Thursday, June 27, 2013

Continued work on the Roe-Jan

We continued our efforts on the Roe Jan on Tuesday, but we did not find any additional ammocoetes or any adult lampreys. We attempted to sample where lamprey have been found before but thunderstorms and tides made that impossible. However, we did sample upriver and did not find any more ammocoetes. In addition to ammocoetes we also collect other samples and data. Below is a picture of a kick sample preserved in alcohol.
Kick samples are exactly what they sound like. A sturdy net is placed along the stream bed and then the individual holding the net kicks and stamps materials just upstream of the net. Invertebrates kicked up or disturbed drift into the net and are captured there. Samples like these allow us to determine what invertebrates may be present, which gives us information on habitat quality and habitat types that maybe available. In addition, it helps to build our understanding of the community in which these organisms live. Although the sample looks like a mess of leaves and sand we then pick out the invertebrates and ID them to the lowest level possible (usually genus).


Determining the genus of an insect can take an exceedingly long time as there are many species in the Northeast alone. For instance, in North America there are ~650 dragonfly and damselfly species (~5,500 species worldwide) belonging to 12 genera, often distinguished by microscopic details. This is considered a very small group and relatively easy to differentiate. Other groups, like flies (with ~120,000 species worldwide), are so large keying an individual may take up to an hour or more.


How long will it take to key out the above individuals? Actually not long, both of these appear to be relatively common. The smaller is a badly damaged mayfly (Ephmeroptera) and the larger is likely a common stonefly (maybe Plecoptera:Perlidae:Agnetina) .

Tuesday, June 25, 2013

Roe-Jan

We are finally back out on the water after long delays from rain, travel, and rain again. This week we went to the Roeliff Jansen Kill to look for lamprey. The Roe-Jan (as it is affectionately known) is a cool water stream on the east shore of the Hudson, an hour south of Albany. It is unusual because it is one of the few cold water streams that enters the Hudson, and supports abundant trout fisheries. When we first arrived it was thundering loudly and rain was coming down. However, when the rain settled down we left the car and found out that the 17-year cicadas were out in force in the forest.



As soon as the rain stopped and the sun peeked through, the cicadas started singing again, LOUDLY. Felt like a late afternoon in August, not a Monday towards the end of June. They are beautifully colored with orange wings and bright red eyes. They were everywhere: flying from tree to tree, littering the ground, and flopping exhausted into the stream. We began our fieldwork shortly thereafter and just before nightfall we found this guy:


A sea lamprey ammocoete! Finally! An ammocoete is the larval stage of a sea lamprey. Like most other fish, lamprey have a larval stage which is quite different from the adult. However, unlike most fish lamprey larvae are the majority of the life cycle of the animal and spend their time buried in sediments in streams. Ammocoetes are often very rare (as any person who has looked for them can tell you) but they can be amazingly abundant (>100 animals per square meter). Although previous work has shown that lamprey are present in the Roe-Jan, this is the first record I know that comes from as far upriver as we found it.

We look forward to finding more lampreys this summer and will be sure to post more pictures as we do.