ALGAL FLORA IN THE HULA VALLEY—PAST AND PRESENT

Abstract

Lake Agmon, a small shallow water body (area 1.1 km2, mean depth <lm) was created in April 1994 as part of the Hula restoration project in the dried peat-soils of the Hula Valley. Until ca. 50 years ago, this area was covered with swamps, extending to the north of Lake Hula. We followed changes over time in the abundance and species composition of the algal populations in Lake Agmon over the initial 4 years that followed its creation, consolidated the existing information on the algal populations of the extinct Lake Hula, and compared the Lake Agmon algal populations with those reported from Lake Hula and with those present in Lake Rinneret. Altogether, 276 algal species were found in Lake Agmon, including 140 chlorophytes, 48 euglenophytes, 34 cyanophytes, 31 diatoms, 8 cryptophytes, 8 dinoflagellates, and 4 chrysophytes. A comprehensive species list for Lake Hula was also compiled, based on the limited published accounts. The similarities between the past and present algal communities in the Hula Valley were great: most diatom, dinoflagellate, chrysophyte, euglenophyte, and large chlorophyte and cyanophyte genera that are seen today in Lake Agmon were also reported from Lake Hula. However, the Hula list of genera was shorter than the Lake Agmon list in some particular categories. The lack of most of the nannoplanktonic Chlorococcales, and all cryptophytes and other small flagellates from the Hula list was attributed to different sampling and preservation methods in the early days; the absence of most filamentous cyanobacteria is considered a real difference, possibly resulting from the more eutrophic status of Lake Agmon. Notably, the dinoflagellate Peridinium gatunense, which blooms annually in Lake Kinneret downstream of the Hula Valley, was not recorded in Lake Hula and did not occur in Lake Agmon.