[Coral-List] "The coral-eating sponge"

[Charles Birkeland]

 -  -  -  <!--  /* Font Definitions */  @font-face 	{font-family:"Cambria Math"; 	panose-1:2 4 5 3 5 4 6 3 2 4; 	mso-font-charset:0; 	mso-generic-font-family:roman; 	mso-font-pitch:variable; 	mso-font-signature:-1610611985 1107304683 0 0 159 0;} @font-face 	{font-family:Calibri; 	panose-1:2 15 5 2 2 2 4 3 2 4; 	mso-font-charset:0; 	mso-generic-font-family:swiss; 	mso-font-pitch:variable; 	mso-font-signature:-1610611985 1073750139 0 0 159 0;}  /* Style Definitions */  p.MsoNormal, li.MsoNormal, div.MsoNormal 	{mso-style-unhide:no; 	mso-style-qformat:yes; 	mso-style-parent:""; 	margin-top:0in; 	margin-right:0in; 	margin-bottom:10.0pt; 	margin-left:0in; 	line-height:115%; 	mso-pagination:widow-orphan; 	font-size:11.0pt; 	font-family:"Calibri","sans-serif"; 	mso-fareast-font-family:Calibri; 	mso-bidi-font-family:"Times New Roman";} .MsoChpDefault 	{mso-style-type:export-only; 	mso-default-props:yes; 	font-size:10.0pt; 	mso-ansi-font-size:10.0pt; 	mso-bidi-font-size:10.0pt; 	mso-ascii-font-family:Calibri; 	mso-fareast-font-family:Calibri; 	mso-hansi-font-family:Calibri;} @page Section1 	{size:8.5in 11.0in; 	margin:1.0in 1.0in 1.0in 1.0in; 	mso-header-margin:.5in; 	mso-footer-margin:.5in; 	mso-paper-source:0;} div.Section1 	{page:Section1;} -->   Dear Coral-listers,
  The recent blogs on Terpios and competition among sessile organisms bring recollections of an interesting sequence of student projects with Terpios decades ago. There was a dramatic increase in abundance of Terpios hoshinota (then known as Terpois  n. sp.) in the early 1970s. It was found on all sides of Guam and, in one case, covered most of one section of reef terrace nearly a kilometer in length.  It was also found throughout Micronesia (Palau, Yap, Chuuk (then Truk), Saipan, Rota, Aguijan, Pagan) and elsewhere in the western Pacific (Cebu Island, Philippines, and Taiwan, Dick Randall, pers. comm.), Okinawa (Masashi Yamaguchi, pers. comm.) and Indian Ocean (Hansa Chansang, pers. comm. )  From 1971 – 1973, Pat Bryan (1973) studied its distribution and growth and found that it would readily grow over most hard substrata (but not sand), and it would grow 4 times as fast on living coral (6.5 mm +/- 2.2 SE) per 8 days as compared to bare reef substratum (1.4 +/- 0.9). This observation, he reasonably conjectured, might “imply that the sponge is nutritionally benefitting from the coral”.
  So for a few years, Terpios was hypothesized to be possibly a “coral-eating sponge”. To test this, Gyongi Plucer-Rosario (1987) did some field experiments with Terpios and found that although Terpios grew faster over coral than over bare reef rock, it would grow even faster over cleaned reef rock and plexiglass. She concluded that bare reef rock is not really bare, but covered with nasties like hydroids and microbes that can inhibit Terpios growth.  Really bare substrata such as plexiglass and cleaned reef rock were even better than living coral as a raceway for Terpios. “Coral-eating sponge” was a headline to get your attention, but not truth in advertising. It worked.
  Sometimes the space occupied by Terpios was overgrown by corals such as Porites rus and Montipora sp. and by calcareous algae.  Likewise, in American Samoa, corals can be seen to overgrow CCA, but CCA is also frequently seen to overgrow living Acropora and corals of other genera.  Direction of competitive advantage often seems to benefit from angle of initial encounter.
  Terpios is usually not found in the shade on the undersides of corals or in crevices. Similar to another sponge with cyanobacteria, Dysidea herbacea, and with corallimorpharians and didemnid ascidians with photosynthetic microbes, Terpios hoshinota seems to have a tendency to be especially common in clear water and somewhat protected from wave energy, often very far from concentrations of humans. In Palau, Terpios was apparently most common on the inside of Kossol Reef, the large lagoon north of Babeldaob, away from people. In Guam, Terpios was especially common in the lee to the south of Cocos Island, also away from concentrations of humans.  I am certainly not implying that they require being away from people, but I doubt these autotrophic holobionts require disturbances from humans to grow into extensive large-scale patches. The distribution of Terpios on Guam in 1971-1973 seemed somewhat complementary, not sequential, to outbreaks of COTS (Bryan 1973). As said by Thomas Le Berre, Terpios seems to do best where corals are doing well or recovering.
  Chuck
  Bryan, P.G.  1973. Growth rate, toxicity, and distribution of the encrusting sponge Terpios sp. (Hadromerida: Suberitidae) in Guam, Mariana Islands. Micronesica 9: 237-242
  Plucer-Rosario, G. 1987. The effect of substratum on the growth of Terpios, an encrusting sponge which kills corals. Coral Reefs 5: 197-200
  

 Charles Birkeland
Hawaii Cooperative Fishery Research Unit
Department of Zoology
2538 The Mall, Edmondson 164
University of Hawaii 
Honolulu, HI 96822
(808) 956-8678
FAX (808) 956-4238