Life Stage, Gender and Movement of Blue Crabs (Callinectes sapidus) in Lake Mattamuskeet and Connecting Canals

In their ranges on east and south coasts of the Americas as well as their established invasions in the Adriatic and Baltic,blue crabs,Callinectes sapidus,inhabit estuaries,sounds and coastal oceans and are commercially and ecologically important.How crabs move in response to physical variables is important to management.We monitored life stages at canal control structures,assessed gender ratios with recreational crabbing,learned from crabbers,and studied movements of tagged crabs in a canal connecting Lake Mattamuskeet to the Pamlico sound.Juveniles enter the lake through two of 4 canals connecting to the sounds.Females migrate out through one canal.The lake standing population is about 70% male.Movements of 240 crabs in August 2012 and 102 crabs in October 2014 were quantified using RFID tags with co-located meteorological and oceanographic devices.Non-spawning females and males are nomadic.Crabs released in the canal move in response to changes in water depth and go with the flow,toward the Pamlico Sound(summer 76% and fall 78%).What crabbers describe as a fall migration appears to be concentration of crabs in warmer deeper canals and then southern movement with flow generated by strong north winds.To be effective,management strategies like migratory corridors require understanding of crab movements.

Mitochondrial Haplotypes suggest Genetic Component for Habitat Preference in Blue Crabs

Atlantic blue crabs(Callinectes sapidus)are ecologically and commercially fundamental.Life stages are punctuated with migration.Adults and juveniles live in estuaries and sounds.Larval stages develop in the coastal ocean.Juvenile and adult crabs occupy habitats from high salinities to fresh water.We determined whether maturing juvenile and adult blue crab habitat use is reflected in mitochondrial cytochrome oxidase 1 haplotypes.High salinity crabs had lower haplotype diversity(0.7260±.03900)compared to spawning crabs(0.9841±.00021)and low salinity crabs(0.94154±.00118).Significant pairwise differences in haplotypes were found between high salinity and spawning crabs(Nm=0.26018,p<0.001),and between high salinity and low salinity crabs(Nm=0.19482,p<0.001)indicating a lack of gene flow.Crabs from high salinity had highly significant genetic differentiation compared to spawning crabs(Fst=0.11830,p<0.001)and low salinity crabs(Fst=0.09689,p<0.001).Results support the hypothesis that genetics influence habitat selection.Crab larvae mix in the coastal ocean but occupy specific habitats upon return to sounds and estuaries.These findings have implications for the management of fisheries.

Ecosystem Restoration:Enhancing Ecosystem Services with Floating Aquaculture

Restoration ecologists recognize the need for restoring ecosystem services in sustainable ways that meet societal needs.In the UK,Ireland,Australia,and some US states the goal is restoring native oyster reefs.In other states,failures at restoration due to poor water quality and predation have focused restoration activities on techniques that work,restoring intertidal reefs and generating living shorelines that reduce or reverse erosion.In the United States,restoring water quality and reducing or reversing erosion are societally accepted entry points for repairing estuarine ecosystems.This study is an overview of the current status of oyster reef restoration and provide a novel approach called“oyster reef in a bag”.Combining oyster reef restoration efforts with existing floating oyster aquaculture technology generates novel ecosystems that are a combination of biofouling and oyster reef communities.These novel ecosystems could be a practical beginning to improve water quality,mitigate erosion and restore higher trophic level ecosystem services.