Estimating nitrogen loading and far-field dispersal potential from background sources and coastal finfish aquaculture: A simple framework and case study in Atlantic Canada

McIver, Reba; Milewski, Inka; Loucks, Ronald H.; Smith, Ruth E.

doi:10.1016/j.ecss.2018.01.005

Cited by 19 publications

(18 citation statements)

References 68 publications

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“…S1 and S2). Briefly, the NLM estimates watershed and atmospheric derived total dissolved nitrogen loads from several point (i.e., direct atmospheric deposition, wastewater discharge, seafood processing plants, finfish aquaculture) and non-point sources (i.e., indirect atmospheric deposition, septic systems, and fertilizer addition) with appropriate loss parameters (Valiela et al 1997, McIver et al 2015, McIver et al 2018. Final nitrogen loading rates were calculated by summing across all sources and standardized to the area of each bay (kg N ha bay -1 yr -1 ) to account for dilution effects.…”

Section: Data Collectionmentioning

confidence: 99%

A human impact metric for coastal ecosystems with application to seagrass beds in Atlantic Canada

Murphy

Wong

Lotze

2018

Preprint

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Coastal biogenic habitats are particularly vulnerable to cumulative human impacts from both terrestrial and marine realms. Yet the broad spatial scale used in current global or regional approaches of quantifying multiple anthropogenic stressors are not relevant to the local or baywide scales affecting most coastal biogenic habitats. To fill this gap, we developed a standardized human impact metric to quantify the magnitude of anthropogenic impacts to coastal ecosystems more broadly, and biogenic habitats in particular. We applied this metric to 180 seagrass beds (Zostera marina), an important biogenic habitat prioritized for marine protection, across Atlantic Canada. Our impact metric includes five bay-scale and four local-scale terrestrial and marine-based impacts. Results show that seagrass beds and coastal bays in Atlantic Canada exist across a wide gradient of human impacts. Considerable differences in the range and intensity of impacts within and between regions provide insight into where coastal bays and seagrass ecosystems are expected to be most and least affected by individual or cumulative human threats. We discuss implications for management and conservation planning, and the general application of our impact metric to other coastal regions and habitats in Canada and beyond.

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Section: Data Collectionmentioning

confidence: 99%

A human impact metric for coastal ecosystems with application to seagrass beds in Atlantic Canada

Murphy

Wong

Lotze

2018

Preprint

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“…The current fish farm lease (43°54'54.11" N; -64°48'43.62" W) near Spectacle Island (Fig. 1) occupies an area of 8 hectares (ha) and the sea cages occupy ~0.58 ha of the lease area (McIver et al, 2018). The fish farm was initially stocked with rainbow trout (Oncorhynchus mykiss) until ~2000, followed by Atlantic salmon (Salmo salar) until 2009, fallowed from 2010-2012, stocked with rainbow trout in 2012-2014.…”

Section: Study Areamentioning

confidence: 99%

“…The farm lease has been re-licensed for Atlantic salmon and rainbow trout from March 2015 to March 2020 (NSDFA, 2017). Information on production at the farm site is deemed proprietary, however it has been estimated at 760 mt annually for 2012-2014, with an estimated 30 mt of dissolved inorganic nitrogen being released from the farm every year (McIver et al, 2018). Environmental monitoring at the fish farm indicated that in 2014, one year prior to our sampling, mean sediment sulphides, an indicator or organic enrichment, were 4000 µM (NSDFA 2014).…”

Section: Study Areamentioning

confidence: 99%

“…Finfish aquaculture operations are known to discharge significant quantities of nutrient and organic waste to the surrounding environment. When in operation, the Port Mouton Bay fish farm increased the annual total dissolved nitrogen load from human sources to the entire bay by 14% or 30,400 kg (McIver et al, 2018), with the fish farm being the single largest contributor of dissolved nitrogen to the bay after atmospheric deposition. The release of particulate organic waste from fish farms can be significantly larger (10s-100s mt)…”

Section: Linking the Environment/eelgrass Structure To Infauna Communmentioning

confidence: 99%

“…not statistically significant, we observed higher mean microphytobenthos chlorophyll-a concentrations at sites within Port Mouton Bay compared to the reference PJ and other NS sites, in line with expected patterns from the published literature(Table 1). The enhanced microphytobenthos productivity in Port Mouton Bay may be a result of the overall higher nutrient loading from greater human development in the watershed and the finfish farm in the bay(McIver et al, 2018) compared to the more protected and less developed watershed in Port Joli Bay with much lower nutrient loading(Nagel et al, 2018). Under enhanced nutrient loading,…”

