Marine Vertebrates And Invertebrates Response To Climate Change Biology Essay

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In recent years the global climate has changed significantly and is expected to change more in the future. For instance, over the past 60 years the East Australian Current has moved pole ward by 350km (a change of 5.833km/year) (Ling et al., 2009) and the Antarctic peninsula air temperate has increased by 0.5°C per decade (Nicol et al., 2008) (making it one of the fastest warming places on earth). Overall, the global climate has increased by 0.3-0.6°C in the last 100 years with the most rapid warming of that period occurring between 1925-1944 and 1978 and 1997 (McCarty, 2001). These changes in climate have effects upon ecosystems, notably changes in species dynamics; such as phenology changes and range shifts. This paper discuses range shifts, this is where a species' geographical location changes. This can occur by either a change in habitat boundary (expanding or contracting) or by the entire habitat area moving position. Observations of species movement in response to climate changes are relevant to not only today's climate but to predicting future changes. For example, North Sea temperatures are predicted to increase by 0.5 - 1°C by 2020 and 1-2.5°C by 2050 (Perry et al., 2005) and so by monitoring changes of species in the North Sea today, the response to future climatic changes may also be forecasted.

With temperature increasing in both the air and oceans (Loarie et al., 2009) the response of organisms to this change varies with species and location. As global temperature changes, local climates will also change (fig.1). Species must move to stay within their required climate, resulting in a range shift, if they did not shift they would be threatened by extinction (Hansen et al., 2006). A warming of 3°C over the 21st century is thought to be able to cause a mass extinction of 60% of species globally, with historical mass extinctions occurring with an increase of 5°C (Hansen et al., 2006). Therefore, to survive species must move position by a range shift. Predictable range shifts are defined as any changes in the distributions of species that are not human-assisted (Sorte et al., 2010), this covers expansion, contraction, or both, of a species range within an area. Species which undergo range shifts do not often move at a constant rate. The edge of expansion of the range boundary and the edge of contraction will move differently, this reflects the mechanisms the species use to determine the rate of their range shifts (Loarie et al., 2009).

These changes in range have impacts upon the larger biological system; disturbing species balances and introducing new species into areas. These impacts will not be covered in this paper, but are a substantial effect of climate change and organism responses.

Regardless of the global significance, the response of marine organisms to climate change is still largely unknown (McCarty 2001) with the major changes of the oceanic ecosystems occurring in the last 40 years (Loarie et al. 2009).

Figure 1. Pole-ward migration rate of Isotherms by (km/decade). A and B show observed changes whereas C and D show predicted changes. Numbers in the upper right are the global mean (with the exclusion of the tropical band) (Hansen et al., 2006).

Although marine species are studied less than terrestrial organisms; ongoing studies have shown that 75% of range shifts of marine organisms were pole ward with these shifts considered the 'next frontier' of climate change research (Sorte, Williams and Carlton 2010). This is partly due to the fact that marine shifts have been shown to be occurring at a greater rate than terrestrial shifts, the average rate of marine shifts being 19km per year, compared to 0.6km per annum for terrestrial movements in range (Sorte et al. 2010).

In spite of its global significance, the most change in climate has been seen in the high latitudes (Loarie et al. 2009). In the Arctic and Antarctic the environment is more sensitive to change and as their ecosystem is less stable than those at lower latitudes, polar organisms respond faster to climate changes (Walther et al., 2002). Movements of many marine species have been noted to be pole ward (Parmesan 2006), toward higher latitudes with species found throughout the world's oceans have been seen to be responding to climate change. For example, North Sea fish species have moved pole ward (Perry et al. 2005) boreal plankton has moved (Greene et al. 2008) and sea urchins found on the Southeast coast of Australia have shifted (Ling et al. 2009).

The problem facing scientists today is how fast are marine organisms moving in response to climate change? The range and boundary changes in both marine vertebrates and invertebrates pose significant effects on marine ecosystems (for example, disruption of habitats and food webs) and so by understanding the rate of shift, other consequences of climate change may also be understood. The aim of this paper is to gather information on the rate of movement for both marine vertebrates and invertebrates globally and to then compare the rates against each other to determine which is moving faster.

