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Phytoplankton Data

Zooplankton Data

 At station A salinity 10.1 there was a high frequency of Cryptophytes and Thalassiosira with 150 and 20 respectively these organisms have genera found in freshwater/ brackish water (Salmaso and Tolotti, 2009) which for a salinity of 10.1 PSU means that this sample was collected by Winnie the Pooh and so the type of organisms’ present is to be expected. In addition, Bacillaria was observed albeit in lower frequencies at salinity 10.1 but are a typical genus of dominant genus found in freshwater (Belcher et al 1986).

At the lower salinities so Stations A which were sampled by the Winnie the pooh  with corresponding salinities of 10.1 and 18.4 the most numerous phytoplankton observed were cryophytes and cryptomonads which are part of the  same genus  this genus colonises a variety of habitats including marine and freshwater (Salmaso and Tolotti, 2009)  and therefore cryptomonads were found in all but two of the samples which was Station H  and Station D at 3.6 m however their frequency varies with the highest frequency seen at salinity 10.1 as the salinity increases the frequency of cryptomonads decreases steadily with Station C with a salinity of 31.1 and a frequency of 14 compared with Station I which was the furthest out towards the breakwater which had a frequency of 1.

At the third sample taken at station A with a salinity of 28.3 the most numerous phytoplankton taxa was the Dinoflagellates however the cryptophytes were still noted in addition to some genera of diatoms such as coscinodiscus (Coscinodiscus wailesii Gran & Angst, 1931, WORMS, 2018) and chaetoceros. However, at station B which was the next station from Station A with a salinity of 32.1 we saw a rapid decrease in the cryptophytes and an increase in ciliates becoming the more dominant phytoplankton group, with a frequency of 14, with the two diatom groups beginning to increase in frequency.

At Location C which is located by the Saltash pontoon with a salinity of 31.1 this sample was taken at the surface still had the cryptomonads as the dominant phytoplankton species but there was a large increase in diatom genus’s with Rhizosolenia, Thalassaioria (Thalassiosira pseudonana Hasle & Heimdal, 1970 WORMS,2018; Rhizosolenia setigera Brightwell, 1858 WORMS, 2018) and Chaetoceros. Compared with station C at depth 3.9 cm in which the dominant genus was the dinoflagellates with a frequency of 9 and the cryptomonads had a much lower frequency of 4. This could be explained as dinoflagellates are usually found in marine/ brackish water which is where this sample was taken (Salmaso and Tolotti, 2009) at third sample taken at Station C at depth 0.9 m again the most dominant phytoplankton was the crytomonas with a frequency of 9. The next station D at depth 1.2m salinity 33.3 and depth 3.6m with as salinity of 33.6 the dominant phytoplankton changed to diatoms with a frequency of 15 and cryptophytes a close second with 14 at 1.2m however at 3.6m there were only two phytoplankton genera noted down protoperidinium and pleurosigma with 1 each which is a dinoflagellate and diatom respectively. At salinity 33.2, station E, the dominant phytoplankton observed at 0.67m was again crytomonas with a frequency of 8, compared with station G with a salinity of 33.1 taken at a depth of 1.2m the more dominant species observed was Chaetoceros. At Stations H and I which had the same salinity observed however the two samples were taken at different depths with 8.9m and 1.2m respectively however both dominant phytoplankton were diatoms just different genus’s Leptocylindrus and Chaetoceros (Leptocylindrus danicus Cleve, 1889 WORMS, 2018; Chamnansinp et al, 2015).

 

At station J there were phytoplankton samples taken at different depths at 1.1 m, salinity 34.7the dominant phytoplankton was cryptophytes with a frequency of 7 followed closely by Rhizosolenia and Chaetoceros. However, at the same station J at depth 5.2m, salinity 34.8, the dominant phytoplankton changed the frequency of cryptophytes decreased rapidly to 1 and the most dominant phytoplankton was Diatom Chaetoceros Compressus with a frequency 105 with the second most abundant was Guinardia with a frequency of 35, these are both diatoms, the Chaetoceros genus is one of the most abundant found within phytoplankton (Chamnansinp et al, 2015).