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confidence: 99%

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Peer Review #2 of "Potential impacts of finfish aquaculture on eelgrass (Zostera marina) beds and possible monitoring metrics for management: a case study in Atlantic Canada (v0.1)"

2018

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Eelgrass (Zostera marina) has been designated an Ecologically Significant Species in Atlantic Canada. The development and rapid expansion of netpen finfish aquaculture into sensitive coastal habitats has raised concerns about the impacts of finfish aquaculture on eelgrass habitats. To date, no studies have been done in Atlantic Canada to examine these impacts or to identify potential monitoring variables that would aid in the development of specific conservation and management objectives. As a first step in addressing this gap, we examined differences in environmental variables, eelgrass bed structure and macroinfauna communities at increasing distances from a finfish farm in Port Mouton Bay, a reference site in adjacent Port Joli Bay, and published survey results from other sites without finfish farms along the Atlantic Coast of Nova Scotia. Drawing on research done elsewhere and our results, we then identified possible metrics for assessing and monitoring local impacts of finfish aquaculture on eelgrass habitats. Our results suggest some nutrient and organic enrichment, higher epiphyte loads, lower eelgrass cover and biomass, and lower macroinfauna biomass closer to the farm. Moreover, community structure significantly differed between sites with some species increasing and others decreasing closer to the farm. Changes in the macroinfauna community could be linked to observed differences in environmental and eelgrass bed variables. These results provide new insights into the potential impacts of finfish aquaculture on eelgrass habitats in Atlantic Canada. We recommend a suite of measures for assessment and monitoring that take into account response time to disturbance and account for different levels of eelgrass organizational response (from physiological to community).

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Measuring and modeling nitrogen export from cranberry farms

Kennedy

Hoekstra

2021

Ecosphere

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Nitrogen (N) pollution is arguably the single greatest threat to coastal water quality in the United States. In the state of Massachusetts, sustainable management of cranberry agriculture requires detailed understanding of potential sources and losses of N, which can contribute to impaired coastal waters. Given the complexity of N transport processes, models are often used to quantify the amount of N delivered from cranberry farms to coastal waters. However, ambiguities in model parameters, inconsistencies in deriving N loading rates, and inaccuracies in spatial coverages leave open questions about the contribution of cranberry agriculture to impaired coastal waters. In this study, we synthesize the methods, assumptions, and results of all N budget studies conducted in cranberry farms from 1995 to 2019. We propose a new analytical framework for measuring N fertilizer export from cranberry farms which includes our best understanding of N retention and transport in cranberry farms. We then apply our results to two watershed land-use models (Massachusetts Estuaries Project Linked Watershed-Embayment Model, LM; the Waquoit Bay Nitrogen Loading Model, NLM) to quantify N loads contributed by cranberry farms to the highly eutrophic Wareham River estuary. We find that the LM and NLM are in close agreement with respect to the amount of N delivered from cranberry farms to the Wareham River estuary. In our application of the LM, we estimated that 7791 kg NÁyr −1 from cranberry farms, or 15% of the total N load, reached the estuary. By comparison, we found that the NLM estimated slightly higher N loads contributed by cranberry farms to the estuary: 8365 kg NÁyr −1 , or 16% of the total N load. However, the models gave contrasting estimates of unattenuated N loads from cranberry farms (9670 kg NÁyr −1 , LM; 12,870 kg NÁyr −1 , NLM) and the amount of N transmitted through the watershed to the estuary (81% LM; 65% NLM).

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Estimating nitrogen loading and far-field dispersal potential from background sources and coastal finfish aquaculture: A simple framework and case study in Atlantic Canada

Cited by 19 publications

References 68 publications

A human impact metric for coastal ecosystems with application to seagrass beds in Atlantic Canada

A human impact metric for coastal ecosystems with application to seagrass beds in Atlantic Canada

Peer Review #2 of "Potential impacts of finfish aquaculture on eelgrass (Zostera marina) beds and possible monitoring metrics for management: a case study in Atlantic Canada (v0.1)"

Measuring and modeling nitrogen export from cranberry farms

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