Measuring the effects of bivalve mariculture on water quality in northern New Zealand using 15 years of MODIS-Aqua satellite observations

Pinkerton, Matt; Gall, Mark; Wood, Simon N.; Zeldis, John

doi:10.3354/aei00288

Cited by 18 publications

(12 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, the underway pCO 2 surveys surrounding the large suspended mussel farms in the eastern Firth (Figure 2C) showed no clear signal of pCO 2 modification in proximity to the farms, with respect to overall variability of pCO 2 over the larger Firth/Hauraki Gulf area. This was consistent with the remote sensing studies of Pinkerton et al (2018) that showed negligible water quality (chl-a and turbidity) effects of those farms, arising as a consequence of their very high water flushing rates. Water-column average variations of DIC concentration were consistent with variations of column-average net DIC flux calculated by the mass-balance analysis of Zeldis and Swaney (2018), made using nutrient, salinity and hydrometric data collected during the present study.…”

Section: Attributing Factors Controlling Carbonate and Oxygen Variationsupporting

confidence: 91%

Attributing Controlling Factors of Acidification and Hypoxia in a Deep, Nutrient-Enriched Estuarine Embayment

et al. 2022

View full text Add to dashboard Cite

Measuring and attributing controlling factors of acidification and hypoxia are essential for management of coastal ecosystems affected by those stressors. We address this using surveys in the Firth of Thames, a deep, seasonally stratified estuarine embayment adjoing the Hauraki Gulf in northern Aotearoa/New Zealand. The Firth’s catchment has undergone historic land-use intensification transforming it from native forest cover to dominance by pastoral use, increasing its riverine total nitrogen loading by ∼82% over natural levels and switching it’s predominate loading source from offshore to the catchment. We hypothesised that seasonal variation in net ecosystem metabolism [NEM: dissolved inorganic carbon (DIC) uptake/release] will be a primary factor determining carbonate and oxic responses in the Firth, and that organic matter involved in the metabolism will originate primarily by fixation within the Firth system and be driven by catchment dissolved inorganic nitrogen (DIN) loading. Seasonal ship-based and biophysical mooring surveys across the Hauraki Gulf and Firth showed depressed pH and O2 reaching pH ∼7.8 and O2 ∼4.8 mg L–1 in autumn in the inner Firth, matched by shoreward increasing nutrient loading, phytoplankton, organic matter, gross primary production (GPP) and apparent O2 utilization. A carbonate system deconvolution of the ship survey data, combined with other ship survey and mooring results, showed how CO2 partial pressure responded to seasonal shifts in temperature, NEM, phytoplankton sinking and mineralisation and water column stratification, that underlay the late-season expression of acidification and hypoxia. This aligned with seasonal shifts in net DIC fluxes determined in a coincident nutrient mass-balance analysis, showing near-neutral fluxes from spring to summer, but respiratory NEM from summer to autumn. Particulate C:N and ratios of organic C fixed by Firth GPP to that from river inputs (∼29- to 100-fold in summer and autumn) showed that the dominant source of organic matter fuelling heterotrophy in autumn was autochthonous GPP, driven by riverine DIN loading. The results signified the sensitivity of deep, long-residence time, seasonally stratifying estuaries to acidification and hypoxia, and are important for coastal resource management, including aquaculture developments and catchment runoff limit-setting for maintenance of ecosystem health.

show abstract

Section: Attributing Factors Controlling Carbonate and Oxygen Variationsupporting

confidence: 91%

Attributing Controlling Factors of Acidification and Hypoxia in a Deep, Nutrient-Enriched Estuarine Embayment

et al. 2022

View full text Add to dashboard Cite

show abstract

“…riverine influence along the southern New Zealand coast and large-scale land-use changes (Schiel and Howard-Williams, 2016;Stevens et al, 2021) and the coastal focus of this study. While the chl-a concentration (Pinkerton et al, 2018) and water clarity algorithms used in this study have been developed to better account for the often turbid waters of southern New Zealand, these case-2 coastal waters present challenges for determining metrics of both light availability (K d ) and phytoplankton biomass. However, the utility of remote sensing to retrospectively assess the effects of multiple physical and biotic parameters on kelp beds has great utility to better understand the interaction between local and global scale stressors.…”

Section: Discussionmentioning

confidence: 99%

“…Here, we used an average of values found for oceanic phytoplankton (Bricaud et al, 1995;Bissett et al, 1997), and measurements in the lower reaches of New Zealand rivers and estuaries. We blended the QAA-chl-a and the MODIS-default chl-a product (NASA, 2018) using a logistic-scaling of bbp(555) (Pinkerton et al, 2018).…”

Section: Chlorophyll-amentioning

confidence: 99%

“…The diffuse downwelling attenuation coefficient in the Photosynthetically Available Radiation (PAR range, 400-700 nm), K d (m −1 ) was used as our measure of water clarity. Values of K d were estimated from MODIS-Aqua measurements of ocean color, processed to inherent optical properties using the QAA algorithm (Lee et al, 2002(Lee et al, , 2009 following the methodology of Pinkerton et al (2018). From these IOPs, we estimated the diffuse attenuation coefficient in the PAR range as Lee et al (2005) and Shi and Wang (2007).…”

