VERTICAL ZONATION

AND COMPOSITION

OF

MEIOFAUNA RP2 OF THE

ZSCMST POND

CHAPTER 1 INTRODUCTION

I. Background of the study:

Meiofauna are the tiny invertebrates living within the sediment of the sea. The term meiofauna is derived from the Greek word “meio” meaning smaller{Funch, 2002}.The size of meiofauna ranges between 50 and 500 microns as compared to the size of macro or large fauna.

 

Meiofauna can be found in a wide diversity of habitats. They can occur in both freshwater and marine habitats, from high on the beach to the deep sea. Meiofauna is found in sediments of all kinds from the softest of muds to the coarsest gravels, and all those sediments in between. Meiofauna also can occupy several above sediment habitats like rooted vegetation, moss, macoalgae fronds, seaice and various animal structures {coral crevices, worm tubes, echinoderm spines} {Funch 2002}

Benthic meiofauna are important components of coastal and estuarine ecosystems. As grazers of microalgae and bacteria. Meiofauna have been shown to influence primary production, nutrient cycling and other benthic metabolic processes{Carman et al :1996, 1997, 2000, Manini et al, 2000Pinckney et al:2003}.

  Organic matter {and nutrients} grazed by meiofauna are

assimilated or egested. When an animal dies, remineralized nutrients become available for microbial processes and primary production {Coull,1999}.

  Because of the short generation time of meiofauna {weeks to

months},these processes may result in a relatively rapid cycling of nutrients through the meiobenthos.

Utilization of microalgae, microbes and detritus by benthic meiofauna facilitates energy and nutrient transfer to higher trophic levels in benthic food webs {Coull, et al:}

II. Objective: 

-To determine the meiofaunal composition of RP 2 of ZSCMST POND -To determine the vertical zonation of meiofauna in RP 2 of ZSCMST POND

  III. Significance of the study: 

-The study is deemed significant as it will provide insight on the meiofaunal contribution to the general food web in the pond.

 IV. Scope and limitation:  

-The study is limited to the vertical zonation and identification of the meiofauna in Rearing Pond 2.

CHAPTER 2REVIEW OF RELATED LITERATURE

Several studies reported that nematoda is the most dominant taxa in the sediments {Rao,1987, Lee et al, 2003:Higgins and Thiel, 1988 and http://www.uft.uni-bremen.deoekilogieMeiofaunaReport.pdf,2006}.

The class Nematoda consists of two subclasses, the Secernentea and the Adenophorea. The main diagnostic characters are the presence of caudal glands{secreting a sticky fluid},bristles, and conspicuous amphids in the majority of Adenophorea, being either absent or insconspicuous in the Secernentea. {Franz Riemann,1989}

Nematodes are usually bound to a substrate. They can be brought into suspension by water column together with seston particles. Every type of sediment is colonized by nematodes, from almost dry dune sand to beach sand, coarse shell sublittoral grounds to hadal trenches. Many nematodes do not need a rich oxygen supply and may be regarded as facultative anaerobes. {Franz Riemann, 1979}.

Foraminifera

-These are classified as an order within the class Granuloreticulosea because they posses delicate, filiform, granular pseudopodia which branch and anastomose. All foraminifera are testate, although some primitive forms may be able to leave their granuloreticulate and pseudopodia.{Marszaleck, Wright, and Hay, 1969}.

Ostracoda

-are small crustaceans ranging in length from 0.08 to 32mm. Their entire body is encased in a bivalved, calcified carapace which can be smooth to variously ornamented. The two valves are joined by a dorsal hinge opposed by closing muscle. The body is unsegmented and has a reduced number of limbs. The head is larger than boyh the thorax and abdomen combined. Ostracods are found in nearly all aquatic environments {Dietmar Keyser}.

Polychaeta

 

Polychaetes are generally abundant in all soft substrata, except for the coarsest sands. They are segmented worms, with each body segment bearing paired, biramous{twobranched}appendages, termed parapods, which may be variously modified according to the worms mode of living. The two lobes of each parapod typically bear bundles or rows of bristles, or chaetae, which may be important in identification{Higgins and Thiel 1988}.

