Analysis of the Density of Sea Cucumbers (Holothurians) based on the Type of Coral Cover in Karimunjawa Waters, Jawa Tengah

Sea cucumber resources is one of the commodities of marine resources is very important and has a highcommercial value. One of the commercial sea cucumber species found in the waters of the Stichopus vastus Karimunjawa (local name: gamets). The high commercial value sea cucumbers cause excessive exploitation of the resources, so that would threaten its sustainability. To preserve water resources in the sea cucumber can be maintained properly required for resource management actions. Aspects of reproduction is one aspect of the basis used to determine the management of aquatic resources in sea cucumbers Karimunjawa, which is associated with survival and breeding. Research purposes (1) to analyze and determine the development level of gonad maturity in the waters of Stichopus vastus Karimunjawa, (2) analyze and know the stage of mature gonads S. vastus monthly in Karimunjawa waters, (3) analyze and determine the condition of mature gonads S. vastus based on length of interval scales in the waters Karimuinjawa, and (4) identify and analyze the gonadal somatic index (GS I) when mature gonads S.vastus in Karimunjawa waters. Sample collection on a monthly basis during the period July 2010 until May 2011, within methods of systematic sampling. Samples were collected from the catch freely on a predetermined location within the boundaries of the study sites. Pickling sea cucumbers sample with 2.5% Mg Cl2 use traditional and gonad used for solution of buffered formalin. During the study found that the mature gonad stage is the stage of development that has the highest percentage compared to the stages of gonad maturity of the other. Every month observation, always get ripe gonad condition, with the percentage varying, so that seasonal patterns are less likely. Obtained information that the S. vastus spawn in the month - the month September- November and March to May, with a length of 269-286 mm size range. Quantitative assessment based on the gonad somatic index (GSI) found that in July and September in a condition to cook, while in other months, namely November, January, March, and May show the condition begins to mature. Keywords : Stichopus vastus, gonad maturity, and gonad somatic index

Sea cucumber is one of the important natural resources of Karimunjawa Islands. Because it has a high economic value, so fishermen exploit excessively it may reduce the population. Naturally sea cucumbers are able to reproduce asexually by fission process (division). This study aimed to determine the ability of fission and regeneration of sea cucumber Holothuria edulis and Holothuria leucospilota having different body sizes. The research was conducted in October-December 2011, in Karimunjawa waters. Jepara. Stimulation of fission carried out by binding sea cucumbers with a rubber band at 1/3 position of the anterior part. The results showed that the sea cucumber H. edulis and H. leucospilota successfully split at the 24. The difference in the size of cucumbers affect the fission time, while the intensity of regeneration of bigger sea cucumbers has higher value than a small one. The rate of fission of H. edulis and H. leucospilota 95-100%. Regeneration intensity of bigger H. edulis and H. leucospilota are higher than the small size. Posterior part of the body has higher survival rate is than the anterior.

The El Niño–Southern Oscillation (ENSO) event induces significant sea-level and temperature changes, which can severely impact the coral reef ecosystem. El Nino has affected Indonesia since June 2023, intensifying from late 2023 through April 2024, and has the potential to cause coral bleaching events. Karimunjawa is a vital marine protected area in the Java Sea, which has high coral diversity and is potentially threatened by mass bleaching. To assess the extent of coral bleaching in Karimunjawa waters, a rapid survey was conducted in early February 2024, focusing on the eastern waters, specifically the east coast of Karimunjawa Island and Tengah Island. The study of a 50 m line transect in different depths was implemented to quantify bleaching colony density and assess the bleaching level. The study revealed a low coral bleaching in Karimunjawa with varying severity, almost one-third of the coral colonies experienced >75% bleaching, and a quarter was found to have bleaching in both levels 50-75% and 25-50%. Coral bleaching densities ranged from 0.58 to 3.42 colonies per square meter, with the highest density in shallow waters, particularly for branching corals. Although coral bleaching in Karimunjawa is relatively low, the high percentage of Acropora corals experiencing bleaching will contribute to the decline in coral cover and diversity in this marine protected area.

