Freshwater Decapod Diversity and Conservation in Central America and the Caribbean

Wehrtmann, Ingo S.; Ramírez, Alonso; Pérez‐Reyes, Omar

doi:10.1007/978-3-319-42527-6_9

Cited by 11 publications

(3 citation statements)

References 138 publications

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“…* represent the original model predictions in Lake (2000). 2013, Wehrtmann et al 2016. The family Atyidae includes 4 species (Atya lanipes, A. innocuous, A. scabra, and Micratya poeyi), Palaemonidae includes 5 species (Macrobrachium acanthurus, M. carcinus, M. faustinum, M. crenulatum, and M. heterochirus), and Xiphocarididae includes 1 species (Xiphocaris elongata).…”

Section: Study Systemmentioning

confidence: 99%

When the rainforest dries: Drought effects on a montane tropical stream ecosystem in Puerto Rico

et al. 2020

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Global climate change predictions include decreased precipitation and more frequent droughts in many world regions. In the aseasonal wet tropics, predicting potential impacts is particularly challenging because droughts are rare and therefore poorly understood. In 2015, the Caribbean islands experienced the most severe drought within the past 5 decades. Here, we use this extreme event as an opportunity to assess how tropical stream ecosystems draining the Luquillo Experimental Forest (LEF) in Puerto Rico respond to severe drought. During 2015, precipitation was 45% lower than the long-term (1975-2016) average for the LEF, resulting in a 54% reduction in stream discharge. After 5 mo of declining discharge (April-August 2015), one branch of our focal study stream system became a series of isolated pools and a few riffle-type runs, while the other branch had greatly reduced flow between its pools. Concentrated biotic activity within pools resulted in elevated and highly-variable nutrient (5.1-12.1 lg PO 4 32-P/L; 12.9-57.2 lg NH 4 1-N/L; 80.0-160.0 lg NO 3 2-N/L) and specific conductance (95-114 lS/cm) levels among pools. However, the algal standing crop was 14Â lower than the previous 15-y average despite increases in nutrient levels, reflecting intense grazing pressure of insect and shrimp consumers, potentially due to decreased pool volume. Higher nutrient levels in stream pools did increase biofilm productivity, and at the peak of the drought daily fluctuations in dissolved oxygen ranged from ∼1.0 to 6.5 mg/L. Significantly-higher riparian inputs of organic matter (7.6Â the longterm average) occurred during a 15-d period in May. The drought caused a general increase in macroinvertebrate density, with collector-gatherers and some grazer taxa increasing significantly at the peak of the drought, but taxonomic richness did not change. Omnivorous shrimp abundance increased slightly in response to decreased stream flow in one branch of our focal stream. Our study highlights the marked effects of severe droughts on neotropical streams in the wet tropics, with large effects on basal resources and consequent changes in trophic dynamics. Ultimately, our findings underline the need for a whole-ecosystem perspective to understand how streams respond to increased frequencies of extreme events associated with climate change.

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Section: Study Systemmentioning

confidence: 99%

When the rainforest dries: Drought effects on a montane tropical stream ecosystem in Puerto Rico

et al. 2020

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“…larvae during laboratory trials. If land use change or other anthropogenic activities in the tropics (see Wehrtmann et al, 2016) reduce crab populations, there would be implications for the food web dynamics and ecosystem functions of these streams.…”

