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Last updated: August 29, 2025
Species richness River Ravi — why floodplain diversity spikes and what it means for ecology & monitoring
Supporting LSI keywords: floodplain species richness, Balloki Headworks biodiversity, zooplankton richness, diversity indices River Ravi, seasonal richness peak, richness vs density, Shannon Simpson diversity, habitat connectivity
Introduction
How many microscopic species live in a single floodplain? The answer for the River Ravi’s Balloki floodplains is surprisingly high — and it changes with the seasons. Understanding species richness (how many species are present) is essential because it tells us about habitat connectivity, ecosystem resilience, and how floods shape biological communities. This post pulls verbatim excerpts from a detailed PhD thesis, explains the diversity metrics in plain language, and translates findings into monitoring and management advice for researchers and conservation practitioners.
Thesis snapshot — total richness and monthly peaks
“Zooplankton dynamics revealed a total of 157 zooplankton species belonging to 61 genera, 31 families, 14 orders and 8 classes. Highest number of species (82) was present in August while lowest (57) in January, with an overall mean of 70.5 species/month.” (p. 1).
This is a large species pool for a single floodplain system — 157 species total, with a clear seasonal signal: richness peaks in August (monsoon high water) and is lowest in January (winter low water).
What “species richness” and diversity indices mean (plain English)
Species richness (S) = the count of species found in a sample or area.
Species evenness (E) = how balanced abundances are across species (high evenness means no single species dominates).
Shannon & Simpson indices = combined measures that account for both richness and evenness to describe overall diversity.
The thesis reports both raw species counts and diversity indices (Shannon, Simpson, evenness), showing higher richness and evenness during flood months when connectivity increases and more habitats are available. (p. 127).
Why richness rises during floods — verbatim explanation and plain interpretation
“Species diversity showed positive, whereas species density showed negative relationship with the fluviometric level … The higher richness during maximum flood might be due to the fact that with flooding more habitats became available for colonization … High floods were responsible for exchange of propagules, nutrients, decomposed organic matter and organisms among neighboring habitats, increasing the suitability of habitate for colonisation.” (p. 127).
Plain English: when the river floods, it physically connects more pools, backwaters and channels, carrying eggs, cysts and tiny animals from different places into the floodplain. That adds species (richness), even though the number of individuals per litre often falls because the water spreads out (dilution).
Monthly patterns by group — exact thesis numbers and meaning
“The species diversity data revealed that a total of 157 species (protozoan’s 27, rotifers 101, copepods 27, and ostracods 2) were identified. Highest number of species (82) was recorded in August and lowest number of species (57) was recorded in January. The number of species increased from January to June. It was highest in August and then started decreasing.” (pp. 24–27).
Key takeaways:
- Rotifers account for most of the richness (101 species).
- Copepods & protozoans add important diversity (27 species each).
- Ostracods are present but species-poor (2 species).
This distribution explains why richness and ecological roles differ across months and groups.
Richness vs density — the important paradox for managers
“Zooplankton density showed that cumulative mean density ranged from 206.09 to 491.38 Ind. /L … One year mean density data revealed a main peak of 491.38 Ind. /L in June, with 70.39% and 25.10% contribution from rotifers and copepods respectively. … An inverse relationship between fluviometric level and zooplankton density was seen. It was observed that species diversity was highest in August, during high periods of flood. On the other hand zooplankton density was highest in June, when water level was lowest.” (pp. 1, 128).
Managers must track both metrics: richness tells you how many species the system supports (biodiversity/resilience); density indicates productivity (food availability for fish). Flood months → richness ↑ and density ↓ (dilution). Early summer → density ↑ (productive but fewer species dominating).
Spatial patterns that shape local richness (horizontal & vertical)
“Spatial variations (horizontal) of zooplanktons were early littoral (493.70 Ind./L), late littoral (330.71 Ind./L) and limnetic (257.36 Ind./L), while spatial variations (vertical) of zooplanktons were surface (257.36 Ind./L), middle (251.86 Ind./L) and bottom (270.44 Ind./L).” (p. 1).
