Unfortunately I didn’t have a camera capable of video, otherwise I could demonstrate the bizarre, unidirectional movement of these juvenile snails that looked as if a 1×1-m carpet was moving over the benthos of the river.
Tag Archives: Osa Peninsula
Lutijanus novemfasciatus
The black snapper/Pacific cubera snapper I mentioned as a new Osa species is pictured below. These were caught in Rio Madrigal, near the La Leona field station in Corcovado National Park. Look at the little teeth (third picture), robust shape, stunning color, superficial resemblance to families such as Cichlidae and Centrachidae.
Sirena to La Leona
A half-way resting point from the Sirena field station to La Leona.
Leaf-input to tropical streams
Rio Claro receives a substantial amount of leaf-input from surround trees, particularly in the dry season. Organic matter processing and the importance of these inputs are little study in tropical streams, especially in comparison with temperate systems, where we know that excluding this vital energy source dramatically changes in-stream communities, which can then affect terrestrial, riparian ecosystems. Given the great abundance of invertebrates, like shrimp, that are likely shredders and biofilm-grazing snails, it’s likely that tropical streams operate similar to temperate streams… Anyway, here’s some leaf packs.
 |
 |
Rio Claro, Sirena
Some images from Rio Claro, Corcovado National Park. Hiking up this stream to sample fish again or otherwise research stream ecology is a must for me.
A Costa Rican Mallow
My best guess is that this flower is from a mallow (Malvaceae) because of its bizarrely stalked reproductive parts. This was common along the banks of Rio Claro, Corcovado National Park.
Invertebrates, underwater
These glass shrimp (I can’t recall the species) are extremely common in Osa streams, as are the Neritid snails below.
I had to take these photos from the surface, since I don’t have an underwater camera, but I think it would be extremely cool to see some underwater, macro-photography (like that over at Myrmecos) of macroinvertebrates.
Pargo in Rio Claro
Snapper (Lutjanidae – mostly Lutijanus spp.) inhabit near-ocean reaches of streams throughout Costa Rica. They are generally marine, but will often feed in freshwater and it seems that they dominate the large, fish predator group in Costa Rican streams as a result. There are at least three common species in the Osa Peninsula, where these were found, including Lutijanus novemfasciatus (the black snapper or Pacific cubera snapper). Last year, we caught L. novemfasciatus in Rio Madrigal and recorded a new species for Osa.
I’m unsure of the identification of those below, but they were photographed in Rio Claro, near the Sirena Field Station in Corcovado National Park
Sunset Moonrise
As the sun set at the mouth of Rio Sirena, the moon came up from behind us.
Patrolling ant
