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Water Quality Impact Christmas Tree Worms (Spirobranchus spp.) Distribution and Community Structure on Hard Corals At Sempu Island Nature Reserve, Malang, Indonesia

100%

Isdianto A. , Amanda S. S. , Yamindago A. , Dewi C. S. U. , Aliviyanti D. , Luthfi O. M. , Fathah A. L. , Atikawati D. , Putri B. M. , Puspitasari I. D.

Journal of Ecological Engineering

2024

tom Vol. 25, nr 5

175--186

The Christmas tree worm (Spirobranchus spp.) is a biota that lives in association with hermatypic corals. This bioeroder damages the structural integrity of corals, making them susceptible to breakage. Therefore, further investigation is required to determine the distribution, diversity, uniformity, and predominance of CTW on hard corals in the Sempu Island Nature Reserve’s waters. The method used is the belt transect method, which refers to the reef check. CTW species will be identified based on their operculum, and corals will be identified based on their growth form, genus, and species. The data gathered were processed, and the abundance value and ecological index were obtained. The CTW species found at the five stations were Spirobranchus gardineri, Spirobranchus cruciger, and Spirobranchus spp., associated with massive corals of the genus Porites and genus Goniastrea. Water quality factors such as currents, sedimentation, and nitrates affect CTW’s presence. Medium-to-fast currents circulate around Sempu Island, where high sedimentation rates of 73.73 mg/ cm2/day decrease light penetration into the waterways. Additionally, elevated nitrate levels contribute to the growth of CTW operculum-covering turf algae. CTW abundance values ranged from 0.018 to 0.084 individuals/m2, diversity index (H’) ranged from 0.403 to 0.760 (low), and uniformity index (E) ranged from 0.582 to 0.966 (unstable to stable). The dominance index (C) values ranged from 0.513 to 0.705 (medium). Based on the index value, it was found that the CTW in Sempu Island was in the unstable category, so there was moderate dominance.

Estimation of fat sand rat Psammomys obesus abundance by using surface indices

84%

Fichet-Calvet E. , Jomaa I. , Giraudoux P. , Ashford R. W.

Acta Theriologica

1999

tom 44

nr 4

The fat sand rat Psammomys obesus Cretzschmar, 1828 is an important reservoir host for the human disease, cutaneous leishmaniasis. To develop a method for monitoring changes in the population density of this rodent over large areas, fragments of food, faeces, urine marks, and earth mounds at the burrow entrance were evaluated as indicators of abundance. The results were compared with population density measured simultaneously by trapping. Through the year as a whole, urine marks correlate poorly with abundance, but the three other indicators correlate well. A correlation coefficient of 0.74 is achieved with food fragments and faeces combined. The correlation is best during the wet season and poorer in dry conditions. The value of this indirect population index is discussed in relation to climatic conditions. Details are proposed for the establishment of a monitoring system for P. obesus populations in time and space.