Publications by authors named "Joanna L Kershaw"

Article Synopsis
  • Harmful algal blooms (HABs) can release toxins that are eaten by fish, which may then harm marine animals like harbour seals.
  • Studies show that some seal populations in Scotland have been decreasing, and tests suggest they might be getting sick from these toxins in their food.
  • A model was used to see how many seals could be affected by toxins, showing that a small percentage of both young and adult seals might ingest dangerous levels of one specific toxin, called domoic acid, which could be causing their decline.
View Article and Find Full Text PDF

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. 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. There is therefore a need for an improved understanding of the trophic transfer, and persistence of toxins in marine food webs.

View Article and Find Full Text PDF
Article Synopsis
  • Climate change is causing significant shifts in the oceans, impacting marine ecosystems and top predator species like humpback whales in the Gulf of St. Lawrence, Canada.
  • A study tracking female humpback whales over 15 years found variations in pregnancy rates, but a notable decline in calving rates, linked to environmental factors such as prey availability.
  • Findings indicate that poor prey conditions may hinder reproductive success not due to an inability to get pregnant, but because whales struggle to accumulate necessary energy for pregnancy and nursing.
View Article and Find Full Text PDF

The fate and transportation of mercury in the marine environment are driven by a combination of anthropogenic atmospheric and aquatic sources, as well as natural geological inputs. Mercury biomagnifies up the food chain, resulting in the bioaccumulation of toxic concentrations in higher trophic organisms even when concentrations in their habitat remain below the threshold level for direct toxicity. As a result, mercury exposure has been recognised as a health concern for both humans and top marine predators, including cetaceans.

View Article and Find Full Text PDF

Mammalian adipose tissue is increasingly being recognized as an endocrine organ involved in the regulation of a number of metabolic processes and pathways. It responds to signals from different hormone systems and the central nervous system, and expresses a variety of protein factors with important paracrine and endocrine functions. This study presents a first step towards the systematic analysis of the protein content of cetacean adipose tissue, the blubber, in order to investigate the kinds of proteins present and their relative abundance.

View Article and Find Full Text PDF

Since 2000 there has been a major decline in the abundance of Scottish harbour seals Phoca vitulina. The causes of the decline remain uncertain. The aim of this study was to establish the extent to which the seals in the regions of greatest decline have been exposed to Brucella, a bacterial pathogen that causes reproductive failure in terrestrial mammalian hosts.

View Article and Find Full Text PDF

Mammalian body condition is an important individual fitness metric as it affects both survival and reproductive success. The ability to accurately measure condition has key implications for predicting individual and population health, and therefore monitoring the population-level effects of changing environments. No consensus currently exists on the best measure to quantitatively estimate body condition in many species, including cetaceans.

View Article and Find Full Text PDF

Cortisol is one of the main glucocorticoid hormones involved in both the mammalian stress response, and in fat metabolism and energy regulation, making it of increasing interest as a biomarker for stress, health and overall physiological state. However, transient stress responses to animal handling and sampling may be important sources of measurement artefact when investigating circulating concentrations of this hormone in wildlife. Here, cortisol concentrations were measured in the plasma and, for the first time, in the blubber of live captured adult harbour seals (Phoca vitulina).

View Article and Find Full Text PDF