Changes in vegetation cover and land use can cause the fragmentation and destruction of ecosystems, resulting in a negative impact on biological diversity. It is likely that it occurred in recent decades in the Selva “El Ocote” Biosphere Reserve, in Chiapas, Mexico. Therefore, the objective of this research project was to determine the rate of change in vegetation and land use for the southern zone of the Selva El Ocote Biosphere Reserve (REBISO) and its adjacent area, for the period 1980-2022. First, a characterization of the types of vegetation and land use was carried out in two polygons (areas) located to the south of REBISO based on Landsat images. Subsequently, a supervised classification was carried out, and finally the rate of change in land use and vegetation was determined based on the rate of change formula described by the FAO. The results obtained show that in the polygon called "General Lázaro Cárdenas", in its section located within the REBISO, it consisted of seven types of vegetation cover and land use, of which were Acahual, Selva Median Subperennifolia, Human Settlements, Roads, Pastures, River and Agricultural Zone; while in its section outside REBISO, six types of cover and land uses were identified: Acahuales, Human Settlements, Roads, Pastures, Medium Subevergreen Forest and Agricultural Zones. On the other hand, for the polygon called "Riviera Piedra Parada", in its section located within REBISO, it was characterized by seven types of vegetation cover and land use, which were: Acahuales, Human Settlements, Roads, Pastures, Low Jungle Deciduous, Water Bodies and Agricultural Zones; while, in its section located outside REBISO, nine types of vegetation cover and land uses were identified: Acahuales, Human Settlements, Roads, Bodies of Water, Sinkhole, Pastures, Low Deciduous Forest and Agricultural Zones. The rate of change in the section located within the REBISO of the "General Lázaro Cárdenas" polygon was characterized by the increase of Acahual, Pastizal and Agricultural Zones, and by the decrease of Selva Mediana from 1984 to 2022. The section of this polygon located outside the REBISO, it was characterized by a decrease in Medium Forest, as well as an increase in Grasslands, Acahual, Roads, Human Settlements and Agricultural Zones in the same period. As for the section located within the REBISO of the "Riviera Piedra Parada" polygon, the rate of change was characterized by the decrease in Low Deciduous Forest and an increase in Acahual, Bodies of water and agricultural areas in the same period, while that the section of this polygon located outside the REBISO, was characterized by the decrease of Acahual, Selva Baja Caducifolia from 1984 to 2022. This information suggests the loss of original plant associations and the increase of anthropogenic land uses inside and outside the REVIEW. This information is important to be able to carry out the update of its Management Plan, and allow the creation of different mechanisms that help the sustainable use of its natural resources, contributing to the conservation of its flora and fauna, and the improvement of quality of life of the communities in the area. Los cambios de cobertura vegetal y de uso de suelo pueden ocasionar la fragmentación y destrucción de ecosistemas, resultando en un impacto sobre la diversidad biológica. Es probable que haya ocurrido en las últimas décadas en la Reserva de la Biosfera Selva “El Ocote”, en Chiapas, México. Por ello, el objetivo de este proyecto de investigación fue determinar la tasa de cambio en la vegetación y uso de suelo para la zona sur de la Reserva de la Biosfera Selva El Ocote (REBISO) y su área adyacente, para el periodo 1984-2022. Primero se llevó a cabo una caracterización de los tipos de vegetación y uso de suelo en dos polígonos (áreas) localizados al sur de la REBISO a partir de imágenes Landsat. Posteriormente se realizó una clasificación supervisada, y finalmente se determinó la tasa de cambio de uso de suelo y vegetación a partir de la fórmula de tasa de cambio descrita por la FAO (1996). Los resultados obtenidos muestran que en el polígono denominado “General Lázaro Cárdenas”, en su sección ubicada dentro de la REBISO, constó de siete tipos de cobertura vegetal y uso de suelo, de los cuales fueron Acahual, Selva Mediana Subperennifolia, Asentamientos Humanos, Caminos, Pastizales, Río y Zona Agrícolas; mientras que en su sección fuera de la REBISO, se identificaron seis tipos de cobertura y usos de suelo: Acahuales, Asentamientos Humanos, Caminos, Pastizales, Selva Mediana Subperennifolia y Zonas Agrícolas. Por otro lado, para el polígono denominado “Riviera Piedra Parada”, en su sección ubicada dentro de la REBISO, se caracterizó por siete tipos de cobertura vegetal y uso de suelo los cuales fueron, Acahuales, Asentamientos Humanos, Caminos, Pastizales, Selva Baja Caducifolia, Cuerpos de Agua y Zonas Agrícolas; mientras que, en su sección ubicada fuera de la REBISO, se identificaron nueve tipos de cobertura vegetal y usos de suelo: Acahuales, Asentamientos Humanos, Caminos, Cuerpos de Agua, Dolina, Pastizales, Selva Baja Caducifolia y Zonas Agrícolas. La Tasa de cambio en la sección localizada dentro de la REBISO del polígono “General Lázaro Cárdenas” se caracterizó por el incremento de Acahual, Pastizal y Zonas Agrícolas, y por la disminución de Selva Mediana desde 1984 hasta el 2022. La sección de este polígono localizada fuera de la REBISO, se caracterizó por una disminución de Selva Mediana, así como por un aumento de Pastizal, Acahual, Caminos, Asentamientos Humanos y de Zonas Agrícolas en el mismo periodo. En cuanto a la sección localizada dentro de la REBISO del polígono “Riviera Piedra Parada”, la tasa de cambio se caracterizó por la disminución de Selva Baja Caducifolia y un aumento de Acahual, Cuerpos de agua y de Zonas agrícolas en el mismo periodo, mientras que la sección de este polígono localizada fuera de la REBISO, se caracterizó por la disminución de Acahual, Selva Baja Caducifolia de 1984 al 2022. Esta información sugiere la pérdida de asociaciones vegetales originales y el aumento de usos de suelo antropogénicos dentro y fuera de la REBISO. Esta información es importante para poder llevar a cabo la actualización de su Plan de Manejo, y permitir la creación de distintos mecanismos que ayuden al aprovechamiento sustentable de sus recursos naturales, contribuyendo a la conservación de su flora y fauna, y al mejoramiento de calidad de vida de las comunidades de la zona.

