Development of beneficial freshwater algae

Development of beneficial freshwater algae

DREVO Living Waters Algae & Periphyton System

Concept

In the systemDREVO Living MountainsFreshwater algae are considered one of the basic levels of life in rivers, streams, swamps, floodplain lakes and restored water bodies.

They are capable of:

convert solar energy into organic matter;

form the basis of the aquatic food web;

serve as food for zooplankton, mollusks, insect larvae and fish;

release oxygen during daylight hours;

bind some of the dissolved nutrients;

create biofilms on rocks, wood and plants;

maintain self-purification of water;

participate in the formation of bottom sediments;

serve as indicators of water quality.

However, algae only remain beneficial at a balanced density. Excessive growth of phytoplankton and cyanobacteria can cause toxic blooms, reduced transparency, and oxygen deficiency. Some freshwater cyanobacteria produce microcystins, anatoxins, cylindrospermopsin, and other hazardous substances.

The main principle:

The project's goal is not to fertilize the water to promote rapid algae growth, but to create conditions for a sustainable diversity of local aquatic producers.

1. What is considered beneficial algae?

Usefulness is determined not only by the name of the species, but also by its function, abundance and place of development.

Benthic microalgae

Live:

on the stones;

on gravel;

on wood;

on bottom sediments;

on the stems of aquatic plants.

They are part ofperiphyton— a complex biofilm of algae, bacteria, fungi, protozoa and organic material.

Periphyton:

is food for aquatic invertebrates;

binds dissolved substances;

saturates the microzone with oxygen;

participates in self-cleaning;

quickly responds to changes in water quality.

At the same time, periphyton is capable of accumulating pollutants and transmitting them along the food chain, so it cannot be artificially developed in polluted water without analyzing the bottom sediments.

Diatoms

Diatoms are especially important in:

clean streams;

rivers;

spring reservoirs;

shallow waters with rocky and gravelly bottoms;

cold and temperate waters.

They form thin films on the substrate and serve as food for:

snails;

mayfly larvae;

caddis flies;

crustaceans;

young fish.

Their diversity is often used to assess the ecological state of watercourses.

Green microalgae

In moderate concentrations they support:

zooplankton;

fry;

filter feeding animals;

natural productivity of ponds and floodplain water bodies.

But dense green phytoplankton is not automatically beneficial: excessive biomass can also lead to nocturnal and postmortem oxygen deficiency.

Charophytes

Charophytes are large benthic algae that resemble higher aquatic plants.

They can:

form underwater meadows;

stabilize precipitation;

create shelters for invertebrates and young fish;

maintain clear water;

compete with excess phytoplankton for nutrients.

Their restoration is particularly promising in:

clean lakes;

transparent backwaters;

shallow calcareous reservoirs;

protected floodplain bowls.

Only local species and material from the same catchment area are used.

Local filamentous green algae

In small quantities they:

create shelters;

provide substrate for invertebrates;

participate in primary production.

With mass development they:

cover the bottom with thick mats;

retain garbage;

interfere with the flow;

cause strong daily fluctuations in oxygen;

deteriorate spawning grounds.

Therefore, filamentous forms are not a target crop, but a controlled part of the community.

2. Cyanobacteria: a necessary group, but not a target for cultivation

Cyanobacteria are often called blue-green algae, although biologically they are photosynthetic bacteria.

In the natural ecosystem they participate:

in primary production;

in the nitrogen cycle;

in the formation of biofilms;

in the nutrition of individual organisms.

But it is impossible to artificially stimulate their mass development.

Genera and groups that can form dense or toxic blooms are dangerous, including:

Microcystis;

Dolichospermum;

Aphanizomenon;

Planktothrix;

Raphidiopsis;

individual benthic cyanobacteria.

It is impossible to reliably determine the toxicity of a bloom by its appearance, so suspicious clusters require water and biomass analysis.

3. Environmental goal

The project should aim not for the maximum mass of algae, but for the following state:

high species and functional diversity;

thin, stable periphyton;

clear or moderately clear water;

absence of a dense surface film;

stable oxygen regime;

presence of underwater plants;

temperate phytoplankton;

developed zooplankton;

presence of mollusks and aquatic insects;

absence of dominance of toxic cyanobacteria.

