Crustaceans as ecological indicators of metropolitan sandy beaches health

Ghost crabs have been widely used as a bio-indicator species of human impacts on sandy beaches to obtain reliable biological data for management and conservation purposes. Ghost crab population densities and individual sizes decline dramatically under human pressure. However, distribution within a beach and the factors that determine this distribution of ghost crabs is still an open question. These factors may provide valuable information for understanding human impacts on sandy beaches. Here we examine ghost crab burrows on 20 sandy beaches of South Carolina, USA under various levels of human impacts to understand the response in terms of spatial distribution of this species to human impacts. We also examine the burrow characteristics and environmental properties of the burrows to determine whether these factors alter burrow characteristics. We show that crabs on heavily impacted beaches altered their spatial distribution to mostly occupy the edges of impacted beaches. Further, this change in spatial distribution was influenced by the size distribution of the population on a beach (i.e. larger individuals occupy upper parts on the beaches). We also found that ghost crabs altered the morphology of their burrows on heavily impacted beaches. Ghost crabs create deeper, steeper and smaller burrows under human impacts. These patterns were also influenced by physical characteristics of the beach. Our results suggest that human impacts can directly influence the spatial distribution of ghost crab populations within a beach and therefore sampling at upper parts of the beaches overestimates the population density and individual sizes. Our results support the use of ghost crabs as indicator species in effective beach management, but suggest that assessments would benefit from examining the morphology and distribution of burrows as opposed to simply using burrow counts to assess the health of sandy shores.

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“…[15–17], mole crabs, Emerita spp. [18], sand beach coleoptera, Phaleria spp. [19] and ghost crabs, Ocypode spp.…”

Section: Introductionmentioning

confidence: 99%

Impacts of human disturbance on ghost crab burrow morphology and distribution on sandy shores

Gül

Griffen

2018

PLoS ONE

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“…Emerita brasiliensis, for example, is a species that tends to increase their occurrence from reflective to dissipative beaches next to swash zone (Defeo & Cardoso 2004). Spatial migration in a sandy beach could happen due to food distribution and temperature changes (Defeo & McLachlan 2005, Cardoso et al 2016. Even in the winter samples, there was a low variation on richness for both beaches.…”

Section: Discussionmentioning

confidence: 99%

“…In Brazil, Veloso et al (2006) performed an experiment comparing high urbanized beaches with lesser urbanized ones in the Rio de Janeiro state, where the beaches were classified into two distinct seasons (summer and winter). In that study it was possible to verify a drastic change in abundance of some crustacean species, such as Atlantorchestoidea brasiliensis (Dana 1853), which was completely absent in the highly urbanized beach sampled (Cardoso et al 2016). Machado et al (2017) performed a very similar study about human trampling comparing two beaches in the Rio de Janeiro state, one highly urbanized and another non-urbanized.…”

Section: Introductionmentioning

confidence: 99%

Human Trampling Effect on Benthic Fauna of Sandy Beaches With Different Intensities of Use in Rio De Janeiro, Brazil

Reis

Rizzo

2019

Oecol. Aust.

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About 75% of the world's shoreline is composed of beach environments. Among them, the sandy beach is a familiar environment and used for tourism and recreation. The organisms that live in these environments, as polychaetes, crustaceans and mollusks, are almost unknown by people because they live buried. Thus, many time people could cause damage to these organisms without their own knowledge. Trampling is one of the human-induced impacts to those organisms, destroying their bodies or even dispelling them. Focused on this behavior, this research aims to simulate trampling on two sandy beaches and to observe a real scenario of recreation on weekends and during the week during summer and winter seasons in the Rio de Janeiro state, Brazil. This study verified the changes occurring mainly in the faunal density of these two beaches with different intensities of use, in the predefined situations. Samples were collected during four months, on the second half of year, using simulated treatments and in another two months simple observation of the behavior of tourists was also performed. The simulated treatments did not cause significant changes in any collection except two. One of them was possibly a sampling artifact, which may be due to a low level of impact. The samples on the winter months also did not show significant changes, but the summer samples showed a large decrease in density of organisms during the weekend compared to during the week, probably related to the high intensity of human activity. As this study aimed to verify changes or impacts in organisms at up to 20 cm of depth, we concluded that only high impact activities could affect drastically the faunal density, as observed during the summer season at weekends on the study.

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“…), and sandy beach coleoptera (Phaleria spp.) (Cardoso et al, 2016;González et al, 2014;Schlacher et al, 2008;Sheppard et al, 2009).…”

Section: Implications For This Systemmentioning

confidence: 99%

“…Intensity of human disturbance on sandy beaches generally increases with human population size (Davenport & Davenport, 2006;Defeo et al, 2009;Halpern et al, 2008). The ecological impacts of this disturbance are commonly assessed using the population abundance and size structures of common macroinvertebrates such as clams (Defeo & de Alava, 1995;Schlacher, Thompson, & Walker, 2008;Sheppard, Pitt, & Schlacher, 2009), mole crabs and sand hoppers (Cardoso, Barboza, Skinner, & Cabrini, 2016), beetles (González, Yáñez-Navea, & Muñoz, 2014), and ghost crabs (Aheto, Asare, Mensah, & Aggrey-Fynn, 2011;Barros, 2001;Gül & Griffen, 2018aHobbs, Landry, & Perry, 2008;Lucrezi, Schlacher, & Robinson, 2009;Neves & Bemvenuti, 2006;Schlacher et al, 2016;Steiner & Leatherman, 1981;Wolcott & Wolcott, 1984).…”

Section: Introductionmentioning

confidence: 99%

Burrowing behavior and burrowing energetics of a bioindicator under human disturbance

Gül

Griffen

2019

Ecology and Evolution

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Bioindicator species are extensively used for rapid assessment of ecological changes. Their use commonly focuses on changes in population abundance and individual sizes in response to environmental change. These numerical and demographic shifts likely have behavioral and physiological mechanistic drivers that, if understood, could provide additional insights into the use of these species as bioindicators of habitat health. The Atlantic ghost crab, Ocypode quadrata, is a global bioindicator species of human disturbance on sandy shores. Individual size and population abundance of O. quadrata decline dramatically at sites with human disturbance, and the causes of this phenomenon remain unclear. Here, we test the hypothesis that individual and population‐level changes at disturbed sites reflect changes in burrowing behavior and energetics. Specifically, we examine whether or not the burrowing behavior (e.g., burrow fidelity and longevity) of O. quadrata changes because of human disturbance. We also examine energy required for burrowing by O. quadrata across different levels of human disturbance. We show that O. quadrata have the highest burrow fidelity and longevity at sites with low level of human impact, and weakest burrow fidelity and longevity at pristine sites. O. quadrata reduce the burrowing energy allocation by manipulating the burrow dimension and increasing the burrow longevity even under low levels of human disturbance. Overall, this study shows that human disturbances not only change the behavior of organisms, but also shift energetic balance. Our results support the use of a bioenergetic approach to better understand how human disturbances influence natural populations, and the specific use of this approach with this bioindicator species.

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Crustaceans as ecological indicators of metropolitan sandy beaches health

Cited by 54 publications

References 51 publications

Impacts of human disturbance on ghost crab burrow morphology and distribution on sandy shores

Impacts of human disturbance on ghost crab burrow morphology and distribution on sandy shores

Human Trampling Effect on Benthic Fauna of Sandy Beaches With Different Intensities of Use in Rio De Janeiro, Brazil

Burrowing behavior and burrowing energetics of a bioindicator under human disturbance

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