The middle intertidal zone

By Robin Johansson, Jenni Olausson, Jennifer Palmeborn

and Sofia Roslund

Materials & Methods Camera Water objective Microscope Magnifing glas Bucket

Looked at the beach, and did a short analyze.

Turned rocks and algeasto find organisms

A few samples were putin a bucket and analyzedin a microscope back at the ship

Checked what kind of species that was found

Made notes about the mesolitteral zone in general

The middle intetidal zone

Between the highest and the lowest tide More exposed to abiotic factors The organisms have to adapt their lifestyles

because of the regular tides Plants need to be able to protect themselves

from drying out Most of the organisms use shells for

protection against the winterwater and otherpredators.

The environment The beach was cloose to a busy harbor with many

kinds of vessels. The water was very muddy and it was hard to see

longer than half a meter down. It was caused by the sedement which had blended around with the water.

It was not only this that made the water muddy there was also garbage and dumping from the leasureboats close by.

The beach was rocky and the bottom was clayey. The vegetation was low and also the number of

speaces.

The upper middle intertidal zone This zone is a bit dryer, then the lower parts of

the middle intertidal. Its not common to find organisms living on the

sand area, they usualy hide beneth and behind stones etc. to be prepered for tides, and to keep a little bit wet

The environment of the upper zone A lot of sediment, sand and Calcium

Carbonate, maybe from the delta Many rocks, occupied by oysters,

barnicals and algeas Most of the sand was wet and muddy,

especially further down. It became dryer the closer you got to the

rockey part of the zone The entire middle intertidal was shaped by

wave splasches and other abiotic factors

The most common organisms in the middle intetidal zone

Organisms Crassostrea gigas Algeas like Ulva Lactuca Barnicals Crabs, Carcinus Maenas Seaweed Mytulis edulis Tiny organisms like Ligia

Oceanica (live on rockeybeaches) and Copepoda(Tisbe)

Crassostrea gigas

Crassostrea gigas belongs to the phylum Bivalvia

It has an asymetrical, long and thin body and can be up to 30 cm long.

Apart from its body they allso have an lillaccolored scare next to the sphincter that makes them different from other oysters.

The bottom shell is concave and the upper shell is more flat but still concave.

The form is varying depents on the bottom and other condictions.

Crassostrea gigas comes from the Japanse cost but has been spreed allmostall over the world. Becauce of more or less sucessful oysterfarming.

Ulva lactuca Ulva lactuca can be up to 20 cm high/wide

It looks like a green and thin lettuce

There is two kinds of Ulva lactuca:There is the light green one thats just one cell thick and the dark green

one thats 2 cell thick.

Its comon near the shore where the wateris moving

It use to cling fast to stones

It use to live on up to 1 m deept but it have been found at 15 m deep in the baltic sea

BarnicalsSemibalanus balanoides

The shell is up to 2 cm in diameter and 1-6 cm high.

They usually grow on rocks and other hardmaterials.

Barnicals are mostly covered by water in high tides.

They can survive in dryer periods, when its lowtide, and lower temperatur in the winter time.

The shells grow very close to eachother, mainlybecause of the lack of space.

Results & Discussion

There was a lot of sessile organisms Crassostrea gigas was the most comon

organism, high salinity Lots of junk, human factors Hiding / keep wet

List of references

Kie, M. (2004). Havets Djur. Kpenhamn; Nordisk Forlag A/S

Kemp,M-J. (2007). Marine Biology sixthedition. New York; McGraw-HillCompanies

Anderberg, S, A. (2007). Havet-Illustreratuppslagsverk. London; Globe Frlaget

Johnsson, L. (2001). Bildkompendium Marina Evertebrater. Tjrn; -

The middle intertidal zone Materials & MethodsThe middle intetidal zoneThe environmentThe upper middle intertidal zoneThe environment of the upper zoneThe most common organisms in the middle intetidal zoneCrassostrea gigasUlva lactucaBarnicalsSemibalanus balanoidesResults & DiscussionList of references