shaik umme sama.AEM , MFK -1710 COLLEGE OF FISHERIES MANGLORE

1. MANAGEMENT OF WETLANDS THROUGH
BIOMANIPULATION – TOP DOWN AND
BOTTOM UP METHODS
SK.UMME SALMA,
MFK 1710,
AEM.

2. INTRODUCTION
•Wetlands-ecological engineers for waste water treatment.
•Importance –filter,sinks,transformation sites to chemicals.
•Threats.
•Management-to protect, restore, manipulate or to provide for
their functions and values

3. • Shapiro et al., (1975), The alteration of an ecosystem by adding
or removing species, especially predators
• Manipulation of all lake biota and their habitats
• Adjusting the biological community to achieve a desired
outcome
BIOMANIPULATION

5. • An option for restoring turbid lakes and reservoirs
characterized by high algal blooms
• Widely accepted
• Frequently applied eco-technology to improve the
environmental quality of standing waters
• It is a tool to control
• Algal blooms
• Restore the lake to a clear water state as well as improving the
water quality

6. • Conserving the biodiversity
• Enhancing fisheries and promoting the socio-economic
functions of the reservoir
• To address the problems and challenges that are posed by
eutrophication in lentic water bodies
• Efficiently work with-
• Lake area <4 ha most suitable (Reynolds 1994)
• Water depth < 3 m more effective in shallow

7. •Reduce grazing pressure on zooplankton
•Increasing grazing pressure on phytoplankton
•Less turbid water
•Removal of pest species
•Reduced phytoplankton blooms
DESIRED BENEFITS

8. EUTROPHICATION
• Natural, slow process - High concentration of nutrients-
phosphorous and nitrogen
• Many aquatic ecosystems affected by agricultural or urban
activities remain eutrophic
• Leads to– excess growth of algae, poor water quality, low
transparency, anoxia, loss of biodiversity, disruption of food-
web interactions, socio-economic functions of water bodies
etc.

9. BIOMANIPULATION IS IMPORTANT
• Negatively effect the functions of water bodies ( reservoirs) in
providing domestic, industrial water supply, fish production,
irrigation, recreation etc.
• Increase in algal biomass ,including toxic cyanobacteria
• Cyanobacteria blooms can cause serious health problems
including liver damage, promotion of tumor growth,
gastroenteritis, hepatitis etc.

10. BIOMANIPULATION TECHNIQUES
• Increasing or decreasing the numbers of consumers to control
the lower level organisms is called Biomanipulation

11. Bottomup
Topdown

13. BOTTOM UP
• Each group, such as the algae, zooplankton or Piscivore, has a
functional role in the ecosystem
• An attempt to reduce nutrients to control algae, is a type of
bottom-up method
• The method that most consistently works for controlling
algae(algaecides & herbicides)

14. • However nutrient reduction can be difficult/expensive to
control, especially in agricultural areas and causes risk to
humans, live stock, and other aquatic organisms

15. Top down
• It is an attempt to control the lower level organisms by
altering the organisms at higher level (predators)
• Effects of predation
• By increasing the no. of zooplankters we can reduce the
abundance of phytoplankton

16. Biomanipulation tools
• Top-down grazing effect of zooplankton
• Fish assemblages
• Removal of zooplanktivorous, benthivorous fishes
• Stocking of piscivorous fish species
• Ensuring moderate macrophytes abundance

17. Fish Zooplankton grazing
assemblages
• The bottom-up effect created by high nitrate & phosphate
loading in lentic water bodies resulting in dense algal blooms
could be effectively checked by top-down grazing effect of
zooplankton
• Effective zooplankton grazing on phytoplankton is a powerful
means of controlling the high population density of algae in
eutrophic water bodies ( ex. Daphnia, bosmina)

18. Fish assemblages
• Zooplanktivorous fishes (Barbus) will check the biomass of
zooplankton, there by allowing the phytoplankton to flourish,
but these fishes are themselves controlled by piscivorous
fishes like Clarias species which feed on their fries

19. Benthivorous fish reduction
• A reduction in benthivorous fish -a favorable impact on the
biomanipulation process(Lamarra 1975)
• They stir up the bottom when feeding
• Impairing the colonization & growth of macrophytes
• Enhancing turbidity
• eg:GIZZARD SHAD

20. • Aquatic macrophytes play a very important structuring role in
most fresh water ecosystems
• Have been identified as a key component for the long term
success of biomanipulation management
• Submerged macrophytes provide refugee for zooplankton
(Daphnis)
• Thus contributing to more control of phytoplankton via
zooplankton grazing
• They also control phytoplankton via competition for light and
nutrients

