DiscussionDue to different types of habitats on the whole of the rock

platform, there is a great diversity of organisms, all adapted to being in a specific environment or at least tolerating the constant change in surroundings during tidal cycles. Many of these organisms are of the adaptation to specific environments. As such, they are found most in abundance a part of one type of zone, while being distributed thinly over the rest or not at all. For example, the chiton is found in most abundance in Quadrat 1, which is in the low tide level of the intertidal zone. From there on it found less frequently the further away you get from that part of the zone, until it can no longer be found, starting from around the upper part of mid-tide level of the intertidal zone. Its specific adaptations and hinder its abilities to survive in other areas other than its own habitat, therefore it is restricted to the low to mid-tide level, being distributed over that area but in diminishing abundance the further it is from the low-tide level.

The zones can be defined by the habitats they create due to their amount exposure to air (whether submerged in water or not), their temperature, salinity, exposure to wave action, light availability and aridity. These are the abiotic factors affecting the abundance and distribution of the organisms across the zones.

The spray zone, or supralittoral zone, lives up to its namesake. This zone is the elevated part that is just above the high tide mark. It is also when the marine meets terrestrial. As a result, its only moisture is gained from the frequent sprays of water from waves in high tide. This part of a rocky shore is only submerged during extreme high tides, usually when there is a storm. The zone is subjected to exposure to air, as it is not submerged. It also tolerates all ambient temperatures according to the weather, whether hot or cold. The salinity is fairly low as it is frequently exposed to freshwater from rain, which dilutes any seawater it has accumulated. The species that thrive here are mostly barnacles, pheasant shells and periwinkles. The diversity of organisms is not large and the abundance of some organisms, such as the striped conniwinks and variegated limpet, are found more frequently in other zones. The harsh environment of constant endangerment to desiccation (drying out) in the sun is the culprit. Only some species have adaptations to live somewhere with prolonged dryness. Biotic factors such as food availability also affects their abundance. For example, for the variegated limpet, its food source of certain algae can only be found in the intertidal zone. Hence only at some times will it venture to the lower parts of the spray zone, in further search of food. Other organisms, like the barnacles and periwinkles, thrive in this area as they have adaptations to reduce water loss or just prevent drying out. All in all, the types of animals found here depend on the food available to them and the adaptations they have to survive in a more arid environment without drying out. There are plants that also live in the spray zone, such as lichen,

which is highly capable of absorbing water, making the environment in the spray zone appropriate for it. However, it was not found in the study area.

Since there is a very gradual transition of the spray zone to the intertidal zone, it is sometimes difficult to discern where each zone starts and end as there is no obvious indication; likewise with the transition of the intertidal zone to the subtidal zone. Some organisms usually found in a particular zone are versatile enough overlap from one zone to the next. Sometimes the organism may be found further off than where it should be, with undeterminable reasons. Therefore it can be confusing to decide which zone is which, based solely on unreliable organism distribution. The submergence of the zone in seawater cannot give a distinct boundary to where a zone ends or starts, as the wave action and tidal cycles offer a constantly changing submergence level.

The intertidal zone was characterized by the greatest diversity and distribution of species it had during the study. Also known as the mid-littoral or just the littoral zone, the intertidal zone has three levels, the high-tide level, the mid-tide level and the low-tide level. The high tide level shares many characteristics with the lower part of the spray zone; it harbors quite a few of the same species like barnacles, the dominant species of these parts. Barnacles are suited to the drier environment that the high tide level and spray zone provide, due to their adaptations. Found in less abundance than the mid-tide level are the likes of top shells, limpets, and chiton. This is mainly due to the inability to adapt to such a harsh, mostly dry environment like the spray zone. The high-tide level is only covered by the tide during extreme high tides, that is, only a few hours each month.

