The effect of UV radiation on habitat use of two species of intertidal fishes that inhabit the sa... more The effect of UV radiation on habitat use of two species of intertidal fishes that inhabit the same pools but exhibit different activity levels and diets was measured: the highly active omnivorous Girella laevifrons and the cryptic carnivorous Graus nigra. Individuals of each species were acclimated to a tank divided in three sections with different illumination; no light (NL), ultraviolet light (UV) and white light (WL), and the time spent and number of visits to each section were recorded. Although both species preferred the NL section, G. laevifrons spent more time in UV and less time in WL compared with G. nigra; G. laevifrons also displayed higher number of visits to UV, suggesting a different tendency in space use in response to UV exposure in intertidal fishes.
A Dynamic Energy Budget (DEB) model is applied to predict rapid metabolic shifts in an ecological... more A Dynamic Energy Budget (DEB) model is applied to predict rapid metabolic shifts in an ecologically important krill, Nyctiphanes australis, in response to temperature and ultraviolet radiation (UVR). Specifically, we predict changes in fatty acids, amino acids and respiration rate in response to several light and temperature treatments. Environmental variability can alter the metabolic equilibrium and the mechanisms marine ectotherms used to obtain energy, which is a topical point given the current level of environmental change. Environmental variability also includes multiple stressors, which can have additive, antagonistic or synergistic effects on metabolism. In consequence, disentangling and quantifying the effects of multiple stressors on metabolism and the energy balance of ecthothermal species, such as krill, can be challenging. Here we apply a DEB model to direct measurements of fatty acids, amino acids and respiration rate of krill experimentally exposed simultaneously to s...
. Light is an important regulator of photo-chemical and photo-biological processes in coastal are... more . Light is an important regulator of photo-chemical and photo-biological processes in coastal areas. However, understanding how the atmosphere-ocean interaction drives changes in the amount of light entering coastal waters and how changes in the underwater light environment influence the biological characteristic of coastal water can be challenging due to the complex oceanographic dynamic of these areas. Here, we empirically describe the seasonal relationships between meteorological and oceanographic variables over a three year period and quantify the effect light have on the productivity of a coastal area off the Otago coast, New Zealand, through the application of an oceanographic-biological model. The model quantifies changes in the production-biomass ratio (PP / B) (i.e. rate of production of organic matter from phytoplankton produced per unit of total organic biomass) using measurements of the underwater attenuation coefficient, particulate organic carbon, chlorophyll-a and sea temperature. The sensitivity of the model to input data was estimated by comparing the PP / B ratio predicted from Chl a concentrations derived from field measurements of the attenuation coefficients of PAR light Kd (m−1) and Chl a concentrations derived from remote sensing data of Kd (m−1). The results presented here indicate a mild increment in solar radiation partially driven by increased wind speeds and reduction of cloud cover, ultimately producing small increments in the amount of solar radiation penetrating the water column, especially during summer. The model formulated, predict important seasonal shifts in the PP/B ratio. These shifts are driven by the rate at which light decays and likely modulated by the frequency of wind speeds that favour increments of the thermoclines depth and an increment of sea surface temperatures in the area.
The genus Nyctiphanes G.O. Sars, 1883 (Euphausiacea, Euphausiidae) includes four extant species. ... more The genus Nyctiphanes G.O. Sars, 1883 (Euphausiacea, Euphausiidae) includes four extant species. These species are a conspicuous component of trophic webs of coastal marine ecosystems due to their abundance, the formation of dense aggregations, swarms, and schools, fast growth, and high reproductive rates. They dominate the bulk biomass in eutrophic Eastern Boundaries System and subtropical mesotrophic habitats, with estimates of 30–40% of the total zooplankton biomass. Species of Nyctiphanes are efficient omnivores and conversely prey for a large number of zooplanktonic and nektonic species. We review current knowledge of the biogeography, reproductive biology, physiology, biochemistry, ecology, and parasitology of the four species of Nyctiphanes. Most published information on Nyctiphanes focuses on the two species from the Pacific Ocean, N. australis G.O. Sars, 1883 and N. simplex Hansen, 1911, and considerably less is known on the biology and ecology of N. couchii (Bell, 1853) a...
