Does ‘You Are What You Eat’ Apply to Mangrove Grapsid Crabs?

Abstract

In tropical mangroves, brachyuran crabs have been observed to consume high percentages of leaf litter production. However, questions concerning their ability to assimilate this low-quality food remain, as stable isotope analysis of C and N does not seem to support assimilation. Individuals of the common eastern Australian mangrove grapsid Parasesarma erythodactyla feeding on a mangrove leaf litter or mangrove+microphytobenthos diet developed a significantly higher hepatosomatic index than those with access to only sediment. Lipid biomarker analysis and feeding experiments using 13C and 15N-enriched mangrove leaf litter confirmed rapid assimilation of mangrove C and N by P. erythodactyla. Eight-week feeding experiments utilizing three food types (mangrove leaf litter, microphytobenthos and prawn muscle) established different food-specific trophic discrimination values (Δδ13C and Δδ15N) that are significantly different from those commonly applied to mixing model calculations. The mean Δδ13C(crab-mangrove) of +5.45‰ was close to the mean and median literature values for grapsid-mangrove pairs in 29 past studies (+5.2±1.8‰ and +5.6‰, respectively), suggesting that this large discrimination may generally be characteristic of detritivorous grapsid crabs. Solutions from the IsoConc mixing model using our determined trophic discrimination values suggest significantly higher and dominant contributions of mangrove C to the diet than those based on the global mean trophic discrimination values. Our results reaffirm the physiological capacity for and important mediating role of grapsid crabs in processing low-quality mangrove C in tropical estuaries, and caution against the use of global trophic discrimination values in stable isotope analysis of food-web data, especially those involving detritivores. While recent studies have questioned the trophic significance of mangrove detritus in coastal food chains, the contribution of this productive carbon source needs to be re-assessed in the light of these data.

Dietary Dependence of Predatory Arthropods on Volant Aquatic Insects in Tropical Stream Riparia

“…Secondly, laboratory feeding trials have shown that trophic fractionation can be highly specific to the pairing of food and consumers, and in some extreme cases can vary by more than 5‰ in Δ 13 C or Δ 15 N when different combinations of arthropod consumers and food sources are involved ( e.g., Oelbermann & Scheu , Bui & Lee , Carvalho et al . ).…”

Temporal variability of carbon and nutrient burial, sediment accretion, and mass accumulation over the past century in a carbonate platform mangrove forest of the Florida Everglades

“…Although mangroves only cover between 138,000 and 152,000 km 2 [ Giri et al ., ; Spalding et al ., ], these forested wetlands are of great value for their contributions to environmental, societal, and economic functions around the globe. In addition to providing habitat for numerous fauna and supporting food webs (directly and indirectly) [ Bui and Lee , ; Kristensen et al ., ; Nagelkerken et al ., ], natural resources for human communities [ Walters et al ., ] along with stabilization and protection of shorelines from tsunamis and storm surge [ Alongi et al ., ; Costanza et al ., ], these wetlands make a substantial contribution to the global carbon budget [ Bouillon et al ., ; Breithaupt et al ., ; Dittmar et al ., ; Donato et al ., ; Duarte et al ., ; Jennerjahn and Ittekkot , ; Mcleod et al ., ]. When looking specifically at the soil component of the budget, the quantitative research can be broadly categorized according to whether the focus is the organic carbon (OC) standing stock [ Adame et al ., ; Donato et al ., , 2012; Kauffman et al ., ] or the rate of OC burial [ Breithaupt et al ., , and references therein; Chmura et al ., ; Mcleod et al ., ].…”

Development of the integrated fuzzy analytical hierarchy process with multidimensional scaling in selection of natural wastewater treatment alternatives

“…Specifically, MDS was developed as a technique for measuring the distance among psychological stimuli, which are presented as points in geometric space. The method now has extensive applications in different fields, e.g., ecology Bui and Lee (2014). It utilizes similarities between pairs of stimuli to identify a psychological distance between those stimuli.…”

“…Creative, cost effective and environmental friendly ways are therefore required to explore approaches to manipulating water pollution (Tsaur et al, 2002). Stabilization pond, constructed wetland and other ecological land treatment systems are the centralized sewage treatment options, and ecological engineering that are employed to reduce water pollution and developed as sustainable ecosystems that have both human and ecological values (Mitsch, 2012). They have been used in both developed and developing countries, due to the general good performance in maintenance, minimal fossil fuel consumption (Crites et al, 2014;Kivaisi, 2001) as useful options for climate change adaptation.…”