Growth Dynamics of Zostera marina Transplants in the Nakdong Estuary Related to Environmental Changes

Abstract

Numerous seagrass habitat restoration projects have been attempted recently due to the remarkable decline in seagrass coverage. Seagrass transplants tend to adapt to a new environment after experiencing transplanting stress during the early stages of transplantation. Once acclimated, the transplants grow into healthy seagrass beds via vegetative propagation. The establishment and growth dynamics of transplanted seagrasses in bays and coasts are widely reported, but few studies have been conducted on estuaries in Korea. We transplanted Zostera marina in November 2007 and November 2008 in the Nakdong estuary using the staple method, and monitored the survival, adaptation, and growth dynamics of the transplants as well as environmental factors every month for 1 year. Both transplants adapted well to the new environment without initial losses and showed rapid productivity during early summer. However, density of transplants increased 320% in 1 year from the previous year s transplants but that decreased to 59% during the following year. This significant reduction in density in the second year may have been caused by exposure to low salinity (10 psu) for 3 weeks during the unusually long monsoon season. While the survival and growth dynamics of seagrass transplants planted in bays and coasts are mainly controlled by underwater photon flux density and water temperature, salinity was the critical factor for those planted in Nakdong estuary.

Growth and Population Dynamics of Zostera marina Due to Changes in Sediment Composition in the Seomjin Estuary, Korea

“…따라서 영양염 농도는 잘 피의 생장을 조절하는 요인이 될 수 있다. 거머리말의 생태에 관 한 연구는 주로 연안에서 이루어졌고, 하구에 나타나는 거머리말에 대한 자료는 매우 빈약한 실정이다 (Park et al, 2011).…”

“…하구는 지속적으로 담수가 유입되어 그 유입량에 따라 수 중광량, 염분, 수온과 영양염의 농도가 연안에 비해 역동적으로 나 타난다 (Day et al, 1989). 강으로부터 유입되는 담수, 영양염과 실 트질 부유물은 수중광량을 감소시키고 플랑크톤의 증식과 잘피 잎 의 부착 생물량을 증가시켜 잘피 군락에 피해를 입힌다 (Day et al, 1989;Koch, 2001;Park et al, 2011). 특히, 섬진강 하구는 우수 기나 댐 방류와 같은 대규모 담수의 유입으로 물의 흐름이 빨라져 퇴 적물의 이동이나 흐름이 빨라지게 되어 퇴적물 성상의 변동이 일 어나며, 이곳에 서식하는 거머리말 군락지에 치명적인 영향을 미 칠 수 있다.…”