March, JG, and CM Pringle. 2003. Food web structure and basal resource utilization along a tropical island stream continuum, puerto rico. Biotropica 35 (1) (MAR): 84-93.
Abstract:
Tropicals treamf ood webs are thought to be based primarilyo n terrestriarl esources( leaf litter) in small forested
headwatesrt reamsa nd algalr esourceisn largerw, iders treamsI. n tropicali slands treamst, he dominantc onsumeras re
often omnivorousfr eshwatesrh rimpst hat consumea lgae,l eaf litter,i nsects,a nd others hrimpsW. e useds tablei sotope
analysist o examine( 1) the relativei mportanceo f terrestriaal nd algal-basedfo od resourcest o shrimpsa nd other
consumersa nd determine( 2) if the relativeim portanceo f thesef ood resourcecs hangeda longt he streamc ontinuum.
We examined8 15N and 813Cs ignatureos f leaves,a lgae,m acrophytesb, iofilm,i nsects,s nails,f ishes,a nd shrimpsa t
threes ites (300, 90, and 10 m elev.)a longt he Rio EspirituS anto,w hichd rainst he CaribbeanN ationalF orestP, uerto
Rico. Isotopes ignatureos f basalr esourcews ered istincta t all sites.R esultso f two-source6 13Cm ixingm odelss uggest
that shrimpsr eliedm oreo n algal-basedca rbonr esourcetsh an terrestrialldye rivedr esourceas t all threes itesa longt he
continuum.T his studys upportso therr ecentf indingsi n tropicals treamsd, emonstratintgh ata lgal-basedre sourceas re
very importantt o streamc onsumers,e ven in small forestedh eadwaters treams.T his study also demonstratetsh e
importanceo f doing assimilation-baseadn alysis( i.e., stablei sotope or trophicb asis of production)w hen studying
food webs.