Aquatic Ecology Objectives Discuss biodiversity and endangered species. Examine the needs of all aquatic environments. Discuss the three types of aquatic environments. Identify various zones in a lake. Analyze the trophic stages of a pond, lake, or stream. Discuss and define biological indicators. List sensitive and tolerant groups. Describe how to collect samples. Identify macro invertebrates in your sample. Identify and determine the quality of a local stream. BIODIVERSITY PROTECTION Hunting and Fishing Laws By 1890’s, most states had enacted some hunting and fishing laws. General idea was pragmatic, not aesthetic or moral preservation. White-tailed deer Wild turkeys Wood ducks Endangered Species Act Established in 1973. Endangered are those considered in imminent danger of extinction. Threatened are those likely to become endangered, at least locally, in the near future. Vulnerable are those that are naturally rare or have been locally depleted to a level that puts them at risk. Endangered Species Act Cont’d ESA regulates a wide range of activities involving Endangered Species: Taking (harassing, harming, pursuing, hunting, shooting, killing, capturing, or collecting) either accidentally, or on purpose. Selling Importing into or Exporting out of the U.S. Possessing Transporting or Shipping Endangered Species Act Cont’d Currently, the U.S. has 1,300 species on its endangered and threatened lists, and 250 candidate species waiting for consideration. Number reflects more about human interests than actual status. Invertebrates make up 75% of all species, but only 9% worthy of protection. Listing process is extremely slow. Recovery Plans Once a species is listed, USFWS is required to propose a recovery plan detailing the rebuilding of the species to sustainable levels. Total cost of all current plans = $5 billion. Opponents have continually tried to require economic costs and benefits be incorporated into planning. Reauthorizing ESA ESA officially expired in 1992. Proposals for new ESA generally fall into two general categories: Versions that encourage ecosystem and habitat protection rather than individual species. Safe Harbor policies that allow exceptions to critical habitat designations. (Economic Considerations) What are the basic needs of aquatic biota? CO2 O2 Sunlight Nutrients- food & minerals What factors influence the availability of those basic needs? Substances dissolved in water- Nitrates, phosphates, potassium, O2 Suspended matter- (silt, algae) can affect light penetration Depth Temperature Rate of flow Bottom characteristics (muddy, sandy, or rocky) Internal convection currents Connection to or isolation from other aquatic ecosystems. Types of Aquatic Ecosystems Freshwater Ecosystems Transitional Communities Standing Water- lakes & ponds Moving Water- rivers & streams Estuaries Wetlands- bogs/fens, swamps, marshes Marine Ecosystems Shorelines Barrier Islands Coral Reefs Open Ocean Types of Aquatic Systems Rivers & Streams Lakes & Ponds Wetlands Estuaries Groundwater Marine system Freshwater Ecosystems Usually 0.005% salt Some exceptions: Great Salt Lakes- 5-27% salt Dead Sea- 30% salt Moving water- high elevations; cold; high O2; trout; streamlined plants Standing water- lower elevations; warmer; less O2; bass, amphibians; cattails, rushes Lentic Zones Lotic Environments Lotic Environments Lakes and Ponds Critical differences from other freshwater systems Longer residence time Typically not shaded with most of the surface area exposed to sunlight Florida lakes are typically shallow and well mixed Florida lakes are often highly colored, but can have light reaching much of the bottom Photo by Bill Wade Watershed / Lake Area Ratio Watershed area relative to lake area will influence the residence time of water in the lake. This ratio is also a factor in the nutrient loading to the lake Lake Habitat Zones Lake Littoral Zone Functions Intercepts Nutrients Refuge from Predators Nursery for Fish Eutrophic Southern Lake Oligotrophic Northern Lake Lake Limnetic/Pelagic Zone Functions Plankton Zooplankton Lake Limnetic / Pelagic Zone Submerged Aquatic Vegetation (SAV) Nutrient uptake Sediment stabilization Habitat Oxygen production Pond Food Web Algae/Plants Fish Nutrients Grazers Nutrients Algae/Plants Grazers Fish Relationship Between Nutrients and Pond Productivity Nutrients Nutrients Nutrients Nutrients Algae/Plants Grazers Algae/Plants Algae/Plants Grazers Grazers Algae/Plants Nutrients Algae/Plants Grazers Grazers Fish Fish Fish Fish Fish Habitat/Environmental Impacts Low nutrients Low primary productivity Low grazers and insects Low fish production Clear water Sandy/low organic matter on bottom Moderate nutrients TROPHIC STATE Increased primary productivity More grazers and insects More fish production Moderate water clarity More aquatic plants Some organic sediment accumulation HighTROPHIC nutrients STATE High primary productivity Large number of grazers and insects Moderate fish production Low water clarity, or Clear with aquatic plants High organic sediment accumulation Trophic State Change Nutrients & Productivity Sediment & Accumulation Species Shifts Species Richness How is a lake stratified and what lives in each level? Epilimnion- upper layer of warm water; high light & O2; ex: water striders, phyto- & zooplankton, fish Thermocline (mesolimnion); middle layer; medium light & O2; ex: phyto- & zooplankton, fish Hypolimnion- lower layer of cold water; lower light & O2; ex: fish Benthos- bottom level; no light & little O2; ex: anaerobic bacteria, leeches; insect larvae Littoral- near the shoreline; cattails, rushes, amphibians, etc. Transitional Communities ESTUARIES Where freshwater dumps into ocean Brackish (less salty than seawater) Has rich sediments that often form deltas Productive & biodiverse Organisms adapted to varying levels of