To study horseshoe crab Limulus polyphemus spawning behavior and migration over a large-spatial extent （〉100 km）, we arrayed fixed station radio receivers throughout Delaware Bay and deployed radio transmitters and...To study horseshoe crab Limulus polyphemus spawning behavior and migration over a large-spatial extent （〉100 km）, we arrayed fixed station radio receivers throughout Delaware Bay and deployed radio transmitters and archival tags on adult horseshoe crabs prior to their spawning season. We tagged and released 160 females and 60 males in 2004 and 217 females in 2005. The array covered approximately 140 km of shoreline. Recapture rates were 〉70% with multi-year recaptures. We categorized adult age by carapace wear. Older females tended to spawn earlier in the season and more frequently than young females, but those tendencies were more apparent in 2004 when spawning overall occurred earlier than in 2005 when spawning was delayed possibly due to decreased water temperatures. Timing of initial spawning within a year was correlated with water temperature. After adjusting for day of first spring tide, the day of In＇st spawning was 4 days earlier for every 1 degree （℃） rise in mean daily water temperature in May. Seventy nine % of spawning occurred during nighttime high tides. Fifty five % of spawning occurred within 3 d of a spring tide, which was slightly higher than the 47% expected if spawning was uniformly distributed regardless of tidal cycle. Within the same spawning season, males and females were observed spawning or intertidally resting at more than one beach separated by 〉5 kin. Between years, most （77%） did not return to spawn at the same beach. Probability of stranding was strongly age dependent for males and females with older adults experiencing higher stranding rates. Horseshoe crabs staging in the shallow waters east of the channel spawned exclusively along the eastern （N J） shoreline, but those staging west of the channel spawned throughout the bay. Overall, several insights emerged from the use of radio telemetry, which advances our understanding of horseshoe crab ecology and will be useful in conserving the Delaware Bay horseshoe crab population and habitats展开更多
Many studies have demonstrated that some of the activities of people can disturb nesting and foraging birds, particularly along coasts and estuaries. Some managers respond to human disturbance of sensitive species by ...Many studies have demonstrated that some of the activities of people can disturb nesting and foraging birds, particularly along coasts and estuaries. Some managers respond to human disturbance of sensitive species by closing beaches, but most have stewards monitor and restrict access to beaches or portions of beaches. Yet little is known about the type of visitor or their perceptions of beach stewards. This paper explores the general acceptance of beach stewards and their role in conservation of red knots </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">Calidris</span></i> <i><span style="font-family:Verdana;">canutus</span></i> <i><span style="font-family:Verdana;">rufa</span></i><span style="font-family:Verdana;">),</span></span><span style="font-family:Verdana;"> other shorebirds, and horseshoe crabs </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">Limulus</span></i> <i><span style="font-family:Verdana;">polyphemus</span></i><span style="font-family:Verdana;">) </span></span><span style="font-family:Verdana;">along the Delaware Bay (New Jersey) beaches by interviewing 279 visitors during the stopover period. While most people came to see the shorebird and horseshoe crab spectacle (60%), many came for the scenery, tranquility, and recreation. Just over half of the people interviewed said that the stewards were helpful (58%), although most of those that answered this question later said that they provided conservation value (86%), but only 40% said they relied on the stewards for information. On a Likert rating scale of 1 to 5 (the highest value), the mean rating for whether it was important for stewards to be present was 3.87 ± 0.09, and the rating for the presence of stewards who can provide information was 3.71 ± 0.11. In contrast, protection of shorebirds was rated a mean of 4.79 ± 0.04. There were significant visitor type differences in how important stewards were, but not in the importance of stewards who can provide information. Fishermen, recreationists, and people coming for scenery and tranquility rated the presence of stewards higher than those visitors who were interested in either shorebirds or crabs (or both). Ratings also differed significantly as a function of age and gender;older adults and females rated characteristics higher than did people under 30 years and males. Information needs identified by stewards are also discussed. These data can be used by the managers developing a strategy for conservation of shorebirds and other species sensitive to disturbance, and for the implementation of an effective stewardship program.展开更多
