DIATOMS AS A FOOD SOURCE FOR SORITES DOMINICENSIS
by
Tiffany Gaston
A Thesis Submitted to the Faculty of
The Wilkes Honors College
in Partial Fulfillment of the Requirements for the Degree of
Bachelor of Arts in Liberal Arts and Sciences
with a Concentration in Marine Biology
Wilkes Honors College of
Florida Atlantic University
Jupiter, Florida
May 2008
DIATOMS AS A FOOD SOURCE FOR SORITES DOMINICENSIS by Tiffany Gaston
This thesis was prepared under the direction of the candidate’s thesis advisor, Dr. Susan Richardson, and has been approved by the members of her supervisory committee. It was submitted to the faculty of The Honors College and was accepted in partial fulfillment of the requirements for the degree of Bachelor of Arts in Liberal Arts and Sciences.
SUPERVISORY COMMITTEE:
______Dr. Susan Richardson
______Dr. Jon Moore
______Dean, Wilkes Honors College
______Date
ii Acknowledgments
First of all, I would like to thank Dr. Susan Richardson for her guidance in the
field and in the laboratory. I am very grateful for her direction and support throughout the
thesis writing process. In particular, I would like to thank Dr. Paul Hargraves for his help identifying SEM and LM images of diatoms and Dr. Evelyn Gaiser for the protocols necessary for diatom mounting. I would also like to thank Dr. Jon Moore for encouraging me to work with Dr. Richardson, for being my second reader, and for supplying the digital camera. I would like to thank Dr. Quintyne as well for permitting me to use the inverted scope. Special thanks to the Smithsonian team at Ft. Pierce for the use of the lab and the technical assistance of the scanning electron microscope. An additional thanks to
Dr. Smith for allowing me to borrow the chemicals necessary for mounting, and to Dr.
Kundalkar for helping me prepare the Naphrax. Thank you also to Ms. April Mistrik for allowing me to use the hood afterhours. Lastly, I would like to thank Chris Harris,
Tatiana Mendoza, and Dr. Wetterer for editing my thesis.
iii ABSTRACT
Author: Tiffany Gaston
Title: Diatoms as a food source for Sorites dominicensis
Institution: Wilkes Honors College of Florida Atlantic University
Thesis Advisor: Dr. Susan L. Richardson
Degree: Bachelor of Arts in Liberal Arts and Sciences
Concentration: Marine Biology
Year: 2008
Sorites dominicensis is a common Foraminifera living on Thalassia testudinum
seagrass blades in the Indian River Lagoon. This locality is unique because epiphytic
diatoms, characteristic of Caribbean and temperate environments, are expected to make
up the biofilm community. Diatoms compose a large part of the Foraminiferan diet. It is important to understand the cause and effect relationship of population variation between
S. dominicensis and its preferred food source, since both are valuable bioindicators. We examined the selective feeding of S. dominicensis by first, identifying the diatom assemblage. Second, we utilized scanning electron microscopy (SEM) in order to identifying the remains of diatoms entrapped in pseudopodial nets and in debris piles. We found that Mastogloia and Cocconeis were the most prominent genera in the overall diatom assemblage. The food preference of S. dominicensis included Amphora, Berkeleya rutilans,Cocconeis, Licmophora dalmatica, Mastogloia, Odontella rhombus,
Plagiogramma pulchellum var. pygmaeum, and Skeletonema.
iv Table of Contents
List of Figures…………………………………………………………………………….vi
List of Tables…………………………………………………………………………….vii
Introduction………………………………………………………………………………..1
Methods……………………………………………………………………………………3
Results……………………………………………………………………………………..6
Discussion……………………………………………………………………………..…11
References………………………………………………………………………………..14
Appendix…………………………………………………………………………………16
v List of Figures
Figure 1. Diatom assemblage abundance, excluding the “Very Rare” taxa………………7
Figure 2. Light microscopy images of the most common diatoms attached to T. testudinum at the Indian River Lagoon study site...... 8
Figure 3. Scanning Electron Microscopy Images of Diatoms in the vicinity of S. dominicensis……………………………………………………………………..9
vi List of Tables
Table 1. Diatom Diversity/ Abundance at the Study Site…..……………………………..7
vii Introduction
Sorites dominicensis is a symbiont-bearing foraminiferan confined to shallow tropical and subtropical reef habitats (Hallock 1999). Zooxanthellae, the algal symbionts sequestered by S. dominicensis, enhance the calcification of the shell (test) and serve to supplement the host’s diet with the products of photosynthesis. However, S. dominicensis obtains most of its nutrients by feeding upon nanoplankton, bacteria, and diatoms less than 50 µm in size (Hallock 1999; Lipps and Valentine 1970). A large component of the diet of S. dominicensis is epiphytic diatoms of unknown taxa.
