Exploring environmental condition of silvofishery pond to support the sustainability of mangrove management in Berau Regency, Indonesia

Background

On the islands of Kalimantan and Sulawesi, Indonesia, mangroves are threatened by conversion into brackish water aquaculture ponds. To combat mangrove deforestation, government ministries and academia have promoted silvofishery ponds as a method of sustainably combining fish or shrimp aquaculture with mangrove restoration and protection. Understanding the biotic and abiotic factors impacting silvofishery ponds is important to inform management decisions and increase support for silvofishery ponds.

Goals and Methods

This study aims to assess and identify the conditions and limiting factors of silvofishery ponds in Berau Regency, East Kalimantan Province, Indonesia. Soil and water quality samples were collected at nine 10 by 10 meter observation plots and 13 sampling points in and around silvofishery ponds. The authors also collected data on mangrove species, mangrove measurements, mangrove cover, mangrove to pond ratio, and local climate. The authors used descriptive statistics to analyze the data and compare the data to acceptable water quality standards. They compared topography, tidal, water quality, soil quality, and climate data with land suitability criteria from the literature review to determine limiting factors for land suitability for silvofishery ponds.

Conclusions and Takeaways

Soil quality is a key limiting factor for silvofishery ponds due to pond sediment having low pH and low nitrogen availability. Soil remediation methods, including drying, submerging, flushing or liming for pH, and fertilizer addition for nitrogen, are recommended to decrease the solubility of various toxic compounds and increase nutrient availability. Increasing mangrove density and the proportion of mangroves to pond area in silvofishery systems are also important areas of improvement for mangrove ecosystem health and services. Regarding pond structure, the authors recommend the komplangan pond model, with the mangrove area separated from the aquaculture pond, over the empang parit model, where aquaculture areas border a central patch of mangroves. The empang parit model typically has worse water quality throughout the pond. The authors also provide acceptable ranges for many other water and soil quality indicators that could be useful for practitioners interested in silvofishery systems.