PERKEMBANGAN STRUKTUR KOMUNITAS IKAN KARANG DI PERAIRAN KARANG TAMAN NASIONAL KEPULAUAN WAKTOBI

Wilayah Taman Nasional Kepulauan Wakatobi (TNKW) telah dikenal sebagai perairan yang terkelola dengan baik sejak 2010an. Namun dalam perjalanan waktu, aktivitas wisata dan perikanan diasumsikan akan mempengaruhi ekosistem terumbu karang dan mengubah sturktur komunitas ikan karang di kawasan tersebut. Pemantauan perkembangan sumberdaya ikan terumbu karang menjadi suatu pendekatan penting untuk mengetahui adanya perubahan tersebut dari 2015 sampai 2019. Tujuan dari penelitian ini adalah untuk mengidentifikasi perubahan struktur ikan karang di TNKW. Metode yang digunakan adalah sensus visual bawah air pada transek sabuk seluas 350 m2. Unit analisis dalam pemantauan perubahan adalah 7 suku ikan karang karnivora dan herbivora, seperti Serranidae, Lutjanidae, Lethrinidae, Haemulidae, Acanthuridae, Scaridae, Siganidae dan 1 suku obligat karang (Chaetodontidae). Data terkini menunjukkan bahwa terdapat sedikitnya 95 jenis untuk 7 suku ikan karang, dimana pada tahun basis 2015 dijumpai 111 jenis. Kelompok ikan indikator suku Chaetodontidae dijumpai 32 jenis dari semula yang dijumpai 15 jenis. Rata-rata kepadatan ikan target 392 ekor/350 m2. Biomasanya rata-rata 2.224 kg/ha. Kepadatan ikan indikator 294 ekor/350 m2. Jenis-jenis yang mendominasi komunitasnya sejak tahun basis adalah dari suku, Acanthuridae (butana), Scaridae (kakatua) dan Serranidae (kerapu). Jenis koralivora dari suku Chaetodontidae yang mendominasi sejak tahun basis adalah Hemitaurichthys polylepis dan Chaetodon kleinii. Secara umum komunitas ikan karang di perairan Wakatobi berkembang baik dari aspek keragaman, kepadatan dan biomassa ikan karang. The Wakatobi-Archipelago National Park (WANP) has been recognized as good governance management since 2010s. There was asumption that tourism and fishery activities have been going to effluence on reef ecosystems and then altering the reef fish structure communities throughout the times in the area given. Hence, trend assessment for coral reef resources monitoring is an urgent approach to identify the changes of ranging from 2015 to 2019. This study aimed to identify the reef fish structure changes in the area of WANP. An underwater census visual method was used for 350 m2 in area of belt transect. Analysis units used to monitor changes were belong to groups of carnivorous and herbivorous fishes, such as Serranidae, Lutjanidae, Lethrinidae, Haemulidae, Acanthuridae, Scaridae, Siganidae, and belong to coral obligate such as Chaetodontidae.The updating data showed that there were at least 95 species for 7 families of target reef fishes in which before they were pound out 111 species in the basis year of 2015. Meanwhile, indicator fishes of Chaetodontidae were found out 32 species that they before only found out 15 species. The mean of target fish density is 392 individal/350 m2. The mean of their biomassa is 2,224 kg/ha. The indicator fish density was 294 ekor/350 m2. The species dominated their community since the basis year included the families of Acanthuridae (surgionfish), Scaridae (parrotfish) and Serranidae (groupers). Coralivorous species of Chaetodontidae dominated since the basis year, such as: Hemitaurichthys polylepis and Chaetodon kleinii. Generally, the reef fish communities in Wakatobi reef waters get the good trends in regarding to diversity, density and their biomass.

CONDITION AND SPATIAL DISTRIBUTION OF STONY CORAL IN BUNGURAN, SOUTHWEST NATUNA ISLANDS, INDONESIA

Bunguran waters is part of Natuna waters consisting of several small islands located in the southern part of South China Sea, between Sumatera and Kalimantan Island. This paper reported results of a study on spatial distribution and condition of coral reefs and other biota in Bunguran waters,i.e. percentage cover and diversity of coral species. The observation was conducted using line intercept transect (LIT) on eight stations distributed in Salor Island, Sedanau Island, Komang Island, Kumbik Island, Depeh Strait, Sabangmawang Island, Pulau Tiga Village and Tekolampak Cape. The results showed that the reef type of Bunguran were mostly fringing reef dominated by Porites cylindrica, P. lutea and P. rus. Porites spp. were evenly distributed in all location observed. A total of 115 coral species belonging to 16 genera were found and the percentage of living coral cover ranged from 43.20 to 63.53 %. Coral cover reached their maximum at 10–15 meter depth and decreased rapidly coincident with the increasing depth. In general, the condition of coral cover was in “good” category with the average percentage living cover of coral was estimated 51.38%

The dynamics of coral reef benthic and reef fish communities in Batam and Natuna Islands, Indonesia

