Life Stage, Gender and Movement of Blue Crabs (Callinectis 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, Callinectis 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.

Losing the Way

In this chapter, Huler loses his way from Lawson’s trek. Huler crosses the Neuse, a river going through the Piedmont, and passes the coastal plain into the Pamlico Sound. He compares Lawson’s writings to the modern environment in time, pointing out the size and current of the river. However, Huler mentions that the waterfall that Lawson found cannot be the Falls of the Neuse. After realizing that Lawson disappears past Hillsborough, Huler begins south of Raleigh where he passes many churches, religious buildings, and minority communities. Huler makes a couple of stops in Clayton to eat and rest before crossing the Neuse and coming across tobacco country.

Photon-Counting Lidar: An Adaptive Signal Detection Method for Different Land Cover Types in Coastal Areas

Airborne or space-borne photon-counting lidar can provide successive photon clouds of the Earth’s surface. The distribution and density of signal photons are very different because different land cover types have different surface profiles and reflectance, especially in coastal areas where the land cover types are various and complex. A new adaptive signal photon detection method is proposed to extract the signal photons for different land cover types from the raw photons captured by the MABEL (Multiple Altimeter Beam Experimental Lidar) photon-counting lidar in coastal areas. First, the surface types with 30 m resolution are obtained via matching the geographic coordinates of the MABEL trajectory with the NLCD (National Land Cover Database) datasets. Second, in each along-track segment with a specific land cover type, an improved DBSCAN (Density-Based Spatial Clustering of Applications with Noise) algorithm with adaptive thresholds and a JONSWAP (Joint North Sea Wave Project) wave algorithm is proposed and integrated to detect signal photons on different surface types. The result in Pamlico Sound indicates that this new method can effectively detect signal photons and successfully eliminate noise photons below the water level, whereas the MABEL result failed to extract the signal photons in vegetation segments and failed to discard the after-pulsing noise photons. In the Atlantic Ocean and Pamlico Sound, the errors of the RMS (Root Mean Square) wave height between our result and in-situ result are −0.06 m and 0.00 m, respectively. However, between the MABEL and in-situ result, the errors are −0.44 m and −0.37 m, respectively. The mean vegetation height between the East Lake and Pamlico Sound was also calculated as 15.17 m using the detecting signal photons from our method, which agrees well with the results (15.56 m) from the GFCH (Global Forest Canopy Height) dataset. Overall, for different land cover types in coastal areas, our study indicates that the proposed method can significantly improve the performance of the signal photon detection for photon-counting lidar data, and the detected signal photons can further obtain the water levels and vegetation heights. The proposed approach can also be extended for ICESat-2 (Ice, Cloud, and land Elevation Satellite-2) datasets in the future.

A spatial kernel density method to estimate the diet composition of fish

We present a novel spatially explicit kernel density approach to estimate the proportional contribution of a prey to a predator’s diet by mass. First, we compared the spatial estimator to a traditional cluster-based approach using a Monte Carlo simulation study. Next, we compared the diet composition of three predators from Pamlico Sound, North Carolina, to evaluate how ignoring spatial correlation affects diet estimates. The spatial estimator had lower mean squared error values compared with the traditional cluster-based estimator for all Monte Carlo simulations. Incorporating spatial correlation when estimating the predator’s diet resulted in a consistent increase in precision across multiple levels of spatial correlation. Bias was often similar between the two estimators; however, when it differed it mostly favored the spatial estimator. The two estimators produced different estimates of proportional contribution of prey to the diets of the three field-collected predator species, especially when spatial correlation was strong and prey were consumed in patchy areas. Our simulation and empirical data provide strong evidence that data on food habits should be modeled using spatial approaches and not treated as spatially independent.

RESPONSE OF OREGON INLET TO PEA ISLAND BREACHING

This study aims to assess the effects of a new inlet on the hydrodynamics of a semi-permanent tidal inlet and the back-barrier sound. Research on dual-inlet interactions is motivated by the increased vulnerability of barrier islands to breaching during hurricanes, phenomenon that can have important consequences on the hydrodynamics and morphology of a barrier island system with pre-existing inlets. This particular study takes place in the northern Outer Banks of North Carolina, where Oregon Inlet is the main inlet connecting the Atlantic Ocean with the Albemarle-Pamlico Sound. During Hurricane Irene in 2011, Pea Island – the island south of Oregon Inlet – was breached creating a new inlet that remained open until 2013. Dual-inlet interactions between Oregon Inlet and the new inlet in Pea Island are analyzed by means of numerical modeling experiments. Changes in flow velocities, water levels, and the tidal prism of Oregon Inlet due to the new inlet are computed for different wave and water level conditions. In addition to the actual inlet that opened in 2011, the effects of idealized inlets with different geometries and location are also included in this study. Results indicate that the original breach in Pea Island did not modify the dynamics of Oregon Inlet. Instead, its effects were restricted to a 5 km radius that extended mostly into the sound. The relative small size of the breach and its distance from Oregon Inlet are the two main factors that prevented dual-inlet interaction. Exploration of idealized breaching scenarios in Pea Island suggests that inlet spacing and breaching geometry play a major role in multiple inlet stability theory.

Using passive acoustics for long-term, continuous measurements of fish biodiversity in estuarine systems

Assessing the biodiversity of underwater habitats can be challenging; traditional sampling methods do not record all fish species, and are often conducted intermittently. As a result, fish diversity, ecosystem health, and resulting conservation decisions are often inferred through incomplete “snapshots” in time. Passive acoustic recordings can be conducted with high spatiotemporal resolution, and can provide data on species of ecological and economic importance that are missed by traditional sampling. This information is vital to understanding fish behavior, including when and where certain species are spawning, which is key to habitat conservation. We investigated the use of soundscapes as a tool to monitor fish biodiversity on oyster reefs in Pamlico Sound, NC, by coupling soundscape surveys with traditional biodiversity sampling. Fish vocalizations were detected in the soundscape especially at night when traditional biodiversity sampling would not normally occur, and during short periods of activity which may be missed by periodic sampling. In addition, soundscape composition changed over time, and was related to changes in biological community composition. When coupled with traditional biodiversity sampling methods, soundscape monitoring may provide a more complete understanding of spatiotemporal patterns in fish biodiversity and ecosystem health, which will inform future habitat conservation efforts in coastal ecosystems.

Using passive acoustics for long-term, continuous measurements of fish biodiversity in estuarine systems

Assessing the biodiversity of underwater habitats can be challenging; traditional sampling methods do not record all fish species, and are often conducted intermittently. As a result, fish diversity, ecosystem health, and resulting conservation decisions are often inferred through incomplete “snapshots” in time. Passive acoustic recordings can be conducted with high spatiotemporal resolution, and can provide data on species of ecological and economic importance that are missed by traditional sampling. This information is vital to understanding fish behavior, including when and where certain species are spawning, which is key to habitat conservation. We investigated the use of soundscapes as a tool to monitor fish biodiversity on oyster reefs in Pamlico Sound, NC, by coupling soundscape surveys with traditional biodiversity sampling. Fish vocalizations were detected in the soundscape especially at night when traditional biodiversity sampling would not normally occur, and during short periods of activity which may be missed by periodic sampling. In addition, soundscape composition changed over time, and was related to changes in biological community composition. When coupled with traditional biodiversity sampling methods, soundscape monitoring may provide a more complete understanding of spatiotemporal patterns in fish biodiversity and ecosystem health, which will inform future habitat conservation efforts in coastal ecosystems.