A preliminary model of iron fertilisation by baleen whales and Antarctic krill in the Southern Ocean: Sensitivity of primary productivity estimates to parameter uncertainty

Ratnarajah, Lavenia; Melbourne-Thomas, Jess; Marzloff, Martin P.; Lannuzel, Delphine; Meiners, Klaus M.; Chever, Fanny; Nicol, Stephen; Bowie, Andrew R.

doi:10.1016/j.ecolmodel.2015.10.007

Cited by 41 publications

(55 citation statements)

References 86 publications

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“…In the Southern Hemisphere, baleen whales depend primarily on krill (Euphausia superba, Euphausiidae), a key species of the Southern Ocean food chain (Trivelpiece et al, 2011) as their main prey source (Laws, 1977;Ratnarajah et al, 2016). The availability of krill is closely linked to primary productivity that determines the distribution and phenology of many marine predators (Ainley et al, 1998;van Franeker et al, 2002;Thiele et al, 2004).…”

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Ecosystem modelling to quantify the impact of historical whaling on Southern Hemisphere baleen whales

et al. 2017

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Many baleen whales were commercially harvested during the 20th century almost to extinction. Reliable assessments of how this mass depletion impacted whale populations, and projections of their recovery, are crucial but there are uncertainties regarding the status of Southern Hemisphere whale populations. We developed a SouthernHemisphere spatial "Model of Intermediate Complexity for Ecosystem Assessments" (MICE) for phytoplankton, krill (Euphausia superba) and five baleen whale species, to estimate whale population trajectories from 1890 to present. To forward project to 2100, we couple the predator-prey model to a global climate model. We used the most up to date catch records, fitted to survey data and accounted for key uncertainties. We predict Antarctic blue (Balaenoptera musculus intermedia), fin (Balaenoptera physalus) and southern right (Eubalaena australis) whales will be at less than half their pre-exploitation numbers (K) even given 100 years of future protection from whaling, because of slow growth rates. Some species have benefited greatly from cessation of harvesting, particularly humpbacks (Megaptera novaeangliae), currently at 32% of K, with full recovery predicted by 2050. We highlight spatial differences in the recovery of whale species between oceanic areas, with current estimates of Atlantic/Indian area blue (1,890, <1% of K) and fin (16,950, <4% of K) whales suggesting slower recovery from harvesting, whilst Pacific southern right numbers are <7% of K (2,680).Antarctic minke (Balaenoptera bonaerensis) population trajectories track future expected increases in primary productivity. Population estimates and plausible future predicted trajectories for Southern Hemisphere baleen whales are key requirements for management and conservation. K E Y W O R D SAntarctic, baleen whale, commercial whaling, ecosystem model, krill, multispecies model

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Ecosystem modelling to quantify the impact of historical whaling on Southern Hemisphere baleen whales

et al. 2017

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“…Calculations have suggested that pre‐exploitation populations of blue whales ( Baleoptera musculus ) could have resulted in a contribution to primary productivity of 23.4 g C m −2 yr −1 , when all parameter estimates are at their upper limits, including the Fe concentration in krill (190 mg kg −1 , in Kim et al ), but only 1.5 × 10 −4 g C m −2 yr −1 when all parameter estimates are at their lower limits, including the Fe concentration in krill (4 mg kg −1 , from this study) (Ratnarajah et al ). In this preliminary model, the variability of Fe concentration in krill was consistently the most influential parameter determining the potential of blue, fin ( B. physalus ) and humpback ( Megaptera novaeangliae ) whales to affect productivity in the Southern Ocean.…”

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confidence: 65%

“…Biological recycling of Fe by higher order marine animals in the Southern Ocean is a relatively new field but is receiving considerable attention (Smetacek and Nicol 2005;Tovar-Sanchez et al 2007;Tovar-Sanchez et al 2009;Nicol et al 2010;Schmidt et al 2011;Smith et al 2013;Ratnarajah et al 2014;Wing et al 2014;Ratnarajah et al 2016). The wide range of Fe concentrations in whole krill (4-190 mg kg 21 ) is the most influential parameter in determining the recycling efficiency of blue, fin and humpback whales on primary productivity in the Southern Ocean (Ratnarajah et al 2016).…”

