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Summary Lectures Marine Animal Ecology MAE-30306
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Summary of all the lectures of Marine Animal Ecology MAE-30306.
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Marine Animal EcologyLecture 1/2: Introduction
Animal ecology: the study of animals in relation to the ecosystem in which they live. Marine
animal ecology is different because of the different environment and different animals.
Gorgonian: animal with a backbone with horns (no calciferous backbone).
What makes marine animals and ecosystems different?
- aqueous versus gaseous environment
- food availability: easier to obtain food, which has enabled the sedentary lifestyle (immobile
animal attached to substratum)
- filter feeding: does not exist on land.
- larval dispersal: easy way to reproduce
- less energy into stability
- trophic levels
- pressure / light / pH
- gas exchange: oxygen availability (less O2 in water)
- locomotion
Why study Marine Animal Ecology?:
- To explain the patterns that we see
- The current situation: formation, distribution and functioning of ecosystems
- A new situation: responses to changes
- To enable conservation, utilization and
collaboration: Building with Nature.
Traits: features and capabilities that animals
possess under a specific combination of
abiotic/biotic factors (for their functioning in environment). Can be
Morphological: different morphology for different environments: mouth size
determines which prey that a fish can catch.
Physiological: for example: the rate at which sponges can pump and filter water
determines the efficiency of food uptake, energy balance and potential for growth and
reproduction.
Reproductive: mass spawn vs one young or taking care of young vs no parental care.
Trait based ecology: when describing ecological processes, we look at functional groups
rather than at species.
Interactions between species: competition, trophic interactions and symbiotic interactions.
Competition is often related to:
Space: some animals make chemical and release them to compete with each other:
chemical ecology
Food
, Chemical ecology: chemical warfare in marine ecosystems. Some animals make toxic
chemicals (sponges and tunicates) and are used to chemically deter the other organisms in
the surroundings. These weapons make the animals unsuited for consumption by predators.
Trophic interactions: predator prey relationships: interact through physical and chemical
cues. Crabs vs mussels. With low water flow, mussels are not eaten, but when the flow is
bigger, the mussels don’t feel the crabs, so they move and are eaten. Crown of thorn: coral
eater, but sometimes they bloom up and eat an entire coral reef. These outbreaks relate to
nutrient inputs (eutrophication). food web ecology.
- Pelagic and benthic system:
Top-down control: when presence of apex
predators determines what happens further
below in the food chain. They control the
amount of mesopredators and smaller
carnivores etc.
Bottom-up control: nutrient inputs govern how
much a system can produce (starfish vs crown
of thorn fish).
Trophic cascade: the effect when the apex
predator is removed from the environment. This happens due to fishing. In a lot of coral reefs
also the mesopredators are removed, so you get a lot of small herbivores/carnivores still
stable (but only if the small fish are still in
the environment).
Benthic-pelagic coupling: the benthic and pelagic communities communicate with each other
and exchange resources and energy. Example is the sponge loop: sponges (the benthic
component) take up dissolved organic matter from the ambient seawater (from the adjacent
pelagic system). Sponges convert this resource into cellular material and ‘throw it out’, so
that bottom-dwellers, such as shrimps and sea stars can eat it. In this filter feeding way
pelagic material is put back into the system and eaten again.
More interactions:
3 types of symbiosis
Mutualism + + 1). Coral and algae. The coral provides a protected
environment away from predators, whereas the algae
provide the host with metabolic energy through the
excretion of excess photosynthesis products that are
translocated to the host.
2). In glass sponge 2 shrimps are living: a male and female.
Male and female give food via excretion and the sponge
gives them protection.
, 3). Crabs live on corals to hide from predators. When a
COTS approaches the coral host, the crab uses its scissors
on the soft body parts of the sea star, so that is moves away
from the coral. In this way the coral is protected by the crab.
4). Spiny lobsters live close to moray eels. The lobster is a
potential prey for the eel, but is usually not attacked. The
octopus is a preferred prey for the eel, whereas the lobsters
are food for the octopus. By living together, the lobster gets
protection and the eel gets his octopus for food.
Commensalism + 0 1). Whale with barnacles (sedentary crustaceans).
Barnacles are moved through sea (for filter-feeding). The
whale does not benefit from the presence but is not
impaired by the presence.
2). The sponge grows on gastropod shells occupied by
hermit crabs. The crab moves the sponge to new places,
but don’t give any benefit to the crab.
3). Flatworm lives on stony surface of coral, but now we
found that it is a parasite, because it eats the prey that the
coral catches, eats the protective mucus of coral and
shades the zooxanthellae, which impairs photosynthesis.
Parasitism + -
Lecture 3: Ocean physics and early life stages: larval dispersal.
Larval dispersal in
the pelagic and
benthic environment.
Larvae are
distributed through
the water flow.
This water flow
influences animals:
drag forces,
communication,
settlement, waste
removal, gas
exchange and
feeding possibilities:
- high flow: food
particles flow away,
- low flow: no
nutrients
Fluids and motion: movement of water: flow/current
Process driver
Heat transfer Convection Flow
Conduction Gradient
Mass transfer Convection Flow
Diffusion Gradient
Organisms Convection Flow
Swimming organism
Swimming can be controlled: nekton, but also uncontrolled:
plankton.
, Reynolds number: parameter to describe the flow environment around a solid object. Ration
between dynamic forces and viscous forces. Viscous forces have a different effect, due to a
different grip on the water, when you are small then when you are big.
- Laminar flow: <Re: viscous forces are dominant,
characterized by smooth, constant fluid motion.
- Turbulent flow: >Re: inertial forces are dominant,
which produce vortices and other flow instabilities.
Boundary layers. When water is free flowing, it has a
different velocity then when this waterflow
approaches an object (sea floor). Close to sea floor,
the water flow is low. The water layer in which the
flow regime is affected by an object is called a
boundary layer. Very close to the object, one can find
a layer that is entirely stagnant: no water movement
= diffusive boundary layer (DBL), because diffusion is
the only mechanism of mass transfer in this layer.
The thickness of this DBL determines the capability
of an organism to take up molecules (oxygen, nutrients) out of the seawater. A high Re: low
DBL thickness. A rough surface have a higher Re than a smooth surface, and thus the flow
pattern around the rough surfaces is more turbulent than around the smooth surfaces. This
has positive consequences for gas exchange for organisms living on rough surfaces.
Laminar flow: thicker boundary layer: more problems with gas exchange.
Rough surface: creates turbulent flow layer. So, when an organism is sitting on a smooth
surface: more problems with gas exchange then on a rough surface.
Flow and boundary layer have profound effects on early life stages.
Reproduction and recruitment
First step in reproduction: the production of offspring
- K strategy: few offspring, intensive nursery, live bearing
- r strategy: much offspring, little to no nursery most marine animals.
Second step in reproduction:
- Recruitment: the successful establishment of a new generation.
- Successful = the new generation starts to reproduce itself (closed life cycle). This can be
very different for all animals. Some are sexually mature after 2 years, some after 150 years.
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