From our data we can observe that the number of Copepods per m-3 increases from the freshwater sample which was Site 1 (Winnie the Pooh) with a salinity of 4.2 PSU, to samples 2 and 3 with a salinity of 21.3 and 30.8. These samples respectively increased from 95.2m-3 to 1459.1 m-3 and then to 17973m-3 at Sample 3, site 18. There is a marked contrast in Copepods in those measured by the Falcon Spirit with 344m-3 Copepods measured at Site C, which was close in distance to the sample taken at Site 18. We see an increase at Site H to 920.9 m-3 before decreasing to a low of 229.18m-3 at Site I.

The number per m3 of fish larvae decreases from 31.7 m-3 at Site 1 to 25.2 m-3 at site 10 sample 2. We then begin to see an increase at site 18 sample 3 in which there were 27 m-3. At Site C, which is located close to Site 18, there was vastly different fish larvae frequency with 9 m-3, there were no fish larvae observed at Site I. However, at Site H there was a very high abundance of fish larvae with 273.1 m-3 recorded. At site 1 Sample 1 the observed fauna was: Copepods, Copepod Naupilli, Cladocera, Mysticea and fish larvae. The second sample for the Winnie the pooh again noticed Copepoda, fish larvae and Mysidacea but Polychaeta larvae were additionally observed. In sample 3 Copepods, Copepod Naupilli, Mysidacea and fish larvae were observed but in addition Gastropod larvae and Appendicularia were observed with 27 and 27 m-3 respectively. These Appeniducularians are a tunicate common in most types of marine environment (Appendicularia University of Tasmania,2018).  At Site C copepods were observed still and the Copepod Naupilli however, no Mysidacea were observed but instead there was a large increase in the Polychaete larvae (19 m-3) the Gastropod larvae (247 m-3) and fish larvae (9 m-3).

Site H appears to follow an alternative trend with Copepods and Copepod Naupilli present but also Cladocera were observed again. The Polychaeta larvae and the fish larvae were observed, as noted earlier the fish larvae were in high abundances. Hydromedusae were observed at Station H which were not observed at any other site in the sampling transects. This site H contrasts with site I, although they are similar to one another in terms of distance they have completely different zooplankton observed. There was observed, an occurrence of Cirripedia larvae and a much lower frequency per m3 of Copepods seen at Site I however, a higher number of Copepod Naupilli (64.56 m-3) and Cladocera (9.68 m-3) compared with Site H with 28.2 m-3 and 9.4m-3 respectively.

Station H is located near Cremyll; this is at a junction at which you have the River Tamar entering the Narrows. To the side is St Johns lake, this is a protected area with tidal flats, it is illegal to fish in these areas which might explain why we see such high abundances of fish larvae located in the water (Plymouth waterways, 2018). In station I, we saw Cirripedia (barnacle) larvae, this may be because barnacles need to live in a saltwater environment. Additionally, at the East of the Breakwater the right water currents and turbidity needed for the barnacle larvae to survive may be apparent. The Copepoda are known to be one of the most abundant zooplankton seen in the aquatic environment and can be found in a range of habitats from fresh to marine waters. This may explain why there were a high frequency of copepods noted per m3 across the salinity transect (Walter and Boxshall, 2018). The Hydromedusae observed at Site I is typical of what we would expect in British Waters, as there are very few documented freshwater species. Therefore, we would expect to find jellyfish in marine waters which is the salinity of site I.


The zooplankton graph shows the number of zooplankton per m3, across a range of salinities,(0, 4.2, 21.3, 30.8, 32.9, 34.57, 34.6)


The phytoplankton count shows the number of phytoplankton counted in 100 squares, across a range of salinities (0 ,10.1, 18.4, 28.3, 31.1, 32.1, 32.3, 32.9, 33.1, 33.2, 33.3, 33.6, 34.5, 34.7, 34.8)