Paolo Usseglio

Global human footprint on the linkage between biodiversity and ecosystem functioning in reef fishes.

A global survey of reef fishes shows that the consequences of biodiversity loss are greater than previously anticipated as ecosystem functioning remained unsaturated with the addition of new species. Additionally, reefs worldwide, particularly those most diverse, are highly vulnerable to human impacts that are widespread and likely to worsen due to ongoing coastal overpopulation.

The Growing Need for Sustainable Ecological Management of Marine Communities of the Persian Gulf

The Persian Gulf is a semi-enclosed marine system surrounded by eight countries, many of which are experiencing substantial development. It is also a major center for the oil industry. The increasing array of anthropogenic disturbances may have substantial negative impacts on marine ecosystems, but this has received little attention until recently. We review the available literature on the Gulf’s marine environment and detail our recent experience in the United Arab Emirates (U.A.E.) to evaluate the role of anthropogenic disturbance in this marine ecosystem. Extensive coastal development may now be the single most important anthropogenic stressor. We offer suggestions for how to build awareness of environmental risks of current practices, enhance regional capacity for coastal management, and build cooperative management of this important, shared marine system. An excellent opportunity exists for one or more of the bordering countries to initiate a bold and effective, long-term, international collaboration in environmental management for the Gulf.

Variation in fish density, assemblage composition and relative rates of predation among mangrove, seagrass and coral reef habitats

We tested the hypothesis for several Caribbean reef fish species that there is no difference in nursery function among mangrove, seagrass and shallow reef habitat as measured by: (a) patterns of juvenile and adult density, (b) assemblage composition, and (c) relative predation rates. Results indicated that although some mangrove and seagrass sites showed characteristics of nursery habitats, this pattern was weak. While almost half of our mangrove and seagrass sites appeared to hold higher proportions of juvenile fish (all species pooled) than did reef sites, this pattern was significant in only two cases. In addition, only four of the six most abundant and commercially important species (Haemulon flavolineatum, Haemulon sciurus, Lutjanus apodus, Lutjanus mahogoni, Scarus iserti, and Sparisoma aurofrenatum) showed patterns of higher proportions of juvenile fish in mangrove and/or seagrass habitat(s) relative to coral reefs, and were limited to four of nine sites. Faunal similarity between reef and either mangrove or seagrass habitats was low, suggesting little, if any exchange between them. Finally, although relative risk of predation was lower in mangrove/seagrass than in reef habitats, variance in rates was substantial suggesting that not all mangrove/seagrass habitats function equivalently. Specifically, relative risk varied between morning and afternoon, and between sites of similar habitat, yet varied little, in some cases, between habitats (mangrove/seagrass vs. coral reefs). Consequently, our results caution against generalizations that all mangrove and seagrass habitats have nursery function.

Tropical harmful algal blooms: an emerging threat to coral reef communities?

Tropical harmful algal blooms (HABs) are increasing in frequency and intensity and are substantially affecting marine communities. In October/November 2008 a large-scale HAB event (> 500 km(2), dinoflagellate Cochlodinium polykrikoides) in the Gulf of Oman caused the complete loss of the branching corals, Pocillopora and Acropora spp., and substantial reductions in the abundance, richness and trophic diversity of the associated coral reef fish communities. Although the causative agents of this C. polykrikoides bloom are unknown, increased coastal enrichment, natural oceanographic mechanisms, and the recent expansion of this species within ballast water discharge are expected to be the main agents. With rapid changes in oceanic climate, enhanced coastal eutrophication and increased global distribution of HAB species within ballast water, large-scale HAB events are predicted to increase dramatically in both intensity and distribution and can be expected to have increasingly negative effects on coral reef communities globally.

Fish communities on the world's warmest reefs: what can they tell us about the effects of climate change in the future?

