Recruitment of biofouling communities in the coral reefs of Hengam Island (Persian Gulf): The interaction of nutrients and grazing

Abstract

Introduction: The coverage of Persian Gulf coral reefs has decreased in recent years due to
global scale stressors such as global warming and acidification of oceans and local stressors
such as ecotourism and coral diseases. This condition is often associated with the overgrowth
of algae and other benthos and impairs the ability of coral communities to regenerate. However,
the evidence suggests that coral reefs can essentially be recovered in the absence of stressors
and destructive agents, provided that the larvae settle properly on the bed and among biofouling
organisms competitors. Therefore, studying the interaction of nutrients and grazing as a
precondition for coral larvae settlement is very important in determining the health of coral reefs
and benthic population structure in management discussions.
Materials & Methods: In order to determine the relative importance of nutrient and grazing on
the settlement pattern of hermatypic corals and other epibenthic communities in the coral reefs
of Hengam Island, experimental manipulations was designed and performed in four treatments
in terms of nutrient s and grazing parameters. The beginning of this research was from autumn
1398 to the end of summer 1400 in four time periods of spring, summer, autumn and one
year-period-panel on ceramic panels with a size of 20×20 cm for 21 months.
Results: The statistical results show the predominant effect of the nutrient parameter in
controlling the subsidence of benthic communities compared to the grazing parameter in coral
ecosystems of Hengam Island. This reflects the fact that the studied coral ecosystems of Hengam
Island are mainly driven by a "bottom-up control" mechanism.
Conclusion: According to the present study, it can be concluded that if by adjusting the global
and local stressful conditions, the coral reefs of Hengam Island are in the direction of
regeneration and restoration, the intensity of grazing in the case of s high levels of nutrients will
not be able to remove algal biomass and competing biofoulings, and coral larvae will not be
able to settle and spend post-settlement phase successfully.