An early stage of the disease in Ircinia, with a small patch of disease on the lower left. (E.R. Gammill)
Negelkerken (2000)
described the death and disintegration of a very large
Xestospongia muta in 1997 in Curacao in a period of just 4 months. The symptoms were the same as in Cozumel and elsewhere. We are told that there was a mass die-off of
Xestospongia muta in the Caymans two years ago, with similar symptoms.
Paz (1996)
reported a disease outbreak in Belize in 1996 that had similar symptoms. Sponge diseases have also been reported from Tobago and Panama affecting some of the same sponges. Eric Borneman reports he has seen it in Belize, Aruba, the Texas Flower Gardens
(Borneman, 2004)
and the Florida Keys, and he and Andy Bruckner have seen sponge disease in remote areas of Puerto Rico and Dominica. A colleague in Cuba has photographed the same symptoms in
Xestospongia muta there. Ernesto Weil has been documenting sponge disease in the southern Caribbean as well. Don Behringer reports observing a mass die-off of all
Ircinia strobilina and
Ircinia campana at his study site in Florida Bay in 1999 within about a one-month period. The sponges had a mold-like film on them and disintegrated on touch. Ed Tichnor reports that
Xestospongia muta sponges have been yellowing and disintegrating off Boynton Beach, Palm Beach County, Florida for the last few years.
Calyspongia plicifera, with dead areas on the top edge and on the surface. This sponge will die. (E.R. Gammill)
Joseph Pawlik has reported that in Key Largo, Florida and remote areas of the Bahamas,
Xestospongia muta experiences "cyclic bleaching", that is, bleaching on an annual basis, each fall (there is a similar report in the coral
Favia fragum in Florida).
This does not resemble the disease reported here, though may be occurring widely and could weaken sponge resistance to disease. He also reports another syndrome in
Xestospongia muta there, fatal bleaching or "Sponge Orange Band" (SOB).
This involves an orange band moving across the sponge, leaving white bleached or dead sponge behind. This also appears to be different from the diseases we describe from Cozumel. Orange bands were never observed on sponges in Cozumel.
We think that the "Sponge Orange Band" which Pawlik describes and illustrates on his website appears likely to involve a pathogen as he suggests, not bleaching.
He states that both cyclic and fatal bleaching appear to be Caribbean-wide and present since the late 1980’s. Coral disease frequently involves patches of coral tissue that have lost zooxanthellae and appear white. But the loss of zooxanthellae during coral bleaching is a different phenomenon than mass coral bleaching due to high temperatures. Higher temperatures do increase the incidence of some coral diseases such as black band. Bleaching at high temperatures has been found to be caused by a pathogen in one coral in the Mediterranean. However, this has not been shown to be the case in the vast majority of coral species.
Among other things, at high temperatures all corals bleach, while in coral disease only some of the colonies are affected at a time, and often the disease sweeps across the coral with part of the coral healthy until the disease reaches it, and in some diseases elevated temperatures are not a known requirement. Cyanobacterial symbionts are known from all of our sponge species except
Callyspongia plicifera.
Healthy Verongula gigantea on the right, healthy Niphates digitalis in the middle, and Xestospongia muta showing white spots that indicate disease on the left. (E.R. Gammill)
We think that sponges will be found to have mass bleaching to high temperatures (at least for those with photosynthetic symbionts, as reported in
Fromont & Garson (1999)
, which will be found to be a different type of event from sponge disease, which can also afflict species without photosynthetic symbionts, such as the commercial sponges in which disease is well known. We believe it is worth trying to make this distinction whenever possible. We realize that we are making many untested assertions, and wish to see as many tested as possible and as soon as possible, but feel it is best to alert the scientific and management community quickly and not wait for years for them to be tested.
Wulff (2006)
recently reported on long-term monitoring of sponge populations in Panama. From 1984 to 1998, there was a loss of 43% of sponge volume in the quadrats, and a loss of 51% of the species in those quadrats.
Similar changes were found in more wide-ranging qualitative surveys on 41 other nearby reefs. Massive sponges and kerotose sponges had the greatest declines, while branching sponges did not decline. All species of
Ircinia declined drastically, as did
Verongula and
Callyspongia.
Geodia and
Xestospongia muta were not in the quadrats. Wulff concluded that disease was the most likely cause of the declines, and indeed observed disease in 11 species, including four species of
Ircinia. She points out that sponges are important for a variety of ecosystem functions, and urges monitoring of sponge volume and species.
Declines can easily be missed without quantitative monitoring. We agree with Wulff that disease is the likely culprit, and that monitoring is important.
Webster et al (2002)
reported the first isolation and characterization of a pathogen causing disease in a sponge.
The bacterial pathogen digests the spongin fibers in the skeleton of a sponge on the Great Barrier Reef,
Rhopaloiedes odorabile. The symptoms include initial fouling of the surface of the sponge with epiphytic algae, and the sponge skeleton being soft and fragile once infected.
They state that the symptoms were similar to that in commercial sponges in the Mediterranean (where sponges had fragile and brittle skeletons that crumbled under water), with the bacteria tunneling inside the spongin fibers. They state that the similarity of symptoms and the microscopic evidence between the Australian sponge and the Mediterranean sponges indicate that bacterial sponge disease may be a global phenomenon. The similarity to the weakening and disintegration of the skeleton of
Xestospongia muta (which may in the last stages be held together by a large quantity of spicules), the softening of diseased
Verongula gigantea and the algal epiphytes on
Geodia sp. at an initial stage, suggests that the cause may be bacteria burrowing in skeletal fibers as in the Mediterranean commercial sponges and the Australian sponge.
From these reports, it is clear that this disease(s) have been in the Caribbean since at least 1996, and that sponge disease is widespread in the Caribbean, Gulf of Mexico, and Florida. Since 100% of
Xestospongia muta individuals are now infected in Cozumel, and it is a lethal disease, it is clear that this disease will have a major effect on these species, and will probably have a major effect on the sponge community and reef. The same is likely to happen throughout the Western Atlantic. This may be an epizootic.
We urge people to document the disease on their reefs, include it in monitoring even if not present or rare, and preserve some samples for histology in buffered seawater formalin in generous quantity, and other samples for genetics in ethyl alcohol.
