Recent Trends of &amp;lt;i&amp;gt;Zostera marina&amp;lt;/i&amp;gt; (Eelgrass) in a Highly Eutrophic Coastal Lagoon in the Mid-Atlantic Region (USA)

Michael J Kennish,Gregg P Sakowicz,Benjamin Fertig

doi:10.4236/oje.2016.65025

Recent Trends of &lt;i&gt;Zostera marina&lt;/i&gt; (Eelgrass) in a Highly Eutrophic Coastal Lagoon in the Mid-Atlantic Region (USA)

Michael J Kennish, Gregg P Sakowicz + Show 1 more

Open Access

https://doi.org/10.4236/oje.2016.65025

Copy DOI

Abstract

Spatial and temporal characteristics of Zostera marina (eelgrass) in the Barnegat Bay-Little Egg Harbor Estuary are compared before (2004-2011) and after (2012-2013) major fertilizer legislation (Fertilizer Law A2290) was enacted in New Jersey (USA) to reduce nutrient inputs from fertilizers to water bodies in the state. A significant decrease of Z. marina biomass and areal cover occurred in this eutrophic estuary between 2004 and 2011 concomitantly with increasing nitrogen and phosphorus loading from the watershed. The rate of decline in aboveground and belowground biomass was significantly sharper during 2004-2006 than during 2008-2010. In 2010, Z. marina biomass dropped to a very low level (mean aboveground biomass = 7.7 g dry wt mǄ mean belowground biomass = 27.0 g dry wt m&#452), persisting through the last sampling period (October-November) in 2013. Biomass and areal cover of Z. marina decreased even further after Fertilizer Law A2290 was enacted in January 2012, with the lowest values recorded from August to November each year. These low values are the result of ongoing eutrophication of the system. More seagrass monitoring and research are necessary in future years to determine if the fertilizer law will have a positive effect on Z. marina condition in the estuary over the long term.

Highlights

Barnegat Bay-Little Egg Harbor (BB-LEH) Estuary, New Jersey (Figure 1), is a eutrophic coastal lagoon [1]-[9]
Plant characteristics of Z. marina measured in 2004-2011 (Table 2) serve as a baseline for more recent changes of eelgrass characteristics in the estuary associated with ongoing eutrophication and potentially associated to some extent with nutrient loading regulations that recently came into effect
Lathrop et al [20], conducting remotely-sensed surveys, clearly showed that eelgrass percent cover decreased in the BB-LEH system during the first decade of the 2000s. These findings indicate important decreases in Z. marina biomass and areal cover values between 2004 and 2013

Summary

Introduction

Barnegat Bay-Little Egg Harbor (BB-LEH) Estuary, New Jersey (Figure 1), is a eutrophic coastal lagoon [1]-[9]. Over the past two decades, the eutrophic condition of the estuary has increased, and it is classified as a highly eutrophic system [4]-[6] [9] [10]. This 280 km estuarine water body is susceptible to nutrient loading because it is shallow, poorly flushed, and bordered by a highly developed and altered watershed (1730 km area) that acts as a conduit for nutrient transport to the estuary.

Methods

Results

Discussion

Conclusion