4. Main development areas

Springs and upper streams

Priority is given to:

diatom communities;

thin periphyton;

aquatic mosses;

biofilms on stone and wood.

Necessary:

keep water cool;

maintain shading;

do not apply fertilizers;

do not silt up the gravel;

protect the source from livestock.

Mountain and medium-sized streams

Different substrates are created:

boulders;

pebble;

gravel;

wood;

quiet side pockets;

areas of moderate flow.

This forms different communities of algae and invertebrates.

Floodplain lakes and oxbow lakes

Priority:

temperate phytoplankton;

Characeae algae;

underwater plants;

periphyton on vegetation;

developed zooplankton.

Connection to the floodplain is necessary, but without a constant supply of fertilizers and manure.

Swamps

In swamps, algae develop:

in shallow windows;

on sphagnum;

on the sedges;

in seasonal bowls;

on wood;

in small channels.

A natural swamp should not be converted into a highly productive algae pond.

Artificial biofiltration reservoirs

Here, controlled development of algal biofilms is possible for:

nutrient capture;

preliminary wastewater treatment;

production of technical biomass;

zooplankton nutrition.

Such basins must be separated from the natural core and have the ability to collect biomass.

5. Creating a suitable substrate

To develop beneficial periphyton, surfaces of different structures are created.

Stone substrate

Used:

local boulders;

pebble;

coarse gravel;

flat stones.

Stones create:

illuminated surfaces;

shadow sides;

zones of different flow speeds;

shelters for invertebrates.

Wood substrate

Applicable:

immersed branches;

root systems;

firmly fixed trunks;

wooden grates.

Wood supports:

seaweed;

mushrooms;

bacteria;

insect larvae;

mollusks.

Pure, untreated wood from local species is used.

Plant substrate

Submerged and riparian plants provide a large area for periphyton.

Particularly valuable are:

submerged leaves;

stems of sedges and rushes;

root systems;

underwater meadows.

Porous mineral modules

The following can be used in technical biofilters:

porous ceramics;

natural pumice;

lava stone;

zeolite carriers;

mineral mesh cassettes.

In a natural reservoir, artificial modules are used sparingly, so as not to replace the natural substrate with a technical structure.

6. Light mode

Different algae require different lighting.

To create diversity, a mosaic is needed:

sunny shallow waters;

partial shade;

shaded banks;

open water windows;

areas under wood;

deeper zones.

Complete removal of shoreline trees leads to overheating and may increase unwanted algae growth.

Complete shading, on the contrary, suppresses primary production.

Therefore, the alternation of open and shaded areas is maintained.

7. Nutrient management

The main source of harmful blooms is not a lack of "beneficial algae," but an excess of available nutrients, primarily nitrogen and phosphorus.

Sources:

agricultural runoff;

mineral fertilizers;

manure;

domestic wastewater;

fish farming;

erosion of fertile soil;

contaminated bottom sediments;

storm sewer.

The EPA indicates that the most effective prevention of blooms is to reduce nitrogen and phosphorus inputs from point and non-point sources.

DREVO measures

buffer strips;

wet meadows;

filtration swamps;

sediment traps;

separate collection of manure;

closed drinking bowls;

floodplain restoration;

reduction of slope erosion;

domestic wastewater treatment;

limitation of phosphate discharges;

aquaculture control;

removal of excess biomass from technical pools.

8. Why can't you just fertilize a natural reservoir?

In fish ponds, fertilizer is sometimes used to increase phytoplankton levels as a natural food source. The FAO describes this approach for managed production ponds.

But this method cannot be automatically transferred to:

natural lakes;

rivers;

swamps;

springs;

drinking water bodies;

protected floodplains.

The result may be:

cyanobacterial bloom;

night drop in oxygen;

fish death;

accumulation of toxins;

disappearance of underwater plants;

replacement of a diverse community with a few dominant species.

9. Oxygen regime

Algae release oxygen in the presence of light, but at the same time they respire.

At night, photosynthesis stops, but oxygen consumption continues.

After the mass death of algae, bacteria decompose the biomass and consume additional oxygen. Therefore, high daytime oxygen levels do not necessarily indicate prosperity.

Controlled by:

oxygen before dawn;

oxygen during the day;

daily amplitude;

temperature;

depth;

flow speed;

organic load.

