Entocladia endozoica sp. nov., a pathogenic chlorophyte: Structure, life history, physiology, and effect on its coral host

Goldberg, Walter; Makemson, John; Colley, S.

A new species of the marine microalgal genus Entocladia is described from its natural habitat, the skeleton of a gorgonian coral (Pseudoplexaura spp.). Host coral tissue forms a tumor capsule to surround the algae. One third of colonies examined from Soldier Key to the Dry Tortugas were found to bear these nodules. Authors abstract: A new species of the marine microalgal genus Entocladia (Ulvellacea, Chlorophyta) is described from cultured material and from its natural habitat, the skeleton of a gorgonian coral (Pseudoplexaura spp.). Host tissues react to the presesence of this filamentous chlorophyte by producing a capsule composed primarily of scleroprotein skeleton, and secondarily of calcareous specules. The skeletal capsule separates the algae from contact with host tissue but in doing so the skeleton loses more than 60 percent of its tensile strength and over 90 percent of its elasticity. The coral colony readily breaks apart at the site of the weakened skeleton, exposing the contained algal filaments to relatively high light fields and sea water, an amino acid-depleted environment. These conditions lead to rapid cytological changes that convert the alga to a reproductive state. Regeneration of damaged host tissue re-seals the capsule and causes resumption of the vegetative condition typical of the enclosed algae. Experiments with native and sultured material suggest that host-derived amino acids, especially tyrosin and cystine, play a key role in regulating the reproductive condition of Entocladia filaments.

Entocladia endozoica sp. nov., a pathogenic chlorophyte: Structure, life history, physiology, and effect on its coral host

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