Ecological Specifications and TPCs for Macroinvertebrates in Reaches - - PowerPoint PPT Presentation

Ecological Specifications and TPCs for Macroinvertebrates in Reaches of the Crocodile River within the Kruger National Park

Sithole Hendrik1, Todd Colleen2 & Thirion Christa3

1 South African National Parks; 2 Independent Freshwater Ecological Consultant; 3 Department of Water and Environmental Affairs

Introduction

• South Africa a water scarce country (Lööv, 2002)
• SA heavily utilizes water resources (mostly from rivers) for socio-economic

needs (Walmsley et al. 1999)

• Common socio-economic activities in rivers = water abstractions,

impoundments and chemicals/nutrient addition

• Such activities result in altering river ecosystems (Kleynhans, 1996; Goetsch & Palmer, 1997 Kefford

et al. 2005)

• Water abstraction → Reduce water flow

→ Impact inverts. preferring fast flowing water → Ineffectively flush away chemicals/ nutrients

• Impoundments → restrict migration of inverts. through

the catchment

• Additional chemicals/nutrients → Affect inverts. preferring high quality

water (natural quantities of chemicals/nutrients)

• Socio-economic are challenge to environmental agencies
• Environmental agencies Reactions → Developed methods

monitor river conditions (e.g. Standardized sampling methods - SASS ; Ecological Reserves, etc.)

• Macroinvertebrate Gaps
• Develop & state preferable conditions for these river

ecosystems

• Develop limitation/tolerance to degradations

Introduction cont.

Objectives

• Determine the ecological status (present vs. reference

conditions) of reaches of Crocodile River within KNP

• Develop ecological objectives (EcoSpecs) for each reach
• Set TPCs for these EcoSpecs

Legend:

• Sampling Sites

— Rivers

Southern KNP

Study Site

Lwakahle

Study Site cont.

Reach 1 Reach 3 Reach 2

Lowveld Ecoregion level 1 Lebombo Uplands Ecoregion Level 1 Sampling Sites

Ecoregion Level 2 Ecoregion Level 2

Legend:

Study Site cont.

River Characteristics Vicinity Human Activities Reach 1 River Bed: Sand Dominated Little Riparian Vegetation Sugar Cane Farming Lodging Reach 2 River Bed: Bedrock Dominated Riparian Vegetation Settlement Livestock Reach 3 River Bed: Cobble Dominated Riparian Vegetation Sugar Cane Farming Lodging Reach 4 River Bed: Sand Dominated Riparian Vegetation Sugar Cane Farming Lodging Reach 5 River Bed: Bedrock Dominated Little Riparian Vegetation Sugar Cane Farming Lodging Table 1: Present Habitat Conditions of Reaches in Crocodile River

Methodology

• 1. Ecological Status
• Determined reference conditions of each reach

→ Historical data (from mid 1990s – SASS) → Expert knowledge

• Determined Present Ecological Category of each reach

→ Macroinvertebrate Response Assessment Index model (MIRAI) → MIRAI Categories – From A (no deviation from reference conditions) to F (extremely modified) → MIRAI Identifies – Most influential driver (Flow, Habitat, Water Quality)

• 2. EcoSpecs (Ecological Objectives)
• Used Ecological Category (from MIRAI)
• Used SASS indices (Score & ASPT Values)
• Selected Indicator Taxa (Frequency of occurrence, sensitivity to:

water flow; water quality & substratum composition)

• 3. TPCs
• Set TPCs per objective (determining when EcoSpecs are in danger
• f not being maintained)

Methodology cont.

Results

Reach 1 Reach 2 Reach 3 Reach 4 Reach 5 Ecological Category (%) C (74.9) C (76.2) C (74.0) C/D (61.8) C (70.2) SASS5 score 102 - 160 114 105 - 190 53 - 60 60 -123 ASPT value 5.1 - 6.2 6.3 5.0 - 5.8 4.4 - 5.5 4.6 - 5.9 Table 2: Current Ecological Conditions of Reaches in Crocodile River

Table 3: Indicator Taxa of Reaches in Crocodile River Reaches 1 2 3 4 5 V Hab. WQ Tricorythidae FF C M

• Elmidae

MF C M

• Heptageniidae

MF C H

• Atyidae

V M

• Coenagrionidae

V L

• Libellulidae

MF C L

• Hydropsychidae

>2spp. FF C H

• Gomphidae

G L

• FF = velocity of > 0.6m/s; C = Cobble substratum; M = Moderate Water

Quality; MF = velocity of 0.3 - 0.6m/s; H = High Water Quality; V = Vegetation; L = Low; G = Gravel-Sand-Mud

Results cont.

Table 4: Ecological Categories of Reaches in Crocodile River

ECOLOGICAL CATEGORY DESCRIPTION SCORE (% OF TOTAL) A Unmodified, natural. 90-100 B Largely natural with few modifications. A small change in natural habitats and biota may have taken place but the ecosystem functions are essentially unchanged. 80-89

C Moderately modified. A loss and change of natural habitat and biota have

• ccurred

but the basic ecosystem functions are still predominantly unchanged. 60-79

D Largely modified. A large loss of natural habitat, biota and basic ecosystem functions have

• ccurred.

40-59 E Seriously modified. The loss of natural habitat, biota and basic ecosystem functions are extensive. 20-39 F Critically/Extremely modified. Modifications have reached a critical level and the system has been modified completely with an almost complete loss of natural habitat and biota. In the worst instances the basic ecosystem functions have been destroyed and the changes are irreversible. 0-19

Results cont.

• Ecological Category C = Moderately modified. A loss and

change (21– 40%) of natural habitat and biota have occurred but the basic ecosystem functions are still predominantly unchanged.

• MIRAI shows water quality being the most impacted driver

throughout the five river reaches – Water Quality → nutrients, chemicals

Results cont.

Table 5: Recommended EcoSpecs and TPCs of Crocodile River Reach 1 Reach 2 Reach 3 Reach 4 Reach 5 Ecological Category (%) C (62 – 78) C (62 – 78) C (62 – 78) C/D (58 – 62) C (62 – 78) Ecological Category TPC ↓ 66% ↓ 68% ↓ 65% ↓ 60% ↓ 64% SASS5 score > 120 > 110 > 130 > 50 > 110 SASS5 score TPC ↓ 125 ↓ 115 ↓ 35 ↓ 55 ↓ 115 ASPT value > 5.4 > 6.0 > 5.0 > 5.0 > 5.0 ASPT value TPC ↓ 5.5 ↓ 6.1 ↓ 5.1 ↓ 5.1 ↓ 5.1 Key Indicator taxa 5 4 6 3 4 Key Indicator taxa TPC 3 missing 3 missing 2 missing 2 missing 2 missing

Recommendations.

Conclusion

• Very new ideas
• Will be tested and adjusted through time and learning

(Strategic Adaptive Management) Sponsorship: Kruger Marathon Club Thank you