Mangrove in marine ecosystem have function to help continuing food chain directly, provide food for benthics organism, include macrozoo and microzoo, and ephiphyte  and indirectly as habitat, nursery ground and spawning ground (Nontji (1993), Valiela et al, (2001).  This research analyzed macrozoobenthics community in mangrove forest, Penyu Island, Tanjung Benoa, and counting correlation between mangrove density and macrozoobenthics abundance. 4 mangroves species (Bruguiera gymnorrhiza, Rhizopora mucronata, Rhizopora stylosa dan Sonneratia alba) and 22 macrozoobenthics genus (Cvpraeidae, Naticidae, Cerithiidae, Mathildidae, Mitridae, Columbellidae, Buccinidae, Neritidae, Fasciolariidae, Smaragdinellidae, Littorinidae, Trochidae, Costellariidae, Terebridae, Opisthobranchia, Pyramidellomorpha, Littorinidae, Conidae, Thaididae, Potamididae, Turritellidae, Nassariidae) were identified from 3 stasions over the Island. Rhizopora stylosa have the highest importance index in Penyu Island mangroves community and than Bruguiera gymnorrhiza. The highest abundance documented in station 1 for 385.2 ind/m2 and then station 2 for 271.58 ind/m2 and the lowest is station 3 247.71 ind/m2. Cerithium sp recorded as dominant species and Turritella cochlea and Cyprae kieneri as inferior species. Macrozoobenthos community in Penyu Island is being stable base d on high diversity index, moderate eveness index and low dominance index. The regression equation acquired Y = -60.524X + 119.94 and revealed correlation 40.05% and explain 16.04% macrozoobenthics varians. From the study inconclusive there are no correlation between mangroves density and macrozoobenthics abundance.

Gracilaria sp is red alga which belong to class rhodophyceae. It can grow in shallow salt water with a general characteristic is having a cylindrical and branched thallus form. Seaweed cultivation can be performed through IMTA (Integrated Multi Trophic Aquaculture) method. The basic principle of cultivation through the IMTA method is utilizing service of the low thropic level species in marine ecosystems, such as shells and seaweed.  This method is believed to be able to overcome the environmental problems caused by cultivation activities, such as feces and uneaten feed. This research was perfomed 45 days, from February 25 to April 11, 2017. It was held at Geger Beach, Nusa Dua, Badung Regency, Bali, using a complete randomized design method that consist of three treatments and three repetition for each treatment. Treatment control (T1) consisted of 10 bunches of seaweed 100 grams without the abalone, treatement 2 (T2) consisted of 10 bunches of seaweed 100 grams and 20 abalones and treatement 3 (T3) consisted of 10 bunches of seaweed 100 grams and 40 abalones. The result showed that specific growth rate in Gracilaria sp.  was highest in treatment T1, compared to treatment T2 and T3. This was caused by the cage construction of abalone amd the present of small mesh size net to cover the seaweed  planting, which made the growth was not optimal.  However, the use of a nets system in seaweed cultivation could minimize the loss of thallus. It was proved by the survival rate of seaweed in first, second and third, that is averagely high, ranging from 90% to 100%. Physical and chemical water quality parameters are also measured, and It showed that the water quality was suitable for the cultivation of both, seaweed and abalone.