A larval stage in invertebrate development, makes these organisms easier to transport by currents and slight changes in environment while marine vertebrates tend to have a slower response to changes (Parmesan 2006). Many marine vertebrates and some marine fishes have evolved a larval stage in their development, these larvae have the capability of being transported large distances, colonize new areas and to move away from an overcrowded or unsuitable (Thorson, 1950). The pelagic life of many invertebrate larvae means that species can be widely dispersed making them better adapted to movements in response to climate change. For example, as ocean currents change position the larvae transported by said currents will also change in habitat range, resulting in a fast response to changes in climate (Thorson, 1950). Whereas marine vertebrates, with the exception of some fishes, do not undergo a larval development stage in their life history (Hiddink, Unpublished). This makes their transport by currents harder than that for invertebrates and so response to climate change slower. Also, many vertebrate species are migratory, cetaceans travel 1000's of kilometers making monitoring of these animals harder, but also meaning they need to respond to different rates of climate change in different areas (McCarty, 2001). The outcome of which is that marine invertebrates are moving faster in response to climate change than vertebrate species.

As mentioned previously, studies on the rates of range shift for marine organisms are sparse compared to those for terrestrial species. Meaning there is a lack of information on the subject and consequently limitations within this paper. It must also be noted that many of the species studied are coastal with open-ocean species being under-represented (Sorte et al., 2010) However, by accumulating existing data then gaps within the records will be clearer and areas of further studies more pronounced. Sorte et al. 2010 assumed that marine populations were more open than terrestrial populations, making them more adaptive to change; nevertheless, predicting spread rates of marine organisms is still very difficult and usually results in large error bars. An accurate prediction of shift rates is needed to understand adjustments induced by climate change globally (Sorte et al., 2010).

You are mixing information between and within paragraphs, you need to sit down and organize the information you present by carefully considering what equivalent information should be grouped together.

Method and Materials

Research for this paper was compiled by an extensive literature search using scientific databases such as Web of Science and Google Scholar. Search criteria included key words such as "range shift", "boundary change" and other variations on response to climate change. Other searches were conducted with phrases such as 'response to climate change' and some searches were undertaken for specific species (for example polar bear, Ursus maritimus).

Once the literature was compiled data was interpreted into changes in kilometers per year, this occurred by either a calculation from data within articles or by determining distances using maps (where 1° of latitude is approximately 110km). This was done to ensure all rates of range shift would be comparable to each other. If no range shift could be calculated then species were included in the overall discussion but not in the comparison.

Rates of marine vertebrates and invertebrates were then examined and compared. The comparison was species to species but also between taxonomic groups (for example fishes compared to birds). Average rates were taken for invertebrates and vertebrates by way of box plot data and statistical tests (which ones?!?!?) for averages. These averages were then examined to answer the original hypothesis.

I would expect this section to be much longer, with more detail on what you looked for exactly.

Findings

As noted, there are large gaps within the existing knowledge around this subject, especially for marine vertebrates as they are harder to monitor. This lack of data means that the responses of many species are still unknown; however models may be produced to predict changes once further information has been gathered. Text belongs in introduction

Changes in Climate Text belongs in introduction

To fully understand a species response to climate change, changes in climate must first be understood. Range shifts studies date back to the 1700's (Parmesan, 2006) with climate change being shown to be the primary source of over 70% of range shifts which have been studied (Sorte et al., 2010). As changes in temperature not only affect the organisms environment but their metabolic rate, population and community composition (McGowen et al., 1998). Changes in environment by climate change occur via sea level, exposure of organisms in intertidal areas, currents, movement of larvae, erosion and therefore substrate structure and light intensity. Along with water stratification and nutrient cycling meaning effects upon productivity, these all effect population and community dynamics over time (McGowen et al., 1998). Meaning that a change in temperature does not only make the local climate warmer or cooler but adjusts many environmental variables, which then have an effect upon the organisms within said areas.

