The need for a protocol of how to study living foraminifera from rocky environments: the case of the Israeli Mediterranean coast
Ahuva Almogi-Labin, Geological Survey of Israel
(Based on the MSc thesis of Limor Gruber, Shahar Lazar, Ruthie Arieli and my own field work)
1. Hard bottoms are common along the Israeli coast (Fig. 1a) They include
the unique intertidal vermetid platforms (Figs. 1b-c), beach rocks and
submarine aeolianite ridges that run parallel to the coast (Figs. 1d-e) down to
several tens of meters. Benthic foraminifera occur frequently in these
environments unlike the nearby sandy habitats that are notably more
impoverished in foraminifera (Hyams-Kaphzan et al., 2008).
Central Israeli coast
1a
Northern Israeli coast
Vermetid platforms
Rocky habitats may be affected by anthropogenic / natural changes. Using
foraminifera to monitor their state of health can encounter difficulties if using
traditional sampling procedures that were developed for soft sediments. The
main difficulties are connected to the question of where, what and how to
sample these habitats, how to treat samples in the laboratory and how to
normalize the analyzed samples.
1b
1c
Submerged aeolian ridge, 10 m,
note, Amphistegina growing on macroalgae
and the hard bottom
Submerged aeolian ridge, rich
in rhodolites and Jania, 12 m
Developing better methodologies for sampling and analyzing foraminifera of
rocky habitats will open an opportunity to study the most widespread rocky
environment on earth - the low latitude coral reefs in a completely different
way than was done so far.
1a. Map showing the distribution of the vermetid platforms
1d
(in blue) along the central Israeli coast, in sections 6-8
1e
2. Foraminifera preference of macroalgae: where, what and how to sample
Looking for Jania
Ulva
Jania
2a.
Hard bottoms are densely populated by
diverse macroalgae. It was found that on
vermetid platforms and nearby subtidal rocks
foraminifera preferentially live on the coralline
algae Jania rubens and the brown algae
Cystosira. Ulva is free of foraminifera.
Northern Israeli coast - vermetid platform
Northern Israeli coast – submerged aeolian ridge
Haifa Bay, submerged aeolian ridge, 10 m depth
2b.
During the sampling, containers are
2c. Jania is sampled for the living foraminifera.
2d. Amphistegina and Heterostegina were collected
directly placed on Jania, to avoid loss of
foraminifera (especially of the free living forms,
sensu Kitazato (1988). Jania was removed from
the rock, using a flat knife and stained with
Rose Bengal solution.
The underlying sediments are sampled for the
dead foraminifera (e.g. Lazar et al., 2005). On
intertidal platforms dead foraminifera are scarcely
preserved due to the local wave regime that
remove all tests.
from turf growing on attached Spondylus (e.g. Herut
et al., 2005). The shells were removed by a flat knife
and placed into plastic bags.
3. Tel Shiqmona as a case study
Haifa Bay
Study area is marked by the red circle
Spring growth of Cystoseira
3c.
Intensive growth of Jania on Cystoseira in
summer
Small “colonies”, ~10 cm long, of the intergrowing Cystoseira and Jania were
collected from an area of 30/30cm using a metal frame. The macroalgae were covered by
1 L plastic container and the aerial coverage of the algae within the frame was estimated
(for assessing the local carbonate production).
3a. The seaonal population dynamics of
the alien
species Amphistegina lobifera was studied in the
rocky area off Tel Shiqmona, which is densely
covered by macroalgae (Gruber et al., 2005).
3b. Sampling was carried out by scuba diving at
~1.5 m water depth, every 3-5 weeks, from 8/2003 to
9/2004, in triplicate samples.
4. What are the difficulties in treating samples in the
laboratory
• The attached foraminifera are the most difficult to be removed
during the washing procedure. Zohary et al (1980) used double
washing/drying procedure to separate the attached Amphisorus from
the seagrass Halophila.
• In a recent study by Arieli et al. (2011) on foraminifera living on beach
rocks all the macroalgae were tediously screened for the attached
forms.