 

Oligochaeta

  Microdile oligochaetes are generaaly slender and flexible, and they often exhibit jerking movements. Several species are reddish, brownish or orange due to the coloration of the blood or the chloragogen tissue covering the gut. Some species are colorless and transparent, others conspicuously white. {Gierre and Pfannkuche 1982}. The estuarine and marine environments harbor a diverse fauna of small oligochaetes. Virtually any kind of marine sediment contains at least one oligochaete species, although not always in very high densities.{Christer Erseus}.

Turbellaria

 

Turbellarians are acoelomate bilateria without a definitive anus. They are largely free-living with a cellular, usually viliated, epidermis. The worms are often dorsoventrally flattened with anterior sensory and glandular regions. Turbellarians are ubiquitous forms in freshwater and marine habitats and very many associate with other organisms to various degrees {some are parasitic}. The main factors which control the life and distribution of turbellarians in eulittoral and sublittoral zones {marine, brackish, limnic} are temperature, salinity, organic content, and grain size. These factors either operate directly or influence such factors as pore size and drainage. Also important are water content and the availability of oxygen and food. {Lester R. G. Cannon and Anno Faubel}.

 

Gastrotricha

 

Members of this phylum are small, strap or tenpin-shaped, acoelomate worms. Most adults are less than 1mm in length, some species are less than 100 microns, and others exceed 3mm. The bodymis flattened ventrally and arched dorsally. It is divided into two regions, the head and trunk, which are often externally indistinct. The head bears the mouth, a tubular nematode-like pharynx, and the brain. All gastrotrichs have ventral locomotory cilia, and with them, glide smoothly over the substratum.

 

Gastropoda

 

Gastropods sometimes lack a shell, gill and cephalic disc, but are provided with one or two pairs of free head appendages {tentacles, rhinophores,}axial hump, and subepidermal spicule formations.

 

Insecta

 

Members of the class Insecta may be distinguished from all other arthropods by the presence of 3 principal body regions: head, thorax and abdomen, coupled with the presence of 3 pairs of thoracic legs at some stage during the life history of the animal. However, these ground-plan characters are often not displayed by the immature stages of some orders.

CHAPTER IIIMETHODOLOGY

I. Location and Duration of the Study:

-The study was conducted in the Rearing Pond 2 of Zamboanga State College of Marine Sciences and Technology {ZSCMST} for a period of 90 days.

 

II. Materials and Methods:

 

Materials for collecting/sieving/fixing the quantitative samples:

 

-12 corer sampler with a length of 10cm and an inner diameter of 5cm, 48 plastic containers, sieves{250 microns and 1mm}, graduated cylinder {1000ml}, Petri dish, wash bottle, 5% Rose Bengal solution, 144 liters of filtered seawater, camera.

 

Materials for analysis of the quantitative samples:

 

-photomicrograph, stereo and compound microscope, photos of meiofauna {By:Higgins and Thiel}.

III. Sampling:  The time of the day when the samples were collected was about

7:00 o’clock in the morning in January 2011. There were four{4} stations included and replication of samples was also implemented. A core sampler{modified from http://www.in-tres.com/articles/meps/133m/133p155.pdf,2007 }.was used in collecting sediment amples that are subject for meiofaunal extraction. The inner diameter of the core is 5cm and the length is 10cm. The sediment samples were collected by pushing the core sampler on the substrate. Upon its withdrawal,the opening was covered by the palm of one hand to avoid the sediments from spilling out, and each core was cut in 4 slices from particular layers;{0-2cm, 2-4cm,4-6cm,6-8cm}.[modified from http://www.esf.edu/schulz/Marine Ecology/Meiofauna.html.]. The sediment slice{subsample} were transferred immediately into a plastic container. The identification of the samples includes two letters and one no., the first leter refers to the station; the second refers to the no. of replicate; and the no. indicates the layer; 2 for the first layer{0-2cm}, 4 for the second {2-4cm}’ 6 for the third{ 4-6cm}and 8 for the fourth layer{6-8cm}.

