Beach erosion and geochemical factors: Influence on spawning success of horseshoe crabs (Limulus polyphemus) in Delaware Bay

1988 ◽  
Vol 99 (3) ◽  
pp. 325-332 ◽  
Author(s):  
M. L. Botton ◽  
R. E. Loveland ◽  
T. R. Jacobsen
Keyword(s):  
Delaware Bay ◽  
Limulus Polyphemus ◽  
Beach Erosion ◽  
Horseshoe Crabs ◽  
Geochemical Factors ◽  
Spawning Success

scholarly journals DELAWARE BAY MISPILLION INLET ENVIRONMENTAL RESTORATION PROJECT

2018 ◽  
pp. 8
Author(s):  
Peter Kotulak
Keyword(s):  
Environmental Control ◽  
Tidal Flow ◽  
Hurricane Sandy ◽  
Delaware Bay ◽  
Limulus Polyphemus ◽  
Environmental Restoration ◽  
The North ◽  
North Side ◽  
Horseshoe Crabs ◽  
Red Knot

The Delaware Department of Natural Resources and Environmental Control (DNREC) has received grants from Hurricane Sandy funding to rehabilitate and improve environmental functionality and sustainability for areas along the Delaware Bay shoreline. The Mispillion Inlet Complex near Milford, Delaware was one of the projects selected due to its importance as habitat for both American Horseshoe Crabs (Limulus polyphemus) and shorebirds, specifically the threatened species Rufa Red Knot (Calidris canutus rufa). The complex includes the Mispillion River and Cedar Creek that connect at Mispillion Inlet and provide access for tidal flow and navigation into the Delaware Bay via federally-authorized and maintained channels. Efforts to stabilize Mispillion Inlet first occurred in 1859 when a 560-foot long timber pile jetty was constructed along the north side of the inlet. In 1908 a south jetty was constructed, and in subsequent years, several additional jetty extensions were made to a total length of about 5,800 feet. In 1985, the barrier spit separating Mispillion River and the Delaware Bay north of the inlet breached and was subsequently closed with a stone dike and sand fill. Two years later, the repaired area was breached again, followed by placement of more rock and sand.

scholarly journals Oyster aquaculture does not impede spawning beach access for Atlantic horseshoe crabs Limulus polyphemus

2020 ◽  
Vol 12 ◽  
pp. 81-90
Author(s):  
DM Munroe ◽  
TM Grothues ◽  
NE Cleary ◽  
J Daw ◽  
S Estrada
Keyword(s):  
Eastern Oyster ◽  
Delaware Bay ◽  
Limulus Polyphemus ◽  
Oyster Aquaculture ◽  
Horseshoe Crabs ◽  
Eastern Usa ◽  
Crab Abundance ◽  
Oyster Farm ◽  
Oyster Farms ◽  
And Behavior

Farms for eastern oyster Crassostrea virginica, which are commonly located along shallow estuarine shores of the eastern USA, use a range of farm equipment and require regular access to care for and harvest oyster livestock. In some cases, these farms are located in areas used by Atlantic horseshoe crabs Limulus polyphemus as they come ashore during spring to spawn. The sandy shores of the Delaware Bay host the largest spawning aggregations of this species in the world. Limited studies have examined interactions between horseshoe crabs and intertidal oyster farms, and concern has been raised about the horseshoe crab’s ability to traverse oyster farms to reach spawning habitat. This study examines potential farm interactions with horseshoe crabs in Delaware Bay during the 2018 and 2019 crab spawning season. Our studies included a range of experiments and surveys during high and low tide to observe crab abundance and behavior at rack-and-bag oyster farm and non-farm sites. In all cases, results indicated that crabs can successfully traverse rack-and-bag farms and reach spawning beaches. Crabs do not differentially use farm versus non-farm areas, and crab behavior is relatively unaltered by farm gear. These results provide important context for developing frameworks for managing ecological interactions among farms and wildlife species of concern.

New insights into the evolution of lateral compound eyes in Palaeozoic horseshoe crabs

2019 ◽  
Vol 187 (4) ◽  
pp. 1061-1077 ◽  
Author(s):  
Russell D C Bicknell ◽  
Lisa Amati ◽  
Javier Ortega-Hernández
Keyword(s):  
Convincing Evidence ◽  
Limulus Polyphemus ◽  
Phylogenetic Position ◽  
Compound Eyes ◽  
Crown Group ◽  
Widespread Occurrence ◽  
Eye Evolution ◽  
Stem Group ◽  
Lateral Eye ◽  
Horseshoe Crabs

Abstract Vision allows animals to interact with their environment. Aquatic chelicerates dominate the early record of lateral compound eyes among non-biomineralizing crown-group euarthropods. Although the conservative morphology of lateral eyes in Xiphosura is potentially plesiomorphic for Euarthropoda, synziphosurine eye organization has received little attention despite their early diverging phylogenetic position. Here, we re-evaluate the fossil evidence for lateral compound eyes in the synziphosurines Bunodes sp., Cyamocephalus loganensis, Legrandella lombardii, Limuloides limuloides, Pseudoniscus clarkei, Pseudoniscus falcatus and Pseudoniscus roosevelti. We compare these data with lateral eyes in the euchelicerates Houia yueya, Kasibelinurus amicorum and Lunataspis aurora. We find no convincing evidence for lateral eyes in most studied taxa, and Pseudoniscus roosevelti and Legrandella lombardii are the only synziphosurines with this feature. Our findings support two scenarios for euchelicerate lateral eye evolution. The elongate-crescentic lateral eyes of Legrandella lombardii might represent the ancestral organization, as suggested by the phylogenetic position of this taxon in stem-group Euchelicerata. Alternatively, the widespread occurrence of kidney-shaped lateral eyes in stem-group Xiphosura and stem-group Arachnida could represent the plesiomorphic condition; Legrandella lombardii eyes would therefore be derived. Both evolutionary scenarios support the interpretation that kidney-shaped lateral eyes are ancestral for crown-group Euchelicerata and morphologically conserved in extant Limulus polyphemus.

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