Lorainne I. Rodríguez Vargas

Aquatic Biology Laboratory, Carlos Santos, PhD.

Biology Department, University of Puerto Rico, Mayagüez Campus

Vital to human life and social well being

Accelerating rates of degradation

In need of effective management

Engineered systems

Flood prevention

Crop irrigation

Navigation

Drinking water supply

Fishing

Industrial water supply

Generation of electrical power

Recreation

Wildlife refuge

EUTROPHICATION

Cultural eutrophication in lakes: The process by which humans stimulate algal productivity by elevating nutrient inputs (Smith 2003)

Continues to rank as one of the most common water quality problems in the world (Abrantes, 2006)

Two main approaches can be used for monitoring trophic status; direct chemical analyses or bioindicators.

The use of bioindicator species is considered to have advantages over intermittent chemical analyses, because organisms integrate environmental influences (Cox, 1991)

BIOLOGICAL INDICATORS

A species or population that, because of the ecological features of the species that constitute the community, provides an integrated record of the ecological environment ‐ an aquatic ecosystem for instance ‐ and thus provides early detection of biotic and abiotic modifications.

PHYTOPLANKTON

As the basis of the trophic chain, constitutes the biological community in which scientific attention is focused when a management plan is needed or an assessment of the ecosystem health is required (e.g. Monbet, 1992; Cloern, 1999; Sin et al., 1999).

Represent the basis of lake and reservoir food webs and respond fast to stresses and perturbations.

Unicellular algae

Distinguished by the presence of an inorganic cell wall composed of silica

Abundant in nearly every habitat where water is found – oceans, lakes, reservoirs, soils

Base of aquatic food webs in marine and freshwater habitats

There is a wide range in the number of species of diatoms present on earth, from 20,000 to over 1-2 million.

The high production of lipids in many diatom species has created great interest in diatoms as a source of biofuels.

It is estimated that 40% of the earth’s oxygen (02) is produced through the photosynthetic activities of diatoms.

Particular ranges of tolerance of pH (Battarbee, 1984), salinity and other environmental variables, including nutrient concentration, suspended sediment, flow regime, elevation, and different types of human disturbance.

Used extensively in environmental assessment and monitoring

Silica cell walls are ornamented and allows for identification with light microscope and SEM (Cox, 1996)

Bongo nets

Inverted light microscope

Sample digestion Scanning Electronic Microscope

Six reservoirs

Diatom identification

Diatom identification

Present in 25% or higher

Achnanthidium minutissimum

Centric diatoms

Navicula sp.

Ulnaria acus

Ulnaria ulna

Centric diatoms

Achnanthidium sp.

Navicula sp.

Ulnaria ulna

Ulnaria acus

Present in every reservoir

Achnanthidium minutissimum

Centric diatoms

Gomphonema sp.

Navicula sp.

Nitzchia sp.

Ulnaria acus

Ulnaria ulna

Centric diatoms

Achnanthidium sp. Navicula sp.

Ulnaria ulna Ulnaria acus Nitzschia sp.

Gomphonema sp.

A trophic scaling of indifferent

Has high tolerance of several environmental factors

Occurs under a wide range of ecological conditions

Found in oligo to hypereutrophic systems

Achnanthidium sp.

Regarded as the most common species of global diatom diversity and occupies a wide range of habitat types

Common in eutrophic lakes and rivers

Can grow in a wide variety of habitats but not in highly competitive situations

Centric diatoms

This species is eutrophication tolerant, has been associated with eutrophication in tropical streams

Indicator for eutrophic lakes

Ulnaria ulna

Pinnularia sp., Sellaphora pupula: Eutrophication tolerant

Gomphonema parvulum cosmopolitan, widely distributed in inland waters, and considered as indicators of eutrophic conditions

Gomphonema gracile is associated with eutrophication

Melorisa varians, pollution tolerant

Nitzchia palea, eutrophication tolerant

Reservoir monitoring including netplankton diatoms as an early indicator of trophic status

Abrantes, N., Pereira, R., Goncalves F. (2006). First step for an ecological risk assessment to evaluate the impact of diffuse pollution in lake vela (Portugal). Environmental Monitoring and Assessment 117: 411–431.

Batarbee, R. W., (1984). Diatom analysis and the acidification of lakes. Philosophical Transactions of the Royal Society of London Series B, 305: 451-477.

Cloern, J.E., (1996). Phytoplankton bloom dynamics in coastal ecosystems: a review with some general lessons from sustained investigation of San Francisco Bay, California. Reviews of Geophysics 34, 127e168.

Cox, E.J. (1991). What is the basis for using diatoms as monitors of river quality? In Use of Algae for Monitoring Rivers (Whitton, B.A., Rott, E. & Friedrich, G., editors), 33 – 40. Universita¨ t Innsbruck.

Cox, E.J. (1996). Identification of Freshwater diatoms from Live Material. Chapman & Hall. London.

Monbet, Y., 1992. Control of phytoplankton biomass in estuaries: a comparative analysis of microtidal and macrotidal estuaries. Estuaries 15, 563-571.

Sin, Y., Wetzel, R.L., Anderson, I.C., 1999. Spatial and temporal characteristics of nutrient and phytoplankton dynamics in the York River estuary, Virginia: Analysis of long-term data. Estuaries 22, 260-275.

Smith VH (2003) Eutrophication of freshwater and coastal marine ecosystems—a global problem. Environ Sci Pollut Res Int 10:126–139.

Lorainne I. Rodriguez Vargas

lorainneirv@gmail.com

Aquatic Biology Laboratory

Tropical Microbial Ecology Laboratory

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Trophic State Indexes

TSI TN (mg/L) TSI TP(mg/L) TSI Chl a (ug/L) TSI Secchi (m) CTSI

1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7

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