21. • The biomass of the planktivorous fish is often positively
related to nutrient levels and ecosystem productivity
• Planktivorous fishes (e.g. shad, sardine) dominates in nutrient
rich lakes

22. • Piscivorous fishes (e.g. bass, pike) tend to dominate the fish
community of nutrient poor, oligotrophic lakes
• Hence Biomanipulation is readily acceptable wetland
management practice
• Much effective when both methods are applied
• It is-Low cost, Absence of machinery, High effectiveness,
Absence of toxic chemicals

24. In shallow coastal waters, perennial seagrass and seaweed beds provide
food and shelter for numerous invertebrates and fishes, and the
habitats they form are global hotspots for marine diversity and
production
INTRODUCTION
(Walker & Kendrick 1998; Williams &
Heck 2001; Waycott et al. 2009;
Barbier,Leslie & Micheli 2013).

25. These habitats are exposed to several anthropogenic pressures, such as
increasing populations within these habitats may be overexploited
As a result, seagrass beds have declined globally by up to 7% per year
since 1990 (Waycott et al. 2009) and perennial macroalga (e.g. Fucus
spp.) habitats have decreased in many coastal areas (Kautsky et al.
1986;Vogt & Schramm 1991; Munda 1993).
(Waycott et al. 2009; Worm & Lenihan
2013; Seitz et al. 2014).
HHH

26. MATERIALS AND
METHODS

27. • We identified the available scientific literature on top-down
and/or bottom-up experiments in coastal seagrass Zostera
marina and seaweed Fucus spp. habitats using the ISI Web of
Science Core Collection data base (1945–2014).
• studies conducted in the northern part of the Atlantic Ocean,
including the Baltic Sea and that contained either Fucus spp.
or Zostera marina and ephemeralmacro- and microepiphytic
algae were used.
• In total, we included data from 48 independent studies (but
each study included several different experiments for which
we recorded the following eight variables

28. (i) type of experiment (mesocosm, enclosure, exclosure,
ambient)
(ii) substrate type (soft, hard, mixed)
(iii)volume
(iv) area of experimental unit (ranging~1 L to >600 m3)
(v) average water temperature (7–27 °C)
(vi) salinity (5–32 psu)
(vii) duration of experiment (4–250 days)
(viii)season (spring, summer, autumn or whole season).

29. • reveal how bottom-up and top-down effects penetrate the
foods, we divided trophic levels into different groups.
• Ephemeral algae were divided into macroalgae (epiphytic or
matforming filamentous or sheath-like algae) microephiphytes
(unicellular algae, for example diatoms), because they are to a
large extent eaten by different grazers and represent different
energy paths in the food web

30. • Ephemeral macroalgae were further divided into green and red/brown
algae because of their different light requirement,growth and palatability
• Grazers were divided into crustaceans (amphipods and isopods)
• gastropods, as the two groups have different capacities to graze different
algal species and respond to blooms of ephemeral algae, and may also
show differences in vulnerability to predation.

31. RESULTS AND
DISCUSSION

32. • EPHEMERAL MACROALGAE
• Across all studies, the magnitudes of top-down and bottom-
up controls on ephemeral macroalgae were similar
• MICROEPIPHYTES
• Across studies, microepiphytes were more strongly affected
by top-down effects from grazers effects from nutrients
• There were similar negative top-down effects of gastropods
and amphipods/ isopods on microepiphytes.

33. • ZOSTERA/FUCUS
• Perennial macrophytes as a group responded more strongly to
bottom-up effects of nutrients than top-down effects of
consumers.
• CONSUMERS
• Across all studies and grazer groups, grazer abundance was
more strongly affected by top-down than bottom-up control.
• Nutrient addition had no significant bottom-upeffect on total
grazer abundance or abundance of gastropods alone but had
a positive effect on amphipod/isopod abundance

34. CONCLUS
ION

35. • Eutrophication favours fast-growing ephemeral algae over
perennial macroalgae and seagrasses, causing habitat
degradation.
• Here, we review the literature on experiments that test top-
down and bottom-up controls in seagrass Zostera marina and
seaweed Fucus spp. food webs in the North Atlantic.
• Presence of mesopredators on average doubled the biomass
of ephemeral algae through trophic cascades, mainly
mediated via negative effects on amphipods and isopods.

36. • top-down effects on ephemeral algae at all trophic levels are
on par with eutrophication effects.
• However, the few studies manipulating piscivorous fish make
estimates of their top-down effects uncertain.

37. THANK
YOU