Category Archives: Volume 16 No. 1 (1994) (Special Issue on Tropical Ecology)

A review of new species records from Leyte Island, Philippines


Author: Ma. Juliet C. Ceniza

Abstract

The island of Leyte is located on the southern part of the Visayan-island group which lies between 124°17’ and 124°98; east longitude and between 90°55′ and 11°48′ latitude. From among the Visayan island group. Leyte is rather obscure biologically (Rams 1985). The insect fauna, for example, remains highly insufficiently known as yet (Medvedev 1995). But some records have indicated evidence of unquestionable biological species diversity in the island. Many foreign and local experts have discovered new species and added new records in the island. This section aims to review and put together records of new species which have been published in scattered journals and publications worldwide.

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Leaf litter decomposition in different aquatic habitats


Author(s): Josefo B. Tuyor, Josef Margraf and Paciencia P. Milan

Abstract

Decomposition rates of leaf litter in different aquatic ecosystems were compared. Fifty grams of dried talisay (Terminalia catappa L.) leaves placed in small leaf litter bags were used. These were submerged in a river, an estuary and in the sea at ViSCA, Baybay, Leyte, Philippines.
The highest decomposition rate was recorded in the brackish estuary, with more than 50 percent of the leaf litter processed in a period of 30 days. This might be due to the effects of higher temperature and higher nutrient contents in this site which resulted in higher population densities and activities of the decomposing organisms. Another factor would be the high population density of benthic invertebrates registered in this site.
The decomposition rate in the sea was lowest and reached only less than half of the efficiency of the brackish water environment.

Keywords : Decomposition, river, estuary, brackish, Philippines

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Macroinvertebrate patterns of two Thai Streams


Author(s): Josefo B. Tuyor

Abstract

From March to October. 1993. macroinvertebrate drift patterns in the disturbed stream in Ban Nong Hoi (BNH) and the relatively pristine stream in Doi Chang Kian (DCK), Chiang Mai, Thailand were compared.
Results show that day-night changes in drift were mainly controlled by light rather than water temperature. Maximum drift was recorded soon after dusk and night drift was generally higher than the day drift.
Bactidae. Chironomidae, Hydropsychidae and Lepidostomatidac accounted for high drift number at night while Simuliidae was found to be day-active.Monthly invertebrate drift was primarily influenced by benthos density and flow regime of the streams. The highest drift was recorded in March which coincided with the highest population density of the ben thos, and the lowest at the peak of the rainy season when the flow regime of the streams was very high.

Keywords : Macroinvertebrate, drift, strewn, Thailand

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Spot assessment of the marine invertebrate resources of Baybay waters


Author(s): Bernardita P. Germano and Gloriosa C. Guinocor

Abstract

The marine macrobenthic invertebrate resources of Baybay were assessed using the transect. quadrat method. Two samplings in 23 stations over an area of 2300 m2 yielded a mean macroinvertebrate density of 117 individuals/100m2 . A total of 142 invertebrate species belonging to 72 families in 16 classes in 7 phyla were identified. The three most dominant species are the barnacle Balanus sp. and the gastropods Nerita odonta and Clypeamorus bifasciata bifasciata. Gastropoda is the most dominant and most ubiquitous taxon. The commercially important genera Haliotis and Tridacna arc also found in the area.
Highest and lowest mean density were observed in Bunga and Kilim, respectively. Species diversity was highest in Plaridel and lowest in San Agustin. The mean species diversity of Baybay is lower than of the neighboring Cuatro Islas and camotes Islands.
Siltation appears to be a major macroinvertebrate density-controlling factor in Baybay waters. Thus, vigilance against slash-and-burn agriculture and the removal of rocks and boulders from major rivers should be increased. The pattern of diversity is probably imposed by bottom topography and the practice of beach seining.
The trial mariculture of Haliotis and Tridacna in the southern stations is recommended to possibly increase local seed stocks of these species and introduce a potential source of alternative livelihood for small-scale fishermen. Further, it is recommended that some portion on beach-seined areas (stations from Baybay wharf to Marcos) be reserved for rehabilitation of vegetation so as to have a source of recruits for the exploited sites.

Keywords : Marine invertebrates. Baybay waters, density. species diversity, siltation. Latta topography. beach seining

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Spot assessment of the coral resources of Baybay waters


Author: Bernardita P. Germano

Abstract

The coral resources of Baybay were assessed using the transect-quadrat method. Two samplings in 14 stations over an area of 1400 m2 yielded a mean coral cover of 59.1%. Fifty-four species belonging to 21 genera in 13 families of scleractinian and nonscleractinian corals were identified.
Based on relative cover, the three most dominant species are Acropora hebes, Porites tenuis and A. granulosa. The most ubiquitous of the dominant species are P. lutea, followed by Pocillopora damicornis, A. squarrosa and Seriatopora angulata. Coral cover was highest in Palhi (Tomakin reef) followed by Plaridel, and lowest in Maybog, ViSCA and Maslog. Species diversity was highest in Plaridel and Palhi, and zero in Vi SCA and Mas log. In general, southern stations have better coral cover and diversity than northern stations. The major factors limiting the distribution of corals in the area are apparently depth and substratum. To improve the cover and diversity of corals in Baybay, coral transplantation is recommended in the available continental shelves of the northern stations, with Plaridel and Palhi serving as the source of materials. Criteria for site selection are discussed. Introduction of rocks and boulders and planting of mangrove or beach trees and seagrasses in coral transplantation sites are also recommended to improve larval survival and coral colonization. Vigilance against dynamite fishing and slash-and-burn agriculture should also be maintained.

Keywords : Corals, Baybay waters, coral cover, species diversity, depth. substratum, coral transplantation.

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Seaweed farming in the Philippines


Author: Patria Rosales-Apao

Abstract

The culture methods of the most economically important seaweeds in the Philippines farmed on a commercial basis such as Eucheuma, Gracilaria and Caulerpa are discussed. Culture methods for each species differ depending on the biology and ecophysiological requirements. Problems associated with seaweed fanning include natural causes such as typhoons, aging effect or senescence, diseases and grazing. Seaweed farming has greatly contributed to the socio-economic profile of the farmers and to the protection of the environment although long term changes in natural communities related to the introduction of pure algal stand are expected. More research on cultivars which are disease-resistant and have broader tolerance to environmental conditions in addition to new technology on seed stock production for mariculture in the Philippines are needed.

Keywords : Eucheuma, Gracilaria, Caulerpa, polyculture, ecophysiological requirements

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Seagrass beds of the Philippines


Author(s): Hilconida P. Calumpong1 and Ernani G. Meñez2

Abstract

Seagrass beds are widespread in Philippine nearshore areas. They are productive, hence, much fishing and gleaning occur. For Enaalus acoroides, growth was reported to reach 2 cm d’i and primary production to 0.92 g C m-2 d1 t. A total of 13 species was recorded. Thalassia hemprichii is the most widely distributed and Halophila beccarii is endangered. The Philippine seagrass flora is closely related to the Indo-West Pacific. They form either monospecific stands or meadows of two major associations: Syringodium-Cymodocea-Halodule in sandy substrates, Enhalus-Thalassia in muddy substrates. Majority of the Philippine species flower during the warm months. The major contribution of seagrasses is organic matter in the form of leaf litter (average of 0.5 gdwm-2 tidal cycle-1). As in other ecosystems, seagrass beds suffer from natural and human-induced stresses. Seagrass transplantation was explored as a possible mitigating intervention. Research is still lacking in terms of management strategies and the biology of certain species, including a study of obligate inhabitants of seagrass beds.

Keywords : Seagrass, Philippines, ecology, biology, management

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