Author: tomahawkcitizenscience

Training

Training day 2018

tomahawkcitizenscience

It was great to see all the new faces on our Feb 26th training day! Our teams are now a mix of experienced citizen scientists and new students learning the ropes 🙂

It was a bit chilly out there, but after a brief introduction and having the scene set by Dr. Marc Schallenberg from the University of Otago, the students got stuck into their regular monitoring. And what a day to begin- with Cyanobacteria still in bloom at Site 1 (Domain Hall).. It was instantly obvious why we were all there and how important it is to get a handle on the health of Tomahawk Lagoon.

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Results at a glance (compared with previous sampling date)-

Site 1 Algal bloom still active.

Chlorophyll a very high in both lagoons

E. coli  increased and all Sites exceeded guidelines

Nitrogen greatly decreased from 2 Feb, but still exceed guideline values at S1-3

DRP (dissolved reactive phosphorus) lower at S4-5 and higher at S1-2. All exceed guideline values

Dissolved Oxygen S1 very low, S2 low – this makes it hard for critters and fish to survive

Check out our Results page for the most recent results and graphs

Sampling Trips

Invertebrate Sampling 12/09/2017

tomahawkcitizenscience

What a cold, grey day! But that didn’t stop the teams from Otago Girls’ and John McGlashan heading out into the chilly lower lagoon to collect pelagic (in the water column) and benthic (in/on the sediment) samples of macroinvertebrates from their sites.

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What can these tell us about the health of the Lagoon? Freshwater invertebrate taxa (groups of species) have been found to have different tolerance levels to pollution such as excessive nutrients, so their presence or absence (and in some cases abundance) is often used in rivers to give an idea of the probable pollution level and therefore the water quality. Scientists call this the Macroinvertebrate Community Index (MCI), and it works by using a number or ‘score’ that scientists have assigned to each taxa based on their tolerance, and this score is simply added up for all of the taxa found.
It’s slightly more complex in Tomahawk Lagoon unfortunately, being a brackish lake that’s often quite salty from seawater, so it is unknown just how accurate these macroinvertebrates will be at indicating water quality.. But it’s worth having a dig around to see.
We can also use our macroinvertebrate findings to give us insights into the foodweb in the lagoon- we are basically finding what the fish eat. We’ll build up a foodweb based on our sampling trips and post it here soon.. stay tuned 🙂