Sea cucumbers are an economically important fishery commodity in great demand by both local and international audiences. As time goes by, the need for sea cucumbers increases and people make excessive use of sea cucumber resources until they reach the status of over-exploitation. This makes it necessary to know the level of utilization of sea cucumbers in Karimunjawa. This research was carried out on August - September 2023 in Tanjung Gelam, Karimunjawa. The purpose of this research is to find out the catch per unit effort, maximum sustainable potential/maximum sustainable yield, and the level of utilization of sea cucumbers in Karimunjawa waters. This research uses a survey method with the survey carried out to collect data regarding catches and fishing trips for fishermen directly. The data analysis method uses model calculations Schaefer. From the research results, it was found that the average CPUE production value was 4 kg/trip. The potential MSY value obtained is 2.857 kg/year with an optimum effort (f opt) of 620 trips/year. The level of utilization of sea cucumbers has an average value of 93,27% which is categorized as optimum, so there is no need to make additional efforts because the catch is already optimal and if it is added it will cause an excess catch.

Hartati R, Widianingsih, Trianto A, Zainuri M, Ambariyanto. 2017. The abundance of prospective natural food for sea cucumber Holothuria atra at Karimunjawa Island waters, Jepara, Indonesia. Biodiversitas 18: 947-953. Holothuria atra, as one of the most abundant and widely distributed sea cucumber species, is an omnivore, consuming detritus, uneaten food, and algae in the substrate. For sea ranching purpose, the objective of present works was aimed to determine potential food availability for H. atra in Karimunjawa Island of Jepara. Biotic environment factors in proposed location were assessed including seaweed and seagrass associated communities, epiphytes on the seagrass, phyto and zooplankton, benthic organism, microphytobenthic as chlorophyll-a, phaeophytin and chloropigmen as well as sediment characteristics. There were six species seagrasses and 10 species of seaweeds found in Karimunjawa waters, with Enhalus acoroides and Thalassia hemprichii provide shelter and food for H. atra. Algal epiphytes use seagrass leaves and rhizome as substrate and there were 28 genera of them belong to Chrysophyta, Chlorophyta, and Cyanophyta. The variety and abundance of phytoplankton, zooplankton the benthos enrich the location. The chlorophyll-a, phaeophytin and total chloropigment in the sediment of Karimunjawa waters could be representative of microphytobenthos. The substrate of Karimunjawa waters consisted of fine sandy-coarse sediment and the content of organic matter may be important for feeding activity of H. atra.

