Surviving the big chill: overwintering strategies of aquatic and terrestrial insects.

The purpose of this paper is to describe the cold-hardiness of aquatic insects and to use the literature to compare physiological and behavioral strategies that aquatic and terrestrial insects use to cope with minimum winter temperatures. In sharp contrast to terrestrial insects, aquatic insects from seven different orders had limited ability to supercool and did so to temperatures of only −3 to −7°C. Inability to supercool may be due to inoculative freezing—the penetration of external ice crystals through pores or orifices of the insect's cuticle. Furthermore, our results suggest that terrestrial adult stages of aquatic insects may have greater capacity to supercool than aquatic stages of the same taxon. Our results and others' suggested that few aquatic species are freeze tolerant, and those that are appear to be restricted to the order Diptera. Consequently, behavioral avoidance of ice or the capacity to remain unfrozen while encased in ice may be particularly important for overwintering aquatic insects. Ecological implications of insect coldhardiness at the individual, population, and community level are discussed for both terrestrial and aquatic insects

Effects of an Ammonia-Rich Municipal Sewage Effluent on Iowa River Fauna Near Marshalltown, Iowa

The effect of the Marshalltown municipal sewage effluent on Iowa River water quality and fauna was evaluated from July 1976 through August 1977. The effluent contains high total ammonia and un-ionized ammonia concentrations due to ammonia-rich discharges from meat packinghouses. Dissolved oxygen, pH, temperature, total ammonia nitrogen, and un-ionized ammonia data were collected at.12 sampling stations extending 18 km downstream from the sewage effluent discharge. Wild fish collections were made by using electrofishing, seines, and hoopnets. Thirty-eight fish species were collected during the study. Channel catfish. (Ictalurus punctatus) and smallmouth bass (Micropterus dolomieus) were the most common gamefish. No consistent depression in wild fish diversity was seen below the sewage discharge point. Eight hundred thirty caged channel catfish were used in conducting 13 4-day field toxicityty tests at 5 different river stations. Only 2% mortality was observed. Macroinvertebrate diversity and density were determined by using artificial substrate samplers placed at 5 river stations during 2 3-week exposure periods in the summer of 1976. Macroinvertebrate diversity recovered 770-1550 m downstream from the sewage discharge point. The applicability of the EPA un-ionized ammonia criterion and the Iowa total ammonia nitrogen standard is evaluated in light of the findings from this study

Surviving the Big Chill: Overwintering Strategies of Aquatic and Terrestrial Insects

The purpose of this paper is to describe the cold-hardiness of aquatic insects and to use the literature to compare physiological and behavioral strategies that aquatic and terrestrial insects use to cope with minimum winter temperatures. In sharp contrast to terrestrial insects, aquatic insects from seven different orders had limited ability to supercool and did so to temperatures of only −3 to −7°C. Inability to supercool may be due to inoculative freezing—the penetration of external ice crystals through pores or orifices of the insect\u27s cuticle. Furthermore, our results suggest that terrestrial adult stages of aquatic insects may have greater capacity to supercool than aquatic stages of the same taxon. Our results and others\u27 suggested that few aquatic species are freeze tolerant, and those that are appear to be restricted to the order Diptera. Consequently, behavioral avoidance of ice or the capacity to remain unfrozen while encased in ice may be particularly important for overwintering aquatic insects. Ecological implications of insect coldhardiness at the individual, population, and community level are discussed for both terrestrial and aquatic insects

Climate Change and the World’s “Sacred Sea”—Lake Baikal, Siberia

Lake Baikal—the world\u27s largest, oldest, and most biotically diverse lake—is responding strongly to climate change, according to recent analyses of water temperature and ice cover. By the end of this century, the climate of the Baikal region will be warmer and wetter, particularly in winter. As the climate changes, ice cover and transparency, water temperature, wind dynamics and mixing, and nutrient levels are the key abiotic variables that will shift, thus eliciting many biotic responses. Among the abiotic variables, changes in ice cover will quite likely alter food-web structure and function most because of the diverse ways in which ice affects the lake\u27s dominant primary producers (endemic diatoms), the top predator (the world\u27s only freshwater seal), and other abiotic variables. Melting permafrost will probably exacerbate the effects of additional anthropogenic stressors (industrial pollution and cultural eutrophication) and could greatly affect ecosystem functioning

Lake-wide physical and biological trends associated with warming in Lake Baikal

Eutrophication and warming of lakes are occurring globally. Lake Baikal, a large ancient lake composed of three basins, has recently experienced benthic eutrophication at local sites and lake warming in the south basin. Here, we look for signals of warming and pelagic eutrophication across the entire lake using physical and biological data collected at a subset of 79 stations sampled ca. annually (1977–2003) during the period of summer stratification. Lake-wide, surface waters warmed 2.0 °C; and, consistent with this warming, the abundance of two warm-water, cosmopolitan zooplankton taxa increased between two (pelagic cladocerans) and 12-fold (Cyclops kolensis). C. kolensis increased throughout the lake, whereas cladocerans increased significantly only in the north basin. In contrast, abundance of the cold-water endemic copepod, Epischura baikalensis, that dominates the crustacean zooplankton community, did not change. With the exception of one coastal station in the north basin, there is no evidence of pelagic eutrophication. Although chlorophyll concentrations increased 46% lake-wide (0.82 to 1.20 μg/L), the increasing trend was significant only in the south basin. Surprisingly, mean Secchi transparency increased by 1.4 m lake-wide across the 26-year time series with significant deepening of water transparency occurring in the central and north basins. This suggests a decline in productivity in the north and middle basins, but an increase in the south basin. Taken together, these findings suggest that physical and biological changes associatedwithwarming have occurred in Lake Baikal, butwide-spread pelagic eutrophication in the lake\u27s three basins has not

Exploring patterns of recurrent melanoma in Northeast Scotland to inform the introduction a digital self-examination intervention

Peer reviewedPublisher PD

Rapid ecological change in the coastal zone of Lake Baikal (East Siberia): Is the site of the world\u27s greatest freshwater biodiversity in danger?

Ecological degradation of the benthic littoral zone is an emerging, urgent problem at Lake Baikal (East Siberia), the most species-rich lake on Earth. Within the last five years, multiple changes have occurred in the nearshore benthos where most of the lake\u27s endemic species reside. These changes include proliferation of benthic algae, deaths of snails and endemic sponges, large coastal wash-ups of dead benthic algae and macrophytes, blooms of toxin-producing benthic cyanobacteria, and inputs of industrial contaminants into parts of the lake. Some changes, such as massive coastal accumulations of benthic algae, are currently shared with the Laurentian Great Lakes (LGLs); however, the drivers of these changes differ between Lake Baikal and the LGLs. Coastal eutrophication from inputs of untreated sewage is causing problems at multiple sites in Lake Baikal, whereas in the LGLs, invasive dreissenid mussels redirect pelagic nutrients to the littoral substrate. At other locations in Lake Baikal, ecological degradation may have different causes including water level fluctuations and the input of toxic industrial contaminants. Importantly, the recent deterioration of the benthic littoral zone in both Lake Baikal and the LGLs has occurred while little change has occurred offshore. This highlights the necessity of monitoring both the littoral and pelagic zones of large lakes for assessing ecosystem health, change and conservation