Diatoms are unicellular algae found in the benthos, as phytoplankton, or attached to substrata in marine and fresh water habitats. Epiphytic diatoms living on the surface of seagrasses, make up the basal community. They are pioneers that lay the foundation for coralline red algae, bryozoans, hydrozoans, and other epiphytic biota that reinforce the seagrass blades (Borowitzka et al. 2006). T. testudinum is an excellent phytal substrate for diatoms as well as foraminifera due to its lack of toxins and greater surface area for attachment (Richardson 2001). The microbial biofilm community attracts grazers to forage on seagrass meadows. In turn, this elicits larger predators and perpetuates the food web (Admiral 1984).
In addition to being vital to the food web, marine diatoms are recognized among the scientific community as valuable bioindicators because they are diverse and respond rapidly to environmental change (Bianchi et al. 2003). Variation in the expected diatom assemblage, which is obtained from baseline studies, may indicate a stressed environment. For example, an increase in pollution tolerant marine subtropical diatom species such as Achnanthes brevipes var. intermedia, Amphora coffaeformis, Epithemia
1 adnata var. porcellus, and Nitzschia elegantul, in an otherwise healthy environment, may
denote a stressor, possibly more than average levels of nutrients (Della Bella et al. 2007).
Waters near developed coastal areas are at the greatest risk of eutrophication.
Epiphytic foraminiferans and diatoms adhere to the surface of T. testudinum, a seagrass
that grows in nearshore habitats and is frequently subject to eutrophication and/or thermal
stressors. Therefore, biomonitoring of S. dominicensis and diatom populations may serve as water quality indicators (Richardson 2006). For example, the presence of S. dominicensis is indicative of healthy, marine conditions, and would be less prevalent at eutrophic sites (Carnahan 2005). Carnahan (2005) found that the abundance of S. dominicensis in Biscayne Bay, renowned for increasingly polluted waters, declined as populations of stress-tolerant foraminifera species such as Ammonia, Cribroelphidium,
Nonion, and Haynesina proliferated.
Since S. dominicensis and marine epiphytic diatoms are important as bioindicators and are integral components of the food web, it is essential that we understand the impacts they have on each other. Scientific literature is deficient concerning S. dominicensis; even less is published about its food selection. A single study, conducted by Lee and Bock (1976), remains the only source of information specific to S. dominicensis and food selectivity. The study found that S. dominicensis does exhibit a food preference when experimentally given food options. It is necessary to build upon their findings so as to discover the food preference of S. dominicensis, which is critical in understanding population variation.
In this study, we examined the diet of Sorites dominicensis in its natural
environment, attached to T. testudinum in the Indian River Lagoon (IRL). The IRL, a
2 diverse estuary, stretching about 193 – 250 km, can vary by 30ºC in water temperature
(Hargraves 2002). Fauna in the northern portion of the estuary is more characteristic of a temperate climate, while the biota in the southern half is typical of the tropical and subtropical zones (Hargraves 2002). Since the Indian River Lagoon is in a biogeographic transition zone, we found it important to our study to determine how much of an influence the northern more temperate waters had on the diatom assemblage at our study site.
The first half of the study was focused on determining the diatom assemblage and the relative abundance of diatoms at the site using light microscopy. Second, analysis of
SEM images made it possible to examine S. dominicensis while feeding. We considered the projection of pseudopodia surrounding and adjacent to diatoms as a food selection. In addition, discarded diatom frustules found adjacent to S. dominicensis were also considered a dietary preference.
Methods
Diatom Assemblage
In March 2008, during high tide we collected twenty short shoots of T. testudinum from a study site in the intracoastal waterway in Jupiter Sound, across from the lighthouse (26.957ºN, 80.078ºW). We scraped off the biofilm community on the surface of each seagrass blade and placed it in a beaker (average surface area of one seagrass
2 blade was 21.86 cm ). To begin the process of oxidation, we added sulfuric acid (H2SO4) to the sample in a ratio of 2:1. H2SO4 dissolved the organic matter so that the diatom assemblage, made of silica, was remaining. Next, we added an aqueous solution of
3 potassium permanganate (KMnO4), a strong oxidizing agent, until the sample became a
deep brown color and stopped bubbling. We then added oxalic acid to the sample until a color change occurred and the sample became clear. After the oxidation process was completed, we added distilled water and let the sample sit overnight. After the diatoms settled out of the solution, we decanted the sample to a volume that did not agitate the settled diatoms and refilled it with distilled water. Each round of dilution required the sample to settle for at least 6 hours. Once the final dilution was complete and the sample was no longer acidic (i.e. it had reached a pH of 6.98), we began the slide preparation.
