Ecological Specifications and TPCs for Macroinvertebrates in Reaches of the Crocodile River within the Kruger National Park Sithole Hendrik 1 , Todd Colleen 2 & Thirion Christa 3 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)
Introduction cont. • 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
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
Study Site Southern KNP Lwakahle Legend: • Sampling Sites — Rivers
Study Site cont. Ecoregion Level 2 Ecoregion Level 2 Reach 2 Reach 3 Reach 1 Legend: Sampling Sites Lowveld Ecoregion level 1 Lebombo Uplands Ecoregion Level 1
Study Site cont. Table 1: Present Habitat Conditions of Reaches in Crocodile River River Characteristics Vicinity Human Activities Reach 1 River Bed: Sand Dominated Sugar Cane Farming Little Riparian Vegetation Lodging Reach 2 River Bed: Bedrock Dominated Settlement Riparian Vegetation Livestock Reach 3 River Bed: Cobble Dominated Sugar Cane Farming Riparian Vegetation Lodging Reach 4 River Bed: Sand Dominated Sugar Cane Farming Riparian Vegetation Lodging Reach 5 River Bed: Bedrock Dominated Sugar Cane Farming Little Riparian Vegetation Lodging
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)
Methodology cont. 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 of not being maintained)
Results Table 2: Current Ecological Conditions of Reaches in Crocodile River 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
Results cont. 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 FF C H - - - - >2spp. � � � � 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 DESCRIPTION SCORE CATEGORY (% OF TOTAL) A Unmodified, natural. 90-100 B Largely natural with few modifications. A small change in natural habitats and biota may have 80-89 taken place but the ecosystem functions are essentially unchanged. C Moderately modified. A loss and change of natural habitat and biota 60-79 have occurred but the basic ecosystem functions are still predominantly unchanged. D Largely modified. A large loss of natural habitat, biota and basic ecosystem functions have 40-59 occurred. E Seriously modified. The loss of natural habitat, biota and basic ecosystem functions are 20-39 extensive. F Critically/Extremely modified. Modifications have reached a critical level and the system has 0-19 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.
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
Recommendations . Table 5: Recommended EcoSpecs and TPCs of Crocodile River Reach 1 Reach 2 Reach 3 Reach 4 Reach 5 Ecological Category (%) C C C C/D C (62 – 78) (62 – 78) (62 – 78) (58 – 62) (62 – 78) ↓ 66% ↓ 68% ↓ 65% ↓ 60% ↓ 64% Ecological Category TPC SASS5 score > 120 > 110 > 130 > 50 > 110 ↓ 125 ↓ 115 ↓ 35 ↓ 55 ↓ 115 SASS5 score TPC ASPT value > 5.4 > 6.0 > 5.0 > 5.0 > 5.0 ↓ 5.5 ↓ 6.1 ↓ 5.1 ↓ 5.1 ↓ 5.1 ASPT value TPC Key Indicator taxa 5 4 6 3 4 Key Indicator taxa TPC 3 3 2 2 2 missing missing missing missing missing
Conclusion • Very new ideas • Will be tested and adjusted through time and learning (Strategic Adaptive Management) Sponsorship: Kruger Marathon Club Thank you
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