International Journal of Marine Science, 2024, Vol.14, No.1, 6-13 http://www.aquapublisher.com/index.php/ijms 8 species (Sun and Liu, 2004). During spring and summer, increased light and nutrient availability lead to a significant rise in the quantity and variety of phytoplankton and zooplankton, resulting in peak diversity in seasonal surface-floating biological communities. Complex food webs are established between phytoplankton and zooplankton, with different species relying on each other, creating a high level of species diversity. Phytoplankton form the foundation of surface-floating biological communities, absorbing carbon dioxide and releasing oxygen through photosynthesis, providing energy and oxygen to the entire food web. Major phytoplankton species include diatoms, dinoflagellates, and green algae, utilizing photosynthesis to convert inorganic substances into organic matter, serving as the primary food source for other organisms. There is an interdependence between phytoplankton and zooplankton. Phytoplankton provide the energy and nutrients necessary for zooplankton, while zooplankton regulate their population density and composition by consuming phytoplankton. This interdependent relationship plays a crucial role in maintaining the stability and balance of surface-floating biological communities. With the arrival of autumn and winter, changes in the marine environment lead to a decrease in the quantity and variety of phytoplankton and zooplankton, resulting in reduced diversity in seasonal surface-floating biological communities. During winter, most phytoplankton and zooplankton enter a state of dormancy or reduced metabolic activity, with only a few species adapted to cold environments remaining active. Autumn and winter are seasons in the ocean with relatively lower nutrient supply. During this period, reduced nutrient levels in the water, decreasing temperatures, and reduced daylight hours create unfavorable conditions for the growth and reproduction of phytoplankton. Phytoplankton have specific requirements for suitable temperature and light conditions, and when these conditions are not met, their physiological activities are inhibited, leading to a decrease in quantity and diversity, restricting phytoplankton growth. As the foundation of the surface-floating biological community, phytoplankton may face increased predation pressure during autumn and winter. Due to the reduced availability of nutrients and energy, other marine organisms may engage in more intense competition and predation on phytoplankton, potentially resulting in the reduction or disappearance of some phytoplankton species. This decrease in quantity and diversity can directly impact the presence and diversity of other organisms in the entire ecosystem. 2 The Influence of Environmental Factors on Marine Surface-Drifting biological Communities 2.1 The impact of light on surface-drifting biological communities Light conditions have both direct and indirect effects on the marine planktonic community. Light serves as a crucial energy source for photosynthetic marine planktonic organisms. Planktonic plants absorb light energy and utilize photosynthetic pigments to convert it into chemical energy, thereby facilitating the synthesis of organic matter. These organic substances not only provide energy and nutrients for the planktonic plants themselves but also serve as a source of energy for other organisms within the entire food web. Consequently, the intensity and duration of light directly influence the growth and reproduction of planktonic plants (Mohammady et al., 2023), subsequently affecting the structure and function of the entire planktonic community. The intensity and transparency of light determine the depth to which light can penetrate. In the ocean, light gradually diminishes and eventually disappears at a specific depth, forming what is referred to as the light attenuation layer. Planktonic plants are typically found within the surface layer of light, where the light intensity is sufficient to support photosynthesis. Therefore, the depth and distribution of light play a critical role in the distribution and ecological niche selection of planktonic plants, directly impacting the spatial structure of the planktonic community. Different planktonic organisms have varying light requirements and tolerance ranges, which are related to their light adaptation and light response mechanisms. Light adaptation refers to the ability of planktonic organisms to adapt to light intensity and spectrum. Some planktonic organisms exhibit characteristics adapted to strong light environments, while others are adapted to lower light conditions. Light response refers to the physiological and behavioral responses of planktonic organisms to changes in light conditions. For example, certain planktonic plants and animals may vertically migrate to deeper waters under high light conditions to avoid damage caused by excessive light. These light adaptation and light response mechanisms enable different planktonic organisms to
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