salinity as tide ebbs & flows “Nursery” for larval forms of many aquatic species of commercial Transitional Communities WETLANDS Land saturated at least part of the year Swamps- have trees like bald cypress; high productivity Marshes- no trees; tall grasses; high productivity Bogs/Fens- may or may not have trees; waterlogged soil with lots of peat; low productivity Swamp Marsh Fens- fed by groundwater & surface runoff Bogs- fed by precipitation Bog Fen Importance of Wetlands Highly productive- get lots of sunlight, ↑ plants = ↑ animals Nesting, breeding ground for migratory birds Slows flooding by absorbing runoff Silt settles, making water clearer & nutrient rich Trap & filter water Natural chemical rxns neutralize and detoxify pollutants Gives H2O time to percolate thru soil & replenish underground aquifers. Threats- artificial eutrophication (see slide 13), draining, sedimentation via construction “Nature’s Septic Tank” Marine Ecosystems SHORELINES Rocky coasts- great density & diversity attached to solid rock surface Sandy beaches- burrowing animals Threats- due to hotels, restaurants, homes on beach, more plant life destroyed, destabilizing soil, susceptible to wind & water erosion Insurance high; danger of hurricanes, erosion Build sea walls to protect people but changes & endangers shoreline habitat Marine Ecosystems BARRIER ISLANDS Low, narrow offshore islands Protect inland shores from storms Beauty attracts developers = developers destroy land New coastal zoning laws protect future development MARINE ECOSYSTEMS CORAL REEFS Clear, warm shallow seas Made up of accumulated calcareous (made of calcium) skeletons of coral animals Formation depends on light penetration. Have a symbiotic relationship with algae Very diverse, abundant (rainforests of sea) Threats- destructive fishing (cyanide & dynamite to stun fish), pet trade; about 3/4ths have been destroyed What factors can alter aquatic ecosystems? Natural Successionnormal cycle of pond becoming forest Artificial Successionhumans add N & P to water via fertilizer & sewage causing succession to happen faster = EUTROPHICATION What factors can alter aquatic ecosystems? Humans! Find food Recreation Waste disposal Cooling of power plants Transportation Dams, canals Algae and Microinvertebrates Can’t be seen with the naked eye Cyanophyta Chlorophyta Euglenophyta Heterokontophyta Xanthophyceae Chrysophyceae Bacillariophyceae Phaeophyceae Oomycetes Rhodophyta Pyrrhophyta Rotifera Ectoprocta/Bryozoa Arthropoda Crustacea (superclass) Cladocera (suborder) Copepoda (order) Chelicerata (subphylum) Arachnida (superclass) Acari (order) Phytoplankton Phytoplankton – microscopic plants and some types of bacteria which obtain their energy via photosynthesis. Important to the ecosystem because Part of the primary producing community Assist in recycling elements such as carbon and sulfur which are required elsewhere in the community. Phytoplankton Basis for aquatic food chain b/c major primary producers Huge impact on global primary production Estimated at 105 – 106 g C/year More abundant in well-lighted areas with higher temperatures Relatively unspecialized physiology, but are evolved to maintain buoyancy Very little competitive exclusion May be unicellular or multicellular Phytoplankton Asexual reproduction keep numbers high Cyanobacteria can double several times/day Diatoms are slower, but can double every 1-2 weeks Phytoplankton Phylogenetically diverse Important groups: cyanobacteria dinoflagellates euglenoids green algae diatoms Diatoms: Order Centrales Characterized by centric and often circular form Note also the numerous punctae (pores) Diatoms Gyrosigma obtusatum Pleurosira laevis Nitzschia levidensis Dinoflagellates Phylum Pyrrhophyta “Whirling flagella” Habitat: Mostly marine, some freshwater Notes: Unicellular protists 2 dissimilar flagella Many are photosynthetic Dinoflagellates Notes: Heterotrophic dinoflag feed on diatoms or other protists Marine “blooms” Red tides Rotifers Phylum Rotifera “Rotating wheel” Habitat: Fresh water Notes: Heterotrophic Corona of cilia provide movement and means to move food toward the mouth. Rotifers Notes: Sessile, anchors itself with foot May enter dormancy and form cyst when env. conditions unfavorable Cysts last up to 50 years Bryozoa Phylum Ectoprocta (=Bryozoa) “Moss animals” Habitat: Marine and both lotic/lentic freshwaters Notes: Sessile; can be epiphytic, epilithic or epidendric Colonial; a number of clones inhabit one structure Extend ciliated tentacles to filter food from water Often host a number of smaller organisms Bryozoa Cladocera Phylum Arthropoda, Superclass Crustacea, Suborder Cladocera Water fleas or Daphnia Habitat: widespread; very important in lentic habitats Notes: Uses antennae to swim Many populations react to diurnal cycles, making vertical migrations each day May be predacious or herbivorous Head varies considerably from rounded to hooded but eye spot is always distinctive Body laterally compressed Cladocera Notes Parthenogenetic: most eggs are diploid females (asexual repro) occasional diploid males fertilize haploid eggs produced by females for sexual reproduction Copepods Phylum Arthropoda, Superclass Crustacea, Order Copepoda Habitat: widespread in marine and fw; may be benthic or pelagic Notes: may be parasitic, predacious or detrivorous often seen carrying egg sacs on both sides develop through several stages as immature copepods before reaching maturity Characterized by conspicuous 1st pair of antennae and single anterior eye Acari (Water Mites) Phylum Arthropoda, Subphylum Chelicerata, Superclass Arachnida, Order Acari Habitat: most abundant in lotic waters Notes: Have 6 legs when young, 8 when mature Many are parasitic but a few are predaceous Possess no antennae Related to terrestrial spiders Macroinvertebrates Show bioindicators pdf.