Integration of technologies for understanding the functional relationship between reef habitat and fish growth and production

Functional linkage between reef habitat quality and fish growth and production has remained elusive. Most current research is focused on correlative relationships between a general habitat type and presence/absence of a species, an index of species abundance, or species diversity. Such descriptive information largely ignores how reef attributes regulate reef fish abundance (density-dependent habitat selection), trophic interactions, and physiological performance (growth and condition). To determine the functional relationship between habitat quality, fish abundance, trophic interactions, and physiological performance, we are using an experimental reef system in the northeastern Gulf of Mexico where we apply advanced sensor and biochemical technologies. Our study site controls for reef attributes (size, cavity space, and reef mosaics) and focuses on the processes that regulate gag grouper (Mycteroperca microlepis) abundance, behavior and performance (growth and condition), and the availability of their pelagic prey. We combine mobile and fixed-active (fisheries) acoustics, passive acoustics, video cameras, and advanced biochemical techniques. Fisheries acoustics quantifies the abundance of pelagic prey fishes associated with the reefs and their behavior. Passive acoustics and video allow direct observation of gag and prey fish behavior and the acoustic environment, and provide a direct visual for the interpretation of fixed fisheries acoustics measurements. New application of biochemical techniques, such as Electron Transport System (ETS) assay, allow the in situ measurement of metabolic expenditure of gag and relates this back to reef attributes, gag behavior, and prey fish availability. Here, we provide an overview of our integrated technological approach for understanding and quantifying the functional relationship between reef habitat quality and one element of production – gag grouper growth on shallow coastal reefs

Technological Change and the Politics of Decarbonization: A Re-making of Vested Interests?

publishedVersio

Effect of the T90-codend on the catch quality of cod (Gadus morhua) compared to the conventional codend configuration in the Barents Sea bottom trawl fishery

The aim of this study was to compare the catch quality of Northeast Atlantic cod (Gadus morhua) in the Barents Sea bottom trawl fishery caught using the conventional configuration (a sorting grid followed by a diamond mesh (T0) codend) and a T90° turned mesh codend (T90) without a grid. Twenty hauls were conducted, consisting of 10 hauls with the conventional configuration and 10 hauls with the T90-codend. The catch quality was assessed using the catch-damages-index (CDI) and a newly developed method using VIS/NIR hyperspectral imaging to estimate the residual blood abundances in the fish muscle. The probability of obtaining fish with no damage was 23.4% (CI: 16.3–31.1%) for cod captured by the conventional configuration, and 21.2% (CI: 15.4–27.2%) for cod captured by the T90-codend. The average blood abundance (in arbitrary unit) was 0.86 (CI: 0.85–0.87) for cod captured by the conventional configuration and 0.88 (CI: 0.87–0.88) for cod captured by the T90-codend. Catch quality of the hauls obtained using the two gears did not differ significantly in terms of catch damage or residual blood levels in the cod. Hence, this study demonstrated that T90-codends do not compromise catch quality compared to regular diamond meshed codends.publishedVersio

Lepidopteran defence droplets - a composite physical and chemical weapon against potential predators

Insects often release noxious substances for their defence. Larvae of Zygaena filipendulae (Lepidoptera) secrete viscous and cyanogenic glucoside-containing droplets, whose effectiveness was associated with their physical and chemical properties. The droplets glued mandibles and legs of potential predators together and immobilised them. Droplets were characterised by a matrix of an aqueous solution of glycine-rich peptides (H-WG(11)-NH(2)) with significant amounts of proteins and glucose. Among the proteins, defensive proteins such as protease inhibitors, proteases and oxidases were abundant. The neurotoxin β-cyanoalanine was also found in the droplets. Despite the presence of cyanogenic glucosides, which release toxic hydrogen cyanide after hydrolysis by a specific β-glucosidase, the only β-glucosidase identified in the droplets (ZfBGD1) was inactive against cyanogenic glucosides. Accordingly, droplets did not release hydrogen cyanide, unless they were mixed with specific β-glucosidases present in the Zygaena haemolymph. Droplets secreted onto the cuticle hardened and formed sharp crystalline-like precipitates that may act as mandible abrasives to chewing predators. Hardening followed water evaporation and formation of antiparallel β-sheets of the peptide oligomers. Consequently, after mild irritation, Zygaena larvae deter predators by viscous and hardening droplets that contain defence proteins and β-cyanoalanine. After severe injury, droplets may mix with exuding haemolymph to release hydrogen cyanide