There have been long-term measurements of sea surface temperature across the globe, most measurements started up in the early 20th century (McGowen et al., 1998) along with a shorter time (since 1940's) of studies of biological activity (measurements of zooplankton, fish and kelp communities). By this long-term study of sea surface temperature a global average and a general trend can be established (fig 2).

Figure 2. Change in SST (sea surface temperature) relative from 1870-1990 and 2001-2005 (A). B shows means in SST in the East and West Equatorial Pacific relative to 1870-1990 means. (Hansen et al., 2006).

As shown in fig 2, the global average SST has been increasing steadily over the past century, although averages and anomalies have varied significantly between years and decades (McGowen et al., 1998). This has resulted in an increased number of El Nino and El Nina events which have not only increased in velocity but also in strength (Loarie et al., 2009). These events have impacts upon not only Pacific ecosystems and distributions of species but the global ocean temperature (Hansen et al., 2006). Anomalies such as these have been escalating since the beginning of the century (fig.3).

Figure 3. Surface temperature anomalies relative to 1951-1980. A shows global annual mean anomalies and B shows temperature anomalies for the first half of the 21st Century (2000-2005) (Hansen et al., 2006).

By using such data models of predicted global temperature change have been made (fig.4), along with observational data from meteorological stations global temperature is shown to be increasing. By 2020 temperature is predicted to have increased by over 1°C since 1980 (Hansen et al., 2006).

Figure 4. Spatial variability in surface warming. Temperature compared to 1951-1980 mean. Data from: from http://data.giss.

nasa.gov/gistemp/maps/. (Brierley and Kingsford, 2009).

These changes in temperature, although they seem small on a yearly basis, will have impacts upon marine species. Changing their environment and causing them to shift.

Response of Vertebrates

Put in world map to show locations (APPENDIX!) and table of species

Marine vertebrates are some of the most complex organisms living today. Classified under the subphylum Vertebrata, there are seven main classes; Agnatha, Amphibia, Aves, Chondrichthyes, Mammalia, Osteichthyes and Reptilia, with fishes alone taking up three of these classes (Agnatha, Chondrichthyes, and Osteichthyes) (Burger, 1989). Globally there are 105 species of jawless fish (Agnatha), 928 species of rays and sharks (Chondrichthyes) and an estimated 27,712 species of bony fish (Osteichthyes). Unsurprisingly, fish species account for over 90% of all marine vertebrate species (and 50% of all vertebrate species) (Hiddink, Unpublished).

Such a large number of fish species within the world's oceans means that many species are readily available for monitoring, particularly those located within fisheries. For example, fish stocks within the North Sea are closely observed and so any change in range will be easily determined. Meanwhile, migratory species will be harder to monitor changes in range and so little data is readily available; predominantly data for such species covers broad aspects - run timings and boundary spread for example - rather than data on the rate of range changes.

LINK THE PARAGRAPHS

The other classes of Reptilia, Aves and Mammalia (reptiles, birds and mammals) hold 3082, 9842 and 4835 species respectively and have varying degrees of reliance on the marine environment. For example, birds, such as penguins, live in terrestrial environments but depend on the sea for food whereas cetaceans live solely within the marine environment (Hiddink, Unpublished). The varying degrees of dependence upon the ocean results in a varying degree of adaptation and responsiveness to the changing marine environment, for example a fur seal, who spends time foraging in the water along with hauling out on land, will respond to both terrestrial and marine changes whereas a gray whale who spends their entire life submerged will response primarily to marine changes (Burger, 1989).

Cetaceans are particularly hard to monitor as they spend their lives within the ocean and many migrate large distances, the humpback whale (Megaptera novaeangliae), for example, can travel 12,000 kilometers in one year (Vigness-Raposa et al., 2010) making the evaluation of range shift harder than for sedentary animals. Pinnipeds, unlike cetaceans, spend time hauled out along with time in the oceans, so even though they migrate periods of haul-out make the monitoring of a species range much easier. This said little data has been collected for pinnipeds and other marine mammals and reptiles, with more emphasis being on marine birds and fish.

