Abiotic factors control sponge ecology in Florida mangroves (Summary)

Abiotic factors control sponge ecology in Florida mangroves

Joseph R. Pawlik*, Steven E. McMurray, Timothy P. Henkel

Introduction	Background (past knowledge)	In the coral reef sponge assemblages, importance of biotic effects was not recognized until fairly recently. Predation on sponges by fishes was initially dismissed as playing an insignificant roleOn reefs; bioticfactors other than predation appear to be less important in structuring the sponge community. And also formangrove fouling communities in general, the conventional view that abiotic factors play a key role in determining distribution and abundance.
	Hypothesis	The author’s hypothesis: If competition excludes reef sponges from mangrove sponge habitats, reef sponges should be able to survive and grow in these habitats in the absence of competition.
	Aim	To test that reef sponges are excluded from mangrove sponge assemblages in coastal mangrove habitats near Key Largo, Florida.
Material and Method	The Sites	The research conducted at mangrove area at site near Key Largo, Florida, in the summer 2005, the authors chose this site because: 1.      supported resident sponge populations on prop roots of the red mangrove, Rhizophora mangle 2.      experienced a cline of tidal flow based on their geography and past observations. And for detailed each sites are: ·         Jewfish Creek (25° 11.083’ N, 80° 23.3’W)is a relatively wide channel that connects Barnes and Blackwater Sound. ·         Shady Creek (25° 7.989’N,80° 25.276’ W) is a narrow mangrove creek thatconnects to Dusenbury Creek and winds through themangroves to a shallow basin where it branches into 2shallower creeks, one of which is Shady Cove. ·         DryRocks Reef (25° 7.850’ N, 80° 17.521’ W), a shallowpatch reef at ~7 m depth with a high diversity of typicalCaribbean coral reef fauna, served as a sponge collection and control site.
	The species/organism	The species were collected for transplantation: Aplysinacauliformis, Amphimedoncompressa, Aplysinafulva, Callyspongiaarmigera, Iotrochotabirotulata, and Niphateserecta) and 3 having a vasiform morphology (Callyspongiavagnalis, Niphates digitalis, and Aplysinaarcheri
	Method	To answer the question for this research, authors applied an assay by observing the growth of coral reef sponges that took at mangrove area, and also in other side, mangrove area were took at coral reef ecosystem by analyzing the growth and changes in mass of sponges in specific time. They observed the condition of the tidal by applying plaster clods to determine tidal flux daily.Andpercent change inmass was compared across sites and tidal regimes using a 2-way ANOVA.
Result		From the assay, shows that: 1.      Least tolerant ofmangrove conditions was Niphateserecta, followed byAplysinacauliformisand Iotrochotabirotulata, withAplysinafulva, Amphimedoncompressa, and Callyspongiaarmigerathe last to succumb, At Dry RocksReef, all species grew with the exception of A. compressa,which neither gained nor lost length. 2.      Forboth rope and vase sponges, there was no evidencethat tissue loss was due to any biotic factor, such aspredation by fishes or invertebrates, or competitionwith other fouling organisms. 3.      There was also no evidenceof sponge-specific pathogenesis, because mangrovesponges on adjacent prop-roots were healthyuntil the last day of the experimental period. The interesting from this research is we can know that mangrove-sponges could survive in the coral reef condition, but the coral reef-sponges did not survive and it will be losing their mass and died after 60 days (lack of  turbulence, high turbidity, effect of freshwater input and so on).
Discussion		In the present study, none of the 9 species of common reef sponges from Dry Rocks Reef survived transplantation to prop roots at mangrove sponge habitat sites, and most were dead within 60 d. Clearly, if these reef species cannot survive in these mangrove sponge habitats, they could not compete for space with existing mangrove sponges, in contrast to the recent conclusion that reef sponges are excluded from mangrovesponge assemblages by competition. While abiotic factors predominate in determining the large-scale distribution of sponge assemblages among Caribbean mangrove habitats, biotic factors likely dominate at smaller scales, particularly at the level of individual prop roots. Ultimately, of course, sponge distribution and abundance is tied to a shifting spectrum of abiotic and biotic factors, including water quality, currents, storms, food availability, sunlight, predation, competition, recruitment, and pathogenesis, which varies from mangrove, lagoon and grass bedhabitats to patch, barrier, and deep-water reefs.