Eutrophication 3 Consequences of Eutrophication Alice Newton

Consequences of Eutrophication

Main Impacts of Eutrophication, EEA   Ecological  reductions in biodiversity;  Changes in the structure and functioning of the marine ecosystems;  Socio-Economic  · reductions in the natural resources of dermersal fish and shellfish;  · reduced income from maricultures of fish and shellfish;  · reduced recreational value and income from tourism;  · increased risk of poisoning of animals including humans by algal toxins.

Consequences of Eutrophication heed.unh.edu/report.html heed.unh.edu/report.html  Ecological  Hypoxia and Anoxia  Increased sulphides and H 2 S  Increased phyto biomass & HAB  Increased turbidity  Decreased biodiversity  Loss of seagrass and kelp beds  Coral reef destruction  Marine mammal & seabird deaths  Socio-Economic  Decreased fisheries and aquaculture yields  Fish kills  Shellfish poisoning  Contamination of aquifers, taste, odour, NO 3 & NO 2  Loss of tourism revenues

Direct and Indirect Responses DirectChlorophyll Primary Production Macroalgal biomass Sedimentation of OC Si:NN:PHAB Phytoplankton community Indirect Benthic community Pelagic community Vascular plants Habitat diversity Transparency OC in sediments Sediment biogeochemistry Bottom water Oxygen Seasonal cycles MortalitiesBiodiversity Cloern, J.E Review. Our evolving conceptual model of the coastal eutrophication problem. Mar. Ecol. Prog. Ser. 210: )

Hypoxia & Anoxia  Night-time oxygen sag due to excessive respiration of algal bloom  Bloom “die off” and decomposition raises BOD  Hypoxia (<2ppm) or anoxia may result  Less mobile animals most affected  Changes in community structure to short lived spp eg polycheate worms  Changing interactions of predator-prey eg vertical migration of zooplankton perturbed

Hypoxia & Anoxia 1/html/kap04_eng.htm Dead fish float!

How does the bottom layer become hypoxic? (Time magazine)

Sulphides and H 2 S  Plant material (decomposing blooms) settles to seabed  Decomposition results in elevated concentrations of sulphides  Affects benthos eg seagrasses  Anaerobes

Phytoplankton community  Nutrients boost phytoplankton production leading to blooms  Water becomes turbid and oxygen depleted  Eutrophication alters Si:N  Diatoms require Si but flagellates do not eg off German coast N&P have increased 4x relative to Si, diatoms have decreased and flagellates have increased 10x.  Shift in phytoplankton community may favor toxic algae leading to HAB

“Red” Tides...HAB Noctiluca in California Not Always Red…

HABwww.fmri.usf.edu/ecohab/gallery.HTM  Natural phenomenon, increased frequency linked to eutrophication.  “Red” tides, may in fact be brown or green. Some are toxic in low concentrations and do not discolor the water  Non-toxic blooms can be lethal because of anoxia or hypoxia  Toxic tides may be toxic to vertebrates such as fish and cause fish kills  Toxic tides may NOT be toxic to shellfish that accumulate them causing shellfish poisoning of humans

Some HAB Species Dinophysis & Ceratium Alexandrium Pfisteria Pseudo-nizschia

Alexandrium monilatumAlexandrium monilatum Water discoloration in Tampa bay, summer Alexandrium monilatum Chattonella subsalsaChattonella subsalsa Chloromonad. Produces brevetoxins Chattonella subsalsa CryptoperidiniopsoidCryptoperidiniopsoid Dinoflagellates linked to fish kills. Cryptoperidiniopsoid Dinophysis groupDinophysis group e.g. D. caudata, D. acuminata, D. acuta, D. fortii, Phalacroma rotundatum. Dinophysis group Produce okadaic acid, Diarrheic Shellfish Poisoning. Gambierdiscus toxicusGambierdiscus toxicus is Florida's second most problematic HAB species. Gambierdiscus toxicus Gymnodinium catenatumGymnodinium catenatum has not been found in the Gulf of Mexico. Gymnodinium catenatum Gymnodinium pulchellumGymnodinium pulchellum has been associated with fish kills. Gymnodinium pulchellum Gyrodinium galatheanumGyrodinium galatheanum often confused with other small dinoflagellates. Gyrodinium galatheanum Karenia brevisKarenia brevis is the most common cause of red tides on Florida's west coast. Karenia brevis Karenia mikimotoiKarenia mikimotoi found in Florida and Texas marine waters & often confused with Karenia brevis, Florida's red tide organism. Karenia mikimotoi Pfiesteria piscicidaPfiesteria piscicida has caused numerous problems in N. Carolina and Maryland. Pfiesteria piscicida Pfiesteria speciesPfiesteria species have been found in Florida waters. Pfiesteria species Benthic Prorocentrum Group Benthic Prorocentrum Group Examples include P. belizeanum, P. hoffmannianum, P. lima, P. mexicanum Benthic Prorocentrum Group

