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In order to improve understanding of the larval migration and early life history characteristics of 4 tropical eels, Anguilla marmorata, A. bicolor pacifica, A. celebesensis and A. borneensis, the leptocephali, metamorphosing leptocephali and oceanic glass eels collected during 8 cruises in the western Pacific and Indonesian Seas from 1991 to 2002 were analyzed. The leptocephali of A. celebesensis and A. borneensis were collected only in close proximity to their relatively small species ranges in the Indonesian Archipelago and were found to have faster growth than the other 2 species with small-scale local migrations. The more widely distributed species A. marmorata and A. bicolor pacifica were collected in most sampling areas. Small leptocephali of A. marmorata were collected only to the west of the Mariana Islands, and only larger specimens, metamorphosing leptocephali, or oceanic glass eels of both species were collected in the Indonesian Seas. These distributions suggested that the 2 species have intermediate-scale migrations compared to other anguillid eels. The leptocephali of all 4 species appeared to reach a fully grown size of around 50 mm, which is considerably smaller than the maximum size of temperate anguillid leptocephali, and their growth was predominantly faster than that of temperate species. These data and recently derived molecular phylogenetic relationships among all anguillid species in the world suggest that the long spawning migrations of temperate eels evolved from much shorter migrations of tropical species, whose larval growth was faster and whose maximum larval sizes were smaller. KEY WORDS: Leptocephalus · Eel · Otolith · Growth · Metamorphosis · Migration Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 309: [233][234][235][236][237][238][239][240][241][242][243][244][245][246] 2006 rent (NEC) from west of the Mariana Islands in the western North Pacific (WNP) to its recruitment areas in East Asia (Tsukamoto 1992). A similar spawning area in the South Equatorial Current (SEC) also appears to be used by A. australis from Australia and New Zealand (Jellyman 1987, Aoyama et al. 1999. Therefore, most temperate anguillids appear to have very similar large-scale migrations and spawn in areas that enable their leptocephali to use low-latitude westward-flowing currents such as the NEC and SEC to transport them thousands of kilometers back to their juvenile growth habitats .Recently, however, it has been shown that some tropical anguillid eels have much shorter local migrations and spawn over the deep waters adjacent to their freshwater growth habitats in the Indonesian Seas (Aoyama et al. 2003). The presence of small leptocephali of Anguilla celebesensis and A. borneensis near Sulawesi Island of central Indonesia indicated that these tropical eels do not migrate very far to spawn, because they have relatively small species ranges, with A. celebesensis being found from Sulawesi Island north through the Philippines and east to western...

The objective of this research was to evaluate the accuracy of random forest classification rule using object based image analysis (OBIA) application (eCognition Developer) and the results were compared with common pixel-based classification algorithm (maximum likelihood/ML) for mangrove land cover mapping in Kembung River, Bengkalis Island, Indonesia. Seven data input model derived from Landsat 5TM bands, ALOS PALSAR FBD, and spectral transformations (NDVI, NDWI, NDBI) were examined by both classifiers. Feature objects statistical parameters were selected and implemented on random forest classifier. Overall accuracy (OA) as well as user and producer accuracies and Kappa statistic were used to compare classification results. Our results showed that the more data model used produced higher overall accuracy and kappa statistics for RF classifier. For each data input model, random forest classifier has higher overall accuracy than maximum likelihood. The best mangrove discrimination in RF classifier was achieved when the combination of Landsat 5 TM, SAR, and spectral transformation were used, while in ML classifier, the best mangrove discrimination was achieved when the combination of Landsat 5 TM and ALOS PALSAR was used. The overall accuracy achieved by RF classifier was 81.1% and 0.76 for Kappa statistic. Meanwhile, for ML classifier, the overall accuracy achieved was 77.7% and 0.71 for Kappa statistic.

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A research cruise was conducted in the eastern Indian Ocean off west Sumatra, Indonesia, in June 2003 to learn about the spawning and larval ecology of the tropical freshwater eels of the genus Anguilla in the region. A total of 43 anguillid leptocephali were collected during the cruise and they were genetically identified as 41 Anguilla bicolor bicolor, 1 Anguilla marmorata, and 1 Anguilla interioris. A. bicolor bicolor leptocephali were 44.1-55.5 mm TL and most of them were at the fully grown stage. Reexamination of the historical data of Jespersen (1942) also suggested a relatively low abundance of small size leptocephali (<40 mm) of this species off west Sumatra. Although the study area has long been considered to be a spawning site of A. bicolor bicolor, the distributions of leptocephali from the two surveys and the patterns of ocean currents in the region suggest the possibility that the main spawning area of this species is located farther offshore.

Remarkably little is known about the life histories of the many tropical anguillid eels distributed across the Indo-Pacific region, and since the Danish expedition to study eels in the region in 1928 and 1929, research on these eels has only begun again in recent years. Sampling for anguillid leptocephali in the Indonesian Seas has been carried out recently to learn about the spawning ecology and larval distributions of tropical eels there. The leptocephali of Anguilla marmorata, Anguilla bicolor pacifica, Anguilla borneensis, Anguilla interioris, and Anguilla celebesensis were collected around Sulawesi Island both in May 2001 and October of 2002. The development of genetic identification techniques has enabled these leptocephali to be identified to species, and their distributions and sizes during different seasons indicated that there are differing life history patterns among sympatric species in the region. A. celebesensis was found to have been spawning in Tomini Bay of northeastern Sulawesi Island in March and April 2001, but apparently, no spawning had occurred in the late summer and fall of 2002. Studies on anguillid glass eels have suggested that tropical anguillids may spawn throughout much of year, but our research on leptocephali in Tomini Bay and data on the downstream migration of tropical anguillids in the major tributary to Tomini Bay indicate that A. celebesensis may have a distinct seasonal pattern of spawning possibly related to the regional monsoon cycles. This is the first evidence of seasonality of spawning in tropical anguillid eels whose life histories are only just beginning to be revealed.

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The occurrence of phytoplankton blooms in Jakarta Bay has increased significantly, and resulted in, the mass mortality of fish and other organisms. Phytoplankton bloom events are indicated by a change in the color of the sea's surface. Generally, phytoplankton growth is influenced by the levels of nutrients in the water, while spatial distribution is influenced by the pattern of the current. In connection with this phenomenon, research was conducted in 2010, 2011 and 2013, to determine the abundance and distribution of phytoplankton and their connection with the N/P ratio. The results showed that the abundance of phytoplankton ranged from 40x10 6 cells/m 3 up to 1699.1x10 6 cells/m 3 , with the highest recorded data was during the east monsoon in 2010 and the lowest during the first transition period of 2011. The predominant phytoplanktons were frequently diatoms such as Skeletonema, Chaetoceros and Thalassiosira. The distribution of phytoplankton seemingly follows the nutrient concentration ratio where phosphate acted as the limiting factor and nitrogen as the triggering factor. The higher the N/P ratio, the more potentially uncontrolled growth of phytoplankton occurred. When the availability of nutrients increased an increase in total algal biomass occurred, however, the alteration in nutrient composition led to a change in composition of community.