Species

Data for 14 species of fish, 10 bird species and three mammal species was collected, with 12 of these species having no data for rate of range shift (Table 1).

Table 1. Data for vertebrate species, location, distance moved, time period and rate of movement.

Taxon

Species

Location

Rate (km/year)

Distance (km)

Period

Reference

Birds

Egretta garzetta

Britain

?

?

?-1996

Musgrove (2002)

 

Larus delawarensis

Canada

7.4

275

1965-2002

McAlpine et al. (2005)

 

Larus hartlaubii

South Africa

45.8

550

1990-2002

Crawford et al. (2008)

 

Phaethon rubricauda

Australia

?

?

?

Dunlop & Wooller (1986)

 

Phalacrocorax coronatus

South Africa

29.6

355

1991-2003

Crawford et al. (2008)

 

Puffinus mauretanicus

Western Europe

?

220

?

Wynn et al. (2007)

 

Pygoscelis adeliase

Antarctica

?

3

?

Taylor & Wilson (1990)

 

Sterna anaethetus

Australia

?

?

?

Dunlop & Wooller (1986)

 

Sterna dougallii

Australia

?

?

?-1982

Dunlop & Wooller (1986)

 

Sterna forsteri

California USA

?

380

?-1962

Gallup (1963)

Fishes

Arnoglossus laterna

North Atlantic

2.2

?

1978-2001

Perry et al. (2005)

 

Arctogadus glacialis

Arctic

?

?

?

Lovejoy (2008)

 

Cymatogaster aggregata

Alaska USA

55.6

389

1998-2005

Wing (2006)

 

Echiichthys vipera

North Atlantic

2.2

?

1978-2002

Perry et al. (2005)

 

Entelurus aequoreus

North Atlantic

165

990

1999-2005

Harris et al. (2007)

 

Glyptocephalus cynoglossus

North Atlantic

2.2

?

1978-2003

Perry et al. (2005)

 

Hermosilla azurea

California USA

31.4

440

1981-1995

Sturm & Horn (2001)

 

Micromesistius poutassou

North Atlantic

2.2

?

1978-2004

Perry et al. (2005)

 

Oncorhynchus gorbusha

Bering Sea

?

?

?

Grebmeier et al. (2006)

 

Sparisoma cretense

Italy

?

220

? - 2000

Guidetti & Boero (2001)

 

Thalassoma pavo

Mediterranean Sea

66

990

1980-1995

Bianchi (2007)

 

Trisopterus esmarkii

North Atlantic

2.2

?

1978-2005

Perry et al. (2005)

 

Trisopterus luscus

North Atlantic

2.2

?

1978-2006

Perry et al. (2005)

 

Zenopis conchifer

England

6

990

1960-1995

Stebbing et al. (2002

Mammals

Eschrichtius robustus

Bering Sea

?

?

?

Grebmeier et al. (2006)

 

Odebenus rosmarus

Bering Sea

?

?

?

Grebmeier et al. (2006)

 

Ursus maritimus

Arctic

?

?

?

Lovejoy (2008)

As seen in Table 1 species surveyed cover a vast area (Appendix 1) from the Arctic to Antarctica and Australia and have varying rates of shift, from l65 km per year for the Snake pipefish (Entelurus aequoreus ) to 2.2km/year for North Sea fishes.

Birds

Out of the 10 bird species noted to have changed range position, the rate of range shift has only be accountable for three species. These are the ring-billed gull (Larus delawarenis), Hartlaub's gull or king gull (Larus hartlaubii) and the crowned cormorant (Phalacrocorax coronatus). These species are located in both hemispheres (ring-billed gull in the northern and king gull and crowned cormorant in the southern) and have significantly different rates of range shift (the difference in rates being 38.4km per annum).

