Conservation of Aquatic Ecosystems Class 10 Presentation 2

Why aquatic ecosystems? 71% of earth covered by water 71% of earth covered by water Fresh water systems compared to marine and terrestrial ecosystems most impacted by humans Fresh water systems compared to marine and terrestrial ecosystems most impacted by humans Marine fish harvests have reached max Marine fish harvests have reached max Huge decline in large fish numbers (sharks, barracuda, marlin etc) Huge decline in large fish numbers (sharks, barracuda, marlin etc) Useful source of food, medicine, energy, minerals. Useful source of food, medicine, energy, minerals. Marine biota very diverse:only 5% of animal phyla inhabit only land vs. 64% of animal phyla inhabit seas Marine biota very diverse:only 5% of animal phyla inhabit only land vs. 64% of animal phyla inhabit seas

Unusual fact Nearly half of the photosynthesis in the world is accounted for in a microscopic organism found on the first 200 m of ocean surface: Prochlorococcus Nearly half of the photosynthesis in the world is accounted for in a microscopic organism found on the first 200 m of ocean surface: Prochlorococcus Over 20,000 in each drop of sea water Over 20,000 in each drop of sea water Only discovered in 1988 Only discovered in 1988 Berkeley Lab

Habitat features important for fresh water systems Substrate: Substrate: sand & silt: poorest habitat, because few attachments sites for periphyton and consumers sand & silt: poorest habitat, because few attachments sites for periphyton and consumers Boulders, rocks, gravel: better because larger surface area, more attachment sites, provide cover, refuge, diverts force of moving water. Boulders, rocks, gravel: better because larger surface area, more attachment sites, provide cover, refuge, diverts force of moving water.

Other habitat features important for fresh water systems Shore vegetation: siltation, water seepage, climate Shore vegetation: siltation, water seepage, climate Topography, climate, parent material, soil type, Topography, climate, parent material, soil type,

Fresh water Lotic systems: flowing water ecosystems Lotic systems: flowing water ecosystems 2 dominant habitat features: 2 dominant habitat features: Riffles: sites of primary production, have periphyton: which are a community of organisms composed of diatoms, blue-green, & green algae, & aquatic mosses. Periphyton is ephemeral moves down stream Riffles: sites of primary production, have periphyton: which are a community of organisms composed of diatoms, blue-green, & green algae, & aquatic mosses. Periphyton is ephemeral moves down stream Pools: catch basins below riffles, lower water flow, biomass accumulates, consumers accumulate Pools: catch basins below riffles, lower water flow, biomass accumulates, consumers accumulate UBC Photo

Fresh water: Lentic systems Lake habitat Lake habitat Little affected by internal currents Little affected by internal currents More by prevailing winds More by prevailing winds Cells of water set in motion by wind, important for transport of food & heat vertically in water column Cells of water set in motion by wind, important for transport of food & heat vertically in water column Water density changes with temp Water density changes with temp Mobile aquatic organisms move with changes in temp and water density like terrestrial organisms move to changes in vegetation cover. Mobile aquatic organisms move with changes in temp and water density like terrestrial organisms move to changes in vegetation cover. Organisms move to different parts that allow them to benefit in growth, reproduction and survival Organisms move to different parts that allow them to benefit in growth, reproduction and survival

Fresh water: Wetland systems Defined as “transitional between terrestrial and aquatic systems where the water table is at or near the surface or land is covered by shallow water” Defined as “transitional between terrestrial and aquatic systems where the water table is at or near the surface or land is covered by shallow water” Cover about 6% of earth, but disproportionate amount of benefits (hunting, fishing, trapping, timber, water, agriculture) Cover about 6% of earth, but disproportionate amount of benefits (hunting, fishing, trapping, timber, water, agriculture) Disproportionate amount of threatened and endangered spp are wetland dependent Disproportionate amount of threatened and endangered spp are wetland dependent

Conservation challenges: freshwater systems Affected by: Affected by: Physical alteration (dams, channels, development Physical alteration (dams, channels, development Chemical alteration: nutrients, pollution Chemical alteration: nutrients, pollution Introduction of exotic organisms Introduction of exotic organisms

Future Improve productivity of water use Improve productivity of water use Change our goal from use of water to improved social and individual well- being per unit of water used Change our goal from use of water to improved social and individual well- being per unit of water used This means using market and regulations to cause change. This means using market and regulations to cause change.

