Blooms and subsurface phytoplankton layers on the Scotian Shelf: Insights from profiling gliders

Ross, Tetjana; Craig, Susanne E.; Comeau, Adam; Davis, Richard F.; Dever, Mathieu; Beck, Matthew

doi:10.1016/j.jmarsys.2017.03.007

Cited by 21 publications

(14 citation statements)

References 46 publications

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“…Various in situ optical observations from shipborne operations and autonomous vehicles and floats are essential to develop, improve, and evaluate OCRS algorithms as well as provide information necessary to link surface ocean processes with those occurring at greater depths (Martin et al, ; Ross et al, ). Fluorometric measurements are the most common method for rapid in situ estimation of chlorophyll a concentration, Chla , and its vertical, spatial, and temporal variability, although this method is biased by decrease in fluorescence quantum yield due to phytoplankton photoinhibition resulting from the stronger irradiance near the surface (Cullen, ).…”

Section: Introductionmentioning

confidence: 99%

Bio‐optical Properties of Surface Waters in the Atlantic Water Inflow Region off Spitsbergen (Arctic Ocean)

et al. 2019

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Bio‐optical properties of surface waters were characterized off western and northern Spitsbergen in the summers of 2013, 2014, and 2015. We observed statistically significant year‐to‐year differences in spatial distribution of spectral absorption (a(λ)) and beam attenuation (c(λ)). Highest a(λ) and c(λ) were located in the frontal zone between water masses and co‐varied strongly with chlorophyll a fluorescence. Phytoplankton pigments dominated the absorption budget at 443 nm (50%). The contribution of chromophoric dissolved organic matter to total nonwater absorption was highest at 412 nm (42%), and detrital absorption contributed most at 550 nm (37%). Almost all inherent optical properties, except chromophoric dissolved organic matter, were highly correlated with the chlorophyll a concentration (Chla, R2 > 0.81). Relationships between Chla and the particulate and phytoplankton pigments absorption coefficients at 443 and 676 nm were characterized by significant determination coefficients (R2 > 0.73). The phytoplankton pigments line height absorption aLH(676) was found to be the most reliable optical proxy for determination of Chla, compared to total nonwater absorption, apg(676), and stimulated in situ chlorophyll a fluorescence intensity, IChla. In the presence of sea ice melt the water column was stratified and the vertical distribution of inherent optical properties was characterized by a surface minimum followed by a distinct subsurface maximum, aligned with a subsurface chlorophyll a maximum. We surmise that prevailing regional wind patterns affect sea ice and surface drift in central Fram Strait, and thus the location of sea ice meltwater, which affects the vertical stratification and occurrence of subsurface chlorophyll a maximum.

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Section: Introductionmentioning

confidence: 99%

Bio‐optical Properties of Surface Waters in the Atlantic Water Inflow Region off Spitsbergen (Arctic Ocean)

et al. 2019

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“…There is a suggestion of this summertime SCML in the climatological data from the region (Fig. 2iv) and in a recent glider study of the Scotian Shelf by Ross et al (2017).…”

Section: Oceanographic Settingmentioning

confidence: 56%

“…2iv), demonstrates the intensity of the spring bloom during the months of March-April. The timing of the bloom varies between these two months depending on several factors including the onset of stratification and availability of light (Shadwick et al, 2010;Greenan et al, 2004;Ross et al, 2017). Once the phytoplankton bloom consumes the available nitrate, the assemblage is taken over by smaller phytoplankton that prosper in the higher-temperature, lowernutrient conditions (Craig et al, 2015;Li et al, 2006).…”

Section: Oceanographic Settingmentioning

confidence: 99%

Hurricane Arthur and its effect on the short-term variability of <i>p</i>CO<sub>2</sub> on the Scotian Shelf, NW Atlantic

et al. 2018

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Abstract. The understanding of the seasonal variability of carbon cycling on the Scotian Shelf in the NW Atlantic Ocean has improved in recent years; however, very little information is available regarding its short-term variability. In order to shed light on this aspect of carbon cycling on the Scotian Shelf we investigate the effects of Hurricane Arthur, which passed the region on 5 July 2014. The hurricane caused a substantial decline in the surface water partial pressure of CO 2 (pCO 2 ), even though the Scotian Shelf possesses CO 2 -rich deep waters. High-temporal-resolution data of moored autonomous instruments demonstrate that there is a distinct layer of relatively cold water with low dissolved inorganic carbon (DIC) slightly above the thermocline, presumably due to a sustained population of phytoplankton. Strong storm-related wind mixing caused this cold intermediate layer with high phytoplankton biomass to be entrained into the surface mixed layer. At the surface, phytoplankton begin to grow more rapidly due to increased light. The combination of growth and the mixing of low DIC water led to a short-term reduction in the partial pressure of CO 2 until wind speeds relaxed and allowed for the restratification of the upper water column. These hurricane-related processes caused a (net) CO 2 uptake by the Scotian Shelf region that is comparable to the spring bloom, thus exerting a major impact on the annual CO 2 flux budget.

