PSTs showed highest concentrations in early summer, consistent with phytoplankton bloom timings. The highest DA concentrations were measured along the east coast of Scotland and in Orkney. Whole fish concentrations were highest in pelagic species including Atlantic mackerel and herring, key forage fish for marine predators including seals, cetaceans and seabirds. Overall, fish had higher concentrations of DA compared to PSTs, with a peak in the summer / autumn months. For the first time, the concentrations of two toxin groups of commercial and environmental importance, domoic acid (DA) and saxitoxin (including Paralytic Shellfish Toxin (PST) analogues), were measured in the viscera of 40 different fish species caught in Scotland between February and November, 2012 to 2019. There is therefore a need for an improved understanding of the trophic transfer, and persistence of toxins in marine food webs. As well as their potential impacts on human health, toxin exposure from harmful algal blooms (HABs) has resulted in widespread morbidity and mortality in marine life, including top marine predators.

Harmful algal bloom events are increasing in a number of water bodies around the world with significant economic impacts on the aquaculture, fishing and tourism industries. The severe decline of the Arctic Skua colony at Slettnes fits reported trends for this species across most of its European breeding range, as well as for its important host species, the Arctic Tern Sterna paradisaea and the Black-legged Kittiwake Rissa tridactyla. The reproductive output in recent years is far too low to sustain a stable population. We provide evidence of both bottom-up (food shortage) and top-down (predation) effects on reproductive investment and hatching success in this colony. The combined effects of food shortage and nest predation led to total breeding failures in 2017–2019. At the same time, nest predation by Red Foxes, the likely predator involved, increased during the six-year study. In addition, we developed a demographic model to estimate the fecundity required for a stable population.Ī higher proportion of time spent at sea, small eggs, low adult female body mass and indirect assessment of foraging fish availability suggested food shortages in four of six recent study years. We deployed nest cameras to identify predators in 2018–2019. We compared nest counts between 1997–19–2019 and collected data on egg size, clutch size and nest success for all years, and adult body mass, nest attendance, at-sea activity, aggressive nest defence, Red Fox Vulpes vulpes encounters, daily nest survival and adult survival for 2014–2019.

To document the decline of Europe’s largest Arctic Skua colony and quantify bottom-up and top-down effects on reproduction. The number of breeding pairs of Europe’s largest Arctic Skua Stercorarius parasiticus colony at Slettnes, Norway, showed a dramatic decline of at least 50% over two decades, with food shortage in four years and increasing predation by Red Fox Vulpes vulpes leading to total breeding failure in five out of six recent study years. Overall, our results point to the importance of regional studies of prey fields, and caution against inferring ecological consequences based only on large-scale trends in key taxa or mean community traits. Further, the estimated average prey community body size has increased in several of the locations considered. This decrease was accompanied by declining abundances of small copepods, and shifts in the timing of peak annual prey abundances. In the western North Sea, the estimated amount of available energy in the prey field has decreased by more than 50% since the 1960s. We found marked spatial variation in the prey field, with Calanus copepods generally being much more common in the northern part of the study area. Here, we use 60 + years of Continuous Plankton Recorder data to explore temporal trends in key taxa and community traits in the prey field of planktivorous lesser sandeels (Ammodytes marinus) in the North Sea, the Faroes and southern Iceland. This may lead to shifts in the prey fields of planktivorous fish, which play a key role in transferring energy up marine food chains. The phenology, distribution, and size composition of plankton communities are changing rapidly in response to warming.

Puffin size