IV. Fixing and Sieving:

 

A 5% formalin solution was used to fix the specimen in the sediment prior to extraction{adjusted concentration from 10% in http://www.en-wikipedia.org/wiki/Meiobenthos,2007 }. Sieving of specimens {meiofauna} were done in Aquatic Biology Laboratory. A simple decantation technique [adopted from http://www.en-wikipedia.org/wiki/Meiobenthos2007 ] was conducted using a 1000ml of graduated cylinder. This was done by pouring each of the sediments samples inside the cylinder, the other hand held the bottom. The cylinder was inverted slowly for several times and the sediment was allowed to settle for 1 min. The supernatant was filtered through 1mm and 250 microns sieves. The collected specimens{meiofauna} were removed from the sieve using wash bottle and collected in Petri dish. A 1% Rose Bengal solution adopted from the methods of Higginss and Thiel {Introduction to Meiofauna} was used in staining the specimens to facilitate counting and identification.

V. Meiofaunal Analysis:

 

The collected meiofauna were brought in the Hatchery and Wet Laboratory for documentation of the different specimens and it was done using photomicrograph. The organisms were classified in the main taxonomic group. Counting was done using compound microscope with the aid of a counting dish. Tallying of specimens was done upon counting. THE density unit used is the number of individuals per 31.416 cu. cm. of the volume of the sediment {subsample}. The morphological features of the specimen were referred to the photos of Meiofauna given by:{Introduction to Meiofauna by: Higgins and Thiel}.

Figure 1.FIELD SAMPLINGFigure 1.

MEIEOFAUNA REPRESENTATIVES .

Figure 2. Meiofaunal Representatives including fish larvae;(A & B) Nematoda spp.

(C) Foraminifera spp. (D)Ostracoda spp. (E) Turbellaria spp. (F) Polychaeta spp. (G) Oligochaeta spp. (H) Gastrotricha spp. (I) Insecta spp. (J) Gastropoda spp. (K). Fish Larvae

Table 1. taxonomic and Abundance of Mieofauna in the Sedimaent at 4 different depth Layers and 4 sampling stations

TaxonomicComposition

LAYER 1

S1 S2 S3 S4 Total %Distribution

Nemotoda 9 10 99 78 196 34.32.%Poly -chaeta 0 0 0 0 0 0%

Oligochaeta 1 1 1 4 7 50%

Foraminifera10 14 2 62 88 50.57%

Table 1. taxonomic and Abundance of Mieofauna in the Sedimaent at 4 different depth Layers and 4 sampling stations

TaxonomicComposition

LAYER 1

S1 S2 S3 S4 Total %Distribution

Ostracoda 11 11 6 1 11 17.57%

Gastropada 0 1 0 6 7 35%

Turbellaria 7 2 0 1 10 58.82%

Gastrotrciha 2 0 0 0 2 28.578%Insect 0 0 0 0 0 0%

Table 1. taxonomic and Abundance of Mieofauna in the Sedimaent at 4 different depth Layers and 4 sampling stations

TaxonomicComposition

LAYER 2

S1 S2 S3 S4 Total %Distribution

Nemotoda 7 7 51 44 109 19%

Poly -chaeta 0 0 0 1 1 33.33%

Oligochaeta1 0 0 1 2 14.28%

Foraminifera11 6 1 20 38 21.8%

Table 1. taxonomic and Abundance of Mieofauna in the Sedimaent at 4 different depth Layers and 4 sampling stations

TaxonomicComposition

LAYER 2

S1 S2 S3 S4 Total %Distribution

Ostracoda 8 3 1 9 21 12.731%

Gastropada 0 0 0 5 5 25%

Turbellaria 2 1 0 0 3 17.6%Gastrotrciha 0 0 0 0 0 0%

Insect 0 0 0 0 0 0%

Table 1. taxonomic and Abundance of Mieofauna in the Sedimaent at 4 different depth Layers and 4 sampling stations

TaxonomicComposition

LAYER 3

S1 S2 S3 S4 Total %Distribution

Nemotoda 7 4 23 48 82 14.4%

Poly -chaeta 1 0 0 0 1 33.33%

Oligochaeta 0 0 0 2 2 14.28%

Foraminifera8 4 1 14 27 15.52%

Table 1. taxonomic and Abundance of Mieofauna in the Sedimaent at 4 different depth Layers and 4 sampling stations

