The individual behavior of orangutan (Pongoabeli) before reintroduction to the wild was studied from March to June 2012 in orangutan quarantine station Batumbelin Sibolangit, Deli Serdang. The research used focal animal sampling method, at the same time the data recording was taken using instantenous method. The result showed that solitary behavior (39.34%) which was dominated by feeding (20.60%). The second highest (35.31%) was resting which was dominating by sitting (16.87%) followed by moving behavior (13.58%) which mostly was branching (7.54%). The least activity was competitive behavior (1.88%) which was dominated by streaking down each other (0.82%). The result also indicated an abnormal behavior among 3 orangutans observed such as eating their own feces.

The study of the growth rate of Branchionus plicatilis O.F. Muller population with the addition of a mixture of yeast, chicken manure fertilizer, urea, and triple super phosphate (CAKAP) was conducted in June 2012. Four treatments namely MK, MP1, Mp2, and MP3 were used in this experiment. MP1 consisted of CAKAP medium, 0.3 g/2L of yeast; MP1 consisted of CAKAP medium, 0.3 g/2L of yeast, and 0.1 ml/2L of fish oil. MP2 and MP3 have the composition as MP1 but show different concentrations of fish oil which were 0.2 and 0.3 ml/2L each. Every treatment had six replicates. The result showed that the highest growth rate of Branchionusplicatilis O F Muller was obtained from the first observation (day 2) of MP2 medium with the rate 2.605 individual x 2 x 10-3 per day while the lowest one was shown by MP3 medium which was 2.282 individual x 2 x 10-3 per day.

Research on Soil Macrofauna as Bioindicator in Plantation Areas Given Palm Oil Mill Liquid Waste as Fertilizer was conducted in 2021. Samples were taken in Long Bed, Flat Bed, and Control areas using Purposive Sampling and Squares and Hand Sorting methods. Each location is determined by 9 sampling points. Soil macrofauna samples were identified in the USU FMIPA Ecology laboratory. From the results of the study, there were 3 soil macrofauna phyla, namely the Annelida phylum, which consisted of 1 class, 1 order, 2 families, and 2 species. Phylum Arthropoda consists of 5 classes, 10 orders, 16 families, and 27 species. Phylum Mollusca consists of 1 class, 1 order, 1 family, and 1 species. The highest population density (K) was obtained from the species Macrotermes gilvus, which was 81.10 individuals/m2 in the Control area, followed by Ponthoscolex corethrurus at 78.81 individuals/m2 in the Flat Bed area. The highest relative density (KR) was found in the species Macrotermes gilvus, which was 49.1% in the control area, followed by Ponthoscolex corethrurus at 46.84% in the Long Bed area. The highest frequency of presence (FK) was found in the Ponthoscolex corethrurus species, which was 100% in the Control and Flat Bed areas, and 88.88% in the Long Bed areas. Species that can live and reproduce well as bioindicators are Ponthoscolex corethrurus in the Long Bed area, followed by the Flat Bed and Control areas. The highest diversity index value was found in the Flat Bed area, which was 3,831 with the criteria for diversity being high, the distribution of the number of individuals for each species was high, the community stability was good and the soil community had not been polluted, while the Equitabilitas value was 1,258 with the criteria for high uniformity, stable community. The application of palm oil mill effluent as fertilizer to the plantation area can increase the life of the soil macrofauna, and the physical-chemical properties of the soil.

Oil palm plantations of PT. Supra Matra Abadi has used palm oil mill effluent to the plantation area as fertilizer (Land Application) to part of its plantation area. The difference in land use and management in the plantation area also determines the presence, both species, density, diversity index value, and soil macrofauna uniformity index. Soil macrofauna plays a role in maintaining the balance of the soil ecosystem. This research has been conducted at PT. Supra Matra Abadi, located in Kebun Panji Bay, Kampung Rakyat District, Labuhanbatu Selatan Regency, North Sumatra Province in May-July 2018. This research was conducted to determine the presence of species, population density, diversity index values, and uniformity of soil macrofauna on oil palm plantations. Determination of the sampling point is done by the Purposive Random Sampling method, soil macrofauna sampling using the Quadratic and Hand Sorting methods. There are 15 species of soil macrofauna which are grouped into 2 phyla, 5 classes, 9 orders, 12 families, and 15 genera. The highest density value was found in the area of plantations that were not given liquid palm oil mill effluent as fertilizer (Non Land Application) of 282.15 ind / m2 and the highest diversity index value was found in the area of oil palm plantations which were fertilized with palm oil mill liquid waste to land area (Land Application) which shows that the condition of the oil palm plantation ecosystem which is fertilized with palm oil mill effluent (Land Application) can support the life, diversity, and uniformity of soil macrofauna.

Coral reefs are vulnerable ecosystems that can change over time due to natural factors. Bleaching is one of the natural phenomena that has an impact on coral ecosystems in Jaboi area of Weh Island, Sabang City, Indonesia. Therefore, the aim of the study is to measure the coral ecological conditions and recovery which includes coral cover, coral diversity, and recruitment in the waters of Jaboi, Weh Island. Benthic data collection used the Point Intercept Transect method, while coral recruitment data collection used the Belt Transect method. The level of diversity was measured based on an index from Shannon Wiener, then the coral recovery was calculated based on the percentage of coral cover and the number of juvenile corals. The result showed that the coral cover and diversity in Jaboi waters were in a moderate condition, with a cover score of 40% and the diversity of H = 1.4294. The coral recovery in Jaboi waters for the last nine years has decreased, so the potential to restore natural ecosystems is very low. This also showed by the juvenile corals which have a very low density (0.04 colonies/m2).