Inferring organic content of beach sand from color

Abstract

Relative organic content in sediment is an important determinant of ecological processes, but it can be difficult to quantify in the field. Here, we present evidence that relative organic matter content of sand may be inferred from relative coloration. For 50 sand samples collected from a beach on Long Island, Antigua, West Indies, we characterized sand color intensity (brightness) using image analysis of standardized photographs and measured percent organic matter lost on ignition with dry combustion. A linear regression provided evidence for a strong negative relationship between brightness and organic content; darker-colored sand contained more organic matter. Inferring organic content from color may provide a simple way to make field-based qualitative assessments of an important parameter in beach habitats.

Full text

Caribbean Naturalist
1
A.S. Maurer and S.P. Stapleton
2021 No. 80
CARIBBEAN NATURALIST
2021 No. 80:1–6
Inferring Organic Content of Beach Sand from Color
Andrew S. Maurer1,2,* and Seth P. Stapleton2,3
Abstract - Relative organic content in sediment is an important determinant of ecological
          
         
sand samples collected from a beach on Long Island, Antigua, West Indies, we character-
          
-
sion provided evidence for a strong negative relationship between brightness and organic
content; darker-colored sand contained more organic matter. Inferring organic content from

parameter in beach habitats.
Introduction
          
     


-


 
to organic matter because it provides resources needed to support life. As such, or-

organic matter offers nutrients that are important for plant growth, and processes


             -
    

         -


       

its distribution at their sites. Assessing sand organic content most often entails the
1
 2       3  
         
*


Caribbean Naturalist
A.S. Maurer and S.P. Stapleton
2021 No. 80
2
      -
 
 

-


          

     

           
      -


darker sand should have higher organic content. Relative sand color can be in-

       

-

      
management decision-making at beaches where sea turtles nest.
Methods
             
Antigua, a barrier island located northeast of mainland Antigua, West Indies
-
           
           

and egg-hatching success rates of Eretmochelys imbricata   

-



of the egg chamber and scooped outward into the surrounding sand, these impacts
         
           
         

  

Caribbean Naturalist
3
A.S. Maurer and S.P. Stapleton
2021 No. 80
          
changes 
  -

           -

  
-
          

and reweighed them.
 
-

-


 


Results

      
       
-
bP < 0.001; R2



Caribbean Naturalist
A.S. Maurer and S.P. Stapleton
2021 No. 80
4



Discussion
     
R2

       
-


of the sand-color spectrum. The residuals of the linear regression were greater for
  
          -
     

           
      

 
-
      


   -



  
   
   -
  -
   
    
P <
0.001, R2    
shaded area represents the
  
    
   

   -
land, Antigua, West Indies.

Caribbean Naturalist
5
A.S. Maurer and S.P. Stapleton
2021 No. 80
       


-



     
        
            
          



-
locating to lighter sand, it is often suggested that relocation sites match original nest



 
          
         
         
    

Acknowledgments
        
      
          

Literature Cited
 -





           
          




Caribbean Naturalist
A.S. Maurer and S.P. Stapleton
2021 No. 80
6

Caretta caretta-

-

-
  

-
ico: Importance of beach slope to nest-site selection in the Mississippi barrier islands.

           

Sargassum
     

   -
-

       
-



            

           




      


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