Estuaries are coastal areas that have a fairly high fertility rate. This region can be said to be fertile because it is influenced by such physical factors as temperature, turbidity, light, and current as well as such chemical factors as salinity, dissolved oxygen, pH, and nutrient content. The estuary of the Banjar Kemuning River is a coastal area with a lot of human activities, and it is close to the mainland, causing the change in the nutrient content in the waters. The nutrient content in the waters is closely related to the phytoplankton abundance, as the higher the nutrient content in the waters, the greater the phytoplankton abundance and the chlorophyll-a content. The level of chlorophyll-a content in the waters can indirectly be used as an indicator of the phytoplankton abundance, which can determine the level of fertility of these waters. The purpose of this study was to determine the relationship between the phytoplankton abundance and the chlorophyll-a content in the estuary of the Banjar Kemuning River. This study is observational research with data analysis using linear regression, simple correlation (Pearson), and ANOVA. In addition, the data collection was carried out by purposive random sampling at predetermined points of stations. The results of this study indicated that the phytoplankton abundance and the chlorophyll-a content at the estuary of Banjar Kemuning River during different months were significantly different (P<0.05). The averaverage chlorophyll-a content during the study was 0.958 µg/L, 0.998 µg/L, and 1.167 µg/L. The conclusion was drawn that there is a difference between the phytoplankton abundance and the chlorophyll-a content each month and classified into high correlation.

Sedati is one of the Sidoarjo Regency's Coastal Areas, which has potential resources in capture fisheries. Many industries in Sedati have caused a decrease in the aquatic productivity and aquatic organism conditions, including gastropods. Gastropods are easy to find in various habitats, but their distribution is highly dependent on the habitat conditions such as physical, chemical and biological factors. Gastropods are sensitive to environmental changes and can withstand the environmental changes that are not too wide to be used as indicators of environmental pollution. This study aims to determine the structure of the gastropod community in the Sedati Waters. The research was performed using an observation method. The gastropod samples were taken using a dredge net, while the substrate samples were collected using Ekman grab. The gastropods found in Sedati Waters from October to December are nine species from 2 orders and six families. The species most commonly found in R. venosa, while the least is C. ventricosa. The abundance index of gastropods every month shows a marked difference between stations but not the other main parameters. The diversity index value was between 1.4846-2.0897. The evenness index value reached between 0.8284 and 0.9548. The dominance index ranged from 0.16 to 0.2299. The community structure of gastropods in the Sedati Waters, Sidoarjo, East Java shows a significant difference (p<0.05) between stations and belongs to the medium category.

Sidoarjo waters is a buffer zone of Surabaya City. Sidoarjo has many industries such as the metal, textile and waste treatment industries. Many industrial wastes are discharged into Sidoarjo waters, especially Sedati. Waste entering the waters can affect water quality, which influences the living things. One of them is echinoderms. This research purpose to find out the differences of echinoderms in Sedati waters. The research was done from October to December 2019. The data obtained were analyzed descriptively quantitatively using the diversity index Shanon Winner and ANOVA. The results showed that the diversity of echinoderms species found has significant differences. Species were found like Archaster typicus, Echinothrix calamaris, and Ophiothrix sp. The average diversity of echinoderms was 0.4119 + 0.1479 (H < 1) so it was classified as low criteria with polluted water quality. The low variation of echinoderms can be caused by several factors such as location, season, physical quality, chemical quality, biotic factors and the fishing gear used. One of the efforts reduces the impact of pollution is to treat waste before it transferred to the release and move the fishing gear used to be more environmentally friendly.

Indonesia has a lot of mollusks wealth, one of which is gastropods. Sedati waters are one of the coastal areas of Sidoarjo Regency which has the potential of for mollusk resources in the form of sea snails. Catching mollusks continuously can cause the threat of decreasing the population of mollusks in the waters. This study aims to determine the variability of the gastropods population structure in Sedati waters, Sidoarjo Regency, East Java. This study uses an observation method with analysis statistic of variance. Gastropods identification was done by measuring length and weight, and looking at morphological characteristics. The result are gastropods found and dominant in Sedati waters in October to December are Natica vitellus, Notocochlis tigrina, Babylonia spirata, Turricula javana, Cryptospira ventricosa, Murex trapa, Rapana venosa, Nassarius olivaceus and Nassarius stolatus. Gastropod density and biomass values at station C is were greater than station A and B, with the highest values in December. The highest average value of gastropods biomass was 0.78 ton/km2 and the highest average gastropods density was 5 ind/10m2, namely in December at station C. The distribution of gastropods in Sedati waters was influenced by environmental such as substrate conditions, water quality and oceanographic, as well as fishing activities by fishermen.

This study used a combination of chicken manure and chicken broth which was fermented first with the aim to knowing the effect and the best dose of the combination of chicken manure and broth so as to increase the amount of Daphnia magna production optimally. This research is experimental using Completely Randomized Design method which consists of 4 treatments with 5 replications. Data analysis was processed using ANOVA and Duncan. The results showed that the fermentation of manure and chicken broth with a dose of P3 (7.5 mL/L) on day 8 gave the highest yield (41950 ind/L) compared to other treatments. Based on ANOVA analysis, it was shown that the combination treatment of chicken manure and broth compared with no combination on the count of Daphnia magna production had a significant effect (P<0.05). Duncan's test results showed that P3 treatment was significantly different from P0 and P1 but not significantly different from P2 treatment, with an average difference of P2 (5mL/L) 7419 ind/L and P3 (7.5mL/L) 8328 ind/L for 14 days growth.

Live feed is one of the most important factors of the success of fish farming, especially in fish hatchery activities. Live feed that has the potential to support cultivation activities is Daphnia magna. One of the problems on Daphnia magna culture is feed availability that can meet the nutrients in Daphnia magna. The aim of this research was to study the effect of providing feed from combination of chicken broth and chicken manure on the nutritional value of Daphnia magna. This study was experimental using the RAL method consisting of 4 treatments with 5 replications, namely control treatment (P0) 7.5 mL/L dose of feed, (P1) 2.5 mL/L dose of fermented feed, (P2) 5 mL/L dose of fermented feed and (P3) 7.5 mL/L dose of fermented feed. Data analysis was processed using ANOVA and Duncan. The result of this study has a significant effect (P<0.05) on nutritional content of Daphnia magna with the best dose in P3 which can affect the highest protein (51,98%) and highest fat (12,17%) of Daphnia magna. The highest fiber (13,32%) of Daphnia magna was found in the P1 treatment and the highest carbohydrates (37,51%) of Daphnia magna was found in the P0 treatment.