The aqueous portion of the solution was removed until ~50 ml remained, which we poured into a 50 ml tube and rinsed the residue with distilled water. We allowed the solution to settle for 6 hours and then decanted it to ~5 ml. We removed the 5 ml of sample by pipette and placed it into a labeled glass vial. The residue left behind on the
tube was rinsed with 1 ml of distilled water and incorporated into the glass vial. We
removed ~100 µl of the homogenized sample via pipette and placed it on a glass slide
which was then dried on a hot plate. We inverted a coverslip containing about three drops
of Naphrax, a high refractive index diatom mountant, onto the dried slide. We heated the
slide and coverslip to greater than 300 ºF, until the bubbling stopped. We pressed the
coverslip to the slide until the Naphrax hardened, then we removed the excess Naphrax
and rinsed the slide with ethanol.
We took images of the diatom slides with a Nikon Coolpix 950 digital camera
mounted to an ocular of a compound light microscope. In order to indentify species, we
examined intricacies in the siliceous frustules of diatoms, as well as shape, size, and color
differentiation. Diatoms in the genus Mastogloia were difficult to tell apart based on
4 surface characteristics and therefore were distinguished by analysis of the internal
anatomy. Identifications of Mastogloia species were made using light microscopy in an
attempt to look at the number and positioning of loculi attached to the intercalary band
(Stephens and Gibson 1980). In addition to identifying diatoms using LM images, we
utilized detailed physical descriptions from the scientific literature such as Cleve (1965),
Round et al. (1990), and Stephens and Gibson (1979), (1980) in order to make accurate
identifications. Dr. Paul Hargraves, an experienced diatomist, was an additional source
for species identifications. We calculated abundance estimates using four fields of view
on each of the four LM slides.
Diet of Sorites dominicensis
Short shoots of T. testudinum were randomly collected from the study site on
April 2008, at low tide. We located live specimens of S. dominicensis attached to
seagrass blades and cut out a periphery of ~2 mm. We transferred the specimens to
calcium free saltwater for 1.5 hours in order to preserve the pseudopodia. We fixed the
specimens in 2% glutaraldehyde and seawater overnight at room temperature. We later
rinsed the specimens with seawater three times and began the postfixation process by
soaking specimens in a 1% osmium tetroxide (OsO4) and seawater solution for an hour.
We again rinsed the specimens in seawater. We used a graded ethanol series of 30, 50,
70, 95, and then 100% ethanol for ~5 minutes in each concentration in order to dehydrate
the specimens. Once the dehydration process was complete, we transferred the specimens
into metal baskets and critical point dried them in a Samdri-790 Critical Point Drier which utilizes liquid carbon dioxide. We mounted the dried specimens on stubs and coated them with a gold/palladium alloy. The preceding SEM protocols allow for high
5 quality surface images which aid in the identification of diatoms preserved within the
pseudopodia or in the discard pile.
Results
Diatom Assemblage
The diatom assemblage of the site showed a diverse community of marine
diatoms (Table 1). Mastogloia was the most prominent genus, making up ~62.5% of the
total diatom assemblage. M. angulata was the single most abundant species, which represents over a quarter of the Mastogloia genus. The second most abundant Mastogloia
species was M. grunowi and it comprised 18% of the genus (Figure 1). Another important
genus, comprised of Cocconeis sp. 1 & 2, makes up 17.5% of the diatom assemblage at
the study site. This genus is less diverse than Mastogloia and was represented less in the
overall diatom assemblage. Even though there is an obvious diversity at the site, there are
a few taxa that dominate the assemblage, they are: Cocconeis sp.1 & 2, Mastogloia
angulata, Mastogloia grunowii, and Mastogloia sp. 7, 8, 9 & 10 (Figure 2).
