Abstract. Ambo-Rappe R, La Nafie YA, Syafiuddin, Limbong SR, Asriani N, Handayani NT, Lisdayanti E. 2019. Short Communication: Restoration of seagrass Enhalus acoroides using a combination of generative and vegetative techniques. Biodiversitas 20: 3358-3363. Seagrass areas have been declining in extent worldwide, with associated loss in seagrass ecosystem functions and services. Seagrass restoration is important to mitigate, halt and reverse such declines and their consequences. Generative propagation has benefits in terms of genetic biodiversity, however, survival of seagrass seedlings has often been poor especially in high energy environments. Terrestrial restoration often uses shade trees to protect vulnerable seedlings. This study aimed to evaluate the feasibility of a similar approach in the marine environment, using adult plants to protect seedlings of the tropical seagrass Enhalus acoroides (L.f.) Royle. Enhalus seeds taken from a donor bed were germinated and grown into seedlings, then planted in a location with high hydrodynamic exposure at three different densities (high, medium, and low). Adult Enhalus transplants were co-planted to provide three levels of protection: fifty (high), ten (medium), and none (no protection). Results showed that high-density seedling co-planting with high protection from adult transplants had significantly (p< 0.05) higher six-month survival rate compared to the other treatments. Our results indicate that, even in high energy environments, co-planting seedlings with adult transplants may combine the advantages of generative and vegetative propagation methods, promoting greater short-term effectiveness in terms of seedlings survival and growth in the restored seagrass meadows.

As the largest trepang producer in the world, Indonesian trepang product still depends on wild catches. This wild catch could cause overfishing. In many fishing areas, sea cucumber populations have decreased to the point where they can be considered as a rare species. The wild catch could lead to a negative impact on size at maturity. Biologically, there are two types of reproductive strategies at marine organisms, i.e. ‘r-selection’ and ‘K-selection’. The ‘r-selection’ type was found in organisms that are dominantly controlled by their environmental factors and tend to reach physical maturation faster, while the ‘K-selection’ type was controlled more by biological factors, such as the presence of competitors. This study aims to analyze the size at the maturity of sea cucumber Holothuria scabra for different years to find out if the size at maturity can be used as a reference of the overfishing sign in the Wallacea region. The H. scabra or sandfishes were taken from the catches of fishermen at the Sub-district Liukang Tupabbiring Utara, Pangkep Regency, South Sulawesi, Indonesia. The Liukang Tupabbiring area is in the Spermonde Islands region, which is part of the Wallace line trajectory. Samplings were carried out for four years, from 2016 to 2019. The parameters measured were a total length (TL), total weight (TW), and gutted body weight (BW). The parameters observed were the color and stage of the gonad. The sizes at maturities were defined as the percentage of sexually mature, which were the sandfish with gonad stages of III, IV, and V. The study reveals that the size at maturity of sandfish was reached at a smaller size than previously reported. Biologically, smaller sizes at maturity could be a sign that sandfish has overfishing. As one organism whose biological organ structure was still primitive, Sea cucumber probably maintains the continuity of its generation by adapting reproductive strategy “r-selection type”.

Sandfish culture had been implemented for more than 20 years but has frequently failed to yield the expected results due to low survival rates. A decrease in salinity during the rainy season was suspected as a cause of sandfish mortality. This study aimed to assess the influence of salinity on sandfish survival rates. Treatments included sudden shock and gradual acclimation trial methods. Even though the results of this study indicate a mean survival rate of 50% at 14.6 ppt, the survival rate fell drastically as water salinity was reduced below the salinity of saltwater bony fish body fluids (around 18 ppt). Sandfish cannot live in water with salinity lower than the osmotic body fluid of freshwater bony fish (around 14 ppt). Therefore, for the cultivation of sandfish in coastal ponds, salinity should not be allowed to fall below a minimum of 18 ppt.

The sandfish Holothuria scabra is a benthic animal of high ecological and economic value. The high economic value of sandfish has led to declining populations due to overfishing. Initiatives to improve sandfish production have included restocking, sea-ranching and aquaculture (captive breeding and grow-out). These initiatives require a supply of animals (seed and/or broodstock) that often originate far from the location where they are needed. This calls for a good transportation system so that the sandfish arrive in good condition. This study aimed to assess the evisceration rate of sandfish transported using open and closed transportation modes. During the study, different modes of packing, density, transportation time, and holding time were evaluated. This study indicated that delivery using open systems gave poor results; besides being less practical, post-transport evisceration was very high. The ratio of oxygen and water and the packing density did not appear to affect the sandfish evisceration rate. Evisceration seemed to be triggered by the presence of dead and decaying sandfish in the bag. Sandfish that survived transportation generally recovered swiftly after being placed in a pre-prepared holding tank. The transported sandfish were used for multitrophic aquaculture and the post-transport survival ratio was very high.

Biomarkers are considered as appropriate and sensitive tools to detect contaminants which effects are recorded on a sentinel organism. Research on simple biomarkers has been conducted in the laboratory to detect the toxicity of low concentrations of Arsenic by using green mussels, Perna Viridis, as sentinel organisms. The simple biomarkers used are biogenesis, Stress On Stress (SOS), and the condition index. Green mussels of 2.5-3.5 cm were exposed to concentrations of 0, 0.008, 0.038 and 0.19 mg/L of arsenic for 14 days. The results revealed that biogenesis was not sensitive to arsenic toxicity in green mussels. The air survival test or Stress on Stress was tested in terms of LT50 of Kaplan-Meier test. The results showed that LT50 for treatments of 0, 0.008, 0.038 and 0.19 mg/L were 3.15, 2.76, 2,63 and 3.03 days respectively. It demonstrated that the air survival of mussels in control was longer than those were exposed to a series of arsenic concentrations descriptively, but statistically, they were not significantly different. However, the condition index of the green mussel revealed a significant difference statistically between control and 0.19 mg/L of Arsenic. This suggested that the condition index can detect the toxicity of Arsenic to the green mussel.