The already endangered African penguins are in deep distress by finding themselves in a "climate trap" that is threatening habitats and loss of staple food like sardines and anchovies.
The birds' burden of climate change was borne by a new research that highlighted how overfishing off Africa's southern tip is exacerbating the existential crisis of African penguins.
Penguins are seeking prey-rich sea front where sardines and anchovies are aplenty, but when they reach the coastal hotspots of Namibia and South Africa, the food is no longer there.
"These were once reliable cues for prey-rich waters, but climate change and industrial fishing have depleted forage fish stocks in this system," noted the authors.
Climate trap is most apparent in the coasts of Namibia and South Africa where the local penguin populations have already lessened by 50 percent with survival chances looking grim.
Chasing signs of edible fish, low ocean temperatures and fragrant planktons, the young penguins swim thousands of miles away from their place of origin.
On arrival what they find is less edible gobies and jellyfish, which are very short on calories.
This "ecological trap" of settling in degraded habitats blemished by environmental changes is described in the study published in Current Biology.
Led by ecologist Richard Sherley of Exeter University, the study followed satellite tracking of 54 young penguins from the breeding ranges in Namibia and South Africa and monitored them as they dispersed westward and northward.
Endangered Species
Already declared endangered, the population of African penguins has entered crisis levels. Found on the southern tip, African penguins (Spheniscus demersus) are shorter than their polar peers with a height less than 28 inches and with a lower weight.
"Juvenile African penguins look for areas of low sea temperatures and high chlorophyll-a, which indicates the presence of plankton and therefore the fish which feed on it," added Sherley.
Adverse conditions are increasing further and threatening their survival. Such conditions include changing sea temperature, salinity and acidity of the seawater, which is driving their favorite fish far away.
With the preferred diet of sardines and anchovies drifting to the distant east, the penguin colonies are struggling to survive and breeding conditions are also in jeopardy.
Fishing Curbs Required
Expressing concern over the falling numbers of African penguins, the researchers said it is unclear whether they can adapt to the changes.
The study noted the present conditions are escalating the problem and suggested immediate steps like curbs in fishing.
"Our results support suspending fishing when prey biomass drops below certain levels, and suggest that mitigating marine ecological traps will require major conservation action," Sherley added.
Mercury Threat To Oceans
Meanwhile, fears of rising levels of neurotoxic mercury in sea life are threatening the food supply chain.
The mercury levels will be augmented by the changing rainfall patterns that will push an average of 30 percent more water, filled with organic debris, into coastal areas by 2100.
The contamination will disrupt marine ecosystems and alter the equilibrium of microbes at the bottom of the food web, according to experiments.
Escalating methylmercury concentrations in zooplanktons will finally take the mercury to the human consumer who eats fish, according to a study in Science Advances.
Co-author Erik Björn, of Umeå University in Sweden, warned that the incoming mercury could poison the food chain. Methylmercury has many fatal effects and causes birth defects and kidney damage.
