The biological carbon pump plays a crucial role in the regulation of Earth's climate and the distribution of biogeochemical properties in the ocean, by exporting to the deep ocean CO 2 that is fixed into biomass during photosynthesis in the sunlit surface layer, through the sinking of particles and their subsequent remineralization. Phytoplankton requires macro-nutrients for the synthesis of organic matter. Nitrogen (N) is considered as one of the most important nutrients since it limits productivity in many oceanic regions (Moore et al., 2013). The North Atlantic Ocean, which hosts one of the most productive spring phytoplankton blooms of the world's ocean (Longhurst, 2007), is estimated to be a significant contributor to the global oceanic export production (Falkowski et al., 1998;Sanders et al., 2014).The North Atlantic Ocean is characterized by the classical double gyre system of the subtropical and subpolar gyres (Figure 1). Both gyres harbor contrasting physical and biogeochemical features (Sanders et al., 2014) and are separated by a strong transition area, the North Atlantic Current (NAC). In addition, the Atlantic Meridional Overturning Circulation is a key component of the Earth's climate system, with the NAC carrying a northward flow of warm and salty waters balanced by a southward flow of colder deep waters (North Atlantic Deep Water) (Buckley & Marshall, 2016). The North Atlantic subtropical gyre is considered to be a year-round stratified oligotrophic N-limited area (Moore et al., 2008(Moore et al., , 2013, where N 2 fixation performed by diazotrophs plays an important role in providing fixed N (or bioavailable N) to the surface waters (Capone et al., 2005(Capone et al., , 2008. In contrast, a strong seasonality is observed in the North Atlantic subpolar gyre. The relief of winter light limitation induces the onset of a spring phytoplankton bloom supported by

Lack of proper scientific data on the behaviour of cetaceans is a major constraint in managing whale and dolphin watching activities without affecting cetacean populations in marine waters off Mirissa, where it has become a high income generating tourist activity. Therefore a shipboard surveys were conducted using a special whale watching boat for 43 days from January to April 2012 in an area of about 940 km 2 in Mirissa, southern coast of Sri Lanka to identify the environmental parameters that affect the abundance of cetaceans. During this study, 8 cetacean species including 6 toothed whale species (Physeter macrocephalus, Globicephala melas, Peponocephala electra, Orcinus orca, Tursiops truncates and Stenella longirostris) and two baleen whale species (Balaenoptera musculus and Balaenoptera physalus) were identified. Results of the study revealed that relationship between species occurrence and the measured water quality parameters (temperature, salinity and density) was significant (p < 0.05). From the identified species blue whale and melon headed whale can tolerate high density (1.02±0.0) and salinity (blue whale-36.35±0.75; melon headed-35.55±0.51) range while blue whale (28.53±0.89), sperm whale (28.47±0.93) and spinner whale (28.66±1.04) can tolerate widee temperature range.

Scientific information is vital to the conservation of cetaceans and the management of whale-watching activities. The southern coastal waters of Sri Lanka are near a narrow continental shelf and biologically abundant in cetacean species. Although the occurrence of cetaceans has been investigated in certain waters of Sri Lanka, few surveys have been conducted along the southern coast. To fill this gap, we conducted boat-based surveys from January to May 2017 to investigate the occurrence, diversity, and behavior of cetaceans in the waters off Mirissa, covering a survey area of 788.9 km 2 . During 55 survey days, we recorded a total of 242 cetacean sightings and identified at least 9 species (3 mysticetes and 6 odontocetes). The blue whale was the most common mysticete species (167 of 174 mysticete encounters), followed by the Omura's whale (4 of 174) and Bryde's whale (3 of 174). The spinner dolphin was the most common odontocete species (28 of 68 odontocete encounters), followed by the sperm whale (18 of 68), common bottlenose dolphin (13 of 68), short-finned pilot whale (5 of 68), melon-headed whale (2 of 68), and killer whale. Blue whales and sperm whales exhibited a clear preference for outer shelf and high slope areas, and blue whales were observed feeding along these waters. The present study provides near-baseline information on cetacean occurrence and diversity in whale-watching waters off southern Sri Lanka, and highlights the urgent need for proper management strategies for whale-watching activities.

Purpose: Live rocks are very important and highly demanded in the global aquarium industry and can be cultured easily without sophisticated techniques or knowledge. Marine Live rock culture may become a conceivable alternative industry among the resource utilizing coastal communities in Sri Lanka. However, it has not been scientifically studied yet. Research Method: Nine types of cement rocks were made by changing three types of shapes and three types of substrates and those were placed in different study locations on the Southern and Eastern coast of Sri Lanka covering all four types of monsoon patterns prevail in the country. Findings: Live species attachments, their attachment rates, and consumer preferences differed with the shape, substrate, monsoon pattern, study location, and growth period in the sea and most of those differences were statistically significant. Consumer preference was mainly dependent on the nature of biota attachments on top of the different rock types. Therefore, their preferences were also changing with the types of rock, monsoon pattern, and location. Originality/ Value: Findings can be effectively utilized for establishing live rock culture as an alternative industry, especially in ecosystems where resources are depleted or degraded.