Environmental Sex Differentiation In Fish (Hb 2015) Hardcover

Fish are a vital, renewable natural resource, and any disruption to their reproductive abilities caused by human activities can lead to serious socioeconomic impacts. The wide range of human influences on sex differentiation and reproductive health in fish has made it challenging to address comprehensively—this book represents the first attempt to do so. In contrast to mammals, the expression of many sex differentiation genes in fish is heavily influenced by environmental factors, making environmentally driven sex differentiation a common phenomenon in fish species. While overfishing doesn't seem to alter this process, overcrowding in aquaculture environments does—primarily by limiting access to food, which affects development. Additionally, numerous synthetic chemicals used globally act like natural hormones. For instance, endosulfan—a pesticide still used in many developing countries—can mimic hormones and cause feminization in fish. This book uniquely examines endocrine disruption from two developmental perspectives: the sensitive early "labile" stages and the more stable adult stages. It reveals that exposure to endocrine-disrupting chemicals (EDCs) during early stages can cause permanent sex reversal, while exposure during adulthood primarily results in reversible fertility issues. Environmental changes linked to climate change—such as rising temperatures, decreasing oxygen levels, and ocean acidification—can also cause genetic female fish to develop as males. Interestingly, fish possess the unique ability to delay their labile period, and some species have two separate windows during which sex differentiation can be influenced by hormones or temperature. Hermaphroditic species retain this capacity throughout adulthood, enabling them to switch sex multiple times in both directions.