6 Table 1: Diatom Diversity/ Abundance at the Study Site ______Actinoptychus senarius VR Mastogloia sp. 5 VR Actinoptychus sp.1 VR Mastogloia sp. 6 VR Amphora sp. 1 VR Mastogloia sp. 7 & 8 VC Biddulphia sp.1 (Odontella sp.) R Mastogloia sp. 9 VC Cocconeis sp.1 & 2 VC Mastogloia sp. 10 VC Cyclotella sp.1 R Mastogloia sp. 11 R Cymatosira lorenziana VR Navicula sp. 1 VR Diploneis sp.1 VR Navicula sp. 2 VR Glyphodesmis sp. 1 VR Nitzschia sp. 1 VR Gyrosigma or Pleurosigma sp.1 VR Nitzschia sp. 2 VR Mastogloia angulata VC Plagoigramma pulchellum VR Mastogloia binotata C Rhopalodia sp. 1 C Mastogloia cribrosa VR Synedra hennedyana VR Mastogloia fimbriata VR Synedra sp. 1 VR Mastogloia grunowii VC Synedra sp. 2 VR Mastogloia manokwariensis VR Thalassiosira sp. 1 VR Mastogloia sp. 1 VR Coscinodiscus sp. R Mastogloia sp. 2 VR Triceratium sp .1 VR Mastogloia sp. 3 VR Triceratium sp. 2 VR Mastogloia sp. 4 VR Triceratium sp. 3 VR ______VC- Very Common (6.25-17.5% of the diatom assemblage), C-Common (3.75-6.25%), R-Rare (1.25- 3.75%), VR- Very Rare (≤ 1.25%)
Cocconeis sp. 1 & 2 Cyclotella sp. 1 Mastogloia angulata M. binotata
M. grunowii Mastogloia sp.7& 8
Mastogloia sp. 9 Mastogloia sp. 10 Mastogloia sp. 11 Rhopalodia sp. 1
Figure 1: Diatom assemblage abundance, excluding the “Very Rare” taxa
7 1 2 3 4 4
5 6 7 8
Figure 2: Light microscopy images of the most common diatoms attached to T. testudinum at the Indian River Lagoon study site. 1) Cocconeis sp. 1 2) Cocconeis sp.2 3) Mastogloia angulata 4) M. grunowii 5) Mastogloia sp. 7 6) Mastogloia sp. 8 7) Mastogloia sp. 9 8) Mastogloia sp. 10
Diet of Sorites dominicensis
The following diatom taxa represent the preferred food source of S. dominicensis exclusive to the locality: Amphora, Berkeleya rutilans,Cocconeis, Licmophora dalmatica, Mastogloia, Odontella rhombus, Plagiogramma pulchellum var. pygmaeum,
Skeletonema, and one unidentified species (Figure 3). Various taxa identified by SEM were not noted in the overall diatom assemblage, they were: Berkeleya rutilans.
Licmophora dalmatica, Odontella rhombus, and Skeletonema sp.
8 Figure 3: Scanning Electron Microscopy Images of Diatoms in the vicinity of S. dominicensis
Amphora sp. Amphora sp.
Berkeleya rutilans Cocconeis sp.
Cocconeis sp. Cocconeis sp.
9
Central diatom is Cocconeis sp. Licmophora dalmatica Right most diatom is Odontella rhombus
Mastogloia sp. Plagiogramma pulchellum var. pygmaeum
Skeletonema sp Unidentified
10 Discussion
Diatom Assemblage
By comparing the taxa list from our study to those conducted in various climates,
we aim to determine what extent cooler waters influence the diatom assemblage at our
unique locality.
A benthic diatom study off the coast of North Carolina, serves as our reference for
temperate biota. The overwhelming abundance of the genera Amphora, Cocconeis,
Diploneis, and Navicula, as well as the presence of the genera Fragillaria, and the
absence of Cyclotella, are characteristic patterns of Carolinian taxa (Cahoon and Laws
1993). Therefore it can be concluded that the high incidence of Mastogloia species over
Cocconies, the occurrence of Cylcotella, and the underrepresentation of Amphora,
Diploneis, and Navicula species at our site, distinguish it from the temperate climate.
Studies conducted in the Florida Keys on tropical diatom distributions found an
abundance of Mastogloia epiphytic to T. testudinum (Frankovich et al. 2006). An earlier
study in the same location by Montgomery (1978) yielded Mastogloia abundance as high
as 70.7%, similar to our estimate of 62.5%. Corlett and Jones (2007) identified epiphytic
diatoms in the British West Indies, associated with Caribbean (tropical) fauna.
Mastogloia dominated the diatom assemblage while Cocconeis was also very common.
