Abstract
Changes of taxonomic composition, morphology (total length) and reproductive mode of copepod assemblages between the cold and warm periods were studied in the Southern coast of Sfax, in relation with environmental factors and pollution degree (heavy metal concentration). Salinity, temperature and heavy metal concentration seem to be the most important factors influencing the total length during both sampling periods. A total of 23 different copepod species were identified during the survey period. The copepod abundance was higher in cold (74%; 9.78 ± 10.04 A— 103 ind m-3) than in warm (67%; 7.11 ± 8.81 A— 103 ind m-3) periods. This result could be attributed to an increase of temperature and salinity in August, which favors the development of smaller copepod species. During the cold season, larger adult broadcaster of calanoids species (total length between 0.98 and 1.22 mm) such as Acartia (Acartia) danae (Giesbrecht) (Tl = 1.22 mm), Paracartia grani (Sars) (Tl = 1.12 mm) and Paracartia latisetosa (Krichagin) (Tl = 1.06 mm) were associated to low temperature and salinity. During the warm period, smaller egg-carrying species of harpacticoids (total length between 0.18 and 0.3 mm) such as Harpacticus littoralis (Sars), Tisbe furcata (Baird) and Tigriopus sp. (Norman) were associated with high temperature and heavy metal pollution. H. littoralis displayed a very high abundance of ovigerous females (Nfo = 12.8 A— 103 ind m-3, representing 87.2% of total number of females) with high number of eggs per sac (E = 26 ± 2 egg sac-1).
Highlights
Most zooplankton organisms are very sensitive to physical, chemical and biological factors [1,2,3,4]
The present study revealed that copepods are vulnerable to temperature, salinity and heavy metal pollution
Smallsized harpacticoid species are more abundant in the warm season, i.e. H. littoralis T. furcata and Tigriopus sp. coupled with high salinity, temperature and high metal concentration
Summary
Most zooplankton organisms are very sensitive to physical, chemical and biological factors [1,2,3,4]. Copepods are the most abundant zooplankton assemblages in marine ecosystems [8,9,10] They play a pivotal role in aquatic food webs by transferring nutrient and energy from primary (e.g. phytoplankton) to tertiary (e.g. planktivorous fish) producers [11,12,13,14,15]. As they are highly dependent on environmental conditions (e.g. chemical and organic contaminants, temperature and salinity), copepod species have long been used as bioindicators of environmental quality and water mass origin [16,17]. Marine copepods can be an excellent tool for evaluating the impact of marine pollution throughout coastal regions because they quickly respond to different types of stress in different ways (e.g. decreased fecundity, mortality) [18,19,20,21,22]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
