Fish health changes in Lake Okaro, New Zealand: effects of nutrient remediation, season or eutrophication?

Abstract

The purpose of this investigation was to measure the in situ health of selected biota with respect to a large-scale application of an aluminiumamended zeolite (Z2G1) in Lake Okaro, New Zealand. We hypothesized that, based on previous laboratory toxicity testing, the Z2G1 application would have minimal or no significant health effects on lake fauna. To test this hypothesis, two sampling events were timed around the Z2G1 application to examine the health of two finfish species (Oncorhynchus mykiss and Gobiomorphus cotidianus) and crayfish (Paranephrops planifrons). Additionally, the same species were sampled from the neighbouring Lake Rerewhakaaitu in order to delineate seasonal and lake-specific effects. A general lack of aluminium accumulation in animal tissues following the application indicated that Z2G1-derived aluminium was not readily bioavailable. An unexplained osmoregulatory disturbance, indicated by increased blood plasma ion concentrations in Lake Okaro trout, was observed following the application, but could not be directly attributed to Z2G1 exposure. Changes in fish haematology over time and between lake populations were interpreted as physiological responses to seasonal changes in lake conditions. Using a broad range of specific and non-specific endpoints it was concluded that there were no obvious negative impacts on fish health resulting from Z2G1 exposure.

Variations of Food Web Structure and Energy Availability of Shallow Lake with Long‐Term Eutrophication: A Case Study from Lake Taihu, China

“…Nutrient enrichment causes an intensification of primary production and typically leads to dramatic changes in aquatic ecosystems . Many studies have measured the loss of biodiversity and variation in populations during the eutrophication process , but ecological degradation at the ecosystem‐level has received less attention. However, the ecosystem‐level response integrating the variation in all biological activities within ecosystems is critical for understanding the dynamics of ecosystem structure and function .…”

Maintenance of Fish Health in Aquaculture: Review of Epidemiological Approaches for Prevention and Control of Infectious Disease of Fish

“…Appropriate analyses can provide valid measures of incidence and prevalence of disease in particular area [ 73 ]. Its advantages include information better in quality, it is faster and cheaper to collect information than passive surveillance [ 74 ].…”

Preface: Lake restoration: an experimental ecosystem approach for eutrophication control

“…They include examining its potential eco-toxicological effects on fish health (Landman & Ling, 2010), zooplankton and phytoplankton composition (Ö zkundakci et al, 2010b) and freshwater crayfish (Paranephrops planifrons) (Parkyn et al, 2010). The remaining two papers examine nutrient dynamics, specifically those in the hypolimnion of the water column (Ö zkundakci et al, 2010c) and at the sediment-water interface (Gibbs & Ö zkundakci, 2010), including consideration of how the modified zeolite influenced these dynamics.…”