Indonesia has been supplying the highest diversity of dried sea cucumbers (trepang) to world markets for decades even though species validation on the trepang from any producing areas throughout the country is still needed. Karimunjawa (Islands off north coast of Java) is one of trepang habitats. Several visits from May to November 2009 had been made to collect trepang from the fishers and collectors in that area. Eighteen aspidochirote species were identified, more varied than those reported in 1988 and 1992 although 7 species have no longer been found. Three species among those: Actinopyga banwarthi, Bohadschia subrubra, and Holothuria fuscocinerea have never been reported in Indonesia before, neither on the list of commercial sea cucumbers in Asia nor world trade provided by Choo (2008) and Toral-Grande (2007). These species composition shifts may indicate a threat to species diversity, starting with excessive removal of natural stock. Up to now, 28 species of trepang have been recognized from Karimunjawa waters.

AimHabitat complexity plays an important role in the structure and function of ecosystems worldwide. On coral reefs, habitat complexity influences ecosystem services such as harvestable fish biomass and attenuation of wave energy. Here, we test how three descriptors of surface complexity—rugosity, fractal dimension, and height range—trend with the geological age of reefs (0.2–5.1 million years old), depth (1–25 m), wave exposure (1–306 kW/m), coral cover (0–80%), and three habitat types (aggregated reef, rock and boulder, and pavement).LocationWe surveyed across 234 sites and 4 degrees of latitude in the eight main Hawaiian Islands.Time PeriodApril 2019 – July 2019.Major Taxa StudiedReef building corals.MethodsWe estimate three surface descriptors (rugosity, fractal dimension and height range) using structure‐from‐motion photogrammetry. We evaluate hypothesized relationships between these descriptors and geological reef age, depth, wave exposure, coral cover and reef habitat type using generalized linear models that account for survey design.ResultsThe rugosity of reef habitats decreased with geological reef age; fractal dimension (and coral cover) decreased with wave exposure; and height range decreased with depth. Variations in these patterns were explained by the different habitat types and the way they are formed over time. Nonetheless, the three surface descriptors were geometrically constrained across all habitat types, and so habitats occupied distinctly different regions of habitat complexity space.Main ConclusionsThis study showed how broad environmental characteristics influence the structural complexity of habitats, and therefore geodiversity, which is an important first step toward understanding the communities supported by these habitats and their ecosystem services.

We examined coral reef communities at 11 sites within Mafia Island Marine Park using a point count method for substrate and visually censused belt transects for fish populations. Multivariate ordinations showed that the benthic habitat differed among reefs. The patterns were mainly attributed to variations in depth, hydrodynamics and benthic composition. In total, the substratum was dominated by dead coral (49%) and algae (25%), with a live coral cover of only 14%. Three hundred and ninety-four fish species belonging to 56 families were recorded. According to MDS-ordinations and RELATE procedures, fish assemblage composition varied among sites in concordance with the habitats provided. Sites with highest proportion of dead coral exhibited highest degree of dispersion in the multivariate ordinations of fish assemblages. Stepwise multiple regression was used to determine the proportion of variance among sites which could be explained by depth, exposure, rugosity, substrate diversity, branching substrate, live coral cover, dead coral cover and different types of algae. The results showed that habitat variables explained up to 92% of the variation in species numbers and in total, and taxon-specific, abundance. Live coral cover was the foremost predictor of both numerical and species abundance, as well as of corallivores, invertivores, planktivores and of the families Pomacentridae, Chaetodontidae and Pomacanthidae. Our results suggest that habitat characteristics play a dominant role in determining fish assemblage composition on coral reefs.

To elucidate which environmental factors affect lagoonal‐scale sea cucumber distributions in Ishigaki Island, Okinawa, Japan, intertidal and subtidal areas of three coral reef lagoons were classified into several ground divisions by bottom characteristics, and sea cucumber densities therein were compared with the composition of sediment cover, grain size and organic content, and coverage of macroalgae, seagrass, and massive corals. Holothuria atra, Holothuria leucospilota, Stichopus chloronotus, and Synapta maculata had highest densities in the nearshore areas but were rare in reef flats, probably because of wave disturbance and low areal cover of sand sediment as potential feeding environments. No relationship was observed between sea cucumber densities and sediment organic content or grain size. Thus, even if these sea cucumbers have selectivity for habitats with a high sediment organic content, the effect of such selectivity on the distribution seems to be limited to relatively small areas. The sea cucumber distributions can be classified by bottom sediment/biota composition into bedrock (H. leucospilota), sand (H. atra), and lagoonal types (St. chloronotus and Sy. maculata). These habitat selections were possibly related to various aspects of sea cucumber ecology such as refuge from predators or turbulence, or settlement and nursery place, which have implications for importance of the complexity of lagoonal‐scale topography and sediment/biota conditions for the coexistence of various holothurian species.