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confidence: 99%

Neotropical freshwater crabs (Decapoda: Pseudothelphusidae) shred leaves

et al. 2020

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Freshwater crabs are macroconsumers that are commonly found in Neotropical headwater streams that may play a key role in energy flow and nutrient cycling in detrital food webs. Although studies have examined the feeding habits of trichodactylid crabs, little is known of this behavior in pseudothelphusid species, and specifically whether they actually consume leaf material. We conducted three nine-day laboratory trials with pseudothelphusid crabs (Ptychophallus tumimanus (Rathbun, 1898)) and leaves (Koanophyllon pittieri) to investigate whether crabs shred leaves. We hypothesized that leaf mass loss would be faster with crabs present relative to control tanks with only leaves. Leaf mass loss was significantly higher (p < 0.001) in tanks with crabs (0.49 ± 0.07 g, mean ± 1 SD) compared to control tanks (0.31 ± 0.05 g). We observed crabs manipulating, shredding, and consuming leaves, with leaf fragments and egesta present in tanks with crabs but not in control tanks. Their consumption and egestion activity may affect nutrient availability and transformation by stimulating microbial activity during leaf breakdown and converting coarse particulate organic matter (CPOM) to fine particulate organic matter (FPOM). Therefore, freshwater crabs need to be considered when studying energy flow and nutrient cycling in detrital food webs of Neotropical headwater streams.

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“…Although researchers have studied the taxonomy, phylogeny, and conservation of neotropical freshwater crabs (e.g. Cumberlidge et al, 2014;Lara, Wehrtmann, Magalhães, & Mantellato, 2013;Poettinger, Klaus, & Schubart, 2016;Wehrtmann, Ramírez, & Pérez-Reyes, 2016), fewer studies have addressed their ecological roles. However, there have been some recent feeding ecology studies on trichodactylid crabs in South America (e.g.…”

Section: Introductionmentioning

confidence: 99%

Freshwater crabs (Decapoda: Pseudothelphusidae) increase rates of leaf breakdown in a neotropical headwater stream

et al. 2020

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Freshwater crabs are the largest macroconsumers in many neotropical headwater streams, but few studies have examined their roles in ecosystem processes such as leaf litter breakdown. As omnivorous macroconsumers, freshwater crabs affect multiple trophic levels. They may directly increase leaf breakdown through fragmentation and consumption or indirectly decrease breakdown by consuming other macroinvertebrates, including shredders and detritivores. In a headwater stream in Monteverde, Costa Rica, we conducted an in‐stream experiment with 40 enclosures to quantify the effects of pseudothelphusid crabs on both leaf breakdown and macroinvertebrate colonisation of leaves. Half of the enclosures were randomly selected to contain two crabs (mean carapace width = 30 mm) and half were controls without crabs. We sampled mixed leaf packs from the enclosures on days 11, 19, 28, 34, and 42. We found the leaves of one species (Koanophyllon pittieri) almost completely decomposed by day 28 in both treatments (crab versus no crab). The other two leaf species (Meliosma idiopoda, Quercus brenesii) composed the remaining leaf mass at the end of the experiment. At 42 days, enclosures with crabs had faster rates of leaf breakdown than those without crabs (with crabs: k = −0.020; without crabs: k = −0.016; p = 0.034). This suggests that the magnitude of direct leaf breakdown by crabs, due to fragmentation, consumption, or manipulation of leaves, was greater than any indirect effects on leaf breakdown via crab consumption of other leaf‐consuming species. Macroinvertebrate composition based on taxa abundances or biomasses did not significantly differ between treatments (ANOSIM; p = 0.73 and p = 0.65, respectively). Shredder and detritivore abundances and biomasses increased significantly through time (ANOVA; p ≤ 0.001), but there was no evidence of an effect of crab presence (p > 0.2), nor were there significant interactions between crab presence and time (p > 0.3). This is one of the first studies to quantify the effects of pseudothelphusid freshwater crabs on leaf breakdown rates. Our results suggest that these crabs can play a significant role in detrital processing in neotropical headwater streams. This study has also demonstrated that short‐term enclosure experiments are useful in measuring in‐stream effects of crab activity on leaf breakdown.

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Freshwater Decapod Diversity and Conservation in Central America and the Caribbean

Cited by 11 publications

References 138 publications

When the rainforest dries: Drought effects on a montane tropical stream ecosystem in Puerto Rico

When the rainforest dries: Drought effects on a montane tropical stream ecosystem in Puerto Rico

Neotropical freshwater crabs (Decapoda: Pseudothelphusidae) shred leaves

Freshwater crabs (Decapoda: Pseudothelphusidae) increase rates of leaf breakdown in a neotropical headwater stream

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