Impacts of Climate change on the aquatic ecosystem in Great Bear - - PowerPoint PPT Presentation

K.L. Howland, C.P. Gallagher, E. Smith, K. Adair, L. Chavarie, Y. Janjua,

• D. Leonard, C. Podemski, R.F. Tallman, and W.M. Tonn

Impacts of Climate change on the aquatic ecosystem in Great Bear Lake, Canada

2

1 3 4 2 ALASKA

CANADA

Deline

Grey Goose Lodge/ Subsistence Fishing Neiland Bay Lodge Great Bear Lodge Trophy Lodge

Mine remediation site Mine exploration site Great Bear Lake Great Bear River

Local Fisheries‐ Traditional Ecological Knowledge

Environment, human uses and related stressors

Stressor GBL

Climate change

Major/ Change in Ice Free period (almost 3 weeks in 30 years) No direct major impact on fisheries yet

Water level

No

Pollution / Water quality

No, Well Controlled

Mining

No, not now

Commercial fisheries

No

Sport fisheries

Minor (C&R)

Tourism

No

Transport

No

(Janjua et al., unpublished)

Objectives

1. Address knowledge gaps regarding the Great Bear Lake ecosystem and the relationships of different ecosystem components to fisheries production

• Water quality
• Benthic invertebrates
• Zooplankton
• Nearshore terrestrial invertebrates

2. Establish community-based monitoring sites near Déline to assess seasonal and annual changes in water quality and invertebrate indicators 3. Assess impacts of climate change on Great Bear Lake ecosystem and possible effects on harvested fish

Methods ‐ Study Area

Tirato (Smith Arm) 2016 Kwit la (McTavish Arm) 2014 Tugacho (Dease Arm) 2015

Sahtu (Great Bear Lake)

Tirato (Keith Arm) 2012 Turili McVicar Arm 2013

Methods ‐ Ecosystem Sampling Design

Inshore (0‐2 m) Littoral (3‐20 m) Pelagic‐profundal (21‐50 m) Pelagic‐profundal (51‐100 m) Pelagic‐deep profundal (100+ m)

McVicar Arm (2013)

Depth Zone Water quality Zooplankton (plankton net) Benthic Inverts (Kick, Ponar grab) Fishing (gill nets) 0-2 m

 

Seine only 3-20 m

  

Bottom 21-50 m

  

Bottom/ Surface 51-100 m

  

Bottom/ Mid/ Surface 100+ m

  

Bottom/ Mid/ Surface

Composition, Abundance, Biomass Composition, Abundance, Biomass

Composition, Abundance, Biomass, Demographics

Temp, Chla, DO, pH, Tubidity, Conductivity

Community‐based monitoring sites

Off shore (60 m depth) temperature array; zooplankton; benthic invertebrates Nearshore benthic/ terrestrial invertebrates

X

Deline Keith Arm

Epilimnion Metalimnion Hypolimnion

Water Quality (temperature)

3‐20 m 21‐50 m 51‐100 m 100+ m

Keith Arm (2012) McVicar Arm (2013)

0‐2 m

Water Quality ‐ Thermocline

(Johnson 1975 JFRBC)

Epilimnion Metalimnion Metalimnion Hypolimnion

Water Quality (chlorophyll a)

3‐20 m 21‐50 m 51‐100 m 100+ m Keith Arm (2012) McVicar Arm (2013) 0‐2 m

Zooplankton Densities by Depth

Leptodiaptomus sicilis Limnocalanus macrurus X Senecella calaniodes Daphnia sp.

Species composition similar to earlier studies on Great Bear lake

10 20 30 40 50 60 70 80 90 100 Red (0-2 m) Yellow (3-20 m) Green (21-50 m) Purple (50-100 m) Blue (>100 m) Average frequency (%) Sampling strata Platyhelminthes Nematoda Annelida Mollusca Malacostraca Copepoda Ostracoda Arachnida Insecta

Benthic invertebrate community composition Keith Arm 2012

Kick Net Ponar Grab

5 10 15 20 25 30 35 40 45 Red (0-2 m) Yellow (3-20 m) Green (21-50 m) Purple (51-100 m) Blue (100+ m) Number of taxonomic groups in a sample Sampling strata

Kick Net

Benthic invertebrate diversity Keith Arm 2012

Ponar Grab

Benthic invertebrate abundance Keith Arm 2012

100 200 300 400 500 600 700 800 900 1000 Red (0-2 m) Yellow (3-20 m) Green (21-50 m) Purple (51-100 m) Blue (100+ m) Number of aquatic invertebrates in a sample Sampling strata

Kick Net Ponar Grab

Summary

• Sampling of invertebrates show variation in abundance by depth and

distance from shore

• Preliminary results on water quality and other ecosystem components

suggest shifts towards increased temperatures, stratification and possibly increased production at lower trophic levels over last 50 y

• climate related?
• need for continued monitoring to look at spatial and interannual

variability

Further work

• Complete sorting and identification: zooplankton, 2013

benthic invertebrates

• Examine patterns in distribution, abundance, demographics
• f fish, invertebrates > relationship to each other, abiotic

variables, historical data ‐ changes over time

• Investigate possibility of use of coring to reconstruct past

changes in lake temperature and productivity

• Data will contribute to ecosystem and fish population

models as it becomes available.

• Years 1 and 2 completed in a 5 year cycle:
• Continue in McTavish Arm (summer 2014)
• Continue seasonally comprehensive community‐based

monitoring close to Deline

Thank You! Mahsi Cho!

• NWT Cumulative Impacts Monitoring Program
• Sahtu Renewable Resources Board
• Deline Renewable Resources Council
• Deline Lands and Finance Corporation
• GNWT Renewable Resources Deline
• DFO Hay River, Yellowknife & Inuvik
• Polar Continental Shelf Project
• Natural Sciences and Engineering Research Council
• Canadian Circumpolar Institute
• Traditional Knowledge, Deline: Paul Modeste, Douglas Baton, John Tutcho,

George Kenny, Morrıs Modeste, Joseph Blondın, Jr., and Alfred Tanıton; community researchers Michael Neyelle & Mavis Baton

• Field Work 2012: Deline -Darren Kenny, Bobby Modeste, Allison Tatti, Gerald

Tutcho, Archie Vitale; DFO Winnipeg - Dave Boguski, Kristin Hynes

• Field Work 2013: Deline –Chris Yukon, Archie Vitale, Allison Tatti, Morris

Betsidea, Isodore Betsidea; DFO Winnipeg - Kristen Adair

• Invertebrate analyses: Erica Smith & Lyla Witschi