Monitoring of reef restoration efforts and artificial reefs (ARs) has typically been limited to coral fragment survival, hampering evaluation of broader objectives such as ecosystem recovery. This study aimed to determine to what extent AR design influences the ecological recovery of restored reefs by monitoring outplanted coral fragments, benthic cover, coral recruitment and fish and invertebrate communities for two years. Four AR designs (16 m2), unrestored controls and natural reef patches as reference (n = 10) were established in Mkwiro, Kenya. ARs consisted either of concrete disks with bottles, layered concrete disks, metal cages or a combination thereof. A mixture of 18 branching coral species (mainly Acropora spp.) was outplanted on ARs at a density of 7 corals m-2. After two years, 60% of all outplanted fragments had survived, already resulting in coral cover on most ARs comparable (though Acropora-dominated) to reference patches. Coral survival differed between ARs, with highest survival on cages due to the absence of crown-of-thorns sea star predation on this design. In total, 32 coral genera recruited on ARs and recruit densities were highest on reference patches, moderate on concrete ARs and low on cages. ARs and reference patches featured nearly twice the fish species richness and around an order of magnitude higher fish abundance and biomass compared to control patches. Fish abundance and biomass strongly correlated with coral cover on ARs. AR, reference and control patches all had distinct fish species compositions, but AR and reference patches were similar in terms of trophic structure of their fish communities. Motile invertebrates including gastropods, sea urchins, sea cucumbers and sea stars were present at ARs, but generally more abundant and diverse at natural reference patches. Taken together, all studied ecological parameters progressed towards reef ecosystem recovery, with varying influences of AR design and material. We recommend a combination of metal cages and layered concrete ARs to promote high fragment survival as well as natural coral recruitment. Ultimately, a longer period of monitoring is needed to fully determine the effectiveness reef restoration as conservation tool to support coral reef ecosystem recovery.

In Palawan, Philippines, Honda Bay is fast becoming a target recreational site for curious domestic and foreign visitors. The general objectives of this resource assessment are to gather information regarding status of the marine resources in Pandan Island, and to provide recommendations for their sustainable use. Assessment was done using line intercept transect (LIT), fish visual census (FVC) and an imaginary transect belt for coral cover, fish, and macro-invertebrates, respectively. Average live coral cover around Pandan Island can be categorized as good (57%), with stations 7 and 1 and 2 categorized as excellent (76-100%) and fair (26-50%) conditions, respectively. Some 178 fish species were recorded in Pandan Island waters of which seven (7) highly target and 29 common commercial fish species were found. The estimated total reef fish biomass around Pandan Island is 588 mt/ km2. A total of eight macro invertebrate (shells, etc.) species belonging to five families was found around Pandan Island. The study concluded that of these eight species, six are commercially important,Tridacnacro cea(taklobo), Tridacnasquamosa (taklobo), Hippopusporcellanus(taklobo), Trochusniloticus(topshell), Pinna nobilis (tarab), and Bohadschiamarmota (sea cucumber). Five of these species the T. crocea, T. squamosa, H. porcellanus, P. nobilis, and T. niloticus are listed as endangered species by International Union for Conservation of Nature. Keywords - target species, macro-invertebrates, coral cover, coral reefs, reef fish, conservation

