Comparitive studies

The implementation of artificial reefs is one effort used to mitigate the rate of decline of coral reefs and the deterioration of fish communities. Artificial reefs add support to struggling reefs habitats by providing additional or varied structural relief, sometimes mimicking specific coral structure types. The purpose of this study is to assess the effectiveness of branching artificial reef (BAR) habitat deployed in November 2011 by comparing the fish density and biomass, and species richness and diversity of the BAR to those of habitats in which it was placed. Three plots of BAR habitat were compared to three plots of rubble habitat and three plots of fore-reef habitat. BAR plots were found to have significantly lower fish density, fish biomass, and species richness than the fore-reef, but no statistical difference in species diversity. When compared to the rubble, BAR habitat showed significantly higher species richness, but no significant difference in density, biomass, or diversity. A comparison of family and fish phase community composition revealed that BAR habitat supports significantly more initial phase Scaridae than either adjacent habitat. It was concluded that BAR habitat adds little in the way of a complementary habitat to the terrace-fore-reef zone. The results from this study suggest that no further implementation of this form of artificial reef should be carried out along the rubble terraces of Bonaire. However, further monitoring of the BAR habitat and research into a branching structure with greater complexity, more interstitial matrix and constructed from calcareous material may be useful.

This student research was retrieved from Physis: Journal of Marine Science XI (Fall 2012)19: 88-95 from CIEE Bonaire.

Abstract

Several hypotheses have been proposed to explain the limitation of brain size in vertebrates. Here, we test three hypotheses of brain size evolution using marine teleost fishes: the direct metabolic constraints hypothesis (DMCH), the expensive tissue hypothesis and the temperature-dependent hypothesis. Our analyses indicate that there is a robust positive correlation between encephalization and basal metabolic rate (BMR) that spans the full range of depths occupied by teleosts from the epipelagic (< 200 m), mesope- lagic (200–1000 m) and bathypelagic (> 4000 m). Our results disentangle the effects of temperature and metabolic rate on teleost brain size evolution, supporting the DMCH. Our results agree with previous findings that teleost brain size decreases with depth; however, we also recover a negative corre- lation between trophic level and encephalization within the mesopelagic zone, a result that runs counter to the expectations of the expensive tissue hypothesis. We hypothesize that mesopelagic fishes at lower trophic levels may be investing more in neural tissue related to the detection of small prey items in a low-light environment. We recommend that comparative encephalization  studies control for BMR in addition to controlling for body size and phylogeny.