The effect of UV radiation on habitat use of two species of intertidal fishes that inhabit the sa... more The effect of UV radiation on habitat use of two species of intertidal fishes that inhabit the same pools but exhibit different activity levels and diets was measured: the highly active omnivorous Girella laevifrons and the cryptic carnivorous Graus nigra. Individuals of each species were acclimated to a tank divided in three sections with different illumination; no light (NL), ultraviolet light (UV) and white light (WL), and the time spent and number of visits to each section were recorded. Although both species preferred the NL section, G. laevifrons spent more time in UV and less time in WL compared with G. nigra; G. laevifrons also displayed higher number of visits to UV, suggesting a different tendency in space use in response to UV exposure in intertidal fishes.
A Dynamic Energy Budget (DEB) model is applied to predict rapid metabolic shifts in an ecological... more A Dynamic Energy Budget (DEB) model is applied to predict rapid metabolic shifts in an ecologically important krill, Nyctiphanes australis, in response to temperature and ultraviolet radiation (UVR). Specifically, we predict changes in fatty acids, amino acids and respiration rate in response to several light and temperature treatments. Environmental variability can alter the metabolic equilibrium and the mechanisms marine ectotherms used to obtain energy, which is a topical point given the current level of environmental change. Environmental variability also includes multiple stressors, which can have additive, antagonistic or synergistic effects on metabolism. In consequence, disentangling and quantifying the effects of multiple stressors on metabolism and the energy balance of ecthothermal species, such as krill, can be challenging. Here we apply a DEB model to direct measurements of fatty acids, amino acids and respiration rate of krill experimentally exposed simultaneously to s...
. Light is an important regulator of photo-chemical and photo-biological processes in coastal are... more . Light is an important regulator of photo-chemical and photo-biological processes in coastal areas. However, understanding how the atmosphere-ocean interaction drives changes in the amount of light entering coastal waters and how changes in the underwater light environment influence the biological characteristic of coastal water can be challenging due to the complex oceanographic dynamic of these areas. Here, we empirically describe the seasonal relationships between meteorological and oceanographic variables over a three year period and quantify the effect light have on the productivity of a coastal area off the Otago coast, New Zealand, through the application of an oceanographic-biological model. The model quantifies changes in the production-biomass ratio (PP / B) (i.e. rate of production of organic matter from phytoplankton produced per unit of total organic biomass) using measurements of the underwater attenuation coefficient, particulate organic carbon, chlorophyll-a and sea temperature. The sensitivity of the model to input data was estimated by comparing the PP / B ratio predicted from Chl a concentrations derived from field measurements of the attenuation coefficients of PAR light Kd (m−1) and Chl a concentrations derived from remote sensing data of Kd (m−1). The results presented here indicate a mild increment in solar radiation partially driven by increased wind speeds and reduction of cloud cover, ultimately producing small increments in the amount of solar radiation penetrating the water column, especially during summer. The model formulated, predict important seasonal shifts in the PP/B ratio. These shifts are driven by the rate at which light decays and likely modulated by the frequency of wind speeds that favour increments of the thermoclines depth and an increment of sea surface temperatures in the area.
The genus Nyctiphanes G.O. Sars, 1883 (Euphausiacea, Euphausiidae) includes four extant species. ... more The genus Nyctiphanes G.O. Sars, 1883 (Euphausiacea, Euphausiidae) includes four extant species. These species are a conspicuous component of trophic webs of coastal marine ecosystems due to their abundance, the formation of dense aggregations, swarms, and schools, fast growth, and high reproductive rates. They dominate the bulk biomass in eutrophic Eastern Boundaries System and subtropical mesotrophic habitats, with estimates of 30–40% of the total zooplankton biomass. Species of Nyctiphanes are efficient omnivores and conversely prey for a large number of zooplanktonic and nektonic species. We review current knowledge of the biogeography, reproductive biology, physiology, biochemistry, ecology, and parasitology of the four species of Nyctiphanes. Most published information on Nyctiphanes focuses on the two species from the Pacific Ocean, N. australis G.O. Sars, 1883 and N. simplex Hansen, 1911, and considerably less is known on the biology and ecology of N. couchii (Bell, 1853) a...
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