Term paper presentation

2. Term paper presentation • Next two weeks, no absence • Save in ppt format, name it with your name • Copy or email it to me before class (Jun 6) • Must be in English (both written and spoken) • 5 min talk + 2 min answering questions • I will pick presenter randomly

3. Term paper presentation • 10 points to your final grade • Main parts, covering taxonomy, basic biology, life history etc. (3 points) • Discussion, showing at least one new research on the species (3 points) • Clearness, flow of macro- micro-logic (2 points) • Presentation, articulate speech, timing (2 points)

4. Ichthyology Lesson 12 (chapter 18, 24, 25, 26)Ecology, adaptation and conservation Shanghai Ocean University May 31, 2018

5. Ecology • Ecology is the scientific analysis and study of interactions among organisms and their environment. • Ecology focuses on organism–environment interactions at the level of individuals, populations, assemblages, communities, ecosystems, and landscapes.

6. Individual • An individual’s life history results from differences in the allocation of energy and resources to the often-conflicting demands of maintenance, growth, reproduction, survival, and migration. • Large size is advantageous in fishes; larger fishes produce more eggs and escape more predators. • Reproduction at an early age and small size incurs a substantial cost in future reproduction; delayed reproduction means more eggs spawned but occurs at the risk of dying before ever spawning. • Theory accurately predicts the effects of mortality on reproductive age, size, interval, and allotment; individuals in populations with high adult mortality reproduce earlier and have higher fecundity and shorter reproductive intervals.

7. Geographic patterns / convergent evolution • In many families, related species living in different habitats often adopt life history patterns appropriate for that habitat, and unrelated fishes converge on suites of life history adaptations. • Mouth-brooding fishes worldwide have converged on small clutches of large eggs, slow growth rates, and protracted breeding seasons (bonytongues, marine catfishes, cichlids). • Such convergence is evidence of the importance of environmental selection factors promoting one life history over another and can be found at relatively large geographic scales.

8. Phylogenetic constraints • Phylogenetic Constraint is like a basic body plan. It can be modified (what evolution does) but it can't be fully changed. • Constraints occur when a trait is precluded from reaching, shifted away from, or slowed down in its approach to a (defined) selective optimum. • Whales did not develop gills. • Vestigial features (things like the human appendix which is a remnant of our ancestors, but is no longer used) provide evidence of common ancestry and phylogenetic constraint.

9. Polulations • A population consists of all the individuals of a particular species in a given area. • Populations grow and decline as a result of age specific reproduction and survivorship rates. • Because of dispersing larvae, migration into populations (recruitment and colonization) has a strong influence on year class strength. • Different age fishes differ substantially in size and feeding habits, making cannibalism a frequent cause of mortality. • Production is a measure of how much biomass a population produces yearly and is important in determining sustainable exploitation rates for commercial fishes. • Most fish populations produce <10 g/m2/year, most of which occurs in younger age classes.

10. Populations • Many populations are relatively isolated from other populations of the same species, which allows for genetic differentiation. • Genetically distinct populations can exist in neighboring lakes (e.g., whitefishes, sticklebacks), and Pacific salmons occur as genetically isolated stocks in adjacent rivers. • In contrast, hybridization between species results when species-specific spawning habitat is unavailable or degraded, or when disproportionate numbers of one species exist. • Hybridization is more common among freshwater fishes.

11. Assemblages • Species generally have relatively predictable habitat use patterns and predator–prey and competitive interactions (= niche). • Species that utilize similar resources in similar ways are members of a guild, as in the zooplanktivore and cleanerfish guilds on coral reefs. • Niches and guild memberships change as fish grow and their food and habitat preferences change. • Two general aspects of habitat use in fishes is that bigger individuals within a species occur in deeper habitats and that habitats in rivers and the species occupying them differ as one moves downstream.

12. Competition • Competition within and between species results when two consumers use a limiting resource. Shifts in resource use due to competition result in resource partitioning. • Competition for food resources is most common in fishes, which can lead to dramatic habitat shifts and can also influence predator–prey interactions. • Differences in resource use do not automatically imply that competition is occurring; physiological requirements, phylogenetic constraints, and differential susceptibility to predation can also produce species differences in resource use. • Introduced species frequently have strong, deleterious, competitive impacts on native species.

13. Predation • Predation can directly affect prey density through predator-caused mortality, or can have indirect effects through predator avoidance that places prey in suboptimal environments, thereby slowing individual growth and reproductive output. • Predation can also cause genetic differences in coloration, habitat use, and schooling and breeding behavior. • Introduced predators have decimated natives in many locales.

14. Synthesis: what determines assemblage structure among coral reef fishes? • The incredible diversity of coral reef fishes has fueled a debate over the relative importance of the physical environment versus biological interactions as determinants of how many and what kinds of fishes occur on any one reef. • Much of the debate focuses on whether adult populations are determined by larval mortality (recruitment limitation) or by events occurring after recruitment, such as predator–prey and competitive interactions among juveniles and adults. • It is likely that all factors contribute and that their relative importance differs temporally and spatially.

