Dear all,
I'm reacting to the stimulating message by Joalanta Koszteyn, who reminds us what life is - development and life cycle, behavioural and ecological adaptation, i. e. the relations of an organism with the environment. Each researcher can apply Jolanta's definition to the his/her case study.This would represent a key to answer to the basic question by Erik Bonsdorff: can we compare Baltic with other Oceans? Let's ask this question to life itself.
I asked such question to Talitrus saltator, a well known wide spread species from the Mediterranean to the southern Baltic coasts.
A genetic comparison through allozymic analysis of populations from Mediterranean and southern Baltic coasts was recently made by Valerio
Ketmaier and co-workers. Two main clusters of populations were recognised that split at an average distance value of D=0.4, the west-Mediterranean and the East-Mediterranean, the former including the Baltic population analysed, which splits at a D=0.275. Talitrus saltator is also a structered species, which has probably colonised the Atlantic and the Baltic from the Mediterranean. More considerations can be made regarding intrapopulation variation and its relation to coastal stability.
We also compared behavioural adaptation of these populations and interpreted differences as adaptation to different environmental constraints. The Baltic offered the opportunity to discriminate which adaptations were specific to tidal excursions (high tidal excursion in the Atlantic; low in the Mediterranean and the Baltic), and which to climatic differences (low temperatures in the north Atlantic and the Baltic, and high in the Mediterranean). The basic and inborn phototactic response appeared flexible in the Atlantic populations, and this would favour wide daily migrations of the adults to avoid tides. As to scototactic behaviour and its daily variation, the adaptation of Baltic individuals was more similar to the behaviour of laboratory born Mediterranean ones than to adults collected from Mediterranean shores.
We could speculate further on these results, but the sense of my message is that the Baltic, the Mediterranean Seas and the Atlantic Ocean are certainly comparable regarding life styles and adaptation of organisms. We would learn a lot comparing adaptations of organisms, as well from interactions between Mediterranean and Baltic researchers.
Cited papers:
Ketmaier V., Scapini F., De Matthaeis E., (2003) Exploratory analysis of talitrid population gentics as indicator of the quality of sandy beaches, Estuarine Coastal and Shelf Science 56 (in press)
Nardi M., Persson E.-E- and Scapini (2000) Diel variation of visula response in talitrus saltator and Talorchestia dehayesii (Crustacea:Amphipoda) from high latitude beaches of low tidal amplitude, Estuarine, Coastal and Shelf Science 50, 330-340.
Warmest regards to all
Felicita |
