Seaweeds are important primary producers, and as such contribute significantly to nearshore ecosystems. Studies on the effects of anthropogenic stresses on these organisms have largely been concerned with the vegetative adult stages of the life cycle. Here we review the limited information on the sensitivity of early stages in the life cycle of seaweeds to global change (UV increase; global warming; increased storm frequencies) and pollution (eutrophication, trace metals and oil). Impacts on fertility, substrate attachment, development, photosynthesis, growth and mortality are highlighted. In their natural habitats, early stages are shade-adapted, as they live shel tered under adult canopies and in pores of the substrata. Although some acclimation under increased moderate irradiance is seen, higher solar irradiance, and especially ultraviolet-B, inhibits early development. Global warming may decrease the fertility and shorten the fertile period of some species. With the increasing likelihood of storms associated with global warming, gamete release may be inhibited while scouring by suspended sediments may detach newly settled stages. Succession and local distribution patterns are likely to be affected. Eutrophication can result in accelerated development of the early stages of some algal species but sewage discharges have a negative impact on sperm motility, fertilisation and can cause increased mortality in germlings. Impacts of other, indirect effects of eutrophication, including increased sediment cover of substrata, scouring caused by wind-induced resuspension of sediments, and grazing, are also expected to be negative. Toxic trace metals affect gamete viability, inhibit fertilisation and development, and reduce growth rates. Gametes are particularly susceptible to oil pollution and interactions between hydrocarbons and the adhesive mucus surrounding the embryonic stages seem to inhibit settlement. Recommendations for future studies are provided that are aimed at gaining greater insight into the effects of anthropogenic stress on the weakest links in the development cycle of seaweeds. [KEYWORDS: seaweeds; juvenile stages; stress factors; UV radiation; global warming; eutrophication; trace metal pollution; oil pollution]
Original languageEnglish
JournalJournal of Aquatic Ecosystem Stress Recovery
Journal publication date2000

ID: 246181