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“…Female grey seals have shown both diel variability in dive depths associated with movement of prey within the water column [42] and a dietary niche indicating that they consume a higher proportion of prey species that forage pelagically [43,62]. While this provides a potential explanation for these results, it is possible that a combination of other factors may be influential (e.g., relationship between T 50 and chl-a [51]).…”

Section: Association Of Behavioural States With Oceanographic Conditionsmentioning

confidence: 99%

Foraging behaviour of a continental shelf marine predator, the grey seal (Halichoerus grypus), is associated with in situ, subsurface oceanographic conditions

et al. 2020

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Background The heterogeneous oceanographic conditions of continental shelf ecosystems result in a three-dimensionally patchy distribution of prey available to upper-trophic level predators. The association of bio-physical conditions with movement patterns of large marine predators has been demonstrated in diverse taxa. However, obtaining subsurface data that are spatio-temporally relevant to the decisions made by benthically-foraging species can be challenging. Methods Between 2009 and 2015, grey seals were captured on Sable Island, Nova Scotia, Canada during summer and fall and instrumented with high-resolution archival GPS tags. These tags recorded location data as well as depth (m), temperature (°C), and light level measurements during dives, until animals returned to the haulout site to breed. Hidden Markov models were used to predict apparent foraging along movement tracks for 79 individuals (59 females, 20 males) every 3 h. In situ measurements were used to estimate chlorophyll-a concentration (mg m− 3) and temperature within the upper-water column (50 m) and temperature and depth at the bottom of dives. As chlorophyll-a could only be estimated from 10:00 to 14:00 AST for dive depths ≥50 m, we formulated two generalized linear mixed-effects models to test the association of predicted grey seal behavioural states with oceanographic conditions and phytoplankton biomass: the first representing conditions of the upper-water column likely to influence primary productivity, and a second model including environmental conditions encountered by grey seals at the bottom of dives, when seals were more likely to be foraging. Results Predicted grey seal behavioural states were associated with fine-scale chlorophyll-a concentrations and other environmental conditions they encountered across the continental shelf. In the Water Column Model, season had no influence on the probability of observing apparent foraging, but chlorophyll-a, upper-water column temperature, and sex did, with females having a greater probability of foraging than males. In the Bottom Conditions Model, again season had no influence on the probability of apparent foraging, but females were over twice as likely as males to be foraging. Conclusions The results of this study highlight the value of in situ measurements of oceanographic properties that can be collected at high temporal resolution by animal-borne data loggers. These data provide insight into how inferred behavioural decisions made by large marine predators, such as the grey seal, may be influenced by fine-scale oceanographic conditions.

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Blooms and subsurface phytoplankton layers on the Scotian Shelf: Insights from profiling gliders

Cited by 21 publications

References 46 publications

Bio‐optical Properties of Surface Waters in the Atlantic Water Inflow Region off Spitsbergen (Arctic Ocean)

Bio‐optical Properties of Surface Waters in the Atlantic Water Inflow Region off Spitsbergen (Arctic Ocean)

Hurricane Arthur and its effect on the short-term variability of <i>p</i>CO<sub>2</sub> on the Scotian Shelf, NW Atlantic

Foraging behaviour of a continental shelf marine predator, the grey seal (Halichoerus grypus), is associated with in situ, subsurface oceanographic conditions

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Blooms and subsurface phytoplankton layers on the Scotian Shelf: Insights from profiling gliders

Cited by 21 publications

References 46 publications

Bio‐optical Properties of Surface Waters in the Atlantic Water Inflow Region off Spitsbergen (Arctic Ocean)

Bio‐optical Properties of Surface Waters in the Atlantic Water Inflow Region off Spitsbergen (Arctic Ocean)

Hurricane Arthur and its effect on the short-term variability of &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; on the Scotian Shelf, NW Atlantic

Foraging behaviour of a continental shelf marine predator, the grey seal (Halichoerus grypus), is associated with in situ, subsurface oceanographic conditions

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Hurricane Arthur and its effect on the short-term variability of <i>p</i>CO<sub>2</sub> on the Scotian Shelf, NW Atlantic