Search

Temporal trends in the recovery of exploited species in marine protected areas (MPAs) are useful for a proper assessment of the efficacy of protection measures. The effects of protection on the fish assemblages of the sublittoral rocky reefs in the "Penisola del Sinis-Isola di Mal di Ventre" MPA (W. Sardinia, Italy) were evaluated using a multi-year series of data. Four surveys, conducted 7, 10, 13 and 15 years after the area was designated as an MPA and carried out in the period spanning June and July, were used to estimate the abundance and biomass of commercial species. The surveys were carried out in zones with decreasing levels of fishing restrictions within the MPA (zones A, B, C) and in unprotected zones (OUT1 and OUT2), and underwater video visual census techniques were used. Protected zones only occasionally showed higher levels of abundance or biomass, and the trajectories of those metrics were not consistent across the years. In addition, the zone with the highest level of protection (zone A) never presented levels of abundance and biomass higher than those in zones B and C. This study shows that even 15 years after designation, protection has had no appreciable effect in the MPA studied. It is argued that this is emblematic of several shortcomings in the planning, regulation and enforcement frameworks of the MPA.

The changes in a marine community in the northern Adriatic Sea were explored over a period of 65 years using landings data from a commercial fishing fleet, and the role of fishing pressure and environmental variations in driving these changes was investigated. A total of 40 taxonomic categories, including one or several species, were analysed, representing 93·7% of the total landings. From 1945 to 2010 a significant decrease in the evenness index was observed, indicating a trend towards landings dominated by fewer taxa. The composition of the landings showed a temporal shift during the 1980s; from 1945 to the 1980s a continuous, clear change in composition took place, probably driven by an increase in fishing pressure as well as riverine nutrient inputs. Since the 1980s, a different trend of changing composition emerged. Among the analysed predictors, fishing capacity, summer seawater temperature, inflow from the Po River (the major river of the northern Adriatic Sea) and nutrients were related to the changes in landings. In relation to life-history traits of the landed species, the community shifted from large, late-maturing species to more fecund, smaller and earlier-maturing species. A high fishing pressure is probably the major cause of these changes, possibly acting synergistically with environmental variations., (© 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.)

The black goby, Gobius niger, shows alternative male mating tactics, i.e., parental and sneaker males. Males release a sexual pheromone that attracts females and stimulates aggressive displays in males. This pheromone is produced by the mesorchial gland, a structure well developed in parental males but markedly undeveloped in sneakers. We measured the behavioral response of parental males to the ejaculates of males performing different reproductive tactics. Parental males reacted to the ejaculate of other parental males, with stereotypic aggressive behaviors, but not to the ejaculate of sneakers; consequently sneaker male ejaculate appears to be pheromonally inconspicuous., (Copyright 2002 Wiley-Liss, Inc.)

In this study we examined the effect of: observer presence; observer speed; and the impact that multiple surveys had on the number of counted fish in a visual census survey in a typical Mediterranean rocky habitat. SCUBA observer presence had no influence on the number of fish per survey. An improvement in the methodology to estimate the number of fish was demonstrated by using two different speeds: slow speed for benthic species and higher speed for epibenthic ones. No differences in the number of fish per survey were found among successive surveys along the same transects, even with the shortest time interval used: 5 min. We also examined the ability of observers to estimate fish length during visual census by using wooden fish models. Significant differences in size estimations were found using two different estimation methods (i.e. size-classes estimates and continuous measures). Estimating fish length to a size class was more accurate in estimating size, while transformed size to calculate biomass from length estimates was more accurate using continuous measures.

The study tested the role of body size and of nest size in female mate choice in the marbled goby, Pomatoschistus marmoratus. The results show a female preference for smaller males, supporting the idea that smaller males may be preferred to larger ones in the absence of male-male competition. No effect of nest size was detected, suggesting that other nest characteristics, beyond nest size, may be implicated. [ABSTRACT FROM AUTHOR]

The grass goby Zosterisessor ophiocephalus sperm-duct gland extract displayed antimicrobial activity against gram-positive and gram-negative bacteria. This suggests that sperm-duct gland mucins might be functional in protecting eggs and possibly parents from pathogens, an activity of great adaptive value for Z. ophiocephalus, which lays eggs in mud nests. [ABSTRACT FROM AUTHOR]

To investigate the relationship between fertilization modalities and the morphology of male reproductive apparatus, two species of Auchenipteridae, Auchenipterus nuchalis and Tatia intermedia, and six species of Callichthyidae, Callichthys callichthys, Corydoras aeneus, Corydoras bondi, Corydoras ehrhardti, Corydoras potaroensis and Hoplosternum littorale were studied. The species analysed show either internal or external fertilization, the latter including the so called ‘sperm drinking’ type of mating. An anal fin modified as an intromittent organ, a pair of seminal vesicles, and the release of sperm in the form of discrete bundles (spermatozeugmata) characterize the male reproductive apparatus of the internal fertilizer A. nuchalis. Seminal vesicles are present also in C. aeneus, C. bondi, C. ehrhardti, C. potaroensis and H. littorale, species performing ‘sperm drinking’ spawning. In contrast, regardless of the family, species showing the more classic type of external fertilization lack specialized accessory organs. Where occurring, the major function of seminal vesicles is the secretion of mucins. The role of these mucosubstances, in relation to spermatozeugmata formation, in internal fertilizers, or the protection of sperm passing through the female gut, in the ‘sperm-drinking’ species, is discussed. Variation, between families, in the shape of testis and accessory structures, as well as in the type of spermatogenesis was found. Neither the reproductive modalities nor the phylogenetic relationships, however, appear to fully account for these differences. [ABSTRACT FROM AUTHOR]