The most dangerous moment often occurs before dawn and after the bloom has dissipated.

10. Support for zooplankton

Beneficial phytoplankton should be included in the food web.

Required:

rotifers;

cladocerans;

copepods;

other local filter feeders.

They:

consume microalgae;

maintain transparency;

serve as food for fry;

redistribute nutrients.

To save them you need to:

do not stock all the bowls with fish;

maintain areas free from fishing pressure;

exclude insecticides;

maintain underwater vegetation;

avoid toxic blooms.

11. Mollusks and other filter feeders

Local bivalves are able to filter water and bind phytoplankton particles.

But they cannot be released as universal “living filters”.

Required:

suitable water;

correct bottom;

natural fish hosts for the larvae of a number of species;

absence of toxic contaminants;

genetic suitability for the catchment area;

protection against invasive mollusks.

Priority is given to restoring local populations rather than introducing alien filter feeders.

12. Underwater plants as partners of algae

A healthy pond should not be managed solely by phytoplankton.

Underwater plants:

compete for nutrients;

stabilize bottom sediments;

create a substrate for periphyton;

provide shelter for zooplankton;

support fish and invertebrates;

reduce re-suspension of sludge.

The goal is to create a combination of:

phytoplankton;

periphyton;

Charophyta algae;

underwater higher plants;

floating plants;

coastal vegetation.

13. DREVO Algae Nursery

A research nursery could be established for rare and useful local communities.

It includes:

a collection of samples from different catchments;

microscopic laboratory;

cultivation system;

genetic identification;

quarantine;

small experimental pools;

control of light, temperature and nutrients;

digital passport bank.

Purpose:

study of local species;

restoration of sterile artificial substrates;

creation of starting biofilms;

support for scientific projects;

production of biomass for technical filters.

Material from the nursery must not be released into natural waters without checking its origin, pathogens, and environmental risks.

14. Transfer of natural periphyton

It is safer to transfer not a concentrated algal culture, but a small amount of mature local periphyton.

Possible sequence:

a healthy donor site is selected in the same catchment area;

the absence of pollution and invasive species is confirmed;

the minimum number of stones or wooden slabs is selected;

part of the biofilm is transferred to the prepared substrate;

the donor site is not damaged;

development is monitored microscopically and chemically;

If there is undesirable dominance, the experiment is terminated.

In many cases, natural introduction is preferable to artificial introduction.

15. Technical algal biofilters

For the treatment of agricultural or domestic wastewater, separate shallow pools with controlled algal biomass can be used.

Functions:

nitrogen and phosphorus fixation;

oxygen formation;

support bacterial purification;

biomass production;

reducing the load on the natural swamp.

The FAO notes that in managed algal ponds, algal biomass can bind nutrients and support oxygen for bacteria and other aquatic life.

Mandatory condition

Nutrients are removed from the system only when a portion of the algal biomass is regularly harvested.

If the biomass dies in the same pool, a significant portion of the substances returns to the water.

16. Use of collected biomass

After laboratory analysis, clean biomass from technical pools can be considered as raw material for:

biogas;

composting;

biochar;

fertilizers;

obtaining pigments;

technical biomaterials;

feed research;

wastewater treatment.

Biomass from contaminated water is not automatically used in agriculture, as it can accumulate:

heavy metals;

organic pollutants;

pathogens;

cyanotoxins.

17. Monitoring

Basic parameters

Controlled by:

temperature;

transparency;

turbidity;

pH;

electrical conductivity;

dissolved oxygen;

nitrogen;

phosphorus;

chlorophyll-a;

depth;

flow speed;

organic carbon.

Biological control

The following are determined:

phytoplankton composition;

periphyton composition;

proportion of diatoms;

proportion of cyanobacteria;

presence of toxigenic groups;

state of char communities;

zooplankton;

aquatic invertebrates;

mollusks;

fish;

underwater vegetation.

Toxins

If flowering is suspected, the following are checked:

microcystins;

toxoids;

cylindrospermopsin;

saxitoxins;

other regionally significant compounds.

WHO recommends assessing the risk of cyanobacteria across the entire water system, including detection, prevention and management of exposure to toxins.

18. Living Mountain Observatory

The system combines:

stationary probes;

automatic samplers;

underwater cameras;

spectral sensors;

microscopic stations;

TREVO AeroSense Drone;

River Rover Scout;

satellite images;

meteorological data;

Mountain Digital Twin.

