Prey or predator—expanding the food web role of sandeel Ammodytes marinus

Eigaard, Ole Ritzau; Deurs, Mikael van; Behrens, Jane; Bekkevold, Dorte; Brander, Keith; Plambech, Marie; Plet-Hansen, Kristian Schreiber; Mosegaard, Henrik

doi:10.3354/meps11064

Cited by 19 publications

(6 citation statements)

References 39 publications

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“…However, density dependence is likely limited to the egg and larval stages, while only post-metamorphic sandeels are modeled. Cannibalism on post-metamorphic individuals is low (Ritzau Eigaard et al, 2014) and growth suppression of small fish by larger individuals is unlikely since sandeels usually aggregate according to size (Johnsen et al, 2009;Jensen et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

Exploring the Influence of Food and Temperature on North Sea Sandeels Using a New Dynamic Energy Budget Model

et al. 2018

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The zooplanktivorous schooling fish sandeels A. marinus comprise a quarter of North Sea fish biomass and are essential food for a number of marine mammals and birds. However, in recent decades there has been a decline in the abundance of older sandeels, with increased overwinter mortality proposed as a contributor. To survive winter animals require a minimum energy reserve which is determined by temperature, prey abundance, and possibly prey size. Here a new dynamic energy budget model is created to determine the influence of food and temperature on sandeel energy dynamics. The model hindcasts changes in energy and survival between 2000 and 2008, a period of pronounced stock decline in the northwestern North Sea. Overwinter starvation mortality was a large contributor toward a recent decline in sandeels in northern UK waters. Highest overwinter mortality rates were recorded for juveniles and not individuals aged 1 or over due to the effect of weight-specific metabolism. However, a sensitivity analysis of the model suggests that mortality rates are more sensitive to changes in copepod abundance in the build up to overwintering rather than temperature during overwintering. Further, projections show that temperature rises are negated by increases in large, but not small copepods. The conclusion is that food-driven size-selective starvation mortality contributed to the northwestern North Sea stock decline and that indirect food web effects of climate change are greater than direct physiological effects on sandeels.

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Section: Discussionmentioning

confidence: 99%

Exploring the Influence of Food and Temperature on North Sea Sandeels Using a New Dynamic Energy Budget Model

et al. 2018

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“…When Atlantic herring and mackerel are at low population levels, NWA Ammodytes can be released from predation, resulting in a competitive advantage, and vice versa (Polis, Myers, & Holt, 1989). Further, intercohort cannibalism (adult Ammodytes consuming larvae) can occur in regions and years with low abundances of alternative prey (Eigaard et al, 2014, North Sea). Because generalist predators typically consume the most abundant prey available, out of phase cycles of NWA Ammodytes with other forage fishes in the region could have important trophic effects on higher‐level predators.…”

Section: Life Historymentioning

confidence: 99%

The role of sand lances (Ammodytes sp.) in the Northwest Atlantic Ecosystem: A synthesis of current knowledge with implications for conservation and management

et al. 2020

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The American sand lance (Ammodytes americanus, Ammodytidae) and the Northern sand lance (A. dubius, Ammodytidae) are small forage fishes that play an important functional role in the Northwest Atlantic Ocean (NWA). The NWA is a highly dynamic ecosystem currently facing increased risks from climate change, fishing and energy development. We need a better understanding of the biology, population dynamics | 523 STAUDINGER ET Al.

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“…More significantly, environmental conditions for sandeels appear to be worsening, with sea temperature increases and oceanographic changes affecting their physiology, food supply, phenology and survival, leading to trophic mismatch and less food for seabirds (Carroll et al, 2015;Frederiksen et al, 2006;Régnier et al, 2017). The recent discovery that sandeels are cannibalistic, with such behaviour possibly driven by low prey availability or late hatching of larvae, may further explain low recruitment in some years (Eigaard et al, 2014).…”

Section: F I G U R Ementioning

confidence: 99%

Combined bottom‐up and top‐down pressures drive catastrophic population declines of Arctic skuas in Scotland

Perkins

Ratcliffe

Suddaby³

et al. 2018

Journal of Animal Ecology

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Understanding drivers of population change is critical for effective species conservation. In the northeast Atlantic Ocean, recent changes amongst seabird communities are linked to human and climate change impacts on food webs. Many species have declined severely, with food shortages, and increased predation reducing productivity. Arctic skua Stercorarius parasiticus, a kleptoparasite of other seabirds, is one such species. The aim of the study was to determine relative effects of bottom-up and top-down pressures on Arctic skuas across multiple colonies in a rapidly declining national population. Long-term monitoring data were used to quantify changes in population size and productivity of Arctic skuas, their hosts (black-legged kittiwake Rissa tridactyla, common guillemot Uria aalge, Atlantic puffin Fratercula arctica, Arctic tern Sterna paradisaea) and an apex predator (great skua Stercorarius skua) over 24 years (1992-2015) in Scotland. We used digital mapping and statistical models to determine relative effects of bottom-up (host productivity) and top-down (great skua density) pressures on Arctic skuas across 33 colonies, and assess variation between three colony types classified by host abundance. Arctic skuas declined by 81% and their hosts by 42%-92%, whereas at most colonies great skuas increased. Annual productivity declined in Arctic skuas and their hosts, and reduced Arctic skua breeding success was a driver of the species' population decline. Arctic skua productivity was positively associated with annual breeding success of hosts and negatively with great skua density. Intercolony variation suggested Arctic skua trends and productivity were most sensitive to top-down pressures at smaller colonies of host species where great skuas had increased most, whereas bottom-up pressures dominated at large colonies of host species. Scotland's Arctic skua population is declining rapidly, with bottom-up and top-down pressures simultaneously reducing breeding success to unsustainably low levels. Marine food web alterations, strongly influenced by fisheries management and climate change, are driving the decline, and this study demonstrates severe vulnerability of seabirds to rapid change in human-modified ecosystems. Potential but untested conservation solutions for Arctic skuas include marine protected areas, supplementary feeding within colonies and management of great skuas.

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Prey or predator—expanding the food web role of sandeel Ammodytes marinus

Cited by 19 publications

References 39 publications

Exploring the Influence of Food and Temperature on North Sea Sandeels Using a New Dynamic Energy Budget Model

Exploring the Influence of Food and Temperature on North Sea Sandeels Using a New Dynamic Energy Budget Model

The role of sand lances (Ammodytes sp.) in the Northwest Atlantic Ecosystem: A synthesis of current knowledge with implications for conservation and management

Combined bottom‐up and top‐down pressures drive catastrophic population declines of Arctic skuas in Scotland

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