Estimating Connectivity of Hard Clam (Mercenaria mercenaria) and Eastern Oyster (Crassostrea virginica) Larvae in Barnegat Bay

Jacob D Goodwin,Daphne M Munroe,Neil K Ganju,James Vasslides,Zafer Defne

doi:10.3390/jmse7060167

Abstract

Many marine organisms have a well-known adult sessile stage. Unfortunately, our lack of knowledge regarding their larval transient stage hinders our understanding of their basic ecology and connectivity. Larvae can have swimming behavior that influences their transport within the marine environment. Understanding the larval stage provides insight into population connectivity that can help strategically identify areas for restoration. Current techniques for understanding the larval stage include modeling that combines particle attributes (e.g., larval behavior) with physical processes of water movement to contribute to our understanding of connectivity trends. This study builds on those methods by using a previously developed retention clock matrix (RCM) to illustrate time dependent connectivity of two species of shellfish between areas and over a range of larval durations. The RCM was previously used on physical parameters but we expand the concept by applying it to biology. A new metric, difference RCM (DRCM), is introduced to quantify changes in connectivity under different scenarios. Broad spatial trends were similar for all behavior types with a general south to north progression of particles. The DRCMs illustrate differences between neutral particles and those with behavior in northern regions where stratification was higher, indicating that larval behavior influenced transport. Based on these findings, particle behavior led to small differences (north to south movement) in transport patterns in areas with higher salinity gradients (the northern part of the system) compared to neutral particles. Overall, the dominant direction for particle movement was from south to north, which at times was enhanced by winds from the south. Clam and oyster restoration in the southern portion of Barnegat Bay could serve as a larval supply for populations in the north. These model results show that coupled hydrodynamic and particle tracking models have implications for fisheries management and restoration activities.

Highlights

IntroductionCultural, and ecological value by supporting local fisheries [1], creating habitat [2], and providing ecosystem services (e.g., water filtration [3])
Shellfish provide economic, cultural, and ecological value by supporting local fisheries [1], creating habitat [2], and providing ecosystem services
This work shows that physical parameters influenced by climate patterns can have a large impact on larval connectivity Understanding the larval stage provides insight into shellfish population connectivity that can help strategically identify areas for restoration

Summary

Introduction

Cultural, and ecological value by supporting local fisheries [1], creating habitat [2], and providing ecosystem services (e.g., water filtration [3]). As much as we are commonly interested in the adult shellfish stages, it is the dispersive planktonic larval stage that influences population distributions because the juvenile and adult stages are sessile [2,6]. Some research has been conducted on the crucial planktonic stage that governs the recruitment patterns in a shellfish population [7,8]. Understanding the abundance and distribution patterns of shellfish larvae requires a large number of samples over time and space [9,10,11], but advances in larval transport modeling can provide insight into the transient life stage of these ecologically and economically important shellfish [8,12,13,14]

Methods

Results

Conclusion