Why Sargassum serves as nursery area for fish and invertebrates

Based on my observation, this soft-body plant could have erected in water because of the following reasons. First, the plant needs sunlight for photosynthetic activities. As such, it may erect to enable it tap maximum sunlight for photosynthesis. As the depth of water increases, the oxygen depletion occurs. Therefore, through erection, the plant may be able to reach the maximum oxygen it requires for respiration to occur. In addition, the plant could have erected due to turgor pressure in the cells. During this process, the large sap vacuoles in the plant's cells take up water and make the cells more rigid and turgid. Turgor pressure is caused due to different concentration between the plant sap and the external environment in the case the water body. Through osmosis water then moves to the highly concentrated juice in the cells sap making them turgid which leads to an erection.

(b)    The reasons as to why Sargassum can serve as nursery areas for larvae and fish

Larvae of the invertebrates and fish need a conducive ecological environment that is self-sustaining. In detail, this means a place that has food, water, and air. Therefore, based on my ecological knowledge, I will discuss several reasons as to why Sargassum serve as a nursery area for invertebrate larvae and fish. First, the Sargassum provides a conducive temperature and neutral medium which favor the larval growth. Larvae and fish require a balanced environment that would enable them to grow and multiply. Second, the Sargassum creates an environment that protects both the larvae and fish from predators. The plant has leaves that can be used has hiding ground for larvae and fish. Besides, the colors of the leaves may camouflage them hence keeping the predictors away. Moreover, it served as food for the larvae. Both larvae and herbivorous fish may feed on the leaves. Notably, this presence of food makes the environment ideal for the invertebrates. Lastly, the presence of enough oxygen around plant makes it a suitable breeding ground. Through erection, leaves are push towards the water zone contain sufficient oxygen that could be used by the organisms.

(c)  Summary of Results from Fig 2

    Sargassum plants and APUs, Filamentous

APU, Foliose APU indicated different types of species in each location.  Based on the numbers of species, the Sargassum plant attracted over 60 species in Palm 1 and Palm 2 locations. The numbers of species seem to decrease in other sites. For instance, Fantome 1 and 2 indicated slightly above 32 types of species. Species in brook 1 and 2 varied with some below 20 while others above 20. In Filamentous APU, the number of species in Fantome 1 and 2 were greatest ranging between 60 and 70. The remaining locations had a slightly higher number of species as compared to other species in the remaining habitats. Nonetheless, the number of Foliose also varied according to the sites.  Palm 1 and 2 registered the highest number of species as compared to other locations with the same species. On the same note, the foliose in Fantome 1 and 2, and Brook 1 and 2 indicated the lowest number of species in comparison to different habitats.

Abundance refers to the relative representation of species in a specific ecosystem. Based on the abundance, Sargassum APU, Filamentous

APU and Foliose APU represented difference levels of abundance. Indeed, this could be influenced by the locations and the species of the plants. In considering the area of each habitat, Brook island indicated the highest level of Sargassum abundance followed by the Palm Island. Fantome Island reported the lowest abundance level. In Sargassum, the abundance was most top in both the Brook and Fantome islands with over 600 number of larvae. The high number was also seen in Brook island ranging from 200 to 500 larvae. The Filamentous

APU recorded the highest abundance level however with varying degrees depending on the location.  The results showed that Sargassum APU and filamentous had a similar environment that favored the growth of invertebrate larvae and fish.  Foliose APU recorded the least abundance level in all the locations. Of course, this could be attributed to the unconducive ecological environment it provided for the larval and fish development.

(d) The interpretation as to why invertebrates mainly feed on the Sargassum

Based on the above interpretation, it can be deduced that the invertebrate Larvae feed on the Sargassum because of the following reasons. First, the high number of species recorded showed that the larvae invertebrates and fish found the habitat favorable for their growth. It always the fact that organisms tend to colonize areas that they can acquire food for their essential growth. Second, the high level of abundance is a clear indication that the invertebrate fed on Sargassum plant. The high rate of multiplication was a sign the plant provides enough food for the invertebrate to survive and reproduced.

(e) Which type of APU would you suggest for such mitigation purpose? Why?

The type of APU I would suggest for mitigation purposes is Filamentous

APU. One of the reasons for selecting this species is because it has a similar environment to Sargassum. Indeed, that why it produced almost same results as the Sargassum in both the number of species and level of abundance. Notably, this could be because they had the same ecological characteristics. Second, it had a conducive environment that favored the growth larvae and fish. In general, Filamentous APU exhibited a self-sustaining ecosystem in which all the survival requirements, such as water, food and oxygen were available.