Wednesday, November 30, 2011
Interactions in the Nose Hill pond, by Sarah
Interactions between organisms occur every time organisms have some sort of come into contact with each other. These interactions can be harmful, beneficial, or inconsequential for one, both, or all of the organisms. Here we will be examining six types of interactions between the organisms present in the nose hill pond.
Figure 1. This picture is of the pond, which is located at the southwest corner of Nose Hill. The picture was taken by me on Sept. 22, 2011.
There are many types of interactions that take place between organisms on the hill. The interactions that will be examined in this blog are: predation, parasitism, mutualism, commensualism, intraspecific competition, and interspecific competition.
First, some definitions:
Predation (the predator/prey relationship): when a predator kills another organism (its prey)
Predator: any organism that kills other organisms for food (Freeman, 2008)
Prey: an organism that is killed and eaten by another organism.
Parasitism: a symbiotic term relationship between two organisms that is beneficial to the
parasite but detrimental to the host (Freeman, 2008)
Parasite: an organism that lives on or in a host species and that damages its host.
Host: an individual or species on or in which a parasite lives. (Freeman, 2008).
Mutualism: a symbiotic relationship between two organisms that benefits both (Freeman,
Commensualism: a symbiotic relationship between two organisms where one organism
benefits and the other organism is not significantly affected.
Intraspecific competition: when two or more organisms of the same species vie for the same
Interspecific competition: when two or more organisms of different species vie for the same
Here is a list of the organisms that were identified on Nose Hill
-stagnant pond snail Lymnaea stagnalis
-flatworm Procotyla fluviatilis
-damselfly larvae Agriocnemis femina femina
-water boatmen Corixidae notorectidae
-dytisscidae hydaticus (species of predatory water beetle: common name unknown)
-promenetuss umbilicatellus (small species of snail: common name unknown)
-freshwater leech macrobdella decora
-mallard duck anas platyrhynchos
-cattail typha latifolia
-larger duckweed spirodela polyrhiza
-hornwort ceratophyllum demersum
-mares-tail hippuris vulgaris
-Pondweed potamogeton amplifolius
-deer (identified by tracks left in mud)
Other species of birds, smaller than the mallards, were observed flying around the pond and hiding in the cattails; however, these birds were moving too quickly or were too far away for identification. Evidence of nests, in the form of small, condensed pieces of material, were also found.
Each of these organisms interacts constantly with all of the other organisms. In the interest of keeping this blog relatively short, the examination presented on these species will focus on the organisms highlighted in the list.
Predation is when one organism eats another. Here are two examples from Nose Hill:
- Pondweed is eaten by mallard ducks. Therefore, the duck is the predator and the pondweed is the prey. The ducks are further classified as herbivores, because they are eating plants rather than other consumers.
- Flatworms eat smaller organisms, such as amoebas and water fleas. In this example, the flatworm is the predator and the smaller organisms are the prey. These flatworms are predatory, because they eat other consumers instead of eating producers/plants.
Parasitism is when an organism (the parasite) feeds on another organism (the host) without killing the host.
- An example of parasitism in the Nose Hill pond environment is the freshwater leech. The leech attaches itself onto another mammal, such as a deer or mallard. In this example, the leech is the parasite and the other animal is the host.
Commensualism is when one organism benefits from the relationship while the other organism is neither benefitted nor harmed. Here is an example of commensualism in the pond:
- Deer, birds, leeches, flatworms, and pond snails all use cattails as shelter from predators and weather conditions. The animals benefit by gaining shelter, while the cattails experience no significant benefit or harm.
A mutualism relationship is an interaction in which both organisms gain. Some examples from Nose Hill are:
-When birds take the fluffy seeds produced by cattails and use them to build tests. The bird gets a nice, comfortable nest in which to raise its offspring, and the cattails seeds are spread by the bird. Therefore, both organisms are benefitted.
-Pond snails, which are scavengers, consume and decompose dead cattails and other wastes in the water. The pond gets food to survive and reproduce, while the cattail benefits from the nutrients released by the snail during decomposition.
Intraspecific competition is competition between two members of the same species. For example:
- Cattails grow in groups on the side of the nose hill pond. These cattails compete for space and the nutrients in the soil and water. They compete both for space for themselves and space for their seeds.
- Leeches compete for hosts. The only hosts available for these leeches are a few ducks and the occasional deer or other mammal that come to feed and drink. This means that the leeches compete to gain a suitable host.
Interspecific competition is competition between members of different species.
- The different plants in the nose hill pond compete for space to grow and nutrients in the soil and water.
- Birds compete for the fluff that is released every year by the cattails, for use in building their nests.
The examples of interactions given here are only a few of the wide variety of interactions constantly ongoing in the nose hill pond. However, they should serve to give a good idea of the different interactions that are occurring in the pond.
Freeman (2008) Biology. San Francisco: Pearson Benjamin Cummings
Royer, F.; Dickinson, R. (2007) Plants of Alberta. Edmonton: Lone Pine publishing.
Lahring, H. (2003) Water and wetland plants of the prairie provinces. University of Regina:
Canadian Plains Research centre.
Clifford, H. (1991) Aquatic invertebrates of Alberta. Manitoba: DW Frieson & sons.