Coral reefs are known to undergo phase shift in to macro-algae and they have lost the capacity to remain in or return to a coral-dominated state. This shift will not only affect corals, but the others heavily depend on heterogeneous habitat afforded by corals.
Sallitivu in Panichchankerni, eastern province, is a small island (41328 m2). The Island is surrounded by a ring of coral reef with an elevated breaking reef crest, seaward slope and centred shallow lagoon (<1.2m at high tide). The shore is entirely a thick layer of washed coral rubbles. The archived aerial photographs confirmed these coral rubbles present only after 2004 tsunami.
Underwater visual census were carried out within the reef lagoon and three sites in reef slope using 30 m long belt transect. In addition to diversity of corals and algae, percentages of live, dead and bleached coral cover were recorded.
The reef lagoon is shallow (10-60 cm) and much of the reef crest is exposed at low tide. Within the reef lagoon, the live coral cover was <5%. Around 15 % was observed recently bleached, 12 % were overgrown by algae; Padina sp, Halimeda sp, Sargassum sp, Caulerpa recemosa and Dictyota sp, and the rest was dead corals smothered by sediments. The seaward slope with high wave action was mostly smothered dead corals with live corals <3 %. Coral colonies were represented by Acroporidae (branching and table corals) - Acropora cytherea, A. divaricata, A. formosa, A. gemmifera, A. grandis, A. hemprichii, A. hyacinthus, A. latistella, Acropora sp., A. nobilis, and A. robusta; (Foliaceous)- Montipora aequituberculata and M. hispida; Faviidae (sub massive and encrusting) - Favites halicora, Favites spinosa, Leptastrea purpurea and Platygyra daedalea; Pocilloporidae (Lace /cauliflower) -Pocillopora damicornis; Poritidae (Massive /submassive)- Porites evermanni, P. paliformis, and P. rus.
Live corals observed were immature. Southern end of the reef slope had emerging corals among unstable coral rubbles. It is assumed that the degradation was started post-tsunami and continued due to natural stresses. The recovery of corals may hindered by macro-algal growth and resulting accumulation of sediments, smothering due to less wave action within reef lagoon and resulting recruitment and settlement failure. Recent bleaching would be due to exposure to direct sunlight during the change of tides and low sea level. Increasing oxygen level due to algal blooms would also prone for bleaching.
Avoiding such undesirable phase shifts from coral dominance to algae and reverse them when occur, requires an urgent reform of scientific approaches to understand the processes causing the degradation. A better understanding on why some reefs rapidly degrade and others do not is critical. Most reef conservation efforts are directed toward reserve implementation, but new approaches are needed to sustain ecosystem function since demarcation of a marine reserve alone would not benefit in improving reef resilience.
Biofouling is one of the major means of introducing organisms in to new marine environments. Bryozoans form the major component of the biofouling community. There is dearth of information on their presence in our waters. Therefore, systematic description on existing biofouling species in Sri Lankan coastal region is very essential. This paper describes the composition of bryozoans of the class Gymnolaemata with a description of two new species recorded from coastal waters of Sri Lanka.
The study was conducted in Colombo Port, one of the busiest ports in the country as well as in the region with an increased vulnerability for the introduction of geographically distinct species along with increased shipping operations. Monthly samples were collected from eight sampling stations using artificial settlement collectors which consisted of rope backbone supporting a number of horizontal PVC pipe arms that were attached to the settlement surfaces. The collectors were submerged systematically where first level was 1m below the water surface and others setting at 1m intervals. Species were identified microscopically observing fine morphological features. Scoring percentage covered by each bryozoan was determined using a quadrat (400 squares each with 5mm x 5mm area).
During the study, seven species of the class Gymnolaemata were recorded namely; Electra bengalensis, Hippoprina indica, Celleporaria volsella, Parasmittina sp., Schiporella errata, Watersipora subtorquata and Sinoflustra annae. According to the One way ANOVA test there is a significant difference (p<0.05) between each sampling location for species richness and total percentage cover. However, there was no significant difference (p>0.05) between four sampling depths for species richness and total percentage cover.
Two new bryozoans identified were, Sinoflustra annae and Electra bengalensis. Percentage cover of S. annae and E. bengalensis ranged from 1-18 % and 0.3-40 % respectively. Among these, E. bengalensis was recorded in all sampling stations yet S. annae was recorded only in CICT, BQ, OP and UCT. Though, these species are native to India there are no published literatures for the presence of Sri Lankan coastal waters. Therefore, present finding will be the first record for their presence in Sri Lanka.
Key Words: Bryozoans, species richness, percentage cover, Colombo Port, Sinoflustra annae, Electra bengalensis
Invasive species recognized as one of the greatest threats to global biodiversity and biofouling on submerged structures within a port environments is one the major pathways of invasions by Non Indigenous Species (NIS). Early detection and monitoring of such deleterious organisms since control in nearly impossible once established.
The present work is a baseline study for biofouling faunal assemblage in Hambantota Port. The study consisted of two stages; initial sampling for investigating existing biofouling assemblage and review sampling after 10 months in order to monitor the changes in community structure. Sampling followed an international protocol developed by Center for Research on Introduced Marine Pest (CRIMP).
Samples were scraped from submerged hard substrata in 12 sampling sites with the assistance from divers. Organisms in scraped samples were identified to the nearest taxonomic level using taxonomic guides and databases. All together 90 species were recorded during the study. Among them, 72 species were recorded within the baseline sampling and additional 18 during review sampling. Highest number of species recorded from phylum Mollusca (54) followed by Arthropoda (11), Annelida (11), Chordata (5), Cnidaria (4) and Echinodermata (3) and Bryozoa (2).
Balanus amphitrite, Balanus tintinnabulum, were the most common species in baseline sampling while Chthamalus sp.1 and Cellana radiata in the review sampling. Balanus tintinnabulum, Clypidina notata, Cellana radiata, Thais echinata, Harmoniconus parvatus and Saccostrea cucullata were the most common species found in both sampling.
In baseline sampling highest number of species was recorded from Oil Pier (31) while least number (1) was recorded in the Outer Harbour Artificial Island. In review sampling highest species richness (12) recorded in West Bank while least species richness (5) was recorded within the West Breakwater.
The most noteworthy finding is that eight globally known invasive species which include, Rapana venosa, Phallusia nigra, Perna perna, Brachidontes pharaonis, Balanus amphitrite, Balanus reticulates, Balanus trigonus and, Schizoporella errata were recorded. Among them Rapana venosa was recorded only in review sampling and rest in baseline sampling.
Key words: Biofouling, Non-Indigenous species, Baseline study, Hambantota Port