Is the change in biodiversity of macro-algae in Alexandria coastal waters related to climate change?

Abstract

Over the past fifty years, the warming hypothesis of Mediterranean waters has been supported by a series of physical and ecological observations. In order to study the potential role of climate change on the distribution and composition of the macroalgae and its associated epiphytic microalgae, a total number of 61 water temperature, salinity, macro-algal samples were collected from Abu Qir area during the period from June 2005 to December 2007. A 22-year series of sea surface temperature (SST) at Abu Qir Coast (AQ) in Alexandria; from 1985 to 2007 showed a pronounced increase of SST during this period. There was a pronounced change during the last decade with evidence for a stepwise increase in 1994. The maximum SST reached 30˚C compared to 28.1˚C before 1994. On the other hand, the minimum in SST increased since 2005 from 14.3˚C (1985-1994) to 16.9˚C (2006). The most alterations occurred during the winter months with differences of 2.6˚C. Also along with less change during the summer months reached 1.9˚C. In parallel, long term changes in the algal community structure appear to have taken place during the last 60 years; there is a remarkable decrease in the number of species of macroalgae from 1948 to 2007. The effect of global warming on benthic macroalgae in the AQ area seems to be a decrease in species richness, disappearance of large, canopy-forming species, and disturbed seasonality.