The ring-billed gull, located in Canada, shifted range by 275km between 1965 and 2002, a rate of 7.4km per year, whereas the king gull and crowned cormorant (both found in South Africa) moved range by 550km and 355km respectively between the early 1990's and 2003 - a rate of 45.8km/year and 29.6km per year. Overall, observed bird species have moved an average distance of 393km at the rate of 27.6km per year although measurements of many more species over a longer time would be needed to confirm this fully.

Fishes

Fourteen fish species were monitored globally to show changes in range, ten of these have shown a calculable rate of change per year. These species were all found in the northern hemisphere, with the majority (seven species) found in the North Atlantic, average distance for fish movements is 759.8km at the rate of 30.7km per year. North Atlantic species (Scalfish, lesser weever, witch flounder, blue whiting, Norway pout and bib) have comparatively low rates of range shift (2.2km/year) with the exception of snake pipefish (165km/year) (See Appendix 3 for Latin translation).

Species located outside of the Atlantic have been seen to be moving at a fast rate, for instance the shiner perch in Alaska has moved 389km in seven years; a rate of 55.6km per year - much faster than the North Atlantic species. The difference in the rate of range shift between fish species is 162.8km per year, meaning species are moving at considerably different rates, although, more species would have to be monitored for longer to make a full account of changes.

Comparison between Birds and Fishes Would this go in the discussion??

Due to a lack of data for both taxonomic groups no definitive conclusions can be made, however by using data presented here it can be seen that fishes are moving at faster rate than birds. The average rate of bird range shifts is 27.6km per year whereas for fishes the rate is 30.7km per year; where birds moved an average of 393km and fishes 759.8km, both over an average time period of 20 years. These measurements show that fish species are responding faster to climate change than bird species.

These rates were taken from 3 bird species and 10 fish species monitored over a variety of time periods, even though they cover the same average time. The ring-billed gull had been monitored for 37 years - much longer than the other bird species that were monitored for 12 years, whereas fish species were monitored for much wider time range. Snake pipefish in the North Atlantic were monitored for six years, zebra perch in California for 14 years and the bib in the North Atlantic has been monitored for 28 years. This difference in time period may have an effect on the observed range change rate as the more data that is collected the more accurate the shifts will be and so to fully state a range shift average for both birds and fishes more data must be collected.

http://www.gebco.net/data_and_products/gebco_world_map/images/gda_world_map_large.jpg < world map reference!!(Grebmeier et al., 2006)

Response of Invertebrates

FIG. 4. Northwest Atlantic time series of salinity, phytoplankton, and zooplankton data from Gulf of Maine/Georges Bank

Region. Dashed lines indicate mean values during the decades 1980-1989 and 1990-1999; shaded areas correspond to 95%

confidence intervals. (a) Time series of annual mean (blue) and minimum (red) salinities as determined with data derived from

National Marine Fisheries Service hydrographic surveys. (b) Time series of autumn phytoplankton color index values as

determined with data derived from continuous plankton recorder (CPR) surveys. (c) Time series of annual small copepod

abundance anomaly values as determined with data derived from CPR surveys. (d) Time series of annual abundance anomaly

values for fifth copepodid and sixth adult stages of the large copepod species, Calanus finmarchicus (red), and abundance anomaly

values for earlier copepodid stages (blue) as determined with data derived from CPR surveys (figure modified from Greene and

Pershing [2007]). Greene et al 2008

Put in world map to show locations and table of species

I expect to see one main figure that shows the spread rates of both groups in a box plot or something like it.

.

Comparison of invertebrates and vertebrates

Put in box plots to compare the shifts of both.

Discussion

Describe findings and interpret - answer hypothesis by comparing both verts and inverts together.

Main section

Make solid arguments

Relate findings and interpretations to the literature

Less info for verts than inverts!!

Conclusion

Summarise main points

Final judgement

Predict counter arguments

Any further study needed

Integrate results into real life

Appendices

Not included in word count

Can include anything that wouldn't fit into main body

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