To examine the role of climatic extremes in structuring reef fish communities in the Arabian region, reef fish communities were visually surveyed at four sites within the southern Persian Gulf (also known as the Arabian Gulf and The Gulf), where sea-surface temperatures are extreme (range: 12-35° C annually), and these were compared with communities at four latitudinally similar sites in the biogeographically connected Gulf of Oman, where conditions are more moderate (range: 22-31° C annually). Although sites were relatively similar in the cover and composition of coral communities, substantial differences in the structure and composition of associated fish assemblages were apparent. Fish assemblages in the southern Persian Gulf held significantly lower estimates of abundance, richness and biomass, with significantly higher abundances of smaller sized individuals than Gulf of Oman assemblages. Functionally, southern Persian Gulf sites held significantly lower abundances of nearly all the common fish trophic guilds found on Gulf of Oman sites, although higher abundances of herbivorous grazers were apparent. These results suggest the potential for substantial changes in the structure of reef-associated fish communities, independent of changes in habitat within an environment of increasing fluctuations in oceanic climate.

Urban breakwaters as reef fish habitat in the Persian Gulf

Breakwaters and related structures dominate near-shore environments in many Persian Gulf countries, but little is known of their ecology. To examine the influence of wave exposure on fish communities we surveyed exposed and sheltered breakwaters seasonally over 2 years and compared these with natural reef assemblages. Species richness and adult, juvenile, and total abundance were generally comparable among the three habitat types each season. However, differences in multivariate community structure indicated that each habitat contained a distinct assemblage, with strongest difference between sheltered breakwaters and the exposed natural reef. All communities were characterized by marked seasonality; abundance and richness were generally higher in the warmer seasons (summer, fall) than during cooler periods (winter, spring), and there were related seasonal changes in community structure, particularly on the natural reef. Results indicate that breakwaters are important fish habitats, but that breakwater communities vary with wave exposure and are distinct from natural reefs.

Using otolith microchemistry ofHaemulon flavolineatum (French grunt) to characterize mangroves and coral reefs throughout Turneffe Atoll, Belize: Difficulties at small spatial scales

We investigated whether the otolith chemistry ofHaemulon flavolineatum (French grunt), a nocturnally active fish, could be used as a means to differentiate individuals occupying mangrove and coral reef habitats. In 2003, adults were collected from 9 mangrove and 10 coral reef sites throughout Turneffe Atoll, Belize. Concentrations of trace elements were measured at the edge of sagittal otoliths by laser ablated inductively coupled plasma mass spectrometry. Results of a two-factor nested MANCOVA (sites nested within habitat and covariate of fish size), used to investigate whether significant differences in otolith elemental concentrations existed between habitats (i.e., mangrove versus reef) and among sites, indicated significant differences between habitats, in terms of lithium, magnesium, zinc, and rubidium (fish from mangroves had greater concentrations than those from coral reefs), as well as among sites (for several elements). Because elemental variability existed between habitats and among sites, we asked whether this variability was sufficient to differentiate habitats and sites using separate linear discriminant function analyses (LDFA). LDFA indicated that fish were classified to the habitat (mangrove or reef) from which they were collected with a moderate degree of accuracy (correct classification of 74% and 79% for mangrove and coral reef fish, respectively), but were poorly classified to the site from which they were collected (average correct classification of 46% with a range of 0–89%). Otolith microchemical investigations ofH. flavolineatum at Turneffe Atoll can be used to identify movement between habitats, yet due to the lack of unique site-specific chemical signatures likely caused by the nocturnal movement of individuals, it will not be possible to identify specific sites from which reef fish originated.

Water Currents and Water Budget in a Coastal Megastructure, Palm Jumeirah Lagoon, Dubai, UAE