Types of HAB PfisteriaCiguateraNSPDSPASPCyanobacteria Fish kills, human neuroeffects NeurotoxicDiarreheticAmnesic Freshwaters: fish & livestock mortalities, foul smell & taste, human health hazard

Public Health and HAB

Economic Consequences of HAB

Nutrients & Nuisance Blooms The chart shows inputs of nitrogen and phosphorus to Laholm Bay on the coast of Sweden from 1950 to Note that P inputs decreased after 1970 due to control efforts, while inputs of N increased. Eutrophication first became apparent in the bay in 1970 and became much worse in the subsequent two decades, clearly indicating that N caused the eutrophication (modified from Rosenberg et al. 1990, as printed in NRC 2000).

Macroalgal Nuisance Blooms  Ulva eg Venice Lagoon, Cork Harbour, Belfast Lough, Moreton bay D=4

Macroalgal Nuisance Blooms  Enteromorpha and filamentous algal mats eg Ria Formosa

Decreased fisheries yields  Moderate nutrient enrichment may occasionally lead to increased populations of fish but diversity may decline.  Severe nutrient enrichment leads to loss of commercially valuable fishes.  Changes in the phytoplankton community changes the food web eg small flagellates grazed by jellyfish rather than finfish e.g. Black Sea.

Decreased fisheries yields

Fish Kills  Usually Hypoxia is the reason: although fish are mobile, sometimes they are trapped by low oxygen water  Toxic algae: some of these are toxic to vertebrates inc. fish

Decreased aquaculture yields

 Large scale: China  1970’s “blue” revolution, increased aquaculture (snapper & grouper)  HAB p.a.  Summer 2000, 2700 sq mile HAB, South of Shangai $ 240 damage  Local scale: Ria Formosa

Other impacts

Other impacts related to HAB  Shellfish poisoning  Marine mammal mortalities  Marine bird mortalities  Decreased biodiversity

Loss of tourism revenues  Phaeocystis blooms form noxious smelling tide (can look like raw sewage)  1990’s HAB in N. Adriatic, resulted in beach closures and loss of summer season tourism

Seagrasses and kelp beds

 Very sensitive to effects of eutrophication.  Seagrasses and kelp often light limited  Turbidity: submerged seagrasses and kelp harmed by reduced water clarity  Epiphytic algae also cause shading  Elevated concentrations of sulphides, due to decomposing bloom organisms, can be toxic to seagrasses

The bottom-dwelling plants of a marine ecosystem that received natural rates of nitrogen addition. Note the high diversity of these plants and their spacing. The bottom-dwelling plants of a marine ecosystem that received high rates of nitrogen input. Note that there are few plant species, and that the leaves of these are covered with a thick layer of epiphytic algae.

Seagrass beds of Black Sea  North west of Black Sea had large seagrass beds  Vicinity of Danube Delta (Romania)  Increased turbidity of water and nutrient enrichment  Sea grass beds disappearing

BulgariaGeorgiaRomaniaRussiaTurkeyUkraine Fertilizer consumption in countries around the Black Sea (100 grams per hectare of arable land) after L.Mee The Green Revolution Collapse of centrally planned economy

At least 50% of the nutrients reaching the Black Sea come from agriculture The green revolution End of centrally planned economy after L.Mee

Area occupied by Phyllophora, 1950s after L.Mee

Area occupied by Phyllophora, 1970s after L.Mee

Area occupied by Phyllophora, 1980s after L.Mee

Coral destruction  Very sensitive to effects of eutrophication  Turbidity: coral reefs harmed by reduced water clarity coral.aoml.noaa.govwww.wri.org/indictrs/reefrisk.htmwww.aims.gov.au/pages/research/coral-bleaching/scr1998/scr-00.html

Coral destruction  Epiphytic algae overgrow coral coral.aoml.noaa.govwww.wri.org/indictrs/reefrisk.htmwww.aims.gov.au/pages/research/coral-bleaching/scr1998/scr-00.html

New Scientist article  January 2004  Link between agriculture in E. Australia and coral deaths on Barrier Reef

Aquifer contamination g1369.htm#meth  Acidification of lakes and streams by acid rain causes loss of freshwater fish  Aquifer contamination by NO 3 & NO 2 Methemoglobinemia (Blue baby Syndrome)  eg Faro where upper limit reached Aquifers condemned for human consumption.

Aquifer NO 3 contamination in the EU. EEA The Drinking Water Directive guideline value and the maximum allowable concentration for nitrate in drinking water are exceeded in many EU groundwater supplies. Percentage of groundwater bodies where the guide value and the MAC are exceeded: very frequently (>50 % of sites); frequently (>25 %); rarely (0–25 %); and not at all.