Sights unseen, the magical miniature world of aquatic invertebrates
By Jeanne Gouws, Freshwater Ecologist
When it comes to the animal Kingdom, conservation is not all about everything big. Big and “furry”, big and “leather-y” or big and “scale-y” vertebrates are not the be-all and end-all of biodiversity. The smaller invertebrate beings, often alien looking, are frequently forgotten. CapeNature ecologists, however, did not forget about the aquatic invertebrates during recent river surveys, just before lockdown. Numerous river sites were visited during December 2019 and February and March 2020.
Teloganodidae, Barbarocthonidae, Sericostomatidae, Glossosomatidae. These big word tongue-twisters are the family names of some of the endemic mayflies and caddisflies that call the South Western Cape rivers home. It is not surprising then that they were collected in the healthy upper parts of rivers of the Hexrivier, Riviersonderend and Grootvadersbosch catchments in the Western Cape.
These insects, like several others, prefer good quality water and share their slightly acidic, often peat stained watery homes with numerous other invertebrates. Some of the invertebrates collected during the surveys, could be seen with the naked eye and for others, a magnifying glass was needed. Some are fully aquatic, like riffle and marsh beetles and most bugs, spending their entire lifecycle in the water. Most are semi-aquatic, like dragonflies and damselflies, spending their early life stages under water and their adult stages above.
These and other invertebrates, including flies, bugs, crabs and snails (amongst others), have differing tolerances to pollution levels in water. The super sensitive stoneflies and the endemic caddisflies are found in mountain streams and upper foothill rivers with good water quality.
Common midges, mosquitos and freshwater earthworms can tolerate polluted waters, and were found at both healthy and polluted river sites during the recent surveys.
By assessing the health of ecosystems and providing distribution records for taxa our ecologists play a crucial role in contributing to the documenting of the unique biodiversity of our province. This in turn then ensures that the ecosystems housing these taxa are managed in an informed way, taking all relevant fauna and flora into account.
Related News
Wildfires intensify as climate shifts, CapeNature warns in emergency podcast series
CapeNature has released a special series of its acclaimed Green Noise podcast, offering an urgent and deeply human perspective on South Africa’s recent wildfire season. The series has a particular focus on the devastating fires in the Cederberg Wilderness and changing weather patterns. The fire in the Cederberg Wilderness, which ignited on 22 December 2025 along Uitkyk Pass
Western Cape to benefit from CapeNature’s 2026 Greening Initiative
CapeNature is launching a fun and engaging greening competition for schools and communities across the Western Cape. The competition will start on 13 April 2026 to coincide with International Plant Appreciation Day and will run until 15 May 2026. The initiative aims to inspire learners and community members to actively participate in protecting the environment.
A follow up: The potential impacts of Red Swamp crayfish in Western Cape waters
Since first being found in the canal systems of lower Olifants River in 2022 by CapeNature officials, invasive Red Swamp Crayfish (Procambarus clarkii) are being found further afield in the Western Cape at an alarming rate. This freshwater species is globally recognised as a seriously damaging invasive species.
Over 43 000 Cape Gannets on Lambert’s Bay Bird Island this breeding season
Bird Island is alive with the sounds and spectacle of seabirds, with an estimated over 43 000 Cape Gannets currently making the island their home this breeding season. The thriving colony reinforces Bird Island, Lambert’s Bay, as one of South Africa’s most important gannet breeding sites and highlights the impact of ongoing marine conservation work.
Water Week: Protecting Our Most Precious Resource
Water is fundamental to life and essential to our daily wellbeing. While this may seem widely understood, it remains important to continually remind ourselves of the value of this finite resource. Although approximately 70% of the Earth’s surface is covered by water, only about 2.5% of it is freshwater available to sustain ecosystems and human needs.
New SASS accreditor supports river biomonitoring in the Western Cape
CapeNature continues to strengthen its role in freshwater conservation through the expertise of its staff, with freshwater ecologist Jeanne Gouws receiving her South African Scoring System (SASS) accreditation as an accreditor. Having successfully passed every three-yearly assessment since 2007, she is now the official Western Cape SASS accreditor.