One of my two students for this year’s LSAMP REU is sampling and documenting the fish communities within the rivers at Las Cruces as an extension of a previous student of mine’s project (David’s). David had discovered four species, Bryconamericanus terrabensis, Brachyrhaphis terrabensis, Rhamdia laticauda, and Trichomycterus striatus, and he had presented his work at AFS. Interestingly, at Bry. terrabensis and T. striatus, have not been reported as occurring above 1,000 meter above sea level in the literature, and he thought this could be due to (1) undersampling and reporting and/or (2) recent changes in the distribution of these fishes, possibly due to climate change. One way to find out—continued monitoring. And, hence, Ahmi’s interest.
Ahmi may be employing three survey methods (visual surveys via snorkeling, seining, and minnow trapping) and sample along the entire elevational gradient within the Las Cruces property (1,000 – 1,400 masl).
Here, Ahmi practices visual surveys—a 5-10 minute zig-zag, calling out letters that represent the most likely fishes. The water is cool and turbid, making it difficult to complete, unlike some of the rivers, like Rio Madrígal, Rio Claro and Rio Nuevo, I surveyed using similar methods years ago on the Osa Penninsula.
Next, Ahmi and Zane practice seining the same pool; the current and steep, slippery banks present some difficulty, but they do catch a few.
Seining is hard work!
Some catch from the sample, including Bry. terrabensis.
Two catfish are distributed throughout Las Cruces streams. The long-whiskered catfish (Rhamdia rogersi) is present in Río Java and several small streams, including Quebrada Culvert and the upstream Quebrada Culebra. The other, the Pencil Catfish (Trichomycterus striatus), I have only caught in Río Java.
Here, minnow traps were used to collect crabs and both species of catfish were caught as by-catch.
Additionally, while we collected the pencil catfish in 2013 and subsequent years, it doesn’t look like I ever published any images—so here are a few old images of Trichomycterus.
Some sheepshead (Sparidae, Archosargus probatocephalus) at Three Sisters Springs in Crystal River, Florida. Their common name comes from the set of incisor-like teeth visible from the front, and molar-like teeth visible in the open mouth.
Lepomis auritus (Centrachidae) in Crystal River and Rainbow Springs State Park, Florida.
It was surprising to see abundant sunfish in the brackish, tidally influenced, portion of Crystal River, and I was excited to see that I didn’t know which species it was on-sight. I think these are red-breasted sunfish, a species that may be found in Ohio, but relatively rarely, especially compared to bluegill (L. macrochirus) and green sunfish (L. cyanellus). In fact, the collection of Ohio fish that was used in Vertebrate Zoology at Kent State didn’t include this species.