The mid-tide level sees to the most diversity and abundance of organisms found. It can be judged by seeing the sheer amount of intertidal tubeworms reside on the rocks. The mid-tide level is constantly submerged and exposed in each tidal cycle, giving rise to a copious amount of organisms that rely on the tides to bring them food and moisture. It is here where limpets, top shells, conniwinks, pheasant shells, the little horse mussel and predators like the wine-mouthed lepsiella are found in most abundance. Limpets, conniwinks and top shells are distributed most evenly along this area. Many plants are also found in abundance, most notably Neptune’s Necklace. The Neptune’s Necklace can gain enough moisture during the tidal cycles and receives enough sunlight to survive in the mid-tide level; it provides a microhabitat for the mollusks mentioned to live in its moist areas, also providing cover from their predators. As a biotic factor, it can also be a source of food for these animals. Other plants are found in significantly less abundance, most of them are washed up to the mid-tidal level, being in more adapted to low-tide levels or the sub-tidal zone.

The low-tide level usually has the most diversity of organisms as it is submerged for most of the time and only

exposed during the lowest of low tides. It borders on the shallower part of the subtidal zone. There is hardly any need for organisms to adapt to living with constant dryness. Although diverse and teeming with life, hardly any of the organisms found in the mid-tidal area are found here. They are more adapted to living in the constantly changing environment. Organisms are primarily marine and may not be able to survive in prolonged periods of dryness or extreme temperatures (due to the submergence in water, this level is hardly exposed to the weather and thus temperature is fairly constant.) More marine plants are found due to better water coverage, notably strap weed, emteromprha and coralline algae. They can receive their needed moisture readily and light easily reaches the plants through the shallow water for photosynthesis. The normal salinity also makes for easy survival in the low-tide zone. Since the area is shallow, large predators cannot reach it easily, making it popular for many organisms to live in. Animals like the tall-ribbed limpet, chiton and the waratah anemone thrive most here. It is interesting to note that it is also distributed along lower parts of the mid-tide level, although in less abundance than in the low-tide level. This is contingent to the abundance of vegetation it feeds and lives in. The vegetation is more concentrated in the low-tide zone, though also scatters sparsely in other levels.

The subtidal zone was not ventured into for area-study. Also known as the sublittoral zone, it is the coastal area that is always marine. It is submerged even under the lowest tides. Here is where large predators such as fish and crab. Large algae stuck to the sea floor create forests for many varieties of completely marine animals. None of the animals found in this zone can be found on the intertidal or spray zone. If they are found there, it is usually because they washed up by accident. The subtidal zone extends to more than 20m deep. As a result, availability of light will be less the further down it is; it cannot reach as well that far down. Salinity is normal for the organisms as the area is completely submerged.

The ribbed top shell was found in great abundance along the whole transect line. It was also distributed quite evenly, although there were slight dips in numbers the closer it got to the two extreme points, Quadrat 2 and Quadrat 9. They had 6 and 8 shells each respectively. There were no ribbed top shells in Quadrat 10 or Quadrat 1. It thrived most from Quadrat 3 to 8, with 19 being the most shells found in a single Quadrat, Quadrat 6. This signifies that the ribbed top shell is most adapted to living in the mid-tide level of the intertidal zone, this being the area it was distributed along in the most abundance. It is less suited to the low-tide level and high-tide level. It is in most abundance in the mid-tide level as the tides constantly bring in the algae it feeds on and the oxygen in the water that it needs.

Being in the mid-tide level, the most prominent abiotic factor affecting it is the constant change in tides and strong wave action. The change in tides means that the ribbed top shell has to adapt to being submerged and exposed all the time. To achieve this, it has a structural adaptation of a thick, impermeable shell.