Section: Satellite Estimate Of the Downward Attenuation Coefficient Of Light (K D )mentioning

confidence: 99%

“…The temporal resolution of the product for the study region is 1-2 measurements daily. Values of K d were extracted from the dataset around kelp forests and averaged monthly to provide a dataset with low quantities of missing data (Pinkerton et al, 2018).…”

Section: Satellite Estimate Of the Downward Attenuation Coefficient Of Light (K D )mentioning

confidence: 99%

See 2 more Smart Citations

Loss of Giant Kelp, Macrocystis pyrifera, Driven by Marine Heatwaves and Exacerbated by Poor Water Clarity in New Zealand

et al. 2021

View full text Add to dashboard Cite

Marine heatwaves (MHW) are becoming stronger and more frequent across the globe. MHWs affect the thermal physiology of all biological organisms, but wider ecosystem effects are particularly impactful when large habitat-forming foundation species such as kelps are affected. Many studies on impacts from MHWs on kelps have focused on temperature effects in isolation, except for a few studies that have integrated co-occurring stress from grazers, wave exposure and nutrient limitation. It is likely that many stressors act in concert with MHWs and exacerbate their effects. Here we analyzed satellite images over 60 months to assess temporal changes in abundance of surface canopies of the giant kelp Macrocystis pyrifera in the New Zealand coastal zone. The analysis encompassed the most extreme MHW on record (2017/18), across a 6° latitudinal gradient of four regions southward from the northern distributional limit of Macrocystis along mainland New Zealand. We tested the association of surface canopy cover of Macrocystis with sea surface temperature, temperature anomalies, chlorophyll-a (a proxy for nutrient availability) and water clarity (diffuse attenuation coefficient). We found a reduced cover of Macrocystis across all regions during and after the 2017/18 MHW, with least impact at the most southern region where the maximum temperatures did not exceed 18°C. There was also an important and significant interaction between temperature and water clarity, showing that temperature-induced kelp loss was greater when water clarity was poor. These results show that notable negative effects occurred across the coastal range of this foundation species and highlight the importance of studying MHW effects across latitudinal gradients and in concert with other co-occurring stressors.

show abstract

The legacies of land clearance and trophic downgrading accumulate to affect structure and function of kelp forests

et al. 2022

View full text Add to dashboard Cite

Aotearoa New Zealand is the last major landmass settled by people, and therefore provides a recent record of ecological legacy effects in the coastal zone. Large-scale land clearances of forests accelerated over the last century, affecting the concentration of suspended sediments, light environment, and nutrient composition on rocky reefs, and consequently the distribution, abundance, and composition of algal forests. The environmental effects were compounded in many places by overfishing and long-term declines of large predatory species, often leading to proliferation and extensive grazing by sea urchins. In this study, we examine these processes in three biogeographic regions that have been differentially affected by ecological legacy effects. The study was based on the depth-specific associations between sea urchins (Evechinus chloroticus) and the common kelp (Ecklonia radiata) from multiple sites within each region, some of which were sampled over two decades within no-take marine reserves and in actively fished areas. Satellite-derived estimates of water-column properties were used as proxies for the relative effects of coastal sedimentation on kelp forest habitats. We then used an information-theoretic framework to assess the relative factor weightings of marine reserve effects on urchin density, total suspended solids (TSS), and regional urchin density on the depth-specific density of Ecklonia radiata. The fishing effects were significant within and outside of reserves in the northern and central regions, but the effect sizes were by far strongest in the northern region. In the central region characterized by extensive land clearance and forestry combined with high coastal retention of water, the concentration of TSS had a major influence on the depth distribution of kelp, confining it to shallow water (<10-m depth) in small patches where urchins did not overgraze. These patterns are in sharp contrast to the small marine reserve effects and deep distribution of Ecklonia radiata in the southern region, which has intact native forested catchments, comparatively low fishing pressure, and a large regional network of marine reserves. The results highlight important differences in how centuries-old legacies of land clearance and exploitation affect regional-scale

show abstract

Measuring the effects of bivalve mariculture on water quality in northern New Zealand using 15 years of MODIS-Aqua satellite observations

Cited by 18 publications

References 38 publications

Attributing Controlling Factors of Acidification and Hypoxia in a Deep, Nutrient-Enriched Estuarine Embayment

Attributing Controlling Factors of Acidification and Hypoxia in a Deep, Nutrient-Enriched Estuarine Embayment

Loss of Giant Kelp, Macrocystis pyrifera, Driven by Marine Heatwaves and Exacerbated by Poor Water Clarity in New Zealand

The legacies of land clearance and trophic downgrading accumulate to affect structure and function of kelp forests

Contact Info

Product

Resources

About