Seafloor EcologyHow to study the marine

environment and the importance of habitats and food webs

The marine environment

• Around 71% of the Earth’s surface is covered by oceans

• Oceans form one of the largest habitats on earth and many parts have only recently begun to be explored

• Studying the seafloor is important to our understanding of how

HabitatsA habitat is an area where a group of animals live and breed. There are many different habitats around earth. Some animals don’t always stay in the same habitat, but move depending on factors such as the season and food.What are some different habitats in the UK?

Image different habitats, desert, cold mountains, rivers & trees, marine

Marine HabitatsLike anywhere else the marine environment provides a number of different habitats for the organisms living there. Due to the size and depth of some marine habitats little is known about them and very few have been explored.

Can you match some of the scientific ocean habitat names with their common definition?

IntertidalPelagic

Benthic

Hydrothermal Vents

Demersal

Near the seafloor

Seafloor

Underwater volcanoes

Open sea

High tide and low tide area

Marine HabitatsThe organisms which live in these habitats make up communities. Communities include all living things (both plant and animal) in a habitat. The habitat and community together make an ecosystem.

Think about your school as an ecosystem, what makes up the habitat and community?

Open OceanThe open ocean, or pelagic zone, is anywhere not near the seafloor or the coast. While this is a large part of Earth’s surface nutrients are dispersed and animals in this habitat often travel long distances.Animals which live in the open ocean around the UK include: seagulls, sharks, squid, seals, basking sharks and salmon.

Rocky seafloorThe rocky seafloor is part of the benthic seabed. Animals here live permanently directly above, on or under the seabed. Many of the animals have adapted to the habitat by clinging onto the rocks or using the material as homes.Animals that live in the rocky seafloor around the UK include: ross worms, amphipods, starfish, octopui and gobies.

Sandy SeafloorThe sandy seafloor is the part of the seabed which is mostly made up of sand sediments. Though it doesn’t look like much would live here there a wide number of animals that call the sandy seafloor home. Animals which live in the sandy seafloor around the UK include: catworms, shrimps and polycheates.

Food• As well as a habitat all living things need food for energy• For many animals this energy comes from other animals• We can classify animals by how they get their energy

Herbivores only eat plant material

Omnivores eat both plants and animals for energy

Carnivores eat only meat or the flesh of other animals

Are these marine animals omnivores, herbivores or carnivores?

Food chains• Food chains are simple

diagrams which show the relationship between predators and prey.

• The image here shows how humans can be exposed to mercury through the food chain.

• As the mercury continues up the food chain the levels get higher. Therefore sharks will have more mercury in them than krill.

• Why is this dangerous for humans?

Trophic PyramidA trophic pyramid illustrates the trophic levels. Trophic means feeding, therefore trophic levels show different levels of feeding. Pyramids like this can also indicate the energy, or amount of living organisms, at each level on the food chain. The pyramid works by splitting animals into categories according to what type of consumer they are.

ProducersProducers make their own food. In the oceans they convert energy from the sun into food through photosynthesis. Examples of producers include seaweeds and phytoplankton.

ConsumersConsumers do not make their own food, instead they consume other living things. Consumers can be herbivores, omnivores or carnivores. There are three levels of consumers; 1st, 2nd & 3rd. Sometimes the pyramid will have an Apex predator at the top, this is an organism which has no predators and is at the top of the food chain.

DecomposersDecomposers do not fit into one level of the pyramid as they are everywhere. These are the bacteria that feed the life cycle by breaking down waste or dead organisms.

Marine pyramidMovement of energy from one trophic level to the next is not simple. The animals at each level only consume around 10% of the energy of those they are eating. It takes millions of organisms at the bottom to feed those at the top.

Food webs• Food webs are far more complicated than food chains and trophic

pyramids. • Food webs show the complex relationships between producers,

consumers and decomposers in a habitat.• A food web that links all animals and plants in an environment would

be very confusing and hard to understand. • To simplify food webs specific animals are used to represent a

whole group.• By studying food webs scientists can learn about how fishing,

pollution and other marine industries affect the oceans and the animals living there.

Complicated Food Web

Simple food web

RECs• All of the information we know about marine habitats and feeding

patterns comes from scientific studies.• Scientists are continually studying the seafloor to find more

information about it.• Recently UK scientists have been involved in the Regional

Environmental Characterisation surveys or RECs for short.• These were some very large and important studies which looked at

the archaeology, geology and ecology of the seafloor around the UK.

Marine Ecology• A huge number of scientists were involved in creating the four RECs. One

important group were the marine ecologists.• Marine = related to the sea or saltwater environment• Ecology = the study of living things and how they interact with each other

and their environment• Marine ecologists study living things in the ocean, or marine environment,

and how they behave and interact with their environment.• During these studies marine ecologists sampled organisms on the seafloor

to get an idea of abundance and seafloor ‘health’.• This information can be used in the future to assess whether the seafloor

has changed and if we are using it sustainably or not.

Habitat

• Marine ecologists can study habitats using many different methods.

• To view the animals in their habitat scientists use still or video cameras.

• Remote Operate Vehicles are sometimes used to carry the camera to hard to reach places.

• Divers are also used in small areas where the study is very specific.

REC Habitats

• Ecologists studying the REC areas found a huge range of different habitats.

• These habitats were determined by the type and amount of substrate.

• Some of the habitats were determined to be important for conservation.

• For example, a bedrock habitat with a thin layer of gravel is very important for Black Bream fish, as this is where they build nests.

Animals• To collect animals to study the

scientists use Beam trawls and Hamon grabs.

• Beam trawls involve towing large nets across the seafloor.

• The net is held open by a large metal beam.

• These nets pick up creatures which live on and near the seafloor.

• Hamon grabs work by lowering large claws onto the seafloor from a boat. The claws then close collecting organisms and seafloor.

REC Animals

• Ecologists studying the REC areas collected and analysed a large number of different animals.

• Some of the animals are very important.

• For example, Ross Worm reefs provide habitats for other animals.

• The amount of American Slipper limpets found in the South Coast indicate how much this introduced species has taken over.

• The table here shows the names of just some of the species found during these studies.

Food Chain• The scientists focused on

measuring and recording epibenthic fauna.

• Epibenthic fauna are those animals which live on and in the seafloor.

• They know that any changes to these organisms will ripple up the food chain causing problems for many other animals.

• Scientists discovered that not only were Ross worms providing food but also a habitat for other animals to live and breed.

Human Impact

• Now that you have seen how animals in the food web interact you can imagine what would happen when humans impact on the environment.

• The RECs provide a benchmark for how healthy the seabed is, future studies can measure any changes.

• It is important that we keep investigating the seafloor so that we have warning of any changes that are going on.

Discussion Questions

• Why are food chains and webs important to understand?• What factors influence animals in a habitat?• What would happen to top consumers if there was no sun?• Why do we need to use the sea sustainably?• How do we know if we are using the sea sustainably?• What do you think scientists should focus on?