The dynamics of coral reef benthic and fish communities and their relationship within the Batam and Natuna Islands were investigated in 2004, 2007, 2010 and 2013. Hard coral covers declined at both locations (Batam by 18.69% and Natuna by 16.50%) in 2013, after which a mass bleaching event occurred in 2010. This dramatically affected fish abundance, given that there was a decline of 39.18 individuals per transect in Batam but strangely there was an increase by 47.36 individuals per transect for Natuna. This increase might be related to the isolated location of Natuna, which prevented fishes from migration, especially juveniles. In the same year, the benthic compositions in both locations changed from Acroporidae dominated reefs to become less complex reefs. Following this, the fish composition became less diverse for Batam but in reverse for Natuna. The changes in benthic communities correlate significantly with fish functional group diversity for Batam and the abundance for Natuna. These differences might be related to geographical conditions and human impacts which are different between the locations, such as being surrounded by group of islands or open sea, and fishing activities. The communities are dynamic spatially and temporally as a result of natural conditions of the environment and human activities

Coral reefs next to a major conurbation: a study of temporal change (1985−2011) in coral cover and composition in the reefs of Jakarta, Indonesia

Coral reefs are diverse, ecologically important and globally threatened ecosystems. Numerous studies have reported on the threats to coral reefs, which include both local perturbations, such as pollution and overfishing, and widespread phenomena, such as bleaching. Here, we report on the history of the Jakarta Bay−Thousand Islands reef system from 1985 to 2011. Over this period, we recorded significant shifts in coral generic composition and an overall decline in coral cover with widely different trajectories between in-, mid- and offshore zones. In 1985, coral cover exhibited a clear on-to-offshore gradient with low coral cover inshore (10%), moderate cover midshore (49%) and high cover offshore (74%). The low coral cover inshore contrasts strongly with reports of high coral cover for inshore reefs in 1929. Inshore, coral cover declined from 10% in 1985 to <5% in 1995. The greatest change in coral cover and composition, however, occurred in offshore reefs, where mean cover declined from 74 to <20% between 1985 and 1995. Acropora species were particularly affected and declined from 36 to just 5% cover offshore. Recovery of coral cover occurred offshore between 1995 and 2005. From 2005 to 2011, however, a less severe loss in coral cover was observed. With the exception of inshore reefs, which appear to be on an ongoing trajectory of decline that started before the 1985 surveys, the reefs of the Jakarta Bay−Thousand Islands system have shown a propensity to recover

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First come, first served: possible role for priority effects in marine populations under different degrees of dispersal potential

Aim Studying clearly delineated populations in marine lakes, islands of sea, we investigate the interplay of habitat size, immigration, and priority effects in shaping marine population genetic structure. Location Marine lakes and coastal locations in Indonesia, Palau, Papua New-Guinea and Australia. Taxon Mussels (Mytillidae, Brachidontes spp.) Methods Populations were sampled from four coastal locations and 22 marine lakes of similar age (~8,000 years), yet differing in size (0.04 - 4.7 km2) and degree of connection to the adjacent sea. While some lakes are highly connected, allowing potential influx of larvae from the sea, others have very limited water exchange. We assessed the phylogeographic structure and demographic history using mitochondrial and nuclear DNA sequence data, and combined this with geometric morphometrics. The effects of lake characteristics on population genetic diversity and structure were tested using linear regression and Mantel tests. Results Each lake contained one of six distinct genetic lineages, which were characterized by deep phylogenetic splits and significant morphometric differences. These lineages likely represent separate species. The lineages showed similar demographic patterns, with lakes containing founder populations that rapidly expanded and diverged. Genetic diversity within lake populations was significantly correlated with lake area, but not with physical connection to the adjacent sea. Within lineages that occurred in multiple lakes there was strong population structure (average ΦST 0.65), which did not conform to an isolation-by-distance pattern or to the degree of dispersal potential. Main Conclusions Marine lakes across a gradient of physical isolation show strong population structure and evidence for in situ divergence. We hypothesize that the observed genetic structure is the result of priority effects. In addition, reduction of habitat size appears to reduce genetic diversity, even at very small spatial scales. Our findings are relevant in the context of ongoing alterations to coastal hydrodynamics, which lead to habitat reduction and influence migration among populations at fine spatial scales

Relating variation in species composition to environmental\ud variables: a multi-taxon study in an Indonesian coral reef complex

In order to manage and conserve coral reefs it is essential to understand the factors that structure reef communities. In Indonesia’s Jakarta Bay – Pulau Seribu reef complex, pronounced on-to-offshore variation in a number of variables was observed. Live coral cover, and echinoderm and fish species richness were higher in midshore sites than either in- or offshore sites. Variation in habitat structure, the abiotic environment, distance between sample sites and covariation of these factors separately explained 9.6 to 15.1%of the spatial variation in the composition of corals, echinoderms and fishes. Together, all three components explained > 50%of the variation in composition. This indicates that spatial and environmental factors influence the distribution of species across the study area and have important implications for the large-scale management of this reef ecosystem. Large scale management and protection of these reefs will probably be important because the majority or reefs were in poor to very poor condition as exemplified by low (<25%) coral cover. The coral cover of some inshore reefs was particularly low (< 1%). Inshore coral assemblages tended to be composed of stress-tolerant or specialised pioneers of highly perturbed environments. There were also locally high densities of potentially destructive species such as the sea urchin Diadema setosum. Midshore sites had relatively high coral cover comprising Acropora and Montipora spp. that were rare or absent elsewhere, presumably due to their sensitivity to pollution and mechanical damage. Most of the offshore sites had relatively low live coral cover and were dominated by rapidly growing pioneers or by stress- or –sediment-tolerant species. Spatial variation in the composition of taxa is discussed in the context of past-and-ongoing disturbances, including land-based pollution, coral mining, sedimentation and destructive fishing practices