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Course: Middle school biology - NGSS > Unit 6
Lesson 2: Biodiversity and ecosystem healthBiodiversity and ecosystem health: a Hawaiian Islands case study
Biodiversity describes the variety of species found in Earth’s terrestrial and oceanic ecosystems. The completeness or integrity of an ecosystem’s biodiversity is often used as a measure of its health. Created by Khan Academy.
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- Why is she saying "Ha-v-aii" instead of Hawaii? It's confusing me.(15 votes)
- some Hawaiians also pronounce like this,
so it's not completely strange.
hope this helps.(36 votes)
- Would the Earth be better without humans at all?(13 votes)
- probably, humans have been the reasons of many species decline. Humans also take up way more space and resources than we need.
fact: every single person on the planet could fit in the small country of Belgium.(22 votes)
- Okay so what exactly is biodiversity in other places the Hawaii?(5 votes)
- Biodiversity is a measurement of the number of living species in a certain area.
In the Amazon Rainforest in South America, another biodiversity hotspot, the biodiversity includes around 2,500 animal species and about 80,000 plant species!(16 votes)
- Why does she pronounce "W" like "V"? Is there any real reason to this or is it just some weird accent related thing?(8 votes)
- It is just her accent.
Hope this helps!(4 votes)
- Since islands are 'hotspots' for biodiversity, what is the place that has the least biodiversity?(6 votes)
- The middle of Antarctica would be a satisfactory answer for that question, as it sees no plants and the only animals it sees would be wandering seabirds that got lost.(7 votes)
- Can someone please tell me how there are half a million islands in the world and it only takes up 5% of earth's land area, 20% of the world's plant species, and 15% of the world's mammal, bird, and amphibian species?(5 votes)
- Well, most islands are still pretty small. So, if continents are that much bigger, then they are likely to contain most of the world's flora and fauna, as well as its landmass. However, it's surprising how much diversity islands contain. Due to their isolation from the continents, much of the wildlife and plant life is unique. For example, Australia's flora and fauna is very different from the rest of the world's because it was isolated from other continents for so long. I hope this answers your question!(9 votes)
- she keeps saying havieii instead of Hawaii.(6 votes)
- It's just the accent. Nothing wrong about it.(2 votes)
- why was the palm tree 5 feet off the ground and sideways and almost falling down?(4 votes)
- The map at00:59showing the islands in red, excluding continents the largest island is Greenland (not in red) the second largest is New Guinea (in red) third largest is Borneo (not in red) and forth largest is Madagascar (in red) next is Baffin island (not in red). I don't understand the criteria used is the 5% the red area or the actual area of Islands.(4 votes)
- anyone else love the aloha at the end?(4 votes)
Video transcript
(waves splashing) - [Narrator] When you think of islands, you might think of pristine
beaches and palm trees gently swing along with a warm breeze. Sounds like paradise. And as a scientist, islands are my kind of place for research. Islands are very beautiful and they also have a lot of biodiversity. Biodiversity can be described as the variety of species in an ecosystem. Now, some ecosystems have
higher biodiversity than others, but all ecosystems have a variety of species that interact in specific ways with one another. Islands have such a variety of species that they're often called
biodiversity hotspots. They're home to so many diverse species, much more so than the continents. There are nearly half a million
islands around the world, but they only make up about
5% of the Earth's land area. Yet, islands are home to 20%
of the world's plant species and 15% of all mammal,
bird and amphibian species. Many of these island
species can only be found on one island or within
a group of islands. For example, you can only find the 'i'iwi, a honeycreeper bird species,
in the main Hawaiian islands in the North Pacific Ocean. (birds chirping) The 'i'iwi are important
pollinator species for Hawaiian plants, including the 'opelu and and the 'ohi'a. Pollination is an essential
part of plant reproduction allowing plants to produce
their fruits and seeds. While the 'i'iwi feeds on the
sweet nectar of these plants, this bird also helps to
support the next generation of 'opelu and 'ohi'a. These and other types of interactions are happening all the time between species in an ecosystem. You can think of biodiversity
as a sort of safety net, with each species as a knot, and the ropes between knots
as their interactions. The diversity of species
and their interactions, hold the net together allowing the ecosystem to function. Plus, the relationships between
species are often unique. For example, the 'i'iwi
has a special curved bill, and it's evolved to feed on the nectar of very specific flowers
that are similarly curved. Like the 'opelu. Now, even though the 'i'iwi is highly adapted to its
environment, if something happens to the 'opelu or 'ohi'a and
the plants start to decline, it can spell disaster for the 'i'iwi. When an ecosystem changes so much that a species can no longer survive? That species may become
extinct or die out, causing biodiversity to decrease. And unfortunately, many
of Hawaii's honeycreepers and overall biodiversity have
been lost through extinction. In the past, there were
at least 20 other species of honeycreeper found across Hawaii, but many of them have
become extinct over time. If we return to our
analogy of biodiversity as a safety net? Whenever a species goes extinct it's like a knot becomes undone and parts of the net start to fall apart. A decrease in biodiversity is often a result of human activities which is especially clear
in the Hawaiian Islands. In the last few hundred
years, agriculture, grazing, logging and development
have taken almost half of Hawaii's forest cover. And along with it, a big
part of its biodiversity. Humans have also brought
non-native animals like rats and feral pigs to Hawaii, which have changed or
destroyed native habitats. Plus, new diseases and climate change have led to the extinction
of many Hawaiian species. When an ecosystem loses biodiversity, it doesn't function as well. If 'ohi'a starts to disappear
from Hawaiian forests? It's not just the 'i'iwi that loses an important food source, but the entire ecosystem is affected. In fact, scientists often look at how complete an
ecosystem's biodiversity is in order to measure
the ecosystem's health. The safety net of
biodiversity is supported by having lots of different species, which allows the ecosystem to cope with natural disasters like
drought, storms and disease. With more biodiversity,
ecosystems are stronger and more resilient so
they can recover quickly. But, with less biodiversity, ecosystems become more vulnerable. I told you a lot about how
Hawaii is losing biodiversity, however, there is cause for some hope. The nene, or Hawaiian
goose, nearly went extinct. There were less than 30 birds
in the wild 50 years ago. Now, thanks to lots of conservation work to improve the habitat for those species, there are over 3,000 nene
throughout the islands. We humans are part of
earth's biodiversity too. We are components of
the ecosystems we touch. So if we have the power
to hurt these ecosystems, we have the power to
protect and heal them too. Aloha.