Although those figures describe densities, the thesis also maps richness across zones: littoral (shoreline) areas support both higher densities and often higher local species richness because of vegetation, microhabitats and nutrient influx. Vertical heterogeneity (surface–bottom) provides refuges and niche space that increases total richness at the floodplain scale. (pp. 24–28).
Mechanisms behind richness increases — biological & physical drivers
- Connectivity: floodwaters connect isolated pools, allowing colonization. (p. 127).
- Habitat heterogeneity: varied microhabitats (vegetated margins, backwaters) offer niche space for different species (pp. 24–28).
- Propagule exchange: floods move cysts/eggs and juvenile stages between habitats, elevating local species pools (p. 127).
- Dilution & reduced competition: dilution can reduce competitive exclusion, temporarily increasing evenness and allowing rarer species to appear (p. 127).
How to measure and report richness properly (practical checklist)
- Monthly sampling across seasons — richness changes markedly Jan → Aug; capture both low and high fluviometric periods. (pp. 24–28, 127).
- Spatially stratified sampling — include early/late littoral and limnetic stations plus multiple depths to capture microhabitats. (pp. 1, 28).
- Use multiple diversity metrics — report raw S (species count), Shannon, Simpson and evenness to show different aspects of diversity (p. 127).
- Pair with physicochemical data — fluviometric levels, temperature, turbidity, conductivity explain much of the richness pattern. (pp. 92–95, 127).
- Archive voucher specimens and images — for future taxonomic verification (thesis plates 12–18 show photographic vouchers). (pp. 119–126).
For standard methods and indices, see the Pielou (1966) diversity framework and modern primers on biodiversity metrics (thesis bibliography references Pielou).
Monitoring & conservation implications
- Floodplain reconnection tends to increase regional biodiversity — valuable for conservation planning. (p. 127).
- Fisheries management should note that high density (June) supports larval growth, while high richness (August) signals resilient habitat complexity. (pp. 1, 128).
- Climate change & water withdrawal: shifts in flood timing/extent will alter richness patterns — baseline data from this thesis help detect long-term change (pp. 3–4).
Short FAQs (evidence-backed)
Q: When is species richness highest on the River Ravi?
A: August — the thesis recorded 82 species that month (highest), with an annual total of 157 species. (p. 1; pp. 24–27).
Q: Does flood always increase richness?
A: In this system, yes — richness increased with fluviometric level due to connectivity and propagule exchange, though other studies vary by context (p. 127).
Q: Should managers track richness or density?
A: Both. Richness measures biodiversity/resilience; density measures productivity and food availability. The thesis shows they behave inversely during floods (pp. 1, 127–128).
Conclusion
The Balloki Headworks thesis documents a high and seasonally dynamic species pool: 157 zooplankton species total, richness peaking in August, and a clear richness vs density trade-off driven by flood pulses and water chemistry. For researchers, conservationists and water managers, the key message is simple: measure both richness and density, sample across space and time, and pair biological data with hydrology to get the full ecological picture of the River Ravi floodplains.
Disclaimer: Some sentences have been lightly edited for SEO and readability. For the full, original research, please refer to the complete thesis PDF linked in the section above.
Author bio
Altaf Hussain, PhD candidate, Department of Zoology, Government College University Lahore. Supervised by Dr. Abdul Qayyum Khan Sulehria, Associate Professor, Department of Zoology, GCU Lahore. Thesis submitted in 2015.
Source & Citations
Source & Citations
Thesis Title: Zooplankton Assemblage in Flood Plains of River Ravi near Balloki Headworks
Researcher: Altaf Hussain
Guide (Supervisor): Dr. Abdul Qayyum Khan Sulehria
University: Government College University (GCU), Lahore
Year of Compilation: 2015
Excerpt Page Numbers used: p. 1 (abstract & summary), pp. 24–29 (diversity & richness tables), pp. 119–126 (plate vouchers), p. 127 (discussion on fluviometric effects), pp. 92–95 (correlation summary).
Other trusted external links used in body: UNESCO floodplain/hydrology resources (https://en.unesco.org), FAO plankton/fisheries guidance (https://www.fao.org), Encyclopedia of Life (https://eol.org). These add context and trust without pointing to direct competitors.
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