International Journal of Marine Science, 2024, Vol.14, No.1, 6-13 http://www.aquapublisher.com/index.php/ijms 10 Planktonic organisms play critical roles in marine food webs, including primary producers, grazers, and decomposers. Temperature changes can influence the growth rates, feeding habits, ingestion rates, and reproductive strategies of planktonic organisms, thereby altering their positions and influence within the food web. For instance, an increase in temperature may accelerate the growth rates of phytoplankton, which in turn affects the grazing pressure and competitive relationships among zooplankton. Furthermore, temperature also impacts various biological interactions among planktonic organisms, such as symbiosis, predation, and competition, further reshaping the structure and ecological functions of the entire planktonic community. Temperature is one of the key factors regulating the reproductive rates and seasonal life cycles of planktonic organisms. The reproductive and developmental processes of many planktonic organisms are closely tied to seasonal temperature changes. Elevated temperatures can stimulate the reproduction and development of planktonic organisms, reducing metabolic cycles and generation times. Conversely, lower temperatures can delay reproduction and development, leading to constraints on the breeding season and adjustments in life cycles. The impact of temperature on the reproduction and life cycles of planktonic organisms directly determines the dynamics of their populations and geographic distribution. Different species of planktonic organisms have varying temperature tolerance ranges and preferences, thus, their geographic and vertical distribution is influenced by temperature limitations (Xie et al., 2019). For example, some phytoplankton and zooplankton prefer warmer waters, while others thrive in cooler waters. Furthermore, temperature fluctuations can also affect the seasonal migration behaviors of planktonic organisms, some species migrating to higher latitude or deeper waters during warmer seasons to avoid the impacts of excessive heat. Changes in temperature can directly influence the structure and functioning of marine ecosystems through shifts in the geographic distribution and migration patterns of planktonic organisms. 2.3 The impact of salinity on surface floating biological communities Salinity is a critical environmental factor in marine surface floating biological communities, affecting the physiological adaptation, feeding and nutrition, ecological functions, and geographic distribution of planktonic organisms. Different species of plankton have varying adaptability to salinity, with some capable of surviving and reproducing within a broad salinity range, while others are more sensitive to salinity fluctuations. Changes in salinity can influence vital physiological processes in planktonic organisms, such as cell osmoregulation (Figure 3), ion balance, metabolism, and nutrient ingestion. High salinity levels can lead to cell dehydration and disrupt ion balance, while low salinity may result in cell swelling and insufficient ion concentration. Planktonic organisms adapt to different salinity environments by regulating the concentration of solutes inside and outside cells and the accumulation of osmotic regulating substances in cells. Figure 3 Cell proliferation of marine plankton (Image source: https://cn.bing.com/) Plankton primarily mainly obtain energy and nutrients by ingesting dissolved organic matter, suspended particles, and other planktonic organisms. Changes in salinity can affect the feeding behavior, food selection, and ingestion
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