TaxonomicComposition

LAYER 3

S1 S2 S3 S4 Total %Distribution

Ostracoda 11 3 1 9 24 14.54%

Gastropada 0 1 0 4 5 25%

Turbellaria 2 0 0 1 3 17.6%Gastrotrciha 2 0 0 0 2 28.57%

Insect 0 0 0 0 0 0%

Table 1. taxonomic and Abundance of Mieofauna in the Sedimaent at 4 different depth Layers and 4 sampling stations

TaxonomicComposition

LAYER 4

S1 S2 S3 S4 Total %Distribution

Total

Nemotoda 6 4 33 141 184 32.2% 57Poly -chaeta 0 1 0 0 1 33.33% 3

Oligochaeta 0 1 0 2 3 21.42% 14

Foraminifera8 2 5 6 21 12.1% 174

Table 1. taxonomic and Abundance of Mieofauna in the Sedimaent at 4 different depth Layers and 4 sampling stations

TaxonomicComposition

LAYER 4

S1 S2 S3 S4 Total %Distribution

Total

Ostracoda 8 5 1 17 91 55.15% 165

Gastropada 0 0 0 3 3 15% 20

Turbellaria 1 0 0 0 1 5.9% 17

Gastrotrciha 2 1 0 0 3 42.85% 7Insect 0 0 1 0 1 100% 1

CHAPTER IV RESULTS AND DISCUSSION 

The study was conducted in the Rearing Pond 2 of Zamboanga State College of Marine Sciences and Technology (ZSCMST) during the month of December to February 2011. Collection of samples were made at daytime and it was about 7:00 o’clock in the morning in January3, 2011. A total of nine (9) taxa were identified in the entire duration of the study (see Table1) these are; Nematoda, Foraminifera, Ostracoda, Oligachaeta, Gastropoda, Turbellaria, Polychaeta, Gastrotricha, Insecta including Fish Larvae. Four (4) were observed to be constantly present in all four (4) Layers (0-2 cm, 2-4cm, 4-6cm, 6-8cm) and four (4) sampling stations.

Oxygen availability is one of the main factors that condition the vertical distribution of Meioauna (Coull, 1988), The Nematoda were the dominant group in this stady and several studies reported that Nematoda is the most dominant taxa in the sediments (Rao, 1987; Lee et al, 2003; Higgins and Thiel, 1988 and http://www.uft.uni-bremen.deoekilogieMeiofaunaReport.pdf, 2006) (as stated in Chapter 2)

As we can see in Table 1, Nematoda group in the fourth Layers (station 4) show a high densities and according to Franz Rieman, 1979, many nematodes do not need a rich oxygen supply and maybe regarded as facultative anaerobes, so it is possible to find nematodes in the deeper layers.

The oxygen availability limits the distribution of several meiobenthic groups that can be found almost exclusively in the first layer (2cm) depth, (Oligachaeta, Foraminifera, Ostracoda, Gastropoda, Turbellaria). Although the groups Nematoda. Foraminifera, Ostracode often show higher densities in the first layer (2cm), they also attain high values and sometimes higher in lower layers. Apparently, the groups Polychaeta and Oligochaeta don’t show high densities, since they are active diggers according to Erseus (1980) they can live at depths greater than 8cm, used in this study, this can explain why it is not possible to find high densities.

Coull (1973) emphasized that nematodes regularly dominate the meiofauna in sediment biotopes comprising 50% of the meiofauna. He stated further the copepods are usually in the abundance but may dominate in some course grained sediments. However, results of this study showed that Foraminifera is the dominance to nematodes as mentioned in the study of Lee et al, (2003) followed by Ostracoda and other taxa with a much lesser abundance.

As can be seen in Table 1, the foraminifera were greater in the first layer, (station 2 and station 4) decreasing with depth and according to Gooday (1988), the sarcomastigophora group is generally found near the sediment surface where they can find nutrients and interstitial water is well – gerated. Since these organisms feed on algae (Gooday 1988) and the food availability is higher on the sediment surface. However, in station 1, some foraminifers, increase as depth increases, although, according to Moodley et al (1988) the foraminifers (Sarcomastigophora) can migrate through anoxic zones what suggests that some author (1988) the sulphied concentration (often correlated with the absence of oxygen) may be important to determine their distribution, since they tolerate sulphide but only for survival effects, as they do not reproduce in its presence.