Marine Ecology-An Evolutionary Perspective最新文献

To implement effective management and conservation strategies, an understanding of the spatial ecology, habitat preferences and movement of demersal elasmobranchs is required. This study combines a photographic survey obtained from an autonomous underwater vehicle (AUV) with existing bathymetric data to help understand elasmobranch ecology within the Firth of Lorn, western Scotland. This area is within the Loch Sunart to Sound of Jura Marine Protected Area (MPA) and designated for the protection of the critically endangered flapper skate (Dipturus intermedius). Two areas of seabed were surveyed using an AUV in water depths of 110–165 m southwest of the Isle of Kerrera. Eight surveys were conducted in total, four in each area. Each area was surveyed twice over 2 days in October 2020 and twice in 2 days in May June 2021. One day used bait on the seabed (October) whilst all the others had no bait. For each survey, the AUV travelled 17 km at a height of 2 m above the seabed in a lawnmower pattern providing 0.5 km² photographic coverage for ~2 h per survey. Five elasmobranch species, two scyliorhinids (Scyliohinus canicula and Galeus melastomus) and three rajiformes (D. intermedius, Raja clavata and Leucoraja naevus), were identified from a total of 43 k seabed photographs. In total 42 individual animals and 7 egg cases were observed. Although the AUV had short survey times and small study areas the results are encouraging for AUVs being a useful tool in understanding elasmobranch ecology.

Ikeda pirotansis (Menon and DattaGupta 1962), previously known only from intertidal habitats, is now reported for the first time from subtidal habitats in Kuwait, northwestern Arabian Gulf. This finding eliminates its ecological separation from its congener Ikeda taenioides, which is endemic to Japan. The comparison of proboscis morphology (shape, length and colour pattern) between intertidal and subtidal I. pirotansis shows no significant differences. Furthermore, mtDNA extracted from proboscis samples and analysed for the COX1 gene revealed no genetic distance between intertidal and subtidal samples, confirming that I. pirotansis also colonises subtidal habitats. Phylogenetic analysis indicated that the I. pirotansis from Kuwait and India clustered together, forming a monophyletic clade, and warrants more extensive regional sampling to study the detailed taxonomic and evolutionary history of the order Echiuroidea.

The early marine migration of Atlantic salmon through coastal areas and fjords is a potential bottleneck in the migration where high losses can occur. Here we use a displacement experiment to attempt to identify mortality hotspots or bottlenecks within a fjord in Western Norway, where earlier studies have indicated exceptionally high mortality and poor recruitment over multiple years. Atlantic salmon (Salmo salar) smolts from the Dale River were tagged with prediction sensor acoustic transmitters and released at one of six sites within the fjord, which was covered by several receivers up to a large bridge across the fjord. There was a consistently high level of mortality throughout the migration, where none of the smolts from the first three release groups made it past the bridge to the outer fjord (mean survival = 17%). There was a strong effect of release distance on survival, suggesting that releasing the fish further out in the fjord and closer to the bridge improved survival. Mark-recapture analysis revealed the importance of the predation sensors for calculating survival; without using the information from predation sensors, survival through the system was high and the confidence bands were narrow; however, knowing which individuals had been eaten reduced estimated survival substantially. Once smolts arrived at the end of the tracking array at the bridge, passage of the bridge was slow, and we found that salmon spent time moving laterally along the structure rather than directly through it and appeared to be delayed.

The Gulf of Aden (GA) experiences seasonal upwelling phenomena, fostering favorable conditions for diverse marine life. Despite this richness, the known sea urchin species in the Gulf of Aden has been limited to the common long-spined (Diadema paucispinum). Our study aimed to explore and document sea urchin diversity in this region. Through scuba diving and low tide collections from coral reefs and sandbanks, we obtained samples along the Hadhramout coast, spanning from the Qusayr area to the Aden Province coast, including Azizi Island opposite Ras Imran and the sub-district of the city of Aden. This survey revealed five sea urchin species, expanding the known taxa. For the first time in the Gulf of Aden, we qualitatively registered two regular and three irregular sea urchin species: Heterocentrotus mammillatus (Linnaeus, 1758), Stomopneustes variolaris (Lamarck, 1816), Echinodiscus bisperforatus (Leske, 1778), Clypeaster humilis (Leask, 1778), and Lovenia elongata (Gray, 1845). These findings contribute to our understanding of the Gulf biodiversity and emphasize the need for continued exploration in this region.

