meters from the low tide point. This resulted in a total of 8 counts at the sheltered site and 7
counts at the exposed site. The absolute number of organisms or percent coverage determined
in each count was used to rate the frequency with which particular organisms were present as
absent, rare, occasional, frequent, common or abundant (see appendix a, the sample data
collection sheet for a more detailed description). The first project, the measurement and
comparison of the length and age of Fucus vesiculosus and Ascophyllum nodosum. was carried
out at the more sheltered site. The age of Fucus vesiculosus was determined by counting the
number of bladder pairs and likewise the age of Ascophyllum nodosum. was determined by
counting the number of bladders. For Fucus, the age is the number of bladder pairs and for
Ascophyllum it is the number of bladders. The length of each algae was also measured using a
ruler. Twenty plants of each species, chosen randomly, were measured. Addtitionally, the
presence of Polysiphonia lanosa growing on the Ascophyllum samples was noted as was the
age of the Ascophyllum when the Polysiphonia first appeared.
The second project was completed on the more exposed site. Counts for the number
of individuals of the Patella species of limpets and Actinea equina individuals were conducted
for twenty adjoining 0.5 x 0.5 meter quadrats in a straight line. The counts were done in the
Eulittoral portion of the shore. The measurments were taken starting higher up on the shore and
working in a line straight down the shore to a lower area.
Results and Discussion:
Many differences were found between the two different sites (for actual frequency data
see appendix b). In comparing the two sites there were a few species that were found
exclusively or nearly exclusively on shore or the other. The lower zones of the sheltered site
were heavily inhabited, even dominated by brown algae and in particular by Fucus serratus.
This contrasted sharply with the more exposed site where no brown algae of any species was
found. Additionally, The sheltered site had sponges and hydroids, both of which were absent at
the more exposed site. On the other hand, the exposed shore had abundantChthalamus species
of barnicles and frequent Himanthalia elongata, a brown algae, which were not found on the
sheltered shore. Top shells, particularly Gibbula umbilicalis, and Littorina neritoides were
abundant on the exposed shore but were not present on the sheltered shore. Also on the
exposed shore Mytilus edulis , the mussels, and Paracentrotus lividus, the purple sea urchins,
were abundant, and Actinea equina, the red sea anemones, were occasional while none of these
species were found on the sheltered shore site. This being said however, there were similarities
between the sites as well, for example neither site had more than a few individuals of Laminaria
species or the other kelps other than Himanthalia elongata. Also Littorina saxatilis was absent on
both shores and both shores had many Balanus species barnicles and Patella species limpets.
Ballantine’s exposure scale was then applied to both shores. Based on the presence
and absence of the particluar species used by Ballantine to classify the shores, the more
sheltered site can be classified as a fairly sheltered shore, although within this classification it
leans toward the more sheltered side. This is because it did exhibit some characteristics of a
sheltered shore even though in the end more characteristics pointed to the fairly sheltered
classification. Using the same technique, the more exposed site can be classified as an exposed
shore but like above it leans within this category, this time toward the very exposed side. Again
this is is because even though there were more characteristics pointing to the classification of
exposed shore, there were some characteristics of a very exposed shore present. This is also a
testiment to the fact that these categories do not have clearly defined boundaries and they merge
into one another.
The resluts of the first project, the measurement of the size and age of Fucus vesiculosus
and Ascophyllum nodosum. were only were analyzed in a number of ways (see appendix c for
the data for Fucus vesiculosus and Ascophyllum nodosum). First, the length of the sampled
individuals of Fucus vesiculosus was plotted against the age of each individual and a regression
line was calculated. It turned out that for Fucus vesiculosus, there was almost no correlation
between length and age as was indicated by the very low correlation coefficient generated from
the calculation of the best fit line, the correlation coefficient, R, was R = 0.109 when a perfect
correlation is R = 1.000. Following this analysis the average, max, min and median age and
length were calculated for Fucus Vesiculosus (Table 1). Then the length and age were plotted
against each other for Ascophyllum nodosum. The correlation to the regression line was much
higher (R = 0.845) for Ascophyllum nodosum than for Fucus vesiculosus, suggesting a
correlation between length and age. Then the average, max, min and median age and length
were calculated(Table 1). The presence of Polysiphonia langosa was also analyzed. It was
found that the average age of the Ascophyllum nodosum at which the Poysiphonia langosa
begin growing on it was 2.2 years. Additionally, it was found that 65 % of the Ascophyllum
nodosum individuals sampled had Polysiphonia langosa growing on them.
Table 1
Average
Max
Min
Median
Age of Fucus
vesiculosus
5 years
11 years
2 years
4.5 years
Length of Fucus
vesiculosus
0.51 meters
0.84 meters
0.30 meters
0.49 meters
Age of
Ascophyllum
nodosum.
5.8 years
13 years
1 year
6 years
Length of
Ascophyllum
nodosum.
0.96 meters
1.50 meters
0.38 meters
0.90 meters
From the comparison of the average, max, min and median age and length of the two
species of brown algae, a few conclusions can be drawn. First, the average size of the Fucus
vesiculosus is smaller than that of the Ascophyllum nodosum. Second, the average age of Fucus
vesiculosus is less than that of the Ascophyllum nodosum. Third the average length per year of
for Fucus vesiculosus (0.10 meters per year) is less than that of Ascophyllum nodosum (0.17
meters per year) suggesting that the latter species grows faster. These conclusions must be
carefully interpreted however because the sample size was so small, only 20 individuals of each
species.
The second project, the measurement of the number of individuals of Patella species
limpets and Actinea equina, was analyzed in a similar fashion to the previous project. First the
number of each species was plotted against the quadrat number, with higher numbers being
further down the shore, and a regression line was fit. No strong correlation was found for either
the Patella species limpets (R = 0.405) or the Actinea equina (0.313). This is not wholey
unexpected however, as the zone measured layed entirely in the eulittoral zone and the habitats
in the different quadrants were therefore quite similar. Next the average, max, min and median
number each species per 0.25 square meter was calculated (table 2). These results show, at
least in this zone of the shore, that the Patella species is more common than the Actinea equina
although, as in the first project, the sample size is again small.
Table 2
Avg number per
0.25 square
meter
Max number per
0.25 square
meter
Min number per
0.25 square
meter
Median number
per 0.25 square
meter
Patella species
76
144
27
81
Actinea equina
28
144
2
11
Conclusions:
This investigation clearly shows how different shores are due to different levels of
exposure. The first shore was classified as a fairly sheltered shore according to Ballantines
exposure scale while the second was classified as an exposed shore. It was clearly visible in
examining which organisms were present at each site that some organisms prefer the more
sheltered type of shore while others prefer a more exposed environment. Additionally, some
organisms were present in high numbers at both sites and therefore probablly don’t care about
the level of exposure as much as the organisms present at only one site or the other.