The shell shields it from the immediate danger of the crashing waves, and also retains water when the tide is low and where it lives is exposed and vulnerable to drying out in the sun. It does so by sealing the opening of its shell in with an operculum i.e. a lid. Being white in color, the ribbed top shell is very conspicuous against the dark rocks it latches on to. The thick shell also helps defend it to an extent from predators, a biotic factor. Birds and other predators may find it hard to penetrate the shell to get to its flesh and will be deterred from trying so. If disturbed, it can use the operculum to protect itself. To avoid further drying out, it can shelter in small crevices to avoid the drying wind. Water may also be retained in these crevices, a bonus. The whiteness of its shell does not absorb heat well, so it is a structural adaptation, which helps it avoid overheating in the time of exposure to the sun. As a snail, it is not surprising that it has a very slow metabolic rate. This physiological adaptation can be helpful as it reduces the need for oxygen consumption, and so it does not need seawater all the time for its oxygen fix. However, it can meet its downfall this way as it will be too slow to escape predators like the wine-mouthed lepsiella, which can easily gain access to its flesh by dissolving a hole in its shell and sucking out the insides. As a grazer, another biotic factor for the ribbed top shell is the food: the algae on the rocks. It uses a rasp-like tongue to scrape of the algae it attaches itself to, whether microscopic or larger green, red or brown algae. As it moves along, it leaves a chemical trail which it can use to trace back to a food source it wants to come back to or find its way back home. Competitors for food are another biotic factor. They include striped conniwinks and the warrener. Both were found in less abundance and distribution than the ribbed top shell, which suggests that they are not as successful as it is in adapting to the environment and grazing food.

Strap weeds are brown algae. They were found in most abundance in the low-tide level of the intertidal zone. Their distribution was very limited, with only Quadrats 3, 4 and 5 having any of them at all. Quadrat 3 had the most, with 85% of it. This is due to the fact that it is a large algae which has to attach itself to the seafloor of shallow water to allow its buoyant fronds room to float. Hence, the low-tide level, along with the shallower parts of the subtidal zone, is where it is found.

As an autotrophic plant, the largest abiotic factor of strap weed is light. Being submerged in water, light is not as easily accessible to it. Hence, it has the structural adaptation of elliptical bladders at the end of its short stalks. These bladders keep its fronds upright in the water by making them buoyant, bringing them closer to the sunlight and thus allowing them to photosynthesize.

Because the algae lives in the low-tide zone and shallower subtidal zone, it is affected by the strong wave actions. It is often washed up onto higher intertidal areas. This is why their distribution can sometimes be more widespread. To avoid this, it has holdfasts of about 1-6cm across, which provide anchoring to

the seafloor. It also exists in large forests, which can better stand up to the strong currents.

Since they exist in large forests, strap weed can be biotic factors of themselves. They compete with each other for the nutrients in the water, and taller strap weed may block the sunlight out for the other weeds. There are animals that graze on strap weed, and sometimes dense aggregations of these animals, such with the case of sea urchins in New South Wales, can graze the zone bare of the weed. That affects their abundance in the area, but this is the general cycle of the food chain. The grazers find less and less weed to eat and gradually die off, allowing time for the strap weed to grow again. The cycle repeats.

ConclusionEach zone in on a rocky shore sees to different types of

organisms, some of which may be distributed over other zones since they are well adapted to the areas. The spray zone is characterized by being uncovered by the tides most of the times, unless during storms. Hence the constant exposure to sun and freshwater salinity gives rise to little diversity in organisms. Organisms living there would need to be well adapted to living in a dry environment, and must be able to retain water. The intertidal zone has three levels; The high-tide level being very similar to the spray zone and the low-tide level being similar to the shallow part of the subtidal zone. The abundance of some organisms in the low-tide level would be the greatest, as they are more used to being submerged. Their distribution across the rest of the zone would be sparser. The mid-tide level harbors great diversity and distribution of organisms as the constant tidal cycles bring in food all the time. However, organisms living there would need to adapt to constant change in environment, whether exposed or submerged. The subtidal zone is marine and has the greatest diversity and abundance of organisms due to being completely submerged in water, which is preferable for these organisms.

The hypothesis was partially supported. Some organisms were indeed in greatest abundance in the intertidal zone, but for many organisms it is actually more of that they were distributed evenly along the zone (mostly mid-tidal level). Most organisms were found more abundantly in the low-tidal level, where it is closer to the subtidal area. They are more used to the marine life there. The spray zone did have a greater concentration of certain species, but diversity was low and distribution was more even over the intertidal zone.

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