The distribution of Heterotrissocladius oliveri Saether (Diptera: Chironomidae) in Lake Michigan

Fifty one chironomid species were identified from 504 samples collected at depths ranging 8 to 267 m in Lake Michigan, U.S.A. Heterotrissocladius oliveri Saether occurred in 32% of these samples and had an average abundance of 22 m −2 which was similar to other estimates from the Great Lakes. Maximum average lake-wide density was at 30 to 60 m (41 m −2 ). At depths ≥60 m, H. oliveri was the dominant chironomid species comprising 75% of total Chironomidae. The substrate preference of H. oliveri differed within each depth regime considered: at 30–60 m, 2–3 ϕ; at 60–120 m, 3–5 ϕ, 7–9 ϕ; and at 120–180 m, 6–8 ϕ. Abundance was notably reduced at all depths in substrates characterized as medium silt (5–6 ϕ). On a lake-wide basis, the distribution pattern suggested H. oliveri was most numerous from 30 to 60 m along the southwestern, eastern, and northern shorelines and at 60–120 m depths along the southern and eastern shorelines. Increased abundance in the South Basin was concurrent with evidence of increased sedimentation at 60 to 100 m. However, in several other areas of the lake, high densities were associated with medium to very fine sands relatively free of silts and clays. This observation suggested occurrence of H. oliveri was minimally affected by sediment type.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42871/1/10750_2004_Article_BF00008856.pd

Camera traps : the research paparazzi

The use of cameras to monitor wildlife is commonplace; however, little is known of the effectiveness of different camera technologies for the detection of mammals. We compared the detection success of three different camera systems, a passive infrared (IR) system, an active IR and a constant video camera, alongside a trapping grid of Elliott and cage traps to determine their effectiveness at detecting mammals at multiple locations in the Otways National Park, Victoria, Australia (n = 160 events; 40 &plusmn; 23 [SD] events per night). Species detected and detection rates differed between methods (&chi;2 = 57.95, df = 2, p &lt; 0.0001). Only house mice (Mus musculus) were detected by camera and traditional trapping techniques. Camera systems alone detected foxes (Vulpes vulpes) and a koala (Phascolarctos cinereus), while traditional traps captured bush rats (Rattus fuscipes), agile antechinus (Antechinus agilis) and a brush-tailed possum (Trichosurus vulpecula) which were not detected by the camera systems. Assuming that the video camera detected all mammals at the camera trap, the passive IR system detected almost all mammals detected by the video and it detected significantly more species than the active IR system. The choice of method will ultimately depend on the species of interest, logistics and the study site, and may substantially influence the results of a study.<br /

Waves affect predator-prey interactions between fish and benthic invertebrates.

Little is known about the effects of waves on predator–prey interactions in the littoral zones of freshwaters. We conducted a set of mesocosm experiments to study the differential effects of ship- and wind-induced waves on the foraging success of littoral fish on benthic invertebrates. Experiments were conducted in a wave tank with amphipods (Gammarus roeseli) as prey, and age-0 bream (Abramis brama, B0), age-0 and age-1 dace (Leuciscus leuciscus, D0 and D1) as predators. The number of gammarids suspended in the water column was higher in the wave treatments compared to a no-wave control treatment, especially during pulse waves mimicking ship-induced waves in comparison to continuous waves mimicking windinduced waves. The resulting higher prey accessibility in the water column was differently exploited by the three types of predatory fish. D0 and D1 showed significantly higher foraging success in the pulse wave treatment than in the continuous and control treatments. The foraging success of D0 appears to be achieved more easily, since significantly higher swimming activity and more foraging attempts were recorded only for D1 under the wave treatments. In contrast, B0 consumed significantly fewer gammarids in both wave treatments than in the control. Hence, waves influenced predator–prey interactions differently depending on wave type and fish type. It is expected that regular exposure to ship-induced waves can alter littoral invertebrate and fish assemblages by increasing the predation risk for benthic invertebrates that are suspended in the water column, and by shifting fish community compositions towards species that benefit from waves