Section: Implications For the Transfer Of Iron To Higher Trophic Levelsmentioning

confidence: 99%

Understanding the variability in the iron concentration of Antarctic krill

et al. 2016

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Antarctic krill may play a significant role in the Southern Ocean iron cycle. However, understanding the control on iron budgets by Antarctic krill is hampered by the large range in the reported iron concentration of krill. The aim of this study was to investigate the causes of the large range of iron concentrations in krill reported in the literature (6-190 mg kg 21 ). Antarctic krill samples were collected from three research voyages to Pyrdz Bay, Antarctica, and analysed individually. Iron concentrations were measured using sector field inductively coupled plasma mass spectrometry in whole krill specimens and in the isolated stomach, digestive gland, muscle, body (whole krill excluding stomach and digestive gland), exoskeleton and faecal pellets. Iron concentrations in stomach (6-98 mg/kg), digestive gland (14-82 mg kg 21 ), and faecal pellet (683-1039 mg kg 21 ) were higher compared to muscle (4-7 mg kg 21 ), exoskeleton (6-15 mg kg 21 ), and body (4-18 mg kg 21 ) indicating that krill may ingest more iron than they require for physiological processes. Iron concentrations in whole krill from March 2012 (10 6 3 mg kg 21 ) were significantly lower compared to February 2003 (19 6 7 mg kg 21 ) and February 2015 (18 6 12 mg kg 21 ). Overall, the iron concentrations in krill from this study were consistently at the lower end of the published range. We propose that the large range in reported whole iron concentrations of krill can be accounted for by a combination of seasonal and regional differences in sampling, reflecting differences in the quantity and quality of their diet.

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“…First, we estimated consumption C of krill (tonnes) per whale per year from the literature, using estimates of Ratnarajah et al (2016) for blue, fin and humpback whales. For minke whales we calculated consumption by scaling up estimates of consumption derived for minke whales in the Ross Sea, Areas III and VI (Tamura & Konishi 2006 and Areas IV and V (Tamura et al 1997).…”

Section: Prey Dynamics (Krill and Copepods)mentioning

confidence: 99%

“…Hemisphere, baleen whales depend primarily on krill (Euphausia superba, Euphausiidae), a key species of the Southern Ocean food chain (Trivelpiece et al 2011) as their main prey source (Laws 1977;Ratnarajah et al 2016). The availability of krill is closely linked to primary productivity that determines the distribution and phenology of many marine predators (Ainley et al 1998;Thiele et al 2004;van Franeker et al 2002) (Ainley et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Managing direct and indirect threats to marine ecosystems to balance multiple objectives

Tulloch¹

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Human activities affecting the environment are intensifying. In marine ecosystems, direct stressors of overfishing and habitat destruction have led to biodiversity declines, prompting calls for conservation action and more sustainable resource management. Managing stressors becomes more challenging when stressors interact, or are indirect, whereby the source of the threatening activity is displaced from impacts, such as the localised effects of global warming, or runoff from land-use change degrading coral reefs. Effective management requires improved understanding of ecosystem responses to multiple stressors and consideration of interactions between stressors and species.Opposing objectives and outcomes of marine conservation (i.e. reducing stressors) versus resource management (often increasing stressors) compromise effective decision-making. Approaches are needed that include ecological and socio-economic information to promote long-term sustainability of extractive uses, protect functioning ecosystems, and conserve biodiversity. The choice of tool used to inform ecosystem management is typically constrained by management goals and available resources -spatial planning is typically used for conservation, whereas resource management relies more on population modelling.The goal of this thesis is to harness spatial and population modelling techniques to combine resource management with biodiversity conservation and link direct and indirect stressors to marine biodiversity persistence. Chapter 1 provides the context for the thesis, where I explore these themes and outline differences in decision-making for conservation versus extraction. In Chapter 2, I explore how agencies have managed stressors to date, and show that a decision-theoretic approach known as "structured decision-making" (SDM) is a more logical and effective way of managing stressors than traditional approaches that map threats. SDM requires clear objectives, canvassing of alternative management options, and linking outcomes for biodiversity to the effectiveness of each management option. SDM ensures that conservation actions occur where they are the most cost-efficient or effective. I apply recommendations from Chapter 2 in two case studies for managing multiple stressors to marine ecosystems: 1) spatial planning for oil palm agriculture and coral reef fisheries in Papua New Guinea (Chapters 3 and 4), and 2) managing whale species affected by harvesting, climate change and krill population dynamics in the Southern Hemisphere (Chapters 5 and 6).In Chapter 3 I combine ecosystem models and threat maps with spatial conservation planning to predict responses of coral and seagrass ecosystems to changing land uses. My novel framework identifies high priority areas for marine reserves whilst accounting for indirect impacts of land use change such as oil palm development and uncertainty in future stressor intensities. I demonstrate ii how we can reduce adverse impacts of oil palm expansion and make more effective whole-ofsystem decisions for coasta...

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A preliminary model of iron fertilisation by baleen whales and Antarctic krill in the Southern Ocean: Sensitivity of primary productivity estimates to parameter uncertainty

Cited by 41 publications

References 86 publications

Ecosystem modelling to quantify the impact of historical whaling on Southern Hemisphere baleen whales

Ecosystem modelling to quantify the impact of historical whaling on Southern Hemisphere baleen whales

Understanding the variability in the iron concentration of Antarctic krill

Managing direct and indirect threats to marine ecosystems to balance multiple objectives

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