These findings are consistent with our LM results in which both Mastogloia and
Cocconeis were very common. In addition, comparison of the diatom species list from the Caribbean studies and our own, resulted in nearly identical taxon. For that reason, the
diatom assemblage at our study site exemplifies the influence of Tropical, Caribbean taxa in the southern portion of the IRL. The slight discrepancy in the tropical taxa compared to
11 our own is possibly due to the impact of somewhat cooler, subtropical water from the
IRL on the diatom assemblage.
A diverse community of diatoms and the presence of a healthy population of
Sorites dominicensis, indicates that healthy marine conditions prevail at the study site
(Carnahan 2005). If there was a salinity change, hot water influx, or eutrophication from
a point source, the diatom community would respond (Frankovich et al. 2006; Sundback
& Snoeijs 1991). If our study site became stressed, the diatom assemblage would
deteriorate and prolific species would take over, thereby causing a fluctuation of the
originally stable food source. Therefore, a preliminary study of the diatom assemblage at
this increasingly recreational site, was crucial in understanding patterns and the cause and
affect relationship between S. dominicensis and epiphytic marine diatoms.
This research serves as a baseline for future studies. With increasing human
populations along the coast, it is our responsibility to understand our impact on the
environment. Alteration of the diatom assemblage and/or decline in the abundance of S.
dominicensis in developing coastal areas, may serve as an indicator of environmental
change. A more thorough examination of the fluctuation in diatom populations
throughout the year would be necessary in order to incorporate seasonal variation and establish a complete and sufficient baseline for comparison.
Diet of Sorites dominicensis
One likely explanation for the discrepancy in the SEM results compared to the
overall diatom assemblage may be that the species were very rare in the overall diatom
assemblage and thus were not represented in the taxa list. Therefore, S. dominicensis is
consuming what is not readily available. Mastogloia species were more diverse and
12 abundant at the study site, however Cocconeis species were found more frequently
fractured in the vicinity of the foram test. Even though the most common diatoms in the
area were elliptical, the foraminiferan is consuming a variety of shapes. Additionally, the
diatom assemblage was largely composed of epiphytic diatoms, while the food source is
benthic, planktonic, and epiphytic in origin. These discrepancies may further substantiate
Lee and Bock’s conclusion, that S. dominicensis exhibits a food preference. It is plausible
that the selectivity may be based on the size of the diatom. S. dominicensis may be choosing smaller diatoms, which seems a reasonable explanation for why lengthy rod shaped diatoms in the genus Synedra or large centric diatoms such as Coscinodiscus species were not present in the SEM results.
A study aimed at further distinguishing species of the diatoms in the SEM results would be helpful in advancing our understanding of population variation in formainiferans and diatoms at this tropical locality. If Cocconeis, the preferred food source of S. dominicensis, declines at our study site over the span of a couple years, will populations of S. dominicensis consequently plummet? This pilot study comes closer to answering this question, but further research is needed in order to fully understand the patterns associated with Sorites dominicensis and its preferred food source.
13 References
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Bianchi, F., F. Acri, F. Bernardi Aubry, A. Berton, A. Boldrin, E. Camatti, D. Cassin and A. Comaschi. 2003. Can plankton communities be considered as bio-indicators of water quality in the Lagoon of Venice? Marine Pollution Bulletin 46(8): 964-971.
Borowitzka, M., P. Lavery and M. Keulen. 2006. Epiphytes of seagrasses. In: Larkum, A.W.D., Orth R.J., Duarte C.M., editors. Seagrasses: Biology Ecology and Conservation. The Netherlands (Dordrecht): Springer Press. p 450.
Cahoon, L. B. and R.A. Laws. (1993) Benthic diatoms from the North Carolina continental shelf: Inner and mid shelf. Journal of Phycology 29, 257–263.
Carnahan, E. 2005. Foraminiferal assemblages as bioindicators of potentially toxic elements in Biscayne Bay, Florida. [Ph.D. dissertation]. Tampla (FL):University of South Florida. p. 1-20.
Cleve, P.T. 1965. Synopsis of the Naviculoid Diatoms. A. Asher & Co., Amsterdam.
Corlett, H. and B. Jones. 2007. Epiphyte communities on Thalassia testudinum from Grand Cayman, British West Indies: Their composition, structure, and contribution to lagoonal sediments. Sedimentary Geology 194 (3-4): 245-262.
