# Laminar _Ulva_ Species: A Multi-Tool for Humankind?
## 2 The Biology of _Ulva_ sp.
### Light Intensity
Temperature affects photosynthesis resulting in altered productivity and therefore supplies carbohydrates to the tissue. Temperature response is exhibited through phenological attributes mediated by complex metabolic pathways, such as significantly affecting respiration rates via adenylate control, i.e., ADP/ATP ratios; increasing the content of nitrate reductase, amylase, invertase and peroxidase; and reducing the growth rate as the temperature increases [54]. [PERSON] et al. (2020) [4] identified the optimal effective temperature range for inducing reproduction in various _Ulva_ spp. to be between 15-20 \({}^{\circ}\)C. However, they noted that a difference of 5 \({}^{\circ}\)C is crucial for effectively inducing gametes or spores. Additionally, a temperature difference of 10 \({}^{\circ}\)C is essential for the growth of tropical species [4]. There is the possibility of relating it to the seasons. For example, _U. lactuca_ from Goton, USA, only reproduces in the warmest months at 21 \({}^{\circ}\)C and is inhibited at 25 \({}^{\circ}\)C, while populations of _Ulva pseudocurata_ from the North Sea have approximate weekly reproductive peaks during the summer and peak biweekly during the colder seasons [54]. Another example of the influence of temperature is due to the experiment by [PERSON] and [PERSON] 2011 [85], where they collected a stalk of _Ulva fenestrata_ in Japan (temperature 6 \({}^{\circ}\)C and irradiation at 60 UE/(m\({}^{2}\)s)) and placed it in the laboratory (water temperature 15 \({}^{\circ}\)C and irradiation at 40 EU/(m\({}^{2}\)s)). They found that the reproductive period decreased from 30 to 5 days when the temperature increased from 10 to 20 \({}^{\circ}\)C and ceased at 5 \({}^{\circ}\)C [54]. With this, researchers investigated the relationship between rapid changes in temperature and the induction of gamete release over shorter periods of days and hours. [PERSON] (1988) [86] employed a temperature shock with 2 \({}^{\circ}\)C saltwater to induce sporulation in _U. lactuca_ when no reproduction occurred between samples after 30 days. Plants were withdrawn from 22 \({}^{\circ}\)C containers and cleaned completely in filtered saltwater at 2 \({}^{\circ}\)C before being reintroduced to clean growth chambers with fresh media at 22 \({}^{\circ}\)C. This study involved two reproductive therapies along with a control group. The experiment was limited to these conditions because, within 18 h of washing at 2 \({}^{\circ}\)C, all samples had transitioned to a reproductive state, rendering no vegetative algae available. The author observed that the conversion of vegetative tissue to a reproductive condition occurred almost instantly after washing the algae in water at 2 \({}^{\circ}\)C, and the production of gametes over 12 h was rapid and consistent. [PERSON] et al. [83], working with a tropical filamentous species of _Ulva_ spp., subjected the stalks to a temperature shock (4 \({}^{\circ}\)C) for 10 min, followed by immersion in autoclaved, filtered seawater under a 12-h photoperiod at 25 \({}^{\circ}\)C. Gamete release reached its peak 2 days after the onset of treatment, resulting in an approximately 10% increase in sporulation [83]. In 2017, [PERSON] et al. [87] demonstrated that a 20-min temperature shock at 4 \({}^{\circ}\)C induced an average reproductive response of 94.7% in the tissue of the lamina of _Ulva rigida_ on the fifth day with a two-step process, the first being from high temperature to low temperature and the second the return to high temperature. The results demonstrated that none of the steps is dispensable, as continuous induction of low temperature for 3 weeks, without returning to high temperature, did not trigger reproduction [54]. Some authors have suggested that a minimum of 2 days is required for the transition from the vegetative to the reproductive state and that enhanced reproduction under abiotic temperature shock may be a survival strategy under unfavorable conditions such as occurs in certain animals.