Abstract Palm Jumeirah is the most completely developed of several man-made coastal island megaconstructions in Dubai, United Arab Emirates. The palm-shaped island, surrounded by an elliptical breakwater, was developed 7 y ago, has an overall footprint of 23 km2, of which the constructed island surface area is 7.9 km2, and is connected to shore via a 5-km-long spine from the mainland to the crescent tip. Time-series observations of hydrographic variables and currents within the interior of the development (Palm Jumeirah Lagoon) during 30 d in April–May 2008 were utilized to examine current flow, tide variability, water budget, vertical mixing, and turnover time within this megastructure. Currents within Palm Jumeirah Lagoon varied between stations; however, similar water temperatures and salinities were apparent throughout all the stations. Palm Jumeirah Lagoon tides were mixed and mainly semidiurnal, with spring and neap tidal ranges measuring 116 and 56 cm, respectively, and no difference in amplitude or phase throughout Palm Jumeirah Lagoon. There were substantial differences in water discharge between the east and west entrances, with high discharge on average exiting the eastern entrance and low discharge exiting the western entrance. These results indicate that the eastern and western halves of Palm Jumeirah Lagoon are flushed unequally and show differences in residence times (1.2 and 42 d, respectively), due to differences in tidal currents, wind influence, and variability of the bathymetric contour. Previous numerical modeling studies of water residence time within Palm Jumeirah Lagoon did not capture this difference, which could be associated with the exclusion of bathymetric variability in the previous modeling. Due to the strong shear and weak saline stratification, the water column throughout Palm Jumeirah Lagoon remained instable, with vertical mixing present during the spring-neap tidal cycle and well-mixed conditions predominating throughout the lagoon system.

Collaborative Approach to Fisheries Management as a Way to Increase the Effectiveness of Future Regulations in the Galapagos Archipelago

For coastal fishing communities, it is becoming increasingly clear that the key to success is community-based comanagement, which incorporates all users and stakeholders in the decision-making processes about fisheries management. Established regulations can easily fail due to lack of enforcement. However, many coastal communities do not have the economic resources for the necessary enforcement and therefore rely on compliance by fishers. There are about 400 local fishers in the Galapagos Marine Reserve (GMR), who depend on the exploitation of coastal resources for their living. Evidence shows that the GMR suffers from lack of compliance; coastal resources have been overexploited and illegal fishing has been observed. The results of interviewing 26 % of Galapagos’ active fishers show no trust in scientific studies, lack of income alternatives provided, no dissemination of results, and lack of participation of fishers in the studies. We argue that the abovementioned problems can be tackled by using a collaborative approach, which includes fishing community members in each step of the research process. This would foster a sense of belonging among the Galapagos fishers, who are currently an underrepresented part of the already-established comanagement scheme, which has yet to achieve sustainable fisheries in the Galapagos Islands.

So Long and Thanks for All the Fish: Overexploitation of the Regionally Endemic Galapagos Grouper Mycteroperca olfax (Jenyns, 1840).

The regionally endemic Galapagos Grouper, locally known as bacalao, is one of the most highly prized finfish species within the Galapagos Marine Reserve (GMR). Concerns of overfishing, coupled with a lack of fishing regulations aimed at this species raises concerns about the current population health. We assessed changes in population health over a 30-year period using three simple indicators: (1) percentage of fish below reproductive size (Lm); (2) percentage of fish within the optimum length interval (Lopt); and (3) percentage of mega-spawners in the catch. Over the assessed period, none of the indicators reached values associated with healthy populations, with all indicators declining over time. Furthermore, the most recent landings data show that the vast majority of the bacalao caught (95.7%,) were below Lm, the number of fish within the Lopt interval was extremely low (4.7%), and there were virtually no mega-spawners (0.2%). Bacalao fully recruit to the fishery 15 cm below the size at which 50% of the population matures. The Spawning Potential Ratio is currently 5% of potential unfished fecundity, strongly suggesting severe overfishing. Our results suggest the need for bacalao-specific management regulations that should include minimum (65 cm TL) and maximum (78 cm TL) landing sizes, slot limits (64–78 cm TL), as well as a closed season during spawning from October to January. It is recognized that these regulations are harsh and will certainly have negative impacts on the livelihoods of fishers in the short term, however, continued inaction will likely result in a collapse of this economically and culturally valuable species. Alternative sources of income should be developed in parallel with the establishment of fishing regulations to limit the socio-economic disruption to the fishing community during the transition to a more sustainable management regime.