Mary Freeman
S. Thomas Purucker
Catherine M. Pringle
Marcia Snyder
2016
<p><span>Freshwater shrimps are an important biotic component of tropical ecosystems. However, they can have a low probability of detection when abundances are low. We sampled 3 of the most common freshwater shrimp species, </span><i>Macrobrachium olfersii, Macrobrachium carcinus</i><span>, and </span><i>Macrobrachium heterochirus</i><span>, and used occupancy modeling and logistic regression models to improve our limited knowledge of distribution of these cryptic species by investigating both local- and landscape-scale effects at La Selva Biological Station in Costa Rica. Local-scale factors included substrate type and stream size, and landscape-scale factors included presence or absence of regional groundwater inputs. Capture rates for 2 of the sampled species (</span><i>M. olfersii</i><span> and </span><i>M. carcinus</i><span>) were sufficient to compare the fit of occupancy models. Occupancy models did not converge for </span><i>M. heterochirus</i><span>, but </span><i>M. heterochirus</i><span> had high enough occupancy rates that logistic regression could be used to model the relationship between occupancy rates and predictors. The best-supported models for </span><i>M. olfersii</i><span> and </span><i>M. carcinus</i><span> included conductivity, discharge, and substrate parameters. Stream size was positively correlated with occupancy rates of all 3 species. High stream conductivity, which reflects the quantity of regional groundwater input into the stream, was positively correlated with </span><i>M. olfersii</i><span> occupancy rates. Boulder substrates increased occupancy rate of </span><i>M. carcinus</i><span> and decreased the detection probability of </span><i>M. olfersii.</i><span> Our models suggest that shrimp distribution is driven by factors that function at local (substrate and discharge) and landscape (conductivity) scales.</span></p>
application/pdf
10.1086/684486
en
Society for Freshwater Science
Using occupancy modeling and logistic regression to assess the distribution of shrimp species in lowland streams, Costa Rica: Does regional groundwater create favorable habitat?
article