• Gruber et al. (2005) studied the algal complex of Cystoseira and
Jania (see above no. 3) normalized her numbers per g dry total
weight of the algae, sand grains trapped within, and “others” (i.e.
all the organisms that were attached to the algae). The dry algal
weight comprise about a 1/6 of wet algal weight.
• Another option that needs to be considered is to determine the
surface area of the “spongy” Jania. This parameter is apparently
dictating the numbers of foraminifera that live on this most
abundant species on the Israeli vermetid platforms (see photo–
does any one have any idea of how to calculate surface area?
• Another side-effect of the washing procedure is that many attached
forms are broken mainly at their aperture. This might hinder full
identification of some miliolid species.
5. Normalizing the numerical abundance
• Arieli et al (2011) who studied beach rock sediments that were mixed
with filamentous algae - normalized their abundance per g dry weight
of the two components.
The samples were weighed wet, washed through 150 mm sieve and freeze-dried. Living
specimens, recognized by the presence of chloroplasts, were identified, counted and
weighed. The abundance of the entire foraminiferal population was normalized against
the total dry weight of the algae and the sediment that was trapped within the algae.
Jania rubens
• A different scenario occurs while trying to
normalize the abundance per unit in the case
of foraminifera associated with turf that grow
on rocks, bioherms or coral reefs. Hallock
(personal communication) who studied larger
symbiont-bearing foraminifera in coral reefs
normalized their abundance per estimate of
the collected surface area. No description was
given of what happen when the surface is
irregular.
So far most of the attention in studying hard bottoms was given
to larger symbiont-bearing foraminifera that are associated with
coral reefs. Little attention was given to the full foraminiferal
associations of the coral reefs. Improving the methodologies
used for sampling and processing foraminifera in these
environments will enable us to improve our understanding of
these widespread habitats known to be one of the main
carbonate producers in shallow water
References:
Arieli, R.N., Almogi-Labin, A., Abramovich, S. and Herut, B., 2011. The effect of thermal pollution on benthic
foraminiferal assemblages in the Mediterranean shoreface adjacent to Hadera power plant (Israel). Marine Pollution
Bulletin, 62: 1002-1012.
Gruber, L., Almogi-Labin, A., Sivan, D. and Herut, B., 2005. Life cycle of two symbiont-bearing larger foraminifera –
new arrivers on the Israeli shelf, SE Mediterranean Sea. Workshop on unicellular symbionts, 12-13 December 2005,
Vienna, Austria. http://homepage.univie.ac.at/maria.holzmann/papers/Ahuva_Almogi-Labin.pdf
Herut, B., Halicz, L., Hyams, O. and Almogi-Labin, A., 2005. Tracking dissolved trace metals in Haifa Bay, using benthic
foraminifera. Geological Survey Report GSI / 02 / 2005, 28 pp. (in Hebrew).
Hyams-Kaphzan, O., Almogi-Labin , A., Sivan, D. and Benjamini, C., 2008. Benthic foraminifera assemblage change
along the southeastern Mediterranean inner shelf due to fall-off of Nile-derived siliciclastics. Neues Jahrbuch für
Geologie und Palaeontologie Abhandlungen, 248: 315-344..
Kitazato, H., 1988. Ecology of benthic foraminifera in the tidal zone of a rocky shore. Revue de Paleobiologie 2: 815 –
825.
Lazar S., Almogi-Labin A.‚ Buchbinder B. and Benjamini C., 2005. A sedimentological, faunal and floral profile of the
carbonate system off Akhziv, northern Israel. 5th Regional Symposium of the International Fossil Algae Association, 3031 August 2005, Ferrara, Italy.
Zohary, T., Reiss, Z. and Hottinger, L., 1980. Population dynamics of Amphisorus hemprichii (Foraminifera) in the Gulf
of Eilat (Aqaba), Red Sea. Eclogae Geol.Helv., 73: 1071 - 1049.