15. Interactions between fishes and other taxonomic groups • Fishes interact with non-fish taxa, competing for food and space while eating and being eaten. • The distribution of many fish species represents an avoidance of piscine, mammalian, and avian predators • In many streams, fishes are squeezed out of deep water by fish predators and out of shallow water by wading birds.

16. Herbivory • Herbivory among fishes is more common in tropical than temperate habitats; common herbivores include minnows, characins, catfishes, and cichlids in tropical fresh water, and surgeonfishes, parrotfishes, rudderfishes, blennies, and damselfishes on coral reefs. • Fishes influence plant biomass, productivity, growth form, energy allocation, and species composition; fishes also disperse seeds. • Plants have evolved mechanical and chemical defenses against herbivorous fishes. • Damselfishes on reefs “garden” algae within their territories, encouraging edible species and discouraging growth of less palatable species. Damselfish activities thus affect the diversity and distribution of algae and the many invertebrates that live in algal patches.

18. Temperate freshwater herbivores • Temperate freshwater herbivores include minnows, catfishes, suckers, pupfishes, and killifishes. During warm months when plants grow quickly, grazing minnows can crop most of the plant productivity. • During cold months, temperate herbivores commonly shift to carnivory. • Phytoplanktivory also occurs in temperate lakes, where fish such as shad can affect plankton abundance and diversity.

19. Zooplanktivores • Lake fishes prefer to eat large zooplankters, which shifts the size and species composition of the plankton to smaller zooplankton species. • Marine zooplanktivores that are active by day also preferentially eat large prey. • Avoidance of foraging fishes may be responsible for daily vertical migrations by zooplankters, for day–night differences in zooplankton assemblage composition, and for life history and anatomical traits of zooplankters and other invertebrates.

20. Trophic cascades • “Trophic cascades” describe the direct and indirect effects that predators at the top of a food web can have on trophic levels several steps below. For example, piscivorous fishes eat zooplanktivorous fishes, which feed on herbivorous zooplankton, which eat phytoplankton. Hence removing the top piscivores has the unexpected effect of increasing phytoplankton density. • Complex interactions of this nature indicate that changes in fish populations can ultimately affect water chemistry, calcium carbonate deposition, the distribution of water masses of different temperatures, and ultimately the heat budget of a lake.

21. Trophic cascades • 孟柳江 • Describe “trophic cascades” and give an example of how it works

22. Nutrient cycling and transport by fishes • Fishes can directly affect the transport and cycling of nutrients in aquatic habitats. • Phosphorus excretion by fishes is important for algal growth. • Benthic fishes disturb sediments, which increases the transfer of nutrients from the mud to the water column. • Fish bodies contain a large fraction of the nutrients in many ecosystems; nutrients are released through excretion from the gills, through defecation, and through decomposition after death. • Vertical and horizontal migrations by fishes that feed in one area and rest in another influence coral growth on coral reefs and kelp growth in kelp beds; the long-distance migrations of salmons link oceanic ecosystems with headwater streams, even influencing the growth of trees in nearby forests. • Fishes can also affect the production and distribution of substrate, as when parrotfishes grind coral into sand, or when tilefishes or breeding minnows pile rocks over their burrows or nests.

23. Influence of physical factors and disturbance • Physical factors that appear to have the greatest effects on fish assemblages include reductions in dissolved oxygen from drought and ice cover, storm induced increases in stream and river discharge, and habitat destruction on coral reefs and kelp beds from storm-caused waves. • Biological disturbances with ecosystem-wide repercussions include outbreaks of disease or population explosions of species that literally eat the food and habitat resources of a system.

24. Convergence and adaptation • The Principle of Convergence states that strong selection pressures tend to produce strong similarities in unrelated animals. Several aquatic habitats offer examples. • Mesopelagic ocean depths between 200 and 1000 m contain 750 species of fishes that are typically dark in color, with photophores, large mouths, slender teeth, reduced skeletons and squamation, long retemirabiles, low enzyme activity, and daily vertical migrations. • Bathypelagic fishes (1000–4000 m, 200 species) show stronger and more bizarre convergences, including sex reversal, extreme skeletal and musculature reduction, eye loss, longer retes, marked sexual dimorphism, and behavioral energy conservation. These characteristics are apparent adaptations to low energy availability.

26. Pelagic fishes • Oceanic, pelagic fishes swim in the upper 100–200 m of water. This is the primary region for commercial fish production and is the habitat of herringlike fishes, sauries, carangoids, dolphinfishes, mackerels, tunas, and billfishes. • Pelagic fishes are typically streamlined, silvery, and migratory, with a high proportion of red muscle for sustained swimming. • They respire efficiently and save energy by using ram-gill ventilation. • Life history differences between temperate and tropical species are influenced by seasonal and spatial food availability, and lead to dramatic differences in year class fluctuations. • Freshwater pelagics have converged on many traits with oceanic species.