基金Support Program, New Jersey Fish Game & Wildlife, and Delaware Department of Natural Resources and Environmental Control
文摘To study horseshoe crab Limulus polyphemus spawning behavior and migration over a large-spatial extent （〉100 km）, we arrayed fixed station radio receivers throughout Delaware Bay and deployed radio transmitters and archival tags on adult horseshoe crabs prior to their spawning season. We tagged and released 160 females and 60 males in 2004 and 217 females in 2005. The array covered approximately 140 km of shoreline. Recapture rates were 〉70% with multi-year recaptures. We categorized adult age by carapace wear. Older females tended to spawn earlier in the season and more frequently than young females, but those tendencies were more apparent in 2004 when spawning overall occurred earlier than in 2005 when spawning was delayed possibly due to decreased water temperatures. Timing of initial spawning within a year was correlated with water temperature. After adjusting for day of first spring tide, the day of In＇st spawning was 4 days earlier for every 1 degree （℃） rise in mean daily water temperature in May. Seventy nine % of spawning occurred during nighttime high tides. Fifty five % of spawning occurred within 3 d of a spring tide, which was slightly higher than the 47% expected if spawning was uniformly distributed regardless of tidal cycle. Within the same spawning season, males and females were observed spawning or intertidally resting at more than one beach separated by 〉5 kin. Between years, most （77%） did not return to spawn at the same beach. Probability of stranding was strongly age dependent for males and females with older adults experiencing higher stranding rates. Horseshoe crabs staging in the shallow waters east of the channel spawned exclusively along the eastern （N J） shoreline, but those staging west of the channel spawned throughout the bay. Overall, several insights emerged from the use of radio telemetry, which advances our understanding of horseshoe crab ecology and will be useful in conserving the Delaware Bay horseshoe crab population and habitats
文摘Many studies have demonstrated that some of the activities of people can disturb nesting and foraging birds, particularly along coasts and estuaries. Some managers respond to human disturbance of sensitive species by closing beaches, but most have stewards monitor and restrict access to beaches or portions of beaches. Yet little is known about the type of visitor or their perceptions of beach stewards. This paper explores the general acceptance of beach stewards and their role in conservation of red knots </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">Calidris</span></i> <i><span style="font-family:Verdana;">canutus</span></i> <i><span style="font-family:Verdana;">rufa</span></i><span style="font-family:Verdana;">),</span></span><span style="font-family:Verdana;"> other shorebirds, and horseshoe crabs </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">Limulus</span></i> <i><span style="font-family:Verdana;">polyphemus</span></i><span style="font-family:Verdana;">) </span></span><span style="font-family:Verdana;">along the Delaware Bay (New Jersey) beaches by interviewing 279 visitors during the stopover period. While most people came to see the shorebird and horseshoe crab spectacle (60%), many came for the scenery, tranquility, and recreation. Just over half of the people interviewed said that the stewards were helpful (58%), although most of those that answered this question later said that they provided conservation value (86%), but only 40% said they relied on the stewards for information. On a Likert rating scale of 1 to 5 (the highest value), the mean rating for whether it was important for stewards to be present was 3.87 ± 0.09, and the rating for the presence of stewards who can provide information was 3.71 ± 0.11. In contrast, protection of shorebirds was rated a mean of 4.79 ± 0.04. There were significant visitor type differences in how important stewards were, but not in the importance of stewards who can provide information. Fishermen, recreationists, and people coming for scenery and tranquility rated the presence of stewards higher than those visitors who were interested in either shorebirds or crabs (or both). Ratings also differed significantly as a function of age and gender;older adults and females rated characteristics higher than did people under 30 years and males. Information needs identified by stewards are also discussed. These data can be used by the managers developing a strategy for conservation of shorebirds and other species sensitive to disturbance, and for the implementation of an effective stewardship program.
