s Im interested in the effect of pH levels on ctenophore egg

s. I\'m interested in the effect of pH levels on ctenophore egg production. bring 40 ctenophores of various sizes back into the lab and, by hand, select 20 individuals which are placed in individual 500mL beakers filled with artificial seawater that has been set at a pH level of 6.5. l then take the remaining 20 ctenophores and add them to individual 500 mL beakers filled with pH 8.0 artificial seawater. (Note: I used one initial batch of seawater which I adjusted with HCl or NaOH as necessary to get the assigned pH). The next morning, l collect the eggs that the ctenophores have released into the water and find that the pH 6.5 individuals have released mor eggs on average. therefore conclude that pH does have an effect on ctenophore egg production. Is this conclusion justified? Why or why not?

Solution

ctenophores have a simple life cycle. ctenophores carry out their entire life cycle in the plankton, so they are considered to be \"holoplanktonic\". Most, but not all, species of ctenophores are hermaphroditic, meaning that a single ctenophore carries both male and female gonads. This means that a single animal can produce both eggs and sperm. Ctenophores spawn these eggs and sperm freely into the sea, where the sperm must first find the eggs, and the eggs are then fertilized. Fertilized eggs develop through a larval stage that hatches out of the free-floating fertilized egg and gradually grows into an adult ctenophore (the planktonic larvae of benthic ctenophores settle to the bottom before taking on their final adult form). It is thought that most of the hermaphroditic ctenophore species are self-fertile, which means that it only takes one ctenophore to make more ctenophores. Also in the few cases where it has been examined, it appears that ctenophores reproduce at a young age (small size). Whereas most medusae grow to adult size before beginning to produce eggs or sperm, ctenophores seem to produce small numbers of gametes before they reach adult size, and thus may have very rapid generation times, resulting in rapid population growth. After attaining their adult size, ctenophores will spawn eggs and sperm daily (for weeks), as long as there is sufficient food available in the plankton. Starved ctenophores stop producing gametes and then the ctenophore begins to shrink in body size in the absence of food. When food becomes available, the animal grows again to some predetermined size and then begins to put energy into gamete production again. Invasive species in marine environments have gained public and scientific attention due to their documented direct and cascading effects, Ecosystems disturbed by, for example, eutrophication or overfishing are especially vulnerable to invasions . The ctenophore , native to the east coast of the Americas, is such a successful invasive species .The invasion success of ctenophore is partly due to its high reproduction capacity, being a hermaphrodite with a daily production of up to 14,000 eggs ind1 the reproduction rates of the ctenophore are considerably reduced under the low salinities that are characteristic of the central Baltic Sea. Hence, salinity acts as a bottle neck for the population expansions.