Assessing Anthropogenic and Natural Impacts on Ghost Crabs (Ocypode quadrata) at Cape Hatteras National Seashore, North Carolina

Hobbs, Carl H.; Landry, Cynthia B.; Perry, James E.

doi:10.2112/07-0856.1

Cited by 47 publications

(48 citation statements)

References 29 publications

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“…However, Turra et al (2005) and da Rosa & Borzone (2008) also found Ocypode on beaches with coarse sands. Ghost crabs may migrate back toward the dunes and burrow there for shelter during storms (Hobbs et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Coupling between macrofauna community structure and beach type: a deconstructive meta-analysis

Defeo¹,

McLachlan²

2011

Mar. Ecol. Prog. Ser.

104

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Species richness and abundance of macrofauna on sandy shores increase from microtidal reflective to macrotidal dissipative beach conditions. However, no attempt has been made to deconstruct these patterns. Using information on the macrofauna from 63 microtidal sandy beach surveys in South America, we deconstructed the community to discriminate among taxonomic groups, supralittoral and intertidal forms, and groups with different feeding habits and development modes. We also separated the effects of development mode and beach zone (intertidal vs. supralittoral) at the species level and scaled body size to density estimates. Total species richness decreased towards reflective beaches, but this trend was less marked in crustaceans than in molluscs or polychaetes. Supralittoral air-breathing crustaceans increased in richness and abundance from dissipative to reflective conditions, a reverse trend to that seen in intertidal crustaceans. Development modes (species with direct development and with planktonic larvae) showed the same response to beach type as the community as a whole. Filter feeders, scavengers and deposit feeders showed the same trend, but the latter were scarce or absent on reflective beaches. Zone was more important than either development or feeding modes in determining individual species responses to beach type. Body size decreased and density increased from reflective to dissipative beaches, suggesting that smaller forms are more sensitive to harsh conditions where density is lower, and hence there is less scope for biological interactions in reflective beaches. The deconstruction approach provided insights into the relationships between life cycle characteristics and richness and abundance patterns and the relative importance of environmental variables in beach ecology.

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Section: Discussionmentioning

confidence: 99%

Coupling between macrofauna community structure and beach type: a deconstructive meta-analysis

Defeo¹,

McLachlan²

2011

Mar. Ecol. Prog. Ser.

104

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“…Several studies on sandy beaches have been carried out worldwide using the abundance of ghost crab burrows to assess the levels of anthropogenic disturbance. Significant differences between the number of ghost crab burrows in urban and non-urban beaches have been found in many others [12][13][14][15][16][17][18][19][20][21]. In all these studies, the number of burrows had a negative association with the levels of human disturbance in the observed beaches.…”

Section: Resultsmentioning

confidence: 93%

Number of ghost crab burrows does not correspond to population size

Silva¹,

Calado

2013

Open Life Sciences

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Ghost crabs are distributed worldwide on sandy beaches, and several studies have associated the number of ghost crab burrows with the levels of anthropogenic impacts on the beaches under study. However, our results show that the use of ghost crab Ocypode quadrata burrows to assess levels of anthropogenic impacts on sand beaches may not be accurate, as previously thought, because the number of burrows does not represent an estimate of the population size. In addition, we propose three hypotheses to explain the extremely low number of individuals/number of burrows ratio: the "secret chamber", the "multiple openings", and the "one crab, several burrows" hypotheses. We also observed an unusual sex ratio.

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“…Varios estudios que han comparado la abundancia de O. quadrata entre playas perturbadas y conservadas, han arribado a la conclusión de que las actividades humanas conllevan a la disminución de la abundancia de esta especie (Steiner & Leatherman, 1981;Turra, Gonçalves, & Denadai, 2005;Blankensteyn, 2006;Neves & Bemvenuti, 2006;Araújo et al, 2008;Hobbs, Landry, & Perry, 2008;Souza et al, 2008). El presente estudio ha demostrado que el disturbio humano puede impactar negativamente otros atributos de las poblaciones como el crecimiento y la sobrevivencia de los individuos.…”

Section: Discussionunclassified

Efectos del disturbio humano sobre la dinámica poblacional de Ocypode quadrata (Decapoda: Ocypodidae) en playas del Caribe mexicano

Ocaña

Navarrete

Carrillo

et al. 2016

RBT

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Effects of human disturbance on the population dynamics of Ocypode quadrata (Decapoda: Ocypodidae) in beaches of the Mexican Caribbean. The ghost crab Ocypode quadrata is a relevant species in the Western Atlantic beaches, and has been proposed as an indicator of human impact in these ecosystems. Eventhough some studies have covered various aspects of its natural history, no evaluations on the effects of human disturbance on its population dynamics have been made. This work compared the abundance, growth, and mortality of O. quadrata in two disturbed beaches (Aventuras and Majahual) and two preserved beaches (Xcacel and Puerto Angel) from the Mexican Caribbean. For this, nine samplings were made on each beach (every two to three months) between March 2013 and November 2014. Crabs were collected manually by three people, during the night first hours and for one hour, and a total area of 9 000 m 2 per beach. The crabs were measured, weighed, and separated into three groups: juvenile, male and female; while abundance was estimated by the number of collected crabs, and growth parameters were estimated using length frequencies. A total of 1 047 crabs were sampled in the four beaches; a higher crab abundance was found in the preserved beaches, but significant differences were only found between Puerto Angel and Majahual (Tukey, p<0.05). The adultjuvenile ratio was 1:1 in Xcacel and Aventuras, while in Majahual, more juveniles than adults were collected; and Puerto Angel had more adults than the juveniles. The size structure at Xcacel ranged from 4-32 mm, but in the rest of the beaches the minimum size was 5 mm. The maximum size at Aventuras, Majahual and Puerto Angel were 27 mm, 25 mm and 30 mm, respectively. The modal progression analysis of length's pooled data, revealed the presence of at least two groups of ages in all beaches. For all beaches, individuals smaller than 10 mm length were collected in almost all sampling months, indicating a continuous recruitment throughout the year. The length-weight relationship of the ghost crab was found isometric in the two preserved beaches, and negative allometric at the two impacted beaches. Crabs from Puerto Angel showed the highest body condition (Tukey, p<0.05). K-values ranged from 0.6-0.97/year and L∞ from 29.0 mm to 33.6 mm with higher values for the two preserved beaches. The highest mortality values were found in Xcacel and Aventuras. In the disturbed beaches, the destruction of the dunes, the mechanical cleaning and the removal of organic matter, seem to be the main causes that lead to a low abundance of crabs, their slower growth and higher mortalities. However, in the best preserved beaches, biological interactions appear to be the most important aspects in regulating the population dynamics of this species. These results supported the information that the ghost crab is a good indicator of human disturbance, and its population changes were clearly measurable and comparable among protected and impacted beaches; these results are also relevant for the man...

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Assessing Anthropogenic and Natural Impacts on Ghost Crabs (Ocypode quadrata) at Cape Hatteras National Seashore, North Carolina

Cited by 47 publications

References 29 publications

Coupling between macrofauna community structure and beach type: a deconstructive meta-analysis

Coupling between macrofauna community structure and beach type: a deconstructive meta-analysis

Number of ghost crab burrows does not correspond to population size

Efectos del disturbio humano sobre la dinámica poblacional de Ocypode quadrata (Decapoda: Ocypodidae) en playas del Caribe mexicano

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