Chamaesipho Brunnea Research Paper

Biotic factors affecting the distribution of species Chamaesipho brunnea and Lepsiella scobina

The two species C.brunnea and L.scobina share a predator relationship, which, along with other biotic factors and their tolerance levels determines their distribution on the rocky shore. The C.brunnea has a fundamental niche of MTZ-HTZ, which means that it could hypothetically live anywhere in those zones if no predation and competition (mainly interspecific) were present. However, since predation and competition is present in the intertidal zone, the realised niche of the C.brunnea narrows down to the HTZ. This (the realised niche) is the zone that the C.brunnea can actually occupy due to relationships with other organisms, such as predation and

This is because the C.columna have a wider fundamental niche (LTZ-HTZ) than the C.brunnea (MTZ-HTZ) and are able to live anywhere in the intertidal zone. Therefore, if the C.brunnea were to be removed from the upper intertidal zone, the C.columna would easily spread into that area, as they are able to survive efficiently in any tidal zone. For this reason the C.brunnea must be competitively excluding the C.columna from the HTZ through a slight advantage of an adaptation, as the C.columna are more abundant in the tidal zone below the C.brunnea. The advantage allowing the C.brunnea to be the superior species while competing is most likely their structural adaptation of being larger than the C.columna. As the C.brunnea is the larger species, they are able to occupy more space on the rock surface and prevent the C. columna from extending their distribution into that zone or getting a spot on the rock surface. Also, since the C.brunnea is larger they will be able to conserve more water in their shells. and, in doing so, lose water at a slower rate. This is in comparison to the C.columna who are smaller and will therefore conserve a lesser amount of water in

For this reason, since the C.columna has a wider fundamental niche of LTZ-HTZ than the C.brunnea (MTZ-HTZ) they are able to efficiently feed in any of the three intertidal zones, while the C.brunnea is only able to feed in two. This links with how the C.brunnea are better adapted for living in the HTZ than the C.columna, who are better adapted at feeding in the LTZ-MTZ. Therefore, the C.columna are able to competitively exclude the C.brunnea from the MTZ (where their niches overlap) and restrict their distribution to the upper shore because they have the wider fundamental niche. It is also due to the fact that the C.columna have the behavioural adaptation of being able to settle on another grounded barnacle, while the C.brunnea do not. Because of this, the C.columna are better able to increase their population whilst decreasing the population of the C.brunnea in the MTZ as they are able to occupy more space. However, in the HTZ the C.brunnea have the fitter structural adaptation of size and exposure tolerance and through that they are able to restrict and competitively exclude the C.columna from the HTZ, though the C.brunnea now have a narrower realised niche