in particular the Teachers, Caregivers and Students’. It was at the conclusion of each research project and as a consequence of informal conversations and discussions that this paper evolved. The paper discusses shared understandings in the context of Kaupapa Māori research methodology and key findings from the two research projects.

text: Sharing, listening, learning and developing understandings of Kaupapa Māori research by engaging with two Māori communities involved in education. This paper is a culmination of common understandings that were elicited from two pieces of research: ‘The Impact of the BHP New Zealand Steel Mining on the Tangata Whenua and the Environment’ and ‘The Impact of Maori Medium Education within a Mainstream Secondary School on the Lives of its Participants, in particular the Teachers, Caregivers and Students’. It was at the conclusion of each research project and as a consequence of informal conversations and discussions that this paper evolved. The paper discusses shared understandings in the context of Kaupapa Māori research methodology and key findings from the two research projects.

year: 2006