Edexcel GCSE Biology - 9.4 Human Influences on the Environment - 9.4.1 Human Impact on Biodiversity

Sep 5, 2026

Revision notes for Edexcel GCSE Biology Unit 9.4 Human Influences on the Environment, focusing on human impact on biodiversity. Covers fish farming as a method to reduce pressure from overfishing, including breeding, monitoring, diet control, and disease prevention, and the potential biodiversity risks such as predator attraction, rapid disease spread, escaped caged fish, and eutrophication. Also explains how introducing non-indigenous species harms native biodiversity through competition, food-chain disruption, and disease, and details how eutrophication from fertilizer runoff reduces oxygen and aquatic survival.

LanguageEnglish

CategoryExam

FormatPDF

Pages13

Reading Time33 min

AccessFree to download

9.4.1 Human Impact on Biodiversity

Fish Farming

The effect of fish farms on biodiversity

Non-Indigenous Species

Competition

Impacts on the food chain

Disease

Eutrophication

9.4.2 Assessing Pollution

Head to www.savemyexams. com for more awesome resources Edexcel GCSE Biology 9 .4 Human In}uenceson the Environment Contents 9.4.1 Human Impact on Biodiversity 9.4.2 Assessing Pollution 9.4.3 Bene|ts of Maintaining Biodiversity Page 1 of 13 © 2015 − 2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers Your notes Head to www.savemyexams. com for more awesome resources 9.4.1 Human Impact on Biodiversity Fish Farming Bene|ts of |sh farming Most |sh are still caught in the wild (i. e. in the open ocean or in freshwater rivers and lakes) However, over|shing has lead to dramatic declines in many |sh populations Fish farms are ways of raising large numbers of |sh in a small space to provide food (protein) for humans Fish are bred in large tanks or cages to minimise energy losses and maximise yield Methods to maximise yield in |sh farms Within |sh farms, large numbers of |sh are kept in freshwater or seawater enclosures and are carefully monitored and controlled in diyerent ways (many of which are not possible with wild-caught |sh) Selective breeding ensures high quality, fast-growing |sh Interspeci|c predation is prevented using nets and cages Intraspeci|c predation is limited by grouping |sh according to their age and size Water quality is carefully controlled by monitoring pH and temperature as well as removing |sh waste or dead |sh Diet is controlled by feeding high protein |sh pellets regularly to ensure rapid growth Diseases and pests are prevented using antibiotics and pesticides or biological controls Theeyectof |sh farmson biodiversity Fish farms, whilst reducing the pressure of over|shing of wild |sh, can have a negative impact on biodiversity in several ways Predators may be attracted to the |sh farms and may get caught in nets trying to reach the |sh Diseases can spread quickly in |sh farms duetothe enclosed space and number of individuals inclose proximity. Diseases can also spread in the water to other species outside of the |sh farm If any caged |sh were to escape, they can cause issues with the native species nearby (i. e. those that live in the area naturally) Eutrophication can occur Fish Farming Methods Table Page 2 of 13 © 2015 − 2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers Your notes Head to www.savemyexams. com for more awesome resources Page 3 of 13 © 2015 − 2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers Your notes Head to www.savemyexams. com for more awesome resources Non-Indigenous Species An indigenous species is one which is native to a particular area Introducing a non-indigenous species into an area can have negative ayects on the native species Introduction may be purposeful (for example, as a biological control) or it might be accidental (for example, if an organism escapes captivity) Negative eyects occur due to competition, impactson the food chain and disease This results in a decrease in the biodiversity of the habitat Competition The non-indigenous species may compete with native species for food, water or space This could result in one or more indigenous species being outcompeted and possibly being eradicated For example, the red squirrel is a native species of squirrel in the UK that has declined in numbers drastically due to the introduction of the North American grey squirrel The grey squirrel not only carry the deadly parapox virus, which is fatal to red squirrels, but they also directly compete with red squirrels for food and nesting sites Impactson the food chain A new species in the food chain would disrupt the balance as it would provide a new food source or anew predator This would impact the populations ofthe other organisms in the food web For example, the Canetoad is a species of poisonous toad that was introduced into Australia as a biological control to help combat an infest

FAQs

How does fish farming reduce pressure on biodiversity compared with overfishing?

Fish farms raise large numbers of fish in controlled spaces, providing food while reducing the need to catch many fish in the wild.

What negative effects can fish farming have on biodiversity?

Fish farms can attract predators, enable rapid disease spread due to enclosure, cause problems if caged fish escape, and contribute to eutrophication.

How do non-indigenous species introductions reduce biodiversity?

They can compete with native species for resources, disrupt food-chain balance, and introduce new diseases that may devastate indigenous populations.

Sep 5, 2026

Upload by Valentina