Sea cucumbers (Echinodermata: Holothuroidea) are large and abundant members of marine benthic communities. Overexploitation worldwide has raised concern because they have important functions within ecosystems. The ecological roles of commercially exploited sea cucumbers (Aspidochirotida and Dendrochirotida) are reviewed here, focusing on recent literature. Of the more than 70 species commercially exploited, at least 12 regularly bury into sand and mud, playing major roles in bioturbation. Most aspidochirotids are deposit-feeders, reducing the organic load and redistributing surface sediments, making them bioremediators for coastal mariculture. Sea cucumbers excrete inorganic nitrogen and phosphorus, enhancing the productivity of benthic biota. This form of nutrient recycling is crucial in ecosystems in oligotrophic waters such as coral reefs. Feeding and excretion by sea cucumbers also act to increase seawater alkalinity which contributes to local buffering of ocean acidification. Sea cucumbers host more than 200 species of parasitic and commensal symbionts from seven phyla, thereby enhancing ecosystem biodiversity. They are preyed on by many taxa, thereby transferring animal tissue and nutrients (derived from detritus and microalgae) to higher trophic levels. Overexploitation of sea cucumbers is likely to decrease sediment health, reduce nutrient recycling and potential benefits of deposit-feeding to seawater chemistry, diminish biodiversity of associated symbionts, and reduce the transfer of organic matter from detritus to higher trophic levels. Ecosystem-based fisheries management needs to consider the importance of sea cucumbers in marine ecosystems and implement regulatory measures to safeguard their ecological roles.

Abstract. The Primeiras and Segundas Archipelago Reserve is a recently established marine protected area, the largest in Africa, located in the waters of Northern Mozambique. This protected area is of significant local economic importance and global ecological relevance, containing the southernmost coral reefs in Eastern Africa. However, information related to the marine ecosystem, notably benthic habitat is very scarce. Twelve atolls were mapped in the region using object-based image classification of very-high resolution satellite imagery (IKONOS, Quickbird, and WorldView-2). Geographically referenced data on benthic cover and depth were gathered in the course of three fieldwork expeditions covering a total of four atolls and two shallow reef structures in the Segundas Archipelago. The resulting map allows the estimation of three distinct types of coral cover (field, patches, spurs and grooves); the differentiation of sand, rubble and rock substrate; and the detection of seagrass and brown macroalgae, identifying up to 24 benthic habitats. Average overall accuracy was above 50%. The high variability of the optical properties on the reef systems, in large due to the connectivity with the mainland via plumes, while interesting from an ecological perspective increases the challenges for remote sensing of bottom cover. New information indicates the presence of deep benthic cover extending from the atolls, suggesting the need for further research on Coastal Eastern African corals, namely on their resilience and connectivity, and supporting current knowledge of the existence of an almost continuous coral reef from Kenya to Mozambique. Coral and fish biodiversity data have been analysed together with the satellite-derived maps. Results support the local perception that ecosystems are in decline and uncover new information about biodiversity’s spatial patterns. Our work provides a detailed depiction of marine habitats that may aid the management of the protected area, namely in the definition of fishing zones and coral cover monitoring.

Declining water quality is one of the main reasons of coral reef degradation in the Thousand Islands off the megacity Jakarta, Indonesia. Shifts in benthic community composition to higher soft coral abundances have been reported for many degraded reefs throughout the Indo-Pacific. However, it is not clear to what extent soft coral abundance and physiology are influenced by water quality. In this study, live benthic cover and water quality (i.e. dissolved inorganic nutrients (DIN), turbidity (NTU), and sedimentation) were assessed at three sites (< 20 km north of Jakarta) in Jakarta Bay (JB) and five sites along the outer Thousand Islands (20–60 km north of Jakarta). This was supplemented by measurements of photosynthetic yield and, for the first time, respiratory electron transport system (ETS) activity of two dominant soft coral genera, Sarcophyton spp. and Nephthea spp. Findings revealed highly eutrophic water conditions in JB compared to the outer Thousand Islands, with 44% higher DIN load (7.65 μM/L), 67% higher NTU (1.49 NTU) and 47% higher sedimentation rate (30.4 g m−2 d−1). Soft corals were the dominant type of coral cover within the bay (2.4% hard and 12.8% soft coral cover) compared to the outer Thousand Islands (28.3% hard and 6.9% soft coral cover). Soft coral abundances, photosynthetic yield, and ETS activity were highly correlated with key water quality parameters, particularly DIN and sedimentation rates. The findings suggest water quality controls the relative abundance and physiology of dominant soft corals in JB and may thus contribute to phase shifts from hard to soft coral dominance, highlighting the need to better manage water quality in order to prevent or reverse phase shifts.