Eutrophication: Effects of nutrients Most important nutrient: phosphorus Most important nutrient: phosphorus Chain reaction: Chain reaction: Increase in biomass of attached algae & submersed macrophytes, they then decrease as blue green algae and phytoplankton increase and block light. Dead organisms use oxygen, result in fish kills, but minnows and carp increase initially, reducing zooplankton, which causes increase in phytoplankton, further reducing light. Result: biological community altered, water quality declines (less valuable for drinking, recreation and food)

Acidification Lower pH results in lower reproduction by fishes, amphibians & aquatic invertebrates, also direct mortality Lower pH results in lower reproduction by fishes, amphibians & aquatic invertebrates, also direct mortality Lower pH causes changes in ions, esp. Al, Pb, and Cd. They precipitate out at low pHs. Al can bind to gills of fish killing them. Lower pH causes changes in ions, esp. Al, Pb, and Cd. They precipitate out at low pHs. Al can bind to gills of fish killing them. Al can bind to P as it precipitates, making it less available as a nutrient for organisms. Al can bind to P as it precipitates, making it less available as a nutrient for organisms. Lower fish population can result in increase in invertebrate population released from predation. Lower fish population can result in increase in invertebrate population released from predation.

Marine ecosystems Coral Reefs: combine elements of structure, nutrients (esp. Ca), water quality and light to create favourable environment for life Coral Reefs: combine elements of structure, nutrients (esp. Ca), water quality and light to create favourable environment for life Hydrothermal vents: unique environment and life forms (some very ancient) Hydrothermal vents: unique environment and life forms (some very ancient) Benthic (sea bottom) communities: sediment grain size related directly to diversity of organisms, structure in soft sediments important for diversity of life. Benthic (sea bottom) communities: sediment grain size related directly to diversity of organisms, structure in soft sediments important for diversity of life.

Causes of marine habitat degradation Physical structure change: Physical structure change: Use of dynamite on coral reefs Use of dynamite on coral reefs Bottom trawling nets: more complex habitat is more severely affected. Bottom trawling nets: more complex habitat is more severely affected. Mariculture, land development Mariculture, land development Land events: sedimentation Land events: sedimentation

Causes of marine habitat degradation Chemical Chemical Eutrophication Eutrophication Pollutants, pesticides, radioactive waste Pollutants, pesticides, radioactive waste Mariculture, some changes direct: waste, disease; others indirect: genetic (out breeding depression of escaped farmed salmon), change in predator population: sea star and mussel cultivation) Mariculture, some changes direct: waste, disease; others indirect: genetic (out breeding depression of escaped farmed salmon), change in predator population: sea star and mussel cultivation)

Human caused changes in population Over harvest: direct Over harvest: direct Over harvest indirect: affect on other organisms when foundation spp reduced drastically: e.g. sea otter Over harvest indirect: affect on other organisms when foundation spp reduced drastically: e.g. sea otter Trophic effects and interconnections new area of study Trophic effects and interconnections new area of study

Past Seas were common property, countries competed for fish thousands of miles from home Seas were common property, countries competed for fish thousands of miles from home 1982 UN adopted Convention on the Law of the Sea, allowing coastal countries to claim 200 nautical mile exclusive economic zone, included most continental shelves 1982 UN adopted Convention on the Law of the Sea, allowing coastal countries to claim 200 nautical mile exclusive economic zone, included most continental shelves

Past This placed responsibility of control on coastal country. This placed responsibility of control on coastal country. Most used subsidies to grow fishing industry Most used subsidies to grow fishing industry Convention called for allowing other countries access to resources not used by local country: resulted in push by local countries to use all available fish resources Convention called for allowing other countries access to resources not used by local country: resulted in push by local countries to use all available fish resources Over fishing warnings did not occur because we did not understand threshold effects, poor population modelling, cheating on regulations and lying on fish catch statistics Over fishing warnings did not occur because we did not understand threshold effects, poor population modelling, cheating on regulations and lying on fish catch statistics

Recent problems Fishing down the food web Fishing down the food web Table fish (cod, snapper, tuna) usually feed on small pelagic fish (herring, anchovies, sardines) (trophic level ) Table fish (cod, snapper, tuna) usually feed on small pelagic fish (herring, anchovies, sardines) (trophic level ) However, very large quantities of small pelagic fish (trophic level 3) being caught to provide feed for animals and farmed fish However, very large quantities of small pelagic fish (trophic level 3) being caught to provide feed for animals and farmed fish

Future Focus on herbivorous fish for farming: tilapia, mussels, clams Focus on herbivorous fish for farming: tilapia, mussels, clams Ecosystem based management like in forestry: understand resilience and resistance: phase out fishing gear that destroys habitat, implement marine reserves, abolish subsidies, enforce gear used to reduce by-catch, reduce fishing fleet Ecosystem based management like in forestry: understand resilience and resistance: phase out fishing gear that destroys habitat, implement marine reserves, abolish subsidies, enforce gear used to reduce by-catch, reduce fishing fleet