Jerry L. Kaster

Effect of rural highway runoff on stream benthic macroinvertebrates

Abstract The impact of rural highway runoff on benthic macroinvertebrate abundance and composition was studied in a southeastern Wisconsin, USA, stream during 1980-81. The study suggests minimal effect on stream macroinvertebrates by rural highway runoff from roadways of 7000–8000 vehicles per day traffic volume. Differences in mean annual numbers and biomass between the control (4155 m −2 , 10·5 g m −2 ) and the station receiving slight highway runoff (2611 m −2 , 5·2 g m −2 ), presumably resulted from slower current and siltation at the latter. The station which received the greatest amount of runoff had higher mean annual numbers (13 291 m −2 ) and biomass (62·2 g m −2 ) than the control. Increased current and better substratum were probably responsible for masking potential highway effects at this station. Another station with intermediate amounts of highway runoff had similar annual mean numbers (4642 m −2 ) and biomass (10·6 g m −2 ) to the control. Similar values for richness were found between stations. Pollution sensitive fauna were approximately half as abundant at the station with intermediate amounts of highway runoff, suggesting possible slight runoff influence.

Comparison of defecation rates of Limnodrilus hoffmeisteri Claparède (Tubificidae) using two different methods

The defecation rate of the tubificid oligochaete, Limnodrilus hoffmeisteri Claparéde was measured by using inverted and upright defecation chambers. Worms cultured using the upright method consistently produced larger amounts of feces (45 to 110%) than those in the inverted method (P < 0.01). The average defecation rate for the upright method was 0.69 ± 0.058 (95% CL) mg feces mg-1 dry weight h-1 compared with 0.41 ± 0.033 (95% CL) mg feces mg-1 dry weight h-1 for worms using the inverted method.

Feeding habits and dietary overlap of Naididae (Oligochaeta) from a bog stream

Feeding habits and dietary overlap of three species of naidid oligochaetes (Chaetogaster diastrophus, Dero digitata, Dero nivea) were studied during June 1982–December 1983 from a bog stream in Wisconsin, USA. Chaetogaster diastrophus primarily ingested diatoms, while D. digitata and D. nivea primarily ingested detritus. Dietary overlap was substantial (97–98%) between D. digitata and D. nivea using the dietary overlap coefficient. Dietary overlap between C. diastrophus and D. digitata was 58–62% and that between C. diastrophus and D. nivea was 51–55%. Dietary differences existed between the three species in the percentage of each major food type and diatom genera ingested, selective ingestion or avoidance of diatom genera and in the size classes (length and/or volume) of diatoms consumed. These data suggest temporal coexistence of these species may possibly be due to complex food resource partitioning, although in this habitat, C. diastrophus, D. digitata, and D. nivea did not exhibit concurrent peak abundances; thus, interspecific competition for food was minimized.

PHOSPHOLIPID PROFILING OF SEDIMENTS USING PHOSPHORUS-31 NUCLEAR MAGNETIC RESONANCE

A phosphorus-31 nuclear magnetic resonance method has been developed for the determination of aquatic sediment phospholipid profiles that may be generally applied to all soils and deposits containing viable cellular material. A method of scrubbing chloroform/methanol extracts with potassium acid phosphate overcomes adverse signal broadening from the mineral component, permitting eleven sediment phospholipids to be determined at the quantitative level.

Transverse Coastal Corridor: From Freshwater Lakes to Coral Reefs Ecosystems

Understanding the processes and mechanisms that determine coastal connectivity may help us to propose and establish more effective strategies for maintaining the environmental goods and services from coastal ecosystems. The eastern Yucatan Peninsula, from inland to sea range from: karstic freshwater lakes, brackish lagoons, estuarine coastal lagoons to reef lagoons. These ecosystems coalesced to form the largest and complex coastal ecosystems of the Yucatan Peninsula. The spatio-temporal structure of this complex ecosystem can be used as a model system to study connectivity processes through its hydrological, biogeochemical and ecological interactions. Based on its structure we propose a conceptual model, which we call the “Transverse Coastal Corridor” as a meaningful strategy for research, coastal development and conservation in the southeastern Yucatan Peninsula. The corridor includes the second largest freshwater karstic lake in Mexico, Laguna Bacalar; the largest estuarine-coastal lagoon, Chetumal Bay, the largest extant freshwater microbialite ecosystem and the structurally most complex coral reef ecosystem of the Mesoamerican Barrier Reef System. Physical, chemical and biological exchanges and interactions across the corridor of terrestrial, freshwater, marine environments drive a diverse and complex set of ecological processes that determine biodiversity and ecosystem functioning. We consider that the conceptual model of The Transverse Coastal Corridor may be more appealing to the different actors involved in the regional scale as it recognizes the particular biological and ecological characteristics of the interrelated ecosystems by seeking a balance from protection, management efforts, and sustainable use of the natural resources whilst preserving ecosystem functioning.