28. Polar Arctic and Antarctic regions • The polar Arctic and Antarctic regions lie above 60° latitude. The Antarctic has more endemic, specialized fishes, half of which are in the icefish suborder Notothenioidei. Antarctic fishes avoid freezing because their blood contains antifreeze compounds. • Channichthyids are unusually pale because they lack hemoglobin and myoglobin. Some notothenioids have evolved neutral buoyancy via reduced skeletal mineralization and increased lipid deposition. • Arctic fishes have converged on similar traits.

30. Desert fishes • Desert freshwater fishes live on almost all continents in regions where water scarcity creates extreme conditions. • Desert fishes often possess accessory respiratory structures for using atmospheric oxygen, and have a life cycle that includes a resting stage during droughts, either involving a diapausing egg or an estivating adult. • In addition to low oxygen, desert fishes often encounter extremes of salinity and alkalinity. The deserts of the southwestern USA and western Mexico have a surprising diversity of endemic fishes, many of which are threatened.

31. Desert goby

32. Fishes that inhabit high-energy zones • Fishes that inhabit high-energy zones such as the wave-swept intertidal zone or steep stream beds have converged upon a body shape that is depressed, paired fins that are expanded, a suction device, subterminal mouths, and small body size. • All these traits appear to facilitate the holding of position on the bottom despite strong water flow.

34. Cave fishes • Cave fishes live in lightless, freshwater environments where food is scarce. • Cave-adapted forms typically have reduced eyes, pigmentation, and squamation; low metabolic activity and reproductive rates; low population densities; and increased chemosensory and lateral line development. • Their biology makes them especially vulnerable to habitat disturbances. • Cave-dwelling fishes have converged on many of the traits evolved by deepsea fishes, probably in response to food and light scarcity.

36. Conservation • Extinction rates have increased dramatically in the past 50 years due to human activities; present rates are 1000 times greater than average and 10–100 times greater than during past periods of mass extinction. • About 20% of the world’s 9000 species of freshwater fishes are either extinct or nearly so; 40 fishes have gone extinct in North America in the past century and the rate is accelerating. • Marine fishes are less threatened because of their wider distributions, although many commercially important species are showing serious declines.

37. Causes of fish extinction • Major causes of biodiversity loss are habitat loss and modification, species introductions, pollution, commercial exploitation, and global climate change. • Habitat loss occurs through modification of bottom type, as happens during dredging, log removal, coral or gravel mining, trawling, and from silt deposition due to deforestation of the surrounding watershed. • Other causes of habitat loss include channelization of streams and rivers, dam building, and water withdrawal.

38. Invasive species • Introduced species affect native species because introduced fishes are often freed from their evolved population controls, and natives are evolutionarily unprepared for the introductions. • Predation by and competition and hybridization with introduced species are common results, as is the introduction of new pathogens. • The introduction of Nile Perch into Lake Victoria has led to the possible extinction of hundreds of species of endemic cichlids that previously supported an important local fishery.

39. Environment monitor • Chemical, nutrient, and sediment pollution all have adverse effects on fishes; predation on fishes by birds and mammals links aquatic and terrestrial ecosystems via such pollution. Fishes can therefore serve as valuable indicators of environmental health.

40. Overfishing • Approximately 40% of the commercial marine fish species important to the USA are exploited at unsustainable rates. The Pacific Sardine, Peruvian Anchoveta, and Giant Totoaba were all very abundant commercial species that have essentially disappeared due largely to overfishing. Some species reductions are the indirect result of other fisheries. • Bycatch in the shrimp fisheries of the Gulf of Mexico greatly reduces the available stocks of Red Snapper and Spanish Mackerel, among other species. • Coral reef fishes are commercially exploited for the home aquarium trade, which has led to reef destruction and species depletion in many places. Few such fishes live more than a few months in captivity.

41. Climate change • Greenhouse gases have been pumped into the atmosphere at increasing rates during the past century, raising the prospect of global warming, sea level rises, ocean current shifts, and major climatic changes such as drought, floods, and cyclonic storms. • Global warming has and will alter the distribution, abundance, reproductive timing, trophic relationships, and migration patterns of fishes through its impacts on water temperature, rainfall patterns, freeze–thaw cycles, oxygen availability, heat budgets, oceanic currents, primary productivity, ocean acidification, and metabolic processes. • Coral reef ecosystems have been especially degraded due to slightly elevated temperatures, and prospects for the future are not promising. Major shifts in freshwater fish distribution and diversity would also occur.

42. Solution • Biodiversity loss is a symptom of environmental deterioration on a global scale. • Solutions to environmental problems include ecosystem and landscape preservation, development of reserves, habitat restoration, and captive breeding of endangered species. • None of these efforts will be successful if human population growth and overconsumption are not curtailed.

43. Your final paper is due on Jun 14th • Don’t forget your name • Double side • Double line space • Use subtitles • Introduction • Physical description … • Flow of your logic at macro and micro level • Need English editing • Choose the correct words, e.g. intramuscular bone, not thorn • Tense and consistent verb… • Avoid redundancy • Spend more time on it!