We are making the fish in our oceans handicapped...

Fish are losing their sense of smell as rising carbon emissions turn the water they live in, to acid.

A study in 2018 July has revealed that as levels of carbonic acid in seawater rise, sea bass lose up to half their smelling capacity. Surges in atmospheric carbon dioxide increase ocean acidity as the gas dissolves in water. 

The findings are significant as these fish rely on smell to do everything from finding food and potential mates to detecting predators in their vicinity.

The scientists compared the behaviour of young sea bass at current carbon dioxide levels to the levels expected at the end of the century, when oceans are predicted to contain up to two and a half times the levels of the gas seen today.They noticed big changes in the behaviour of the fish inhabiting the most acidic water. Not only did the bass swim less, they appeared not to notice the presence of predators.

Previous research has indicated that besides directly affecting fish noses, carbon dioxide harms fish nervous systems and disrupts the processing of information in their brains.

Having to cope with two different problems caused by carbon dioxide, rather than just one, may reduce the ability of fish to adapt.

Other studies have suggested that as seawater becomes more acidic, it will erode the hearing ability of fish and make them unable to hear approaching predators.

Birds & Ecosystem Services

Attribution: Andrew Butko / CC-BY-SA 3.0

Everyone in the world depends completely on Earth’s ecosystems and the services they provide, such as food, water, disease management, climate regulation, spiritual fulfillment, and aesthetic enjoyment. 

Studies have sought to examine the services provided by birds in the ecosystems they inhabit.

Birds encourage more and healthier plant growth by the spread of their poop which is an excellent additive to any fertilizer. By spreading activities through different habitats, birds can move nutrients from one place to another, which is particularly relevant in places where plant growth is limited by nutrient availability. A study on the islands in the Gulf of California showed that when birds roosted on them, the guano deposits they left behind provided nutrients to plants on the island. As a result, islands with seabirds had plants that grew taller and faster and were much more productive than those on islands without birds.

Utkarsh22december / CC-BY-SA 4.0

Wetlands are considered one of the most valuable habitats, providing an array of important services like shoreline stabilization and water filtration. In the southeastern United States, snails can overgraze the grasses in salt marshes and completely convert a productive marsh into mudflats. Several species of birds such as oystercatchers, curlews, and plovers are predators of these snails and control their numbers, which regulates primary productivity of salt marshes.

Waterbirds play key functional roles in many aquatic ecosystems, including as predators, herbivores and vectors of seeds, invertebrates and nutrients. Waterbirds can maintain the diversity of other organisms, control pests, be effective bio-indicators of ecological conditions, and act as sentinels of potential disease outbreaks. They also provide important provisioning (meat, feathers, eggs, etc.) and cultural services to both indigenous and westernized societies. 

Apple Blossom @ Manali, India / Sanu N / CC-BY-SA 4.0

The construction of nest boxes for great tits in apple orchards has been shown to lead to greater numbers of birds in the area, which forage on caterpillars that can cause damage to crops, resulting in significantly higher crop yields. Similarly, the use of artificial perches for raptors around agricultural fields may increase the number of raptors that prey on rodents that can cause damage to crops. If installed and maintained properly, the construction of bird nest boxes can eliminate the need for pesticides, saving farmers money and preventing potentially dangerous chemicals from being applied.

Buffalos and crane birds, Chinawal village, India / ABHIJEET / CC-BY-SA 3.0

Many birds perch on livestock like cattle and forage on insects that live on them. Cattle egrets are particularly well known for making a living this way. When infested with ticks, cows can become anemic and milk production flags. In Pakistan, birds are capable of effectively preying on these parasites, leading to healthier and more productive cows. This predation by birds is even more effective than pesticides in some cases.

Scavenging by birds is an important mechanism of waste disposal in many areas and prevents the outbreak of diseases than can occur through the accumulation of animal carcasses. In India, declines in vultures led to increases in feral dogs as there was less competition for carrion as a food source. The explosion of the dog population led to increases in rabies outbreaks and human injuries from dog attacks. The total estimated health cost of vulture declines between 1993 and 2006 is a whopping $34 billion.

KostasGiannakis / CC-BY-SA 4.0

Another way that birds can provide regulating services is through promoting forest growth. When birds pick a seed or fruit from a plant and fly off with it, they end up transporting the seed to another place where it can germinate. This behavior is a major mechanism for seed dispersal in many plants and can increase the genetic diversity of plants in a particular area by spreading seeds. By germinating the seeds of trees, birds can contribute to the reforesting of deforested lands, diminishing the costs of restoration. In oak forests in Sweden, the cost of replacing the seed dispersal services of Eurasian jays in oak regeneration is an estimated $9,400 per hectare

Finally, cultural services by birds include spiritual enrichment, companionship, music and the appreciation of nature.

Acknowledgement : The blog post above is largely an edited version of this article.