Della Bella,V., C. Puccinelli, S. Marcheggiani, and L. Mancini. 2007. Benthic diatom communities and their relationship to water chemistry in wetlands of central Italy. Annales De Limnologie. 43(2): 89-99.
Frankovich, T.A., E.E. Gaiser, J.C. Zieman and A.H. Wachnicka. 2006. Spatial and temporal distributions of epiphytic diatoms growing on Thalassia testudinum Banks ex Konig: relationships to water quality. Hydrobiologia 569: 259-271.
Gibson, R.A., F.C. Stephens, J.T. Paxton, C.G. Howren, and R.S. Johnson. Phytoplankton and hydrochemical variations in the Indian River system including an inventory of pollution sources. In: Young, D.K., editor. Indian River Coastal Zone Study, Second Annual Report (1974-1975). Virginia (Arlington): Compass Publications. p 14-42.
Hallock, P. 1999. Symbiont-bearning Foraminifera. In: Modern Foraminifera. (Sen Gupta, B.K., Ed), Kluwer Academic Publishers, Dordrecht The Netherlands. pp 123-139.
14 Hargraves, P.E. 2002. Diatoms of the Indian River Lagoon, Florida: an annotated account. Florida Scientist 65(2):225-244.
Lee J.J. and W.D. Bock. 1976. The relative importance of feeding in two species of soritid foraminifera with algal symbionts. Bulletin of Marine Science 26: 530- 537.
Lipps, J.H. and J.W. Valentine. 1970. The role of foraminifera in the trophic structure of marine communities. Lethaia 3(3): 279-286.
Montgomery, R. T. 1978. Environmental and ecological studies of the diatom communities associated with the coral reefs of the Florida Keys. [Ph.D. dissertation]. Tallahassee (FL):Florida State University.
Richardson, S.L. 2006. Response of epiphytic foraminiferal communities to natural eutrophication in seagrass habitats off Man O'War Cay, Belize. Marine Ecology 27(4): 404–416. http://www.blackwell-synergy.com/doi/full/10.1111/j.1439- 0485.2006.00096.x?cookieSet=1
______. 2001. Endosymbiont change as a key innovation in the adaptive radiation of Soritida (Foraminifera). Paleobiology 27(2): 272-289.
Round, F.E., R.M. Crawford and D. G. Mann, 1990. The Diatoms Biology and Morphology of the Genera. Cambridge University Press, New York.
Stephens, C. F. and R. A. Gibson. 1980. Ultrastucture studies on some mastogloia species of the group Inaequales (Bacillariophyceae). Journal of Phycology 16: 354-363.
______.1979. Ultrastructural studies on some Mastogloia (Bacillariophyceae) species belonging to the group Ellipticae. Botanica Marina. 22: 499-509.
Sundback, K. and P. Snoeijs, 1991. Effects of nutrient enrichment on microalgal community composition in a coastal shallow-water sediment system: an experimental study.
15 APPENDIX
GENERA: Actinoptychus
Actinoptychus sp.1 A. senarius
GENERA: Amphora
Amphora sp. 1
GENERA: Biddulphia (Odontella)
Biddulphia sp.1
GENERA: Cocconeis
Cocconeis sp. 1 Cocconeis sp. 2
16
GENERA: Cyclotella
Cyclotella sp. 1
GENERA: Cymatosira
C. lorenziana
GENERA: Diploneis
Diploneis sp. 1
GENERA: Glyphodesmis
Glyphodesmis sp. 1
17 GENERA: Gyrosigma or Pleurosigma
sp. 1
GENERA: Mastogloia
M. angulata M. binotata M. cribrosa M. fimbriata
M. grunowi M. manokwariensis M. sp. 1 M. sp. 2 M. sp. 3
M. sp. 4 M. sp. 5 M. sp. 6 M. sp. 7
18
M. sp. 8 M. sp. 9 M. sp. 10 M. sp. 11
GENERA: Navicula
Navicula sp. 1 Navicula sp. 2
GENERA: Nitzschia
Nitzschia sp. 1 Nitzschia sp. 2
19 GENERA: Plagoigramma
Plagoigramma pulchellum
GENERA: Rhopalodia
Rhopalodia sp. 1
GENERA: Synedra
Synedra hennedyana Synedra sp. 1 Synedra sp. 2
GENERA: Thalassiosira
Thalassiosira sp. 1
20
GENERA: Coscinodiscus
Coscinodiscus sp.
GENERA: Triceratium
Triceratium sp .1 Triceratium sp. 2 Triceratium sp. 3
21