Remote sensing methods help detect changes in bloom color and area, but do not replace laboratory identification of species and toxins.

19. DREVO AI Algae Watch

Artificial intelligence analyzes:

chlorophyll growth;

change transparency;

temperature;

nutrient concentration;

oxygen before dawn;

weather conditions;

stagnation of water;

spectral features;

microscopy results;

history of previous flowerings.

The system predicts:

risk of cyanobacterial bloom;

probable oxygen deficiency;

the need for sampling;

nutrient supply areas;

optimal time for removal of technical biomass;

the need to temporarily close the reservoir.

Warming waters combined with nutrient pollution can increase the frequency and severity of harmful blooms, so climate data should be included in the risk model.

20. Prevention of harmful flowering

Prevention is the priority.

On the watershed

reduction of fertilizers;

precise application of nutrients;

protection of soil from erosion;

forest and grass buffers;

restoration of swamps;

wastewater treatment;

control of livestock sites;

preventing direct runoff of manure.

In the reservoir itself

restoration of flow;

elimination of stagnant overheated pockets;

support for underwater plants;

removal of excess technical biomass;

limiting bottom disturbance;

fish management;

conservation of zooplankton;

preventing continuous feeding of waterfowl.

21. Actions during flowering

If the water becomes:

bright green;

bluish-green;

brown;

paint-like;

becomes covered with flakes or film;

acquires a musty smell,

necessary:

stop bathing and watering animals;

restrict access by people and pets;

take samples;

identify organisms and toxins;

measure oxygen;

find a source of nutrients;

temporarily stop the household discharge;

prepare aeration in case of risk of fish death;

do not destroy blooms mechanically without assessing the spread of toxins;

inform water and sanitary control authorities.

Chemical algaecides should not be the first response: cell destruction can release toxins, and mass dieback can degrade oxygen levels. The EPA views physical and chemical methods as measures to control existing blooms, which have limitations and side effects.

22. What not to do

The following is not allowed:

fertilize a natural swamp for algae;

add manure directly into the pond;

purchase unknown microalgae cultures;

release species from another catchment;

grow spirulina or chlorella directly in the natural floodplain;

consider any green water a sign of productivity;

rely only on the appearance of water;

using toxic blooms as fertilizer without analysis;

destroy all aquatic vegetation;

populate all bowls with fish;

use copper preparations without environmental assessment;

return the collected biomass to the same reservoir;

allow livestock access to shallow biofiltration zones;

locate algae production in a natural core.

23. DREVO pilot model

For the first pilot, it is not a natural lake that is recommended, but a separate controlled system.

Pilot composition

inlet sediment trap;

first sedimentation basin;

shallow algal biofilter;

cassettes with stone and wood;

underwater plants sector;

zooplankton area;

outlet plant filter;

automatic sensors;

the possibility of completely blocking the exit;

biomass collection system.

Aim the pilot

reduce nitrogen and phosphorus;

to form a stable periphyton;

prevent cyanobacteria from dominating;

obtain safe technical biomass;

identify local species;

develop an operating mode for different seasons.

24. Success criteria

The system works correctly if:

the water does not show toxic blooms;

moderate transparency is maintained;

oxygen does not drop to dangerous levels before dawn;

different groups of algae are present;

zooplankton and aquatic invertebrates are developed;

underwater plants are preserved;

there is no mass death of fish;

the intake of nitrogen and phosphorus decreases;

technical biomass is removed regularly;

Natural reservoirs do not depend on the constant artificial introduction of crops.

Mission

Freshwater algae are not pollutants in themselves. They are the first living link that converts light and dissolved substances into food for the aquatic ecosystem.

But there is a fundamental difference between a healthy biofilm and a destructive bloom.

Task DREVO Living Waters Algae & Periphyton Systemis to:

develop local diatoms and periphyton;

restore char and underwater meadows;

maintain moderate phytoplankton;

associate algae with zooplankton, mollusks, insects and fish;

reduce the intake of excess nutrients;

use technical algae pools before the runoff enters the natural system;

detect dangerous blooms before an environmental disaster occurs.

It is not the greenest water that is beneficial, but water in which algae take their place in a complete and sustainable food web.