The pink shrimp (Penaeus notialis) constitutes an important commercial fishery in the Colombian Caribbean. However, due to the lack of biological data and fisheries management information led to the overexploitation and collapse of the shrimp fishery. Despite the economic and commercial importance of this fishery in the Colombian Caribbean, no studies have been carried out on the growth and mortality of pink shrimp. The objective of the present study was to estimate for the first time robust von Bertalanffy growth parameters, mortality rates with empirical formulae and the length-converted catch curve of the commercial pink shrimp (P. notialis) in the Colombian Caribbean. The samples were collected between June 2012 and May 2013, between Cartagena and the Gulf of Urabá. The parameters of the growth were estimated using the electronic Length frequency analysis. We calculated the natural mortality (M) with the K and L_∞ parameters. A total of 5199 pink shrimp were collected. The estimates of growth parameters for P. notialis showed higher L_∞ (females: 171.91 mm; males: 135.37 mm) and W_∞ in females (44.74 g) than in males (19.44 g). The growth coefficient (K) was 0.74 in females and 1.19 in males. The t_a estimated for females was −0.12 and for males −0.04. The maximum age (t_max) of this species was 3.91 year for female and 2.47 year for male. The natural mortality rate (M) for female was (0.61 year⁻¹) and male (0.93 year⁻¹).

We report here the interaction between the environment and tintinnids inhabiting in the mangrove proximal zone waters of South Andaman, in relation to certain physicochemical (temperature, salinity, pH, and dissolved oxygen) and biological (Phytoplankton biomass) parameters. As the proximal zone of mangrove waters is subjected to regular tidal effect, tintinnids community was studied for one year (September 2012–August 2013) during the Northeast monsoon, Inter-monsoon, and the Southwest monsoon periods. We recorded a total of 26 species belonging to 18 genera, and the abundance of tintinnids varied seasonally and spatially with higher abundance during the Southwest monsoon (19–59 ind L⁻¹) followed by the Inter-monsoon (18–27 ind L⁻¹). Statistical analysis, such as Canonical correspondence analysis (CCA) and Spearman rank correlation, depicts that the influences of environmental variables varied seasonally, and temperature (r = 0.76–0.90), salinity (r = 0.90–0.1), and pH (r = 0.90–0.1) are the major variables influencing on tintinnids assemblages in the mangrove proximal zone waters of South Andaman.

The most well-known relationship is between sea anemones and decapod crustaceans, of which crabs are classic examples of mutualistic interactions in which both organisms benefit from living with zooxanthellae and hermatypic or reef-forming corals. A marine ecology study off the southern coast of Tamil Nadu revealed five types of sea anemones that cohabit symbiotically with other marine animals. These species include Stichodactyla haddoni (Saville-Kent, 1893), Entacmaea quadricolor (Leuckart in Ruppell and Leukart, 1828), Radianthus (=Heteractis) magnifica (Quoy and Gaimard, 1833), Radianthus (=Heteractis) crispa (Ehrenberg, 1834), and Calliactis polypus (Forsskal, 1775), are found in symbiotic associations. This observation revealed that the decapod porcelain crab Neopetrolisthes is associated with the sea anemones Radianthus and Entacmaea, whereas this has not been reported in Stichodactyla. The hermit crab anemone, C. polypus, is generally associated with hermit crabs, and we report this association for the first time in live gastropod, Turbinella pyrum (Linnaeus, 1767). A few animals (both the host and symbiont) were brought to the cnidarian laboratory at the ICAR-Tuticorin Regional Station of the CMFRI, where they were maintained in optimum seawater for further observations. The present study aimed to compare previous reports of symbiosis in decapod crustaceans and gastropods with sea anemones from Indian waters to provide insight into the dynamics of symbiosis in the Bay of Bengal Large Marine Ecosystem.

In this paper, we argue that the concept of ‘species’ should not be the main focus of research and policies in biodiversity conservation. Diversity is important at all levels of life: within species as well as among them and within and among ecosystems. First, we give a brief overview of the debate about the necessity to find a unified concept of ‘species’. In this, we side with Charles Darwin, who insisted that no strict definition could be given to this term, which is ultimately a matter of arbitrary and pragmatic human language. This did not worry Darwin, and neither should it concern biologists or ecologists today. Darwin's great discovery relied on a recognition of the many differences within species, not on their similarities. Next, we argue that the focus on species and the neglect of other diversity measures in the conservation discourse have led to problems in public perception of—and policies on—conservation and biodiversity. In areas with few species, intraspecific diversity is often of utmost importance to ecosystem processes and functions, and such regions may provide the environmental conditions that enable and promote the diversification of specialised subgroups in the absence (or reduction) of interspecific competition. We give some examples of these processes based on research in marine and freshwater ecosystems, focusing on Iceland and the subarctic region. Finally, we refer to alternative, emerging methodologies of assessing ecosystem health which go beyond the quantitative method of counting species and subspecies and instead emphasise more complex phenomena such as relations, interactions and processes. These approaches, we suggest, are consistent with the philosophical tradition called ‘process ontology’, and we argue that both ecological research and conservation policy can benefit from a process philosophical perspective. Finally, we briefly discuss our motivations for finding this topic to be of importance.